Characterization of an OmpA-like outer membrane protein of the acidophilic iron-oxidizing bacterium, <Emphasis Type="Italic">Acidithiobacillus ferrooxidans</Emphasis>

An OmpA family protein (FopA) previously reported as one of the major outer membrane proteins of an acidophilic iron-oxidizing bacterium Acidithiobacillus ferrooxidans was characterized with emphasis on the modification by heat and the interaction with peptidoglycan. A 30-kDa band corresponding to the FopA protein was detected in outer membrane proteins extracted at 75°C or heated to 100°C for 10 min prior to sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). However, the band was not detected in outer membrane proteins extracted at ≤40°C and without boiling prior to electrophoresis. By Western blot analysis using the polyclonal antibody against the recombinant FopA, FopA was detected as bands with apparent molecular masses of 30 and 90 kDa, suggesting that FopA existed as an oligomeric form in the outer membrane of A. ferrooxidans. Although the fopA gene with a sequence encoding the signal peptide was successfully expressed in the outer membrane of Escherichia coli, the recombinant FopA existed as a monomer in the outer membrane of E. coli. FopA was detected in peptidoglycan-associated proteins from A. ferrooxidans. The recombinant FopA also showed the peptidoglycan-binding activity.     

Ecology, sexual selection and speciation

The spectacular diversity in sexually selected traits among animal taxa has inspired the hypothesis that divergent sexual selection can drive speciation. Unfortunately, speciation biologists often consider sexual selection in isolation from natural selection, even though sexually selected traits evolve in an ecological context: both preferences and traits are often subject to natural selection. Conversely, while behavioural ecologists may address ecological effects on sexual communication, they rarely measure the consequences for population divergence. Herein, we review the empirical literature addressing the mechanisms by which natural selection and sexual selection can interact during speciation. We find that convincing evidence for any of these scenarios is thin. However, the available data strongly support various diversifying effects that emerge from interactions between sexual selection and environmental heterogeneity. We suggest that evaluating the evolutionary consequences of these effects requires a better integration of behavioural, ecological and evolutionary research.     

Selective targeting of histone methylation

Histones are post-translationally modified by multiple histonemodifying enzymes, which in turn influences gene expression. Much of the work in the field to date has focused on genetic, biochemical and structural characterization of these enzymes. The most recent genome-wide methods provide insights into specific recruitment of histone-modifying enzymes in vivo and, therefore, onto mechanisms of establishing a differential expression pattern. Here we focus on the recruitment mechanisms of the enzymes involved in the placement of two contrasting histone marks, histone H3 lysine 4 (H3K4) methylation and histone H3 lysine 27 (H3K27) methylation. We describe distribution of their binding sites and show that recruitment of different histone-modifying proteins can be coordinated, opposed or alternating. Specifically, genomic sites of the H3K4 histone demethylase KDM5A become accessible to its homolog KDM5B in cells with a lowered KDM5A level. The currently available data on recruitment of H3K4/H3K27 modifying enzymes suggests that the formed protein complexes are targeted in a sequential and temporal manner, but that additional, still unknown, interactions contribute to targeting specificity.Key words: histone-modifying enzymes, histone methylation, ChIPseq     

Timing of enteral feeding in cerebral malaria in resource-poor settings: a randomized trial

Background

Early start of enteral feeding is an established treatment strategy in intubated patients in intensive care since it reduces invasive bacterial infections and length of hospital stay. There is equipoise whether early enteral feeding is also beneficial in non-intubated patients with cerebral malaria in resource poor settings. We hypothesized that the risk of aspiration pneumonia might outweigh the potential benefits of earlier recovery and prevention of hypoglycaemia.

Method and Findings

A randomized trial of early (day of admission) versus late (after 60 hours in adults or 36 hours in children) start of enteral feeding was undertaken in patients with cerebral malaria in Chittagong, Bangladesh from May 2008 to August 2009. The primary outcome measures were incidence of aspiration pneumonia, hypoglycaemia and coma recovery time. The trial was terminated after inclusion of 56 patients because of a high incidence of aspiration pneumonia in the early feeding group (9/27 (33%)), compared to the late feeding group (0/29 (0%)), p = 0.001). One patient in the late feeding group, and none in the early group, had hypoglycaemia during admission. There was no significant difference in overall mortality (9/27 (33%) vs 6/29 (21%), p = 0.370), but mortality was 5/9 (56%) in patients with aspiration pneumonia.

Conclusions

In conclusion, early start of enteral feeding is detrimental in non-intubated patients with cerebral malaria in many resource-poor settings. Evidence gathered in resource rich settings is not necessarily transferable to resource-poor settings.

Trial Registration

Controlled-Trials.com ISRCTN57488577     

An annotated checklist of the orchids of Nepal

An annotated checklist comprised of 458 taxa of orchids known from Nepal is provided, including 104 genera, 437 species, 16 varieties, 3 subspecies and 2 forma and 18 endemic species. In Nepal, orchid species are distributed from 60–5200 m a.s.l. In the checklist, notes on altitudinal ranges, habit, habitat, global distribution, phenology, etc. are presented.     

