Differential effects of cholesterol and 7-dehydrocholesterol on ligand binding of solubilized hippocampal serotonin1A receptors: implications in SLOS

The serotonin1A receptor is an important member of the G-protein coupled receptor family, and is involved in the generation and modulation of a variety of cognitive, behavioral, and developmental functions. Solubilization of the hippocampal serotonin1A receptor by 3-[(3-cholamidopropyl)-dimethylammonio]-1-propanesulfonate (CHAPS) is accompanied by loss of membrane cholesterol which results in a reduction in specific agonist binding activity. Replenishment of cholesterol to solubilized membranes restores the cholesterol content of the membrane and significantly enhances specific agonist binding activity. In order to test the stringency of the requirement of cholesterol in this process, we solubilized native hippocampal membranes followed by replenishment with 7-dehydrocholesterol (7-DHC). 7-DHC is an immediate biosynthetic precursor of cholesterol differing only in a double bond at the 7th position in its sterol ring. Our results show, for the first time, that replenishment of solubilized hippocampal membranes with 7-DHC does not restore ligand binding activity of the serotonin1A receptor, in spite of recovery of the overall membrane order. This observation shows that the requirement for restoration of ligand binding activity is more stringent than the requirement for the recovery of overall membrane order. These novel results have potential implications in understanding the interaction of membrane sterols with this important neuronal receptor under pathogenic conditions such as the Smith-Lemli-Opitz syndrome.     

Effect of light and media upon growth and melanin formation in aureobasidium pullulans (de By.)Arn. (=pullularia pullulans)

Summary Polysaccharides like dextrine and starch are shown to be the best carbon sources for the growth ofAureobasidium pullulans although growth is good upon a variety of other carbon sources. Light increases growth markedly when polysaccharides are the carbon source but not when other sugars are used. Variation in cell morphology is described in response to sugars and light. Extracellular granules, whose properties resemble those of melanin, are produced when dextrine is the carbon source in a defined medium containing asparagine as the source of nitrogen. The dark pigment was extracted from the walls of thick-walled brown cells ofA. pullulans and characterized as a melanin on the basis of several tests, including solubility and absorption spectrum.A. pullulans was grown on several defined and undefined media and the response of the fungus to light is shown to be determined by the medium, and the temperature at which the cultures are grown.     

Isolation and characterization of a novel ε-caprolactam-degrading microbe, Acinetobacter calcoaceticus, from industrial wastewater by chemostat-enrichment

For the isolation of a ε-caprolactam-degrading microbe from wastewaters of a factory producing caprolactam, we applied a chemostat-enrichment technique with a selective medium containing caprolactam as sole source of carbon and nitrogen. This allowed for the isolation of a novel caprolactam-degrading microbe, identified as Acinetobacter calcoaceticus. The strain had a critical tolerance of 19 g caprolactam l^?1 in minimal medium, which is higher than any previously reported caprolactam-degrading microbe. A. calcoaceticus also decreased the caprolactam content in medium by 65 % within 72 h despite the high caprolactam content (10 g l^?1). This study highlights the potential use of A. calcoaceticus strain for the bioremediation of recalcitrant synthetic polymers, such as caprolactam.     

Factors leading to agro-biodiversity loss in developing countries: the case of Nepal

This article is concerned with factors contributing to agro-biodiversityloss in Nepal. The aim of this paper is to analyse the causes ofagro-biodiversity loss and draw out some concrete recommendations. The fieldstudy was conducted in six districts of Nepal using qualitative researchmethods. These methods were focused group discussion, key informant interview,informal discussion, semi-structured interview and transact. The paper concludesthat commercialisation of agriculture, the weak policy and regulatory framework,increased accessibility, changes in cropping patterns and land use practices,social inequality, population growth and technological advancement are greatlycontributing to agro-biodiversity loss in Nepal. Existing Nepaleseagro-biodiversity is in serious threat if appropriate actions are not taken intime.     

Proton-activated chloride channel PAC regulates endosomal acidification and transferrin receptor-mediated endocytosis

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The voltage-gated calcium-channel β subunit: more than just an accessory

Voltage-gated Ca²⁺ channels (VGCCs) are involved in a number of excitatory processes in the cell that regulate muscle contraction, neurotransmitter release, gene regulation, and neuronal migration. They consist of a central pore-forming α₁ subunit together with a number of associated auxiliary subunits including a cytoplasmic β subunit. With the aid of X-ray crystallography, it has been found that the β subunits of VGCCs (β_2a, β₃, and β₄) interact strongly with the I–II loop of the pore-forming α₁ subunit. Here we discuss the potential interaction sites of β_1a with its α₁ subunit as well as the skeletal ryanodine receptor. We suggest that not only can β_1a interact with the α₁ subunit I–II loop, but more subtle interactions may be possible through the II–III loop via the β_1a SH3 domain. Such findings could have important implications with respect to EC coupling.     

Herbicidal influence on the uptake of phosphorus by paddy (Oryza sativa L.) and maize (Zea mays L.)

Summary Phosphorus uptake is significantly reduced in paddy and maize by the application of atrazine, DPA, EPTC and 2, 4-D from quarter normal to twice normal levels except 2 kg/ha of 2, 4-D which increased phosphorus absorption in maize. The most effective treatments are 2 kg/ha atrazine and 8 kg/ha EPTC which reduced P uptake to 55.50 and 48.12 % of control in paddy and maize respectively. Absorption of³²P by paddy and maize has also been reduced significantly by the application of above mentioned herbicides with the exception of 1 kg/ha EPTC which slightly increased it in maize.