University of Louisville

Poster Title

Sequence Analyses of a Large Multigene Family of 7 kDa Pheromones from Plethodon shermani

Institution

University of Louisville

Abstract

Plethodon shermani salamanders, indigenous to the mountains of western North Carolina, have been of great interest to evolutionary scientists due to their unique courtship behavior. The mating ritual involves the male turning back and slapping his mental gland to the female's nares whilst having his tail straddled. The function of the slap is the delivery of nonvolatile, proteinaceous pheromones designed to increase the female's receptivity. In behavioral tests, the 7-kDa family of pheromones known as Plethodontid Modulating Factor (PMF) decreases receptivity, yet increases it when part of the whole extract. An oddity of these PMFs is their highly conserved untranslated region (UTR) within the mRNA. RT-PCR first produced a cDNA library followed by a novel PCR amplification with primers designed to anneal to the UTR of only PMFs; those sequences were selectively amplified, cloned, and sequenced, yielding 48 PMF isoforms. Shotgun sequencing of previous library constructs yielded 32 unique PMF isoforms, resulting in a total of 80 isoforms. These sequences show both commonality and distinctions in the coding region, and based upon the signal peptide were separated into three major subfamilies. Despite significant homology to xenoxins and snake cytotoxins - particularly in their quadruple disulfide bonding motif - the majority of PMFs constitute two of the subfamilies, and in contrast to other three-finger proteins, carry a negative charge. Having a direct influence on female receptivity and exhibiting such large variability, these pheromones are likely to serve as a powerful model of not only gene regulation but also evolution and speciation.

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Sequence Analyses of a Large Multigene Family of 7 kDa Pheromones from Plethodon shermani

Plethodon shermani salamanders, indigenous to the mountains of western North Carolina, have been of great interest to evolutionary scientists due to their unique courtship behavior. The mating ritual involves the male turning back and slapping his mental gland to the female's nares whilst having his tail straddled. The function of the slap is the delivery of nonvolatile, proteinaceous pheromones designed to increase the female's receptivity. In behavioral tests, the 7-kDa family of pheromones known as Plethodontid Modulating Factor (PMF) decreases receptivity, yet increases it when part of the whole extract. An oddity of these PMFs is their highly conserved untranslated region (UTR) within the mRNA. RT-PCR first produced a cDNA library followed by a novel PCR amplification with primers designed to anneal to the UTR of only PMFs; those sequences were selectively amplified, cloned, and sequenced, yielding 48 PMF isoforms. Shotgun sequencing of previous library constructs yielded 32 unique PMF isoforms, resulting in a total of 80 isoforms. These sequences show both commonality and distinctions in the coding region, and based upon the signal peptide were separated into three major subfamilies. Despite significant homology to xenoxins and snake cytotoxins - particularly in their quadruple disulfide bonding motif - the majority of PMFs constitute two of the subfamilies, and in contrast to other three-finger proteins, carry a negative charge. Having a direct influence on female receptivity and exhibiting such large variability, these pheromones are likely to serve as a powerful model of not only gene regulation but also evolution and speciation.