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#1316257 - 01/01/13 05:29 PM Sterile lines
KaliKatka Offline
Joey Member

Registered: 07/09/11
Posts: 102
Loc: Michigan
Sterile lines

Hello glider community, I just found out my breeding leucistic male comes from "proven" sterile lines when a breeder buying his first born son backed out of the deal because of it. When I got him, his breeder had told me he was from clean non-sterile lines, something I didn't fully understand at the time, but was glad to hear since I knew sterility would put a damper on my plans. Naturally, learning that this was not true sent me into research mode to find out everything I could about the sterile lines and the implications to the health and wellbeing of my joeys. He happens to be descended from the Champagne sterile line from Priscilla Price, through Lorie, who has not had a known sterile descendant in over 100 documented joeys, details here
http://www.petsugargliders.com/sterile.php

I am a semester away from completing my masters degree in cell and molecular biology, so I have a firm grasp on genetics, but I am new to breeding sugar gliders and thus have a tenuous grasp on sugar glider genetics and especially history. I would like to summarize what I've learned along with my own interpretation of it so that I can have its accuracy verified by experienced breeders, as well as to help other new breeders and owners if this issue arises for them.

Male sterility

Male sterility can manifest as complete lack of testicles, a flattened sac into which the testes never drop, or normal looking but non functional. It was associated with several inbred mosaic lines and a champagne line that Priscilla Price acquired from a breeder that didn't keep records. There is a glider central thread covering some of the mosaic lines history. Unfortunately, it makes scarce mention of the champagne line.

http://www.glidercentral.net/ubbthreads/...ic_L#Post941771

From Gliderboy4life "There are many different sterile mosaic lines, there is Sally, Ms. Leu, Lollie, Tilly, Helena, Heidi, Bianca and maybe a few others."

The gene for sterility is believed to be x-linked

Tilly is not in my glider's lineage, but she provides relevant evidence to distinguish whether or not sterility is recessive, so she will be used for my examples.

Gliderboy4life originally posted "Tilly is a sterile line, champ is not sterile. Tilly was paired with another male, a WF named casino and produced sterility."

Tilly and champ also have sterile joeys listed in the pet glider database. Since Tilly had sterile sons with two different (presumably unrelated) mates, it shows that the sterility is not a recessive condition. If it were recessive, then Champ and Casino would both have to already have the recessive gene for sterility in order for both of them to have sterile sons with Tilly, and only 1/4 of their sons would be sterile (1/2 if Tilly were homozygous for the gene). It's pretty unlikely that three unrelated gliders would share the same rare recessive gene unless the gene was already extremely widespread in the population, in which case many other sterile gliders would be born from other "non-sterile lines" all the time. If sterility is recessive, then every male that has ever produced sterile sons MUST have been from sterile lines. Therefore, all descendents and relatives of these males must also be considered to exhibit the exact same level of risk as those in the labeled "sterile lines".

The much more likely case is that the gene for sterility is either on the x chromosome or it is a dominant gene on a non sex chromosome (called an autosome), but only manifests in males since only the males have testicles. Whether x-linked or dominant, the inheritance pattern would be the same insofar as the males can't pass it on. In this case Tilly is the only parent that carries the gene, and half of her sons would be sterile regardless of the male she was paired with. From reading through the forums and other literature it seems most breeders agree with this and consider sterility x-linked.

From what I know about genetics, an x-linked or autosomal dominant gene that causes male sterility can never be passed on through a male. Any male that receives the dominant sterility gene would be sterile, and therefore unable to have children to pass it on to. If it is x-linked, a sterile male must receive the gene from his mother's x chromosome, since his father must give him a y chromosome, and he would then be sterile and unable to pass that x chromosome on. Therefore, if sterility is x-linked or dominant, a producing male from sterile lines has no chance of passing the sterility gene on to his children.

When to be cautious with sterile lines

If there is not a male between the sterility and the joey in question, then it remains possible that the joey could inherit the sterility gene. While you can definitively know that the joeys from a producing male do not carry the x-linked sterility gene, there is no way to know if the mother does not have the gene. If the mother is a carrier, then she has a 50% chance of passing it on to each joey. She could theoretically have 20+ fertile sons without having a sterile son, even though she has the gene and is secretly passing it on to her daughters. The odds of that happening would be the same as flipping a coin and getting heads 20+ times in a row. It's hard to accurately judge the odds that a female will have the gene without having access to complete and extensive records for every ancestor, and TPG can be a bit spotty once you go back a few generations. It has also been noted that people do not always list their pet only gliders in the database, and sterile males might therefore be missing from the records.


So why the stigma?

The question then becomes, if sterility has been shown to be x-linked or dominant (but only manifesting in males) why is there still a stigma associated with "proven sterile lines" that can show a producing male between the sterility and the joey in question? I've been diligently searching for the answer to this question, but haven't found anything particularly convincing. The argument seems to go as follows:

http://www.glidercentral.net/ubbthreads/ubbthreads.php/topics/982348/x_linked_genes_like_sterile_mo
From CandyOtte "There is also the possibility that the sterility, although known to be x linked, is also the process of a combined effect from other genes, on other chromosomes. The mosaic population is still relatively small so even though a male glider might not have the x chromosome that causes full sterility, he may have, and be able to pass on, other genes to his offspring that contribute to the problem"

To me, this is not a logically sound argument. If sterility were controlled by multiple genes, one of which is a recessive mutation found primarily in this sterile line, then Tilly would not have had sterile sons by two unrelated males. By using the same logic used to deduce that the trait was not recessive in the first place, both males would already have to have had the recessive gene in their lineages. Were this scenario true, the actual incidences of sterility would be drastically less. In order to get sterility, the joey would need to get the recessive gene from BOTH parents AND the x-linked gene from his mother. To put it into perspective, if sterility is controlled by at least two genes, then only 1/8th of the male sons would be sterile if the mother carried the x-linked gene and both parents were carriers of the recessive gene (meaning both parents would have to be from the sterile line). If this were the case, breeding out the x-linked gene would prevent the other recessive gene from causing sterility, thus eliminating the risk to the glider's health anyway.

