Role of cyanobacteria in the persistence of Vibrio cholerae O139 in saline microcosms

Recently, a new strain of cholera, Vibrio cholerae O139, has emerged as an epidemic strain, but there is little information about its environmental reservoir. The present investigation was aimed to determine the role of cyanobacteria in the persistence of V. cholerae O139 in microcosms. An environmental isolate of V. cholerae O139 and three cyanobacteria (Anabaena sp., Nostoc sp., and Hapalosiphon sp.) were used in this study. Survival of culturable V. cholerae O139 in microcosms was monitored using taurocholate-tellurite gelatin agar medium. Viable but nonculturable V. cholerae O139 were detected using a fluorescent antibody technique. Vibrio cholerae O139 could be isolated for up to 12 days in a culturable form in association with cyanobacteria but could not be isolated in the culturable form after 2 days from control water without cyanobacteria. The viable but nonculturable V. cholerae O139 could be detected in association with cyanobacteria for up to 15 months. These results, therefore, suggest that cyanobacteria can act as a long-term reservoir of V. cholerae O139 in an aquatic environment.     

m6A‐mediated alternative splicing coupled with nonsense‐mediated mRNA decay regulates SAM synthetase homeostasis

Alternative splicing of pre‐mRNAs can regulate gene expression levels by coupling with nonsense‐mediated mRNA decay (NMD). In order to elucidate a repertoire of mRNAs regulated by alternative splicing coupled with NMD (AS‐NMD) in an organism, we performed long‐read RNA sequencing of poly(A)⁺ RNAs from an NMD‐deficient mutant strain of Caenorhabditis elegans, and obtained full‐length sequences for mRNA isoforms from 259 high‐confidence AS‐NMD genes. Among them are the S‐adenosyl‐L‐methionine (SAM) synthetase (sams) genes sams‐3 and sams‐4. SAM synthetase activity autoregulates sams gene expression through AS‐NMD in a negative feedback loop. We furthermore find that METT‐10, the orthologue of human U6 snRNA methyltransferase METTL16, is required for the splicing regulation in␣vivo, and specifically methylates the invariant AG dinucleotide at the distal 3′ splice site (3′SS) in␣vitro. Direct RNA sequencing coupled with machine learning confirms m⁶A modification of endogenous sams mRNAs. Overall, these results indicate that homeostasis of SAM synthetase in C. elegans is maintained by alternative splicing regulation through m⁶A modification at the 3′SS of the sams genes.     

Pregnant Women in and Around Dhaka City: Are Their Children at Risk of Developing Congenital Rubella Syndrome?

Rubella Virus (RUBV) is a common cause of childhood rash and fever in non-immunized populations, and its public health importance relates to teratogenic effects of primary rubella infection in women with early pregnancy. Infection of the fetus may lead to congenital rubella syndrome (CRS). This work aimed to assess the degree of risk associated in acquiring rubella virus infection by the women during pregnancy and developing CRS among their children in Bangladesh. The study population (n = 275) included pregnant mothers (15–38 years) from various socioeconomic backgrounds attending a women health care based hospital. All subjects were personally interviewed, clinically examined and a standardized questionnaire was filled up for each of them. From each participant 3 ml blood was taken and serum was separated. Commercially available ELISA kit was used for the qualitative and quantitative determination of IgM and IgG class antibodies against RUBV in collected serum samples. 209 women were found to contain detectable level of antiRUBV IgG antibodies, but did not possess IgM antibodies against rubella. Only 9% participants were vaccinated previously against rubella virus among the whole antenatal population studied. Ninety-two percent of these vaccinated pregnant women contained serum anti-rubella IgG antibody which was significantly (P = 0.05) higher than that of the nonvaccinated study population (75%). Pregnant women from lower middle and poor socioeconomic class had significantly (P = 0.05) more intra uterine growth retardation (IUGR) of fetus than the upper middle class. 20% of the women of child bearing age examined in this work were not yet exposed to RUBV and at risk of acquiring this virus during pregnancy and subsequently transmitting the virus to the fetus. Our work demonstrates rubella attack rate among antenatal population in Bangladesh as 14.5 in 1000 during pregnancy. A proper and reliable vaccination policy against rubella virus is not yet adopted at the national level in many developing countries including Bangladesh. This work identifies the requirement of detailed study for the identification of intrauterine rubella infection and its related influence on perinatal morbidity and mortality. Thorough epidemiological studies are also considered necessary prior to the development and acceptance of national immunization program against rubella virus in Bangladesh.     

