Physiology of the Apple Snail Pomacea maculata: Aestivation and Overland Dispersal.

Apple snails, in the genus Pomacea, have gained considerable notoriety for their impact on invaded habitats. Louisiana is currently under invasion by Pomacea maculata, which represents a potential threat to the state's valuable plants and cash crops. Insight into the physiology of the invasive snail may assist in developing control measures and enhance our understanding of the processes of adaptation and coevolution that accompany introductions.

Modulation of pumping rate by two species of marine bivalve molluscs in response to neurotransmitters: Comparison of in vitro and in vivo results.

Most studies regarding the neuroanatomy and neurophysiology of molluscan ctenidia have focused on isolated ctenidial tissue preparations. This study investigated how bivalve molluscs modulate their feeding rates by examining the effects of a variety of neurotransmitters, including serotonin, dopamine, and the dopamine agonist apomorphine on both isolated ctenidial tissue and in intact members of two commercially important bivalve species: the blue mussel, Mytilus edulis; and the bay scallop Argopecten irradians. In particular, we examined the effect of changes in: 1) beat of the lateral cilia (in vitro), 2) distance between ctenidial filaments and/or plicae (in vivo), and 3) diameter of the siphonal openings (in vivo) on alteration of bulk water flow through the mantle cavity.

Osmoregulation and excretion.

The article discusses advances in osmoregulation and excretion with emphasis on how multicellular animals in different osmotic environments regulate their milieu intérieur. Mechanisms of energy transformations in animal osmoregulation are dealt with in biophysical terms with respect to water and ion exchange across biological membranes and coupling of ion and water fluxes across epithelia. The discussion of functions is based on a comparative approach analyzing mechanisms that have evolved in different taxonomic groups at biochemical, cellular and tissue levels and their integration in maintaining whole body water and ion homeostasis.

Effects of copper on osmoregulation in sheepshead minnow, Cyprinodon variegatus acclimated to different salinities.

The sheepshead minnow, Cyprinodon variegatus is a euryhaline fish that inhabits estuaries and coastal marshes where it encounters a wide range of salinities. Many of these areas also have elevated levels of contaminants, creating the potential for toxic ions to interfere with the uptake of ions for osmoregulation. To determine whether the effect of copper on osmoregulatory activity is dependent on the osmotic conditions that individuals have been living at, fish were acclimated for 14 days to 2.

EPITHELIAL WATER PERMEABILITY IN THE EURYHALINE MUSSEL GEUKENSIA DEMISSA: DECREASE IN RESPONSE TO HYPOOSMOTIC MEDIA AND HORMONAL MODULATION.

The diffusional water permeability of isolated mantles from the mussel Geukensia demissa was reduced by incubation ofthe tissues in hypoosmotie media. The permeability of mantles from 1000 mOsm seawater (SW)-accimated animals was 6 x 10 cm/s. A four-hour incubation in 500 mOsm SW or 250 mOsm SW reduced the water permeability by 2 x l0 cm/s and 4 x 10 cm/s, respectively.