首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
2.
A new species of Ulocladium was discovered from diseased leaves of Lycopersicon esculentum and Duchesnea indica from Hunan Province of China. Morphologically, this species is very close to U. consortiale, U. cucurbitae, and U. subcucurbitae in producing narrow ellipsoid conidia at 13 days, but the conidial size range of this species at this stage could distinguish it from three well-known species. It also exhibits the multiplex conidium morphology at the different growth-stages (1–3 days and 4–7 days). The results of maximum parsimony (MP) and neighbor-joining (NJ) phylogenetic analyses of combined glyceraldehyde-3-phosphate dehydrogenase (gpd) gene and Alternaria alternata major allergen (Alt a 1) genes show that U. solani and U. subcucurbitae cluster in a unique and separate subclade with no clear affinities to a specific sistergroup, and demonstrate that the Ulocladium species group is monphyletic, but two clades of this section are recognized. Morphological features of this new species, the sequences of the Alt a 1 and gpd gene regions, and its comparison with related species in this genus are discussed.  相似文献   

3.
2021年8月,在安徽省合肥市庐江县牛王寨采集到东亚腹链蛇属(Hebius)蛇类标本1号。经形态比较发现,该蛇明显不同于大别山地区已有的东亚腹链蛇属物种——棕黑腹链蛇(H. sauteri)和绣链腹链蛇(H. craspedogaster)。分子系统学分析显示,该标本与东亚腹链蛇(H. vibakari)遗传关系最近,且形态上符合东亚腹链蛇特征,提示该标本应为东亚腹链蛇。东亚腹链蛇是安徽省和大别山地区爬行动物分布新记录种,这也是该物种在中国东北地区之外首次被报道。该分布新记录扩大了对东亚腹链蛇的分布范围的认知,对东亚腹链蛇的种群分化和生物地理学研究具有重要意义。  相似文献   

4.
Genome sequence analysis of Xanthomonas oryzae pv. oryzae has revealed a cluster of 12 ORFs that are closely related to the gum gene cluster of Xanthomonas campestris pv. campestris. The gum gene cluster of X. oryzae encodes proteins involved in xanthan production; however, there is little experimental evidence supporting this. In this study, biochemical analyses of xanthan produced by a defined set of X. oryzae gum mutant strains allowed us to preliminarily assign functions to most of the gum gene products: biosynthesis of the pentasaccharide repeating unit for GumD, GumM, GumH, GumK, and GumI, xanthan polymerization and transport for GumB, GumC, GumE, and GumJ, and modification of the pentasaccharide repeating unit for GumF, GumG, and GumL. In addition, we found that the exopolysaccharides are essential but not specific for the virulence of X. oryzae. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Sang-Yoon Kim and Jeong-Gu Kim contributed equally to this work.  相似文献   

5.
Gall‐forming insects are commonly highly host‐specific, and galling species once thought to be oligo‐ or polyphagous are often found to represent a complex of host‐specific races or cryptic species. A recent DNA barcoding study documented that an unidentified species of the genus Adelges is a gall‐former associated with four spruce species (Picea bicolor, P. koyamai, P. maximowiczii, P. polita) as the primary hosts, with little genetic differentiation among insects on different host species. In this study, we investigated the morphology of this galling adelgid to determine its taxonomic identity. Morphological inspection of insects collected from three of the spruce species confirmed that this adelgid is a single galling species, and is identified as Adelges (Sacchiphantes) kitamiensis, which was previously known only from the secondary host. We described the gallicola adults of this species, as well as the first‐instar exules which are the offspring of gallicolae. Finally, we verified the taxonomic identity of this species and discuss its life cycle and host distribution.  相似文献   

6.
7.
2021年8月,在安徽省合肥市庐江县牛王寨采集到东亚腹链蛇属(Hebius)蛇类标本1号。经形态比较发现,该蛇明显不同于大别山地区已有的东亚腹链蛇属物种——棕黑腹链蛇(H. sauteri)和绣链腹链蛇(H. craspedogaster)。分子系统学分析显示,该标本与东亚腹链蛇(H. vibakari)遗传关系最近,且形态上符合东亚腹链蛇特征,提示该标本应为东亚腹链蛇。东亚腹链蛇是安徽省和大别山地区爬行动物分布新记录种,这也是该物种在中国东北地区之外首次被报道。该分布新记录扩大了对东亚腹链蛇的分布范围的认知,对东亚腹链蛇的种群分化和生物地理学研究具有重要意义。  相似文献   