From the evidence available, I would say no, sterility is not caused by multiple genes, one of which is recessive. The idea that there is a mysterious "second shooter" on this particular grassy knoll is not supported by the evidence. There is nothing to substantiate fears that "other hidden issues" (translate as recessive genes) remain associated with the line once the x-linked sterility gene has been bred out. Even some of those making such claims acknowledge that they have no evidence to suggest that such fears are warranted, simply that they think the possibility exists.

The lesser charge that there is a second recessive gene which contributes to reduced fertility but is not required for the x-linked gene to cause sterility is also not supported by the evidence. This argument rests on the assumption that two different mutations occurred in two different genes on two different chromosomes in the same lineage, both of which independently control male fertility, but that only the x-linked gene has been found and bred out because it was masking the other recessive infertility gene. So far I have seen no evidence that this has actually happened, and it strikes me as an unlikely scenario.

There certainly are many different genes on different chromosomes that could influence fertility. Reproduction is a complex process that requires interactions with a wide variety of genes. Mutations in those other genes could cause infertility, but most mutations occur randomly and independently, and can occur in any animal. I do not see a reason to believe that having the x-linked sterility gene in the lineage would increase their likelihood of also acquiring a mutation in a gene on another chromosome that happened to be functionally related. This situation is made even more unlikely by the fact that the genes cause sterility or reduced fertility, and therefore are somewhat naturally self-limiting in the population.

A word about inbreeding

The second major concern that is oft-repeated in the Glider Central forums is that the original gliders of the sterile lines were inbred.

http://www.glidercentral.net/ubbthreads/ubbthreads.php/topics/929657/Sterile_lines
From guerita "1 thing people tend to forget is WHY the sterile lines are sterile. It's due to inbreeding(SEVERE inbreeding!). Not just 1 accidental inbreeding, like with some of the leu lines, but inbreeding, after inbreeding, after inbreeding... Thus resulting in sterile gliders."

Yes, inbreeding is bad. No, inbreeding did not cause the sterility.

There is nothing inherent to inbreeding that creates new diseases. Genetic diseases are CAUSED by mutations. Mutations that lead to genetic diseases happen BEFORE fertilization even occurs, so mate choice cannot play a causal role in the initial generation of any new disease. Inbreeding does NOT cause mutations, therefore inbreeding does not cause genetic disease.

I do not condone inbreeding, but I do feel it is important to understand why it is bad and the actual consequences that arise from practicing it. Inbreeding is bad because when the parents are related, it is more likely they will both be carriers of the same recessive genes, and many genetic diseases are recessive. Inbreeding simply makes it more likely for the offspring to inherit the recessive gene from both the mother and the father, and therefore express the disease symptoms. Since the sterility gene is not recessive, inbreeding could not have played that role in causing the sterility.

It is possible that the sterility gene came from the wild population that began these lines. Consider that in the wild, gliders mate in colonies where alpha males mate multiple females. Perhaps a gene that makes half of the males sterile provides a selective advantage to the colony, since it would reduce tensions from mate competition among the males. I have no evidence for this hypothesis, but it's still an interesting thought. And it would help clarify why sterility is now being seen in unrelated lines (there was a post on a facebook group that mentions sterility coming from carmel lines.)

The stigma

In my opinion, the major problem with proven sterile lines is the stigma associated with them. Many breeders either do not understand the underlying genetics, or even though they do understand the genetics, they choose not to breed from proven sterile lines just in case. Some avoid the lines on principle in protest of the bad practices that began them. Some have stated opinions that any animal that has ever shown any defect should never be bred and that breeding sterile lines is a sign of an irresponsible breeder. The person that informed me of the problem said her reputation as a breeder would be damaged if she bred my joey because he is from sterile lines. This does not appear to be a unanimous opinion across the community, but it does exist, which can make finding good homes for otherwise perfectly healthy, beautiful joeys more difficult than is warranted.

http://www.petsugargliders.com/sterile.php
From Jennifer Chandler "This line has created a great controversy with a couple of sugar glider breeders. However, there is reason to believe that their conduct is more than to be the "glider police", but more of a financial motive. Usually their "warnings" are followed up with an offer for you to buy a glider from them or one of their "friends" instead."

Joeys are advertised with labels of non-sterile in their header line, and often have premium price tags to accompany the title. breeders of proven sterile lines have been requested to label their joeys as from sterile lines. I have not seen similar labels for any other health related genes in gliders, even though there must be a number of recessive disorders that have much worse consequences for the well-being of the glider than being unable to produce joeys. Perhaps it is simply the prevalence and community awareness of the sterile line that highlights it so much above other possible health problems.

