Electronic structure, optical and photocatalytic performance of SiC-MX2 (M = Mo, W and X = S, Se) van der Waals heterostructures.

The stacking of monolayers in the form of van der Waals heterostructures is a useful strategy for band gap engineering and the control of dynamics of excitons for potential nano-electronic devices. We performed first-principles calculations to investigate the structural, electronic, optical and photocatalytic properties of the SiC-MX2 (M = Mo, W and X = S, Se) van der Waals heterostructures. The stability of most favorable stacking is confirmed by calculating the binding energy and phonon spectrum. SiC-MoS2 is found to be a direct band gap type-II semiconducting heterostructure. Moderate in-plane tensile strain is used to achieve a direct band gap with type-II alignment in the SiC-WS2, SiC-MoSe2 and SiC-WSe2 heterostructures. A difference in the ionization potential of the corresponding monolayers and interlayer charge transfer further confirmed the type-II band alignment in these heterostructures. Furthermore, the optical behaviour is investigated by calculation of the absorption spectra in terms of ε2(ω) of the heterostructures and the corresponding monolayers. The photocatalytic response shows that the SiC-Mo(W)S2 heterostructures can oxidize H2O to O2. An enhanced photocatalytic performance with respect to the parent monolayers makes the SiC-Mo(W)Se2 heterostructures promising candidates for water splitting.

Comprehensive analysis of CCCH-type zinc finger gene family in citrus (Clementine mandarin) by genome-wide characterization.

The CCCH-type zinc finger proteins comprise a large gene family of regulatory proteins and are widely distributed in eukaryotic organisms. The CCCH proteins have been implicated in multiple biological processes and environmental responses in plants. Little information is available, however, about CCCH genes in plants, especially in woody plants such as citrus. The release of the whole-genome sequence of citrus allowed us to perform a genome-wide analysis of CCCH genes and to compare the identified proteins with their orthologs in model plants. In this study, 62 CCCH genes and a total of 132 CCCH motifs were identified, and a comprehensive analysis including the chromosomal locations, phylogenetic relationships, functional annotations, gene structures and conserved motifs was performed. Distribution mapping revealed that 54 of the 62 CCCH genes are unevenly dispersed on the nine citrus chromosomes. Based on phylogenetic analysis and gene structural features, we constructed 5 subfamilies of 62 CCCH members and integrative subfamilies from citrus, Arabidopsis, and rice, respectively. Importantly, large numbers of SNPs and InDels in 26 CCCH genes were identified from Poncirus trifoliata and Fortunella japonica using whole-genome deep re-sequencing. Furthermore, citrus CCCH genes showed distinct temporal and spatial expression patterns in different developmental processes and in response to various stress conditions. Our comprehensive analysis of CleC3Hs is a valuable resource that further elucidates the roles of CCCH family members in plant growth and development. In addition, variants and comparative genomics analyses deepen our understanding of the evolution of the CCCH gene family and will contribute to further genetics and genomics studies of citrus and other plant species.

Evaluation of Entomopathogenic Nematodes against Red Palm Weevil, Rhynchophorus ferrugineus (Olivier) (Coleoptera: Curculionidae).

Entomopathogenic nematodes play a pivotal role as biocontrol agents for different species of insect pests, including the red palm weevil. In the current investigation, the infective capabilities of four species of entomopathogenic nematodes, including Hetrerorhabditis bacteriophora, Steinernema feltiae, Steinernema glaseri, and Steinernema carpocapsae, were evaluated against larvae, pupae, and adult red palm weevil under laboratory and field conditions. The pathogenic potential of selected nematode species was assessed based on dissection and adult emergence of weevils. Our results indicated that S. carpocapsae and H. bacteriophora, with a respective 94.68 and 92.68% infection rate, were the most effective EPN species against red palm weevil larvae. Focusing on adult emergence, the aforementioned EPNs were comparatively less pathogenic and resulted in 63.60 and 60.20% infested pupae, respectively. It is noted that adult emergence is the better option to evaluate the pathogenic potential of EPNs, compared with the dissection of insects. The S. carpocapsae was found to be most effective against the 6th instar larvae of the red palm weevil and caused 100% mortality at 240 h after treatment. On the other hand, S. glaseri and S. feltiae were found to be the least pathogenic and caused 70 and 76% mortality, respectively. All of the evaluated nematode species were found to be highly infective under field conditions. The S. carpocapsae was found to be the most pathogenic, causing 83.60% mortality of the red palm weevil. However, the tested nematodes were found most effective against larvae, followed by adult weevils, but their effect was minimal against the pupae of red palm weevils. Based on these findings, we conclude that the S. carpocapsae and H. bacteriophora could be used as a sustainable option for the efficient management of the red palm weevil.

Genome-wide identification, characterization and expression analysis of calmodulin-like (CML) proteins in tomato (Solanum lycopersicum).

Calcium (Ca(2+)) has emerged as a significant secondary messenger that regulates the activities of hormonal and environmental signals that are associated with biotic and abiotic stresses. Ca(2+) binding proteins typically contain a Ca(2+) binding EF-hand (a helix-loop-helix structure) motif. In this study, tomato genes encoding calmodulin-like (CML) proteins that possess EF-hand motifs and no other identifiable functional domains were analyzed. Using genome analysis and BLAST searches in database, 52 CML genes were identified in tomato. Comprehensive analyses, including evolutionary relationships, gene structures, chromosomal locations, functional annotations, and gene duplications, were performed. Distribution mapping exhibited that 52 SlCML proteins containing different intron/exon patterns were unevenly distributed among ten chromosomes. In addition, 24 SlCML proteins were predicted as segmentally duplicated. Conserved motifs, promoter cis-regulatory elements, organ-based expression patterns and expression analyses indicated the potential responsiveness of SlCML proteins to abiotic stresses and phytohormones. These results illustrate the complexity of the CML gene family and indicate a potential vital role for these molecules in tomato growth and development as Ca(2+) signal transducers.

