Response of maize (Zea mays L.) lines carrying Wsm1, Wsm2, and Wsm3 to the potyviruses Johnsongrass mosaic virus and Sorghum mosaic virus

Maize dwarf mosaic disease is one of the most important viral diseases of maize (Zea mays L.) throughout the world. It is caused by several virus species in the family Potyviridae, genus Potyvirus, including Maize dwarf mosaic virus (MDMV), Sugarcane mosaic virus (SCMV), Johnsongrass mosaic virus (JGMV) and Sorghum mosaic virus (SrMV). Resistance to another member of the family Potyviridae, Wheat streak mosaic virus (WSMV), is conferred by three alleles (Wsm1, Wsm2, Wsm3) in the maize inbred line Pa405, and these or closely linked genes were previously shown to confer resistance to the potyviruses MDMV and SCMV. In this study, we assessed whether Wsm alleles are linked to resistance to JGMV and SrMV. Near isogenic lines (NILs) carrying one or two of the Wsm alleles introgressed into the susceptible line Oh28 and F1 progeny from NIL × Oh28 were tested for their response to JGMV and SrMV. Our results indicate that Wsm1 provides resistance to both JGMV and SrMV in a dose-dependent manner. Wsm2 and Wsm3 each provide limited resistance, and combining Wsm alleles enhances that resistance.     

Selenoneine, a Novel Selenium-Containing Compound, Mediates Detoxification Mechanisms against Methylmercury Accumulation and Toxicity in Zebrafish Embryo

The selenium (Se)-containing antioxidant selenoneine (2-selenyl-N _α,N _α,N _α-trimethyl-l-histidine) has recently been discovered to be the predominant form of organic Se in tuna blood. Although dietary intake of fish Se has been suggested to reduce methylmercury (MeHg) toxicity, the molecular mechanism of MeHg detoxification by Se has not yet been determined. Here, we report evidence that selenoneine accelerates the excretion and demethylation of MeHg, mediated by a selenoneine-specific transporter, organic cations/carnitine transporter-1 (OCTN1). Selenoneine was incorporated into human embryonic kidney HEK293 cells transiently overexpressing OCTN1 and zebrafish blood cells by OCTN1. The K _m for selenoneine uptake was 13.0 μM in OCTN1-overexpressing HEK293 cells and 9.5 μM in zebrafish blood cells, indicating high affinity of OCTN1 for selenoneine in human and zebrafish cells. When such OCTN1-expressing cells and embryos were exposed to MeHg–cysteine (MeHgCys), MeHg accumulation was decreased and the excretion and demethylation of MeHg were enhanced by selenoneine. In addition, exosomal secretion vesicles were detected in the culture water of embryos that had been microinjected with MeHgCys, suggesting that these may be responsible for MeHg excretion and demethylation. In contrast, OCTN1-deficient embryos accumulated MeHg, and MeHg excretion and demethylation were decreased. Furthermore, Hg accumulation was decreased in OCTN1-overexpressing HEK293 cells, but not in mock vector-transfected cells, indicating that selenoneine and OCTN1 can regulate MeHg detoxification in human cells. Thus, the selenoneine-mediated OCTN1 system regulates secretory lysosomal vesicle formation and MeHg demethylation.     

Tobacco Smoking and Its Association with Illicit Drug Use among Young Men Aged 15-24 Years Living in Urban Slums of Bangladesh

Background

Tobacco smoking (TS) and illicit drug use (IDU) are of public health concerns especially in developing countries, including Bangladesh. This paper aims to (i) identify the determinants of TS and IDU, and (ii) examine the association of TS with IDU among young slum dwellers in Bangladesh.

Methodology/Principal Findings

Data on a total of 1,576 young slum dwellers aged 15–24 years were extracted for analysis from the 2006 Urban Health Survey (UHS), which covered a nationally representative sample of 13,819 adult men aged 15–59 years from slums, non-slums and district municipalities of six administrative regions in Bangladesh. Methods used include frequency run, Chi-square test of association and multivariable logistic regression. The overall prevalence of TS in the target group was 42.3%, of which 41.4% smoked cigarettes and 3.1% smoked bidis. The regression model for TS showed that age, marital status, education, duration of living in slums, and those with sexually transmitted infections were significantly (p<0.001 to p<0.05) associated with TS. The overall prevalence of IDU was 9.1%, dominated by those who had drug injections (3.2%), and smoked ganja (2.8%) and tari (1.6%). In the regression model for IDU, the significant (p<0.01 to p<0.10) predictors were education, duration of living in slums, and whether infected by sexually transmitted diseases. The multivariable logistic regression (controlling for other variables) revealed significantly (p<0.001) higher likelihood of IDU (OR = 9.59, 95% CI = 5.81–15.82) among users of any form of TS. The likelihood of IDU increased significantly (p<0.001) with increased use of cigarettes.

