Fighting Mastitis.........An Udder Success

Mastitis is a disease of the mammary gland caused by pathogens that find their way into the lumen of the gland through the teat canal. Mastitis is a very efficient disease as it is able to transfer from cow to cow. As antibiotics are only effective in 15% of mastitis cases, scientists have had to develop a new method of fighting this disease. A solution to this antibiotic resistance includes, transgenic cows that produce milk containing an antimicrobial protein called lysostaphin. 30% of all mastitis cases are caused by Staphylococcus aureus.
As milk is used for human consumption and many products are made from it, ongoing research has had to be taken into account. Overall lysostaphin in milk does not appear to be a major concern to human or cow’s health, but is a sensitive issue.

Researchers have found that approximately 71% of cows that were non-transgenic became infected by Staphylococcus aureus, whereas only 14% of transgenic cows became infected. From this research it would soon become relevant to use transgenic cows as they would save money, time and resources. This genetic breakthrough will have a major benefit on the dairy industry, not only on a national scale but on a global scale.

Primary Resource:
Wall, R.J., Powell, A.M., Paape, M.J., Kerr, D.E., Bannerman, D.D., Pursel, V.G., Wells, K.D., Talbot, N. and Hawk, H.W., 2005. ‘Genetically enhanced cows resist intramammary Staphylococcus aureus infection’, Nature Biotechnology 23, pg 445-451.
http://www.nature.com.ezproxy.library.uq.edu.au/nbt/journal/v23/n4/full/nbt1078.html

Donovan, D.M., Kerr, D.E., Wall, R.J., 2005. ‘Engineering disease resistant cattle’, Department of Animal Science, University of Vermont, Burlington

http://www.springerlink.com/content/u1m28j7732815g68/fulltext.pdf
Bliss R.M., 2005. Transgenic Cows Resist Mastitis-Causing Bacteria, U.S. Department of Agriculture.
http://www.ars.usda.gov/IS/pr/2005/050404.htm
Rainard, P., 2005. Transgenic cows expressing an antibacterial endopeptidase in their mammary glands show enhanced resistance to mastitis, Nature Biotechnology 23, pg 430- 432
http://www.nature.com.ezproxy.library.uq.edu.au/nbt/journal/v23/n4/full/nbt0405-430.html
Written by: Callan Cribb

Time to Cluck Bye to Salmonella

Concern for use of antibiotics in animal production soars sky high and once again, scientists are scratching their heads and trying to develop new ways for combating the never ending battle between human & animal health and the air-borne pathogen, salmonella.

The trend against antibiotics is steering scientists down a new and exciting path; a path that has opened new doors for chicken selection producers. This may mean that salmonella will no longer pose such a prominent threat in our food chain and production systems.

The detection of salmonella in chickens is both costly and difficult. Along with being an extreme health hazard, the eradication of salmonella is of a very high priority. The push for breeding of salmonella-resistant chickens is of great importance and many studies are currently underway with the aim of pin-pointing either traits on specific chromosomes or potentially gene expression involved in resistance.

In one particular study, chicken progeny where examined from an inbred population of one line of chickens. It is suggested that the substitution of a nucleotide in the DNA resulted in an amino acid change. This discovery is considered evidence of the fact that chickens inherit the complex trait which inhibits the infection of Salmonella tryhimurium.

Selection for salmonella-resistant chickens will not only increase the health of production populations, but will also reduce the potential entry of disease-causing bacteria in our food chain and production systems. However scientists are still making new discoveries and it will only be a matter of time before we will be able to cluck bye to salmonella.

Written by 41777574

References:Iowa State University Animal Industry Report 2005, Genes for Resistance to Salmonella in Poultry, viewed 27 June 2008, http://www.ans.iastate.edu/report/air/2005pdf/2017.pdf.

INRA press service 2005, Breeding of salmonella-resistant chickens, viewed 27 June 2008, http://www.international.inra.fr/press/salmonella_resistant_chickens.

Genome Research 1997, ‘Resistance to Salmonellosis in the Chicken Is Linked to NRAMP1 and TNC’, Genome Reserch, Cold Spring Harbor Labratory Press, vol. 7, pp. 693-704

Man’s Best Friend Close to our heart.

Can man’s best friend lead the way in cardiac research.

Researchers at the Cardiovascular Research Institute at the NY College of Medicine have shown that dogs injected with stem cells can heal their hearts after the block of one of the arteries that transports blood to the heart. If arteries supplying the heart are blocked they cause a lack of oxygen to the heart muscles and this leads to the tissue damage and death this tissue, this is also known as a myocardial infarct and is one of the leading causes of heart disease.

