Coupled Na+ exit/Ca2+ entry (Na/Ca exchange operating in the Ca2+ influx mode) was studied in giant barnacle muscle cells by measuring 22Na+ efflux and 45Ca2+ influx in internally perfused, ATP-fueled cells in which the Na+ pump was poisoned by 0.1 mM ouabain. Internal free Ca2+, [Ca2+]i, was controlled with a Ca-EGTA buffering system containing 8 mM EGTA and varying amounts of Ca2+. Ca2+ seque...

In support of the on-going temporal palaeoenvironmental and palaeoclimatic reconstructions Neogene sediments, this study attempts describing palaeo-proxies recovered from DEL-1 Well, western offshore Niger Delta. The use standard smear slide method enabled recovery well-preserved calcareous nannofossils that depicts early to mid – Miocene (NN4 NN5) sediments. up-hole relationships between relat...

In tilapia exposed for 3 months to water of pH 4.5, prolactin cell activity, as estimated by ultrastructural morphometry and determination of prolactin synthesis in vitro, was significantly higher than in controls from neutral water. Sodium influx from the water was 50% lower than in the controls, indicating impaired branchial sodium uptake mechanisms. In contrast to predictions based on the re...

Recent studies of the fluxes of sodium and chloride across euryhaline teleost fish have shown that acclimation to fresh water involves a sharp reduction in the flux of both ions (Evans, 1967 c, 1969; Motais, 1967; Maetz et al. 1967 a, b; Potts & Evans, 1967; Ports et al. 1967). It has been shown, at least in Fundulus heteroclitus (Potts & Evans, 1967), Tilapia mossambica (Potts et al. 1967), Xi...

Potassium turnover was studied in rainbow trout, Salmo gairdneri Richardson, adapted to fresh water or 22 %o sea water using K and Rb. Potassium space of the whole body increased with time and was about 5 mmol kg" after 20h, while Rb space under the same conditions was only about 0-5 mmol kg", indicating slow penetration of body K by Rb + , especially in muscle and red blood cells. Potassium in...

Integumentary uptake of L-[(3)H]histidine by polychaete worms (Nereis succinea) from estuarine waters of Oahu, Hawaii was measured in the presence and absence of calcium and cadmium using a physiological saline that approximated the ion composition of 60 % sea water. In this medium 1 micromol L(-1) cadmium significantly increased (P<0.01) the uptake of 10 micromol L(-1)L-[(3)H]histidine, while ...

This study was formulated to investigate productivity systems within Kenyan territorial waters. The interaction of processes on the margins marine waters, particularly influx fresh water loaded with sediments and nutrients, influences coastal These deposited sediments, rich in create a topographic barrier northerly flowing East African Coastal Current (EACC). Phosphate nitrate peaks observed ar...

The biotic ligand model considers the biological and geochemical complexities that affect metal exposure. It relates toxicity to the fraction of physiological active sites impacted by reactive metal species. The biodynamic model is a complementary construct that predicts bioaccumulation and assumes that toxicity occurs when influx rates exceed rates of loss and detoxification. In this paper we ...