My conclusions about my sterile line gliders

Our Ziggy is a gorgeous 100% leu het mosaic boy from healthy and happy parents. He is sweet, friendly, and loves to give face hugs. His sterile line leucistic father, Dazzle, is definitely fertile, as our joeys are just now turning eight weeks old and he already has two more in pouch. Both of our girls, Keeva and Kaylin (Snow White line), got pregnant almost immediately after introducing them to Dazzle. His line has been clean for five generations, with no sterile males born from Lorie onward. The known genetics say he's just fine. One of his 64 great, great, great, great, great, grandparents was inbred. Even if there were an undiscovered recessive gene in the same lineage, he shares approximately 0.7% of his genome with Sterling, so has less than a 1% chance of inheriting that hypothetical hidden gene.

I conclude from this that there is no legitimate concern about the genetics of my joeys arising from their sterile line lineage. Our gliders are under Ziggy - AP, Zappa -AP, Zeeva - AP, and Zeta - AP in the pet glider database. Lorie's lineage has been tracked and is available at http://www.petsugargliders.com/sterile.php.

Everything I can find thus far points to the sterility condition being an x-linked or autosomal dominant trait. That means neither Dazzle nor his offspring can possibly be carriers, so there should be no problem continuing to breed him and his offspring.

I respect the decision to avoid breeding from sterile lines, and will disclose the lineage to prospective buyers. However, I see no reason to believe that this is an irresponsible breeding decision, nor to assume that my joeys are in any way defective because of it.

At this point, I can find no compelling reason to discontinue breeding our glider. However, I know there is a large community of skilled and knowledgeable breeders here, and I know that some of you are familiar with Sterling’s line and its history, so I am asking you to please help if you can.

If you have any relevant knowledge or information, or can point to any source of data, discussion, or observational evidence that might broaden my understanding of the situation, please share it. PMs are welcome if you do not wish to participate in a thread about a controversial topic, and your desire for anonymity will be fully respected.

Of particular import would be any evidence to support the idea that a second, recessive trait may be causing sterility in the line, or that Sterling’s descendants carry some other genetic defect. If such evidence exists, I will gladly concede my point and be grateful for having gained a better understanding of sugar glider genetics and history.


Edited by KaliKatka (01/01/13 09:27 PM)
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Awesome Possum Sugar Gliders
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#1316275 - 01/01/13 06:46 PM Re: Sterile lines [Re: KaliKatka]
GliderNursery Offline
Glideritis Anonymous

Registered: 09/14/07
Posts: 20049
Loc: North Central Ohio
I tend to disagree that the sterility was not a result of inbreeding.

From from http://news2.onlinenigeria.com/news/brea...lems-study.html
Quote:
A recent research finding has shown that getting married to one’s cousin or blood relation makes one prone to infectious diseases and unexplained infertility problems.
The research, carried out by scientists at Ohio State University and in Spain , further showed that the family of the late Charles Darwin, who discovered the theory of evolution, have been suffering from the late scientist’s marriage to his first cousin.

Darwin married Emma Wedgwood and they had 10 children, but while three of the children died before age 10, three of the surviving children had long-term marriages that did not produce any offspring. This, the researchers believe, is a sign that the children of the late scientist could have had reproductive problems because of their lineage.


I have a very simplified explanation of the sterility issue in mosaics on my website. http://glidernursery.webs.com/mosaics.htm There I explain the controversy with breeding sterile lines and list the gliders names from both the sterile and non-sterile lines. These names are listed as links to their lineage on the Pet Glider Database.

At this point we do believe that it is a x-linked gene. I started a discussion on a facebook group about this exact topic, whether the fertile males born from sterile lines should be bred.

From what I have been told, and seen so far, there is one male, Jason that produced a joey, Magic that had a "reproductive issue". Magic was found to only have 1 testicle, but he did produce. He was neutered right away after this was noticed. Now, was his single testicle a fluke, was it from the sterility issue, or when he was neutered was the other found to be up higher? I don't know that anyone knows the answer to that.


Edited by GliderNursery (01/01/13 07:10 PM)
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#1316278 - 01/01/13 06:54 PM Re: Sterile lines [Re: KaliKatka]
KaliKatka Offline
Joey Member

Registered: 07/09/11
Posts: 102
Loc: Michigan
Prone to infections due to inbreeding is caused by a reduced variety of MHC alleles, and a reduced variety of alleles that are used to create antibodys and immune receptors. Each person has 12 "slots" for MHC alleles, anf inbreeding doubles up some of those slots, giving a minimum of 6 unique MHC alleles. It's understood to a decent extent in immunology, which I've only had one class in so I'm not sure I can explain it coherantly. Outbreeding reverses this within a generation.
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Awesome Possum Sugar Gliders
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#1316288 - 01/01/13 07:09 PM Re: Sterile lines [Re: KaliKatka]
GliderNursery Offline
Glideritis Anonymous

Registered: 09/14/07
Posts: 20049
Loc: North Central Ohio
I was referring to the part where it states "and unexplained infertility problems".
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#1316291 - 01/01/13 07:17 PM Re: Sterile lines [Re: KaliKatka]
KaliKatka Offline
Joey Member

Registered: 07/09/11
Posts: 102
Loc: Michigan
To get the exact mechanisms for that I would need to research it, I knew the infections part off the top of my head.

