Effect of visible light on catalytic hydrolysis of p-nitrophenyl palmitate by the Pseudomonas cepacia lipase immobilized on sol–gel support

This paper demonstrates Pseudomonas cepacia lipase catalyzed hydrolysis of p-nitrophenyl palmitate under irradiation of light with wavelengths of 250–750 nm. The reaction follows Michaelis–Menten Kinetics and the light irradiation increases the overall rate of hydrolysis. Using Lineweaver–Burk plot K _M and V _max values for the reaction in presence of light are found to be 39.07 and 66.67 mM/min/g, respectively; while for the same reaction under dark condition, the values are 7.08 and 10.21 mM/min/g. The linear form of enzyme dependent rate of reaction confirms that no mass-transfer limitations are present and the reaction is a kinetically controlled enzymatic reaction.     

BayMeth: improved DNA methylation quantification for affinity capture sequencing data using a flexible Bayesian approach

Affinity capture of DNA methylation combined with high-throughput sequencing strikes a good balance between the high cost of whole genome bisulfite sequencing and the low coverage of methylation arrays. We present BayMeth, an empirical Bayes approach that uses a fully methylated control sample to transform observed read counts into regional methylation levels. In our model, inefficient capture can readily be distinguished from low methylation levels. BayMeth improves on existing methods, allows explicit modeling of copy number variation, and offers computationally efficient analytical mean and variance estimators. BayMeth is available in the Repitools Bioconductor package.     

Genetically engineered production of 1,1′-bis-valienamine and validienamycin in <Emphasis Type="Italic">Streptomyces hygroscopicus</Emphasis> and their conversion to valienamine

The antifungal agent validamycin A is an important crop protectant and the source of valienamine, the precursor of the antidiabetic drug voglibose. Inactivation of the valN gene in the validamycin A producer, Streptomyces hygroscopicus subsp. jinggangensis 5008, resulted in a mutant strain that produces new secondary metabolites 1,1′-bis-valienamine and validienamycin. The chemical structures of 1,1′-bis-valienamine and validienamycin were elucidated by 1D and 2D nuclear magnetic resonance (NMR) spectroscopy in conjunction with mass spectrometry and bioconversion employing a glycosyltransferase enzyme, ValG. 1,1′-Bis-valienamine and validienamycin exhibit a moderate antifungal activity against Pellicularia sasakii. Chemical degradation of 1,1′-bis-valienamine using N-bromosuccinimide followed by purification of the products with ion-exchange column chromatography only resulted in valienamine, whereas parallel treatments of validoxylamine A, the aglycon of validamycin A, resulted in an approximately 1:1 mixture of valienamine and validamine, underscoring the advantage of 1,1′-bis-valienamine over validoxylamine A as a commercial source of valienamine. Hui Xu and Jongtae Yang contributed equally to this paper.     

Sphingomyelinase dependent apoptosis following treatment of pancreatic beta-cells with amyloid peptides Aß1-42 or IAPP

Amyloid peptides interfere with survival of pancreatic beta-cells. In some cells apoptosis is paralleled by ceramide-dependent alterations of ion channel activity. The purpose of the present study was to elucidate the dependence of amyloid peptides Aß_1-42 and islet amyloid polypeptide (IAPP)-induced cell death on ceramide formation and ion channel activity in murine pancreatic islet cells. As disclosed by TUNEL (terminal dUTP nick-end labelling) and cleaved caspase 3 staining, apoptotic cell death was induced by Aß_1-42, IAPP and exogenously added C2-ceramide in islet cells from wild type mice. In islet cells from acid sphingomyelinase-deficient mice (ASMKO) Aß_1-42 and IAPP but not exogenously added N-acetyl-d-sphingosine (C2-ceramide, 20 μM) failed to stimulate apoptosis. Immunofluorescent staining revealed a stimulatory effect of Aß_1-42 on ceramide formation. According to patch clamp experiments, administration of Aß_1-42 and IAPP significantly decreased outwardly rectifying whole cell currents in wild type but not in ASMKO islet cells. C2-ceramide but not inactive di-ceramide (20 μM) mimicked the inhibitory effect on Kv channel current. In conclusion, amyloid peptides induce apoptosis of pancreatic islet cells at least in part through activation of acid sphingomyelinase resulting in production of ceramide and subsequent inhibition of ion channel activity.     

The Plk1 inhibitor BI 2536 temporarily arrests primary cardiac fibroblasts in mitosis and generates aneuploidy in vitro

BI 2536 is a new anti-mitotic drug that targets polo-like kinase 1 (Plk1) and is currently under clinical development for cancer therapy. The effect of this drug on cancer cells has been extensively investigated, but information about the effects on primary dividing cells and differentiated non-dividing cells is scarce. We have investigated the effects of this drug on primary neonatal rat cardiac fibroblasts and on differentiated cardiomyocytes and explored the possibility to use this drug to enrich differentiated cell populations in vitro. BI 2536 had a profound effect on cardiac fibroblast proliferation in vitro and arrested these cells in mitosis with an IC50 of about 43 nM. Similar results were observed with primary human cells (HUVEC, IC50 = 30 nM), whereas the cancer cell line HeLa was more sensitive (IC50 of 9 nM). Further analysis revealed that prolonged mitotic arrest resulted in cell death for about 40% of cardiac fibroblasts. The remaining cells showed an interphase morphology with mostly multi- and micro-nucleated nuclei. This indicates that a significant number of primary fibroblasts are able to escape BI 2536 induced mitotic arrest and apparently become aneuploid. No effects were observed on cardiomyocytes and hypertrophic response (growth) upon endothelin-1 and phenylephrine stimulation was normal in the presence of BI 2536. This indicates that BI 2536 has no adverse effects on terminally differentiated cells and still allows proliferation independent growth induction in these cells. In conclusion, cardiomyocytes could be enriched using BI 2536, but the formation of aneuploidy in proliferating cells most likely limits this in vitro application and does not allow its use in putative cell based therapies.     