8.
Five genes for tryptophan biosynthesis, trpE, trpD, trpC, trpB, and trpA of Brevibacterium lactofermentum, a coryne form glutamic acid-producing bacterium, were cloned as a 9.6 kb BamHl DNA fragment by colony hybridization. A previously cloned 1.2 kb Pst I DNA fragment containing a major part of the trpE gene was used as a probe. By complementation tests using the subclones of this 9.6 kb BamHl fragment and various tryptophan auxotrophs of B. lactofermentum and Escherichia coli, this fragment was found to contain a gene cluster composed of trpE, trpD, trpC, trpB, and trpA in this order. It suggests that genes for tryptophan biosynthesis in B. lactofermentum may be an operon.  相似文献   

9.
In Japan, a Mycobacterium marinum‐like mycobacterium was isolated from the yellowtail, Seriola quinqueradiata. The species was identified as M. marinum by a commercial mycobacterial DNA‐DNA hybridization kit. Nevertheless, PCR restriction analysis of the DNA of its RNA polymerase β‐subunit gene definitively showed that this Mycobacterium sp. was M. ulcerans. PCR analysis revealed the genotypic characteristics of M. ulcerans in the Mycobacterium sp., only the mup053 gene sequence being absent, as has been found previously in other piscine mycobacteria such as M. marinum strains DL240490 and DL045 and M. pseudoshottsii. With one exception, this Mycobacterium sp. and M. pseudoshottsii had identical 16S rRNA gene sequences, which is also probably true of M. marinum strains DL240490 and DL045. Similarly, according to comparisons of the 16S rRNA gene, ITS region, and hsp65 gene sequences, this Mycobacterium sp. is more closely related to M. pseudoshottsii than to M. ulcerans or M. marinum. A PCR product of approximately 2000 bp was amplified from region of difference 9 in the Mycobacterium sp. The nucleotide sequence revealed insertion of IS2404, the sequence of which is 1366 bp long. The novel single nucleotide polymorphisms identified in this region distinguished this Mycobacterium sp. from M. marinum strain DL240490 and M. pseudoshottsii. The present findings raise the possibility that these species have a common ancestor. Further studies are required to improve our understanding of the relationship between their geographical origin and genetic diversity.  相似文献   

10.
Thus far an individual height growth curve hij(t) of the i-th person in the j-th period, t being his (or her) age, has been studied as a function of t associated with its velocity curve. In this note we introduce a natural scale X(t) in place of t, which linearizes this personal curve and facilitates its analysis, in the sense that this equation of growth contains apparently two personal parameters for one period but one of them plays an essential role. The effectiveness of this approach will be seen in four figures.  相似文献   

11.
Recently, we identified and characterized the genes encoding several distinct members of the histidine-acid phosphatase enzyme family from Leishmania donovani, a primitive protozoan pathogen of humans. These included genes encoding the heavily phosphorylated/glycosylated, tartrate-sensitive, secretory acid phosphatases (Ld SAcP-1 and Ld SAcP-2) and the unique, tartrate-resistant, externally-oriented, surface membrane-bound acid phosphatase (Ld MAcP) of this parasite. It had been previously suggested that these enzymes may play essential roles in the growth, development and survival of this organism. In this report, to further examine this hypothesis, we assessed whether members of the L. donovani histidine-acid phosphatase enzyme family were conserved amongst other pathogenic Leishmania and related trypanosomatid parasites. Such phylogenetic conservation would clearly indicate an evolutionary selection for this family of enzymes and strongly suggest and support an important functional role for acid phosphatases to the survival of these parasites. Results of pulsed field gel electrophoresis and Southern blotting showed that homologs of both the Ld SAcPs and Ld MAcP were present in each of the visceral and cutaneous Leishmania species examined (i.e. isolates of L. donovani, L. infantum,L. tropica, L. major and L. mexicana, respectively). Further, results of enzyme assays showed that all of these organisms expressed both tartrate-sensitive and tartrate-resistant acid phosphatase activities. In addition, homologs of both the Ld SAcPs and Ld MAcP genes and their corresponding enzyme activities were also identified in two Crithidia species (C. fasciculata and C. luciliae) and in Leptomonas seymouri. In contrast, Trypanosoma brucei, Trypanosoma cruzi and Phytomonas serpens had only very low levels of such enzyme activities. Cumulatively, results of this study showed that homologs of the Ld SAcPs and Ld MAcP are conserved amongst all pathogenic Leishmania sps. suggesting that they may play significant functional roles in the growth, development and survival of all members of this important group of human pathogens.  相似文献   

