Use of diethyldithiocarbamate for quantitative determination of tellurite uptake by bacteria.

We have developed a simple method for the quantitative determination of tellurite in biological media. This assay is suitable for studying tellurite uptake in bacteria and overcomes the problems of older techniques which are time consuming and labor intensive. In earlier protocols diethyldithiocarbamate was reacted with tellurite and the resulting complex was extracted into organic solvents before spectrophotometric determination. In this study, diethyldithiocarbamate was incubated with tellurite at neutral pH to form a yellow colloidal solution. The absorbance of the aqueous yellow sol was used to determine tellurite concentrations in the range of 1 to 50 micrograms/ml (4 to 200 microM) without the need for solvent extraction.     

The effects of salt stress and arbuscular mycorrhiza on plant neighbour effects and self-thinning

Abiotic and biotic factors can alter the nature and strength of plant–plant interactions and therefore self-thinning (density-dependent mortality), but few studies have looked at how such factors interact. We investigated how salt stress and arbuscular mycorrhizal fungi (AMF) influence plant neighbour effects and self-thinning in experimental populations of Medicago sativa. We obtained two mycorrhizal levels by applying the fungicide benomyl (low AMF) or not (high AMF) at three salinity levels (0.05%, 0.2% and 0.5%). In experiment 1, we investigated how salinity and AMF interact to influence plant interaction intensity using a neighbour removal treatment. In experiment 2, we investigated how self-thinning dynamics vary under salinity conditions and different AMF levels at two initial plant densities (6000 and 17,500 seeds m^?2). Shoot biomass and plant density were measured 30, 60 and 90 days after sowing. Standardized major axis regression was used to estimate self-thinning parameters. In experiment 1, AMF increased competitive plant neighbour effects when there was no salinity stress, but this enhancement was not significant with increasing salinity. In experiment 2, there were effects of salinity and AMF on the self-thinning trajectory. The slope of the log (mean shoot biomass per unit area) vs. log density relationship was significantly steeper for the high AMF treatment than for the low AMF treatment without salinity, but the effect of AMF level on the self-thinning exponent was not significant under the two higher salinity levels. The effect of AMF treatments on the intercept of the self-thinning line was not significant at 0.2% salinity but was significant at 0.5% salinity, higher elevation for high AMF treatment. In self-thinning populations, AMF decreased the survival rate without salinity, but increased the survival rate at the highest salinity level. Our results support the hypothesis that salinity and AMF interact to influence plant neighbour effects and self-thinning. Under no-salinity conditions, AMF increased competition, steepened the self-thinning line and decreased survival rate, but these effects of AMF were not significant in the presence of salinity.     

Circadian and seasonal rhythms of 5-HT receptor subtypes, membrane anisotropy and 5-HT release in hippocampus and cortex of the rat.

Specific serotonin binding (5-HT1, 5-HT1A, and 5-HT2 subtypes) and membrane anisotropy were measured at 2 h intervals over a 24 h period in the hippocampus and cortex of Wistar WU rats, housed under a 12 h light-dark cycle, with lights on at 07.00. All experiments were performed both in March and December. In the hippocampus significant circadian rhythms could be ascertained for 5-HT1 binding sites in March and December while for 5-HT1A (subtype of 5-HT1) binding sites the circadian rhythm was only significant in March. The membrane anisotropy also showed significant variations only in March. Circadian rhythms were also found in the cortex for 5-HT1 (December) and 5-HT2 (March and December) binding sites as well as for the membrane anisotropy (December). A correlation was found between membrane anisotropy and 5-HT1 and 5-HT2 binding sites in hippocampus and cortex, respectively. A circadian rhythmicity was also observed for serotonin release as measured by in vivo voltammetry in both brain areas. The results obtained on the diurnal variations of serotonin receptor subtypes and serotonin release and the probable inverse relationship of these two parameters may be relevant in understanding the coupling of pre- and postsynaptic activity.     

Size-asymmetric root competition in deep,nutrient-poor soil

Aims There is much evidence that plant competition below ground is size symmetric, i.e. that competing plants share contested resources in proportion to their sizes. Several researchers have hypothesized that a patchy distribution of soil nutrients could result in size-asymmetric root competition. We tested this hypothesis.     

The potential role of cofilin-1 in promoting triple negative breast cancer (TNBC) metastasis via the extracellular vesicles (EVs)

Triple negative breast cancer (TNBC) is an aggressive cancer, particularly prone to metastasis and is associated with poor survival outcomes. The key to unravelling the aggressiveness of TNBC lies in decoding the mechanism by which it metastasises. Cofilin-1 is a well-studied member of the cofilin family, involved in actin depolymerisation. Studies have described the diverse roles of cofilin-1 including cell motility, apoptosis and lipid metabolism. Levels of cofilin-1 have been shown to be increased in many different types of malignant cells, with increased cofilin-1 protein levels associated with poor prognosis in patients with TNBC. Extracellular vesicles (EVs) are microvesicles typically around 100 nm in size, found in all biological fluids examined to date (Lötvall et al., 2014). Proteomic studies on extracellular vesicles (EVs) have shown that cofilin-1 is amongst the most frequently detected. Moreover, decreased levels of cofilin-1 potentially inhibit the release of EVs from cells. Additionally, Cofilin-1 is essential for the maturation of EVs and may also play a key role in the establishment of the pre-metastatic niche, thus promoting tumour cell migration. Further work into the exact mechanism by which cofilin-1 advances TNBC metastasis, may potentially prevent disease progression and improve outcomes for patients with TNBC.     

Detection and characterization of chitinases and other chitin-modifying enzymes

Multiple industrial and medical uses of chitin and its derivatives have been developed in recent years. The demand for enzymes with new or desirable properties continues to grow as additional uses of chitin, chitooligosaccharides, and chitosan become apparent. Microorganisms, the primary degraders of chitin in the environment, are a rich source of valuable chitin-modifying enzymes. This review summarizes many methods that can be used to isolate and characterize chitin-modifying enzymes including chitin depolymerases, chitodextrinases, chitin deacetylases, N-acetylglucosaminidases, chitin-binding proteins, and chitosanases. Chitin analogs, zymography, detection of reducing sugars, genomic library screening, chitooligosaccharide electrophoresis, degenerate PCR primer design, thin layer chromatography, and chitin-binding assays are discussed.