Weak but uniform enrichment of the histone variant macroH2A1 along the inactive X chromosome

We studied the enrichment and distribution of the histone variant mH2A1 in the condensed inactive X (Xi) chromosome. By using highly specific antibodies against mH2A1 and stable HEK 293 cell lines expressing either green fluorescent protein (GFP)-mH2A1 or GFP-H2A, we found that the Xi chromosome contains ~1.5-fold more mH2A1 than the autosomes. To determine the in vivo distribution of mH2A1 along the X chromosome, we used a native chromatin immunoprecipitation-on-chip technique. DNA isolated from mH2A1-immunoprecipitated nucleosomes from either male or female mouse liver were hybridized to tiling microarrays covering 5 kb around most promoters or the entire X chromosome. The data show that mH2A1 is uniformly distributed across the entire Xi chromosome. Interestingly, a stronger mH2A1 enrichment along the pseudoautosomal X chromosome region was observed in both sexes. Our results indicate a potential role for macroH2A in large-scale chromosome structure and genome stability.     

Sequential utilization of substrates by Pseudomonas putida CSV86: signatures of intermediate metabolites and online measurements

Pseudomonas putida CSV86 preferentially utilizes aromatics over glucose and co-metabolizes them with organic acids. On aromatics plus glucose, CSV86 utilized aromatics first with concomitant appearance of transient metabolites such as salicylate, benzaldehyde and benzoate. Citrate was the main extracellular metabolite observed during glucose uptake. The strain showed simultaneous utilization of organic acids and aromatic compounds. Based on the metabolite analysis and growth profiles, we hypothesize that the repression of glucose utilization could be due to organic acid intermediates generated from aromatic compound metabolism. The online measurements indicate the instantaneous metabolic state of the culture. For example, the CO₂ evolution and agitation speed show peak values during the two growth phases in the diauxic growth while dissolved oxygen values show decrease at the corresponding durations. These measurements correlated well with the offline measurements but provided a better time resolution of the process.     

Altered glucose homeostasis in response to aluminium phosphide induced cellular oxygen deficit in rat

The present study was designed to analyze the effect of acute aluminium phosphide (ALP) (10 mg/kg body wt.) exposure on the glucose homeostasis in rat liver and brain. ALP has been implicated in the inhibition of cytochrome oxidase causing reduced oxygen uptake and decreased ATP synthesis eventually resulting in cellular energy crisis. A significant decrease in plasma glucose levels in the ALP treated rats has been observed. Therefore, decreased ATP levels coupled with hypoglycemia may further intensify the cellular energy deficits. In order to meet the sudden increase in the local energy demand, the brain tissue utilizes its stored energy in the form of glycogen breakdown as observed by a decrease in the glycogen levels in both liver and brain which was accompanied by a marked increase in the activity of glycogen phosphorylase in both the tissues. The glycolytic rate was found to be enhanced in brain tissue as evident by increased activities of hexokinase and phosphofructokinase enzymes, but decreased in liver of ALP treated rats. Lactate levels were increased in plasma and brain, but decreased in liver of ALP treated rats. Pyruvate levels increased in the plasma and liver, but no change was observed in the brain tissue. ALP did not cause any change in the gluconeogenic enzymes like glucose-6-phosphatase and fructose-1,6-bisphophatase in brain, but a significant increase was observed in the liver. Results of the study showed that ALP induced cellular energy deficit leads to compromised energy status of liver and brain coupled with substantial alterations in glucose homeostasis. However, the activity of glucose-6-phosphate dehydrogenase decreased significantly in both the tissues.     

Synthesis and characterization of a stable paramagnetic hexacoordinated oxochromium(IV) complex with dianionic tetradentate Schiff base ligand salen

A paramagnetic octahedral oxochromium(IV) complex with dianionic tetradentate ligand salen (where H₂salen is N,N′-bis(salicylidene)-1,2-ethylenediamine) has been synthesized. This compound [CrO(OH₂)(salen)] (1) is characterized by elemental analysis, magnetic moment measurement, IR, UV-Vis and EPR spectroscopic studies. Measured room temperature (RT) magnetic moment value is 2.96 BM for 1 indicates a d² system with a triplet ground state. The magnetic moment value rules out a large spin-orbit coupling. The RT and LNT powder EPR spectra of 1 in X-band clearly shows two lines, one around g = 1.965 and the other with larger intensity at g = 4.26 ± 0.10. The first line at g = 1.965 corresponds to the |0> ↔ |±1> transition from the Kramers doublet |±1>, while the broad and intense line at low field with the g-value of 4.26 ± 0.10 is due to the forbidden transition |−1> ↔ |+1>. Compound 1 displays two successive reductions at −0.76 and −1.63 V (versus Ag/AgCl), respectively, while it undergoes only one irreversible oxidation as evident from the well-defined anodic wave at +1.48 V in its cyclic voltammogram.     

