Hexavalent chromate reduction by immobilized Streptomyces griseus

Hexavalent chromium, which is a mutagen and carcinogen, was efficiently reduced by Streptomyces griseus. This activity was associated with the cell. Cr⁶⁺ reduction by free as well as immobilized cells was studied: cells in PVA-alginate had the highest (100%) Cr⁶⁺ removal efficiency in 24 h with reduction rates similar to free cells. Immobilized cells completely reduced 25 mg Cr⁶⁺ l⁻¹ in 24 h. PVA-alginate immobilized cells could be reused four times to completely reduce 25 mg Cr⁶⁺ l⁻¹ in 24 h each time. Chromate in a simulated effluent containing Cu²⁺, Mg²⁺, Mn²⁺ and Zn²⁺ was completely reduced by PVA-alginate immobilized cells within 9 h.     

Fluorescence‐based sensor for selective and sensitive detection of amoxicillin (Amox) in aqueous medium: Application to pharmaceutical and biomedical analysis

We here for the first time demonstrate an analytical approach for the highly selective and sensitive detection of amoxicillin (Amox) in aqueous medium based on the fluorescence quenching of quantum dots (QDs). The change in fluorescence intensity of mercaptopropionic acid‐capped cadmium sulphide (MPA‐CdS) QDs is attributed to the increasing concentration of Amox. The results show that the fluorescence quenching of QDs by Amox takes place through both static and dynamic types of quenching mechanism. The fluorescence quenching of QDs with increase in concentration of Amox shows the linear range between 5 μg ml^?1 and 30 μg ml^?1 and the limit of detection (LOD) is 5.19 μg ml^?1. There is no interference of excipients, which are commonly present in pharmaceutical formulation and urine samples. For the practical application approach, the developed method has been successfully applied for the determination of Amox in pharmaceutical formulations and urine samples with acceptable results.     

Hydroxylation of progesterone by Cunninghamella blakesleeana NCIM 687

Progesterone was completely hydroxylated, principally to 11,14 dihydroxyprogesterone by Cunninghamella blakesleeana NCIM 687 in 48h.S.B. Chincholkar is with the Microbiology Division, Department of Life Sciences, North Maharashtra University, Jalgaon 425 001, India. R. Seeta Laxman is with the Division of Biochemical Sciences, National Chemical Laboratory, Pune 411 008, India. R.D. Wakharkar is with Organic Chemistry. Technology Division, National Chemical Laboratory, Pune 411 008. India     

The Cytoplasmic Zinc Finger Protein ZPR1 Accumulates in the Nucleolus of Proliferating Cells

The zinc finger protein ZPR1 translocates from the cytoplasm to the nucleus after treatment of cells with mitogens. The function of nuclear ZPR1 has not been defined. Here we demonstrate that ZPR1 accumulates in the nucleolus of proliferating cells. The role of ZPR1 was examined using a gene disruption strategy. Cells lacking ZPR1 are not viable. Biochemical analysis demonstrated that the loss of ZPR1 caused disruption of nucleolar function, including preribosomal RNA expression. These data establish ZPR1 as an essential protein that is required for normal nucleolar function in proliferating cells.     

Use of azidobestatin as a photoaffinity label to identify the active site peptide of leucine aminopeptidase.

Aminopeptidases catalyze the hydrolysis of amino acid residues from the amino terminus of peptide substrates. They are found in most cells and tissues, and their activity has been implicated in myriad fundamental biochemical and physiological processes. Nevertheless, little is known about the structure of the aminopeptidase active sites. Beef lens leucine aminopeptidase (blLAP) can be considered prototypical of many enzymes in this family of peptidases. Bestatin, [(2S,3R)-(3-amino-2-hydroxy-4-phenyl-butanoyl)-L-leucine] is a nonhydrolyzable substrate analogue of a peptide, PheLeu, which is rapidly cleaved by blLAP. Bestatin incorporates elements of the putative tetrahedral intermediate, and this results in a greater than 10(5)-fold enhancement of binding relative to analogous peptides. Bestatin is the most tightly bound inhibitor of many aminopeptidases. Bestatin was successively converted to nitrobestatin, p-aminobestatin, [3H]-p-aminobestatin, and finally [3H]-p-azidobestatin (pAB). Like bestatin, pAB is a slow binding inhibitor of LAP (Ki*, the dissociation constant for the final complex, = approximately 4 x 10(-9); Ki, the dissociation constant for the initial collision complex, = approximately 10(-8). The t1/2 for binding of 2 x 10(-8) M and 8 x 10(-8) M bestatin are approximately 60 min and approximately 38 min, respectively. pAB, nitrobestatin, bestatin, and physiological peptides appear to bind in the same site, the first three with similar avidity. In the dark, pAB and bestatin protect low concentrations of the enzyme against inactivation upon extensive dialysis. The t1/2 for photoactivation of pAB is approximately 3 s. Irradiation of blLAP for such short periods of time resulted in insignificant change in activity. blLAP which was placed in 254-nm light in the presence of pAB was inactivated significantly. Treatment of photolabeled blLAP with trypsin produces only two peptides. Autoradiography and scintillation counting indicate that the active site is in the peptide which includes residues 138-487. Treatment of the same blLAP with hydroxylamine produces two different peptides, with the active site in the peptide 323-487. This indicates that the active site is in the carboxyl-terminal one-third of the protomer. It is likely that this photoaffinity label will be useful in identifying active sites in other aminopeptidases as well.     

