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Summary Hypoxylon stygium (Lév)Sacc.,H. archeri Berk.,H. bovei Speg. var.microspora Miller,H. truncatum (Schw.ex Fr.)Miller,H. nummularium Bull. ex Fr. var.merillii Miller (=Hypoxylon asarcodes (Theissen)Miller?) andH. deustum (Hoff. ex Fr.)Grev. (=Ustulina zonata (Lév.)Sacc.), occurring in the tea gardens of Assam are illustrated and described. In addition, the following species ofHypoxylon hitherto reported from this country are enlisted:H. multiforme Fr. (=H. atropurpureum Fr., =H. hookeri Berk.)H. fragiforme (Pers. ex Fr.)Kickx. (=H. coccineum Bull.),H. rubiginosum Pers. ex Fr. (=H. fusco-purpureum (Schw.)Berk. et Curt., =H. nectrioides Speg., =H. perforatum Schw. ex Fr.),H. hypomiltum Mont.,H. indicum (=H. haematostroma Mont.? =H. distillatum Berk. et Fr.),H. investiens (Schw.)Curt.,H. crocopeplum Berk. et Curt. (=H. ochraceo-flavum Berk. et Cooke),H. pistillare Pers. ex Fr.,H. haematostroma Mont. (=H. vividum Berk. et Br.).H. jecorium Berk. et Rav. (=Nummularia cinnabarina P. Henn.),H. suborbiculare (=Nummularia suborbicularis (Welw. et Currey() =H. sclerophaeum Berk. et Curt? Sacc.),H. truncatum (Schw. ex Fr.)Miller (=H. annulatum (Schw.)Mont.) andH. stygium (Lév.)Sacc.  相似文献   

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From culture broth of Microsporum audouini, 5′-adenylic acid-deaminating enzyme has been purified to about 600-fold. The pH optimum was found to be 5.0 in acetate, 5.5 in succinate, 5.7 in citrate buffer. Velocity constant was 1.83×10?1 per minute. The optimal temperature was 40°C and activation energy was 15,000 calories. Michaelis-Menten constant was 6×10?4 m. This enzyme preparation removes amino groups of 5′- AMP, ADP and ATP quickly, of adenosine, 3′-AMP, 5′-deoxyAMP and NAD slowly, but adenine, 2,6-diaminopurine, 2′-AMP and NADP were not deaminated. The enzyme activity was inhibited with F?, pCMB, Fe+ + +, Cu+ + and Zn+ +  相似文献   

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The respiratory chain of Escherichia?coli contains three quinones. Menaquinone and demethylmenaquinone have low midpoint potentials and are involved in anaerobic respiration, while ubiquinone, which has a high midpoint potential, is involved in aerobic and nitrate respiration. Here, we report that demethylmenaquinone plays a role not only in trimethylaminooxide-, dimethylsulfoxide- and fumarate-dependent respiration, but also in aerobic respiration. Furthermore, we demonstrate that demethylmenaquinone serves as an electron acceptor for oxidation of succinate to fumarate, and that all three quinol oxidases of E.?coli accept electrons from this naphtoquinone derivative.  相似文献   

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Southern Elephant Seals are upper marine predators of the Southern Ocean. As such, their population dynamics and fluctuations reflect environment conditions. Their worldwide populations crashed during the second half of the twentieth century for reasons not yet completely elucidated. Here, we studied the largest population of Southern Elephant Seals within the South Indian Ocean that are breeding on ?les Kerguelen. In a previous analysis, Guinet et al. in Antarct Sci 11:193–197, 1999) suggested that the decline on ?les Kerguelen might be over, as observed elsewhere. Using 10 years of additional data, we updated this analysis using state-of-the-art statistical methods to account for most uncertainties associated with count data. We showed that the population of female Southern Elephant Seals breeding on ?les Kerguelen has been stable over the past 20 years. Despite concomitant global changes within the Southern Ocean, we did not find any evidence of a phenological shift in peak haul-out date of breeding females between the 1970s and the 2000s.  相似文献   

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Jacobs DS  Barclay RM  Walker MH 《Oecologia》2007,152(3):583-594
The peak echolocation frequency of insectivorous bats generally declines as body size increases. However, there are notable exceptions to this rule, with some species, such as Rhinolophus clivosus, having a higher than expected peak frequency for their body size. Such deviations from allometry may be associated with partitioning of foraging habitat (the foraging habitat hypothesis) or insect prey (the prey detection hypothesis). Alternatively, the deviations may be associated with the partitioning of sonar frequency bands to allow effective communication in a social context (the acoustic communication hypothesis). We tested the predictions of these hypotheses through comparisons at the family, clade and species level, using species of rhinolophids in general and R. clivosus, a species with a wide distribution, as a specific test case. We compared the wing parameters, echolocation frequency and ecology of R. clivosus to those of the sympatric R. capensis. Rhinolophus clivosus has a much higher echolocation frequency than predicted from its wing loading or body mass. Furthermore, contrary to the predictions of the foraging habitat hypothesis, we found no difference in foraging habitat between R. clivosus and R. capensis. The size range of insect prey taken by the two species also overlapped almost completely, contrary to the prey detection hypothesis. On the other hand, the variation of echolocation frequencies around the allometric relationship for rhinolophids was smaller than that for Myotis spp., supporting the prediction of the acoustic communication hypothesis. We thus propose that the relatively high peak frequency of R. clivosus is the result of partitioning of sonar frequency bands to minimize the ambiguity of echolocation calls during social interactions.  相似文献   

