Anthraquinones in Digitalis species

Twenty anthraquinones have been found in the roots of Digitalis trojana of which the following are new: digitopurpone-1-methyl ether, ω-hydroxypacybasin and ω-hydroxyziganein. The biogenesis of the thirty anthraquinones now known in Digitalis s.l. is discussed.     

Effects of benfluorex-vitamin C supplementation on cutaneous capillaries of diabetic rats

The ultrastructural changes on capillaries of the dermis in diabetic and benfluorex-vitamin C treated diabetic rats have been investigated. Three groups of 21 Wistar albino rats were used in the examination: control, diabetes, and benfluorex-vitamin C treated diabetic rats. Diabetes was induced by injection of streptozotocin. The streptozotocin-induced group was treated for 21 days with vitamin C and benfluorex, of which antidiabetic and antihyperlipidemic effects were experimentally proved. Samples taken from the skin of rats' legs were examined under transmission electron microscopy. Swollen endothelial cells, narrowed capillary lumens, a thickened basement membrane, and fusion of mitochondrial cristae in the capillaries of diabetic rat dermis were seen. In the benfluorex-vitamin C treated group, contrary to the diabetic group, neither signs of degeneration in endothelial cells nor a significant difference with the control group with regard to capillary structure were observed. Amelioration in capillaries appears to be due to benfluorex and vitamin C treatment in diabetes.     

Appearance of LH-immunoreactive cells in the Rathke's pouch of the chicken embryo

The differentiation of the pituitary of the chicken embryo was studied by means of an immunohistochemical technique using antisera to turkey and chicken pituitary hormones. Immunoreactive LH-cells are detected in 4-day embryos (stage 23 of Hamburger and Hamilton) when the primordium of the anterior pituitary, the Rathke's pouch is only composed of a single-layer epithelium lined with an undifferentiated mesenchyme. A few immunoreactive cells are observed grouped on the posterior aspect of the pouch. As development proceeds, a strip of positive cells is detected encircling the Rathke's pouch. Prolactin-, growth hormone-, and ACTH-immunoreactive cells are detected in 6- and 7-day embryos, only after the pituitary has acquired its characteristic structure with cords in which different cell types become progressively recognizable. The early appearance of immunoreactive LH-cells following a precise distribution shows that secretory properties and differentiation capacities are acquired simultaneously in the epithelium of the Rathke's pouch and may be induced by the same stimulus.     

Thyrotropes in the pituitary are target cells for 1,25 dihydroxy vitamin D3

Summary In the anterior pituitary of the rat, target cells of 1,25 (OH)₂ vitamin D₃ are identified as those that secrete thyroid stimulating hormone by means of a combined technique of thaw-mount autoradiography and immunohistochemistry. The results for the first time provide evidence that suggests a central effect of 1,25 (OH)₂ vitamin D₃ on the modulation of thyrotropin secretion in a manner similar to that of other steroid hormones at the level of the pituitary.Supported by PHS grant NS09914     

Different trends of neighboring populations of Lesser Kestrel: Effects of climate and other environmental conditions

The sensitivity of population trends to the climate and environment is generally considered a species-specific trait. However, evidence that populations may show different responses to the climate and environmental conditions is growing. Whether this differential sensitivity may arise even among neighboring populations remains elusive. We compared the trends of two neighboring populations of the Lesser Kestrel Falco naumanni, using data from a 12-year survey of 158 colonies in Sicily, Italy; the two populations inhabiting a lowland and an highland area, respectively. Population trends were modeled through the TRIM algorithms implemented in R (package rtrim). A reversed U-shaped population trend was observed in the lowland, while the highland population showed oscillations around a stable trend. Sahel rainfall 2 years before each annual survey significantly affected population variation in the lowland, while rainfall in March and an index of primary productivity in the breeding areas affected population variation in the highland. This suggests that the population in the lowland may be limited mainly by winter survival in Sahel, because the lowland may be an optimal breeding area for this species. In contrast, the highland population, which occupies a different part of the climatic niche of the species, may be limited mainly by reproductive output, because rainfall in March and the primary productivity in May could represent prey availability immediately before and during the breeding months. Overall, our findings suggest that population-specific environmental sensitivity might occur even over small (<100 km) geographical scales, highlighting the need for population-specific conservation strategies.     

Drag reduction of fish skin mucus: Relationship to mode of swimming and size

Drag reduction by skin mucus was measured from Gulf of Eilat fish. Activity of burst swimmers was greater than manoeuvre swimming fish. Large fish from the same species had higher mucus drag reducing activity than smaller specimens.