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 0 毫秒
1.
Following a re-examination of the material treated under Barleria brevispina (Fiori) Hedrén in the recent Flora of Somalia account of the Acanthaceae, it is concluded that two distinct species are involved and Barleria compacta Malombe & I. Darbysh. is described here from north-eastern Somalia. Its affinities and conservation status are discussed.  相似文献   

2.
The intron sequence of chloroplast rpS16 and the secondary structure of its pre-mRNA were characterized for the first time in 26 Allium sativum accessions of different ecologo-geographical origins and seven related Allium species. The boundaries and main stem-loop consensus sequences were identified for all six domains of the intron. Polymorphism was estimated for the total intron and its regions. The structural regions of the rpS16 intron proved to be heterogeneous for mutation rate and spectrum. Mutations were most abundant in domains II and IV, and transition predominated in domains I, III, V, and VI. In addition to structural elements and motifs typical for group IIB introns, several Allium-specific micro- and macrostructural mutations were revealed. A 290-bp deletion involving domains III and IV and part of domain V was observed in A. altaicum, A. fistulosum, and A. schoenoprasum. Several indels and nucleotide substitutions were found to cause a deviation of the pre-mRNA secondary structure from the consensus model of group II introns.  相似文献   

3.
Boletus kermesinus, a new species of Boletus section Luridi, is fully described and illustrated based on the materials collected in subalpine coniferous forests of central Honshu, Japan. It has distinctive features of dark-red basidiomata having distinct viscidity in the pileus surface, usually unchanging flesh, discolorous red pores, and an entirely reticulate stipe becoming coarsely lacerate-rimose with age.  相似文献   

4.
In vitro regeneration of black nightshade (Solanum nigrum L.) plants was achieved through callus-mediated shoot organogenesis followed by 30 d indoor ex vitro adaptation to nutritional stress under environmental ambience and thereafter 6-d outdoor acclimatization in pots prior to field establishment. Relevant physiological parameters including pigment content, chlorophyll a fluorescence, net photosynthetic rate (P N), transpiration rate (E), and stomatal conductance (g s) of in vitro-regenerated plants were investigated during the course of ex vitro adaptation. During the first 4 d of indoor transplantation to potting substrate, there was a marginal reduction in the leaf chlorophyll and carotenoid contents but P N and E were strongly reduced. The stomatal conductance and E/P N ratio were significantly higher in plants up to 20 d of indoor adaptation than those of comparable age grown naturally from seeds. The shape of the OJIP fluorescence transient varied significantly with acclimatization, and the maximum change was observed at 2.0 ms. The 2.0 ms variable fluorescence (V j), 30 ms relative fluorescence (M 0), photon trapping probability (TR0/Abs), and photosystem II (PSII) trapping rate (TR0/RC) showed initial disturbance and subsequent stabilization during 30 d of indoor acclimatization. Energy dissipation (DI0/RC) and electron transport probability (ET0/TR0) showed an initial phase of increase during the 4 d after plants were transplanted outdoors. During the 6-d outdoor acclimatization after transfer of plants to soil, no significant change in total chlorophylls and carotenoids, E, and g s were observed, but P N improved after reduction on the first d. The OJIP-derived parameters experienced change on the first d but were stabilized quickly thereafter. There was no significant difference between outdoor acclimatized plants and those of the seed-grown plants of comparable age with respect to photosynthetic and fluorescence parameters. Direct transfer of plants without indoor acclimatization, however, showed a completely different trend with respect to P N, E, and OJIP fluorescence transients. The bearing of this study on optimizing micropropagation is discussed.  相似文献   

5.
There are three most important bacterial causative agents of serious infections that could be misused for warfare purposes: Bacillus anthracis (the causative agent of anthrax) is the most frequently mentioned one; however, Fracisella tularensis (causing tularemia) and Yersinia pestis (the causative agent of plague) are further bacterial agents enlisted by Centers for Disease Control and Prevention into the category A of potential biological weapons. This review intends to summarize basic information about these bacterial agents. Military aspects of their pathogenesis and the detection techniques suitable for field use are discussed.  相似文献   

6.
A new species of Lamiaceae from Belize: Hyptis maya is described and illustrated. It is closely related to the more widespread H. lanceolata Poir., with which it is compared.  相似文献   

