环境对沼泽红假单胞菌基因型的影响

<正>紫色光合细菌是不产氧光合细菌的一个重要分支,包括紫色非硫细菌和紫色硫细菌。其中紫色非硫细菌具有极其丰富的代谢模式,可进行光能异养、光能自养和化能异养生长,其代谢的多样性使得它们广泛存活于不同的生态系统中,如土壤、湖泊、海洋及底泥等[1-2]。沼泽红假单胞菌(Rhodopseudomonas palustris)是紫     

Effects of lipoic acid on citrate content, aconitate hydratase activity, and oxidative status during myocardial ischemia in rats

The effects of lipoic acid on intensity of free radical reactions, citrate content, and aconitate hydratase during myocardial ischemia have been investigated. Treatment with lipoic acid normalized biochemiluminescence parameters and citrate level, which were increased in the myocardial pathology. Treatment with lipoic acid also increased specific activity of aconitate hydratase, which was decreased in myocardium and blood of animals with myocardial ischemia. Administration of lipoic acid decreased DNA fragmentation observed during myocardial ischemia. The data suggest that lipoic acid can be effectively used as a cardioprotector preventing the development of free radical oxidation during myocardial ischemia.     

Genetic and morphological differentiation of the mangrove crab Perisesarma guttatum (Brachyura: Sesarmidae) along an East African latitudinal gradient

The genetic structure and morphometric differentiation of mangrove crab Perisesarma guttatum populations were examined among shelf connected locations along a latitudinal gradient on the East African coast. Over 2200 specimens were sampled from 23 mangrove sites for geometric morphometrics analysis. Population genetic analyses of mitochondrial cytochrome c oxidase subunit I (COI) DNA sequences were used to evaluate connectivity among populations. A total of 73 haplotypes were detected, and almost no haplotypes were found in common between two highly supported phylogeographic clades: southern Mozambique (Inhaca Island and Maputo Bay) and a northern clade that included north Mozambique, Tanzania and Kenya. These two clades were identified based on the species' populations pairwise genetic differentiation and geographical location. Φ_ST values were considerably high between the two clades, indicating the presence of significant population genetic structure between Kenya and South Mozambique. However, each clade was composed of genetically similar populations along the latitudinal gradient, and no significant population structure was found within each clade because the Φ_st values were not significant. The morphometric analysis corroborated the division into two clades (i.e. Inhaca Island/Maputo Bay and northern populations) and also detected less shape variation among populations that were few kilometres apart. The significant spatial genetic structuring between the southern and the northern populations of P. guttatum along the geographic gradient under study, combined with morphological differences, suggests that these populations may be considered as cryptic species. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99 , 28–46.     

The effects of flock size and human presence on vigilance and feeding behavior in the Eurasian Coot (<Emphasis Type="Italic">Fulica atra</Emphasis> L.) during breeding season

Group size influences individual vigilance in different bird species. Most studies have shown that animals spend more time for feeding and less time on vigilance when in groups. Apart from group size, additional factors, such as group density, age, sex, and season, are considered to influence vigilance behaviors. The aim of the present study was to investigate the effects of flock size and human presence on vigilance and feeding in the Eurasian Coot (Fulica atra) during the breeding season. This work was performed in Yorukkirka Lake (Eskisehir, Turkey) from March to August 2005. No correlation was found between flock size and vigilance rates during either human absence or presence. On the other hand, when comparing behavioral differences between human presence and absence, humans appeared to have an important negative effect on vigilance rates, vigilance duration, and feeding behavior, regardless of flock size.     

Individual variation in migratory movements and winter behaviour of Iberian Lesser Kestrels Falco naumanni revealed by geolocators

The population decline of the Lesser Kestrel Falco naumanni has been the subject of studies across its Western Palaearctic breeding range, but little is known about its use of pre‐migratory areas or African wintering quarters. We used geolocators to describe the temporal and spatial patterns of Portuguese Lesser Kestrel migration and wintering behaviour. Data on the complete migration were obtained from four individuals and another three provided further information. Prior to southward migration, Lesser Kestrels showed two different behaviours: northward‐orientated movements to Spain and movements in the proximity of the breeding area. Autumn migration took place mostly in late September; spring departures occurred mainly in the first half of February. Wintering grounds included Senegal, Mauritania and Mali, with individuals overlapping considerably in Senegal. Movements registered within the wintering grounds suggest itinerant behaviour in relation to local flushes of prey. During spring migration, birds crossed the Sahara Desert through Mauritania, Western Sahara and Morocco before passing over the Mediterranean to reach Portugal. Autumn migration lasted 4.8 ± 1.1 days, and spring migration lasted 4.1 ± 0.3 days. The mean daily flight range varied between approximately 300 and 850 km for an entire journey of around 2500 km. Effective protection of roosting sites in both pre‐migratory and wintering areas and maintaining grasshopper populations in Sahelian wintering quarters appear crucial in preserving this threatened migratory raptor across its African–Eurasian flyway. There was no evidence of any deleterious effects of fitting birds with loggers.     