Conclusions/Significance

Certain groups of youth are more vulnerable to TS and IDU. Therefore, tobacco and drug control efforts should target these groups to reduce the consequences of risky lifestyles through information, education and communication (IEC) programs.     

Automated analysis of courtship suppression learning and memory in Drosophila melanogaster

Study of the fruit fly, Drosophila melanogaster, has yielded important insights into the underlying molecular mechanisms of learning and memory. Courtship conditioning is a well-established behavioral assay used to study Drosophila learning and memory. Here, we describe the development of software to analyze courtship suppression assay data that correctly identifies normal or abnormal learning and memory traits of individual flies. Development of this automated analysis software will significantly enhance our ability to use this assay in large-scale genetic screens and disease modeling. The software increases the consistency, objectivity, and types of data generated.     

An Evaluation of Plotless Sampling Using Vegetation Simulations and Field Data from a Mangrove Forest

In vegetation science and forest management, tree density is often used as a variable. To determine the value of this variable, reliable field methods are necessary. When vegetation is sparse or not easily accessible, the use of sample plots is not feasible in the field. Therefore, plotless methods, like the Point Centred Quarter Method, are often used as an alternative. In this study we investigate the accuracy of different plotless sampling methods. To this end, tree densities of a mangrove forest were determined and compared with estimates provided by several plotless methods. None of these methods proved accurate across all field sites with mean underestimations up to 97% and mean overestimations up to 53% in the field. Applying the methods to different vegetation patterns shows that when random spatial distributions were used the true density was included within the 95% confidence limits of all the plotless methods tested. It was also found that, besides aggregation and regularity, density trends often found in mangroves contribute to the unreliability. This outcome raises questions about the use of plotless sampling in forest monitoring and management, as well as for estimates of density-based carbon sequestration. We give recommendations to minimize errors in vegetation surveys and recommendations for further in-depth research.     

Transorbital Sonographic Evaluation of Normal Optic Nerve Sheath Diameter in Healthy Volunteers in Bangladesh

Introduction

Measurement of optic nerve sheath diameter (ONSD) by ultrasound is increasingly used as a marker to detect raised intracranial pressure (ICP). ONSD varies with age and there is no clear consensus between studies for an upper limit of normal. Knowledge of normal ONSD in a healthy population is essential to interpret this measurement.

Methods

In a prospective observational study, ONSD was measured using a 15 MHz ultrasound probe in healthy volunteers in Chittagong, Bangladesh. The aims were to determine the normal range of ONSD in healthy Bangladeshi adults and children, compare measurements in males and females, horizontal and vertical beam orientations and left and right eyes in the same individual and to determine whether ONSD varies with head circumference independent of age.

Results

136 subjects were enrolled, 12.5% of whom were age 16 or under. Median ONSD was 4.41 mm with 95% of subjects in the range 4.25–4.75 mm. ONSD was bimodally distributed. There was no relationship between ONSD and age (≥4 years), gender, head circumference, and no difference in left vs right eye or horizontal vs vertical beam.

Conclusions

Ultrasonographic ONSD in Bangladeshi healthy volunteers has a narrow bimodal distribution independent of age (≥4 years), gender and head circumference. ONSD >4.75 mm in this population should be considered abnormal.     

