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991.
PAULO M. BRITO FRANÇOIS J. MEUNIER GAEL CLÉMENT DIDIER GEFFARD‐KURIYAMA 《Palaeontology》2010,53(6):1281-1290
Abstract: The palaeohistological study of the calcified internal organ of Axelrodichthys araripensis Maisey, 1986, a coelacanthiform from the Lower Cretaceous of Brazil (Crato (Aptian) and Santana (Albian) formations of the Araripe Basin), shows that the walls of this organ consist of osseous blades of variable thickness separated from each other by the matrix. This indicates that, in the living individuals, the walls were reinforced by ossified plates, probably separated by conjunctive tissue. This calcified sheath present in Axelrodichthys, as well as in other fossil coelacanths, lies in ventral position relative to the gut and its single anterior opening is located under the opercle, suggesting a direct connection with the pharynx or the oesophagus. The calcified organ of Axelrodichthys, like that of other fossil coelacanths, is here regarded as an ‘ossified lung’ and compared with the ‘fatty lung’ of the extant coelacanth Latimeria. The reinforcement of the pulmonary walls by the overlying osseous blades could be interpreted as a means of adapting volumetric changes in the manner of bellows, a necessary function for ventilation in pulmonary respiration. Other functional hypotheses such as hydrostatic and/or acoustic functions are also discussed. 相似文献
992.
胡椒碱及其衍生物对SH-SY5Y细胞的保护作用研究 总被引:1,自引:0,他引:1
对胡椒碱进行结构改造,合成了4个胡椒碱衍生物。以高浓度皮质酮(corticosterone)模拟抑郁及焦虑症神经细胞损伤状态。对包括胡椒碱在内的5个化合物进行了SH-SY5Y细胞保护作用的研究。结果表明:胡椒碱、5-(3,4-methylenedioxy phenyl)-2E,4E-pentadienoic acid n-propylamine amide(2)以及5-(3,4-methylenedioxyphenyl)-2E,4E-pentadienoic acid N-methyl piperazine amide(4)对SH-SY5Y细胞有较好的保护作用。其中化合物2对SH-SY5Y细胞具有明显和持久的保护作用。 相似文献
993.
宠物鸟种类多,来源地广,检验检疫预防措施缺乏,致使宠物鸟疫病不断传播,并造成人类的感染,已经威胁到公共卫生。宠物鸟疫病中以新城疫、禽流感、鹦鹉热最为常见,而且与人类关系密切,具有重要的公共卫生学意义。本文从宠物鸟在疫病流行传播中的意义、疫病的宿主感染谱、疫病的流行特征以及疫病的公共卫生学意义对新城疫、禽流感、鹦鹉热三种疫病进行了综述。表明宠物鸟疫病的感染率比较高,且严重危害人类健康。加强对宠物鸟疫病的检验检疫及预防,很好的防控宠物鸟类疫病具有非常重要的意义。 相似文献
994.
JUAN ANTONIO DÍAZ‐PENDÓN M. CARMEN CAÑIZARES ENRIQUE MORIONES EDUARDO R. BEJARANO HENRYK CZOSNEK JESÚS NAVAS‐CASTILLO 《Molecular Plant Pathology》2010,11(4):441-450
Tomato yellow leaf curl disease (TYLCD) is one of the most devastating viral diseases affecting tomato crops in tropical, subtropical and temperate regions of the world. Here, we focus on the interactions through recombination between the different begomovirus species causing TYLCD, provide an overview of the interactions with the cellular genes involved in viral replication, and highlight recent progress on the relationships between these viruses and their vector, the whitefly Bemisia tabaci. Taxonomy: The tomato yellow leaf curl virus‐like viruses (TYLCVs) are a complex of begomoviruses (family Geminiviridae, genus Begomovirus) including 10 accepted species: Tomato yellow leaf curl Axarquia virus (TYLCAxV), Tomato yellow leaf curl China virus (TYLCCNV), Tomato yellow leaf curl Guangdong virus (TYLCGuV), Tomato yellow leaf curl Indonesia virus (TYLCIDV), Tomato yellow leaf curl Kanchanaburi virus (TYLVKaV), Tomato yellow leaf curl Malaga virus (TYLCMalV), Tomato yellow leaf curl Mali virus (TYLCMLV), Tomato yellow leaf curl Sardinia virus (TYLCSV), Tomato yellow leaf curl Thailand virus (TYLCTHV), Tomato yellow leaf curl Vietnam virus (TYLCVNV) and Tomato yellow leaf curl virus(TYLCV). We follow the species demarcation criteria of the International Committee on Taxonomy of Viruses (ICTV), the most important of which is an 89% nucleotide identity threshold between full‐length DNA‐A component nucleotide sequences for begomovirus species. Strains of a species are defined by a 93% nucleotide identity threshold. Host range: The primary host of