Is diet quality an overlooked mechanism for Bergmann's rule?

Bergmann's rule (body size increases with latitude) has long interested biologists; however, its mechanism remains unclear. An overlooked mechanism (latitudinal variation in plant quality) might help explain Bergmann's rule. We studied three herbivores.

Calcium translocations during the moulting cycle of the semiterrestrial isopod Ligia hawaiiensis (Oniscidea, Crustacea).

Terrestrial isopods moult first the posterior and then the anterior half of the body. During the moulting cycle they retain a significant fraction of cuticular calcium partly by storing it in sternal CaCO(3) deposits. We analysed the calcium content in whole Ligia hawaiiensis and the calcium distribution between the posterior, the anterior ventral, and the anterior dorsal cuticle during four stages of the moulting cycle.

Distribution of mycosporine-like amino acids in the sea hare Aplysia dactylomela: effect of diet on amounts and types sequestered over time in tissues and spawn.

We investigated the interaction of diet and accumulation of UV-absorbing mycosporine-like amino acids (MAAs) in body tissues and spawn of the sea hare Aplysia dactylomela to determine if MAA accumulation reflects type and level of dietary intake. Food sources were the red algae Acanthophora spicifera, Centroceras clavulatum, and Laurencia sp., and the green alga, Ulva lactuca.

Hemolymph ion composition and volume changes in the supralittoral isopod Ligia pallasii Brandt, during molt.

We analyzed ion composition and volume of the hemolymph of Ligia pallasii in four different stages of the molt cycle using capillary electrophoresis and 3H-inulin. The main ions in the hemolymph were Na+, K+, Mg2+ , Ca2+, and Cl-. The Ca2+ concentration increased significantly during the molt by 47% from intermolt to intramolt and by 37% from intermolt to postmolt, probably due to resorption of Ca2+ from the cuticle and sternal CaCO3 deposits.

Use of isolated digestive-gland cells in the study of biochemical and physiological processes in gastropod molluscs.

We describe a method for preparation and maintenance of isolated digestive-gland cells in the abalone, Haliotis kamtschatkana. Viability of the isolated cells was confirmed by the fact that 18 h after preparation the cells exhibited less than 5% staining with trypan blue and actively synthesized glycogen following the addition of glucose substrate. Use of the method in a 15-month study of metabolic activity of the digestive gland of H.