Relationships within theRugopharynx delta species complex (Nematoda: Strongyloidea) from Australian marsupials inferred from allozyme electrophoretic data

Relationships between the strongyloid nematodesRugopharynx delta, R. zeta, R. omega, R. longibursaris, R. mawsonae andR. sigma, all from macropodid marsupials, were investigated using allozyme data. The phylogenetic trees derived from the electrophoretic data set were congruent with those of the hosts and were consistent with the hypothesis that the species complex originated in pademelons of the genusThylogale and diversified in rock-wallabies (Petrogale spp.) and scrub wallabies of the subgenusNotamacropus. Host switching is evident only between closely related macropodid taxa.     

Magnetic circular dichroism and electron paramagnetic resonance studies of hydrogenases I and II from Clostridium pasteurianum

The two iron-only hydrogenases (I and II) from Clostridium pasteurianum have been investigated by variable temperature magnetic circular dichroism (MCD) and electron paramagnetic resonance (EPR) spectroscopies. Samples were studied both reduced with dithionite under an atmosphere of H2 and after oxidation with thionine. The results are consistent with four and two [4Fe-4S]1+,2+ (F)-clusters in hydrogenases I and II, respectively. All four F-clusters are reduced and paramagnetic in reduced hydrogenase I, with up to one exhibiting an S = 3/2 ground state and the remainder having conventional S = 1/2 ground states. Both F-clusters have S = 1/2 ground states in reduced hydrogenase II; however, one appears to be only partially reduced under the conditions used for reduction. MCD studies of the oxidized enzymes show no temperature-dependent features in the visible region which can be attributed to the EPR-active S = 1/2 hydrogen-activating cluster, suggesting predominantly oxygen and nitrogen coordination for the iron atoms of this center. However, temperature-dependent MCD transitions arising from a hitherto undetected S greater than 1/2 Fe-S clusters are apparent in both oxidized hydrogenases. Detailed EPR studies of oxidized hydrogenase I revealed resonances from an S = 3/2 species, however, spin quantitation reveals this to be a trace component that is unlikely to be responsible for the observed low temperature MCD spectrum. The nature and origin of these S greater than 1/2 Fe-S clusters are discussed in light of the available spectroscopic data for these and other iron-only hydrogenases.     

The combined action of microwave radiation and hydrogen peroxide on the viability and ultrastructure of Pseudomonas aeruginosa cells

The comparative study of the action of microwave radiation and hydrogen peroxide, as well as their combined action, on the viability and ultrastructure of P. aeruginosa cells has been made. The combined use of microwave radiation and hydrogen peroxide has been shown to decrease the viability of P. aeruginosa 1.5-2 times in comparison with the isolated action of each factor. The electron microscopic study of the ultrastructure of cells have shown the deterioration of the surface structures, nuclear and ribosomal apparatus of the cells under the isolated action of each of the above-mentioned factors or under their combined action. The morphological picture of these changes has proved to be different. The maximum changes in the ultrastructure of P. aeruginosa cells have been registered after the combined action of these bactericidal factors.     

The Physical Aspects of the Primary Interaction of Therapeutic Ultrasound with Biological Tissue

Biophysics - The biophysical aspects of the effects of ultrasound on biological tissues are considered. A mathematical model that describes the effects of the primary interaction of mechanical...     

Body Size,Growth and Life Span: Implications for the Polewards Range Shift of Octopus tetricus in South-Eastern Australia

Understanding the response of any species to climate change can be challenging. However, in short-lived species the faster turnover of generations may facilitate the examination of responses associated with longer-term environmental change. Octopus tetricus, a commercially important species, has undergone a recent polewards range shift in the coastal waters of south-eastern Australia, thought to be associated with the southerly extension of the warm East Australian Current. At the cooler temperatures of a polewards distribution limit, growth of a species could be slower, potentially leading to a bigger body size and resulting in a slower population turnover, affecting population viability at the extreme of the distribution. Growth rates, body size, and life span of O. tetricus were examined at the leading edge of a polewards range shift in Tasmanian waters (40°S and 147°E) throughout 2011. Octopus tetricus had a relatively small body size and short lifespan of approximately 11 months that, despite cooler temperatures, would allow a high rate of population turnover and may facilitate the population increase necessary for successful establishment in the new extended area of the range. Temperature, food availability and gender appear to influence growth rate. Individuals that hatched during cooler and more productive conditions, but grew during warming conditions, exhibited faster growth rates and reached smaller body sizes than individuals that hatched into warmer waters but grew during cooling conditions. This study suggests that fast growth, small body size and associated rapid population turnover may facilitate the range shift of O. tetricus into Tasmanian waters.