Using canine stem cells, more specifically cardiac stem cell this study has shown that repair of the damage caused by a myocardial infarct is reversible. By occluding the left coronary artery to induce tissue damage (which seems “slightly” un-ethical) and then injecting cardiac stem cells adjacent to myocardial infarct, the study observed marked improvement of function and repair of the damaged tissue. These stem cells were selected on specific markers that are found in stem cells, after selection these stem cells were grown and then injected.

This is an exciting area of research that can bring about great amounts of insight not only into stem cells but also into the treatment myocardial infarcts after they have occurred.

Primary Source
http://www.pubmedcentral.nih.gov/picrender.fcgi?artid=1157041&blobtype=pdf

Swab a Scotty

Humans and various dog breeds are victims of von Willebrand’s disease (vWD), which is a hereditary bleeding disorder. The disease is caused by a defect of the clotting factor von Willebrand factor (vWF) and is characterised by serious bleeding episodes that are often fatal. There are three types of vWD, type three is the most severe form, described by the complete absence of vWF in the blood of homozygous affected individuals, and in reduced amounts in heterozygotes. Scottish terrier’s are primarily affected by this type of the disease with the prevalence estimation among the species being 18% to 30%. This type of Von Willebrand’s disease is an autosomal recessive trait and because of genetic investigations can now become a disease of the past for Scottish terrier breeders, with the development of a DNA test to detect both homozygous affected dogs and heterozygous carriers that requires a simple swab of cheek cells. Type three vWD in Scottish terriers is remarkably similar to the type three in human vWD sufferers which plays a key role in this veterinary advancement.

To develop the test, infected vWD tissue was obtained and through polymerase chain reaction (PCR), using primers sequenced from human genes, the complete amino acid sequence of that deoxyribonucleic acid (DNA) was derived. Amplification identified the single base deletion responsible for vWD in the Scottish terrier. Researchers used this concise identification to create a mutation based DNA laboratory test. Apart from the direct benefits to dog breeders, this development is one of significance, as it incorporates human genomics into veterinary treatment.


Key References:

Venta, P.J., Li, J., Yuzbasiyan-Gurkan, V., Brewer, G.J., Schall, W.D., 2000. Mutation causing von Willebrand’s disease in Scottish terriers. Veterinary Internal Medicine Journal 14, 10.

Patterson, D.F., 2000. Companion animal medicine in the age of medical genetics. Veterinary Internal Medicine Journal 14, 1.

Elizabeth Hoffman

Forget about the apple, an egg a day may keep the doctor away!!

There is a brighter future ahead when it comes to cancer treatment and it could be as simple as eating an egg. Researchers at the Roslin Institute in the United Kingdom, you might remember it as the birthplace of Dolly the sheep, have genetically engineered chickens to lay eggs that contain proteins that fight cancer in the egg whites. A number of companies have spent millions of dollars developing the proteins that target and eliminate tumour cells. Bacteria and even goats and rabbits have been used in the attempt to mass produce these therapeutic proteins with little success.
Chickens could be the answer, with their high reproductive rates and egg laying capabilities. The reliability of the chickens producing the anti-cancer proteins has been a difficult obstacle. This problem was overcome by injecting viruses into the embryo through tiny holes in the eggshell. The virus contained genetic sequences which coded for either the protein miR24 which is a cancer-fighting antibody or an antiviral protein human interferon beta-1a. These are used to fight malignant melanoma and multiple sclerosis.
Chicks produced in this way pass on these genes to the next generation after reaching adulthood. The proteins were found in the eggs that were laid by the females. Anticancer antibodies if produced throughout the body can be harmful to the chicken, but the gene expression has been limited to the oviduct at the site of egg white production.
Don’t start cracking eggs just yet. Although the therapeutic protein can be extracted in commercially viable amounts, testing on human effectiveness is still the next step, and eating an anticancer egg could be many years away.