Local bacteriophage isolates showed anti- Escherichia coli O157:H7 potency in an experimental ligated rabbit ileal loop model

Escherichia coli O157:H7 is considered among the most important recently emerged food-borne bacteria causing severe hemorrhagic diarrhea. Antibiotic treatment is not recommended as a prospective curative agent against this pathogen. Therefore, potency assessment of the local lytic phage isolates infecting E. coli O157:H7 as an alternate remedy to antibiotics was the principal concern of this study. Phage isolates against E. coli O157:H7 were checked by polymerase chain reaction for the presence of the virulence genes stx1 and stx2, and the safe phages were further screened in vitro for their capacity as biocontrol agents. Two bacteriophage strains, namely PAH6 and P2BH2, that had expressed potential antibacterial activity (P?< 0.05) in vitro were selected for in vivo testing in ligated rabbit ileal loop models. Both phage isolates were capable of decreasing fluid accumulation in rabbit ileal loops along with reducing bacterial growth (r = 0.992). Combined application of the phages was found most satisfactory, reducing seven?log cycles of bacterial growth. Consistent results in both in vivo and in vitro experiments demonstrate the applicability of bacteriophages as a rapid response tool against E.?coli O157:H7. To our knowledge, this is the first successful application of the rabbit ileal loop test for therapeutic evaluation of bacteriophages.     

Methylglyoxal-induced stomatal closure accompanied by peroxidase-mediated ROS production in Arabidopsis

Methylglyoxal (MG) is an oxygenated short aldehyde and a glycolytic intermediate that accumulates in plants under environmental stresses. Being a reactive α-oxoaldehyde, MG may act as a signaling molecule in plants during stresses. We investigated whether MG induces stomatal closure, reactive oxygen species (ROS) production, and cytosolic free calcium concentration ([Ca2?](cyt)) to clarify roles of MG in Arabidopsis guard cells. MG induced production of ROS and [Ca2?](cyt) oscillations, leading to stomatal closure. The MG-induced stomatal closure and ROS production were completely inhibited by a peroxidase inhibitor, salicylhydroxamic acid (SHAM), but were not affected by an NAD(P)H oxidase mutation, atrbohD atrbohF. Furthermore, the MG-elicited [Ca2?](cyt) oscillations were significantly suppressed by SHAM but not by the atrbohD atrbohF mutation. Neither endogenous abscisic acid nor endogenous methyl jasmonate was involved in MG-induced stomatal closure. These results suggest that intrinsic metabolite MG can induce stomatal closure in Arabidopsis accompanied by extracellular ROS production mediated by SHAM-sensitive peroxidases, intracellular ROS accumulation, and [Ca2?](cyt) oscillations.     

Roles of the Aspergillus nidulans UDP-galactofuranose transporter, UgtA in hyphal morphogenesis, cell wall architecture, conidiation, and drug sensitivity

Galactofuranose (Galf) is the 5-member-ring form of galactose found in the walls of fungi including Aspergillus, but not in mammals. UDP-galactofuranose mutase (UgmA, ANID_3112.1) generates UDP-Galf from UDP-galactopyranose (6-member ring form). UgmA-GFP is cytoplasmic, so the UDP-Galf residues it produces must be transported into an endomembrane compartment prior to incorporation into cell wall components. ANID_3113.1 (which we call UgtA) was identified as being likely to encode the A. nidulans UDP-Galf transporter, based on its high amino acid sequence identity with A. fumigatus GlfB. The ugtAΔ phenotype resembled that of ugmAΔ, which had compact colonies, wide, highly branched hyphae, and reduced sporulation. Like ugmAΔ, the ugtAΔ hyphal walls were threefold thicker than wild type strains (but different in appearance in TEM), and accumulated exogenous material in liquid culture. AfglfB restored wild type growth in the ugtAΔ strain, showing that these genes have homologous function. Immunostaining with EBA2 showed that ugtAΔ hyphae and conidiophores lacked Galf, which was restored in the AfglfB-complemented strain. Unlike wild type and ugmAΔ strains, some ugtAΔ metulae produced triplets of phialides, rather than pairs. Compared to wild type strains, spore production for ugtAΔ was reduced to 1%, and spore germination was reduced to half. UgtA-GFP had a punctate distribution in hyphae, phialides, and young spores. Notably, the ugtAΔ strain was significantly more sensitive than wild type to Caspofungin, which inhibits beta-glucan synthesis, suggesting that drugs that could be developed to target UgtA function would be useful in combination antifungal therapy.     

