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Pigmentation Patterns (pigmentation + pattern)
Selected AbstractsCharacterization of a dorsal-eye Gal4 Line in DrosophilaGENESIS: THE JOURNAL OF GENETICS AND DEVELOPMENT, Issue 1 2010Clayton M. Morrison A transgenic fly that expresses Gal4 specifically in the dorsal (upper) half of the eye. This transgene also expresses the white gene as a marker. This white gene construct is normally expressed in all eye cells, however, in this transgenic fly its expression is silenced in the ventral (lower) half of the eye resulting in the observed adult eye pigmentation pattern. The dorsal eye expression of Gal4 is a useful tool to overexpress UAS-driven transgenes specifically in half the eye. See the paper by Morrison and Halder in this issue. [source] NATURAL SELECTION ALONG AN ENVIRONMENTAL GRADIENT: A CLASSIC CLINE IN MOUSE PIGMENTATIONEVOLUTION, Issue 7 2008Lynne M. Mullen We revisited a classic study of morphological variation in the oldfield mouse (Peromyscus polionotus) to estimate the strength of selection acting on pigmentation patterns and to identify the underlying genes. We measured 215 specimens collected by Francis Sumner in the 1920s from eight populations across a 155-km, environmentally variable transect from the white sands of Florida's Gulf coast to the dark, loamy soil of southeastern Alabama. Like Sumner, we found significant variation among populations: mice inhabiting coastal sand dunes had larger feet, longer tails, and lighter pigmentation than inland populations. Most striking, all seven pigmentation traits examined showed a sharp decrease in reflectance about 55 km from the coast, with most of the phenotypic change occurring over less than 10 km. The largest change in soil reflectance occurred just south of this break in pigmentation. Geographic analysis of microsatellite markers shows little interpopulation differentiation, so the abrupt change in pigmentation is not associated with recent secondary contact or reduced gene flow between adjacent populations. Using these genetic data, we estimated that the strength of selection needed to maintain the observed distribution of pigment traits ranged from 0.0004 to 21%, depending on the trait and model used. We also examined changes in allele frequency of SNPs in two pigmentation genes, Mc1r and Agouti, and show that mutations in the cis -regulatory region of Agouti may contribute to this cline in pigmentation. The concordance between environmental variation and pigmentation in the face of high levels of interpopulation gene flow strongly implies that natural selection is maintaining a steep cline in pigmentation and the genes underlying it. [source] First description of larvae of Acanthodraco dewitti in the Ross Sea, AntarcticaJOURNAL OF FISH BIOLOGY, Issue 2000M. La Mesa Six postlarval and an adult bathydraconid were collected in Terra Nova Bay, Ross Sea, during January-February 1988 and February 1998, respectively. The adult was identified as Acanthodraco dewitti Skóra, 1995 (type locality South Shetland Islands), a species not recorded in the Ross Sea. The postlarvae may be those of A. dewitti. The morphology and pigmentation patterns of the postlarvae are described and compared with those of other bathydraconids. [source] Prevalence of Unilateral and Bilateral Deafness in Border Collies and Association with PhenotypeJOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 6 2006Simon Platt Background:Congenital sensorineural deafness (CSD) occurs in Border Collies, but its prevalence and inheritance are unknown. This study estimated the prevalence of CSD in Border Collies and investigated its association with phenotypic attributes linked to the merle gene, including coat pigmentation and iris color. Hypothesis:Deafness in Border Collies is associated with pigmentation patterns linked to the merle gene. Animals:A total of 2597 Border Collies from the United Kingdom. Methods:A retrospective study of Border Collies tested, during 1994,2002, by using brainstem auditory evoked responses. Associations between deafness and phenotypic attributes were assessed by using generalized logistic regression. Results:The prevalence of CSD in puppies was estimated as 2.8%. The corresponding rates of unilateral and bilateral CSD were 2.3 and 0.5%, respectively. Adjustment for clustering of hearing status by litter reduced the overall prevalence estimate to 1.6%. There was no association between CSD and sex (P= .2). Deaf Border Collies had higher rates of merle coat pigmentation, blue iris pigment, and excess white on the head than normal hearing Border Collies (all P < .001). The odds of deafness were increased by a factor of 14 for Border Collies with deaf dams, relative to the odds for dogs with normal dams (P= .007), after adjustment for phenotypic attributes. Conclusions and Clinical Importance: Associations between CSD and pigmentation patterns linked to the merle gene were demonstrated for Border Collies. Evidence for an inherited component to CSD in Border Collies supports selective breeding from only tested and normal parents to reduce the prevalence of this disease. [source] | ||||||||||