Linkages between seagrass,mangrove and saltmarsh as fish habitat in the Botany Bay estuary,New South Wales

Shallow-water vegetated estuarine habitats, notably seagrass, mangrove and saltmarsh, are known to be important habitats for many species of small or juvenile fish in temperate Australia. However, the movement of fish between these habitats is poorly understood, and yet critical to the management of the estuarine fisheries resource. We installed a series of buoyant pop nets in adjacent stands of seagrass, mangrove and saltmarsh in order to determine how relative abundance of fishes varied through lunar cycles. Nets were released in all habitats at the peak of the monthly spring tide for 12 months, and in the seagrass habitat at the peak of the neap tide also. The assemblage of fish in each habitat differed during the spring tides. The seagrass assemblage differed between spring and neap tide, with the neap tide assemblage showing greater abundances of fish, particularly those species which visited the adjacent habitats when inundated during spring tides. The result supports the hypothesis that fish move from the seagrass to the adjacent mangrove and saltmarsh during spring tides, taking advantage of high abundances of zooplankton, and use seagrass as a refuge during lower tides. The restoration and preservation of mangrove and saltmarsh utility as fish habitat may in some situations be linked to the proximity of available seagrass.     

High resolution scanning electron micrographic study of dissociated mouse taste cells

New techniques for enzymatic dissociation of mammalian tastecells allowed us to study, for the first time, the morphologyof murine taste receptor cells using high resolution scanningelectron microscopy. Cell shape varied from spindle to bipolarto lamellar, similar to shapes previously described in cellsfrom amphibian taste buds. Cell length varied from 19 to 65µm (39 ± 19 µm), with width averaging 6 ±3.4 µm. A rare picture of the apical microvilli of a tastereceptor cell, and a view of microvilli within a taste pore,suggest that at any given time, five to eight taste cells maybe exposed to the oral cavity. Assuming a cell life-span of10 days, and 50 cells per bud, all of which eventually reachthe taste pore, one can calculate that the average cell is exposedto the oral environment for     

Mechanism of stabilization of synaptosomes with alpha-tocopherol during exposure to phospholipase A2

Changes in potential-dependent fluorescence were studied, using fluorescent probe di-S-C3-(5), in synaptosome suspensions exposed to phospholipase A2, alpha-tocopherol and its derivatives. Phospholipase A2 increased potential-dependent fluorescence, i.e. depolarization of synaptosome membranes. The damaging phospholipase A2 effect was prevented and/or abolished by alpha-tocopherol added to synaptosome suspensions before and after phospholipase A2. Alpha-tocopherol derivatives (2,2,5,7,8-pentamethyl-6-hydroxychromane and alpha-tocopheryl-acetate as well as 4-methyl-2,6-di-tert-butylphenol) failed to exert a protective effect on synaptosome membranes modified by phospholipase A2. It is suggested that alpha-tocopherol effect is determined by its interaction with fatty acids, with 6-hydroxy groups of chromanol nucleus and phytol chain being essential for the complex formation.     

Phospholipid oxidation catalyzed by cytochrome c in liposomes

Oxidation of liposome phospholipids has been studied in the presence of cytochrome c. Sonicated vesicles of soya bean or egg-yolk lipids, or purified phospholipid preparations, were treated with oxidized cytochrome c at a 10:4 lipid/protein ratio (w/w). Lipid peroxidation was examined by oxygen polarography, gas-liquid chromatography (GLC) and the thiobarbituric acid test. Oxidized, but not reduced, cytochrome effectively catalyzes lipid oxidation under these conditions. Oxygen consumption and disappearance of unsaturated fatty acids follow closely similar patterns, the O2 consumption rate showing a maximum (1.53 mol O2/min per mol heme) shortly before fatty acid loss reaches its peak. GLC and O2 consumption data suggest that monohydroperoxides are the most abundant oxidized species in the system. The thiobarbituric acid reaction, however, appears only to be of qualitative value in peroxidation studies. In order to test the mechanism through which oxidation occurs in our system, the effect of liposome composition and the presence of antioxidants was tested, both on cytochrome c binding to bilayers and on O2 consumption. Oxidized and reduced cytochrome c bind the lipid bilayers with similar affinity, but only the oxidized form is active in autoxidation. Antioxidants do not modify either cytochrome c binding to sonicated liposomes. Lipid composition does influence considerably cytochrome binding, and O2 consumption is correspondingly altered. Studies with various antioxidants and inhibitors suggest that both free radicals and singlet oxygen may be involved in the process under study.     

A note on a modified membrane-Bovis agar for the enumeration of Streptococcus bovis by membrane filtration

The effect of dilution and temperature on the antibacterial properties of potassium sorbate was determined. The time taken to kill a standard inoculum of Escherichia coli was increased considerably after either dilution of the preservative or lowering of the temperature. The value for the concentration exponent, eta, was approximately 3 and that for the temperature coefficient, Q10, was 2.3.