Effect of solvent residues of Vitex negundo L. and Cassia fistula L. leaves (0.5 and 1%) was studied on egg laying and adult emergence of Callosobruchus maculatus Fab. and on percentage of larval parasitism by Dinarmus vagabundus (Timberlake). Cowpea seeds treated with methanol and aqueous extract of Vitex, at these concentrations (0.5 and 1%), significantly reduced the number of eggs and emerg...

The mechanisms by which cancer evolves and persists in natural systems have been difficult to ascertain. In the Xiphophorus melanoma model, a functional oncogene (Xiphophorus melanoma receptor kinase Xmrk) has been maintained for several million years despite being deleterious and in an extremely unstable genomic region. Melanomas in Xiphophorus spp. fishes (platyfishes and swordtails) have bee...

The genetic basis of spontaneous melanoma formation in spotted dorsal (Sd) Xiphophorus platyfish-swordtail hybrids has been studied for decades, and is adequately explained by a two-gene inheritance model involving a sex-linked oncogene, Xmrk, and an autosomal tumor suppressor, DIFF. The Xmrk oncogene encodes a receptor tyrosine kinase related to EGFR; the nature of the DIFF tumor suppressor ge...

A review of some exciting new directions for Xiphophorus research in behavioral ecology and integrative animal behavior is presented. The primary objective of this review is to identify areas of research in this teleost genus that, if studied further, could yield insights into the manifold causes and consequences of dominance encounters that will have broad relevance in the behavioral biology c...

Hysteresis in material behaviour includes both signum nonlinearities as well as high dimensionality. Available models for component-level hysteretic behaviour are empirical. Here, we derive a low-order model for rate-independent hysteresis from a high-dimensional massless frictional system. The original system, being given in terms of signs of velocities, is first solved incrementally using a l...

When a black-spotted female platyfish (Platypoecilus maculatus) is mated to an unspotted (genetically recessive) male platyfish, one of three hereditary expressions may be expected. If the female is genetically pure (homozygous dominant) for the spotted factor, all of the young may be expected to be spotted. The genetic formula representing this situation is (W)Sp(Z)Sp, for the mother, where W ...

The overexpression of the Xmrk oncogene (ONC-Xmrk) in pigment cells of certain Xiphophorus hybrids has been found to be the primary change that results in the formation of malignant melanoma. Spontaneous mutant stocks have been isolated that have lost the ability to induce tumor formation when crossed with Xiphophorus helleri. Two of these loss-of-function mutants were analyzed for genetic defe...

Analysis of genotypes of 76 polymorphic loci in more than 2600 backcross hybrid individuals derived from intra- and interspecific genetic crosses of fishes of the genus Xiphophorus (Poeciliidae) resulted in the identification of 17 multipoint linkage groups containing 55 protein-coding loci and one sex chromosome-linked pigment pattern gene. Multipoint linkage analyses identified highly probabl...

INTRODUCTION In 65 genotypes of Xiphophorus (nonhybnids and inter populational and interspecific F and backcnoss hybrids), the susceptibility to neuroblastoma following treatment with carcinogenic-mutagenic agents was tested. The fish were exposed to an aqueous solution of N-methyl-N-n itro sounea (MNU) or exposed to X-rays. Neunoblastoma was induced by MNU in 64 of about 3500 treated fish and ...

A century of research into both behavior and genetics in Xiphophorus has yielded important insights into the genetic architecture underlying sexual behavior, particularly as concerns male courtship and mating strategies. Two Y-linked loci underlie much of the variation in male mating strategies, possibly reflecting selection for modularization. Courtship behavior elements, in contrast, are unde...