This study constitutes a first attempt to investigate sex differences in osmoregulatory capacity and metabolic responses in relation to hyper- and hypo-osmoregulation in the intertidal euryhaline crab Uca tangeri. Adult male and female specimens from Cadiz Bay, Spain (36°23′–37′N 6°8′–15′W), were acclimated to three different environmental salinities (12, 33 and 55 psu) during 7 days, and several parameters were assessed in haemolymph (osmolality, glucose, amino acids, triglycerides and lactate) as well as in metabolic key organs (hepatopancreas, anterior and posterior gills: glycogen, free glucose, amino acids and triglycerides). Specimens from both sex exhibited high and similar hyper- and hypo-osmoregulatory capacities. However, metabolite levels were differentially affected upon acclimation to low and high salinity in several metabolic organs and haemolymph of male and females: (i) glycogen in gills, (ii) free glucose in gills and hepatopancreas, (iii) amino acids in hepatopancreas, (iv) triglycerides in haemolymph, hepatopancreas and posterior gills, and (v) lactate in haemolymph. The results suggest the occurrence of differential metabolic adjustments upon hyper- and hypo-osmoregulation related to sex in the intertidal euryhaline crab U. tangeri.

We studied biochemical characteristics and the response to low salinity at short and long-term after feeding of alkaline phosphatase (AP) activity in hepatopancreas of the osmoregulator crab Neohelice granulata from Mar Chiquita coastal lagoon (Buenos Aires Province, Argentina) (37°32′–37°45′S 57°19′–57°26′W). The hepatopancreas exhibited a levamisole-insensitive and a levamisole-sensitive AP activity with distinct characteristics. Levamisole-insensitive activity was similar within the range of pH 7.4–9.0 and exhibited a Michaelis–Menten kinetics. Levamisole-sensitive AP activity appeared to be maximal at pH 8.5 and appeared to exhibit an allosteric kinetics. In crabs acclimated to 10 psu (hyper-regulation conditions) levamisole-insensitive and levamisole-sensitive AP activity increased (about 16-fold) over time from short term (2–4 h) to long term (120 h) after feeding while no changes occurred in crabs acclimated to 35 psu (osmoconforming conditions). The changes of AP activity along with the higher values at 120 h after feeding in 10 psu compared with those in 35 psu, and the concomitant changes in proteolytic activity, suggest a role of AP in digestive and metabolic adjustments at the biochemical level upon hyper-regulatory conditions.

Changes in hepatopancreas mass in nymphs, male and female Scorpio maurus fuscus (Scorpiones, Scorpionidae) from northern Israel, were followed through the year, and its percentage water content calculated. The hepatopancreas mass was positively correlated with body mass in males, females and nymphs, and changed significantly with season. In nymphs it ranged between 0.1549 g and 0.5351 g, in males between 0.1631 g and 0.3431 g, and in females between 0.2240 g and 0.6669 g. The hepatopancreas mass of males differed significantly from that of females during summer and autumn, and from nymphs during summer and winter. The hepatopancreas mass of nymphs differed significantly from that of females during autumn, winter and spring. In females, the hepatopancreas mass increased from autumn to spring. During that time, the embryonic diverticula (Ed) containing the embryos increase in number and size during embryogenesis. The depletion of the hepatopancreas mass is positively correlated with the Ed during the latter part of the gestation period before parturition. The percentage water content of the hepatopancreas ranged between 47.8% and 68.4%, and varied seasonally as well as between the genders. It is suggested that these changes in both hepatopancreas mass and water content are related to physiological events such as growing and moulting in nymphs, feeding and mating activities in males and the oogenetic cycle in females.

Se estudió de contenido en ácidos grasos de los lípidos totales, polares y neutros en músculo, hepatopáncreas y ovario de hembras de Penaeus kerathurus antes y después de la puesta. El ovario fue el organo que presentó un mayor descenso del contenido lipídico total (50,9%), que se transfirió a los huevos durante la oogénesis. En los diferentes organos estudiados, el contenido de lípidos polares fue superior al de lípidos neutros. Sin embargo, durante la puesta se transfirieron mayores cantidades de lípidos neutros que de polares tanto en el ovario como en el hepatopáncreas. El contenido de los ácidos grasos saturados de los lípidos totales del ovario disminuyó un 66,3%, el de monoinsaturados un 56,5% y el de los poliinsaturados un 62,6%. Acidos grasos como el 16:0, 16:1 n − 7 y 18:1 n − 9 contribuyeron de una forma importante a la compositión lipídica de los huevos. Mientras que el 20:5 n − 3 y el 22:6 n − 3 significaron un 4% y un 4,5% respectivamente de los lípidos totales del ovario que se aportaron a la puesta.