Anaerobic Bacterial Flora of Intra-abdominal Infections and their Antimicrobial Susceptibility Pattern in Kuwait

Clinical samples obtained from 200 patients with intra-abdominal infections were investigated for the presence of anaerobic bacteria. The majority of samples were from patients with appendicitis (108, 54%) followed by peritoneal abscess/peritonitis (37, 18.5%). A total of 153 anaerobes were isolated from 83 culture positive specimens with an isolation rate of 1.8 per sample. Ninety (59%) yielded Bacteroides fragilis group and B. fragilis stricto sensu accounted for half of them. Other isolates were 36 (23.5%) Prevotella species and 15 (9.8%)Peptostreptococcus micros . The susceptibility of the 153 isolates against eight antibiotics was determined by the E-test. All the isolates were susceptible to metronidazole, MIC₉₀s varying between 1–2 μg/mL. ThePrevotella spp., Peptostreptococcus spp., Fusobacterium spp. and Porphyromonas spp. were all susceptible to clindamycin (MIC₉₀s=0.25–2 μg/mL respectively), imipenem (MIC₉₀s=0.12–0.5μg/mL respectively) and meropenem (MIC₉₀=0.25 μg/mL each). About 25% of the B. fragilis group were resistant to clindamycin with MIC more than 256 μg/mL. Piperacillin-tazobactam also exhibited excellent in vitro activity against all the isolates (MIC₉₀=0.25 μg/mL).     

Development and validation of a fluorogenic assay to measure separase enzyme activity

Separase, an endopeptidase, plays a pivotal role in the separation of sister chromatids at anaphase by cleaving its substrate cohesin Rad21. Recent study suggests that separase is an oncogene. Overexpression of separase induces aneuploidy and mammary tumorigenesis in mice. Separase is also overexpressed and mislocalized in a wide range of human cancers, including breast, prostate, and osteosarcoma. Currently, there is no quantitative assay to measure separase enzymatic activity. To quantify separase enzymatic activity, we have designed a fluorogenic assay in which 7-amido-4-methyl coumaric acid (AMC)-conjugated Rad21 mitotic cleavage site peptide (Ac-Asp-Arg-Glu-Ile-Nle-Arg-MCA) is used as the substrate of separase. We used this assay to quantify separase activity during cell cycle progression and in a panel of human tumor cell lines as well as leukemia patient samples.     

Variability of nutrients and phytoplankton biomass in a shallow brackish water ecosystem (Chilika Lagoon, India)

Seasonal and spatial variations in water quality parameters, such as nutrients [NH₄ ⁺–N, NO₂⁻–N, NO₃⁻–N, PO₄³⁻–P, total nitrogen (TN) and total phosphorus (TP)], Secchi disc depth, salinity, dissolved oxygen, chlorophyll a, primary productivity and phytoplankton standing stock, were studied in Chilika Lagoon (from 27 sampling locations) during 2001–2003 to assess the present ecological status. The study was undertaken after a major hydrological intervention in September 2000, which connected the lagoon body and the Bay of Bengal via a manmade opening (new mouth). Current and old data on water quality were also compared to establish the changes that had occurred after the hydrological intervention. Multivariate techniques and gridding methods were used to investigate the spatial and seasonal variability of the data and to characterize the trophic evolution of the basin. Results of principal component analysis (PCA) indicated that the 27 stations can be classified into five groups based on similarities in the temporal variation of nutrients, chlorophyll a concentration, salinity, and other physicochemical parameters. The tributaries and the exchange of lagoon water with the Bay of Bengal most probably determine the water quality and the dynamics of the ecosystem. Hydrodynamics of the lagoon, weed coverage, input of urban sewage through tributaries and agricultural runoff are probably the key factors controlling the trophic conditions of the lagoon. An increase in salinity and total phosphorus was noted after the new mouth was opened, while the total suspended sediment load, the water column depth, and nitrogenous nutrients decreased. The new mouth opening also brought changes in the phytoplankton species composition.     

Apoplasmic assimilates and grain growth of contrasting rice cultivars differing in grain dry mass and size

Apical dominance in assimilate filling impacts grain growth in basal spikelets of rice panicle. In this study, organic materials of the pericarp, apoplasmic space and endosperm of the apical and basal caryopses, and photosynthesis of the flag leaf were measured during early part of grain development in three types of rice cultivars with similar phenology, but difference in grain weight and size in the dry and wet seasons of 2006 and 2007, respectively. Photosynthetic activity of the flag leaf was consistently low in small-seeded cultivars. Rates of grain filling and cell division of endosperm and concentration of assimilates, starch, proteins and chlorophylls of the caryopsis were lower, but spikelet ethylene production and peroxidase activity were higher in a small-seeded cultivar compared to a big-seeded cultivar. Similar disparities in grain filling and other attributes were noticed for the inferior basal spikelets of the panicle compared to the superior apical spikelets, except the assimilate concentration of the pericarp and endosperm. Temporal fluctuation in assimilate concentration of the organs were similar between the cultivars. Concentration of apoplasmic assimilates mostly exhibited negative correlation with that of pericarp and endosperm. Compared to the apical spikelets, correlation was more negative for the basal spikelets. Conversely, correlation was positive between the concentration of apoplasmic assimilates and endosperm cell number and grain weight of the cultivars. Ethylene released from the spikelets at anthesis affected growth and cell division rates of endosperm and enhanced protein and chlorophyll degradation and peroxidase activity of the caryopsis. It was concluded that variation in spikelet ethylene production may be responsible for differences in size or weight of grains among rice cultivars and spikelets at different locations of the panicle. The concentration of apoplasmic assimilates could be an indicator for grain filling capacity, and ethylene regulated the concentration by affecting pericarp activity for assimilate unloading.     

