BACKGROUND The Drosophila segment polarity gene hedgehog encodes a member of a family of secreted proteins that are involved in a variety of patterning processes, in both vertebrates and invertebrates. Some of these processes depend upon short-range or contact-dependent interactions, whereas others seem to involve long-range signalling. Two different models have been proposed to account for the...

Red-eared slider turtles are genetically bipotential for sex determination, with incubation temperature of the egg determining gonadal sex. At higher incubation temperatures, females are produced, possibly due to increased biosynthesis of estrogen. Exogenous estrogen causes the formation of ovaries, and prevention of estrogen biosynthesis results in the development of testes. In mammals, steroi...

A distributional isolate in southwestern Western Australia previously assigned to Gould’s Long-eared Bat Nyctophilus gouldi Tomes, 1858 is demonstrated be a distinct and unnamed cryptic species, based on lack of monophyly with eastern populations substantial DNA sequence divergence (5.0 %) at the mitochondrial gene COI. Morphologically both species are alike overlap all measured characters but ...

Fine-tuned Notch and Hedgehog signalling pathways via attenuators and dampers have long been recognized as important mechanisms to ensure the proper size and differentiation of many organs and tissues. This notion is further supported by identification of mutations in these pathways in human cancer cells. However, although it is common that the Notch and Hedgehog pathways influence growth and p...

The Hedgehog morphogen is a major developmental regulator that acts at short and long range to direct cell fate decisions in invertebrate and vertebrate tissues. Hedgehog is the only known metazoan protein to possess a covalently linked cholesterol moiety. Although the role of the cholesterol group of Hedgehog remains unclear, it has been suggested to be dispensable for the its long-range activ...