The Importance of Tryptophan B28 in H2 Relaxin for RXFP2 Binding and Activation

H2 relaxin (relaxin) is a member of the insulin–relaxin superfamily and exhibits several non-reproductive functions in addition to its well-known properties as a pregnancy hormone. Over the years, the therapeutic potential of relaxin has been examined for a number of conditions. It is currently in phase III clinical trials for the treatment of acute heart failure. The 53 amino acid peptide hormone consists of two polypeptide chains (A and B) which are cross-linked by two inter-chains and one intra-A chain disulfide bridge. Although its cognate receptor is relaxin family peptide receptor (RXFP) 1, relaxin is also able to cross-react with RXFP2, for which the native ligand is INSL3. The “RXXXRXXI” motif in the B-chain of H2 relaxin is responsible for primary binding to LRR of the RXFP1 receptor (Büllesbach and Schwabe, J Biol Chem 280:14051–14056, 2005). Previous RXFP2 receptor mutation and molecular modelling studies strongly suggest that, in addition to this motif, the Trp-B28 residue in the B-chain is responsible for H2–RXFP2 interaction. To confirm this finding, here we have mutated H2 relaxin in which Trp-B28 was replaced with alanine. The synthetic relaxin analogue was then tested on cells expressing either RXFP1 or 2 to determine the affinity and potency for the respective receptors. Our results confirm that Trp-B28 in the B-chain is crucial for binding and activating RXFP2, but not for RXFP1.     

Preliminary Structure–Function Relationship Studies on Insulin-Like Peptide 5 (INSL5)

Insulin-like peptide 5 (INSL5) is a two-chain, three-disulfide bonded member of insulin/relaxin superfamily of peptides that includes insulin, insulin-like growth factor I and II (IGFI and IGFII), insulin-like peptide 3, 4, 5 and 6 (INSL3, 4, 5 and 6), relaxin-1 (H1 relaxin), -2 (H2 relaxin) and -3 (H3 relaxin). Although it is expressed in relatively high levels in the gut, its biological function remains unclear. However, recent reports suggest a significant orexigenic action and a role in the regulation of insulin secretion and β-cell homeostasis, which implies that both agonists and antagonists of the peptide may have significant therapeutic applications. Modern solid phase synthesis techniques together with regioselective disulfide bond formation were employed for a preliminary structure–function relationship study of mouse INSL5. Two point mutated analogues, mouse INSL5 A-B(R24A, W25A) and mouse INSL5 A-B(K6A, R14A, Y18A) were chemically prepared, where the residues in the B-chain that may be involved in receptor activation and affinity binding, were respectively mutated. Synthetic mouse INSL5 A-B(R24A, W25A) analogue was inactive on RXFP4, the native receptor for INSL5, suggesting Arg^B24 and Trp^B25 are probably directly involved in INSL5 receptor activation. Mouse INSL5 A-B(K6A, R14A, Y18A) analogue had both decreased affinity and potency on RXFP4 (pIC₅₀ 7.7 ± 0.2, pEC₅₀ 7.87 ± 0.18) which indicated that one or more of these residues are critical for the binding to the receptor.     

Genetic Diversity and Distribution of the Ciguatera-Causing Dinoflagellate Gambierdiscus spp. (Dinophyceae) in Coastal Areas of Japan

Background

The marine epiphytic dinoflagellate genus Gambierdiscus produce toxins that cause ciguatera fish poisoning (CFP): one of the most significant seafood-borne illnesses associated with fish consumption worldwide. So far, occurrences of CFP incidents in Japan have been mainly reported in subtropical areas. A previous phylogeographic study of Japanese Gambierdiscus revealed the existence of two distinct phylotypes: Gambierdiscus sp. type 1 from subtropical and Gambierdiscus sp. type 2 from temperate areas. However, details of the genetic diversity and distribution for Japanese Gambierdiscus are still unclear, because a comprehensive investigation has not been conducted yet.

Methods/Principal Finding

A total of 248 strains were examined from samples mainly collected from western and southern coastal areas of Japan during 2006–2011. The SSU rDNA, the LSU rDNA D8–D10 and the ITS region were selected as genetic markers and phylogenetic analyses were conducted. The genetic diversity of Japanese Gambierdiscus was high since five species/phylotypes were detected: including two reported phylotypes (Gambierdiscus sp. type 1 and Gambierdiscus sp. type 2), two species of Gambierdiscus (G. australes and G. cf. yasumotoi) and a hitherto unreported phylotype Gambierdiscus sp. type 3. The distributions of type 3 and G. cf. yasumotoi were restricted to the temperate and the subtropical area, respectively. On the other hand, type 1, type 2 and G. australes occurred from the subtropical to the temperate area, with a tendency that type 1 and G. australes were dominant in the subtropical area, whereas type 2 was dominant in the temperate area. By using mouse bioassay, type 1, type 3 and G. australes exhibited mouse toxicities.

Conclusions/Significance

This study revealed a surprising diversity of Japanese Gambierdiscus and the distribution of five species/phylotypes displayed clear geographical patterns in Japanese coastal areas. The SSU rDNA and the LSU rDNA D8–D10 as genetic markers are recommended for further use.