12.
The genus Filipendula Mill. is generally separated from Spiraea L. in systematic keys on the basis of a single fruit character. In some taxonomic treatments of the Rosaceae, where subfamilies are used, this places the genera in separate subfamilies. Karyological studies can be useful in assaying the justifiability of such treatment and are needed because of serious discrepancies between previous reports of chromosome numbers and the recent textbook designation, on dubious grounds, of F. vulgaris as an example of a “permanent chromosome hybrid.” The results given in this paper show that x = 7 in this genus (compared with x = 9 in Spiraea) and the reasons for rejecting previous counts of 2n = 15 for F. vulgaris are presented. “Permanent chromosome hybridity” for this species is also rejected. The possibility that a cytotype with 2n = 16 may exist in the northern part of the range of F. ulmaria cannot be completely discounted, but positive evidence is presented for 2n = 14 in this species (even though 2n = 16 has been reported most frequently recently). The basic number 7 for Filipendula is in agreement with the placing of this genus in the subfamily Rosoideae even though the hereditary peculiarities (apomixis and permanent chromosome hybridity) shown by some other members of this subfamily are apparently not now needed to explain the cytological situation in Filipendula.  相似文献   

13.
Abstract Harmonia axyridis Pallas (Coleoptera: Coccinellidae) is an invasive specie affecting the dynamics and composition of several guilds. Nowadays, no biological control method is available to reduce the populations of this harmful coccinellid. Attractants and semiochemicals seem to be the best alternative but only few studies have tested the impact of semiochemicals on this Asian lady beetle. In this work, through wind‐tunnel experiments, semiochemicals from aphids (Z,E‐nepetalactone, [E]‐β‐farnesene, α‐pinene and β‐pinene), from coccinellids ([‐]‐β‐caryophyllene) and from the nettle Urtica dioica L. were evaluated as potential attractants. The nettle volatile compounds ([Z]‐3‐hexenol and [E]‐2‐hexenal) were extracted using a Clevenger Apparatus® and identified by headspace gas chromatography–mass spectroscopy. In the wind‐tunnel experiments, the main components of the aphid alarm pheromone as well as a component of the aphid sexual pheromone strongly attracted both sexes of the Asian lady beetle while (‐)‐β‐caryophyllene only attracted few individuals and had no impact on the males. The nettle extract as well as the (Z)‐3‐hexenol oriented both males and females to the odor source. The (E)‐2‐hexenal was shown to have no effect on females even if this green leaf volatile attracted males. Because Z,E‐nepetalactone was identified as the most efficient attractant in the wind‐tunnel experiments, this volatile was also tested in a potato field where H. axyridis has been showed to respond to this semiochemical. This study highlighted that Z,E‐nepetalactone orientated the Asian lady beetle H. axyridis under natural conditions, indicating that this volatile compound could certainly help for an efficient biological control approach against this invasive specie.  相似文献   

14.
Abstract

The European heathers Erica manipuliflora, Erica multiflora and Erica vagans (sect. Gypsocallis) are related species characterized by a glabrous ovary, exerted, muticous anthers and a pale pink, urceolate corolla. The existence of three species is the most accepted treatment for this group, but there are uncertainties about this taxonomic interpretation. In this article, we used seed morphological characters to assess the systematics of the group. Seeds were studied by means of scanning electron microscopy techniques. E. multiflora has a distinct seed type, 1–1.5 mm long, flattened, yellowish with a striate-reticulate primary sculpture. E. vagans and E. manipuliflora have smaller seeds, brown with a reticulate pattern. Seeds of E. vagans are globose, 0.5 mm wide, while E. manipuliflora has mostly ellipsoid seeds 0.7 mm long. However, seeds of E. manipuliflora from the Adriatic coasts are closer to those of E. vagans, and this may support the existence of E. manipuliflora subsp. anthura.  相似文献   

15.
In order to make the tomato genome more accessible for molecular analysis and gene cloning, we have produced 405 individual tomato (Lycopersicon esculentum) lines containing a characterized copy of pJasm13, a multifunctional T-DNA/modifiedDs transposon element construct. Both the T-DNA and the Ds element in pJasm13 harbor a set of selectable marker genes to monitor excision and reintegration of Ds and additionally, target sequences for rare cutting restriction enzymes (I-PpoI, SfiI, NotI) and for site-specific recombinases (Cre, FLP, R). Blast analysis of flanking genomic sequences of 174 T-DNA inserts revealed homology to transcribed genes in 69 (40%), of which about half are known or putatively identified as genes and ESTs. The map position of 140 individual inserts was determined on the molecular genetic map of tomato. These inserts are distributed over the 12 chromosomes of tomato, allowing targeted and non-targeted transposon tagging, marking of closely linked genes of interest and induction of chromosomal rearrangements including translocations or creation of saturation-deletions or inversions within defined regions linked to the T-DNA insertion site. The different features of pJasm13 were successfully tested in tomato and Arabidopsis thaliana, thus providing a new tool for molecular/genetic dissection studies, including molecular and physical mapping, mutation analysis and cloning strategies in tomato and potentially, in other plants as well.Equal contributors to this workEqual contributors to this workEqual contributors to this workEqual contributors to this workEqual contributors to this workEqual contributors to this workEqual contributors to this workEqual contributors to this workEqual contributors to this workEqual contributors to this workEqual contributors to this workEqual contributors to this work  相似文献   