Development of Australian commercial producers of invertebrate biological control agents from 1971 to 2014

The Australian industry producing invertebrate biological control agents (BCAs) commercially was described for the first time through interviews with company owners, citrus pest management researchers and citrus growers. This industry started with citrus pest management in 1971. Over 40 years it expanded from one company and one commercial BCA to peak at nine companies operating from 2002 to 2010. A period of consolidation resulted in five companies producing 36 commercial BCAs in 2014. Annual gross sales were <AU$10 million compared to >AU$400 million spent on insecticides. Barriers to industry growth included high costs of developing new commercial BCAs partly due to regulatory costs associated with importation of new BCAs into Australia, and low adoption of commercial BCAs due to limited access to information and training. The industry responded to these barriers by collaborating with stakeholders to develop new commercial BCAs, and developing an accreditation scheme to build technical capacity and encourage adoption.     

Increase in putrescine,amine oxidase,and acrolein in plasma of renal failure patients

Since polyamines have been suggested to be one of the uremic "toxins," the levels of each polyamine, its oxidized product, acrolein, and amine oxidase in plasma of patients with renal failure were investigated. The level of putrescine was increased, whereas the level of spermine was decreased in the plasma of patients with renal failure. The patients also had increased serum amine oxidase activity leading to increased degradation of spermine. Both levels of free and protein-conjugated acrolein were also increased in plasma of patients with renal failure. The accumulated acrolein found as protein conjugates was equivalent to 180 microM, which was 6-fold higher than in plasma of normal subjects. It was found that acrolein is mainly produced by polyamine oxidase in plasma. A cell lysate containing polyamine oxidase was cytotoxic in the presence of spermine. Our results indicate that the level of acrolein is well correlated with the degree of seriousness of chronic renal failure.     

Derivation of the first clinical diagnostic models for dehydration severity in patients over five years with acute diarrhea

Diarrheal diseases lead to an estimated 1.3 million deaths each year, with the majority of those deaths occurring in patients over five years of age. As the severity of diarrheal disease can vary widely, accurately assessing dehydration status remains the most critical step in acute diarrhea management. The objective of this study is to empirically derive clinical diagnostic models for assessing dehydration severity in patients over five years with acute diarrhea in low resource settings. We enrolled a random sample of patients over five years with acute diarrhea presenting to the icddr,b Dhaka Hospital. Two blinded nurses independently assessed patients for symptoms/signs of dehydration on arrival. Afterward, consecutive weights were obtained to determine the percent weight change with rehydration, our criterion standard for dehydration severity. Full and simplified ordinal logistic regression models were derived to predict the outcome of none (<3%), some (3–9%), or severe (>9%) dehydration. The reliability and accuracy of each model were assessed. Bootstrapping was used to correct for over-optimism and compare each model’s performance to the current World Health Organization (WHO) algorithm. 2,172 patients were enrolled, of which 2,139 (98.5%) had complete data for analysis. The Inter-Class Correlation Coefficient (reliability) was 0.90 (95% CI = 0.87, 0.91) for the full model and 0.82 (95% CI = 0.77, 0.86) for the simplified model. The area under the Receiver-Operator Characteristic curve (accuracy) for severe dehydration was 0.79 (95% CI: 0.76–0.82) for the full model and 0.73 (95% CI: 0.70, 0.76) for the simplified model. The accuracy for both the full and simplified models were significantly better than the WHO algorithm (p<0.001). This is the first study to empirically derive clinical diagnostic models for dehydration severity in patients over five years. Once prospectively validated, the models may improve management of patients with acute diarrhea in low resource settings.