Genetic regulation of flowering time in annual and perennial plants.

Flowering time plays a significant role in the reproductive success of plants. So far, five major pathways to flowering have been characterized in Arabidopsis, including environmental induction through photoperiod, vernalization, and gibberellins and autonomous floral iation, and aging by sequentially operating miRNAs (typically miR156 and miR172) responding to endogenous cues. The balance of signals from these pathways is integrated by a common set of genes (FLOWERING LOCUS C, FLOWERING LOCUS T, LEAFY, and SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1) that determine the flowering time. Recent studies have indicated that epigenetic modification, alternative splicing, antisense RNA and chromatin silencing regulatory mechanisms play an important role in this process by regulating related flowering gene expression. In this review, we discuss the current understanding in genetic regulation of the phase transition from vegetative to reproductive growth by using Arabidopsis as a model. We also describe how this knowledge has been successfully applied for identifying homologous genes from perennial crops. Furthermore, detailed analysis of the similarities and differences between annual and perennial plants flowering will help elucidate the mechanisms of perennial plant maturation and regulation of floral initiation.

Possible involvement of locus-specific methylation on expression regulation of leafy homologous gene (CiLFY) during precocious trifoliate orange phase change process.

DNA methylation plays an essential role in regulating plant development. Here, we described an early flowering trifoliate orange (precocious trifoliate orange, Poncirus trifoliata L. Raf) was treated with 5-azacytidine and displayed a number of phenotypic and developmental abnormalities. These observations suggested that DNA methylation might play an important role in regulating many developmental pathways including early flowering trait, and then the expression level of five key or integrated citrus flowering genes were analyzed. Our results showed that flowering locus T (CiFT) relative expression level was increased with the increasing concentrations of 5-AzaC. However, leafy (CiLFY), APETELA1 (CiAP1), terminal flower1 (CiTFL1), and flowering locus C (CiFLC) showed highest relative expression levels at 250 µΜ treatment, while decreased sharply at higher concentrations. In order to further confirm DNA methylation affects the expression of these genes, their full-length sequences were isolated by genome-walker method, and then was analyzed by using bioinformatics tools. However, only one locus-specific methylation site was observed in CiLFY sequence. Therefore, DNA methylation level of the CiLFY was investigated both at juvenile and adult stages of precocious trifoliate orange by bisulfate sequencing PCR; it has been shown that the level of DNA methylation was altered during phase change. In addition, spatial and temporal expression patterns of CiLFY promoter and a series of 5' deletions were investigated by driving the expression of a ß-glucuronidase reporter gene in Arabidopsis. Exogenous GA3 treatment on transgenic Arabidopsis revealed that GA3 might be involved in the developmental regulation of CiLFY during flowering process of precocious trifoliate orange. These results provided insights into the molecular regulation of CiLFY gene expression, which would be helpful for studying citrus flowering.

Randomized controlled trial of standard versus double dose cotrimoxazole for childhood pneumonia in Pakistan.

OBJECTIVE: Increasing concern over bacterial resistance to cotrimoxazole, which is recommended by WHO as a first-line drug for treating non-severe pneumonia, led to the suggestion that this might not be optimal therapy. However, changing to alternative antimicrobial agents, such as amoxicillin, is costly. We compared the clinical efficacy of twice-daily cotrimoxazole in standard versus double dosage for treating non-severe pneumonia in children. METHODS: A randomized controlled multicentre trial was implemented in seven hospital outpatient departments and two community health programmes. A total of 1143 children aged 2-59 months with non-severe pneumonia were randomly allocated to receive 4 mg trimethoprim plus 20 mg sulfamethoxazole/kg of body weight or 8 mg trimethoprim plus 40 mg sulfamethoxazole/kg of body weight orally twice-daily for 5 days Treatment failure occurred when a child required a change of therapy, died or was lost to follow-up. Children required a change of therapy if their condition worsened (they developed chest indrawing or danger signs) or if at 48 hours after enrollment, their clinical condition was the same (defined as having a respiratory rate that was 5 breaths/minute higher or lower than at the time of enrollment). FINDINGS: The results of 1134 children were analysed: 578 were assigned to the standard dose of cotrimoxazole and 556 to the double dose. Treatment failed in 112 children (19.4%) in the standard group and 118 (21.2%) in the double-dose group (relative risk 1.10; 95% confidence interval = 0.87-1.37). Using multivariate analysis we found that treatment was more likely to fail in children who were not given the medicine correctly (P = 0.001), in those younger than 12 months (P = 0.004), those who had used antibiotics previously (P = 0.002), those whose respiratory rate was > or =20 breaths/minute above the age-specific cut-off point (P = 0.006), and those from urban areas (P = 0.042). CONCLUSION: Both standard and double strength cotrimoxazole were equally effective in treating non-severe pneumonia. Close follow-up of patients is essential to prevent worsening of disease. Definitions of clinical failure need to be more specific. Surveillance in both rural and urban areas is essential in the development of treatment policies that are based on clinical outcomes.