Double muscling

The MSTN gene provides instructions for making a protein called myostatin. This protein is part of the transforming growth factor beta (TGFβ) superfamily, which is a group of proteins that help control the growth and development of tissues throughout the body. Myostatin is found almost exclusively in muscles used for movement (skeletal muscles), where it is active both before and after birth. This protein normally restrains muscle growth, ensuring that muscles do not grow too large. Myostatin has been studied extensively in mice, cows, and other animals, and it appears to have a similar function in humans.

At least one mutation in the MSTN gene has been found to cause myostatin-related muscle hypertrophy, a rare condition characterized by increased muscle mass and strength, animals with such mutation are described a “double-muscled”.

These animals do not actually have two muscles, but each muscle is significantly larger than normal. Double-muscled animals have an incredibly muscular look even if they do not exercise. This mutation is of particular interest in species farmed for their meat (like cattle) but can occur in any mammal.

Myostatin mutation is studied in a line of mice called the “Mighty Mouse”. These mice were developed as a side effect of a line of research at the Johns Hopkins School of Medicine when they inactivated or “knocked out” a gene responsible for producing myostatin.

“Mighty mouse” next to common relative.

mightymouse_x600The myostatin mutation is particularly valued in cattle and is a recessive trait often found in the Belgian Blue, Piedmontese, and Marchigiana breeds–but present in many other breeds.

double-muscled-belagian-cows-inbred-for-lean-meat

Confirmed mutation in MSTN found also in the whippet dog breed that results in a double-muscled phenotype known as the “bully” whippet (“A Mutation in the Myostatin Gene Increases Muscle Mass and Enhances Racing Performance in Heterozygote Dogs”, 2007). During this research study were screened also several mastiff type breeds (rottweiler, bulldog, Presa Canario, miniature bull terrier, American Staffordshire terrier, Staffordshire bull terrier, and bullmastiff) without any findings.

Double-Muscled-Whippet

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Research: Gene associated with canine atopic dermatitis

A novel gene associated with canine atopic dermatitis has been identified by a team of researchers led by professors Kerstin Lindblad-Toh, Uppsala university and Ake Hedhammar, SLU, Sweden. The gene encodes a protein called plakophilin 2, which is crucial for the formation and proper functioning of the skin structure, suggesting an aberrant skin barrier as a potential risk factor for atopic dermatitis.

Details appear in the open-access journal PLoS Genetics.

Atopic dermatitis (or eczema) is an inflammatory, relapsing non-contagious skin disease affecting about 10-30 percent of the human population. It is not only humans that suffer from the disease: about 3-10 percent of dogs are also affected. The skin of a patient with atopic dermatitis becomes easily irritated by various allergens such as certain types of food, pollens or house mites. Such irritation causes very strong itching which leads to scratching, redness and flaky skin that becomes vulnerable to bacterial and yeast infections.

To-date, despite many scientific efforts, little has been known about the genetics of the disease. In their study, researchers from Uppsala University, SLU and Broad Institute, compared DNA samples from a large group of German shepherd dogs affected by atopic dermatitis with DNA coming from healthy dogs to reveal the specific DNA segment associated with the disease.

“With the help of pet owners, we have managed to collect a unique set of DNA samples from sick and healthy dogs which allowed us to gain insight into atopic dermatitis genetics,” said first author Katarina Tengvall, Uppsala University.

Purebred dogs such as German shepherds have been selected for specific physical features for several generations. Selection led to an inadvertent enrichment for disease-risk genes in certain breeds. Moreover, the resulting architecture of canine DNA makes it easier to pinpoint segments that carry these disease risk-genes. This helped the researchers to reveal the genetics of atopic dermatitis. They found a region associated with the atopic dermatitis containing the gene PKP-2, which encodes Plakophilin-2, a protein involved in the formation and maintaining of the proper skin structure.

“The finding that certain variants of the PKP-2 gene may increase the risk of developing the disease opens new possibilities in understanding the disease mechanism leading to atopic dermatitis,” continues Katarina Tengvall.

These findings will not only lead to better understanding of the disease, which may lead to better treatment strategies long term. It also opens up the possibilities of development of a genetic test for the disease.

“Our study suggests that plakophilin-2 and an intact skin barrier is important to avoid atopic dermatitis”, says senior author, Kerstin Lindblad-Toh, professor at Uppsala University and Director of SciLifeLab Uppsala. “Another gene involved in the skin barrier has recently been linked to human atopic dermatitis emphasizing the similarity between canine and human atopic dermatitis” continues Kerstin Lindblad-Toh.

