Search Results (4)

Given their small size and low value in commercial fishing and aquaculture, little is known about the seasonal spatial distribution patterns and characteristics of the bobtail squid Euprymna berryi and Euprymna morsei in seas around China. Thus, we conducted seasonal bottom-trawling surveys in the southern Yellow and East China Seas during 2018 and 2019. Our results showed that E. berryi migrated from inshore areas (Yushan fishing grounds) during the summer and autumn to offshore areas (Wentai fishing grounds) during the winter. In contrast, E. morsei migrated from shallower water areas during the spring to deeper water areas during the winter. The highest abundance of E. berryi versus E. morsei was found in areas where temperatures were 25.29–28.02 °C compared with 19.54 °C (33.43–34.04‰ versus 34.43‰), respectively, during the summer; 20.99–21.69 °C compared with 21.98–22.70 °C (34.07–34.50‰ versus 33.80–33.60‰), respectively, during autumn; and 17.13–20.36 °C compared with 10.51–13.49 °C (34.23–34.46‰ versus 31.69–33.42‰), respectively, during winter. We predict that suitable habitats for E. berryi would expand more northward under SSP585-2050, whereas those for E. morsei would shrink into more northern locations under SSP370-2100 and SSP585-2100. The SSP245-2100 and SSP585-2100 scenarios had the most negative impacts on the distributions of both species. Such insights improve our understanding of the population dynamics and habitat requirements of both species to support their population management and exploitation in response to future climate change. Full article

Cephalopods’ remarkable behavior and complex neurobiology make them valuable comparative model organisms, but studies aimed at enhancing welfare of captive cephalopods remain uncommon. Increasing regulation of cephalopods in research laboratories has resulted in growing interest in welfare-oriented refinements, including analgesia and anesthesia. Although general and local anesthesia in cephalopods have received limited prior study, there have been no studies of systemic analgesics in cephalopods to date. Here we show that analgesics from several different drug classes may be effective in E. berryi. Buprenorphine, ketorolac and dexmedetomidine, at doses similar to those used in fish, showed promising effects on baseline nociceptive thresholds, excitability of peripheral sensory nerves, and on behavioral responses to transient noxious stimulation. We found no evidence of positive effects of acetaminophen or ketamine administered at doses that are effective in vertebrates. Bioinformatic analyses suggested conserved candidate receptors for dexmedetomidine and ketorolac, but not buprenorphine. We also show that rapid general immersion anesthesia using a mix of MgCl₂ and ethanol was successful in E. berryi at multiple age classes, similar to findings in other cephalopods. These data indicate that systemic analgesia and general anesthesia in Euprymna berryi are achievable welfare enhancing interventions, but further study and refinement is warranted. Full article

The Vibrio fischeri–Euprymna scolopes symbiosis has become a powerful model for the study of specificity, initiation, and maintenance between beneficial bacteria and their eukaryotic partner. In this invertebrate model system, the bacterial symbionts are acquired every generation from the surrounding seawater by newly hatched squid. These symbionts colonize a specialized internal structure called the light organ, which they inhabit for the remainder of the host’s lifetime. The V. fischeri population grows and ebbs following a diel cycle, with high cell densities at night producing bioluminescence that helps the host avoid predation during its nocturnal activities. Rhythmic timing of the growth of the symbionts and their production of bioluminescence only at night is critical for maintaining the symbiosis. V. fischeri symbionts detect their population densities through a behavior termed quorum-sensing, where they secrete and detect concentrations of autoinducer molecules at high cell density when nocturnal production of bioluminescence begins. In this review, we discuss events that lead up to the nocturnal acidification of the light organ and the cues used for pre-adaptive behaviors that both host and symbiont have evolved. This host–bacterium cross talk is used to coordinate networks of regulatory signals (such as quorum-sensing and bioluminescence) that eventually provide a unique yet stable environment for V. fischeri to thrive and be maintained throughout its life history as a successful partner in this dynamic symbiosis. Full article

Quorum sensing is an intercellular form of communication that bacteria use to coordinate group behaviors such as biofilm formation and the production of antibiotics and virulence factors. The term quorum sensing was originally coined to describe the mechanism underlying the onset of luminescence production in cultures of the marine bacterium Vibrio fischeri. Luminescence and, more generally, quorum sensing are important for V. fischeri to form a mutualistic symbiosis with the Hawaiian bobtail squid, Euprymna scolopes. The symbiosis is established when V. fischeri cells migrate via flagella-based motility from the surrounding seawater into a specialized structure injuvenile squid called the light organ. The cells grow to high cell densities within the light organ where the infection persists over the lifetime of the animal. A hallmark of a successful symbiosis is the luminescence produced by V. fischeri that camouflages the squid at night by eliminating its shadow within the water column. While the regulatory networks governing quorum sensing are critical for properly regulating V. fischeri luminescence within the squid light organ, they also regulate luminescence-independent processes during symbiosis. In this review, we discuss the quorum-sensing network of V. fischeri and highlight its impact at various stages during host colonization. Full article