Physiological short-term response to sudden salinity change in the Senegalese sole (Solea senegalensis)

The physiological responses of Senegalese sole to a sudden salinity change were investigated. The fish were first acclimated to an initial salinity of 37.5 ppt for 4 h. Then, one group was subjected to increased salinity (55 ppt) while another group was subjected to decreased salinity (5 ppt). The third group (control group) remained at 37.5 ppt. We measured the oxygen consumption rate, osmoregulatory (plasma osmolality, gill and kidney Na+,K+-ATPase activities) and stress (plasma cortisol and metabolites) parameters 0.5 and 3 h after transfer. Oxygen consumption at both salinities was higher than for the control at both sampling times. Gill Na+,K+-ATPase activity was significantly higher for the 55 ppt salinity at 0.5 h. Plasma osmolality decreased in the fish exposed to 5 ppt at the two sampling times but no changes were detected for high salinities. Plasma cortisol levels significantly increased at both salinities, although these values declined in the low-salinity group 3 h after transfer. Plasma glucose at 5 ppt salinity did not vary significantly at 0.5 h but decreased at 3 h, while lactate increased for both treatments at the first sampling time and returned to the control levels at 3 h. Overall, the physiological response of S. senegalensis was immediate and involved a rise in oxygen consumption and plasma cortisol values as well as greater metabolite mobilization at both salinities

Genomics: applications to Antarctic ecosystems

Biological research in Antarctica has made considerable progress in science over recent decades. As little as 50 years ago, there was scant knowledge even of the species inhabiting the region. Since then, understanding has developed rapidly, across diverse disciplines including physiology, biochemistry, ecology and biogeography. Some dramatic global-scale discoveries and advances have been made, including the characterisation of antifreeze proteins from notothenioid fish and the finding that some fish lack a heat shock response, the identification of microbial communities living within the surface layers of rocks and description of the simplest faunal communities known, the identification that possibly the fastest environmental and ecological change on earth is occurring in Antarctic lakes, and that the biodiversity of the Southern Ocean is much greater than previously thought. Findings such as these have made biology in cold extreme environments one of the most stimulating areas for research in recent decades. Now, the advent and widespread applicability of the novel genomic technologies promise to move us into a period of equally, or possibly even more, rapid advance. At present, genomic information on Antarctic species is limited mainly to a number of fish species and microbes. However, an increasing number of Antarctic genomics projects are being funded and will significantly increase the amount of molecular information available on a much wider range of species in the near future. Hence it is timely to review progress so far in the use of genomic methods in Antarctic research and identify exciting prospects for dramatic future advances