Effects of Sewage Dumping on Macrobenthic Invertebrates in the Jordan Gulf of Aqaba,Red Sea

There are two sewage outfalls along the Jordanian coastline in the Gulf of Aqaba. During 1982 and 1983 a total of 328 core samples (0.01 m² to a depth of 15 cm) were collected from the two outfalls, two control stations which resemble the outfalls in depth and sediment texture, and from two stations 100 m on both sides of each outfall. Faunal analysis revealed that the total number of individuals, number of species, species richness, and faunal similarities of macrobenthic invertebrates were lower at the sewage outfall near the phosphate loading port than the control station during both collections. At the 100 m stations, the numbers of individuals were generally higher than the sewage and control stations. The number of species, however, was highest at the control station and lowest at the sewage outfall. At the other sewage outfall, where the sewage effluent is discharged sporadically, no measurable effects on macrobenthic invertebrates were found.     

Drosophila citron kinase is required for the final steps of cytokinesis

The mechanisms underlying completion of cytokinesis are still poorly understood. Here, we show that the Drosophila orthologue of mammalian Citron kinases is essential for the final events of the cytokinetic process. Flies bearing mutations in the Drosophila citron kinase (dck) gene were defective in both neuroblast and spermatocyte cytokinesis. In both cell types, early cytokinetic events such as central spindle assembly and contractile ring formation were completely normal. Moreover, cytokinetic rings constricted normally, leading to complete furrow ingression. However late telophases of both cell types displayed persistent midbodies associated with disorganized F actin and anillin structures. Similar defects were observed in dck RNA interference (RNAi) telophases, which, in addition to abnormal F actin and anillin rings, also displayed aberrant membrane protrusions at the cleavage site. Together, these results indicate that mutations in the dck gene result in morphologically abnormal intercellular bridges and in delayed resolution of these structures, suggesting that the wild-type function of dck is required for abscission at the end of cytokinesis. The phenotype of Dck-depleted cells is different from those observed in most Drosophila cytokinesis mutants but extraordinarily similar to that caused by anillin RNAi, suggesting that Dck and anillin are in the same pathway for completion of cytokinesis.     

Inhibin/activin subunits alpha, beta-A and beta-B are differentially expressed in normal human endometrium throughout the menstrual cycle

Inhibins are dimeric glycoproteins composed of an alpha (alpha) subunit and one of two possible beta (beta-) subunits (betaA or betaB). The aims of this study were to assess the frequency and tissue distribution patterns of the inhibin subunits in normal human endometrium. Samples from human endometrium from proliferative phase (PP; n=32), early secretory phase (ES; n=10) and late secretory phase (LS; n=12) were obtained. Immunohistochemistry, immunofluorescence and a statistical analysis were performed. All three inhibin subunits were expressed by normal endometrium by immunohistochemistry and immunofluorescence. Inhibin-alpha was primarily detected in glandular epithelial cells, while inhibin-beta subunits were additionally localised in stromal tissue. Inhibin-alpha staining reaction increased significantly between PP and ES (P<0.05), PP and LS (P<0.01), and ES and LS (P<0.02). Inhibin-betaA and -betaB were significant higher in LS than PP (P<0.05) and LS than ES (P<0.05). All three inhibin subunits were expressed by human endometrium varying across the menstrual cycle. This suggests substantial functions in human implantation of inhibin-alpha subunit, while stromal expression of the beta subunits could be important in the paracrine signalling for adequate endometrial maturation. The distinct expression in human endometrial tissue suggests a synthesis of inhibins into the lumen and a predominant secretion of activins into the stroma.     

Modulation of intracellular calcium concentrations and T cell activation by prickly pear polyphenols

Opuntia ficus indica (prickly pear) polyphenolic compounds (OFPC) triggered an increase in [Ca2+]i in human Jurkat T-cell lines. Furthermore, OFPC-induced rise in [Ca2+]i was significantly curtailed in calcium-free buffer (0% Ca2+) as compared to that in 100% Ca2+ medium. Preincubation of cells with tyrphostin A9, an inhibitor of Ca2+ release-activated Ca2+ (CRAC) channels, significantly diminished the OFPC-induced sustained response on the increases in [Ca2+]i. Lanthanum and nifedipine, the respective inhibitors of voltage-dependent and L-type calcium channels, failed to curtail significantly the OFPC-induced calcium response. As OFPC still stimulated increases in [Ca2+]i in 0% Ca2+ medium, the role of intracellular calcium was investigated. Hence, addition of thapsigargin (TG), an inhibitor of Ca2+-ATPase of the endoplasmic reticulum (ER), during the OFPC-induced peak response exerted an additive effect, indicating that the mechanism of action of these two agents are different. Furthermore, U73122, an inhibitor of IP3 production, completely abolished increases in [Ca2+]i, induced by OFPC, suggesting that these polyphenols induce the production of IP3 that recruits calcium from ER pool. Polyphenolic compounds do act extracellularly as addition of fatty acid-free bovine serum albumin (BSA) significantly diminished the rise in [Ca2+]i evoked by the formers. OFPC also induced plasma membrane hyperpolarisation which was reversed by addition of BSA. OFPC were found to curtail the expression of IL-2 mRNA and T-cell blastogenesis. Together these results suggest that OFPC induce increases in [Ca2+]i via ER pool and opening of CRAC channels, and exert immunosuppressive effects in Jurkat T-cells.     