7.
8.
In order to investigate chromosome elimination in symmetric somatic hybridization between Bupleurum scorzonerifolium and Arabidopsis thaliana, protoplasts were isolated from suspension cultures of both A. thaliana and B. scorzonerifolium parents. Biparental protoplasts were mixed at a rate of 1.5:1 and fused with PEG-method. After protoplast fusion, the products were cultured in the P5 liquid medium for microcallus formation. Single cell lines formed from microcalli after subculturing on the MB1 (Xia and Chen, Plant Sci 120:197–203, 1996) solid medium. The putative somatic hybrid cell lines were identified by cytological and molecular analysis. Of the 132 somatic cell lines generated, 16 were identified as somatic hybrids, with the phenotypes resembled B. scorzonerifolium parent. These hybrids showed a complete set of B. scorzonerifolium chromosome and 0–2 small chromosome(s) of A. thaliana. A few of them showed nuclear and cytoplasmic SSR fragments of A. thaliana. These hybrid cell lines could differentiate to green spots, buds/leaves through complementation of regeneration ability. The chromosomes elimination of A. thaliana was discussed. Wang Minqin and Zhao Junsheng contributed equally to the work.  相似文献   

9.
10.
In the crude ethanol extracts obtained from the rhizome and roots of Rheum palmatum L., Rheum undulatum L. and Rheum rhaponticum L. growing in Poland concentration of polyphenols ranged from 46.11 to 76.45 mg/g. Concentration of tannins ranged from 7.07% to 8.67%, while anthracene derivatives and anthraquinones varied by species - R. palmatum measured 36.3 and 34 mg/g, while R. undulatum or R. rhaponticum did not exceed 20.4 and 18.1 or 19.8 mg/g and 16.6 mg/g, respectively. Using a broth microdilution method it was found that all of the Rheum spp. extracts were more active against reference strains of Gram-positive bacteria (Staphylococcus spp.) than against those of Gram-negative bacteria (Escherichia coli, Klebsiella pneumoniae and Proteus mirabilis). The strongest inhibitory effect against Staphylococcus spp. was exerted by R. undulatum extract with MIC = 125–250 μg/mL. The moderate in vitro antibacterial activity of R. undulatum suggests that this plant, often used in the European cuisine to improve flavour, may be also important and useful as an alternative or auxiliary medicine remedy in the treatment of uncomplicated superficial infections caused especially by clinically important staphylococci, potentially pathogenic S. aureus or opportunistic S. epidermidis.  相似文献   

11.
Columba livia is an important reservoir and carrier of Cryptococcus neoformans, Cryptococcus uniguttulatus, Cryptococcus laurentii and Cryptococcus albidus. Upper digestive tract of this species is also known as a habitat for Cryptococcus neoformans. Given the increasing clinical interest of this microorganism, 331 swabs from crop and 174 dropping samples from pigeon lofts in Grand Canary Island have been studied. The obtained results show an extensive presence samples 81 positive (24.47%) of Cryptococcus spp. in analysed crops: 32 (9.66%) for C. neoformans, 24 (7.2%) for C. uniguttulatus, 23 (6.9%) for C. albidus and 2 (0.6%) for C. laurentii. In the same way, Cryptococcus spp was also isolated in 82 (47.13%), dropping samples: C. neoformans in 59 (33.9%), C. uniguttulatus, in 9 (5.17%), C. laurentii in 8 (4.59%) and C. albidus in 6 (3.44%) of the investigated samples, respectively. The cryptococcosis produced by species of cryptococci other than C. neoformans has become more important during the last decade, supporting the study on the role of pigeon in the epidemiology of this disease.  相似文献   

12.
Interaction of Bdellovibrio bacteriovorus 100NCJB with bacteria Campylobacter jejuni (strains 1, 2, 3, 4, and 5) and Helicobacter pylori, strain TX30a, was confirmed. The results indicate that lytic activity of bdellovibrios both in liquid media and cells attached to a surface was observed. The potential use of the antimicrobial activity of predatory bacteria for environmental bioprotection and public health is discussed.  相似文献   

13.
Summary  A new species of Eriocaulon, E. epedunculatum (Eriocaulaceae) is described and illustrated from the Western Ghats, India.  相似文献   

