Patterns of colonization in a metapopulation of grey seals

The colonization of a new habitat is a fundamental process in metapopulation biology, but it is difficult to study. The emigration of colonists from established populations might be induced by resource competition owing to high local population density. Migration distances are also important because they determine the frequency and scale of recolonization and hence the spatial scale of the metapopulation. Traditionally, these factors have been investigated with demographic approaches that are labour-intensive and are only possible in amenable species. In many cases, genetic differentiation is minimal, preventing traditional genetic approaches from identifying the source of colonists unambiguously. Here we present a bayesian approach that integrates genetic, demographic and geographic distance data. We apply the method to study the British metapopulation of grey seals, which has been growing at 6% per year over the last few decades. Our method reveals differential recruitment to three newly founded colonies and implicates density-dependent dispersal in metapopulation dynamics by using genetic data.     

The effect of vitamin D3 and 25-hydroxycholecalciferol on intestinal transport of calcium in vivo and in vitro

Zusammenfassung 8 Stunden nach Injektion von 25-Hydroxycholecalciferol bei rachitischen Ratten steigerte sich der Kalzium-Transport des Duodenum in vivo wie auch in vitro bedeutend. Während dieser Zeit war Vitamin D₃, wirkungslos. 24 h nach der Injektion stimulierten beide Verbindungen in ähnlichem Masse den Kalzium-Transport.     

Neutral theory and relative species abundance in ecology

The theory of island biogeography asserts that an island or a local community approaches an equilibrium species richness as a result of the interplay between the immigration of species from the much larger metacommunity source area and local extinction of species on the island (local community). Hubbell generalized this neutral theory to explore the expected steady-state distribution of relative species abundance (RSA) in the local community under restricted immigration. Here we present a theoretical framework for the unified neutral theory of biodiversity and an analytical solution for the distribution of the RSA both in the metacommunity (Fisher's log series) and in the local community, where there are fewer rare species. Rare species are more extinction-prone, and once they go locally extinct, they take longer to re-immigrate than do common species. Contrary to recent assertions, we show that the analytical solution provides a better fit, with fewer free parameters, to the RSA distribution of tree species on Barro Colorado Island, Panama, than the lognormal distribution.     

Fraser syndrome and mouse blebbed phenotype caused by mutations in FRAS1/Fras1 encoding a putative extracellular matrix protein

Fraser syndrome (OMIM 219000) is a multisystem malformation usually comprising cryptophthalmos, syndactyly and renal defects. Here we report autozygosity mapping and show that the locus FS1 at chromosome 4q21 is associated with Fraser syndrome, although the condition is genetically heterogeneous. Mutation analysis identified five frameshift mutations in FRAS1, which encodes one member of a family of novel proteins related to an extracellular matrix (ECM) blastocoelar protein found in sea urchin. The FRAS1 protein contains a series of N-terminal cysteine-rich repeat motifs previously implicated in BMP metabolism, suggesting that it has a role in both structure and signal propagation in the ECM. It has been speculated that Fraser syndrome is a human equivalent of the blebbed phenotype in the mouse, which has been associated with mutations in at least five loci including bl. As mapping data were consistent with homology of FRAS1 and bl, we screened DNA from bl/bl mice and identified a premature termination of mouse Fras1. Thus, the bl mouse is a model for Fraser syndrome in humans, a disorder caused by disrupted epithelial integrity in utero.     

Relation between fibrinolytic activity and prostacyclin generation of atherosclerotic artery and dacron prosthetic graft

Summary The newly formed tissue of dacron vascular prosthetic grafts implanted in humans demonstrates prostacyclin generation and fibrinolytic activity comparable to that of the atherosclerotic artery in the vicinity. This provides some evidence that both activities important for haemostasis run parallel.     

The Fanconi anaemia gene FANCF encodes a novel protein with homology to ROM

Bardet-Biedl syndrome (BBS) is an autosomal recessive disorder with locus heterogeneity. None of the 'responsible' genes have previously been identified. Some BBS cases (approximately 10%) remain unassigned to the five previously mapped loci. McKusick-Kaufma syndrome (MKS) includes hydrometrocolpos, postaxial polydactyly and congenital heart disease, and is also inherited in an autosomal recessive manner. We ascertained 34 unrelated probands with classic features of BBS including retinitis pigmentosa (RP), obesity and polydactyly. The probands were from families unsuitable for linkage because of family size. We found MKKS mutations in four typical BBS probands (Table 1). The first is a 13-year-old Hispanic girl with severe RP, PAP, mental retardation and obesity (BMI >40). She was a compound heterozygote for a missense (1042GA, G52D) and a nonsense (1679TA, Y264stop) mutation in exon 3. Cloning and sequencing of the separate alleles confirmed that the mutations were present in trans. A second BBS proband (from Newfoundland), born to consanguineous parents, was homozygous for two deletions (1316delC and 1324-1326delGTA) in exon 3, predicting a frameshift. An affected brother was also homozygous for the deletions, whereas an unaffected sibling had two normal copies of MKKS. Both the proband and her affected brother had RP, PAP, mild mental retardation, morbid obesity (BMI >50 and 37, respectively), lobulated kidneys with prominent calyces and diabetes mellitus (diagnosed at ages 33 and 30, respectively). A deceased sister (DNA unavailable) had similar phenotypic features (RP with blindness by age 13, BMI >45, abnormal glucose tolerance test and IQ=64, vaginal atresia and syndactyly of both feet). Both parents and the maternal grandfather were heterozygous for the deletions. Genotyping with markers from the MKKS region confirmed homozygosity at 20p12 in both affected individuals.     

Critical relative indentation depth in carbon based thinfilms

The thin film hardness estimation by nanoindentation is influenced by substrate beyond a critical relative indentation depth(CRID). In this study we developed a methodology to identify the CRID in amorphous carbon film. Three types of amorphous carbon film deposited on silicon have been studied. The nanoindentation tests were carried out applying a 0.1–10 mN load range on a Berkovich diamond tip, leading to penetration depth-to-film thickness ratios of 8–100%. The work regained during unloading(We) and the work performed during loading(Wt) was estimated for each indentation. The trend of unload-to-load ratio(We/Wt) data as a function of depth has been studied. We/Wtdepth profiles showed a sigmoid trend and the data were fitted by means of a Hill sigmoid equation. Using Hill sigmoid fit and a simple analytical method it is possible to estimate CRID of carbon based films.     

平板式光生物反应器的Parietochloris incisa超高密度培养

利用平板式光生物反应器对一种新分离的微藻Parietochlorisincisa进行了室外放大培养研究。在最适培养条件下 ,实现了对该微藻的超高密度培养 ,使单位培养体积和单位培养面积的细胞生物量分别达到了 7.35g/ (L·d)和 96 .12 g/ (m2 ·d)