Progress 10/01/98 to 09/30/03
Outputs
Progress Report Research was completed which established the developmental profile of MHC protein expression in the early differentiation stages (pre-blastula, blastula, gastrula and neurula) and older growth stages of embryogenesis. Studies were conducted using an industry stock of egg-type chickens. Embryos prior to incubation and to 15 days of incubation were studied. The three main classes of MHC proteins were studied, Class I (BF), Class II (BL) and Class IV (BG). MHC proteins were found expressed on cells from early stage embryos as well as on somatic cells from older embryos. Research was initiated to examine expression of telomerase genes during embryo development to correlate gene expression with telomerase activity and chromosome stability, in the immune system during development. The University of California-Davis collection of specialized poultry genetic populations (developmental mutants, cytogenetic variants and immunogenetic lines) which are essential for
studies in developmental biology, genetics/genomics and immune function, were bred and maintained. Genetic lines were made available to researchers on request.
Impacts
MHC-encoded communication molecules may impact the success of cellular manipulation using early embryos and primordial germ cells. Thus, this research develops knowledge significant to biotechnology applications for the chicken. It is essential that the research populations developed during the previous 50 year are maintained as these are essential for understanding avian and poultry biology.
Publications
- Delany, M.E. 2003. Genetic diversity and conservation of poultry. Chapter 15, p 257-281.In Poultry Genetics, Breeding and Biotechnology (editors: W.E. Muir and S.E. Aggrey). CABI Publishing, Wallingford, UK.
- Fulton, J.E., and M.E. Delany, 2003. Poultry genetic resources: Operation rescue needed. Science 300:1667-1668.
- Spanakos, M.V. 2003. Expression of the Major Histocompatibility Complex (MHC) during Early Chicken Embryogenesis. M.S. Thesis University of California, Davis CA 95616
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Progress 01/01/02 to 12/31/02
Outputs
Research continued to establish the developmental profile of MHC gene expression in early stage embryos. Stages of development under study included embryos from 0 hour of incubation (pre-blastula stage) to 15 days of incubation. Expression of three loci included Class I (B-F), Class II (B-L) and Class IV (B-G) proteins. Organs or cell layers were studied. At several stages for several of the loci, unexpectedly high percentages of cells expressing the antigens were observed. The results are being verified by repeating the experiments. -The University of California-Davis collection of specialized poultry genetic populations, which are useful for studies in developmental biology, genetics/genomics and immune function, were maintained and made available to researchers on request.
Impacts
Research with model organisms and in humans, indicates that MHC proteins may have important non-immune signaling functions during early embryogenesis. Our research will establish the potential of a new role for the MHC, during early embryogenesis in chicken. Cell recognition may affect impact cellular interactions prior to and during morphogenesis and thus the success of several biotechnology efforts (culture of embryonic blastodermal cells and creation of germline chimeras from blastodermal cells) may hinge on MHC-controlled recognition. -- As agricultural research at many institutions has changed, it is important that the specialized genetic populations developed during the previous 50 year are maintained for research. The specialized genetic lines are not likely to be re-created in the future and these hold important promise for the future understanding of avian and poultry biology. Many of these lines are not available except from UC-Davis and are made available
to other researchers on request.
Publications
- No publications reported this period
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Progress 01/01/01 to 12/31/01
Outputs
New collaborative research was undertaken to establish the developmental profile of expression of major histocompatibility complex (MHC) genes during embryonic development, prior to organogenesis. The main hypothesis under study is that MHC-encoded proteins serve as cell-recognition elements guiding early embryonic morphogenesis and differentiation. The status of the research is too early to provide definitive results statements. - The University of California-Davis collection of specialized poultry genetic populations, which are useful for studies in developmental biology, genetics/genomics and immune function, were maintained and made available to researchers on request.
Impacts
Research with model organisms and in humans, indicates that MHC proteins may have important non-immune signaling functions during early embryogenesis. Our research will establish the potential of a new role for the MHC, during early embryogenesis in chicken. Cell recognition may affect impact cellular interactions prior to and during morphogenesis and thus the success of several biotechnology efforts (culture of embryonic blastodermal cells and creation of germline chimeras from blastodermal cells) may hinge on MHC-controlled recognition. -- As agricultural research at many institutions has changed, often down-sized due to faculty retirements and the advent of significant growth of molecular biology research, it is important that the specialized genetic populations developed during the previous 50 year are maintained for research. The specialized genetic lines are not likely to be re-created in the future and these hold important promise for the future understanding
of avian and poultry biology. Many of these lines are not available except from UC-Davis and are made available to other researchers on request.