Antifungal activity of a Pinus monticola antimicrobial peptide 1 (Pm-AMP1) and its accumulation in western white pine infected with Cronartium ribicola

Pinus monticola antimicrobial peptide 1 (Pm-AMP1) was expressed and purified from bacterial cell lysate and its identity and purity confirmed by Western blot analysis using the Pm-AMP1 antibody. Application of Pm-AMP1 resulted in visible hyphal growth inhibition of Cronartium ribicola , Phellinus sulphurascens , Ophiostoma montium , and Ophiostoma clavigerum 3-12 days post-treatment. Pm-AMP1 also inhibited spore germination of several other phytopathogenic fungi by 32%-84% 5?days post-treatment. Microscopic examination of C. ribicola hyphae in contact with Pm-AMP1 showed distinct morphological changes. Seven western white pine ( Pinus monticola Douglas ex D. Don) families (Nos. 1, 2, 5, 6, 7, 8, 10) showing partial resistance to C.?ribicola in the form of bark reaction (BR) were assessed by Western immunoblot for associations between Pm-AMP1 accumulation and family, phenotype, canker number, and virulence of C. ribicola. There was a significant difference (p?< 0.001) in mean Pm-AMP1 protein accumulation between families, with higher levels detected in the full-sib BR families (Nos. 1, 2, 5) than the half-sib BR families (Nos. 6, 7). Family 8, previously described as a Mechanism 'X' BR family, had the highest number of BR seedlings and displayed high Pm-AMP1 levels, whereas the susceptible family (No. 10) showed the lowest levels (p?< 0.05). Family 1 showed a significant association between Pm-AMP1 accumulation and overall seedling health (p?< 0.01, R?= 0.533), with higher protein levels observed in healthy versus severely infected seedlings. In general, low Pm-AMP1 levels were observed with an increase in the number of cankers per seedling (p?< 0.05), and seedlings inoculated with the avirulent source of C. ribicola showed significantly higher Pm-AMP1 levels (p?< 0.05) in the majority of BR families. Cis-acting regulatory elements, such as CCAAT binding factors, and an AG-motif binding protein were identified in the Pm-AMP1 promoter region. Multiple polymorphic sites were identified within the 5' untranslated region and promoter regions. Our results suggest that Pm-AMP1 is involved in the western white pine defense response to fungal infection, as observed by its antifungal activity on C. ribicola and a range of phytopathogens as well as through its association with different indicators of resistance to C.?ribicola.     

Notch activation augments nitric oxide/soluble guanylyl cyclase signaling in immortalized ovarian surface epithelial cells and ovarian cancer cells

Nitric oxide (NO) is generated by tumor, stromal and endothelial cells and plays a multifaceted role in tumor biology. Many physiological functions of NO are mediated by soluble guanylyl cyclase (sGC) and NO/sGC signaling has been shown to promote proliferation and survival of ovarian cancer cells. However, how NO/sGC signaling is modulated in ovarian cancer cells has not been studied. The evolutionarily conserved Notch signaling pathway plays an oncogenic role in ovarian cancer. Here, we report that all three ovarian cancer cell lines we examined express a higher level of GUCY1B3 (the β subunit of sGC) compared to non-cancerous immortalized ovarian surface epithelial (IOSE) cell lines. Interestingly, the highest expression of GUCY1B3 in ovarian cancer OVCAR3 cells is concurrent with the expression of Notch3. In IOSE cells, forced activation of Notch3 increases the expression of GUCY1B3, NO-induced cGMP production, and the expression of cGMP-dependent protein kinase (PKG), thereby enhancing NO- and cGMP-induced phosphorylation of vasodilator-stimulated phosphoprotein (VASP, a direct PKG substrate protein). In contrast, inhibition of Notch by DAPT reduces GUCY1B3 expression and NO-induced cGMP production and VASP phosphorylation in OVCAR3 cells. Finally, we confirmed that inhibition of sGC by ODQ decreases growth of ovarian cancer cells. Together, our work demonstrates that Notch is a positive regulator of NO/sGC signaling in IOSE and ovarian cancer cells, providing the first evidence that Notch and NO signaling pathways interact in IOSE and ovarian cancer cells.     

Deciphering the interaction of food additive,vanillin with DNA: A biophysical and computational study

Communicated by Ramaswamy H. Sarma     

Synergistic effect of cytokinin and gibberellins stimulates release of dormancy in tea ( Camellia sinensis ( L.) O. Kuntze) bud

Reactivation of dormant meristem in banjhi (dormant) shoots is important to enhance the quality and quantity of tea production. The field grown tea bushes were subjected to treatment with dormancy breaking agents such as potassium nitrate (KNO3), thiourea, sodium nitro prusside (SNP), the phytohormones kinetin (Kn) and gibberellins (GA). The efficacy of Kn and GA were comparatively lesser than KNO3 while the combination of Kn and GA (50 and100 ppm respectively) resulted in better dormancy reduction in tea buds. This observation was supported by our results from gene expression study where accumulation patterns of mRNAs corresponding to histones (H2A, H2B, H3 and H4), cyclins (B2, D1 and D3), cyclin-dependent kinase (CDKA), ubiquitination enzymes (FUS, EXT CE2), cyclophilin, E2F, and tubulin were analyzed during growth-dormancy cycles in tea apical buds under the influence of Kn, GA and their combinations. The level of these mRNAs was low in dormant buds, which was significantly increased by foliar application of GA and Kn combination. The present study indicated that the foliar application of GA in combination with Kn will help to improve quality and quantity of tea production by breaking dormancy and stimulating the bud growth.