Isolation and characterization of polymorphic microsatellite markers for the endangered Korean freshwater fish Hemibarbus mylodon

Korean barbel, Hemibarbus mylodon, is an endangered freshwater species endemic to Korea. In order to undertake a conservation program for this species in Korea, it is essential to evaluate its genetic diversity and population structure. For this purpose, we developed 10 polymorphic microsatellite markers and examined their allelic variation using a total of 60 wild individuals collected from three different localities. The number of alleles per locus ranged from three to 26. The expected and observed heterozygosities per locus ranged from 0.19 to 0.94 and from 0.20 to 0.98, respectively. Significant departures from Hardy–Weinberg equilibrium expectations occurred in four loci. These markers will be useful for the assessment of genetic diversity for this species.     

p130Cas Couples the tyrosine kinase Bmx/Etk with regulation of the actin cytoskeleton and cell migration

Bmx/Etk, a member of the Tec/Btk family of nonreceptor kinases, has recently been shown to mediate cell motility in signaling pathways that become activated upon integrin-mediated cell adhesion (Chen, R., Kim, O., Li, M., Xiong, X., Guan, J. L., Kung, H. J., Chen, H., Shimizu, Y., and Qiu, Y. (2001) Nat Cell Biol. 3, 439-444). The molecular mechanisms of Bmx-induced cell motility have so far remained unknown. Previous studies by us and others have demonstrated that a complex formation between the docking protein p130Cas (Cas) and the adapter protein Crk is instrumental in connecting several stimuli to the regulation of actin cytoskeleton and cell motility. We demonstrate here that expression of Bmx leads to an interaction between Bmx and Cas at membrane ruffles, which are sites of active actin remodeling in motile cells. Expression of Bmx also enhances tyrosine phosphorylation of Cas and Cas.Crk complex formation, and coexpression of Bmx with Cas results in an enhanced membrane ruffling and haptotactic cell migration. Importantly, a mutant form of Bmx that fails to interact with Cas also fails to induce cell migration. Furthermore, expression of a dominant-negative form of Cas that is incapable of interacting with Crk inhibits Bmx-induced membrane ruffling and cell migration. These studies suggest that Bmx-Cas interaction, phosphorylation of Cas by Bmx, and subsequent Cas.Crk complex formation functionally couple Bmx to the regulation of actin cytoskeleton and cell motility.     

Dual origin of avian lymphatics

The earliest signs of the lymphatic vascular system are the lymph sacs, which develop adjacent to specific embryonic veins. It has been suggested that sprouts from the lymph sacs form the complete lymphatic vascular system. We have studied the origin of the jugular lymph sacs (JLS), the dermal lymphatics and the lymph hearts of avian embryos. In day 6.5 embryos, the JLS is an endothelial-lined sinusoidal structure. The lymphatic endothelial cells (LECs) stain (in the quail) positive for QH1 antibody and soybean agglutinin. As early as day 4, the anlagen of the JLS can be recognized by their Prox1 expression. Prox1 is found in the jugular section of the cardinal veins, and in scattered cells located in the dermatomes along the cranio-caudal axis and in the splanchnopleura. In the quail, such cells are positive for Prox1 and QH1. In the jugular region, the veins co-express the angiopoietin receptor Tie2. Quail-chick-chimera studies show that the peripheral parts of the JLS form by integration of cells from the paraxial mesoderm. Intra-venous application of DiI-conjugated acetylated low-density lipoprotein into day 4 embryos suggests a venous origin of the deep parts of the JLS. Superficial lymphatics are directly derived from the dermatomes, as shown by dermatome grafting. The lymph hearts in the lumbo-sacral region develop from a plexus of Prox1-positive lymphatic capillaries. Both LECs and muscle cells of the lymph hearts are of somitic origin. In sum, avian lymphatics are of dual origin. The deep parts of the lymph sacs are derived from adjacent veins, the superficial parts of the JLS and the dermal lymphatics from local lymphangioblasts.     

Higher temperature reduces the effects of litter quality on decomposition by aquatic fungi

1. We investigated the effects of riparian plant diversity (species number and identity) and temperature on microbially mediated leaf decomposition by assessing fungal biodiversity, fungal reproduction and leaf mass loss. 2. Leaves of five riparian plant species were first immersed in a stream to allow microbial colonisation and were then exposed, alone or in all possible combinations, at 16 or 24 °C in laboratory microcosms. 3. Fungal biodiversity was reduced by temperature but was not affected by litter diversity. Temperature altered fungal community composition with species of warmer climate, such as Lunulospora curvula, becoming dominant. 4. Fungal reproduction was affected by litter diversity, but not by temperature. Fungal reproduction in leaf mixtures did not differ or was lower than that expected from the weighted sum of fungal sporulation on individual leaf species. At the higher temperature, the negative effect of litter diversity on fungal reproduction decreased with the number of leaf species. 5. Leaf mass loss was affected by the identity of leaf mixtures (i.e. litter quality), but not by leaf species number. This was mainly explained by the negative correlation between leaf decomposition and initial lignin concentration of leaves. 6. At 24 °C, the negative effects of lignin on microbially mediated leaf decomposition diminished, suggesting that higher temperatures may weaken the effects of litter quality on plant litter decomposition in streams. 7. The reduction in the negative effects of lignin at the higher temperature resulted in an increased microbially mediated litter decomposition, which may favour invertebrate‐mediated litter decomposition leading to a depletion of litter stocks in streams.     

内源性NO在LPS和TNFα诱导离体兔肺动脉反应性变化中 …

目的：探讨脂多糖（Ｌｉｐｏｐｏｌｙｓａｃｃｈａｒｉｄｅ,ＬＰＳ）和肿瘤坏死因子α（ｔｕｍｏｒ ｎｅｃｒｏｓｉｓ ｆａｃｔｏｒ ａｌｐｈａ,ＴＮＦα）所致离体肺动脉反应性张力变化与肺动脉源性一氧化氮（ｎｉｔｒｉｃ ｏｘｉｅ,ＮＯ）的关系。方法：离体兔肺动脉环用ＬＰＳ＋ＴＮＦα、ＬＰＳ或深剂孵育２ｈ和６ｈ,检测肺动脉对乙酰胆碱（ＡＣｈ）、硝普钠（ＳＮＰ）和苯肾上腺素（ＰＥ）的累积剂量反应,以及一氧化氮