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Bacterial small RNAs (sRNAs) are well known to modulate gene expression by base pairing with trans‐encoded transcripts and are typically non‐coding. However, several sRNAs have been reported to also contain an open reading frame and thus are considered dual‐function RNAs. In this study, we discovered a dual‐function RNA from Vibrio cholerae, called VcdRP, harboring a 29 amino acid small protein (VcdP), as well as a base‐pairing sequence. Using a forward genetic screen, we identified VcdRP as a repressor of cholera toxin production and link this phenotype to the inhibition of carbon transport by the base‐pairing segment of the regulator. By contrast, we demonstrate that the VcdP small protein acts downstream of carbon transport by binding to citrate synthase (GltA), the first enzyme of the citric acid cycle. Interaction of VcdP with GltA results in increased enzyme activity and together VcdR and VcdP reroute carbon metabolism. We further show that transcription of vcdRP is repressed by CRP allowing us to provide a model in which VcdRP employs two different molecular mechanisms to synchronize central metabolism in V. cholerae.

The marine environment of Mumbai and Jawaharlal Nehru ports was monitored for some environmental and biological parameters during three different periods between 2001 and 2002. The results are compared with the records available since 1960s. With the passage of time the environmental status underwent changes, probably due to the increase in anthropogenic activities in the metropolis. The nutrient level especially the nitrate concentration has increased gradually over the years with a simultaneous decrease in dissolved oxygen, indicating increase in the biological activity. Characterization of this environment based on Assessment of Estuarine Trophic Status (ASSETS) model indicates that the current status is poor and may get worsen in future if no appropriate management policies are put into place.

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Rapid and species-specific detection, and quantification of pathogenic bacteria are fundamental for monitoring and assessment of the risk they pose to any ecosystem. The study employed Vibrio cholerae, a human pathogen responsible for the life-threatening diarrhoeal disease, cholera and one among the most unwanted from marine bioinvasion point of view. The present study coupled fluorescence in situ hybridization (FISH) technique, a powerful tool in molecular phylogenetic discrimination, with flow cytometry (FCM), a technique used for rapid and accurate quantification of both viable but non-cultivable and non-viable microorganisms. The FISH-FCM technique was used for the first time to quantify V. cholerae (includes cultivable and non-cultivable) from different geographic regions of Southeast Asia (Brunei, Indonesia, Lao PDR, Myanmar, Philippines, Singapore, Thailand, Vietnam) and India (Goa, west coast of India). The data acquired from the analyses provides a snap shot view of the total bacterial abundance with special reference to V. cholerae. As the method developed, it was evaluated with bacterial samples collected from different sites in Southeast Asia and India, and the application of this technique to different geographical regions appears feasible. Considering that the continuous growth of the shipping industry and ballast water as one of the primary vectors responsible for the global transport of pathogenic microorganisms, the risk they present needs immediate attention. This technique will be useful in the quick and accurate detection of specific pathogens. It may also provide significant insights to quarantine measures for Ballast Water Management.

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