I do know this, reproduction is controlled by a large number of genes and a mutation in any one of them can cause sterility. Some of the mutations could be recessive thus their expression could be affected by inbreeding. Considering how distantly related Charles Darwin is to Sterling, I don't think it probable that their fertility issues arise from the same mutated gene. Especially considering the claim that the sterility gene in question originated from these lines and therefore are only present in these lines.
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Awesome Possum Sugar Gliders
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#1316298 - 01/01/13 07:28 PM Re: Sterile lines [Re: KaliKatka]
GliderNursery Offline
Glideritis Anonymous

Registered: 09/14/07
Posts: 20049
Loc: North Central Ohio
Very possible, but you have to realize the amount of severe inbreeding that was done when Helen Morano owned these lines. That level of inbreeding was thankfully never done in any of the other lines, which is most likely why we don't see in the others.
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#1316312 - 01/01/13 08:14 PM Re: Sterile lines [Re: KaliKatka]
KaliKatka Offline
Joey Member

Registered: 07/09/11
Posts: 102
Loc: Michigan
I caught a mention of sterility in the carmel line. Is this a distinctly separate line? Did it start from wild caught?
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Awesome Possum Sugar Gliders
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#1316316 - 01/01/13 08:38 PM Re: Sterile lines [Re: KaliKatka]
GliderNursery Offline
Glideritis Anonymous

Registered: 09/14/07
Posts: 20049
Loc: North Central Ohio
It is now being said that they think the original Champagne line may have actually been a Caramel glider. If that is the case, it's a situation of cross-breeding different sub-species. We know that breeding the Caramels with our gliders causes sterility. So I'm really hoping those with the Caramel gliders don't cross breed. crazy
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#1316320 - 01/01/13 09:24 PM Re: Sterile lines [Re: KaliKatka]
KaliKatka Offline
Joey Member

Registered: 07/09/11
Posts: 102
Loc: Michigan
Wouldn't sub species cross breeding produce steriles 100% of the time, like is common with mules. And wouldn't both sexes be affected? By original champagne line do you mean Sterling? Does someone have records of Sterlings ancestry that connects her to the carmel line? Or was that line descended from her? What is the reasoning behind retroactively relabeling the champagne line as Carmel? Where is this information made available?
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Awesome Possum Sugar Gliders
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#1316325 - 01/01/13 09:41 PM Re: Sterile lines [Re: KaliKatka]
GliderNursery Offline
Glideritis Anonymous

Registered: 09/14/07
Posts: 20049
Loc: North Central Ohio
I have a discussion going on about this on FB. Tyler said that he and Priscilla believe that the reason we have sterility is because the champagnes were actually caramels. When they were bred to the mosaics you got sterility.

I just asked them if they feel that was the cause rather than inbreeding.

ETA: Priscilla has also indicated that it is not an x-linked gene. Still trying to get more details on that.


Edited by GliderNursery (01/01/13 09:44 PM)
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#1316333 - 01/01/13 10:13 PM Re: Sterile lines [Re: KaliKatka]
KaliKatka Offline
Joey Member

Registered: 07/09/11
Posts: 102
Loc: Michigan
It need not be x-linked. It could be a dominant gene on a non sex chromosome that only affects males because only males have testicles. It still would not pass through males.

I'm still not clear if you are referring specifically to Sterlings line when you say the champagnes. Even if Sterling were a subspecies, our joeys are 7 generations removed from her. Is there any evidence to suggest that having a distant sub species relative is harmful to the gliders health or lineage other than the sterility that has been bred out?
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Awesome Possum Sugar Gliders
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#1316362 - 01/02/13 01:37 AM Re: Sterile lines [Re: KaliKatka]
KaliKatka Offline
Joey Member

Registered: 07/09/11
Posts: 102
Loc: Michigan
Ok, after reading through three facebook threads with 100 or so replies in them from two different facebook groups I found some info on the Caramel subspecies hypothesis. I would link the pages directly but I do not believe the group is public so unless you are part of the facebook group I don't think the link wouldn't help. I'm not really up on my facebook skills so if someone knows how to make the full content of these posts accessible please help.

There is also a confusing thread through the conversation where Priscilla denies that the sterility gene is sex linked and cites a producing male named Jason as having a sterile descendant.

I am not sure what to make of this yet. I looked up some information about sub species breeding and haven't come up with very much of relevance yet. I did find a wikipedia article saying that intra specific breeding of sub species often produced highly virile and over producing offspring. I'd love to find a study thats at least in the marsupial lineage since marsupials and eutherians (pretty much the rest of the mammals that arent from around australia) have some pretty big differences that makes extrapolation difficult.


Edited by GliderNursery (01/02/13 09:26 AM)
Edit Reason: edited text
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Awesome Possum Sugar Gliders
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#1316374 - 01/02/13 02:17 AM Re: Sterile lines [Re: GliderNursery]
KaliKatka Offline
Joey Member

Registered: 07/09/11
Posts: 102
Loc: Michigan
Originally Posted By: GliderNursery
I tend to disagree that the sterility was not a result of inbreeding.

From from http://news2.onlinenigeria.com/news/brea...lems-study.html
Quote:
A recent research finding has shown that getting married to one’s cousin or blood relation makes one prone to infectious diseases and unexplained infertility problems.
The research, carried out by scientists at Ohio State University and in Spain , further showed that the family of the late Charles Darwin, who discovered the theory of evolution, have been suffering from the late scientist’s marriage to his first cousin.

Darwin married Emma Wedgwood and they had 10 children, but while three of the children died before age 10, three of the surviving children had long-term marriages that did not produce any offspring. This, the researchers believe, is a sign that the children of the late scientist could have had reproductive problems because of their lineage.


So the next couple of paragraphs of this article explains exactly what I said about inbreeding, which I still maintain neither causes disease mutations nor can contribute to an x linked or dominant sterility gene's expression like it can for recessive genes.