Representing and analysing molecular and cellular function using the computer

Determining the biological function of a myriad of genes, and understanding how they interact to yield a living cell, is the major challenge of the post genome-sequencing era. The complexity of biological systems is such that this cannot be envisaged without the help of powerful computer systems capable of representing and analysing the intricate networks of physical and functional interactions between the different cellular components. In this review we try to provide the reader with an appreciation of where we stand in this regard. We discuss some of the inherent problems in describing the different facets of biological function, give an overview of how information on function is currently represented in the major biological databases, and describe different systems for organising and categorising the functions of gene products. In a second part, we present a new general data model, currently under development, which describes information on molecular function and cellular processes in a rigorous manner. The model is capable of representing a large variety of biochemical processes, including metabolic pathways, regulation of gene expression and signal transduction. It also incorporates taxonomies for categorising molecular entities, interactions and processes, and it offers means of viewing the information at different levels of resolution, and dealing with incomplete knowledge. The data model has been implemented in the database on protein function and cellular processes 'aMAZE' (http://www.ebi.ac.uk/research/pfbp/), which presently covers metabolic pathways and their regulation. Several tools for querying, displaying, and performing analyses on such pathways are briefly described in order to illustrate the practical applications enabled by the model.     

Photoreversible modulators of Escherichia coli beta-galactosidase. 1-Benzoyl-1-cyano-2-(4,5-dimethoxy-2-nitrophenyl)-ethene and 1,1-dicyano-2-(4,5-dimethoxy-2-nitrophenyl)-ethene

-Galactosidase (EC 3.2.1.23) is known to be inhibited by some thiol reagents. 1-Benzoyl-1-cyano-2-(4,5-dimethoxy-2-nitrophenyl)-ethene (1) was shown to be an irreversible inhibitor, while 1, 1-dicyano-2-(4,5-dimethoxy-2-nitrophenyl)-ethene (2) was demonstrated as a positive irreversible modulator causing a rise of up to 186% in -galactosidase activity. Compound 2 is, however, an irreversible inhibitor of the cysteine proteinase papain (preceding paper). Kinetic values of -galactosidase at pH 8.3 with o-nitrophenyl -D-galactopyranoside (ONPG) as the substrate and for compounds 1 and 2 were determined and in view of model experiments, it was assumed that both compounds possibly reacted with the thiol side chain of Cys in the active site inducing allosteric changes in the enzyme. Since the enzyme, modified by compound 1 or 2, was a 2-nitrobenzyl derivative, near-UV irradiation resulted in a recovery of up to 91% and a reduction of the enzyme's activity to 90%, respectively.     

Impaired trafficking of mutants of lysosomal glucocerebrosidase in Gaucher's disease

Gaucher's disease is the most inherited lysosomal storage disorder. Except for a few cases, the broad phenotypic heterogeneity of Gaucher's disease can be neither predicted from defined mutations nor from differences in residual enzyme activity. Here, we analyse the intracellular trafficking of glucocerebrosidase as an underlying mechanism for the expression of the clinical phenotype. Biosynthetic labeling studies combined with immunofluorescence analyses with fibroblasts from patients with the defined mutations N370S, L444P, D409H and G202R unequivocally demonstrate a retarded transport of glucocerebrosidase carrying the mutation N370S and a transport block in the ER of the enzyme with the mutations G202R, L444P and D409H. We asked whether cellular components in the patients' fibroblasts other than glucocerebrosidase are implicated in the onset of the disease. For this, mutant cDNA's corresponding to the phenotypes N370S, G202R and L444P were expressed in the mouse fibroblasts NIH3T3. Essentially similar biochemical and cellular features were revealed as compared to the patients' fibroblasts strongly suggesting that these mutations are exclusively responsible for the characterized phenotypes. Interestingly, the immunoglobulin binding protein (BiP) binds wild type and the mutant N370S but not the G202R and L444P variants suggesting a discriminatory role played by this chaperone associated with the severity of the disease.     

Functional analysis of cells obtained from bronchoalveolar lavage fluid (BALF) of lung cancer patients

BALF from tumor segments provides access to immune system cells in contact with lung tumors. We analyzed BALF cells as to their production of H2O2 and NO, comparing tumor-affected to non-affected lung segments. Twelve patients were studied (4 NSCLC, 3 SCC, 5 Adenocarcinoma). The cell numbers recovered from BALF varied, and, in adenocarcinoma patients, smaller numbers were recovered from tumor-affected segments. H2O2 production (up to 6.3 nmoles/2x10(5)cells) was obtained in 7/12 patients and, in these, it was more frequent in non-affected segments (7/7) than in affected segments (2/7). After culture, NO production was observed in three patients (6 to 314 microM) that also produced H2O2. These functional characteristics of cells in contact with neoplasia may have a role in determining the fate of the interactions between the immune system and lung cancer.     

Vibrio parahaemolyticus thermostable direct hemolysin can induce an apoptotic cell death in Rat-1 cells from inside and outside of the cells

Rat-1 cells exposed to Vibrio parahaemolyticus thermostable direct hemolysin (TDH) developed morphological changes including shrinkage of the cells and reduction in the size of nuclei. Cells either microinjected with TDH or transfected with the tdh gene also showed morphological changes similar to those induced by externally added toxin. Furthermore, TDH-exposed or tdh-transfected cells both showed chromatin condensation and DNA fragmentation which suggest cells undergoing apoptosis. In contrast, expression of a TDH mutant (R7) did not reveal any cytotoxic effects. We demonstrate that expressed TDH was distributed in the cytoplasm. The interleukin-1beta-converting enzyme-related protease inhibitor ZVAD-FMK did not inhibit TDH cytotoxicity. Our results suggest that TDH can induce its cytotoxicity both from outside and from inside the cells and killed the cells through apoptosis.