PHASED DIVISION OF PERIDINIUM CINCTUM F. WESTII (DINOPHYCEAE) AND DEVELOPMENT OF THE LAKE KINNERET (ISRAEL) BLOOM1,2

The yearly bloom of Peridinium cinctum f. westii (Lemm.) Lef. in Lake Kinneret is described and compared with the distribution of dinoflagellates in other freshwater bodies. The physical conditions required by the Wyatt and Horwood model do not fit the actual physical events accompanying the onset of the bloom. In situ measurements of the percentage of cells in division were undertaken to clarify various points about the internal dynamics of the population. The exponential increase of the population occurs when the diurnal percentage of cells in division is not higher than 10–15%. This percentage increases up to 45% in late February–March, but does not cause any increase of population. At this period, the loss rate is nearly equal to the rate of cell increase and is interpreted as massive mortality.     

Characterization of the proteins encoded by the Bacillus subtilis yoxA-dacC operon

In Bacillus subtilis , the yoxA and dacC genes were proposed to form an operon. The yoxA gene was overexpressed in Escherichia coli and its product fused to a polyhistidine tag was purified. An aldose-1-epimerase or mutarotase activity was measured with the YoxA protein that we propose to rename as GalM by analogy with its counterpart in E. coli . The peptide d -Glu-δ- m -A₂pm- d -Ala- m -A₂pm- d -Ala mimicking the B. subtilis and E. coli interpeptide bridge was synthesized and incubated with the purified dacC product, the PBP4a. A clear dd -endopeptidase activity was obtained with this penicillin-binding protein, or PBP. The possible role of this class of PBP, present in almost all bacteria, is discussed.     

Myelofibrosis involving lymph node: a novel cytogenetic abnormality in a mimicker of mesenchymal neoplasm

A case of primary myelofibrosis involving lymph node and with a novel cytogenetic abnormality [del (18) (p11.2-3)] is reported. The abnormalities are identical among specimens from the lymph node, peripheral blood, and bone marrow that were analyzed years apart. Additionally, we show that the infiltrate by dysplastic megakaryocytes in the lymph node morphologically mimics a metastatic mesenchymal neoplasm, even when the clinical history myelofibrosis was known.     

Carbohydrate fermentation and by-product absorption studied with labelled cellulose in Oryctes nasicornis larvae (Coleoptera:Scarabaeidae)

Isolated gut segments of Oryctes nasicornis larvae were incubated in vitro after injection with ¹⁴C-cellulose. The incubation medium became progressively richer in labelled volatile fatty acids (VFA), demonstrating the process of cellulolysis and the absorption of carbohydrate degradation products. The mesenteron and the proctodeal dilation were both shown to be sites of cellulolysis and VFA absorption. The major acid formed and absorbed was acetic acid which, in the absence of any detectable glucose, would seem to constitute the essential product of carbon metabolism in Oryctes larvae as in ruminant mammals. The cellulolytic capacities of the different intestinal segment were tested and compared to each other.     

Activation of phospholiphase C by different effectors in rat placental cells

The present communication documents the accumulation of inositol phosphates in rat placental cells by fluoride as well as by vanadate. These findings suggest the existence of the phosphoinositide pathway and its modulation by a G-protein. A concomitant action of fluoride on phosphoinositide breakdown was also observed. As is often the case in intact cells from different organs, protein kinase C exerts a feeback regulatory control on this signalling system. Gonadotropin-releasing hormone (GnRH) also stimulated the accumulation of inositol phosphates in cultured cells but no effect could be detected in freshly isolated cells. Therefore, the phosphoinositide pathway seems to be involved in the mechanism of action of GnRH in rat placental cells.