"The researchers used these data to run calculations in a specialized computer program to determine what is called an “inbreeding coefficient,” or the probability that an individual received two identical copies of a gene resulting from marriages among relatives.
The analysis, according to them, showed a positive association between child mortality and the inbreeding coefficient for Charles Darwin’s children and others in the Darwin/Wedgwood families, suggesting that matching damaging genetic traits from the blood-relative parents could have influenced the health of the offspring."
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Awesome Possum Sugar Gliders
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#1316378 - 01/02/13 05:47 AM Re: Sterile lines [Re: KaliKatka]
KaliKatka Offline
Joey Member

Registered: 07/09/11
Posts: 102
Loc: Michigan
I've been admittedly obsessing about this a bit too much, but in the process I think I might have had a useful idea for genetic testing.

Genome sequencing prices are falling rapidly, and are predicted to reach $1000 shortly, if not already. Sequencing a Caramal, a sterile line glider very close to the origin of the lineage, and a non sterile line glider (also non mother white lines to be safe) I could probably determine whether the champagne line were Caramals or closely related subspecies, or at the least if they were different enough to have been a subspecies.

If it turns out they are a subspecies it would be relatively easy to design some simple genetic tests to determine if a glider was from that lineage, and give an idea of how closely they are related in the absense of trustworthy records. It wouldn't take much more than some free software, a used PCR machine and gel rig off craigslist, some reagents, and a lot of research time to pick the right sequences to check. And a few additional bred out genome sequences would help.

The test would take a drop of blood or some fur with attached root cells from the glider, about 6 hours until results were ready, and I would guess less than $20 per test for the consumable reagents, though it would depend on the level of accuracy desired.

Its just a thought, but it is at least possible and not so outrageously expensive that it isn't worth considering.
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Awesome Possum Sugar Gliders
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#1316415 - 01/02/13 09:37 AM Re: Sterile lines [Re: KaliKatka]
Srlb Offline
Glideritis Anonymous

Registered: 10/30/03
Posts: 16733
Loc: St. Johns, Florida
From just about every article I have read and the folks I have talked to have stated that inbreeding can indeed produce sterility in animals. One of the reasons it is so frowned upon. It can also lower the immune system (which is an issue we already see in many of our colored gliders) which allows more diseases to show their ugly heads.
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#1316416 - 01/02/13 09:38 AM Re: Sterile lines [Re: KaliKatka]
GliderNursery Offline
Glideritis Anonymous

Registered: 09/14/07
Posts: 20049
Loc: North Central Ohio
Here's another study that was done the proves inbreeding causes sterility.

From http://www.ncbi.nlm.nih.gov/pubmed/21310813:
Quote:
Infertility in cattle herds is a growing problem with multifactorial causes. Embryonic genotype and level of inbreeding are among the many factors that can play a role on reproductive efficiency. To investigate this issue, we produced purebred and crossbred bovine embryos by in vitro techniques from Holstein oocytes and Holstein or Brown Swiss semen and analyzed several cellular and molecular features. In the first experiment, purebred and crossbred embryos, obtained from abattoir oocytes, were analyzed for cleavage, development to morula/blastocyst stages, amino acid metabolism and gene expression of developmentally important genes. The results indicated significant differences in the percentage of compacted morulae, in the expression of three genes at the blastocyst stage (MNSOD, GP130 and FGF4) and in the utilization of serine, asparagine, methionine and tryptophan in day 6 embryos. In the second experiment, bovine oocytes were collected by ovum pick up from ten Holstein donors and fertilized with the semen of the respective Holstein sires or with Brown Swiss semen. The derived embryos were grown in vitro up to day 7, and were then transferred to synchronized recipients and recovered on day 12. We found that purebred/inbred embryos had lower blastocyst rate on days 7-8, were smaller on day 12 and had lower expression of the trophoblast gene PLAC8. Overall, these results indicate reduced and delayed development of purebred embryos compared with crossbred embryos. In conclusion, this study provides evidence that embryo genotype and high inbreeding can affect amino acid metabolism, gene expression, preimplantation development and therefore fertility in cattle.
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#1316459 - 01/02/13 02:08 PM Re: Sterile lines [Re: KaliKatka]
KaliKatka Offline
Joey Member

Registered: 07/09/11
Posts: 102
Loc: Michigan
I love how the scientific article says "provides evidence that" and you say prove. "Prove" is sort of a forbidden word in science, since scientists accept that they are not omniscient and that misinterpretation or incomplete data can lead to faulty conclusions. You might want to be careful how you represesnt information since it is often requoted as factual.

And yet again, this article strengthens my position that inbreeding's mechanism is to bring prexisiting recessive alleles together. It even demostrates that mating an inbred animal to an unrelated animal reverses this noticably within a single generation, something it could not do if inbreeding created new dominant or x linked mutations that didnt exist before.

I'm going to explain this one more time, then give it up as a lost cause. I'd rather not turn the sterile lines issue into a debate on the genetic mechanisms of inbreeding considering the sterile lines have been bred out for generations.

Disease, fertility, and almost every biochemical process in your body is controlled by genes. Genes code for the proteins your body uses to do almost everything it does. Like everything else in the body, genes make proteins that make reproduction possible. Reproduction is complex and requires a large number of different genes to interact just right.

Mutations in the gene leads to altered proteins that may not be able to perform their function. Almost all genes (but not those on the x chromosome in males) come in two copies, one copy from the mom the other from the dad, its a redundant system. If a mutation makes a vital gene non functional, there is a second backup from the second copy that can pick up the slack. If the second copy is also broken then there is not a back up and it may lead to problems.

Mutations happens all the time, in every animal, constantly. They are caused by many things, including oxidative stress from eating and breathing, as well as exposure to sunlight. It is a normal part of biology and necessary for evolution. If it happens in a sperm or an egg that mutation can then be inherited. Inheritable mutations occur BEFORE fertilization. If it were to occur after fertilization it would not be inheritable.

