Cell-free translation of mRNA encoding an arterial smooth muscle cell proteoglycan core protein

The size and immunological reactivity of the primary gene products of a small non-aggregating dermatan sulfate proteoglycan from bovine and monkey arterial smooth muscle cells were examined after cell-free translation of mRNA. Antisera against the dermatan sulfate proteoglycans from bovine articular cartilage, DSPG II [Rosenberg et al. J. Biol. Chem. 260, 6304 (1985)] and human skin fibroblasts [Glossl et al. J. Biol. Chem. 259, 14144 (1984)] were used to show that the unmodified smooth muscle precursor core protein was immunologically related to both the cartilage and fibroblast core proteins. The size of the precursor core proteins within each species was identical regardless of the tissue source. Comparison of the precursor core proteins synthesized by primate and bovine cells revealed that the bovine core proteins were approximately 1500 Da larger than the primate core proteins as determined by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. A similar size difference was observed when the mature core proteins of monkey smooth muscle cells and bovine articular chondrocytes were compared after removal of the glycosaminoglycan chains. These results indicate that arterial smooth muscle cells synthesize a dermatan sulfate proteoglycan whose core protein is similar to, if not the same as, the cartilage and fibroblast dermatan sulfate proteoglycan core proteins. These core proteins may be encoded by the same gene that has diverged in size during speciation.     

Compartmentation of glutamate metabolism in brain. Evidence for the existence of two different tricarboxylic acid cycles in brain

1. (14)C from [1-(14)C]glucose injected intraperitoneally into mice is incorporated into glutamate, aspartate and glutamine in the brain to a much greater extent than (14)C from [2-(14)C]glucose. This difference for [1-(14)C]glucose and [2-(14)C]glucose increases with time. The amount of (14)C in C-1 of glutamate increases steadily with time with both precursors. It is suggested that a large part of the glutamate and aspartate pools in brain are in close contact with intermediates of a fast-turning tricarboxylic acid cycle. 2. (14)C from [1-(14)C]acetate and [2-(14)C]acetate is incorporated to a much larger extent into glutamine than into glutamate. An examination of the time-course of (14)C incorporated into glutamine and glutamate reveals that glutamine is not formed from the glutamate pool, labelled extensively by glucose, but from a small glutamate pool. This small glutamate pool is not derived from an intermediate of a fast-turning tricarboxylic acid cycle. 3. It is proposed that two different tricarboxylic acid cycles exist in brain.     

Natal dispersal in relation to population density and sex ratio in the field vole,Microtus agrestis

Summary In a sample of 240 juvenile field voles 8% of the males and 22% of the females reached sexual maturity within their natal home range. Among individuals retrapped as adults, 58% of males and 23% of females had dispersed, i.e. had moved more than one home range diameter. The mean distance moved for males (58.5 m) exceeded that for females (28.6 m). Male movement distances were negatively associated with total density, and with density of adult females, but not with male density. Female movements were not related to population density. There were no relation between sex ratio and distance moved. The distribution of distances moved for both males and females fit a geometrical distribution, suggesting the importance of competitive processes.     

Intraspecific brood parasitism: a strategy for floating females in the European starling

In many bird species, there is a floating population of females that are excluded from breeding because of competition for limited breeding resources. Female floaters may enhance their reproductive success by engaging in intraspecific brood parasitism. We studied female floaters in a population of European starlings, Sturnus vulgaris, in order to determine their identity and potential parasitic behaviour. Females were caught after being attracted to nestboxes with artificial nests during 1993-1995. None of the females was known to have a nest of her own at capture but 47% of the females either laid an egg in the nest or carried a fully developed egg within the reproductive tract, indicating that they were intraspecific brood parasites. The floating females were significantly younger and smaller than breeding females. Of 13 females equipped with radiotransmitters and followed daily, all but one started a breeding attempt of their own after 3-8 days and the majority settled as secondary females or mated with males where the original female had disappeared. This suggests that females that are unable to compete successfully for nest sites or males early in the breeding season may use intraspecific brood parasitism to enhance reproductive success during the period that they are constrained from breeding. The importance of settling rapidly because of a seasonal decline in reproductive success may also promote the evolution of intraspecific brood parasitism in the starling. The relative reproductive success of combining egg dumping with breeding compared with traditional breeding will depend on the costs of delaying breeding as well as the probability of finding a mate later in the breeding season. Copyright 1999 The Association for the Study of Animal Behaviour.     

Alterations in apoptosis and epithelial-mesenchymal transformation in an in vitro cleft palate model

The processes of apoptosis and epithelial-mesenchymal transformation have been identified as two major mechanisms by which secondary palatal shelves achieve fusion. The aim of this study was to investigate alterations in these mechanisms by changing the physical distance between paired palatal shelves in an in vitro model of palatogenesis. Wild-type palatal pairs were dissected from E13.5 CD1 mouse embryos and allowed to grow in tissue culture for 48 hours at various intershelf distances. During the fusion process, medial edge epithelial cell fate was assessed using terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) staining, to evaluate apoptosis, and carboxyfluorescence (carboxy-2,7'-dichlorofluorescein diacetate succinimidyl ester) labeling, to measure transformation to mesenchymal cells. Palatal pairs separated in culture greater than or equal to 0.4 mm failed to fuse. TUNEL staining showed that the number of apoptotic cells in the palatal shelves increased as the intershelf distance increased, becoming marked in shelves that did not achieve fusion. The amount of epithelial-mesenchymal transformation, however, decreased with increasing intershelf distance. These results suggest that the contribution of epithelial-mesenchymal transformation and apoptosis to palatal shelf development and fusion can be altered by physical proximity. Therefore, one mechanism behind clefting in utero may result from an imbalance in epithelial-mesenchymal transformation and apoptosis as observed in vitro where palatal shelves are challenged to fuse by physical separation. This effect could be significant in the understanding and treatment of developmental palatal abnormalities. Perhaps in utero manipulation of intershelf spacing or epithelial-mesenchymal transformation and/or apoptosis could reverse the clefting paradigm.     

Synthesis,radiolabeling and preliminary biological evaluation of radiolabeled 5-methyl-6-nitroquipazine,a potential radioligand for the serotonin transporter

5-Methyl-6-nitroquipazine, a novel analogue of the potent and selective serotonin transporter inhibitor 6-nitroquipazine was synthesized and radiolabeled with tritium and the positron emitter carbon-11. [³H]5-methyl-6-nitroquipazine was found to have a K_d=51±7 pM. The high affinity and the facile labeling of [¹¹C]5-methyl-6-nitroquipazine makes it a promising radioligand for visualization of the serotonin transporter with positron emission tomography.     

Synthesis and evaluation of 2-pyridylbenzothiazole, 2-pyridylbenzoxazole and 2-pyridylbenzofuran derivatives as 11C-PET imaging agents for β-amyloid plaques

The syntheses and SAR of new series of β-amyloid binding agents are reported. The effort to optimize signal-to-background ratios for these ligands are described. Compounds 8, 21 and 30 displayed desirable lipophilicity and pharmacokinetic properties. Compounds 8 and 21 were evaluated with in vitro autoradiographic studies and in vivo in APP/PS1 transgenic mice. It is shown that it was possible to increase the signal-to-background ratios compared to PIB 1, as demonstrated by compounds 8 and 21.