DRUM Community: Animal & Avian Sciences

GENOME-WIDE ANALYSIS OF CHICKEN MIRNAS AND DNA METHYLATION AND THEIR ROLES IN MAREK'S DISEASE RESISTANCE AND SUSCEPTIBILITY

2013-02-15T03:30:45Z

Title: GENOME-WIDE ANALYSIS OF CHICKEN MIRNAS AND DNA METHYLATION AND THEIR ROLES IN MAREK'S DISEASE RESISTANCE AND SUSCEPTIBILITY Authors: Tian, Fei Abstract: Marek's disease (MD) is a T cell lymphoma in chickens and causes high mortality and morbidity in productive chickens. Two inbred chicken lines, resistant line 63 and susceptible line 72, with the same MHC haplotype, showed distinct disease outcomes after MDV infection. The current studies aimed to illustrate the role of microRNA (miRNAs) and DNA methylation in MD resistance and susceptibility in chickens. First, to ascertain the function of miRNAs, miRNA microarray experiments were used to identify miRNAs sensitive to MDV infection in the 2 lines. Most miRNAs were repressed in line 72 after MDV infection, while their transcription was steady in line 63. The miRNA target genes were identified in chickens. Cellular miRNA gga-miR-15b and gga-let-7iwere reduced in infected line 72 chickens and MD tumors. The downregulation of the two miRNAs increased the expression of ATF2 (activating transcription factor 2) and DNMT3a (DNA methyltransferase 3a) in infected line 72. These results indicated that miRNAs may play antiviral functions through modulating target gene expression. Next, to characterize the role of miRNAs in MDV infection, the selected chicken miRNAs were overexpressed in MDV infected DF-1 cells. The overexpressions of chicken miRNA gga-miR-15b and gga-let-7i, by using the retroviral based vector, significantly restricted MDV replications in vitro. MDV oncoprotein was repressed, suggesting that chicken miRNAs may limit MDV propagation. Finally, we found deregulation of transcription of DNA methyltransfereases (DNMTs) in lines 63 and 72 after MDV infection, which coordinated with the methylation alterations in the 2 lines. Infection induced differential methylation regions (iDMRs) that were identified through genome-wide DNA methylation quantification. Genes overlapping line-specific iDMRs were related with pathways of different functions in these two lines, implying the involvement of DNA methylation in MD- resistance and susceptibility. An in vitro study showed that DNA methylation inhibitor repressed viral spread and viral replication. In conclusion, the observed variations of miRNA expression and DNA methylation may be associated with disease predisposition in chickens.

FUNCTIONAL INSIGHTS INTO HRG-1-MEDIATED HEME TRANSPORT

2013-02-07T04:04:57Z

Title: FUNCTIONAL INSIGHTS INTO HRG-1-MEDIATED HEME TRANSPORT Authors: Yuan, Xiaojing Abstract: Heme is an essential cofactor involved in various biological processes including oxygen transport, xenobiotic detoxification, oxidative metabolism, gas sensing, circadian rhythm, signal transduction, microRNA processing and thyroid hormone synthesis. Heme is also an essential nutrient for parasites and is the major dietary iron source for humans. Despite our extensive understanding of the mechanisms of heme synthesis and degradation in eukaryotes, little is known as to how heme is transported and trafficked in eukaryotes. Recently, CeHRG-1 and CeHRG-4 were identified as the first bona fide heme importers/transporters using the heme auxotroph, Caenorhabditis elegans. To gain mechanistic insights into the heme transport function of HRG-1-related proteins, we conducted a structure-function analysis of CeHRG-1 and CeHRG-4 by exploiting yeast mutants that are genetically defective in heme synthesis. Our studies reveal that HRG-1-related proteins transport heme across membranes through the coordinated actions of strategically placed amino acids that are topologically conserved in both, the worm and human proteins. To further dissect the functional elements that dictate their intracellular localization, we generated a series of chimeras by swapping the amino and carboxy terminal segments of CeHRG-1 and CeHRG-4. Our analysis in yeast and mammalian cells demonstrate that the C-terminal domains are essential for membrane localization of the protein, while the N-terminal domains are important for proper function, and plausibly multimerization of HRG-1-related proteins. Currently, there are no pharmacological means to aid in the study of the cellular and physiological roles of eukaryotic heme transporters. We, for the first time, developed and executed a high-throughput screen of 233,360 compounds, to identify potential antagonists of HRG-1-related proteins by utilizing parasite heme transporters as the primary screening bait. Subsequent study in parasites will provide novel drug candidates against helminths that infect humans, livestock, and plants, as well as against genetic disorders of heme and iron metabolism in humans. Taken together, results from our studies will significantly advance novel functional and therapeutic insights into HRG-1 mediated heme transport in health and disease.

