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1.
Since 1997 two distinct geminivirus species, Tomato yellow leaf curl Sardinia virus (TYLCSV) and Tomato yellow leaf curl virus (TYLCV), have caused a similar yellow leaf curl disease in tomato, coexisted in the fields of southern Spain, and very frequently doubly infected single plants. Tomatoes as well as experimental test plants (e.g., Nicotiana benthamiana) showed enhanced symptoms upon mixed infections under greenhouse conditions. Viral DNA accumulated to a similar extent in singly and doubly infected plants. In situ tissue hybridization showed TYLCSV and TYLCV DNAs to be confined to the phloem in both hosts, irrespective of whether they were inoculated individually or in combination. The number of infected nuclei in singly or doubly infected plants was determined by in situ hybridization of purified nuclei. The percentage of nuclei containing viral DNA (i.e., 1.4% in tomato or 6% in N. benthamiana) was the same in plants infected with either TYLCSV, TYLCV, or both. In situ hybridization of doubly infected plants, with probes that discriminate between both DNAs, revealed that at least one-fifth of infected nuclei harbored DNAs from both virus species. Such a high number of coinfected nuclei may explain why recombination between different geminivirus DNAs occurs frequently. The impact of these findings for epidemiology and for resistance breeding concerning tomato yellow leaf curl diseases is discussed.  相似文献   

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In this paper, a newCampanula species is described from Eastern Slovakia. Its morphological, distributional and cytological relationships and ecological preferences are briefly discussed and affinity to the otherSaxicolae examined. The taxon is characterized by the following features: specific combination of constant morphological characters; diploid chromosome number (2n=34); ecological specialization to the fissures of limestone and dolomitic rocks; relict occurrence in a small, sharply limited area; very late flowering. Geographically, it appears to be the northernmost representative of theSaxicolae.  相似文献   

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Li W  Ji YL  Yu HS  Wang ZW 《Mycologia》2006,98(4):560-570
Epichlo? species are fungal symbionts (endophytes) of grasses, six European and four North American biological species in genus Epichlo? have been described in previous researches. In this study we describe a new Epichlo? species, Epichlo? yangzii Li et Wang, found in natural symbioses with Roegneria kamoji native to China. We investigated the host specificity, morphology, interfertility tests and molecular phylogenetic evidences of this new species. The results indicated that E. yangzii is host specific and seedborne. Most morphological characteristics of this new species are typical in the genus. However differences are evident in several features including size of perithecia, asci and ascospores. In mating tests E. yangzii was not interfertile with E. elymi isolates from related hosts in genera Elymus. Phylogenetic relationships based on sequences of beta-tubulin gene (tub2) introns and translation elongation factor 1-alpha gene (tef1) introns showed that members of the new species grouped into exclusive clades with high bootstrap value.  相似文献   

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Pinguicula rotundiflora (Lentibulariaceae), a new species from southern Mexico related toP. parvifolia Robinson is described and illustrated.  相似文献   

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Summary The proteolytic activity produced by a new species of Bacillus isolated in our laboratory was investigated. This enzyme was purified to homogeneity from cell-free culture liquids of B. thermoruber. The purification procedure included ion-exchange chromatography on DEAE-Sephadex A-50 and -casein agarose affinity chromatography. The protease consists of one polypeptide chain with a molecular weight of 39000±800. the isoelectric point was 5.3; the optimum pH and temperature for proteolytic activity (on casein) was found to be pH 9 and 45°C respectively. Enzyme activity was inhibited by PMSF and EDTA. The stability was considerably increased by addition of Ca2+, and the protease exhibited a relatively high thermal stability. The alkaline protease shows a preference for leucine in the carboxylic side of the peptide bond of the substrate. The K m value for benzyloxycarbonyl-Ala-Ala-Leu-p-nitroanilide was 2.5 mM.  相似文献   

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A new species of Megischus Brullé from China, Megischus aplicatussp. n.,is described and illustrated. A key to the Chinese species of Megischus is added. The holotype is deposited in the Parasitic Hymenoptera Collection of Zhejiang University, Hangzhou.  相似文献   

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Abstract

The discover and morphological characters of a Dematiaceous Hyphomycetes are described. The material, studied under a morphological point of view directly collected on the natural substratum, allows us to establish the appartenance to the genus Chaetopsina. Since this species does not appeare described till now, the Authors propose for it the nomenclature ivoriensis as a new species.  相似文献   

