Strong visible photoluminescence emission of ZnO nanosheets and nanoflowers by a facile hydrothermal route.

Zinc oxide nanostructures such as nanosheets (NS) and nanoflowers (NF) were obtained by a facile hydrothermal synthesis using zinc chloride (ZnCl2) as precursor with low molar concentrations and a short synthesis time (2 h) at 200 °C. By means of X-ray diffraction and Raman spectroscopy measurements, the wurtzite-type ZnO structure was confirmed with high crystalline quality. SEM micrographs showed the influence of ZnCl2 concentration on ZnO morphology; ZnO NF were obtained at low concentrations (0.02 and 0.05 M), while ZnO NS were seen for higher concentrations (0.2-0.6 M) and their thicknesses can be estimated from 15 to 60 nm. In addition, TEM images showed a large number of pores with sizes below 15 nm in both ZnO nanostructures. Raman and photoluminescence displayed the surface defects density for ZnO nanostructures. Raman spectra showed the E1(LO) mode localized at ∼581 cm-1, associated with oxygen vacancies and zinc interstitials, being more intense for ZnO NF, while photoluminescence results showed a strong yellow-orange emission (centered from 587 to 618 nm) relative to UV emission, being more intense for ZnO NF. These properties reveal further potential for high performance luminescent devices based on ZnO NF and NS.

Genetic Relationships and Spatial Genetic Structure Among Populations of Rhodnius prolixus (Hemiptera: Reduviidae) in Colombia and Venezuela Based on Mitochondrial Cytochrome-b Sequences.

One hundred twenty Rhodnius prolixus (Stal) (Hemiptera: Reduviidae) specimens from 6 Colombian Departments and 1 Venezuelan State had 594-bp of the mitochondrial cytochrome-b gene sequenced to improve the understanding of evolutionary processes that shape the main vector of Chagas disease. The levels of genetic diversity for this species were low-medium with reference to other bugs. The genetic heterogeneity among the populations was very limited which means there has been extensive gene flow and/or very recent split processes. The overall sample as well as some individual populations showed evidence of recent population expansions (with the exception of Arauca, which yielded evidence of a bottleneck for a mismatch distribution). This expansion (11,000 or 2000-25,000 year ago depending of two procedures employed) coincides with the ending of the last intense glacial conditions during the Pleistocene and the beginning of the Holocene that had a warmer and wetter climate. Some of our autocorrelation analyses (AIDA and Genetic Landscape Interpolation Analysis) indicated local patches of high genetic similarity but no globally significant spatial structure. We did show an original haplotype distributed throughout the entirety of the geographical area studied.

Anaerobic treatment of a medium strength industrial wastewater at low-temperature and short hydraulic retention time: a pilot-scale experience.

The aim of this work was to evaluate the performance of a pilot-scale upflow anaerobic sludge blanket (UASB) reactor during the treatment of cereal-processing industry wastewater under low-temperature conditions (17 degrees C) for more than 300 days. The applied organic loading rate (OLR(appl)) was gradually increased from 4 to 6 and 8 kg COD(sol)/m3d by increasing the influent soluble chemical oxygen demand (COD(sol)), while keeping the hydraulic retention time constant (5.2 h). The removal efficiency was high (82 to 92%) and slightly decreased after increasing the influent COD(sol) and the OLR(appl). The highest removed organic loading rate (OLR(rem)) was reached when the UASB reactor was operated at 8 kg COD(sol)/m3d and it was two times higher than that obtained for an OLR(appl) of 4 kg COD(sol)/m3d. Some disturbances were observed during the experimentation. The formation of biogas pockets in the sludge bed significantly complicated the biogas production quantification, but did not affect the reactor performance. The volatile fatty acids in the effluent were low, but increased as the OLR(appl) increased, which caused an increment of the effluent COD(sol). Anaerobic treatment at low temperature was a good option for the biological pre-treatment of cereal processing industry wastewater.

Differential cooperation between regulatory sequences required for human CD53 gene expression.

CD53 is a tetraspanin protein mostly expressed in to the lymphoid-myeloid lineage. We have characterized the human CD53 gene regulatory region. Within the proximal 2 kilobases, and with opposite transcriptional orientation, is located the promoter-enhancer of a second gene, which does not affect CD53. Twenty-four copies of a CA dinucleotide repeat separate these two gene promoters. The proximal enhanceosome of the human CD53 gene is comprised between residues -266 and +84, and can be subdivided into four major subregions, two of them within exon 1. Mutational analysis identified several cooperating sequences. An Sp1 and an ets-1 site, at positions -115 and +62, respectively, are essential for transcriptional competence in all cell lines. Five other regulatory sequences have a dual role, activator or down-regulator, depending on the cell line. At the end of the non-coding exon 1, +64 to +83, there is a second ets-1 regulatory element, which is required for high level of transcription, in cooperation with the Sp1 site, in K562 and Molt-4, but not in Namalwa cells, where it functions as a repressor. This Sp1 site also cooperates with another ets-1/PU.1 site at -172. Different cell types use different regulatory sequences in the enhanceosome for the expression of the same gene.

Genomic organization, chromosomal localization, alternative splicing, and isoforms of the human synaptosome-associated protein-23 gene implicated in vesicle-membrane fusion processes.

Synaptosome-associated protein-23 (SNAP23) is a component of the cellular mechanism required for specific membrane fusion and targetting of intracellular vesicles. We have cloned the full-length human cDNA and the SNAP23 gene. The SNAP23 gene has eight exons, with the initiation codon located in exon 2, and maps to the human chromosome 15q21-22 region. The human SNAP23 gene can generate two types of message, the full-length message (SNAP23A) and a shorter message (SNAP23B). The latter is the result of alternative splicing where exon 5 is joined to exon 7 and the skipping of exon 6; it thus lacks a region that is required for non-specific binding to plasma membranes. The two isoforms, expressed as fusion proteins with glutathione-S-transferase, interact in vitro with human syntaxin 6, thus retaining the specific protein interaction required for membrane fusion. Alterations in the SNAP23 gene might be involved in neurological and other diseases with defects in vesicle-membrane fusion processes that map to 15q15-21.

Isolation and characterization of gmsti, a stress-inducible gene from soybean (Glycine max) coding for a protein belonging to the TPR (tetratricopeptide repeats) family.

In close vicinity of two fus nuclear genes (chloroplast-specific translation elongation factor cEF-G) of soybean (Glycine max) we localized a split nuclear gene coding for a protein with tetratricopeptide repeats (TPR). A full-length cDNA was sequenced (1871 nucleotides). It encodes a protein (569 amino acids) with high sequence identity to the yeast STI1 stress-inducible and the human transformation-sensitive IEF SSP 3521 protein which both carry TPR elements. The soybean gene is heat-inducible. This is the first evidence for the existence of plant genes coding for proteins which belong to the TPR family. We call the gene gmsti and the protein GMSTI in analogy to the yeast counterpart.

Cloning and sequencing of a soybean nuclear gene coding for a chloroplast translation elongation factor EF-G.

A plant nuclear gene coding for a chloroplast specific translation elongation factor EF-G (cEF-G) was cloned and sequenced for the first time. We screened two partial soybean genomic libraries with a short PCR amplified pea DNA probe constructed according to the N-terminal peptide sequence of pea chloroplast EF-G. The gene is three times split, codes for a chloroplast type transit peptide and a protein very similar to bacterial translation elongation factor EF-G. The gene is expressed as evidenced by Northern hybridisations.