Temperature regulates sex determination and growth in the paralichthid flatfish California halibut.

California halibut (Paralichthys californicus) is a candidate species for aquaculture and stock enhancement. These applications rely on sex control, either to maximize the production of faster growing females or to match sex ratios in the wild. Other paralichthids exhibit temperature-dependent sex determination (TSD), but the presence and pattern of TSD is not well defined in California halibut. Juvenile California halibut were cultured at three distinct temperatures (15°C, 19°C, and 23°C) through the developmental period presumed to be thermosensitive based on findings from congeners. Sex ratios were quantified in each treatment using phenotypic sex identification techniques applied early (molecular biomarkers; 51-100 mm total length [TL]) and late (visual examination of the gonads; ≥100 mm TL) in the juvenile phase. Both techniques indicated similar sex determination trends at each temperature, with overall sex ratios assessed as 49.9% male at 15°C, 74.5% male at 19°C, and 98.2% male at 23°C. Growth rates were highest at 23°C and lowest at 15°C, with intrinsically fast- and slow-growing individuals at all temperatures. At 15°C and 19°C, females comprised a higher proportion among the fast growers than they did among the slow growers. These data show that California halibut exhibit TSD, with temperatures of 19°C and 23°C masculinizing fish while 15°C appears to produce a 1:1 sex ratio. This study will help optimize sex ratios and growth in hatcheries through thermal manipulation. Furthermore, the developed biomolecular tools and identified temperature thresholds will be important in future work to understand the influence of global warming on wild population demographics.

Metabolomic tools used in marine natural product drug discovery.

Introduction: The marine environment is a very promising resource for natural product research, with many of these reaching the market as new drugs, especially in the field of cancer therapy as well as the drug discovery pipeline for new antimicrobials. Exploitation for bioactive marine compounds with unique structures and novel bioactivity such as the isoquinoline alkaloid; trabectedin, the polyether macrolide; halichondrin B, and the peptide; dolastatin 10, requires the use of analytical techniques, which can generate unbiased, quantitative, and qualitative data to benefit the biodiscovery process. Metabolomics has shown to bridge this understanding and facilitate the development of new potential drugs from marine sources and particularly their microbial symbionts.Areas covered: In this review, articles on applied secondary metabolomics ranging from 1990-2018 as well as to the last quarter of 2019 were probed to investigate the impact of metabolomics on drug discovery for new antibiotics and cancer treatment.Expert opinion: The current literature review highlighted the effectiveness of metabolomics in the study of targeting biologically active secondary metabolites from marine sources for optimized discovery of potential new natural products to be made accessible to a R&D pipeline.

Postprandial reactive hypoglycaemia: varying presentation patterns on extended glucose tolerance tests and possible therapeutic approaches.

Reactive hypoglycemia is a state characterised by sympathetic or neuroglycopenic symptoms associated with hypoglycaemia in the postprandial state resulting in considerable distress to the patient. It is our practice to carry out either extended glucose tolerance tests (eGTTs) or mixed meal tests in these patients. We describe two patients who experienced hypoglycaemic symptoms early and late during eGTT. The patient who experienced symptoms early, in contrast to the patient who presented with late symptoms, did not possess any characteristics of the metabolic syndrome. Based on clinical symptoms, glucose, insulin, and free fatty acid (FFA) levels, we speculate on possible mechanisms that may have accounted for each of their presentation patterns. We then discuss low glycaemic index diet which will be the mainstay of management.