Protein inhibitor of ornithine decarboxylase does not account for effect of putrescine on 3T3 cells

Putrescine and other amines are known to rapidly reduce or prevent increases in ornithine decarboxylase activity in a number of systems. We have confirmed reports of a nondialyzable inhibitor of the enzyme in serum-starved H-35 hepatoma cells exposed to serum and putrescine. In contrast, we detected little if any nondialyzable inhibitor in serum-limited Swiss 3T3 cells treated similarly. Also, evidence of a dissociable enzyme-inhibitor complex was found in H-35 cells but not in 3T3 cells. These results suggest that assimilated putrescine can reduce ornithine decarboxylase activity by mechanisms not involving a macromolecular inhibitor.     

Ca2+ transport and permeability in inside-out red cell membrane vesicles after freezing

To evaluate the effects of freezing and thawing on Ca2+ transport and permeability, inside-out red cell membrane vesicles (IORCMV) are examined. Exposure to the cryoprotectant Me2SO as well as different cooling regimes on unprotected and cryoprotected vesicles do not affect the membrane Ca2+ transport. However, freezing and thawing increase the membrane permeability to sucrose.     

The Histone Variant His2Av is Required for Adult Stem Cell Maintenance in the Drosophila Testis

Many tissues are sustained by adult stem cells, which replace lost cells by differentiation and maintain their own population through self-renewal. The mechanisms through which adult stem cells maintain their identity are thus important for tissue homeostasis and repair throughout life. Here, we show that a histone variant, His2Av, is required cell autonomously for maintenance of germline and cyst stem cells in the Drosophila testis. The ATP-dependent chromatin-remodeling factor Domino is also required in this tissue for adult stem cell maintenance possibly by regulating the incorporation of His2Av into chromatin. Interestingly, although expression of His2Av was ubiquitous, its function was dispensable for germline and cyst cell differentiation, suggesting a specific role for this non-canonical histone in maintaining the stem cell state in these lineages.     

Changes in the breeding wader populations of the machair of the Western Isles,Scotland, between 2000 and 2007

Capsule The machair of the Uists continues to support one of the most important assemblages of breeding waders in Europe, but there have been major variations in population change across the archipelago, the causes of which are poorly understood.     

Winter bird communities in forest plantations in western England and their response to vegetation,growth stage and grazing

This paper presents the results of a study of wintering bird communities across a wide range of coniferous, broadleaved and mixed forest stands in the Forest of Dean, western England. Bird communities of broadleaved and coniferous woodland differed with respect to their species composition. The mean number of individual birds recorded increased linearly with woodland age and was not influenced by woodland type, stand size or the presence of grazing. Woodland age and type and the presence or absence of grazing all significantly influenced bird species richness and the proportions of the bird community made up by granivores, insectivores and omnivores. Broadleaved stands held more species than coniferous stands. Ungrazed stands held significantly more species, particularly seed-eating species, than grazed stands and this effect was independent of woodland type. Ordination was used to relate variation in tree species composition and stand structure to bird community composition. A larger number of species was associated with broadleaved stands and stands with abundant undergrowth than was associated with coniferous stands or stands with little undergrowth. Woodland age had less effect on bird community composition than the extent of undergrowth and the conifer to broadleaf ratio. The results of this work have relevance to the enhancement of winter bird communities in commercial forests.     

Conformational studies of peptides. The crystal structures of N-acetyl-L-prolinamide and N-acetyl-(S)-thiazolidine-4-carboxamide

The crystal structure of N′-acetyl-L -prolinamide and its isomorphous alalog N′-acetyl-(S)-thiazolidine-4-carboxamide was determined using highly accurate parameters obtained by room- and low-temperature data-collecting systems. Both crystals are orthorhombic, space group P2₁2₁2₁, with four molecules per unit cell held together by a hydrogen-bond system that extends in all directions. Both molecules exhibit the following conformational features: the acetyl group is in the trans configuration in respect to the tertiary amide. The primary amide is almost at right angles with respect to the mean plane of the ring and the –NH₂ group is over the ring. The pyrrolidine and thiazolidine rings were found to be rather flexible with C^β puckering in the former and sulfur in the latter.