Optimization of 2-aminothiazole derivatives as CCR4 antagonists

A series of 2-aminothiazole-derived antagonists of the CCR4 receptor has been synthesized and their affinity for the receptor evaluated using a [(125)I]TARC (CCL17) displacement assay. Optimization of these compounds for potency and pharmacokinetic properties led to the discovery of potent, orally bioavailable antagonists.     

Tyrosinase inhibition studies of cycloartane and cucurbitane glycosides and their structure-activity relationships

In the present paper, tyrosinase inhibition studies and structure-activity relationship of eight cycloartane glycosides and one cucurbitane glycoside and its genin, which were isolated from Astragalus (Leguminoseae) and Bryonia (Cucurbitaceae) plants, have been discussed. The activities are compared with two reference tyrosinase inhibitors, kojic acid and l-mimosine. These studies and the SAR showed that the askendoside B which exhibited highly potent (IC50 =13.95 microM) tyrosinase inhibition could be a possible lead molecule for the development of new medications of several skin diseases related with the over-expression of the enzyme tyrosinase, like hyperpigmentation. The molecule also may be interesting for the cosmetic industries as a skin whitening agent.     

Influence of Catastrophic Climatic Events and Human Waste on Vibrio Distribution in the Karnaphuli Estuary, Bangladesh

Vibrios are bacteria of marine and estuarine origin that can cause human diseases, such as cholera, and also affect aquatic organisms. The impact of storm-driven changes in salinity and suspended particulate matter (SPM) on cultivable Vibrio counts (CVC) and distribution in Karnaphuli estuary, Bangladesh, was compared before and after a strong cyclone in mid May 2007 and after a monsoon landslide a month later. CVC were higher (~10³ colony forming units—cfu/ml) at estuary’s mouth (salinity 20–15 parts per thousand, ppt) and steeply declined landwards. CVC and their proportion of total aerobic bacteria were highest after the cyclone and also increased after the landslide, likely due to higher SPM loads. The cyclone did not significantly change previous fecal coliform abundance, contrasting with the ten times increase after the landslide. Sewage input enhanced CVC near the point sources. CVC and salinity correlated highly significantly at salinities <10 ppt; however, at higher values dispersion increased, probably due to the effect of sediment resuspension on CVC. Cyclone or heavy rainfall-mediated turbidity changes jointly with salinity gradients can significantly influence abundance and distribution of estuarine vibrios. Extended salt intrusion and higher turbidities in tropical estuaries by stronger and more frequent storms and deforestation-derived erosion could favor Vibrio growth, with increasing risks for aquatic resources and human health in the coastal zone.     

Spatially and Spectrally Resolved Absorptivity: New Approach for Degradation Studies in Perovskite and Perovskite/Silicon Tandem Solar Cells

Instability in perovskite solar cells is the main challenge for the commercialization of this solar technology. Here, a contactless, nondestructive approach is reported to study degradation across perovskite and perovskite/silicon tandem solar cells. The technique employs spectrally and spatially resolved absorptivity at sub‐bandgap wavelengths of perovskite materials, extracted from their luminescence spectra. Parasitic absorption in other layers, carrier diffusion, and photon smearing phenomena are all demonstrated to have negligible effects on the extracted absorptivity. The absorptivity is demonstrated to reflect real degradation in the perovskite film and is much more robust and sensitive than its luminescence spectral peak position, representing its optical bandgap, and intensity. The technique is applied to study various common factors which induce and accelerate degradation in perovskite solar cells including air and heat exposure and light soaking. Finally, the technique is employed to extract the individual absorptivity component from the perovskite layer in a monolithic perovskite/silicon tandem structure. The results demonstrate the value of this approach for monitoring degradation mechanisms in perovskite and perovskite/silicon tandem cells at early stages of degradation and various fabrication stages.     

Cellular Expression and Subcellular Localization of Wwox Protein During Testicular Development and Spermatogenesis in Rats

A well-known putative tumor suppressor WW domain–containing oxidoreductase (Wwox) is highly expressed in hormonally regulated tissues and is considered important for the normal development and function of reproductive organs. In this study, we investigated the cellular and subcellular localization of Wwox in normal testes during postnatal days 0–70 using Western blotting and immunohistochemistry. Wwox is expressed in testes at all ages. Immunohistochemistry showed that fetal-type and adult-type Leydig cells, immature and mature Sertoli cells, and germ cells (from gonocytes to step 17 spermatids) expressed Wwox except peritubular myoid cells, step 18–19 spermatids, and mature sperm. Wwox localized diffusely in the cytoplasm with focal intense signals in all testicular cells. These signals gradually condensed in germ cells with their differentiation and colocalized with giantin for cis-Golgi marker and partially with golgin-97 for trans-Golgi marker. Biochemically, Wwox was detected in isolated Golgi-enriched fractions. But Wwox was undetectable in the nucleus. This subcellular localization pattern of Wwox was also confirmed in single-cell suspension. These findings indicate that Wwox is functional in most cell types of testis and might locate into Golgi apparatus via interaction with Golgi proteins. These unique localizations might be related to the function of Wwox in testicular development and spermatogenesis: