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3258 TAMU Office: Lab: Fax: 979-845-2891 |
Biography |
| Ira Greenbaum received a B.A. (1973) in Biology from Hofstra University and an M.S. (1975) in Biology and Ph.D. (1978) in Zoology from Texas Tech University. He joined the Department of Biology at Texas A&M Univerity in 1978. He was promoted to Associate Professor in 1984 and then promoted to Professor in 1988. He is currently a member of the Faculty of Genetics, Center for Animal Biotechnology and Center for Animal Genetics. He is also the Director for Lower Division Instruction. | |
| Vertebrate Cytogenetics | |
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The research in this laboratory is focused around questions concerning chromosomal rearrangement and it role(s) in vertebrate evolution. Although this usually involves assessments of intraspecific (populational) chromosomal polymorphism, the data are generally applicable to systematic interpretations and considerable attention is paid to the phylogenetic relationships and higher taxonomic patterns of chromosomal evolution. The systematic relationships of the species studied are typically used to establish the experimental design of the hypotheses tested. Our assessments of karyotypic rearrangement and chromosomal homology involve analyses of non-differentially stained and specifically- banded metaphase chromosomes. Although deer mice (Peromyscus) are our primary model, recent projects have also addressed cytogenetic questions in birds and reptiles. The laboratory contains complete facilities for light microscopy and imaging, tissue culturing and allozymic analyses. Recent emphasis has addressed questions concerning the meiotic effects of chromosomal mutations that are maintained as populational polymorphisms and that constitute the modes of karyotypic evolution in the organisms under study. This research has involved electron microscopic studies of the synaptonemal complex and corresponding analyses of meiotic chromosomes. Our publications in this area have documented unexpected levels of variability in meiotic pairing, meiotic mechanisms which foster the incorporation specific chromosomal mutations, unequal recombination of sex heterochromatin and a revised view of the causes and effects of chromosomal evolution. Our current emphases concern the genetics and evolutionary relevance of chromosomal fragile sites and continued studies of the systematics and evolution of the Peromyscus maniculatus species group. This former experimental design involves mapping fragile sites within and among deer mouse populations and species. These studies are designed to document the genetic variability and evolutionary rate of chromosomal fragile sites and to determine whether these sites constitute loci which preferentially undergo chromosomal evolution. The latter reflects our continued interest in the evolution of deer mice and the use of these as model species for examining character state evolution. |
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| Selected Publications | |
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Walker. M.L., S.E. Chirhart, A.F. Moore, R.L. Honeycutt and I.F. Greenbaum. 2006. Genealogical concordance and the specific status of Peromyscus sejugis. J of Hered 97(4):340-345. Chirhart , S.E., R. L. Honeycutt, and I. F. Greenbaum. 2005. Microsatellite variation and evolution in the Peromyscus maniculatus species group. Molec Phylo Evo 34:408-415 Denison, S.R., R.K. Simper and I.F. Greenbaum. 2003. How common are common fragile sites in humans: interindividual variation in the distribution of aphidicolin-induced fragile sites. Cytogen Genome Res 101:8-16. Denison, S.R., A. S. Multani, S. Pathak and I.F.Greenbaum. 2002. Fragility in the 14q21q translocation region. Genetics and Molecular Biology, 25:217-276. Dahm, P.F., A.W. Olmsted and I.F. Greenbaum. 2002. Probability models and the applicability of statistical procedures in the identification of chromosomal fragile sites. Biometrics 58:139-142. Berend, S.A., D.W. Hale, M.D. Engstrom and I.F. Greenbaum. 2001. Cytogenetics of collared lemmings (Dicrostonyx groenlandicus). II. Meiotic behavior of B chromosomes suggests a Y-chromosomal origin of supernumerary chromosomes. Cytogenet Cell Genet 95:85-91. Chirhart, S.E., R. Arianpour, R.L. Honeycutt and I.F. Greenbaum. 2001. Mitochondrial-DNA sequence variation and the specific identification of deer mice (Peromyscus) from Triangle Island, British Columbia, Canada. Can J Zool 79:2257-2260. Smith, L.R., D.W. Hale, and I.F. Greenbaum. 2000. Systematic implications of chromosomal data from two insular species of Peromyscus from the Gulf of California. J. of Hered. 91: 162-165. McClure, M.R. and I.F. Greenbaum. 1999. Electrophoretic variation and biogeography of snapping shrimp (Alpheus) from the Gulf of Mexico and northwestern Atlantic coasts. Southwestern Nat. 44: 462-469. Dawson, W.D., S.R. Young, Z.W. Wang, L.W. Liu, I.F. Greenbaum, L.m. Davis, and B.K. Hall. 1999. Mus and Peromyscus chromosome homology established by FISH with three mouse paint probes. Mammalian Genome 10: 730-733. Berend, S.A., D.W. Hale, M.D. Engstrom, and I.F. Greenbaum. 1997. Meiotic analyses of the neo-XY sex chromosomes in the collard lemming (Dicrostonyx groenlandicus). Cytogenet. Cell Genet. 79: 288-292. Greenbaum, I.F., D.K. Walpole, and S.K. Davis. 1997. Mitochondrial DNA variation in populations of Peromyscus eremicus from the Chichuahua and Sonora deserts. J. Mamm. 78: 397-404. Greenbaum, I.F. and B.F. McAllister. 1997. How common are common fragile sites: variation of aphidicolin-induced chromosomal fragile sites in a population of the deer mouse (Peromyscus manuculatus). Hum. Genet. 100: 182-188. |
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