Immunological relations of proteins from four salmonellae sharing an "O" factor 8.

The proteins from S. virginia, with the sole 8 "O" factor, precipitated against homologous and related heterologous sera by a conspicuous, homogenous line of serological identity, with proteins from: S. newport (6.8), S. blockley (6.8), S. emek (8.20). The proteins, however, were not involved in the bacterial agglutinations since the absorptions, which removed the common precipitins from the sera, did not modify the homologous agglutinations. The results with anti-S. newport and anti-S. blockley sera sharing identical "O" factors while displaying different immunochemical compositions as well as the strong immunochemical relations found between S. virginia and S. newport belonging to the different subgroups C2 and C3 underline the non-relatedness of agglutinins and precipitins.     

Wind as an ecological factor

Wind has long been regarded as an important ecological factor in forests owing to the dramatic damage hurricanes can wreak. However, the long-term wind regime of a site also exerts a strong influence on the growth of trees. A relatively large amount is known about the acclimation of trees to wind but less about intra- or interspecific adaption to high winds. In fact, changes resulting from the effect of wind may have a greater effect on the ecology of forests than the more acute effects of destructive stroms. Improved understanding of the mechanical effects of wind is helping foresters manage their plantations and may help us to account better for local and geographical variations in forest ecology.     

Multiple forms of an angiogenesis factor: basic fibroblast growth factor

An angiogenesis factor has been isolated from human placenta and human hepatoma cells on the basis of its ability to stimulate protease production in cultured capillary endothelial cells. The purified angiogenesis factor also stimulated DNA synthesis and motility in capillary endothelial cells and induced angiogenesis in vivo. Amino acid sequence data revealed that the angiogenesis factor was human basic fibroblast growth factor (bFGF). Other angiogenesis factors isolated on the basis of their ability to stimulate endothelial cell proliferation have also been identified as bFGFs. The bFGFs that have been sequenced show variability in their N-termini. These different forms of bFGF may be naturally occurring processed forms or may be generated by proteases released during the isolation procedure. Recently a bFGF with a large N-terminal extension has been identified. This Mr 25,000 bFGF has the same biological activity and the same affinity for the bFGF receptor as the typical Mr 18,000 bFGFs. The Mr 25,000 bFGF can be converted into an Mr 18,000 form by treatment with low concentrations of trypsin, suggesting that it may be a precursor to the Mr 18,000 bFGF.     

Fibroblast growth factor as an intraovarian hormone: differential regulation of steroidogenesis by an angiogenic factor

The potential role of fibroblast growth factor (FGF) in the regulation of granulosa cell differentiation was investigated because of its recent identification as the corpus luteum angiogenic factor. Treatment of rat ovarian granulosa cells with FGF inhibits the capacity of follicle stimulating hormone to stimulate estrogen production and to induce luteinizing hormone receptors. In contrast, although incubations with FGF can inhibit the estrogen-sensitive component of progesterone synthesis, the presence of FGF with suboptimal concentrations of follicle stimulating hormone significantly enhances the synthesis of progesterone. This capacity to differentially regulate steroidogenesis in the granulosa cell is comparable to the potency of FGF (ED50 = 30 pg/ml, 10(-12) M) in other in vitro assays. The observation that an angiogenic factor, like FGF, can specifically increase the sensitivity of progesterone synthesis and simultaneously inhibit estrogen formation supports the hypothesis that this growth factor plays an important role in the development and maintenance of a functional corpus luteum. As such, FGF may be involved in the local regulation of follicular selection, growth and atresia by simple virtue of its capacity to induce a neovascular response on one hand and by its ability to modulate the differentiated response to gonadotropins on the other.