The newsletter of HorseHobbyist.com Winter 2004 In This Issue:
BRRRRR It's cold!!!! There is no doubt that Old Man Winter had quite a say in the weather here recently. What with snowdrifts that are taller than me and days that max out in the lower single digits, the Bahamas are sounding better and better as the days go by! Despite the cold temps, though, the horses have to be fed and watered and life still goes on. Foaling season has begun for some, but for many of us, we're still watching those mares growing bigger and bigger, and hoping time will go by a little quicker for reasons other than wishful warm weather dreams! Winter is a good planning time too. Just as gardeners sit and plan out their planting season, we horse owners tend to sit by the fire with our breed journals, local equine periodicals, and of course, the left-over Christmas catalogs from our favorite tack shops and dream about the year ahead. For some of us, we're looking at potential breedings to our mares, as well as thinking about what kind of foals we'll be getting this year. Show folks are thinking about the show season ahead, getting that winter coat off and our show horses in shape (as well as maybe a few pounds off our own girth), and thinking about what to wear this year to wow the judge. Some may be planning which trails to take off for a camping trip , or when their next big barn party will be. We aren't the only ones making plans, though! Many breed organizations, saddle clubs, and regional groups are also putting together the year ahead for their members. New rule books from our breed organizations are being sent out to members, flyers are starting to appear in the mail for future clinics and shows, and in general, there's a bit of a buzz starting over again that will lead into another year in the world of horses. One of the louder buzzes within the stock breeds right now is one that the AQHA has started, as they seek to eliminate horses with the genetic disorder known as Hyperkalemic Periodic Paralysis, or HyPP. It's a very controversial and hot topic with valid concerns on both sides of the issue. With a test that can determine horse with the genetics for HyPP, many feel the best thing would be to eliminate those horses entirely from the breeding stock. On the other side of the fence are those with investments of time, money, and (dare I say it in reference to business) love in those horses with the genetics who for various reasons, desire foals from those horses. Needless to say, there are no easy answers. The whole issue stirs up some very interesting perspectives from the equine world, some of which involve how much we do or don't know about genetics. I've touched on some very basic stuff here in my article "Gene Soup," as well as in an article printed with permission from the Equine Disease Quarterly that sums up some serious work done by various geneticists and veterinarians. Who knew there was so much going on behind the scenes in the field of genetics? Who knows, maybe one day we'll be picking up those catalogs and ordering a custom genetically perfect horse!
PH Cody
Attention HorseHobbyist fans! We need your help! We are looking for a few good hosts to help monitor boards and chats here at HorseHobbyist. Hours are flexible, benefits include a wonderful group to be associated with and the opportunity to help create a great internet spot for everyone! For information... PetHobbyist.com Volunteer Information and Application Currently featured on the HorseHobbyist message boards:
Horses in the News PHMark keeps you updated on the latest equine news! You can check it out online,or sign up to have horse news sent to your email box - it's free from HorseHobbyist.com! Just visit HorseHobbyist News.
Our chat system is all new! Come check out our BRAND NEW Paddock Chat Room, and log in with your username and password. If you are not already a registered user of the site, registration is not required - simply go to chat.pethobbyist.com and use the "Guest" log-in option, then select The Paddock as your chat room. There is nothing to download or install, but the system does require you to have java enabled in your browser settings. If you have questions or problems, please visit our Chat Help Area.
What are "genes" anyway? Why are they so important? And why are so many researchers totally devoted to them? Genes are specific regions that make up chromosomes (strands of DNA), which in turn determine who, or what, we are. In simple terms, the information stored in our genes is the blueprint for everything our body is and does. There are approximately 1000 genes per chromosome, and humans carry 46 chromosomes. If you're thinking that that's a lot of genes, look at horses, who carry 64 chromosomes. But even horses don't hold a candle to a chicken's 78 chromosomes. No wonder genetic research is so complicated! Each cell in a body contains a full copy of all those chromosomes and therefore, all those genes. It gets even more complicated when you start looking at what genes can do. Some genes can cause a significant, visible trait all by themselves, or with only a few genes involved. This is known as a "qualitative trait." Other traits, known as "quantitative traits," depend on several genes. For instance, basic coat color traits in horses are "qualitative" and rely on very few genes to be expressed. If a horse carries what is known as the E gene (instead of the e gene), the horse will be black - or some modified form of black depending on other genetics. Something like growth rate would be classified as a "quantitative trait" because it would rely on several different genes working together. That's all fine and good, but nature is never that simple, is she? Genes can sometimes, well, mess up. A protein combination that makes up part of the gene might get switched, or sometimes even left off. Worse, when this happens, and the cell containing that genetic mutation reproduces itself, you start having more of that mutation. In an already developed body, where the various cells have already differentiated into specialized fields, like skin cells, or muscle cells, this is often not a problem. In fact, the body often recognizes these mutations as mistakes, and destroys them. It's not a perfect system by any means, as things like cancer are usually the result of such genetic goof ups! But it's when the original mutation occurs early on in an embryo and therefore is found in all the cells of that baby's body that there is potential for a real problem. Worse, if it's not obvious or problematic to the baby, it will be passed on to its offspring. Now, before we go too far, mutations aren't always harmful, despite the negative connotations to the word! For example, if you have a horse with unique color patterns, that can sometimes be a result of a mutation of some genetic code along the way. Animals have evolved through genetic mutations that made survival easier for their descendents. There's a middle ground, too. Some mutations and gene combinations cause problems but at the same time help in other areas. For instance, sickle cell anemia in humans can cause all kinds of problems, but it also makes its carrier resistant to the deadly mosquito-borne disease, malaria. Other mutations or gene combinations aren't as innocent. For instance, in Paints there are foals born almost totally white who also have incomplete gastointestinal tracts. This is known as Lethal White Syndrom and is attributed to a combination of a recessive gene which only "acts" this way when it is combined with another of the same gene. Science is slowly but surely trying to crack the genetic codes so that not only can we detect these mutations and gene combinations that cause genetic diseases, but also maybe one day correct them. Time will tell how successful they'll be as far as horse breeding goes. There is certainly plenty being studied, and so much more still untouched. Travis Yates, DVM, contributed to this article.