11.
In this paper, a newCampanula species is described from Eastern Slovakia. Its morphological, distributional and cytological relationships and ecological preferences are briefly discussed and affinity to the otherSaxicolae examined. The taxon is characterized by the following features: specific combination of constant morphological characters; diploid chromosome number (2n = 34); ecological specialization to the fissures of limestone and dolomitic rocks; relict occurrence in a small, sharply limited area; very late flowering. Geographically, it appears to be the northernmost representative of theSaxicolae.  相似文献   

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A new species Pholiota chocenensis is described based on collections from the Czech Republic and Italy. Both the macro- and micromorphology and the the ITS-LSU rDNA sequences showed that P. chocenensis differs from all European species of Pholiota sect. Spumosae. Its key diagnostic characters are: medium-sized fruitbodies, pileus strongly glutinous, yellow-brown to orange with a rusty-brown tinge, with paler margin covered by whitish fibrillose-flocculose veil remnants, stipe covered with distinct, dense, fibrillose-floccose to floccose-scaly veil remnants of yellow-rusty to rusty-orange colour, spores ovoid, 6.4–8?×?4.4–4.8 μm, abundant cheilo- and pleurocystidia of utriform to fusiform-lageniform shape, growth on soil. Molecularly, it is unique by a 68-bp-long insert in the ITS-LSU rDNA gene which is absent in other Pholiota species. Similar European and North American taxa are compared. A possible synonymy of P. brunnescens with P. highlandensis is discussed.  相似文献   

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Summary A method is described for large scale routine phenotyping of haptoglobin (Hp) which allows complete subtyping without prior purification of the Hp molecule. The procedure includes polyacrylamide gel isoelectric focusing of reduced, neuraminidase treated serum or plasma samples, and nitrocellulose blots developed with the immunoperoxidase technique. Different variables including sample treatment, electrofocusing, blotting procedures, and immunoperoxidase visualization are discussed.Characteristic -chain patterns allow identification of the common allotypes 2FS, 2SS, 2FF, IS, IF, and Johnson. Isoelectric variations in the -chain may also be recognized. For comparison, two-dimensional Hp-patterns are presented. The results from concurrent typing of 600 samples by ordinary starch gel electrophoresis and by the described isofocusing technique, are evaluated.  相似文献   

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Pennilabium yunnanense S. C. Chen&Y. B. Luo,a new species of Orchidaceae,is described and illustra ted. It is subsimilar to P. acuminatum(Ridley)Holttum,from which it dif-fers by having smaller flowers ca. 3cm across,white petals spotted with dark purple adaxially and fimbriate-tipped side-lobes of the lip.  相似文献   

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A new species of camaenid land snail, Satsuma jinlunensis n. sp., from southeastern Taiwan is established. This species inhabits the lowland forests with a narrow geographical distribution insofar as we know. The species is characterised by having a sinistral shell, a rounded periphery, an oblique columellar lip joining the basal lip smoothly, an open umbilicus, a coiled flagellum, an absent or weakly developed penial caecum, a hemispherical verge internally, and a pedunculus of the bursa copulatrix expanded medially. The new species is distinguishable from congeners by a combination of its sinistral and conical shell, and coiling of the flagellum and part of the epiphallus. The characteristics of male genitalia and species biodiversity of terrestrial snails in southern Taiwan are discussed.

http://zoobank.org/urn:lsid:zoobank.org:pub:96F3118C-09B9-4ED4-AAB7-2DBEE978459F  相似文献   


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Two cladid crinoid species, ?Ulocrinus indicus Wanner, 1924, and ?Ulocrinus conoideus Wanner, 1937, are reinterpreted as cladid crinoids that do not belong to the cromyocrinids. This justifies Wanner's questioning of the generic assignment. ?Ulocrinus indicus has bifascial radial facets and is considered an advanced intermediate dendrocrinid assigned to the incertae superfamiliae, Katerocrinidae n. fam., Katerocrinus indicus n. gen., n. comb. This extends the range of the bifascial dendrocrinids upward into the Permian. ?Ulocrinus conoideus has trifascial radial facets and is assigned to the superfamily Scytalocrinoidea, incertae familiae, Dochmocrinus conoideus n. gen., n. comb. It re-emphasizes the need for revision of the family Scytalocrinidae. An unnamed, poorly preserved cup is described and considered to be a pelecocrinid crinoid, thus adding to the diversity of the West Timor Permian crinoids.  相似文献   

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Carex subcapitata X.F.Jin,C.Z.Zheng&B.Y.Ding,a new species of Cyperaceae from Zhejiang,China,is described and illustrated.It is related to C.grandiligulata K kenth.in having lateral culms,narrow leaves,spikelets androgynous,1-2arising from each node,but d  相似文献   

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