Isolation and characterization of acetonitrile utilizing bacteria

Summary Bacteria utilizing high concentrations of acetonitrile as the sole carbon source were isolated and identified asChromobacterium sp. andPseudomonas aeruginosa. Maximum growth was attained after 96 h of incubation andP. aeruginosa grew slightly faster thanChromobacterium sp. The strains were able to grow and oxidize acetonitrile at concentrations as high as 600 mM. However, higher concentrations inhibited growth and oxygen uptake. Degradation studies with (¹⁴C)acetonitrile indicated 57% of acetonitrile was degraded byPseudomonas aeruginosa as compared to 43% byChromobacterium. The isolates utilized different nitrile compounds as carbon substrates.     

Sulphated heteropolysaccharides from Padina pavonia

Extraction with hydrochloric acid (pH 2.5) of the brown alga Padina pavonia afforded water-soluble and water-insoluble polysaccharides comprising D-glucuronic acid, L-fucose, D-xylose, D-mannose, D-glucose and D- galactose residues. The water-soluble polysaccharide was fractionated by using ethanol, and cetylpyridinium chloride and by chromatography on DEAE-cellulose. A neutral laminaran-like glucan, a sulphated heteropolysaccharide composed of the aforementioned sugars and a protein moiety were obtained. The isolated heteropolysaccharide showed high anticoagulation activity.     

Human monocytes augment invasiveness and proteolytic activity of inflammatory breast cancer

Abstract Inflammatory breast cancer (IBC) is the most aggressive form of breast cancer, and here, we examined in vitro the interactions between the human IBC cell line SUM149 and U937 human naive monocytes. We found an altered morphology, enhanced invasiveness and proteolytic activity of SUM149 cells when cultured with U937 cells or in U937-conditioned media (U937-CM). Increases in expression and activity of the cysteine protease cathepsin B and expression of caveolin-1 were also detected in SUM149 cells grown in U937-CM, thus suggesting a contribution of these proteins to the augmented invasion through and proteolysis of the extracellular matrix by the IBC cells.     

A queueing model for predicting message latency in uni-directional <Emphasis Type="Italic">k</Emphasis>-ary <Emphasis Type="Italic">n</Emphasis>-cubes with deterministic routing and non-uniform traffic

The interconnection network is one of the key architectural components in any parallel computer. The distribution of the traffic injected into the network is among the factors that greatly influences network performance. The uniform traffic pattern has been adopted in many existing network performance evaluation studies due to the tractability of the resulting analytical modelling approach. However, many real applications exhibit non-uniform traffic patterns such as hot-spot traffic. K-ary n-cubes have been the mostly widely used in the implementation of practical parallel systems. Extensive research studies have been conducted on the performance modelling and evaluation of these networks. Nonetheless, most of these studies have been confined to uniform traffic distributions and have been based on software simulation. The present paper proposes a new stochastic model to predict message latency in k-ary n-cubes with deterministic routing in the presence of hot-spot traffic. The model has been validated through simulation experiments and has shown a close agreement with simulation results.

Vegetative compatibility and phenotypic characterization as a means of determining genetic diversity of Aspergillus flavus isolates

Toxigenic Aspergillus species produce mycotoxins that are carcinogenic, hepatotoxic and teratogenic immunosuppressing agents in both human and animals. Kenya frequently experiences outbreaks of aflatoxicosis with the worst occurring in 2010, which resulted in 215 deaths. We examined the possible reasons for these frequent aflatoxicosis outbreaks in Kenya by studying Aspergillus flavus diversity, phenotypes and mycotoxin profiles across various agricultural regions. Using diagonal transect random sampling, maize kernels were collected from Makueni, Homa Bay, Nandi, and Kisumu counties. Out of 37 isolates, nitrate non-utilizing auxotrophs complementation test revealed 20 vegetative compatibility groups. We designated these groups by the prefix “KVCG”, where “K” represented Kenya and consequently assigned numbers 1–20 based on our findings. KVCG14 and KVCG15 had highest distribution frequency (n = 13; 10.8 %). The distribution of the L-, S- and S-/L-morphotypes across the regions were 57 % (n = 21); 7 % (n = 3) and 36 % (n = 13), respectively. Furthermore, a unique isolate (KSM015) was identified that had characteristics of S-morphotype, but produced both aflatoxins B and G. Coconut agar medium (CAM) assay, TLC and HPLC analyses confirmed the presence or absence of aflatoxins in selected toxigenic and atoxigenic isolates. Diversity index (H′) analyses ranged from 0.11 (Nandi samples) to 0.32 (Kisumu samples). Heterokaryon compatibility ranged from 33 % (for the Makueni samples, n = 3) to 67 % (Nandi samples, n = 6). To our knowledge, this is the first reported findings for A. flavus diversity and distribution in Nandi, Homa Bay and Kisumu counties and may assist current and future researchers in the selection of biocontrol strategies to mitigate aflatoxin contamination as has been researched in Makueni and neighbouring counties.     

Androgen receptors in coeliac ganglion in late pregnant rat

The ovarian function is controlled by endocrine factors and neural influence. In late pregnant rat, androstenedione, from the coeliac ganglion, has a luteotrophic effect in the ex vivo coeliac ganglion-superior ovarian nerve-ovary system. In this work we investigate the presence of androgen receptors in the coeliac ganglion of late pregnant rats by immunohistochemistry. We also explore, from a physiological point of view, the potential participation of these receptors in the androstenedione ganglionic action on progesterone release and metabolism, as well as on nitrites release in the ovary compartment. The coeliac ganglion was isolated after being fixed in situ and immunohistochemistry was performed. In the system, three experimental groups were used with the addition of (a) androstenedione, (b) flutamide, and (c) androstenedione plus flutamide in the ganglion compartment. Progesterone and nitrite concentrations were determined in the ovary compartment at different incubation times. Corpora lutea samples isolated at the end of incubation were used to determine the expressions and activities of the progesterone synthesis (3β-hydroxysteroid-dehydrogenase, 3β-HSD) and degradation (20α-hydroxysteroid-dehydrogenase, 20α-HSD) enzymes. Immunohistochemistry revealed cytoplasmatic androgen receptor immunoreactivity in neural somas in the coeliac ganglion. In the coeliac ganglion-superior ovarian nerve-ovary system, androstenedione addition increased 3β-HSD and decreased 20α-HSD, showed a tendency to decrease 20α-HSD expression, and increased nitrites release in relation to control. Androstenedione plus flutamide decreased progesterone and nitrites release in relation to the androstenedione group. This work demonstrates the presence of androgen receptors in neurons of celiac ganglion and provides evidence for the luteotrophic action of androstenedione via a neural pathway that may be mediated by these receptors.     

Influence of force fields on the selective diffusion of para-xylene over ortho-xylene in 10-ring zeolites

A molecular dynamics study of diffusion of p-xylene and o-xylene has been performed over three different pure silica 10-ring zeolites, MFI, SFG and TUN. The shape selective properties of the frameworks of these three materials have been tested using four different types of force fields commonly used based on united atom, rigid-ion and core-shell approximations. The performance of each force field is analysed in order to find which force fields can give sufficiently accurate estimations that allow to select appropriate zeolites for selective separation of para/ortho xylene. This performance was found to depend on the quality of the structural properties of the zeolite, in particular the size and shape of the 10 rings which act as bottlenecks for the diffusion. The computational results allow us to define some optimum characteristics for the selective diffusion of p-xylene.