Export and functions of sphingosine-1-phosphate

The sphingolipid metabolite, sphingosine-1-phosphate (S1P), has emerged as a critical player in a number of fundamental biological processes and is important in cancer, angiogenesis, wound healing, cardiovascular function, atherosclerosis, immunity and asthma, among others. Activation of sphingosine kinases, enzymes that catalyze the phosphorylation of sphingosine to S1P, by a variety of agonists, including growth factors, cytokines, hormones, and antigen, increases intracellular S1P. Many of the biological effects of S1P are mediated by its binding to five specific G protein-coupled receptors located on the cell surface in an autocrine and/or paracrine manner. Therefore, understanding the mechanism by which intracellularly generated S1P is released out of cells is both interesting and important. In this review, we will discuss how S1P is formed and released. We will focus particularly on the current knowledge of how the S1P gradient between tissues and blood is maintained, and the role of ABC transporters in S1P release.     

Should the brain be regarded as a computer?

In recent years analogies between thinking processes and computer mechanisms have been pointed out. There exist, however, also considerable differences between higher cerebral activities and computers. It seems, therefore, hazardous to consider the human brain exclusively as a computer.     

Use of chitin for controlling plant plant-parasitic nematodes

Summary Bean and tomato seedlings, treated with different amounts of ammonia and chitin, and inoculated with the root-knot nematode,Meloidogyne javanica, were reared in two consecutive 35-day growth of shoot and root and the condition of the root systems of both plant species and degree of infection byM. javanica were decreased by increasing amounts of ammonia. Chitin caused a relatively small reduction in gall formation but almost no changes in fresh shoot weights. The effect of chitin on plant growth and nematode attack were also compared in irradiated and non-irradiated soil. In the first cycle galling index of the chitin treated plant was similar to that of untreated plants maintained in the irradiated soil conditions, while in the non-irradiated soil, chitin treatment reduced galling index. In the second cycle, chitin treatment reduced galling index in both irradiated and non-irradiated soils, especially in the latter, where galling index greatly decreased compared with the non-treated plants. Differences in fresh shoot weight between nematode-infected and nematode-free plants amended with chitin were greater under non-irradiated than irradiated conditions, especially in the second cycle. In non-irradiated soil, a higher level of chitinolytic microorganisms, particularly actinomycetes, was found in the second cycle. Contribution from the Agricultural Research Organization (ARO), Bet Dagan, Israel. No. 1520-E, 1985 series.     

Obligate amoebae of the protostelids: significance for the concept of Eumycetozoa

Most flagellate Eumycetozoa have a non-flagellate, or obligately amoeboid, trophic state which differentiates from the amoebo-flagellate state and gives rise to the fruiting body. This study examines the morphology, general ultrastructure, and microtubular systems of the obligate amoebae of three flagellate protostelids with typical amoebo-flagellate states. The obligate amoebae of all three species are morphologically distinct indicating that the obligately amoeboid state has evolved independently in the history of each species. Therefore, obligate amoebae may be useful for defining separate evolutionary groups within the Eumycetozoa.     

Über die Chemorezeption von Crangon vulgaris Fabr

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