Growth engineering of Synechococcus elongatus PCC 7942 for mixotrophy under natural light conditions for improved feedstock production

Synechococcus elongatus PCC 7942 has been widely explored as cyanobacterial cell factory through genetic modifications for production of various value‐added compounds. However, successful industrial scale‐ups have not been reported for the system predominantly due to its obligate photoautotrophic metabolism and use of artificial light in photobioreactors. Hence, engineering the organism to perform mixotrophy under natural light could serve as an effective solution. Thus, we applied a genetically engineered strain of Synechococcus elongatus PCC 7942 expressing heterologous hexose transporter gene (galP) to perform mixotrophy under natural light in a temperature controlled environmental chamber (EC). We systematically studied the comparative performances of these transformants using autotrophy and mixotrophy, which showed 3.4 times increase in biomass productivity of mixotrophically grown transformants over autotrophs in EC. Chlorophyll a yield was found to have decreased in mixotrophic conditions, possibly indicating reduced dependency on light for energy metabolism. Although pigment yield decreases under mixotrophy, titer was found to have improved due to increased biomass productivity. Carotenoid analysis showed that zeaxanthin is the major carotenoid produced by the species which is essential for photoprotection. Our work thus demonstrates that mixotrophy under temperature controlled natural light can serve as the viable solution to improve biomass productivity of Synechococcus elongatus PCC 7942 and for commercial production of natural or engineered value added compounds from the system. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:1182–1192, 2017     

Revisiting the ichthyodiversity of Java and Bali through DNA barcodes: taxonomic coverage,identification accuracy,cryptic diversity and identification of exotic species

Among the 899 species of freshwater fishes reported from Sundaland biodiversity hotspot, nearly 50% are endemics. The functional integrity of aquatic ecosystems is currently jeopardized by human activities, and landscape conversion led to the decline of fish populations in several part of Sundaland, particularly in Java. The inventory of the Javanese ichthyofauna has been discontinuous, and the taxonomic knowledge is scattered in the literature. This study provides a DNA barcode reference library for the inland fishes of Java and Bali with the aim to streamline the inventory of fishes in this part of Sundaland. Owing to the lack of available checklist for estimating the taxonomic coverage of this study, a checklist was compiled based on online catalogues. A total of 95 sites were visited, and a library including 1046 DNA barcodes for 159 species was assembled. Nearest neighbour distance was 28‐fold higher than maximum intraspecific distance on average, and a DNA barcoding gap was observed. The list of species with DNA barcodes displayed large discrepancies with the checklist compiled here as only 36% (i.e. 77 species) and 60% (i.e. 24 species) of the known species were sampled in Java and Bali, respectively. This result was contrasted by a high number of new occurrences and the ceiling of the accumulation curves for both species and genera. These results highlight the poor taxonomic knowledge of this ichthyofauna, and the apparent discrepancy between present and historical occurrence data is to be attributed to species extirpations, synonymy and misidentifications in previous studies.     

Class II fusion protein of alphaviruses drives membrane fusion through the same pathway as class I proteins

Viral fusion proteins of classes I and II differ radically in their initial structures but refold toward similar conformations upon activation. Do fusion pathways mediated by alphavirus E1 and influenza virus hemagglutinin (HA) that exemplify classes II and I differ to reflect the difference in their initial conformations, or concur to reflect the similarity in the final conformations? Here, we dissected the pathway of low pH–triggered E1-mediated cell–cell fusion by reducing the numbers of activated E1 proteins and by blocking different fusion stages with specific inhibitors. The discovered progression from transient hemifusion to small, and then expanding, fusion pores upon an increase in the number of activated fusion proteins parallels that established for HA-mediated fusion. We conclude that proteins as different as E1 and HA drive fusion through strikingly similar membrane intermediates, with the most energy-intensive stages following rather than preceding hemifusion. We propose that fusion reactions catalyzed by all proteins of both classes follow a similar pathway.     

