Oxygen consumption by the bivalve Donax vittatus (da Costa)

The acute oxygen consumption of Donax vittatus (da Costa) freshly collected at different times from a beach at Barrassie, Ayrshire, Scotland, has been measured at different temperatures. The logarithmic relationship between oxygen consumption and body weight showed a significant difference on only one occasion, and a common regression coefficient (b) of 0.865 could be used for regressions of oxygen consumption on weight. Over the temperature range 2.9–20 °C oxygen consumption rose with temperature. There was a linear decline of Q₁₀ with temperature in the range 2.9 –20 °C. Differences in values of the constant (a) in the regression equation suggest that there is some acclimation to temperature, resulting in rotation of the rate/temperature curve counterclockwise for warm-acclimated animals, and a reduction of Q₁₀ in cold-acclimated animals. The differences in oxygen consumption which result are small and appear to have little practical significance. High levels of metabolically-inactive materials such as stored glycogen reserves lead to a reduction in the weight-specific oxygen consumption. Spawning animals show an increased oxygen consumption.     

Characterization of the drug retention and pharmacokinetic properties of liposomal nanoparticles containing dihydrosphingomyelin

The drug retention and circulation lifetime properties of liposomal nanoparticles (LN) containing dihydrosphingomyelin (DHSM) have been investigated. It is shown that replacement of egg sphingomyelin (ESM) by DHSM in sphingomyelin/cholesterol (Chol) (55/45; mol/mol) LN results in substantially improved drug retention properties both in vitro and in vivo. In the case of liposomal formulations of vincristine, for example, the half-times for drug release (T(1/2)) were approximately 3-fold longer for DHSM/Chol LN as compared to ESM/Chol LN, both in vitro and in vivo. Further increases in T(1/2) could be achieved by increasing the drug-to-lipid ratio of the liposomal vincristine formulations. In addition, DHSM/Chol LN also exhibit improved circulation lifetimes in vivo as compared to ESM/Chol LN. For example, the half-time for LN clearance (Tc(1/2)) at a low lipid dose (15 micromol lipid/kg, corresponding to 8 mg lipid/kg body weight) in mice was 3.8 h for ESM/Chol LN compared to 6 h for DHSM/Chol LN. In addition, it is also shown that DHSM/Chol LN exhibit much longer half-times for vincristine release as compared to LN with the "Stealth" lipid composition. It is anticipated that DHSM/Chol LN will prove useful as drug delivery vehicles due to their excellent drug retention and circulation lifetime properties.     

Identification of protease 3.4.24.11 as the major atrial natriuretic factor degrading enzyme in the rat kidney

We have identified a metalloendoprotease from rat kidney cortex that cleaves the cysteine-phenylalanine bond (Cys7-Phe8) within the 17 amino acid ring structure of atrial natriuretic factor (ANF). Cleavage at this site represents the major ANF degradative activity in rat kidney, and is inhibited by the known metalloendoprotease inhibitors, thiorphan, phosphoramidon and zincov with IC50 values in the nanomolar range. Since these are specific inhibitors of protease 3.4.24.11, both protease 3.4.24.11 and ANF degrading activities were monitored during purification. Both activities copurified at each chromatographic step. Furthermore, purified protease 3.4.24.11 cleaved ANF specifically at the Cys7-Phe8 bond. It is concluded from this work that the major ANF degrading enzyme in rat kidney is protease 3.4.24.11.     

Altered lipoprotein metabolism in chronic inflammatory states: proinflammatory high-density lipoprotein and accelerated atherosclerosis in systemic lupus erythematosus and rheumatoid arthritis

In this review, the authors discuss the formation and structure of high-density lipoproteins (HDLs) and how those particles are altered in inflammatory or stress states to lose their capacity for reverse cholesterol transport and for antioxidant activity. In addition, abnormal HDLs can become proinflammatory (piHDLs) and actually contribute to oxidative damage. The assay by which piHDLs are identified involves studying the ability of test HDLs to prevent oxidation of low-density lipoproteins. Finally, the authors discuss the potential role of piHDLs (found in some 45% of patients with systemic lupus erythematosus and 20% of patients with rheumatoid arthritis) in the accelerated atherosclerosis associated with some chronic rheumatic diseases.     

Rehabilitation of Logged Rain Forests: Avifaunal Composition,Habitat Structure,and Implications for Biodiversity‐Friendly REDD+

The inclusion of carbon stock enhancements under the Reducing Emissions from Deforestation and Forest Degradation (REDD+) framework will likely drive a rapid increase in biosequestration projects that remove carbon from the atmosphere through rehabilitation of degraded primary rain forests. Such projects could also present an important opportunity to reverse losses of biodiversity from degraded rain forests, but concern has recently been expressed that management interventions to increase carbon stocks may conflict with biodiversity conservation. Focusing on a large‐scale rain forest rehabilitation project in northern Borneo, we examine: (i) how intensive rehabilitation of selectively logged forests affected patterns of bird community composition and (ii) whether changes in vegetation structure explain observed shifts in avian guild structure and species composition. Bird composition differed between unlogged, naturally regenerating logged, and rehabilitated logged habitats, with the avifauna of rehabilitated forest more similar to that of naturally regenerating forest. Crucially, rehabilitation did not adversely affect either those species that declined after logging or those species that are IUCN Red Listed. Rehabilitation reduced the prevalence of vines and shrubs within regenerating forest, and across all habitats, the abundance and species richness of all birds and of obligate frugivores were positively related to vine prevalence. In contrast, the abundance and richness of frugivore–insectivore generalists and of salliers were negatively related to vines, suggesting that avifaunal responses to forest rehabilitation were attributable to liberation cutting of vines. Management intervention to increase carbon stocks had little adverse effect on avian biodiversity and we therefore argue that rain forest rehabilitation should play a strong role in future REDD+ agreements.     

Plasmalogenase activity in normal and demyelinating tissue of the central nervous system

1. The plasmalogenase activity of brain was found to be associated with the white matter but was absent from myelin fractions. 2. Increased enzyme activity was found in demyelinating spinal cords from vitamin B₁₂-deficient monkeys and in white matter from a patient with multiple sclerosis.     

Hybridization and speciation

Hybridization has many and varied impacts on the process of speciation. Hybridization may slow or reverse differentiation by allowing gene flow and recombination. It may accelerate speciation via adaptive introgression or cause near‐instantaneous speciation by allopolyploidization. It may have multiple effects at different stages and in different spatial contexts within a single speciation event. We offer a perspective on the context and evolutionary significance of hybridization during speciation, highlighting issues of current interest and debate. In secondary contact zones, it is uncertain if barriers to gene flow will be strengthened or broken down due to recombination and gene flow. Theory and empirical evidence suggest the latter is more likely, except within and around strongly selected genomic regions. Hybridization may contribute to speciation through the formation of new hybrid taxa, whereas introgression of a few loci may promote adaptive divergence and so facilitate speciation. Gene regulatory networks, epigenetic effects and the evolution of selfish genetic material in the genome suggest that the Dobzhansky–Muller model of hybrid incompatibilities requires a broader interpretation. Finally, although the incidence of reinforcement remains uncertain, this and other interactions in areas of sympatry may have knock‐on effects on speciation both within and outside regions of hybridization.     

Further evidence for the importance of parental source of the Xce allele in X chromosome inactivation

Using mice that were mosaics for both Xce and phosphoglycerate kinase (Pgk-1) alleles, we present further evidence that the parental source of the X chromosome may affect the probability of that X chromosome remaining active. The reciprocal cross differences in PGK-1 activity described here are intermediate between those published previously for other alleles of Xce.