14.
Summary  The name Pavetta modesta (Hiern) S. E. Dawson is a later homonym of P. modesta Bremek. Pavetta crystalensis is proposed as a new name.  相似文献   

15.
Using the molecular cytogenetic and RAPD methods of analysis, we studied genomes of 22 cultivated flax varieties and 24 wild species from six sections of the genus Linum L. The chromosome numbers were exactly determined in the karyotypes of all studied species, and all individual chromosomes were identified by the C/DAPI-banding pattern and localization of 26S rDNA and 5S rDNA. B chromosomes were discovered and studied for the first time in species of the section Syllinum Griseb. According to the data obtained, the species studied were divided into eight groups on the basis of similarity of their karyotypes, which corresponded in general to their clustering based on the RAPD results. The systematic positions and phylogenetic relationships of the flax species were verified.  相似文献   

16.
Analysis with the polymerase chain reaction showed that the Khlorofill-4 pea Pisum sativum chlorophyll-deficient mutant with reduced stipules has an altered structure of the COCHLEATA (COCH) gene, carrying a new mutant COCH allele. The phenotype of the mutant was described in comparison with another form having reduced stipules (stipules reduced) and the control. Leaves of the coch mutant are smaller and have other proportions than in the control; stipules are absent from leaves of the first nodes and are narrow, bandlike, or spoonlike at later ontogenetic stages. It was concluded that the cell number in the stipule epidermis is reduced in the st and coch mutants compared to the wild type.  相似文献   

17.
Lactic acid bacteria (LAB) are generally sensitive to hydrogen peroxide (H2O2), Lactobacillus sakei YSI8 is one of the very few LAB strains able to degrade H2O2 through the action of a heme-dependent catalase. Lactobacillus rhamnosus strains are very important probiotic starter cultures in meat product fermentation, but they are deficient in catalase. In this study, the effect of heterologous expression of L. sakei catalase gene katA in L. rhamnosus on its oxidative stress resistance was tested. The recombinant L. rhamnosus AS 1.2466 was able to decompose H2O2 and the catalase activity reached 2.85 μmol H2O2/min/108 c.f.u. Furthermore, the expression of the katA gene in L. rhamnosus conferred enhanced oxidative resistance on the host. The survival ratios after short-term H2O2 challenge were increased 600 and 104-fold at exponential and stationary phase, respectively. Further, viable cells were 100-fold higher in long-term aerated cultures. Simulation experiment demonstrated that both growth and catalase activity of recombinant L. rhamnosus displayed high stability under environmental conditions similar to those encountered during sausage fermentation.  相似文献   

18.
Survey of seven strains determined as Septonema ochraceum (Dothideomycetes, inc. sed.) isolated from pine litter or obtained from public collections revealed three new species, Fusicladium cordae, F. sicilianum (Venturiaceae), Cladophialophora matsushimae (Herpotrichiellaceae) and a cryptic species morphologically identical to Devriesia americana (Teratosphaeriaceae), but phylogenetically distinct. Morphological survey and phylogenetic analysis using nucleotide sequence data from the nuclear ribosomal subunit genes indicate a close relationship within three species colonising pine litter needles, F. cordae, F. pini and F. ramoconidii. F. sicilianum is most related to F. rhodense. C. matsushimae represents a species belonging to one of the lineages of the polyphyletic genus Cladophialophora. None of the strains observed can be classified morphologically as S. ochraceum, of which the type material does not exist.  相似文献   

19.
The genus Cantharellus is known to have a global distribution and to form ectomycorrhizal associations with a diverse set of host plants. Here we describe Cantharellus pseudoformosus as a species new to science with a possible association with Cedrus deodara. ITS and LSU data demonstrated that the material from India is distinct from Cantharellus formosus and other closely related species.  相似文献   

20.
Optimization of conditions for hydroquinone biotransformation into its β-d-glucoside, arbutin, in agitated shoot cultures of Ruta graveolens L. and Hypericum perforatum L. allowed us to obtain a maximum content of this important therapeutic and cosmetic product of 7.8 and 7.2% (dry weight), respectively. These contents are higher than respective values required for standardization of known arbutin-containing plant raw materials according to the European Pharmacopoeia and national pharmacopoeias of European countries.  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