Impairment of endothelium-dependent arterial relaxation by lysolecithin in modified low-density lipoproteins

Atherosclerosis in animals and humans is associated with an unresponsiveness of arteries and arterioles to endothelium-dependent vasodilators--agents acting on smooth muscle indirectly by stimulating the release from endothelial cells of a vasodilator principle (endothelium-derived relaxing factor). Altered vasomotor regulation in atherosclerosis could partly reflect an injurious action of abnormal lipoproteins on endothelium. Recently, 'cell-modified' or 'oxidized' low-density lipoprotein (EC-LDL) has received increasing attention because of its potential cytotoxic and atherogenic properties. We report here that arteries exposed to EC-LDL in vitro show an endothelium-dependent vasoregulatory impairment closely resembling that of atherosclerotic arteries. Our results indicate that transfer of lysolecithin from EC-LDL to endothelial membranes produces a selective unresponsiveness to receptor-regulated endothelium-dependent vasodilators.     

Loss-of-function mutations in the cathepsin C gene result in periodontal disease and palmoplantar keratosis

Papillon-Lefèvre syndrome, or keratosis palmoplantaris with periodontopathia (PLS, MIM 245000), is an autosomal recessive disorder that is mainly ascertained by dentists because of the severe periodontitis that afflicts patients. Both the deciduous and permanent dentitions are affected, resulting in premature tooth loss. Palmoplantar keratosis, varying from mild psoriasiform scaly skin to overt hyperkeratosis, typically develops within the first three years of life. Keratosis also affects other sites such as elbows and knees. Most PLS patients display both periodontitis and hyperkeratosis. Some patients have only palmoplantar keratosis or periodontitis, and in rare individuals the periodontitis is mild and of late onset. The PLS locus has been mapped to chromosome 11q14-q21 (refs 7, 8, 9). Using homozygosity mapping in eight small consanguineous families, we have narrowed the candidate region to a 1.2-cM interval between D11S4082 and D11S931. The gene (CTSC) encoding the lysosomal protease cathepsin C (or dipeptidyl aminopeptidase I) lies within this interval. We defined the genomic structure of CTSC and found mutations in all eight families. In two of these families we used a functional assay to demonstrate an almost total loss of cathepsin C activity in PLS patients and reduced activity in obligate carriers.     

Energetic constraints on the diet of terrestrial carnivores

Species in the mammalian order Carnivora exhibit a huge diversity of life histories with body sizes spanning more than three orders of magnitude. Despite this diversity, most terrestrial carnivores can be classified as either feeding on invertebrates and small vertebrates or on large vertebrates. Small carnivores feed predominantly on invertebrates probably because they are a superabundant resource (sometimes 90% of animal biomass); however, intake rates of invertebrate feeders are low, about one tenth of those of vertebrate feeders. Although small carnivores can subsist on this diet because of low absolute energy requirements, invertebrate feeding appears to be unsustainable for larger carnivores. Here we show, by reviewing the most common live prey in carnivore diets, that there is a striking transition from feeding on small prey (less than half of predator mass) to large prey (near predator mass), occurring at predator masses of 21.5-25 kg. We test the hypothesis that this dichotomy is the consequence of mass-related energetic requirements and we determine the predicted maximum mass that an invertebrate diet can sustain. Using a simple energetic model and known invertebrate intake rates, we predict a maximum sustainable mass of 21.5 kg, which matches the point where predators shift from small to large prey.     

An arid-adapted middle Pleistocene vertebrate fauna from south-central Australia

How well the ecology, zoogeography and evolution of modern biotas is understood depends substantially on knowledge of the Pleistocene. Australia has one of the most distinctive, but least understood, Pleistocene faunas. Records from the western half of the continent are especially rare. Here we report on a diverse and exceptionally well preserved middle Pleistocene vertebrate assemblage from caves beneath the arid, treeless Nullarbor plain of south-central Australia. Many taxa are represented by whole skeletons, which together serve as a template for identifying fragmentary, hitherto indeterminate, remains collected previously from Pleistocene sites across southern Australia. A remarkable eight of the 23 Nullarbor kangaroos are new, including two tree-kangaroos. The diverse herbivore assemblage implies substantially greater floristic diversity than that of the modern shrub steppe, but all other faunal and stable-isotope data indicate that the climate was very similar to today. Because the 21 Nullarbor species that did not survive the Pleistocene were well adapted to dry conditions, climate change (specifically, increased aridity) is unlikely to have been significant in their extinction.     

近岸海漂垃圾自驱动收集装备的研制及应用

长期、有效地治理近岸海域海漂垃圾，解决人工收集近岸海漂垃圾效率低的问题，研制出以波浪能/太阳能为动力，由V字型浮围栏和垃圾收集系统两部分组成的近岸海漂垃圾自驱动收集装备。现场试验结果显示，布放此装置后，海滩海洋垃圾的单位面积数量由原来的每平方米053 个降为017 个，单位面积质量由37 g·m-2降为12 g·m-2，海滩环境质量由较差/差上升为中等。表明该装备可实现近岸海漂垃圾的自动、长期、有效治理。