South Africa's Kruger National Park was the center of the horse genome project as the Fifth International Equine Gene Mapping workshop was convened by the Dorothy Russell Havemeyer Foundation from August 11-14, 2003. Previous meetings have been held in Lexington, Kentucky (1995); San Diego, California (1997); Uppsala, Sweden (1999); and Brisbane, Australia (2001). Thirty-five scientists from Australia, New Zealand, Japan, Korea, California, Texas, Kentucky, New York, the United Kingdom, France, Norway, Poland, the Czech Republic, Italy, and South Africa presented their research and discussed ways to develop and use the gene map for the benefit of the horse. This workshop was unique in the series because it was the first in which a majority of the presentations dealt with applications of genomics to health problems. Presentation topics included inflammatory diseases, developmental bone diseases, arthritis, respiratory disease, exercise-induced pulmonary hemorrhage, male infertility, sarcoid tumors, and immunity. Specific inherited traits also discussed included the angiotensin-converting enzyme (ACE) gene for performance, lavender foal syndrome, hereditary equine regional dermal asthenia (HERDA), degenerative suspensory ligament desmitis, and mapping the gene for Appaloosa coat color patterns. In a broad sense, the topics of the workshop included hereditary and non-hereditary conditions that are influenced by altered gene expression. Indeed, the legitimate topics of the workshop include performance, fertility, and health. Colic and laminitis are important diseases of horses that are characterized by inflammation. The research group from the University of Georgia directed by Jim Moore is characterizing thousands of genes expressed in leukocytes with special emphasis on those expressed in response to lipopolysaccharides, a mediator of inflammation. Immunology is also a popular target of research. Petr Horin (Czech Republic), Loren Skow and Ashley Gustafson (Texas A&M), and Doug Antczak (Cornell University) reported characterizing gene expression as well as hereditary variants and genomic structure of the immune system. Joie Watson (UC Davis) reported studies on the gene IL4R and its possible relationship to recurrent obstructive airway disease in horses, and Cindy Harper (University of Pretoria, South Africa) reported a large epidemiological study on exercise-induced pulmonary hemorrhage in Thoroughbred horses. Jamie MacLeod (University of Kentucky) reported on functional genomic approaches to studying musculoskeletal diseases. These complex studies are beginning to show results but will benefit greatly from further development of genomic tools for the horse. Other studies focused on specific traits or specific candidate genes. Work continues to map and find the genes for lavender foal syndrome of Arabian horses (Broad at Brisbane, Australia/Antczak at Cornell/Penedo at UC Davis), suspensory ligament desmitis of Peruvian Pasos (Cothran at Kentucky), and HERDA (Bannasch at UC Davis). Work was reported by Natasha Ellis of Sydney, Australia, on performance and the ACE gene. Genetic variants had been found but so far none associated with improved performance. Bhanu Chowdhary and Terje Raudsepp (Texas A&M) and Gabriella Lindgren (Stanford University and Uppsala University, Sweden) described studies on the horse Y chromosome with the goals of identifying effects on male infertility. Work in Kentucky (Rebecca Terry, University of Tampa) led to mapping the gene for Appaloosa coat color to horse chromosome 1. The specific gene responsible for the color trait remains to be identified. A recurrent theme within these reports was the need for improved genomic tools in order to achieve goals effectively and more rapidly and economically. In this connection, three comprehensive maps were unveiled during the meeting. Matthew Binns and June Swinburne (Animal Health Trust, United Kingdom) reported progress towards a linkage map with more than 700 markers covering all horse chromosomes. Domenico Bernoco (Stormont Labs and UC Davis) demonstrated that the linkage maps produced in different studies could be joined together in a comprehensive single map. Bhanu Chowdhary and Terje Raudsepp (Texas A&M) presented a framework map of 750 markers based on a radiation hybrid panel. Other scientists reported the addition of microsatellite markers to linkage and radiation hybrid maps (most participants), creation of new markers (Hasegawa, Japan), mapping markers to chromosomes (Teri Lear, Kentucky/Chowdhary and Raudsepp, Texas A&M) and projects to construct comprehensive maps using large insert DNA clones (Gerard Guerin, INRA, France/Tosso Leeb, Germany) preparatory for whole genome sequencing. Workshop participants set new goals for the next two years that included tripling the number of mapped genes and DNA markers, creating new tools to investigate gene expression, and building a scaffold for whole genome sequencing of the horse. So when will the map be completed? It is. We are using it while continuing to improve its resolution and usefulness. A Web site describing the workshop activities and the accomplishments in detail can be found at www.uky.edu/AG/Horsemap. For more information, contact Dr. Ernie Bailey, 859-257-4757, ebailey@uky.edu, Department of Veterinary Science, University of Kentucky, Lexington, Kentucky. This article was reprinted with permission from Equine Disease Quarterly.
|
| © OnlineHobbyist.com, Inc. |
