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Phloroglucinol-mediated Hsp70 production in crustaceans: protection against <i>Vibrio parahaemolyticus</i> in <i>Artemia franciscana</i> and <i>Macrobrachium rosenbergii</i>
Get PDFThe halophilic aquatic bacterium, Vibrio parahaemolyticus, is an important aquatic pathogen, also capable of causing acute hepatopancreatic necrosis disease (AHPND) in shrimp resulting in significant economic losses. Therefore, there is an urgent need to develop anti-infective strategies to control AHPND. The gnotobiotic Artemia model is used to establish whether a phenolic compound phloroglucinol is effective against the AHPND strain V. parahaemolyticus MO904. We found that pretreatment with phloroglucinol, at an optimum concentration (30 µM), protects axenic brine shrimp larvae against V. parahaemolyticus infection and induced heat shock protein 70 (Hsp70) production (twofolds or more) as compared with the control. We further demonstrated that the Vibrio-protective effect of phloroglucinol was caused by its prooxidant effect and is linked to the induction of Hsp70. In addition, RNA interference confirms that phloroglucinol-induced Hsp70 mediates the survival of brine shrimp larvae against V. parahaemolyticus infection. The study was validated in xenic Artemia model and in a Macrobrachium rosenbergii system. Pretreatment of xenic brine shrimp larvae (30 µM) and Macrobrachium larvae (5 µM) with phloroglucinol increases the survival of xenic brine shrimp and Macrobrachium larvae against subsequent V. parahaemolyticus challenge. Taken together, our study provides substantial evidence that the prooxidant activity of phloroglucinol induces Hsp70 production protecting brine shrimp, A. franciscana, and freshwater shrimp, M. rosenbergii, against the AHPND V. parahaemolyticus strain MO904. Probably, phloroglucinol treatment might become part of a holistic strategy to control AHPND in shrimp
Bio-telemetry as an essential tool in movement ecology and marine conservation
Get PDFMarine top predators represent an essential part of marine ecosystems. They are generally regarded as “sentinels of the sea” since their presence reflects high biological productivity. However, many populations are experiencing dramatic declines attributed to various human-induced threats (e.g., pollution, climate change, overfishing), highlighting the need for effective conservation. In this review, we show that bio-telemetry can be an essential tool, not only to improve knowledge about the animals’ ecology, but also for conservation purposes. As such, we will first discuss the most important state-of-the-art devices (e.g., time-depth recorders, accelerometers, satellite tags) and illustrate how they can improve our understanding of movement ecology. We will then examine the challenges and ethical issues related to bio-telemetry, and lastly, demonstrate its enormous value in resolving present and future conservation issues
Genetic barcoding of marine zooplankton using the MinIon sequencer
Get PDFBiomonitoring is a way to determine the biodiversity and ecological status of an ecosystem. This is important in a world where species are lost at an alarming rate. Animal species can be identified during biomonitoring with various methods. One of these is metabarcoding which uses genetic markers isolated from a DNA extract from the biological community under study. These can then be sequenced with one of the many available platforms. Recently, the British company Oxford Nanopore Technologies has developed a revolutionary technology (MinION) has made sequencing much more accessible. In this research, it was investigated whether it is possible to use this MinION sequencer for metabarcoding of marine zooplankton communities. Each step of the protocol was optimised, after which it was applied to samples taken during a biomonitoring campaign on the North Sea. Different DNA extraction techniques are tested, after which PCR amplification and purification are optimized by selection of an optimal primer set, PCR master mix, inhibition prevention measures and purification protocols. The amplicons were then sequenced and subdivided into species using a reference database. Finally, a comparison was made with a ZooScan analysis in which species are determined based on their morphology. The results largely conform to ZooScan determinations and show no discrepancies from what was found in the literature. Although further research in data processing is required, it can be concluded that metabarcoding with MinION sequencing is a valuable innovation in the field of biomonitoring