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γ-Type small, acid-soluble spore proteins (SASP) are the most abundant proteins in spores of at least some members of the bacterial order Bacillales, yet they remain an enigma from both functional and phylogenetic perspectives. Current work has shown that the γ-type SASP or their coding genes (sspE genes) are present in most spore-forming members of Bacillales, including at least some members of the Paenibacillus genus, although they are apparently absent from Clostridiales species. We have applied a new method of searching for sspE genes, which now appear to also be absent from a clade of Bacillales species that includes Alicyclobacillus acidocaldarius and Bacillus tusciae. In addition, no γ-type SASP were found in A. acidocaldarius spores, although several of the DNA-binding α/β-type SASP were present. These findings have elucidated the phylogenetic origin of the sspE gene, and this may help in determining the precise function of γ-type SASP.  相似文献   

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A new strain of Bacillus sp. was isolated from a hot water spring in India. This strain generated a high activity of extracellular beta-galactosidase at 37 degrees C in shake flasks. The beta-galactosidase activity was found to increase continuously but the production rate was slower than with some other organisms reported in the literature. There were noteworthy differences in the time-domain profiles of bacterial concentration and beta-galactosidase activity when the starting concentration of substrate (glucose) was tripled from 10 g/L. These differences may be explained in terms of the relative rates of enzyme synthesis and its diffusion across the cell wall. The enzyme produced by this organism is more stable than other beta-galactosidases; its half-life is 408 h at 50 degrees C and 94 h at 55 degrees C, while the reported enzymes showed perceptible loss of activity within 2 h.  相似文献   

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The flora of the copper-cobalt ores of Upper Shaba, Zaïre, comprises some 220 taxa including 42 endemics. The origin of this flora is examined and an assessment has been made of its relationship with the flora of the high plateaux steppe-savannah (dilunguan flora). A first group consists of undifferentiated species limited to these two floras. A second group comprises cupriphilous taxa derived from closely-related and widely distributed species observed on the high plateaux and elsewhere. A third group consists of closely-related species or ecotypes confined to the areas. In theSilene burchelli complex (Caryophyllaceae) there is a gradual transition from the widespreadS. burchelli var.angustifolia on the high plateaux to a newly discoveredS. burchelli ecotype from a cupriferous outcrop at Luita, and toS. cobalticola from highly mineralized copper-cobalt deposits at Mindigi. This ecophyletic series provides a gradient of morphological anatomical, and physiological changes whose end members are distinct species. The subject of palaeoendemism and neoendemism in relation to metallophytes of Upper Shaba is also discussed. Colonisation of metalliferous soils by elements of the non-mineralised high plateau is believed to be a neoendemic process.  相似文献   

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Marshall (1916) referred 26 species to genus Leptomias Fst.and .put generic names Heteromias Fst., Parisomias Fst. and Piazomias Lacd. (part) as its synonyms. Gunther and Zumpt (1933) added Cneorrhinus Redtenb.also in the list of synonyms of Leptomias st.Later on, Aslam (1961) revalidated Parisomias Fst.reshuffled the position of a few species and described a number of new species under the restricted Leptomias Fst.Accordingiy, as many as 32 species were referred to the genus Leptomias Fst.  相似文献   

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Pagria pseudograta sp. n. from Sri Lanka is described. Pagria flavopustulata and all its synonyms (Nodostoma kanaraense Jac., P. flavopustulata ab. bicolor Wse., P. signata grandis Chûjô, P. signata var. innotata Pic, and P. nodieri Pic) are placed to synonyms of P. grata Baly. Also, Nodostoma fulvipes Baly with the replacement name N. xanthopus Har., P. vignaphila Bry., and P. aeneicollis Lef. are synonymized with this species. Pagria bipunctata Lef. is placed to synonymy with P. signata (Motsch.). Nodostoma concolor Motsch. is transferred to the genus Pagria. Pagria laevifrons Jac., P. aenescens Jac. and P. recticollis Pic are transferred to the genus Cleoporus Lef. Pagria pallidicolor Pic is transferred to the genus Basilepta Baly. The drawings of the aedeagi of P. pseudograta sp. n. and P. ceylonica Pic are given. The distribution of a number of species is clarified.  相似文献   