Multiple e-pharmacophore modelling pooled with high-throughput virtual screening,docking and molecular dynamics simulations to discover potential inhibitors of Plasmodium falciparum lactate dehydrogenase (PfLDH)

Development of new antimalarial drugs continues to be of huge importance because of the resistance of malarial parasite towards currently used drugs. Due to the reliance of parasite on glycolysis for energy generation, glycolytic enzymes have played important role as potential targets for the development of new drugs. Plasmodium falciparum lactate dehydrogenase (PfLDH) is a key enzyme for energy generation of malarial parasites and is considered to be a potential antimalarial target. Presently, there are nearly 15 crystal structures bound with inhibitors and substrate that are available in the protein data bank (PDB). In the present work, we attempted to consider multiple crystal structures with bound inhibitors showing affinity in the range of 1.4 × 10²–1.3 × 10⁶ nM efficacy and optimized the pharmacophore based on the energy involved in binding termed as e-pharmacophore mapping. A high throughput virtual screening (HTVS) combined with molecular docking, ADME predictions and molecular dynamics simulation led to the identification of 20 potential compounds which could be further developed as novel inhibitors for PfLDH.     

Phylogeographical analysis shows the need to protect the wild yaks' last refuge in Nepal

The wild yak Bos mutus was believed to be regionally extinct in Nepal for decades until our team documented two individuals from Upper Humla, north‐western Nepal, in 2014. The International Union for Conservation of Nature (IUCN) seeks further evidence for the conclusive confirmation of that sighting. We conducted line transects and opportunistic sign surveys in the potential wild yak habitats of Humla, Dolpa, and Mustang districts between 2015 and 2017 and collected genetic samples (present and historic) of wild and domestic yaks Bos grunniens. We also sighted another wild yak in Upper Humla in 2015. Phylogenetic and haplotype network analyses based on mitochondrial D‐loop sequences (~450 bp) revealed that wild yaks in Humla share the haplotype with wild yaks from the north‐western region of the Qinghai‐Tibetan Plateau in China. While hybridization with domestic yaks is a major long‐term threat, illegal hunting for meat and trophy put the very small populations of wild yaks in Nepal at risk. Our study indicates that the unprotected habitat of Upper Humla is the last refuge for wild yaks in Nepal. We recommend wild yak conservation efforts in the country to focus on Upper Humla by (i) assigning a formal status of protected area to the region, (ii) raising awareness in the local communities for wild yak conservation, and (iii) providing support for adaptation of herding practice and pastureland use to ensure the viability of the population.     

Evidence for a radial strain gradient in apple fruit cuticles

Main conclusion

The morphological outer side of the apple fruit cuticle is markedly more strained than the inner side. This strain is released upon wax extraction. This paper investigates the effect of ablating outer and inner surfaces of isolated cuticular membranes (CM) of mature apple (Malus × domestica) fruit using cold atmospheric pressure plasma (CAPP) on the release of strain after extraction of waxes. Strain release was quantified as the decrease in area of CM discs following CAPP treatment and subsequent solvent extraction of wax. Increasing duration of CAPP treatment proportionally decreased CM mass per unit area. There was no difference in mass loss rate between CAPP treatments of outer or inner surfaces. Also, there was no difference in surface area of CMs before and after CAPP treatment. However, upon subsequent wax extraction, surface area of CMs decreased indicating the release of strain. Increasing the duration of CAPP treatment resulted in increasing strain release up to 47.7 ± 8.0 % at 20 min when CAPP was applied to the inner surface. In contrast, strain release was independent of CAPP duration averaging about 12.1 ± 0.6 % when applied to the outer surface of the CM. Our results provide evidence for a marked gradient of strain between the outer side (strained) and the inner side of the CM (not strained) of mature apple fruit.     

Molecular Mechanisms of Hypoxic Responses via Unique Roles of Ras1, Cdc24 and Ptp3 in a Human Fungal Pathogen Cryptococcus neoformans

Cryptococcus neoformans encounters a low oxygen environment when it enters the human host. Here, we show that the conserved Ras1 (a small GTPase) and Cdc24 (the guanine nucleotide exchange factor for Cdc42) play an essential role in cryptococcal growth in hypoxia. Suppressor studies indicate that PTP3 functions epistatically downstream of both RAS1 and CDC24 in regulating hypoxic growth. Ptp3 shares sequence similarity to the family of phosphotyrosine-specific protein phosphatases and the ptp3Δ strain failed to grow in 1% O₂. We demonstrate that RAS1, CDC24 and PTP3 function in parallel to regulate thermal tolerance but RAS1 and CDC24 function linearly in regulating hypoxic growth while CDC24 and PTP3 reside in compensatory pathways. The ras1Δ and cdc24Δ strains ceased to grow at 1% O₂ and became enlarged but viable single cells. Actin polarization in these cells, however, was normal for up to eight hours after transferring to hypoxic conditions. Double deletions of the genes encoding Rho GTPase Cdc42 and Cdc420, but not of the genes encoding Rac1 and Rac2, caused a slight growth retardation in hypoxia. Furthermore, growth in hypoxia was not affected by the deletion of several central genes functioning in the pathways of cAMP, Hog1, or the two-component like phosphorylation system that are critical in the cryptococcal response to osmotic and genotoxic stresses. Interestingly, although deletion of HOG1 rescued the hypoxic growth defect of ras1Δ, cdc24Δ, and ptp3Δ, Hog1 was not hyperphosphorylated in these three mutants in hypoxic conditions. RNA sequencing analysis indicated that RAS1, CDC24 and PTP3 acted upon the expression of genes involved in ergosterol biosynthesis, chromosome organization, RNA processing and protein translation. Moreover, growth of the wild-type strain under low oxygen conditions was affected by sub-inhibitory concentrations of the compounds that inhibit these biological processes, demonstrating the importance of these biological processes in the cryptococcal hypoxia response.