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Gaining robust in situ estimates of the growth rate of marine fish larvae is essential for understanding processes controlling year-class success and developing sustainable management strategies to maintain good environmental status. We measured the growth rate of Atlantic herring (Clupea harengus) larvae in the laboratory and compared it to the activity of aminoacyl-tRNA synthetases (AARS). Larvae were reared under controlled conditions for 20 days at three temperatures (7, 12, and 17 °C) using different prey concentrations (0.1, 0.3, and 2 prey·mL−1) of the copepod Acartia tonsa. The relationship between specific growth rates (SGR) and specific AARS activities was best described by a linear function—SGR = −0.1031 + 0.0017 · spAARS, r2 = 0.71, p < 0.05—when only larvae fed ad libitum were considered regardless of the temperature. When larvae fed with low concentrations of food were included in the analysis, the relationship was SGR = −0.0332 + 0.0010 · spAARS, r2 = 0.42, p < 0.05. This latter slope was rather low compared to other studies performed in zooplankton. We suggest protein degradation during the early life stages of fish as the cause of this low slope. We also studied SGR under food deprivation and the effect on specific AARS activities. We found rather high specific AARS activities in small individuals of early stages of fish, also suggesting protein degradation. Further research about protein degradation and turnover rates is needed in order to use AARS activity as a proxy for growth rates in field-caught larvae. [ABSTRACT FROM AUTHOR]

Brucellosis is an important global zoonosis caused by the bacterium Brucella sp. Brucellosis causes abortions, reproductive failure and reduced milk production, resulting in significant economic losses. Brucella species are reported to be resistant to antibiotics, which makes treatment difficult. The urgency of discovering new drug candidates to combat Brucella's infection necessitates the exploration of novel alternative agents with unique protein targets. Aminoacyl‐tRNA synthetases (aaRSs), which have fundamental functions in translation, inhibit this process, stop protein synthesis and ultimately inhibit bacterial growth. The purpose of this study was to isolate piperolactam A compounds from the methanol extract of Piper betle leaves that have potential as antibacterials to inhibit the growth of Brucella sp. causing brucellosis in livestock and to analyse the mechanism of inhibitory activity of piperolactam A compounds against the aaRS enzyme through a molecular docking approach in silico. Piperolactam A was isolated from P. betle by column chromatography and characterized by UV, IR, 1D and 2D NMRs and MS, then tested for their inhibition mechanism against the enzymes threonyl‐tRNA synthetase, leucyl‐tRNA synthetase (LeuRS) and methionyl‐tRNA synthetase in silico. The result in silico test is that piperolactam A has the potential to inhibit LeuRS enzyme with the greater binding affinity. [ABSTRACT FROM AUTHOR]