Publications
- Pisenti, J.M., M.E. Delany, R.L. Taylor, Jr., U.K. Abbott, H. Abplanalp, J.A. Arthur, M.R. Bakst, C. Baxter-Jones, J.J. Bitgood, F. Bradley, K.M. Cheng, R.R. Dietert, J.B. Dodgson, A. Donoghue, A.E. Emsley, R. Etches, R.R. Frahm, R.J. Gerrits, P.F. Goetinck, A.A. Grunder, D.E. Harry, S.J. Lamont, G.R. Martin, P.E. McGuire, G.P. Moberg, L.J. Pierro, C.O. Qualset, M. Qureshi, F. Schultz, and B.W. Wilson. 2001. Avian Genetic Resources at Risk: An assessment and proposal for conservation of genetic stocks in the USA and Canada. Avian and Poultry Biology Reviews. 12 (1&2):1-102.
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Progress 01/01/00 to 12/31/00
Outputs
Research was completed on the topic of genetic variation within and among commercial broiler and layers lines. The locus studied was the ribosomal DNA complex encoding the 18S,5.8S,28S ribosomal RNA genes. This locus is of critical importance for ribosome production and it is linked to the major histocompatibility complex (MHC). The data indicated that commercial broiler populations show greater levels of diversity than egg-production stocks; the latter showing a high degree of similarity between individuals within lines and among foundation lines from different primary breeder firms. Difference in diversity may be related to the genetic base of the broiler populations (derived from several breeds) and layers (derived from a single breed) but also selection parameters used for broilers versus layers populations. New collaborative research is underway to establish the developmental profile for expression of major histocompatibility complex genes during embryonic
development, which may affect cellular interactions prior to and during morphogenesis, impacting the success of several biotechnology efforts (culture of embryonic blastodermal cells, creation of germline chimeras from blastodermal cells).
Impacts
Several studies have now shown that commercial egg production (layer) foundation populations have reduced levels of genetic variation. This is cause for concern and consideration should a new or variant major disease emerge affecting commercial populations.
Publications
- Delany, M.E. 2000. Patterns of ribosomal gene variation in elite commercial chicken pure line populations. Animal Genetics 31:110-116.
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Progress 01/01/99 to 12/31/99
Outputs
The ribosomal (r) DNA genotypes within and among the elite commercial pure line foundation populations were studied. The rDNA complex, which maps to microchromosome 16, includes the tandemly repeated 18S, 5.8S, and 28S ribosomal RNA genes. White-egg layer populations exhibited the lowest ribosomal gene copy number average (329 genes) as compared with the brown-egg layer and broiler group averages (372 and 350 genes, respectively). The white-egg layer populations exhibited the largest average repeat unit size (36 Kb) as compared with that of the brown-egg layer and broiler groups (32.5 and 33.9 Kb, respectively). The total rDNA array size was similar among the three groups (6 Mb) due to the inverse relationship between copy number and gene size. Diversity was examined by evaluating the rDNA-types segregating within and among lines of each group. The brown-egg broiler populations exhibited polymorphic patterns whereas the white-egg layer populations were essentially
monomorphic for rDNA-type; brown-egg layers exhibited an intermediate level of diversity. New studies were initiated to begin to dissect the molecular basis for the high recombination rate among the various loci of microchromosome 16. A chicken BAC library is being screened to find a clone containing the junction fragment connecting the ribosomal DNA and the major histocompatibility complex.
Impacts
Studies of genome diversity within and among commercial chicken foundation populations are essential for the poultry industry to establish the genetic heterogeneity remaining in extant commercial stocks of chicken. Adequate genetic heterogeneity is important for continued selection gains.
Publications
- Pisenti, J.M., M.E. Delany, et al. 1999. Avian Genetic Resources at Risk: An assessment and proposal for conservation of genetic stocks in the USA and Canada. Report No. 20, University of California Division of Agriculture and Natural Resources, Genetic Resources Conservation Program, Davis, CA.
