creating the hair. FGFs, BMPs, and Shh are secreted proteins whose binding to receptors on susceptible cells triggers signal transduction changes and transcription Hairs in mammals and feathers in birds are two of the of target genes. Notch receptor, in contrast, is activated smallest and most fascinating organs in the body. These by membrane-bound ligands such as Delta-1 on the keratinized ski...

OBJECTIVE To determine and optimize the sensitivity of the CellaVision DM96 automated image-analysis system in detecting platelet (PLT) clumps on blood smears and to assess the reliability of the traditional laboratory practice of examining only the feather edge of the smear for PLT clumps. METHODS We processed 102 blood smears that revealed PLT clumps on microscopic review, using the CellaVi...

A study was conducted to determine pigeons from the urban to performed by atomic absorption spectrophotometry with air acetylene (G.B.C. Advanta) Lead concentration was significantly higher in urban sites compared to rural site. Primary feather of pigeon and tail feather of urban sites had significantly higher lead concentration than their rural counterpart. The result of the present study show...

Progress on the evolutionary origin and diversification of feathers has been hampered by conceptual problems and by the lack of plesiomorphic feather fossils. Recently, both of these limitations have been overcome by the proposal of the developmental theory of the origin of feathers, and the discovery of primitive feather fossils on nonavian theropod dinosaurs. The conceptual problems of previo...

ABSTRACT.-Parasites may affect host behavior in a number of ways, including their locomotory performance. We investigated whether the number of holes produced by the feather louse (Myrsidea rustica) affected flight behavior in adult male Barn Swallows (Hirundo rustica) by video-taping flight performance of individuals during escape and level flight. Percentage of time spent flapping during fora...

Six feather mites of the Violet-capped Woodnymph, Thalurania glaucopis are herein reported: Allodectes sejugaspis sp. n., A. thaluraniae sp. n., Trochilodectes brevipenis sp. n., Toxerodectes biscutatus Park & Atyeo (Proctophyllodidae), and two unidentified species from the families Analgidae (Protalginae, genus Protalges) and Ptyssalgidae (genus Ptyssalges). These are the first feather mites t...

1. Possible association between high rates of feather pecking and increased stress were investigated in laying hens. 2. From week 19 to week 30 after hatching, 16 groups of 11 hens (white Lohman Selected Leghorn hybrids) were kept in pens with or without long-cut straw as foraging material and provided with food in the form of pellets or mash. 3. Stress was assessed by egg production, weight ga...

Raptors that consume game species may ingest lead fragments or shot embedded in their prey’s flesh. Threatened Spanish imperial eagles Aquila adalberti feed on greylag geese in southern Spain in winter, and often ingest lead shot. We analysed bone and feather samples from 65 Spanish imperial eagle museum specimens collected between 1980 and 1999, to investigate the prevalence of elevated lead c...

Evolution of adaptation requires both generation of novel phenotypic variation and retention of a locally beneficial subset of this variation. Such retention can be facilitated by genetic assimilation, the accumulation of genetic and molecular mechanisms that stabilize induced phenotypes and assume progressively greater control over their reliable production. A particularly strong inference int...

How organs are shaped to specific forms is a fundamental issue in developmental biology. To address this question, we used the repetitive, periodic pattern of feather morphogenesis on chicken skin as a model. Avian feathers within a single tract extend from dome-shaped primordia to thin conical structures with a common axis of orientation. From a systems biology perspective, the process is prec...