Highlights of FY2005 NIFA Investments in KA301

In fiscal year 2005, NIFA invested approximately $15.8 million in KA301. Below are some of the projects that terminated in 2005. A printable, 2-page color brochure detailing these highlights may also be downloaded.

Bovine Oocyte Activation: The mechanism that the sperm cell uses to turn-on development of the resulting embryo is poorly understood in cattle. Investigators at Utah State University demonstrated that stimulation of an integrin receptor on cattle eggs resulted in the initiation of specific chemical signaling events within the egg that are linked to the initiation of embryonic development. They also identified 19 candidate molecules from the sperm cell that could be involved in fusion of sperm to oocytes or turning-on development in cattle eggs at fertilization. These results will lead to improved methods to control early development of bovine embryos at fertilization. (NRI)

Bovine Oocyte Activation: Characterization of Calcium Responses at Fertilization: Fertilization in mammals is characterized by the initiation of increased calcium oscillations, but how the sperm initiates and sustains the increased release of calcium in the oocyte is not known. Researchers at the University of Massachusetts showed for the first time that intra-cytoplasmic sperm injection (ICSI) fails to induce normal calcium oscillations and may explain why ICSI has not been a successful method of fertilizing bovine oocytes. They also demonstrated that the main calcium receptor (IP3R-1) is the fundamental, and exclusive, receptor mediating calcium oscillations at fertilization. Development of ICSI methods in cattle will lead to new methods of fertilization with sex-selected sperm, generation of transgenic animals, treatment of male infertility, and aid in conservation of endangered species. (NRI)

Early Embryonic Development and Maintenance of Pregnancy in Goats: Embryonic mortality reduces the potential number of animals born by 20-40% and costs sheep and goat producers in Virginia about $1.2 million every year. Research at Virginia State University revealed that the embryo-derived interferon decreased prostaglandin secretion, but this was not related to up-regulation of a prostaglandin metabolizing enzyme. Increased prostaglandin during pregnancy may initiate luteolysis and reduce progesterone output by increasing production of endothelin-1 and inhibiting insulin-like growth factor-1. A better understanding of the role of prostaglandins, uterine function, and embryo development may lead to new methods to reduce embryonic mortality. (Evans-Allen)

Microfluidic Systems for In Vitro Production of Bovine Embryos: Scientists at Vitae LLC designed and constructed a microfluidic device capable of supporting all stages of in vitro embryo production, from oocyte maturation through blastocyst formation. The microfluidic device demonstrated equal or improved development of bovine oocytes to blastocysts as compared to traditional methods of embryo production. The ability to perform multiple in vitro embryo production processes within a single device provides the basis for future automated, high throughput systems that could allow unprecedented scientific research on bovine embryo production. (SBIR Phase I)

Use of GnRH-PAP for Chemical Sterilization: Investigators at Colorado State University conjugated gonadotropin-releasing hormone (GnRH) to pokeweed antiviral protein (PAP; a powerful cytotoxin) for chemical sterilization. They also developed an assay to recognize both GnRH and PAP. In rams, serum concentrations of testosterone and LH as well as testicular functions were suppressed for at least 24 weeks after treatment with GnRH-PAP. Nonsurgical sterilization technology may provide livestock producers a more humane method for sterilization than surgical castration and may also be used to control the population of wildlife (such as deer and elk) that impact the carrying capacity of Western ranges. (NRI)

Gene Expression in the Peri-Implantation Porcine Conceptus and Endometrium: Investigators at Oklahoma State University determined that porcine conceptuses secrete interleukin-1 beta during the period of trophoblast elongation. These results provide new clues regarding how the uterus regulates a proinflammatory response to establish pregnancy in pigs. Estrogen secretion by developing conceptuses may serve to modulate the endometrial response to the release of interleukin-1 beta from the conceptus to regulate cytokine secretion and the inflammatory reaction of the uterus during implantation. Understanding the role of estrogen and interleukin-1 beta in the uterus will provide a pathway to control the estrous cycle and possibly influence growth and survival of pig embryos. (Hatch)

