The resistance of muscle larvae of Trichinella spiralis to exposure to low temperatures]

It has been shown that the resistance of muscular larvae of Trichinella spiralis to the effect of low temperatures depends on the conditions of freezing and composition of media possessing cryoprotective properties. It has been established that under optimal conditions (medium of microenvironment, conditions of freezing) during the storage in liquid nitrogen muscular larvae of T. spiralis preserve 50 to 60% of their resistance by the character of mobility and 11 to 15% by their capacity for reproduction. The question of creation of low-temperature bank for Trichinella is discussed.     

Phosphorylation of lactate dehydrogenase by purified plasma membranes of loach liver cells: stimulation with insulin

It is established that insulin enhances the ability of the loach liver plasma membranes to phosphorylate lactate dehydrogenase. In the case of insulin-treated plasma membranes the amount of incorporated 32P is more than 4 times higher than that of the basal level. It is concluded that insulin-stimulated plasma membrane-dependent phosphorylation of the enzyme is one of the possible molecular mechanisms of hormone action on intracellular metabolism.     

Salinity and waterlogging tolerance of some populations of Melaleuca ericifolia Smith

Seed germination of Melaleuca ericifolia (swamp paperbark) is delayed by submergence in water but the final percentage germination after removing seeds from water is unaffected; some seeds will germinate and the cotyledons emerge whilst submerged. Germination is totally inhibited at salinities of 14% and a population which naturally occurs adjacent to coastal saltmarsh was inhibited more by salinities of 6–12% than two other populations from freshwater habitats. Seedling growth may be increased by water-logging conditions and the degree of response differs for different seed sources. Inundation stimulates root growth and new roots are thick and aerenchymatous. Root systems in the field run horizontally and are shallow, apparently being restricted by clay at depth. All populations studied showed a similar seedling growth-response to salinity treatments; growth declined at salinities ≤ 13% and was severely restricted at 21%, although no seedlings died after 48 days’exposure to the latter treatment.     

Coupling between transmembrane calcium transport and membrane potential in retinal rod discs

Changes in the transmembrane potential of bovine rod discs were studied by use of the potential-sensitive fluorescence probes diS-C3-(5) and diBA-C4-(5). The disc membrane was shown to be impermeable to potassium ions. Their concentration in the disc is as high as 2.1 +/- 0.3 mM. The permeability of the disc membrane to Ca2+ was shown to be selective. The accumulation and release of Ca2+ were found to be accompanied by the generation of inside positive and inside negative transmembrane potentials, respectively. The uptake of Ca2+ in the discs may operate against the concentration gradient of the ion. The value of the potential developed is directly proportional to the logarithm of free Ca2+ concentration in the medium (delta phi m = 11.2 +/- 1.6 mV at 4.85 microM Ca2+fr). The accumulation of Ca2+ is decreased by sodium ions and totally inhibited by monensin. This indicates that a Na-Ca exchange process participates in Ca2+ uptake of photoreceptor discs.