Intranuclear accumulation of plant tubulin in response to low temperature

Summary. Concurrently with cold-induced disintegration of microtubular structures in the cytoplasm, gradual tubulin accumulation was observed in a progressively growing proportion of interphase nuclei in tobacco BY-2 cells. This intranuclear tubulin disappeared upon rewarming. Simultaneously, new microtubules rapidly emerged from the nuclear periphery and reconstituted new cortical arrays, as was shown by immunofluorescence. A rapid exclusion of tubulin from the nucleus during rewarming was also observed in vivo in cells expressing GFP-tubulin. Nuclei were purified from cells that expressed GFP fused to an endoplasmic-reticulum retention signal (BY-2-mGFP5-ER), and green-fluorescent protein was used as a diagnostic marker to confirm that the nuclear fraction was not contaminated by nuclear-envelope proteins. These purified, GFP-free nuclei contained tubulin when isolated from cold-treated cells, whereas control nuclei were void of tubulin. Furthermore, highly conserved putative nuclear-export sequences were identified in tubulin sequences. These results led us to interpret the accumulation of tubulin in interphasic nuclei, as well as its rapid nuclear export, in the context of ancient intranuclear tubulin function during the cell cycle progression. Correspondence and reprints: Department of Plant Physiology, Faculty of Science, Charles University, Viničná 5, 128 44 Prague 2, Czech Republic.     

NSs Encoded by Groundnut Bud Necrosis Virus Is a Bifunctional Enzyme

Groundnut bud necrosis virus (GBNV), a member of genus Tospovirus in the family Bunyaviridae, infects a large number of leguminosae and solanaceae plants in India. With a view to elucidate the function of nonstructural protein, NSs encoded by the small RNA genome (S RNA), the NSs protein of GBNV- tomato (Karnataka) [1] was over-expressed in E. coli and purified by Ni-NTA chromatography. The purified rNSs protein exhibited an RNA stimulated NTPase activity. Further, this activity was metal ion dependent and was inhibited by adenosine 5′ (β, γ imido) triphosphate, an ATP analog. The rNSs could also hydrolyze dATP. Interestingly, in addition to the NTPase and dATPase activities, the rNSs exhibited ATP independent 5′ RNA/DNA phosphatase activity that was completely inhibited by AMP. The 5′ α phosphate could be removed from ssDNA, ssRNA, dsDNA and dsRNA thus confirming that rNSs has a novel 5′ α phosphatase activity. K189A mutation in the Walker motif A (GxxxxGKT) resulted in complete loss of ATPase activity, but the 5′ phosphatase activity was unaffected. On the other hand, D159A mutation in the Walker motif B (DExx) resulted in partial loss of both the activities. These results demonstrate for the first time that NSs is a bifunctional enzyme, which could participate in viral movement, replication or in suppression of the host defense mechanism.     

Elevational gradients of reptile richness in the southern Western Ghats of India: Evaluating spatial and bioclimatic drivers

Exploring elevational patterns in species richness and their underlying mechanisms is a major goal in biogeography and community ecology. Reptiles can be powerful model organisms to examine biogeographical patterns. In this study, we examine the elevational patterns of reptile species richness and test a series of hypotheses that may explain them. We sampled reptile communities along a tropical elevational gradient (100–1,500 m a.s.l.) in the Western Ghats of India using time‐constrained visual encounter surveys at each 100‐m elevation zone for 3 years. First, we investigated species richness patterns across elevation and the support of mid‐domain effect and Rapoport's rule. Second, we tested whether a series of bioclimatic (temperature and tree density) and spatial (mid‐domain effect and area) hypotheses explained species richness. We used linear regression and AICc to compare competing models for all reptiles, and each of the subgroups: snakes, lizards, and Western Ghats’ endemics. Overall reptile richness and lizard richness both displayed linear declines with elevation, which was best explained by temperature. Snake richness and endemic species richness did not systematically vary across elevation, and none of the potential hypotheses explained variation in them. This is the first standardized sampling of reptiles along an elevational gradient in the Western Ghats, and our results agree with the global view that temperature is the primary driver of ectotherm species richness. By establishing strong reptile diversity–temperature associations across elevation, our study also has implications for the impact of future climate change on range‐restricted species in the Western Ghats.