Primary References:
Lillico, S.G., Sherman. A., McGrew, M.J., Robertson, C.D., et al. (2007). Oviduct-specific expression of two therapeutic proteins in transgenic hens. Proceedings of the National Academy of Sciences USA 104, 1771-1776.
Wayman, E (2007). Barnyard Pharmaceuticals. Science NOW Daily News 6 January. http://sciencenow.sciencemag.org/cgi/content/full/2007/116/4

Secondary References:
Lewcock, A (2007). Protein production in chicken eggs cracked. http://www.in-pharmatechnologist.com/news/ng.asp?id=73404-viragen-oxford-biomedica-roslin-institute-protein-transgenic

Would you like diabetes with that dog today?

http://www.blackwell-synergy.com/doi/pdf/10.1111/j.1748-5827.2007.00398.x

An estimated one out of 500 dogs are diagnosed with canine diabetes, a condition caused by a deficiency in insulin. Certain breeds of ‘man’s best friend’, like the Labrador and Beagle, have a greater risk of developing this condition whilst some breeds, such as the German shepherd, have a naturally lower risk of inheriting the disease. Why is this?

Genetics is now explaining why such a separation exists by applying knowledge from human genetics. Canine diabetes is best illustrated as the equivalent of type 1 diabetes in humans. This association allows for a basis for genetic research to further understand the reasons for different susceptibility levels amongst the breeds of dogs in regard to diabetes mellitus.

Genes looked at in humans to determine susceptibility (major histocompatibility complex genes, MHC ) have an equivalent in canines (dog leucocyte antigen genes, DLA). Diabetic dogs and breeds within the diabetes-susceptible category have a strong association with a common haplotype (group of alleles of linked genes) of these genes. Another haplotype has a presence significantly reduced in diabetic dogs compared to non-diabetic dogs which suggests a protective characteristic.

Selective breeding in dogs has lead to a restricted DLA gene pool in many breeds which accounts for the strong distinction between diabetes-susceptible breeds and diabetes-resistant breeds and this predisposed nature should be acknowledged by veterinarians and owners alike.

Primary Reference
Catchpole, B., Kennedy, L.J., Davison, L.J. and Ollier, E.R. 2008.

Canine diabetes mellitus: from phenotype to genotype. Journal of Small Animal Practice. 49, 4-10.

Secondary references

Basic information of canine diabetes mellitus:
Canine Diabetes n.d., Intervet Schering-Plough Animal Health, viewed 23 May 2008, <

http://www.cat-dog-diabetes.com/dogs-diabetes-mellitus.asp

>

Definitions and explanations:

Type 1 Diabetes:
Type 1 Diabetes 2006, International Diabetes Institute, viewed 26 May 2008, <http://www.diabetes.com.au/diabetes.php?regionID=236>

Major Histocompatibility Complex:
Histocompatibility 2008, Medical Microbiology, viewed 26 May 2008, <http://www.cehs.siu.edu/fix/medmicro/mhc.htm>

Haplotype:
Haplotype 2008, Wikipedia, viewed 23 May 2008, <http://en.wikipedia.org/wiki/Haplotype>

Student ID: 41753233

Bite me: Let’s save the dogs!

Currently, 130000 dogs are euthanized in Australia as a result of abandonment in animal shelters (2). Two paramount factors which are of importance are aggression and mass production of litters. Genetics can make a difference to these atrocious statistics.
Lindblad-Toh, K, et al. (2005), have covered nearly 99% of the dog genome. They sampled 10 different dog breeds as well as other canine species resulting in the discovery of 2.5 million individual genetic differences among these breeds. These differences, single nucleotide polymorphisms (SNPs) are utilized in determining ‘signposts’ that can be used to locate the genetic contributions to physical and behavioral traits as well as disease (1).
Additionally the discovery of selective breeding carrying large genomic regions of several million bases of DNA into breeds, called ‘haplotype blocks’, making it much easier to find the genes responsible for behavior (also disease and body size).
SNPs and large genomic regions will help in identifying aggressive and large litter size genomes. Once the genomes are isolated then the genes from that particular genome can be identified and also the protein associated with that gene. This opens multiple avenues of stopping that particular trait from continuing. Additionally, the genes for non aggressive and small litter size must be dominant (3) and a coat colour marker should be used. Once it is, then these genes should be included into the genetic pool so it can be passed to the next generation. Hopefully in time dog abandonment, over population and aggression can be stopped.

References:
Primary:
1. Lindblad-Toh, K, et al. (2005). Genome sequence, comparative analysis and haplotype structure of the domestic dog. Nature 438, 803-819.

Secondary:
2. www.saynotoanimalsinpetshops.com/faq.html
3. www.bowlingsite.mcf.com/GENETICS/colorGen.html
Useful website:
4. www.workingdogs.com/genetics.htm

BY: Candice McKeone- Taylor. 40096559