Biomedical subjects

Paul A Wheeler

Publications and source records attributed to Paul A Wheeler.

3 recordsLinked to original sources

PubMed2006

Quantitative trait loci x maternal cytoplasmic environment interaction for development rate in Oncorhynchus mykiss.

Effects of maternal cytoplasmic environment (MCE) on development rate in rainbow trout were evaluated within a quantitative trait loci (QTL) analysis framework. Previous research had identified QTL for development rate in doubled haploid (DH) progeny produced from a cross between the Oregon State University (OSU) and the Swanson (SW) River rainbow trout clonal lines. In this study, progeny for QTL mapping were produced from a cross between the OSU and Clearwater (CW) River clonal lines. Doubled haploids were produced from the OSU x CW F1 by androgenesis using eggs from different females (or MCEs); with androgenesis, the maternal nuclear genome was destroyed by irradiation and diploidy was restored by blocking the first embryonic cleavage by heat shock. All embryos were incubated at the same temperature and development rate quantified as time to hatch. Using a linkage map constructed primarily with AFLP markers, QTL mapping was performed, including MCE covariates and QTL x MCE effects in models for testing. The major QTL for development rate in the OSU x SW cross overlaps with the major QTL found in this OSU x CW cross; effects at this locus were the same across MCEs. Both MCE and QTL x MCE effects contribute to variability in development rate, but QTL x MCE were minor and detected only at small-effect QTL.

Animals↗

PubMed2004

Behavioral differences among rainbow trout clonal lines.

Salmonid fish show considerable geographical variation in morphology, physiology, and behavior. Understanding the genetic mechanisms underlying this variation could be useful for enhancing aquaculture stocks, identifying unique populations for conservation, and determining the genetic factors underlying natural adaptation and domestication. As a first step toward the genetic dissection of salmonid behavioral diversity, we examined variation in behavior patterns among four clonal lines of rainbow trout ( Oncorhynchus mykiss ) derived from geographically diverse source populations with different domestication histories. Clonal lines were crossed with two outbred (i.e., not homozygous) females, and the resulting progenies were reared and tested under identical conditions. Clonal line had significant genetic effects on mean swim level, hiding, foraging, startle response, and aggression level. Multiple comparisons suggest that domestication history of the source populations had a strong influence on these behavior patterns. Progeny of two clonal lines derived from populations reared in captivity for over 100 years exhibited reductions in predator avoidance behavior patterns and increases in aggression compared to progeny of two clonal lines from more recently domesticated populations. These results will facilitate future investigation of the genetic factors underlying population variation in these behavior patterns influenced by domestication.

Animals↗

PubMed2004

Polymorphism and differentiation of rainbow trout Y chromosomes.

Most fish species show little morphological differentiation in the sex chromosomes. We have coupled molecular and cytogenetic analyses to characterize the male-determining region of the rainbow trout (Oncorhynchus mykiss) Y chromosome. Four genetically diverse male clonal lines of this species were used for genetic and physical mapping of regions in the vicinity of the sex locus. Five markers were genetically mapped to the Y chromosome in these male lines, indicating that the sex locus was located on the same linkage group in each of the lines. We also confirmed the presence of a Y chromosome morphological polymorphism among these lines, with the Y chromosomes from two of the lines having the more common heteromorphic Y chromosome and two of the lines having Y chromosomes morphologically similar to the X chromosome. The fluorescence in situ hybridization (FISH) pattern of two probes linked to sex suggested that the sex locus is physically located on the long arm of the Y chromosome. Fishes appear to be an excellent group of organisms for studying sex chromosome evolution and differentiation in vertebrates because they show considerable variability in the mechanisms and (or) patterns involved in sex determination.

Animals↗