16.
Summary A 1.9 kb clone of the T-DNA region of the Agrobacterium tumefaciens Ti plasmid Bo542 which exhibited homology to the isopentenyl transferase (ipt) locus of pTiA6 was identified by low stringency DNA hybridization. Introduction of this segment of pTiBo542 DNA into cells of Nicotiana tabacum or N. glauca caused tumor formation in vivo, and allowed hormone independent growth in vitro. Furthermore, this DNA segment complemented ipt mutant strains of A. tumefaciens, restoring their ability to cause tumors on Kalanchöe leaves and tomato stems. The complete DNA sequence of this segment has been determined, revealing an open reading frame homologous to other known Agrobacterium ipt genes.  相似文献   

17.
Li B  Mao D  Liu Y  Li L  Kuang T 《Photosynthesis research》2005,83(3):297-305
A pure, active cytochrome b 6 f was isolated from the chloroplasts of the marine green alga, Bryopsis corticulans. To investigate and characterize this cytochrome b 6 f complex, sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS–PAGE), absorption spectra measurement and HPLC were employed. It was shown that this purified complex contained four large subunits with apparent molecular masses of 34.8, 24, 18.7 and 16.7 kD. The ratio of Cyt b 6 to Cytf was 2.01 : 1. The cytochromeb 6 f was shown to catalyze the transfer of 73 electrons from decylplastoquinol to plastocyanin–ferricyanide per Cyt f per second. α-Carotene, one kind of carotenoid that has not been found to present in cytochrome b 6 f complex, was discovered in this preparation by reversed phase HPLC. It was different from β-carotene usually found in cytochrome b 6 f complex. The configuration of the major α-carotene component was assigned to be 9-cis by resonance Raman spectroscopy. Different from the previous reports, the configuration of this α-carotene in dissociated state was determined to be all-trans. Besides this carotene, chlorophyll a was also found in this complex. It was shown that the molecular ratios of chlorophylla, cis and all-trans-α-carotene to Cyt f in this complex were 1.2, 0.7 and 0.2, respectively.  相似文献   

18.
The main objectives of this study were (1) to describe the diversity of mycorrhizal fungal communities associated with Uapaca bojeri, an endemic Euphorbiaceae of Madagascar, and (2) to determine the potential benefits of inoculation with mycorrhizal fungi [ectomycorrhizal and/or arbuscular mycorrhizal (AM) fungi] on the growth of this tree species and on the functional diversity of soil microflora. Ninety-four sporophores were collected from three survey sites. They were identified as belonging to the ectomycorrhizal genera Afroboletus, Amanita, Boletus, Cantharellus, Lactarius, Leccinum, Rubinoboletus, Scleroderma, Tricholoma, and Xerocomus. Russula was the most frequent ectomycorrhizal genus recorded under U. bojeri. AM structures (vesicles and hyphae) were detected from the roots in all surveyed sites. In addition, this study showed that this tree species is highly dependent on both types of mycorrhiza, and controlled ectomycorrhization of this Uapaca species strongly influences soil microbial catabolic diversity. These results showed that the complex symbiotic status of U. bojeri could be managed to optimize its development in degraded areas. The use of selected mycorrhizal fungi such the Scleroderma Sc1 isolate in nursery conditions could be of great interest as (1) this fungal strain is very competitive against native symbiotic microflora, and (2) the fungal inoculation improves the catabolic potentialities of the soil microflora.  相似文献   

19.
Li X  Liu M  Goldberg JD 《Biometrics》2011,67(4):1666-1668
Summary Exact unconditional tests have been widely applied to test the difference between two probabilities for 2 × 2 matched‐pairs binary data with small sample size. In this context, Lloyd (2008, Biometrics 64 , 716–723) proposed an E + M p ‐value, that showed better performance than the existing M p ‐value and C p ‐value. However, the analytical calculation of the E + M p ‐value requires that the Barnard convexity condition be satisfied; this can be challenging to prove theoretically. In this article, by a simple reformulation, we show that a weaker condition, conditional monotonicity, is sufficient to calculate all three p ‐values (M, C , and E + M ) and their corresponding exact sizes. Moreover, this conditional monotonicity condition is applicable to noninferiority tests.  相似文献   

20.
A part of the gene encoding cbb 3-type cytochrome oxidase CcoN subunit was cloned from Azotobacter vinelandii and a mutant strain of this bacterium with disrupted ccoN gene was constructed. In contrast to the wild type strain, this one is unable to oxidize cytochromes c 4 and c 5. Thus, the A. vinelandii respiratory chain is shown to contain cbb 3-type cytochrome c oxidase. It is also shown that the activity of this enzyme is not necessary for diazotrophic growth of A. vinelandii at high oxygen concentrations.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号