Inbreeding is about mate choice. Mate choice is fertilization. Mutations occur before fertilization takes place. Explain again how you think mate choice can cause mutations that lead to disease?

Inbreeding between relatives makes it more likely that two recessive genes come together, so if the line has a recessive problem it is more likely to manifest as a disease. This is similiair to the concept used to breed for leus or plats, both parents must already have the leu plat gene or you wont get leus or plats. You're argument is essentially saying (by analogy) that if you inbreed any two standard grays long enough you'll get leucistics and platinums. This is not the case, those genes must already exist in the line to get the recessive trait. This is just as true for reproductive genes as it is for coloration genes.

If the sterility gene is either x-linked or dominant as the preponderance of actual pedigree evidence suggests, then inbreeding could not have had any affect whatsoever on the sterility since males can not pass it on you are guarenteed that the male is "clean" if he can produce.

The paper you cited, but that I bet you didn't actually read, compared embryos from inbred cattle to embryos of inbred cattle mated with a non relative. So one group is fully imbred, the other is outbred by 1 generation. The embryos outbred by one generation showed improved development. This is because the recessive genes from the inbred line are being paired with working copies from the unrelated line. This is a great demonstration that the negative effects of inbreeding can easily be reversed within even a single generation. This reversal would not be possible if the genes that led to infertility were not recessive. My gliders are 7 generations out, giving them a 0.7% chance of recieving one recessive allele from this generation.

Another quibble I have, not every case of sterility in every animal on the planet is relavent to the sterility issue in sugar gliders. Cows are so far removed from sugar gliders evolutionarily speaking that any inferences made from their specific example would not have a lot of relavance since cows have different genes than sugar gliders. There is not one magic gene that all life shares that is soley responsible for reproduction. There are multiple different ways to inhibit reproduction that concern many many different genes. Unless there is an unbroken line of descent between your glider and the cows in this article throughout which the same sterility issue remanifests repeatedly you can not claim that they are the same mutations in the same genes. If you find an article thats at least from a marsupial it might be more relavant. They might at least have the same genes.
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Awesome Possum Sugar Gliders
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#1316461 - 01/02/13 02:25 PM Re: Sterile lines [Re: KaliKatka]
KaliKatka Offline
Joey Member

Registered: 07/09/11
Posts: 102
Loc: Michigan
I think the heart of this debate is causation vs correlation.
Inbreeding is correlated to reduced fertility, but it does not cause it. Reduced infertility is caused by mutations in the genes. Inbreeding is correlated to infertility because some mutations are recessive and inbreeding can bring recessive alleles together.

From wikipedia here are a few examples of the logical fallacy of correlation means causation.

B causes A (reverse causation)
The more firemen fighting a fire, the bigger the fire is observed to be.
Therefore firemen cause an increase in the size of

Example 3
As ice cream sales increase, the rate of drowning deaths increases sharply.
Therefore, ice cream consumption causes drowning.
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Kaylee
Awesome Possum Sugar Gliders
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#1316463 - 01/02/13 02:45 PM Re: Sterile lines [Re: KaliKatka]
KaliKatka Offline
Joey Member

Registered: 07/09/11
Posts: 102
Loc: Michigan
Originally Posted By: KaliKatka
Ok, after reading through three facebook threads with 100 or so replies in them from two different facebook groups I found some info on the Caramel subspecies hypothesis. I would link the pages directly but I do not believe the group is public so unless you are part of the facebook group I don't think the link wouldn't help. I'm not really up on my facebook skills so if someone knows how to make the full content of these posts accessible please help.

There is also a confusing thread through the conversation where Priscilla denies that the sterility gene is sex linked and cites a producing male named Jason as having a sterile descendant.

I am not sure what to make of this yet. I looked up some information about sub species breeding and haven't come up with very much of relevance yet. I did find a wikipedia article saying that intra specific breeding of sub species often produced highly virile and over producing offspring. I'd love to find a study thats at least in the marsupial lineage since marsupials and eutherians (pretty much the rest of the mammals that arent from around australia) have some pretty big differences that makes extrapolation difficult.


This post has been retroactively editted by the moderator to remove all quotes from the facebook groups. Therefore the information it originally contained is missing and it leads to misinterpretations. Priscilla's evidence that the gene was not x-linked was that Jason, a producing male from sterile lines, had a daughter, that had a son Magic that was producing but only had one testicle. The other lines were clean, therefore Magic could not have inherited a recessive gene from those other lines.

There was also a lot of info on the Caramel speculation. I will have to find all of that again in the threads and will update this later with a paraphrasing of the posts or quotes to them if that is permissable. Suffice it to say the hypothesis that Sterling was a Caramel is based on the fact that Caramels can produce sterile offspring and they have similar coloration, though different tails. This is often repeated with strong warnings that this is just a guess.

I would also like to add that regardless of the origination of the sterility gene, be it random mutation, inbreeding, or subspecies mating, its pedigree still shows that it is x-linked or dominant and can be bred out of the line, and there is not evidence to suggest that these lines suffer from any other detrimental effects.


Edited by KaliKatka (01/02/13 02:50 PM)
Edit Reason: Added final comment
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Awesome Possum Sugar Gliders
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#1316473 - 01/02/13 03:35 PM Re: Sterile lines [Re: KaliKatka]
GliderNursery Offline
Glideritis Anonymous

Registered: 09/14/07
Posts: 20049
Loc: North Central Ohio
I have mentioned many times that I have no scientific nor genetic background. I can only go from the information that has been provided and what we see with the lineage in the lines of sterile gliders.

