Research Interests
Role of Growth Hormone Locus in Fetal Growth; Molecular Evolution and Systematics
The human growth hormone locus contains five closely-related genes - two for growth hormone genes and three for chorionic somatomammotropin (placental lactogen). All of these genes are tandemly arranged on the same chromosome over a span of about 46,000 nucleotides. Four of these genes are expressed only in the placenta and their encoded proteins play a significant role in stimulating fetal growth and facilitating nutrient availability to the fetus. Additionally, the locus is undergoing a myriad of unique genetic processes, including gene conversion, unequal recombination, functional divergence, and accelerated change. My laboratory is working on the role of these genes in fetal growth retardation in humans using biochemical and genetic epidemiological approaches. In particular, we are identifying single nucleotide polymorphisms (SNPs) and major lesion in the growth hormone locus and determining their association with fetal size at term. We are also studying the origin of this unique locus, the underlying basis for the functional divergence of the proteins, and the rate of spontaneous mutation in humans.
The other area of emphasis in my laboratory is the use of molecular
data to decipher past events. For example, the major lineages of
placental mammals arose rapidly near the end of the Cretaceous,
making it difficult to reconstruct their evolutionary relationships.
I am using nucleotide sequence data generated in the automated
sequencing facility I manage to determine relationships among
the main groups of mammals (esp. rodents) and to estimate the dates
of these speciation events. These studies involve sequencing biomedically
important genes, for example those associated with cancer, in a
variety of mammals ranging from humans to endangered species distributed
throughout the world. I also am engaged in theoretical studies to
determine the best mathematical models to describe observed patterns
of nucleotide differences among sequences and how these models can
best be applied to reconstructing evolution. Ideally, these models
should incorporate such parameters as changes in nucleotide or amino
acid composition among species and variable rates of change among
different species and among different portions of the molecule.
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Representative Publications
Adkins, R. M., Nekrutenko, A. and Li, W.-H. (In press.) Bushbaby growth hormone is much more similar to nonprimate growth hormones than to rhesus monkey and human growth hormones. Molecular Biology and Evolution.
Madsen, O., Scally, M., Douady, C. J., Kao, D. J., DeBry, R. W., Adkins, R., Amrine, H. M., Stanhope, M. J., de Jong, W. W., and Springer, M. S. (Accepted) Molecules untangle the basal divergences of the placental mammals. Nature.
Liu, J.-C., Makova, K. D., Adkins, R. M., Gibson, S., and Li, W.-H. (In review.) Molecular coevolution of growth hormone and its receptor in primates. Mol. Biol. Evol.
Adkins, R. M. (In review.) Molecular coevolution. In Encyclopedia of the human genome. Macmillan Publishers Ltd, London.
Adkins, R. M., Vanedeberg, J., and Li, W.-H. 2000. Molecular evolution of growth hormone and receptor in the guinea pig, a mammal unresponsive to growth hormone. Gene. 246: 357-363.
Honeycutt, R. L., and Adkins, R. M. 1993. Higher level systematics of eutherian mammals: an assessment of molecular characters and phylogenetic hypotheses. Ann. Rev. Ecol. Syst. 24: 279-305.
Adkins, R.M. and R.L. Honeycutt. 1991. A molecular phylogeny of the superorder Archonta. Proc. Nat. Acad. Sci. USA 88: 10317-10321.
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