IANBC (I Am Not Bob C), but this is too much fun for me to resist. Bob's answer will be even longer than mine, since I only have a single weak copy of the lecture gene, but it's still probably as long as you can stand. B-) Regina J. Hart" <ferret@u...> wrote: >In light of your discussion regarding depigmentation, is it possible for >a ferret to express a depigmented pattern (e.g. blaze, mitt, panda, bib, >etc.) without the presence of the Star Gene and/or Waardenburg's Syndrome? Sure. But that doesn't mean that the resulting depigmentation isn't associated with problems. There are lots of genes involved in the development, structure and functioning of pigment cells, and any one of them could have one or more alleles that result in some degree of depigmentation. Since many (maybe even most) genes affect more than one trait, an allele that causes depigmentation is likely to have other effects. White patterns associated with deafness are NOT always caused by the genes associated with Waardenburg's Syndrome (WS). There are five genes that are implicated in the different types of WS. These genes are called PAX3, MITF, EDNRB, EDN3 and SOX10. However, most white markings in domestic animals appear to be related to the KIT gene, which is often referred to as the "S" ("spotting") locus in discussions of coat-color genetics. White markings caused by alleles of this gene are also associated with deafness, and can range from forehead markings to extreme piebald patterns. For example, this is the gene that is responsible for the coat pattern of Dalmatian dogs, as well as the high incidence of deafness in that breed. (Question: has anyone actually SHOWN that deaf ferrets with white markings are usually suffering from WS, or have we just been going along with an assumption somebody once made? My guess is that we've been using the term far too casually, and that the KIT gene is largely responsible for blazes, pandas, etc.) More about problems related to white markings below. But, first it's interesting to ask if there exist any genetic mechanisms that can cause depigmentation with NO associated problems. My guess on this would be yes. There are a number of species that appear to exhibit some type of depigmentation, but certainly aren't domesticated (no Star gene): skunks have stripes, badgers have blazes, zebras are striped, and panda bears are ... well ... panda. It seems unlikely that these patterns would persist in the wild if they were associated with some detrimental condition such as deafness, which means that the underlying genetic causes are probably different than the common causes of depigmentation in domestic animals. (OTOH, it is possible that these species derive so much survival benefit from their coloration that it more than makes up for a certain percentage of defective offspring. Somehow I find this hard to believe, though.) So, why aren't these "safe" depigmentation genes working in our domestic animals? Darned if I know. They aren't all that common in the wild, so maybe we just need to wait a couple million years for the right mutation to show up. Or, maybe they *are* here, but we just can't tell. For example, if I have two panda ferrets that aren't deaf, how would I know if one was a mild case of WS while the other has some "safe" genotype? Someday maybe there will be a Ferret Genome Project and we will then have genetic tests that can tell the difference. (I should also note that there is a difference between "depigmented" and "white". If the hair is white but the skin can produce pigment, then the animal is not depigmented. For example, Samoyed dogs are depigmented, but polar bears are not, having black skin.) >In addition to auditory and visual problems, what -if any- other problems >are documented in Star Gene and/or Waardenburg's Syndrome individuals? There are a zillion problems (scientifically speaking B-) associated with various types of depigmentation. Failure of the neural tube to close, cleft palate, enlarged colon, anemia, infertility, behavioral disorders, reduced intelligence, limb malformations, problems with balance, etc. It all depends on which gene or genes are causing the depigmentation. There are some interesting aspects to hearing problems associated with white markings, especially where the KIT gene is involved. For example, I mentioned that this gene is involved with both spotting and deafness in Dalmatians. However, the incidence of hearing loss in Dalmatians with black patches on the ears is much lower. The KIT gene is also responsible for the white head, belly, feet and tail switch of Hereford cattle, yet I've never heard that deafness is a particular problem for this breed. Note that Herefords have pigmented ears. While I don't know what genes are responsible for the markings of panda bears, I do note that they, also, have pigmented ears. This seems to indicate that genotypes exist that allow pigment cells to migrate to the ear during embryonic development -- resulting in normal hearing -- while restricting migration to the skin and coat sufficiently to produce the white markings that many find desirable. Unfortunately, we don't yet know how this works, though it probably involves some modifier gene(s) that interact with the KIT gene. We also don't know if ferrets are one of the species in which this could be accomplished. (We also don't know how far we could go in eliminating deafness in Dalmatians. Patches are considered a disqualification in the Dalmatian breed standard! Talk about shooting yourself in the foot ...) Behavioral problems associated with depigmentation are another interesting phenomenon, and are related to all types of depigmentation (such as albinism), not just those types caused by a lack of pigment cells. For example, albino mice are known to be much more "emotional" or "reactive" than pigmented mice. Viennese white rabbits are subject to seizures. Pointer dogs suffering from the "nervous behavior" defect tend to be highly depigmented. Holstein cows with large amounts of white are more nervous and less productive. White pigs are more likely to suffer from Porcine Stress Syndrome, which kills them when they are subjected to stress or exertion. (It would be interesting to know just how many of these phenomena are directly related to reduced auditory and/or visual acuity. For example, I don't think anyone ever bothered to check those nervous white Holstein cows to see if they were hard of hearing or had bad eyesight. We certainly know that deaf ferrets require special handling to avoid provoking fear and aggression.) >OK, make that three - What is your personal opinion with regard to the >breeding of these individuals? I, myself, would not. As I see it, there are only two other choices: breed them without regard for health (not very ethical), or embark on a full-scale program to develop healthy strains of marked ferrets (which would involve large amounts of inbreeding and ruthless culling, with all the attendant heartbreak). All for the sake of a characteristic that is of no particular benefit to the animals or the species. Look at all the horrible things that have been done to so many breeds of dog, cat and livestock -- all resulting from breeding programs that treat animals as some kind of artwork to be molded according to some abstract esthetic standard divorced from any concept of biological reality. The responsibility of breeders to consider the well-being of the animal in their selection programs is an aspect of animal welfare that is too often neglected. Too many people who would never consider beating or starving their animals suddenly seem to lose all sense of ethical limits when it comes to breeding them. Temple Grandin at Colorado State University has written quite a bit on this subject, and her articles are well worth the time to read. I recommend the following two for starters: http://www.grandin.com/welfare/genetics.animal.welfare.html http://www.grandin.com/references/horse.genetics.html >While I'm directing these questions specifically at Bob, I'd be really >interested in hearing from anyone who can provide insight! I'd like to hear what Bob thinks of the idea that H. Sapiens actually qualifies as a domestic animal! We may very well have domesticated ourselves before we started on the others. B-) -- Brett Middleton University of Georgia [Posted in FML issue 3406]