DNA strand scission by neocarzinostatin: molecular recognition process responsible for site-specificity

A series of hexanucleotides possessing A-T, G-C, inosine (I)-C and 2-aminoadenine (ANH2)-T base pairs at 5'-side of the target thymine were prepared and their selectivity for C-5' and C4' oxidation in the NCS-mediated degradation was investigated. Quantitative product analysis indicated that preferential C5' oxidation of deoxyribose moiety of the target T occurs at -5'-AT- and 5'-IT- sites, whereas C5' and C4' oxidation occurs competitively at T of -5'-GT- and -5'-ANH2T- sites. Based on the experimental results, an intercalation model that permits competitive hydrogen abstraction from C5' and C4' of deoxyribose moiety has been proposed.     

Oxygen concentration-dependent induction of a 140-kDa protein in magnetic bacterium Magnetospirillum magnetotacticum MS-1

Abstract The magnetic bacterium Magnetospirillum magnetotacticum prefers a microaerobic habitat and should be able to sense oxygen. Therefore, the bacterium was cultured under atmospheres containing 0–5% O₂ and analyzed for oxygen-dependent changes in the levels of its protein components by sodium dodecyl sulfate-polyccrylamide gel electrophoresis (SDS-PAGE). The analysis revealed a marked anaerobic induction of a 140-kDa protein, which was suppressed when M. magnetotacticum was switched from microaerobic (<1% O₂) to aerobic (>1% O₂) growth conditions. Although its function remains to be determined, the 140-kDa protein may serve as a useful tool to gain insight into the physiology of the organism.     

The transition in frequency of Y chromatin in males during the neonatal period

Summary The frequency of Y chromatin, visualized as fluorescent bodies in cell nuclei from lymphocytes in blood smears, was signficantly less in newborn males than in three-month-old male infants and adults. The frequency of Y chromatin-positive cells on day 0 was 36.16±9.11% and then increased daily. At one month after birth the frequency was 55.07±9.29%, which was not significantly different from that in adult males (57.08±5.97%).     

Analysis of the effects of snake venom proteinases on the activity of human plasma C1 esterase inhibitor, alpha 1-antichymotrypsin and alpha 2-antiplasmin

Incubation of C1 esterase inhibitor with Crotalid, Viperid and Colubrid snake venoms resulted in enzymatic inactivation of the inhibitor. Intact inhibitor (104 kDa) was converted into an active intermediate species of 89 kDa and then a further cleavage resulted in formation of an 86-kDa inactive inhibitor. In contrast, C1 esterase inhibitor did not lose activity during incubation with Elapid venoms; however, the intact inhibitor was gradually converted to an active species of 89 kDa during the incubation. Human alpha 1-antichymotrypsin was inactivated by all venoms tested, including those from the Elapid family. The 67-kDa intact inhibitor was converted by the venom proteinases to an inactive 63-kDa form. The results suggest that this acute-phase plasma protein is readily susceptible to inactivation by venom proteinases. Human alpha 2-antiplasmin (68 kDa) was cleaved to form a 61-kDa active intermediate, which then underwent a second cleavage to produce an inactive 53-kDa product. Elapid venoms had no effect on alpha 2-antiplasmin activity and did not cleave this inhibitor. All inhibitors were inactivated with catalytic amounts of venom proteinases. No stable proteinase-proteinase inhibitor complexes were detected, and no random proteolysis of the inhibitors occurred.     

Impact of Noncovalent Sulfur–Fluorine Interaction Position on Properties,Structures, and Photovoltaic Performance in Naphthobisthiadiazole‐Based Semiconducting Polymers

Controlling the energetics and backbone order of semiconducting polymers is essential for the performance improvement of polymer‐based solar cells. The use of fluorine as the substituent for the backbone is known to effectively deepen the molecular orbital energy levels and coplanarize the backbone by noncovalent interactions with sulfur of the thiophene ring. In this work, novel semiconducting polymers are designed and synthesized based on difluoronaphthobisthiadiazole (FNTz) as a new family of naphthobisthiadiazole (NTz)–quaterthiophene copolymer systems, which are one of the highest performing polymers in solar cells. The effect of the fluorination position on the energetics and backbone order is systematically studied. It is found that the dependence of the solar cell fill factor on the active layer thickness is very sensitive to the fluorination position. It is thus further investigated and discussed how the structural features of the polymers influence the photovoltaic parameters as well as the diode characteristics and bimolecular recombination. Further, the polymer with fluorine on both the naphthobisthiadiazole and quaterthiophene moieties exhibits a quite high power conversion efficiency of 10.8% in solar cells in combination with a fullerene. It is believed that the results would offer new insights into the development of semiconducting polymers.     

Association of Allergic Symptoms with Dengue Infection and Severity: A Systematic Review and Meta-analysis

The relationship between the severity of dengue infection and allergy is still obscure. We conducted an electronic search across 12 databases for relevant articles reporting allergic symptoms, dengue infection, and dengue classification. These studies were categorized according to dengue severity and allergy symptoms, and a meta-analysis was performed by pooling the studies in each category. Among the included 57 articles, pruritus was the most common allergic sign followed by non-specified allergy and asthma(28.6%, 13%, and 6.5%, respectively). Despite the reported significant association of dengue with pruritus and total Ig E level(P \ 0.05), in comparison with non-dengue cases and healthy controls, there was no association between the different severe dengue group with pruritus, skin allergy, food allergy or asthma. However,removing the largest study revealed a significant association between asthma with dengue hemorrhagic fever(DHF) rather than dengue fever(DF). In comparison with DF, DHF was associated with Ig E positivity. Furthermore, specific-Ig E level was higher in secondary DF rather than primary DF. There was a possible association between allergy symptoms and dengue severity progression. Further studies are needed to clarify this association.     

Glycine significantly enhances bacterial membrane vesicle production: a powerful approach for isolation of LPS-reduced membrane vesicles of probiotic Escherichia coli

Bacterial membrane vesicles (MVs) have attracted strong interest in recent years as novel nanoparticle delivery platforms. Glycine is known to induce morphological changes in the outer layer of bacteria. We report here that glycine dramatically facilitates MV production in a flagella-deficient mutant of the non-pathogenic probiotic Escherichia coli strain Nissle 1917. Supplementation of culture medium with 1.0% glycine induced cell deformation at the early exponential phase, eventually followed by quasi-lysis during the late exponential to stationary phase. Glycine supplementation also significantly increased the number of MVs with enlarged particle size and altered the protein profile with an increase in the inner membrane and cytoplasmic protein contents as compared to non-induced MVs. Of note, the endotoxin activity of glycine-induced MVs was approximately eightfold or sixfold lower than that of non-induced MVs when compared at equal protein or lipid concentrations respectively. Nevertheless, glycine-induced MVs efficiently induced both immune responses in a mouse macrophage-like cell line and adjuvanticity in an intranasal vaccine mouse model, comparable to those of non-induced MVs. We propose that the present method of inducing MV production with glycine can be used for emerging biotechnological applications of MVs that have immunomodulatory activities, while dramatically reducing the presence of endotoxins.     

Correction to: Molecular mechanisms mediating root hydrotropism: what we have observed since the rediscovery of hydrotropism

Journal of Plant Research - The article Molecular mechanisms mediating root hydrotropism