Regardless of where it came from, or how they became sterile, the fact remains that they are.

In reading the over 100 posts, did you read my comment that started the discussion? I was basically saying that the fertile males from the sterile lines should be ok to breed if it's an x-linked gene, and was asking for others' opinions of that as well.

Here is my original post:
Originally Posted By: GliderNursery
Since sterility has been determined to be a sex-linked gene, I understand not breeding the females since they pass it on to the offspring, but since the "fertile" males cannot pass it, is there a problem breeding them? I mean, since they can't pass it on, then all of their offspring would be fertile and also couldn't pass it on, right?


Also, from what I have heard with these lines, producing sterile-line mosaics have had offspring showing no infertility for 5 generations then it has shown back up. (This information is from the breeder, I'd have to look at the specific line to know for sure.) If this information is true, then we have not had evidence that is can be bred out on the female side.
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#1316490 - 01/02/13 05:18 PM Re: Sterile lines [Re: GliderNursery]
LadyRaven Offline
New Member

Registered: 04/13/07
Posts: 17
Loc: Henderson, CO
Actually, it should not be an assumption that sterility is caused by a single mutation. After 5 generations of successful breeding there may be a new random mutation affecting sterility. Also, there may be a certain sequence or sequences that are more prone to random mutations.

And, when speaking of inheretance, single allele genetics may not be the only analysis needed: there may be polygenic issues, or gene penetrance issues.
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#1316506 - 01/02/13 06:08 PM Re: Sterile lines [Re: GliderNursery]
KaliKatka Offline
Joey Member

Registered: 07/09/11
Posts: 102
Loc: Michigan
I'm sorry Shelly, you are right, I am taking my frustrations out on you because you're the only one nice enough to respond to me and I truly apologize for my tone and behavior. Biology is my passion and I get a bit ... overzealous when talking about it. Sugar gliders are your passion and I truly welcome you sharing that passion and your experience with me as I am new to them and rather invested at this point.

I am trying to learn everything I can about this line and verify as much of it as I can. Throughout the discussions about sterile lines, there is a lot of misinformation and uncited claims that keep being repeated as proven facts but few have held up to any level of scrutiny thus far. At this point in my research I do not see a cause for concern when breeding a producing male from a sterile line, regardless of the original origin of the sterility gene. The pedigree does not support the hypothesis that sterility is recessive, which is the only hypothesis offered that would present any risk that a producing male could pass on the gene.

If there really is a cause for concern I do not wish to jeopardize the health and well being of my gliders or their descendants and would like to know its actual cause so that I can make informed breeding decisions. If there is not cause for concern I would like that the community stop condemning perfectly healthy lines and their breeders. There is no justifiable reason to create a "second class citizen" status for producing sterile lines. breeders should be encouraged to make decisions based upon the pedigree of the glider, not on a rule of thumb repeated so often that it becomes law in the community, as is being seen with the issue of sterile lines. This is what I am frustrated with, not you personally and I am ashamed that I directed it toward you.
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Kaylee
Awesome Possum Sugar Gliders
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#1316511 - 01/02/13 06:16 PM Re: Sterile lines [Re: LadyRaven]
KaliKatka Offline
Joey Member

Registered: 07/09/11
Posts: 102
Loc: Michigan
It is not an assumption, it is an interpretation of the pedigree. I addressed polygenics (multiple genes needed to create the sterility), as well as the other new mutation hypothesis in my original post. Neither have been corroborated by the available pedigree.

Gene penetrance isn't something I have considered yet, I will look into it further, thank you.
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Kaylee
Awesome Possum Sugar Gliders
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#1316517 - 01/02/13 06:26 PM Re: Sterile lines [Re: KaliKatka]
GliderNursery Offline
Glideritis Anonymous

Registered: 09/14/07
Posts: 20049
Loc: North Central Ohio
KaliKatka, thank you very much for that post! I truly understand where you are coming from and I am just as eager to learn the truth behind the issue as well.
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Shelly

Don't sacrifice quality information for convenient information.


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#1316742 - 01/03/13 09:54 PM Re: Sterile lines [Re: KaliKatka]
NatalieFuzzbutt Offline
Glider Explorer

Registered: 05/10/12
Posts: 210
Loc: Springfield,MO.
Holy Crap girls..That was impressive!! When you get your research done can you make some charts,graphs and basic pictures and have a class?? I will attend!! I am not mocking you..I am truly impressed! I have only been involved with gliders a short time and have nothing near your education and have also noted the "lack" of supportive evidence and the large amount of "opinion" Would love to see this research be put into a document for "newbies" and less educated!! I would love to pick your brains but need tooo many pictures and graphs. lol Somebody please write a book and squelch some of the "opinionators"!! Thank you!
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#1316763 - 01/04/13 01:41 AM Re: Sterile lines [Re: KaliKatka]
KaliKatka Offline
Joey Member

Registered: 07/09/11
Posts: 102
Loc: Michigan
Thank you Natalie!

I'm now in contact with Dr. Clare Hollelley who has been collecting sugar glider samples for genetic testing for years. She is doing phylogentic studies to determine their origins and level of inbreeding as well as other aspects of their genomics and distribution. She is currently based in Australia and has invited me to consider a PhD program in the field. So maybe I will write a book on it someday, who knows wink

Btw, a call out to breeders for DNA samples of their lines to send to Dr. Hollelley?
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Kaylee
Awesome Possum Sugar Gliders
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#1316795 - 01/04/13 08:49 AM Re: Sterile lines [Re: KaliKatka]
GliderNursery Offline
Glideritis Anonymous

Registered: 09/14/07
Posts: 20049
Loc: North Central Ohio
I have been talking to PhD's outside of the glider world for a couple of months to see what it would take to get genetic testing started on gliders. It's great to have someone with a lot more knowledge than me that can help get this going.