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Spatial heterogeneity is a significant aspect of ecosystem structure andfunction. Because ecological variables often are spatially autocorrelated,standard statistics frequently are not appropriate to analyze ecological data.In this paper, we use Mantel and partial Mantel tests to explore the spatialstructure of and relationships between several variables –micro-topography, substrate salinity, wrack cover and the density ofAster laurentianus – at two sites at the peripheryofa shallow lagoon at Îles de la Madeleine, Québec.A. laurentianus is an annual halophyte endemic tothe Gulf of St. Lawrence. It typically occurs in a narrow band (from ca. 50 to200 cm wide) at the periphery of shallow lagoons. In this habitat,plants are exposed to frequent deposition of plant debris (wrack) and to thelimiting effects of substrate salinity.Our analyses show that substrate salinity, wrack cover and density ofA. laurentianus are significantly correlated withtopography, and that wrack cover affects substrate salinity at both sites. Atthe first site, the abundance of A. laurentianus increasesprogressively with distance from the waterline, while at the second site,density increases initially, but then diminishes with distance from thewaterline. At the first site, the most important structuring variable is wrackdeposition, the effect of salinity on plant density being indirect. At thesecond site, which is somewhat sheltered, wrack deposition is far lessimportantand substrate salinity predominates over wrack deposition as structuringvariable. We suggest that A. laurentianus distributionalong the shores of shallow lagoons is limited both by substrate salinity andwrack deposition, but that the relative importance of these structuringvariables changes with the physical characteristics of the site.  相似文献   

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Can the cause of aggregation be inferred from species distributions?   总被引:2,自引:0,他引:2  
Species distributions often show an aggregated pattern, which can be due to a number of endo- and exogenous factors. While autologistic models have been used for modelling such data with statistical rigour, little emphasis has been put on disentangling potential causes of aggregation. In this paper we ask whether it is possible to infer sources of aggregation in species distributions from a single set of occurrence data by comparing the performance of various autologistic models. We create simulated data sets, which show similar occupancy patterns, but differ in the process that causes the aggregation. We model the distribution of these data with various autologistic models, and show how the relative performance of the models is sensitive to the factor causing aggregation in the data. This information can be used when modelling real species data, where causes of aggregation are typically unknown. To illustrate, we use our approach to assess the potential causes of aggregation in data of seven bird species with contrasting statistical patterns. Our findings have important implications for conservation, as understanding the mechanisms that drive population fluctuations in space and time is critical for the development of effective management actions for long-term conservation.  相似文献   

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The V max of an extracellular, thermostable -amylase from Bacillus licheniformis 44MB82 were 5.70×10-3 and 9.70×10-3 mM s-1 at 30 and 90°C, respectively, whereas the K m values were similar (0.9 mg ml-1) at both temperatures. Excluding dextrins, the dominant products from soluble starch and amylopectin hydrolysis contained less than six glucose residues. The enzyme hydrolysed amylopectin better than soluble starch. Increasing the temperature from 30 to 90°C was accompanied by an increase in the production of malto-oligosaccharides, especially maltotetrose, and this was related to the secondary hydrolysis of maltopentose and maltohexose.The authors are with the Institute of Microbiology, Bulgarian Academy of Sciences, Sofia 1113. 26 Academician G. Bonchev, Bulgaria  相似文献   

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Two new species of the genus Eumyllocerus Sharp, 1896, of the subfamily Entiminae Schoenherr, 1823, are described from China. Eumyllocerus longisetus sp. n. may be distinguished from other species of the genus by its long bristle-like, erect setae on the intervals, each of which is longer than the width of the second interval, the setae arrangedin double rows, and its shell-like, shiny, dense, metallic green scales. Eumyllocerus rotundicorpus sp. n. may be distinguished from any other Eumyllocerus species by its oval and inflated elytral shape, short stout metepisternum, small humeri, elytral setae shorter than 0.5 times the width of the second interval, the setae arranged in double rows, and its golden copper and pearl gray scales. The taxonomy of the genus is discussed. The two new species are described and habitus photographs and figures of diagnostic characters are provided. The type specimens of the new species are deposited in the Institute of Zoology, Chinese Academy of Sciences, Beijing, China (holotype and paratypes) and the Korean Entomological Institute, Korea University, Seoul, Korea (paratypes).  相似文献   

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We review our recent work in the field of molecule-based magnets showing the structural and magnetic properties of a special class of hybrid organic–inorganic compounds, i.e. metal(II) organophosphonates. The synthesis, the crystal structures and, in particular, the magnetic studies of selected examples of compounds of formulas M(II)[(R–PO3)(H2O)], and M2[(O3P–R′–PO3)(2H2O)] M = Cr, Fe, Co; R = CnH2n+1, n = 1, 2, 3… and C6H5, R′ = (CH2)2 prepared in our laboratory are presented and discussed. Metal alkylphosphonates, except those of Co(II), are weak ferromagnets at low temperatures. The observed magnetic ordering temperature TN varies from 4.2 to 25 K, depending on the transition metal ions and on crystal and molecular structure. Moreover, in the case of a bifunctional molecule like aminoethylphosphonic acid, NH2(CH2)2PO3H2, or the carboxyethylphosphonic acid, HO2C(CH2)2PO3H2, is used as a ligand, then a novel Cr(II) compound of formula Cr[NH3(CH2)2PO3(Cl)(H2O)] and a microporous Fe(III) salt (NH4)[Fe2(OH){O3P(CH2)2CO2}2] are isolated. The latter are both polar and, more interesting, Cr(II) ammoniumethylphosphonate chloride results to be a weak ferromagnet below TN = 5.0 K.  相似文献   

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