DEVELOPMENT OF ALZHEIMER'S-LIKE PATHOLOGY IN NON-HUMAN PRIMATES WITH REDUCED LEVELS OF NOREPINEPHRINE

2013-02-07T03:43:27Z

Title: DEVELOPMENT OF ALZHEIMER'S-LIKE PATHOLOGY IN NON-HUMAN PRIMATES WITH REDUCED LEVELS OF NOREPINEPHRINE Authors: Duffy, Kara Beth Abstract: Synthesis of the norepinephrine distributed to sub-cortical and cortical brain regions occurs in the locus coeruleus. Impaired function results in reduced availability of norepinephrine. Locus coeruleus degeneration is a well-documented feature of Alzheimer's disease; however, the role of catecholaminergic dysfunction remains unclear. Deregulation of this system may accelerate the development and progression of Alzheimer's disease, particularly in patients without familial gene mutations. Currently no animal model exists for idiopathic Alzheimer's disease, which accounts for the majority of human cases. To ascertain the role of the noradrenergic system on the development of amyloid pathology and amyloid-β synthesis pathway, female non-human primates received injection of 40 mg/kg of the neurotoxin DSP4 (N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine) or vehicle and subsequent injections three and six months later (10 mg/kg DSP-4). At nine months, brain samples were processed for catecholamines. Distribution of amyloid identified by 6E10 and localization of dopamine β-hydroxylase to visualize locus coeruleus neurons was examined using immunostaining in tissue sections. Brain levels of amyloid precursor protein, soluble amyloid-β peptides (1-40 and 1-42) along with β-site APP cleaving enzyme-1 were also measured. Results showed norepinephrine depletion in the locus coeruleus following DSP4 injection. Reduction of dopamine β-hydroxylase was detected in aged rhesus monkeys after DSP4. Distribution of amyloid identified by 6E10 was exacerbated in squirrel monkeys following DSP4 and elevated in aged rhesus monkeys after DSP4; additionally DSP4 increased the amyloid-β42 to amyloid-β40 ratio in aged rhesus monkeys. Species specific alterations in amyloid precursor protein and β-site amyloid precursor protein cleaving enzyme-1 were observed and rhesus monkeys were more sensitive to effects of DSP4. These data provide evidence for a potential mechanism important in Alzheimer's disease pathology development and indicate that decreased norepinephrine contributed to an increase in soluble amyloid isoforms and increased accumulation in neocortex in non-human primates. Altered amyloid precursor protein processing contributes to increased amyloid pathology in the absence of chronic neuroinflammation. Non-human primates are an ideal candidate for an animal model because amyloid pathology and neurodegenerative disease characteristics occur naturally later in life, similar to humans.

THE IMPACT OF CULTURE MEDIA ON THE IN VITRO PRODUCTION OF CAT BLASTOCYSTS AND EXPLANT QUALITY

2013-02-06T03:31:54Z

Title: THE IMPACT OF CULTURE MEDIA ON THE IN VITRO PRODUCTION OF CAT BLASTOCYSTS AND EXPLANT QUALITY Authors: Nestle, Emily Abstract: Continued improvements in embryo culture media composition allow for the growth of high quality blastocysts, which can be used to derive embryonic stem cells (ESCs). ESCs are capable of becoming any cell type in the body making them a valuable research tool for therapeutic and regenerative research, while furthering our understanding of embryonic development and cell differentiation. The domestic cat is an important model species for both human medicine and wild felids. Cat embryo culture produces blastocysts at a rate far below that of the mouse and initial attempts at deriving cat ESCs have resulted in embryonic stem-like cells, which cannot be maintained indefinitely. In this study we assessed and compared the quality of cat blastocysts produced in vitro using two commercial human blastocyst growth media, and the maintenance of pluripotency markers OCT-4 and NANOG in inner cell mass explants from in vitro produced blastocysts over 14 days.