Nonhistone chromatin proteins of B-lymphocytes stimulated by lipopolysaccharide Two-dimensional gel electrophoresis analysis of proteins synthesized and phoshorylated during the initiation of lymphocyte differentiation

Synthesis and phosphorylation of nonhistone chromatin and nucleoplasmic proteins during the first 24 h of activation of mouse B-lymphocytes by the B-cell mitogen lipopolysaccharide have been studied by two-dimensional gel electrophoretic analysis. Although little change occurs in the nucleoplasmic proteins, it has been shown that the incorporation of [³⁵S]methionine into nonhistone chromatin proteins is selectively stimulated. The degree of stimulation and the kinetics of synthesis are characteristic for each individual protein; some proteins exhibit increased incorporation only 4 h after addition of mitogen, while others are synthesized de novo between 8 and 24 h. After 72 h stimulation, the majority of nonhistone chromatin protein synthesis occurs in the highly differentiated lymphoblasts and plasma cells actively secreting IgM, very little synthesis taking place in the small lymphocytes. Analysis of nuclear proteins from lymphocytes stimulated for 2 h showed no selective stimulation of phosphorylation. These observations suggest that nonhistone chromatin proteins play an important role in the regulation of gene expression in B-lymphocytes.     

Influence of the annual flood-pulse on catch per unit effort,condition and reproduction of Clarias gariepinus from the upper Okavango Delta,Botswana

Catch per unit effort (CPUE), length, weight and maturity data for Clarias gariepinus were collected during monthly gillnet surveys in the upper Okavango Delta between 2001 and 2009 to investigate their relationship with the annual flood-pulse. CPUE, condition factor (K) and the proportion of ripe-running fish (P_RR) in the population followed a unimodal annual cycle that could be modelled using water temperature and flood-pulse hydrology. Increased CPUE during declining water levels was most likely a result of feeding migrations and aggregation behaviour. The observed increase in K during low floods in October and November preceded the increase in P_RR, which increased mainly with increasing temperature but appeared less dependent on flow. This study provided quantitative evidence that the biology of fish in the Okavango Delta is mainly dependent on the annual flood regime and, therefore, that conservation efforts should be focused on maintaining natural flow patterns in the face of climate change and potential water extraction schemes upstream.     

Anthocyanins in Salix species: A new anthocyanin in salix purpurea bark

Cyanidin 3-glucoside and delphinidin 3-glucoside (minor component) occurred in the bark of Salix purpurea (29 cultivars examined), S. fragilis (3 cvs), S. americana (4 cvs), S. rubra (1 cv.), S. incana (1 cv.), S. aegyptica (1 cv.) and S. alba (3 cvs) and several hybrids. A previously unrecorded anthocyanin was also present in appreciable amounts in the bark of eleven S. purpurea cultivars, notably those with small leaves. In other large-leaved cultivars of S. purpurea (18) it occurred only in traces or was not detected with certainty. A trace was found in one purpurea hybrid, but it was not detected in four others. Small amounts of the new anthocyanin were also found in S. incana (1 cv.), S. fragilis cv. Basfordiana, S. americana cv. Cordata and one hybrid, but were absent from other cultivars of S. fragilis (2) and S. americana (2), and also from S. alba (3), S. aegyptica (1), S. daphnoides (1), S. rubra (1), S. triandra (1), S. viminalis (1) and three hybrids. The new anthocyanin is unique in containing fructose as well as glucose and is based upon a previously undescribed anthocyanidin, possibly dimeric in nature, which is provisionally named purpurinidin.