Alpha-2-Macroglobulin Regulates Estradiol Production: Scientists at Michigan State University demonstrated that alpha-2-macroglobulin is a highly specific potent stimulator of aromatase activity and estradiol production by ovarian granulosa cells. Amounts of the alpha-2-macroglobulin receptor were inversely associated with intrafollicular concentrations of estradiol during growth of dominant follicles. Thus, alpha-2-macroglobulin and its receptor have autocrine and/or paracrine roles important for regulation of estradiol production and growth of dominate ovarian follicles in cattle. This new information may be used to design new methods to control fertility in cattle. (NRI)

The Insulin-Like Growth Factor System and Stallion Infertility: Male factor infertility in successful equine athletes contributes to substantial reductions in the multi-billion dollar equine breeding industry. Scientists at the University of Florida demonstrated that during sexual rest, stallions having higher seminal plasma insulin-like growth factor (IGF-1), more IGF binding protein-2 per ejaculate, more morphologically normal sperm, and higher first cycle pregnancy rates. During sexual activity, stallions having higher seminal plasma IGF-1 had a lower number of cycles per pregnancy. Thus, the relationship between IGF-1 and fertility provides new information regarding the role of IGF-1 in seminal plasma and subfertility in stallions. (Animal Health)

Gene Expression Affects Male Fertility in Poultry: Intensive selection for growth rates has resulted in low fertility in chickens and turkeys. An NRI Research Career Enhancement Award was made to an investigator at the University of Arkansas to provide training in new molecular biology approaches and to characterize the spermatogonial degenerative dysfunction (SDD) gene in roosters. Using these new technologies the SDD gene was mapped to a 4 mega base pair region of chicken chromosome 7. The SDD trait is readily identifiable in commercial breeding stock and may affect more than 50% of the males in some lines. Thus, low male fertility due to sperm degeneration and sperm mobility can be addressed through marker assisted selection. A genetic test for this condition is being developed for use in the poultry breeding industry. (NRI)

Enhancing Reproductive Efficiency in Swine Operations that Utilize Artificial Insemination: The efficiency and profitability of swine operations utilizing artificial insemination may be limited by: 1) boars from which it is difficult to collect semen and 2) the inability to synchronize estrus in replacement gilts (which may comprise up to 50% of the swine herd). Scientists at Virginia Polytechnic Institute demonstrated that intramuscular injections of prostaglandin enhanced sexual behavior and expedited the training of young boars to mount an artificial sow and allow semen collection. Prostaglandin treatment also restored normal libido in boars suffering from suppressed sexual behavior due to low blood levels of testosterone and estradiol. Prostaglandin had no negative effects on semen quality. In prepubertal or mature, cycling gilts strategic use of an orally active progestin synchronized estrus. Administration of gonadotropins at 24 hours after progestin withdrawal increased ovulation rate and thus, the potential litter size from each gilt. These new management strategies will be used to enhance reproductive efficiency and profitability in swine operations that use artificial insemination. (Hatch)

Enhancing Reproductive Performance of Heat-Stressed Dairy Cattle: In tropical and subtropical environments dairy cattle are exposed to heat stress throughout most of the year which results in low fertility and decreased milk production. Members of the S-299 multi-state committee are trying to develop physiological, nutritional, and environmental strategies to enhance milk production, reproductive performance, profitability, and heat tolerance of dairy cattle in a hot, humid climate. Investigators at the University of the Virgin Islands demonstrated that heifers with more than 50% black hair coat had a lower pregnancy rate than heifers with less than 50% black hair coat. The surface temperature of heifers with black hair coat was 4 o C higher than that of heifers with white coats. Thus, selecting for light colored dairy cattle may be a way of mitigating effects of heat stress in dairy cattle in hot and humid climates. (Hatch)

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