TYLCVs is tomato (Solanum lycopersicum), but they can also naturally infect other crops [common bean (Phaseolus vulgaris), sweet pepper (Capsicum annuum), chilli pepper (C. chinense) and tobacco (Nicotiana tabacum)], a number of ornamentals [petunia (Petunia×hybrida) and lisianthus (Eustoma grandiflora)], as well as common weeds (Solanum nigrum and Datura stramonium). TYLCVs also infect the experimental host Nicotiana benthamiana. Disease symptoms: Infected tomato plants are stunted or dwarfed, with leaflets rolled upwards and inwards; young leaves are slightly chlorotic; in recently infected plants, fruits might not be produced or, if produced, are small and unmarketable. In common bean, some TYLCVs produce the bean leaf crumple disease, with thickening, epinasty, crumpling, blade reduction and upward curling of leaves, as well as abnormal shoot proliferation and internode reduction; the very small leaves result in a bushy appearance. 相似文献
995.
996.
Arsenic release and attenuation in low organic carbon aquifer sediments from West Bengal 总被引:1,自引:0,他引:1
M. HÉRY B. E. VAN DONGEN F. GILL D. MONDAL D. J. VAUGHAN R. D. PANCOST D. A. POLYA J. R. LLOYD 《Geobiology》2010,8(2):155-168
High arsenic concentrations in groundwater are causing a humanitarian disaster in Southeast Asia. It is generally accepted that microbial activities play a critical role in the mobilization of arsenic from the sediments, with metal‐reducing bacteria stimulated by organic carbon implicated. However, the detailed mechanisms underpinning these processes remain poorly understood. Of particular importance is the nature of the organic carbon driving the reduction of sorbed As(V) to the more mobile As(III), and the interplay between iron and sulphide minerals that can potentially immobilize both oxidation states of arsenic. Using a multidisciplinary approach, we identified the critical factors leading to arsenic release from West Bengal sediments. The results show that a cascade of redox processes was supported in the absence of high loadings of labile organic matter. Arsenic release was associated with As(V) and Fe(III) reduction, while the removal of arsenic was concomitant with sulphate reduction. The microbial populations potentially catalysing arsenic and sulphate reduction were identified by targeting the genes arrA and dsrB, and the total bacterial and archaeal communities by 16S rRNA gene analysis. Results suggest that very low concentrations of organic matter are able to support microbial arsenic mobilization via metal reduction, and subsequent arsenic mitigation through sulphate reduction. It may therefore be possible to enhance sulphate reduction through subtle manipulations to the carbon loading in such aquifers, to minimize the concentrations of arsenic in groundwaters. 相似文献
997.
LÚCIA J. ROSADA CLAUDINÉIA C. S. FRANCO JULIANE R. SANT'ANNA EDILSON N. KANESHIMA MARIA CELESTE GONÇALVES‐VIDIGAL MARIALBA A. A. CASTRO‐PRADO 《The Journal of eukaryotic microbiology》2010,57(4):383-384
ABSTRACT. Heterokaryosis is the initial step of the parasexual cycle, a process that provides genetic variability in filamentous fungi through the production of heterozygous diploid nuclei. To characterize the parasexual cycle in Colletotrichum lindemuthianum, we evaluated the presence of heterokaryosis, vegetative compatibility reactions, and diploid formation among isolates of Race 65 collected from different Brazilian states. Vegetative compatibility groups were identified among the isolates according to their ability to form heterokaryons. Two heterozygous diploids were selected from compatible heterokaryons, which were characterized by the segregation of the parental auxotrophic markers and by RAPD profiles. 相似文献
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