Source: http://www.medicalnewstoday.com/releases/260371.php

Research: American dog breeds trace their ancestry to ancient Asia

Once thought to have been extinct, native American dogs are on the contrary thriving, according to a recent study that links these breeds to ancient Asia.

The arrival of Europeans in the Americas has generally been assumed to have led to the extinction of indigenous dog breeds; but a comprehensive genetic study has found that the original population of native American dogs has been almost completely preserved, says Peter Savolainen, a researcher in evolutionary genetics at KTH Royal Institute of Technology in Stockholm.

In fact, American dog breeds trace their ancestry to ancient Asia, Savolainen says. These native breeds have 30 percent or less modern replacement by European dogs, he says.

“Our results confirm that American dogs are a remaining part of the indigenous American culture, which underscores the importance of preserving these populations,” he says.

Savolainen’s research group, in cooperation with colleagues in Portugal, compared mitochondrial DNA from Asian and European dogs, ancient American archaeological samples, and American dog breeds, including Chihuahuas, Peruvian hairless dogs and Arctic sled dogs.

They traced the American dogs’ ancestry back to East Asian and Siberian dogs, and also found direct relations between ancient American dogs and modern breeds.

“It was especially exciting to find that the Mexican breed, Chihuahua, shared a DNA type uniquely with Mexican pre-Columbian samples,” he says. “This gives conclusive evidence for the Mexican ancestry of the Chihuahua.”

The team also analysed stray dogs, confirming them generally to be runaway European dogs; but in Mexico and Bolivia they identified populations with high proportions of indigenous ancestry.

Savolainen says that the data also suggests that the Carolina Dog, a stray dog population in the U.S., may have an indigenous American origin.

Source: http://www.alphagalileo.org/ViewItem.aspx?ItemId=132852&CultureCode=en

Research: Health Implications in Early Spay and Neuter in Dogs

Recent results from research funded by the AKC Canine Health Foundation have the potential to significantly impact recommendations for spaying and neutering dogs in the United States. Most dogs in the United States are spayed or neutered, and for years the procedures have been completed prior to maturity. The study, published in the prominent, open access journal PLOS One, suggests that veterinarians should be more cautious about the age at which they spay and neuter in order to protect the overall health of dogs.

A team of researchers led by Dr. Benjamin L. Hart at the University of California, Davis has completed  the most detailed study performed to date that evaluates incidence of cancer diagnoses and joint problems in one breed — Golden Retrievers — by neuter status: early (before 12 months old), late (12 months or older), and intact. Consistent with previous studies on the topic, the results showed increased likelihood of hemangiosarcoma, lymphoma, mast cell tumors, and canine cruciate ligament (CCL) rupture in neutered dogs.

The most profound observations were in hip dysplasia in male dogs when comparing early and late-neutering. The risk of development of hip dysplasia doubles, and disease occurs at a younger age in the early-neuter group compared to both the intact and late-neuter group. No occurrence of CCL disease was observed in intact male or intact female dogs, or in late-neutered females. In early-neutered dogs, the incidence of CCL was 5.1 percent in males and 7.7 percent in females, suggesting that neutering prior to sexual maturity significantly increases a dog’s risk of developing CCL disease. With respect to cancer, cases of lymphoma were 3-fold greater in the early-neutered males. Interestingly, incidence of mast cell tumors (male and female dogs) and hemangiosarcoma (female dogs only) were highest in the late-neuter group.

“Dr. Hart’s landmark study is the first to provide evidence for when to spay or neuter dogs. For years the veterinary community has been aware that early-spay and neuter may impact orthopedic health in dogs. Through a very detailed analysis and inclusion of body condition score as a risk factor, Dr. Hart was able to show that timing of spay and neuter does indeed have health implications,” said Dr. Shila Nordone, Chief Scientific Officer for the AKC Canine Health Foundation.

“CCL disease is painful, debilitating, and costs dog owners $1 billion annually to treat. The AKC Canine Health Foundation is committed to funding research, like Dr. Hart’s study, that can lead to evidence-based health recommendations. Armed with prudent guidelines for when to spay and neuter dogs we will have a significant impact on the quality of life for dogs,” continued Dr. Nordone.

Importantly, the task at hand is now to determine if the observations in this study are indeed true across all breeds and mixed breeds of dogs. Dr. Hart is interested in continuing his work by studying Labrador Retrievers, German Shepherd Dogs, and Dachshunds. Additionally, gaps in knowledge continue to exist concerning the complex relationship between sex hormones and cancer.

– See more at: http://www.akcchf.org/news-events/news/health-implications-in-early.html#sthash.XBW5GUrK.dpuf