A Novel Interaction of Ecdysoneless (ECD) Protein with R2TP Complex Component RUVBL1 Is Required for the Functional Role of ECD in Cell Cycle Progression

Ecdysoneless (ECD) is an evolutionarily conserved protein whose germ line deletion is embryonic lethal. Deletion of Ecd in cells causes cell cycle arrest, which is rescued by exogenous ECD, demonstrating a requirement of ECD for normal mammalian cell cycle progression. However, the exact mechanism by which ECD regulates cell cycle is unknown. Here, we demonstrate that ECD protein levels and subcellular localization are invariant during cell cycle progression, suggesting a potential role of posttranslational modifications or protein-protein interactions. Since phosphorylated ECD was recently shown to interact with the PIH1D1 adaptor component of the R2TP cochaperone complex, we examined the requirement of ECD phosphorylation in cell cycle progression. Notably, phosphorylation-deficient ECD mutants that failed to bind to PIH1D1 in vitro fully retained the ability to interact with the R2TP complex and yet exhibited a reduced ability to rescue Ecd-deficient cells from cell cycle arrest. Biochemical analyses demonstrated an additional phosphorylation-independent interaction of ECD with the RUVBL1 component of the R2TP complex, and this interaction is essential for ECD''s cell cycle progression function. These studies demonstrate that interaction of ECD with RUVBL1, and its CK2-mediated phosphorylation, independent of its interaction with PIH1D1, are important for its cell cycle regulatory function.     

Improved Heterojunction Quality in Cu2O-based Solar Cells Through the Optimization of Atmospheric Pressure Spatial Atomic Layer Deposited Zn1-xMgxO

Atmospheric pressure spatial atomic layer deposition (AP-SALD) was used to deposit n-type ZnO and Zn_1-xMg_xO thin films onto p-type thermally oxidized Cu₂O substrates outside vacuum at low temperature. The performance of photovoltaic devices featuring atmospherically fabricated ZnO/Cu₂O heterojunction was dependent on the conditions of AP-SALD film deposition, namely, the substrate temperature and deposition time, as well as on the Cu₂O substrate exposure to oxidizing agents prior to and during the ZnO deposition. Superficial Cu₂O to CuO oxidation was identified as a limiting factor to heterojunction quality due to recombination at the ZnO/Cu₂O interface. Optimization of AP-SALD conditions as well as keeping Cu₂O away from air and moisture in order to minimize Cu₂O surface oxidation led to improved device performance. A three-fold increase in the open-circuit voltage (up to 0.65 V) and a two-fold increase in the short-circuit current density produced solar cells with a record 2.2% power conversion efficiency (PCE). This PCE is the highest reported for a Zn_1-xMg_xO/Cu₂O heterojunction formed outside vacuum, which highlights atmospheric pressure spatial ALD as a promising technique for inexpensive and scalable fabrication of Cu₂O-based photovoltaics.     

Attenuation of Dichlorvos-Induced Microglial Activation and Neuronal Apoptosis by 4-Hydroxy TEMPO

The neurotoxic consequences of acute high-level as well as chronic low-level organophosphates exposure are associated with a range of abnormalities in nerve functions. Previously, we have shown that after 24 h of dichlorvos exposure, microglia become activated and secrete pro-inflammatory molecules like nitric oxide, tumour necrosis factor-α and interleukin-1β. Here, we extended our findings and focused on the neuronal damage caused by dichlorvos via microglial activation. For this, neurons and microglia were isolated separately from 1-day-old Wistar rat pups. Microglia were treated with dichlorvos for 24 h and supernatant was collected (dichlorvos-induced conditioned medium, DCM). However, when 4-hydroxy TEMPO (4-HT) pretreatment was given, we observed significant attenuation of dichlorvos-induced microglial activation; we also collected the supernatant of this culture (4-HT + DCM, TDCM). Next, we checked the effects of DCM on neurons and found heavy loss in viability as evident from NF-H immunostaining and MTT results, whereas dichlorvos alone-treated neurons showed comparatively less damage. However, we observed significant increase in neuronal viability when cells were treated with TDCM. Semi-quantitative PCR and western blot results revealed significant increase in p53, Bax and cytochrome c levels along with caspase 3 activation after 24 h of DCM treatment. However, TDCM-treated neurons showed significant decrease in the expression of these pro-apoptotic molecules. Taken together, these findings suggest that 4-HT can significantly attenuate dichlorvos-induced microglial activation and prevent apoptotic neuronal cell death.