Kaylee, I would be willing to get some DNA samples such as we discussed in PM of my gliders to submit. When we get to that stage - let me know.
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Shelly

Don't sacrifice quality information for convenient information.


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#1316797 - 01/04/13 09:10 AM Re: Sterile lines [Re: KaliKatka]
GliderNursery Offline
Glideritis Anonymous

Registered: 09/14/07
Posts: 20049
Loc: North Central Ohio
However, I would like to update people on what has transpired within the FB group regarding the information that we have from sterile lines.

I took the information that Priscilla Price from The Pet Glider has provided (and had her verify that I wrote it down correctly), along with the information that we know (at this time) and complied a brief explanation of what is/has happened within the mosaic lines. I have done so in hopes of providing the information so people can make educated decisions on whether they want to purchase/breed these lines of gliders. Please realize, that this is from what we have experienced to date and based on breeders opinions. Hopefully someday we will have genetic testing done so we can know for sure what is/has happened within these lines, how it came about, and how to prevent it in the future.



The following information can be found on my website: http://glidernursery.webs.com/mosaics.htm

When breeding sugar gliders with the mosaic gene, it is important to know some information about the lines you are, or plan to breed. There are sterility issues in some of the lines, and I feel it is important for people to know what these lines are so they can make an educated decision about adding them into their breeding program.

I will assume that if you are considering breeding for the mosaic gene, you are already knowledgeable about lineage, genetics and how to ensure the pairing is genetically compatible.

In my personal opinion, I don't feel that we should cross the sterile line mosaic gliders with other lines. By doing so, you are introducing the sterile defect into an otherwise "clean line". Many breeders feel that sterile line gliders should not be bred at all, while others feel it is fine. That is a decision that you as a breeder must research and decide for yourself. breeders also need to be aware that the sterility gene will pass to any color glider, not just the mosiac gliders.

It is believed that some of the founding line mosaics, originally bred by Helen Moreno, were inbred to the point of introducing sterility into the genetics, or were possibly cross-bred with the Caramel sub-species to introduce sterility in the lines. The sterility gene is predominately passed from the female to the males. This means that the females are always fertile, but they may produce sterile males; which is how the sterility can continue to be passed. Additionally, information was provided by Priscilla Price that she has in fact had male gliders (specifically Jason and Freddy - mosaic - TPG, as well as others) from sterile lines paired with non-sterile line females produce sterile males.

With this new information, we cannot say for certain that it will only ever pass through the females. Although Priscilla indicated that the males that passed the sterility was from the early generations. At this time, I am not aware of any other males that have produced sterile offspring.

last updated: January 2, 2013

Sterile Lines
The founding gliders that you should be aware that carry the sterility gene are:

Loli - White Mosaic - TPG

Tilly - ringtail

Cammie (ringtail)

Helena - mosaic

Julie(champagne)

Ms. Leu

Sally - mosaic

Heidi

Bianca - deceased

Sterling (champagne)


If you have any of these gliders names listed in your gliders lineage (you may need to look all the way to the beginning of the lines), then it is from sterile lines. This does not mean your glider is sterile, but if it is a female, the she does have the potential of carrying and passing the sterile gene on to her male offspring.

Names are listed as they appear in The Pet Glider Database. Information in parenthesis is provided to further explain which glider is referred to as being from the sterile lines. To view the lineage, please click on the glider's name.

NON-Sterile Lines
The founding lines that do not have the sterility gene are:
Mac & Cheese
Mother White

As long as the descendants from these lines have not been crossed with the sterile lines, then these gliders would not be considered sterile line mosaics. To view the lineage, please click on the glider's name.

Producing Sterile Lines
Producing Sterile lines are gliders that have not shown to have passed the sterility gene to the offspring. At this point, it is not known for sure that the sterility defect can be bred out of gliders. Some breeders feel that after 5 generation of "producing males" with no sterile male offspring, the line is considered "Producing". However, we have seen 5 generations of producing sterile line gliders, then the sterility pop back up in the 6th generation.

It is my opinion that the gliders, even though producing, should still be considered "Sterile Line". This will prevent the problem of buying a glider and not knowing of the historical sterility issue. Additionally, if a sterile glider is then produced in later generations, it should be noted in The Pet Glider Database and made known so other breeders are aware of it coming back into the line.
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Shelly

Don't sacrifice quality information for convenient information.


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#1316815 - 01/04/13 12:19 PM Re: Sterile lines [Re: KaliKatka]
NatalieFuzzbutt Offline
Glider Explorer

Registered: 05/10/12
Posts: 210
Loc: Springfield,MO.
Girls I am not a breeder but I am sending out messages to read this article to other breeders. Hope they can help you out with samples...I'm volunteering their gliders and they don't know it...lol
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#1316830 - 01/04/13 01:56 PM Re: Sterile lines [Re: KaliKatka]
Hperk Offline
Glider Explorer

Registered: 10/25/10
Posts: 206
Loc: Ozark, MO
I have Magic's father who has produced his 2nd set of joeys for me (beautiful ones at that!)
I called my vet over to do a thorough check on him after I found out about Magic's 'testicle issue'. Hocus has both of his :yes:
I would love to know more of your thoughts on this line.
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