- Delany, M.E., and A.B. Krupkin. 1999. Molecular characterization of ribosomal gene variation within and among NORs segregating in specialized populations of chicken. Genome 42:60-71.
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Progress 01/01/98 to 12/31/98
Outputs
Research focused on analysis of recombination within chicken microchromosome(mic) #16. The major histocompatibility complex (MHC), the ribosomal (r) DNA, and the MHC-like Rfp-Y complex were studied in congenic lines of chicken. High rates of recombination between the MHC and the rDNA and Rfp-Y complexes were identified. During the development of the congenic lines, the "donor" mic 16 recombined with the mic 16 of the inbred parent background, exchanging the donor rDNA and Rfp-Y haplotypes for that of the inbred background haplotypes. This was verified by examination of several congenic lines and original inbred parent lines. The results provide evidence supporting the hypothesis that the rDNA is located between MHC and Rfp-Y and that mic 16-encoded loci exhibit higher than expected rates of recombination. High levels of rDNA recombination may serve to alter the inheritance of MHC and Rfp-Y alleles in chicken. This may have positive effects by increasing combinatorial
diversity of alleles in populations that impact disease resistance/susceptibility. Studies were completed on evaluation of rDNA genotypes and nucleogenesis in developing tumors in chicken. Similar to that described for human tumor cells, abnormal nucleolar morphology is associated with metastases. Work continued on conservation and preservation of specialized lines of chicken useful for fundamental and applied research.
Impacts
(N/A)
Publications
- Delany, M.E., and Pisenti, J.M. 1998. Conservation of avian genetic research resources: past, present and future. Poultry & Avian Biol.
- Delany, M.E. 1997. Analysis of v-src initiated primary and metastatic tumors: development of an in vivo model to understand the role of rDNA genotype in progression and regression of tumors. Third Annual Cancer Research Symposium, UC Davis Cancer Center, Sacramento, CA,
- Delany, M.E., Gurel, V., and Taylor, R.L. 1998. Ribosomal DNA genotypes and nucleolar phenotypes of v-src initiated tumors in 6.B congenic chickens. Poultry Sci. 77(sl), p.5 (Abstract).
- Lakshmanan, N., Delany, M.E., and Emara, M.G. 1998. Identification of an MHC class II-like system located outside the classical MHC-bearing chromosome in the chicken. Poultry Sci. 77(sl), p.5 (Abstract).
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Progress 01/01/97 to 12/01/97
Outputs
The 18S, 5.8S and 28S rRNA genes encode the RNAs which form the ribosome, the organelle where mRNAs are translated into proteins. The rDNA has a pivotal role in supporting normal differentiation and growth. Changes in nucleoli (site of rDNA and ribosome biogenesis) are correlated with tumor metastases in humans and aging in yeast. Research focused on characterizing and relating (1) rDNA genotypes, and (2) nucleolar phenotypes during tumorigenesis. The overall goal of the research is to study the molecular and cellular events of oncogenesis in a well-defined genetic system (chicken) as a model for vertebrates and to increase our understanding of tumorigenesis in poultry, of value for the commercial industry. The rDNA genotypes and nucleolar phenotypes of normal tissues, primary tumors and secondary metastases were examined in sarcoma-susceptible birds. No changes in gene copy number or gene family organization were observed, however, nucleolar morphology showed
alterations during tumorigenesis. These results indicate that abnormal nucleolar morphology may be a universal feature associated with oncogenesis in vertebrates and suggests that the abnormal nucleoli do not result from rDNA genotype changes per se (amplification or gene rearrangements). Molecular genotyping of the tumor-susceptible line indicated that 25% of the individuals possess a variant rDNA genotype.
Impacts
(N/A)
Publications
- DELANY, M.E. and PISENTI, J.M. Conservation of poultry genetic research resources: Consideration of the past, present, and future. Poultry and Avian Biol. Rev. (in press).
- DELANY, M.E. 1997. The avian genome: Macro to micro perspectives. Proceedings of the National Breeders Roundtable. Pp 91-108.
- DELANY, M.E. 1997. Molecular characterization of ribosomal RNA gene variation within the single NOR of the chicken. Poultry Sci
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