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961.
The fossil record and molecular data show that the evolutionary history of arbuscular mycorrhizal fungi (Glomales) goes back at least to the Ordovician (460 million years ago), coinciding with the colonization of the terrestrial environment by the first land plants. At that time, the land flora only consisted of plants on the bryophytic level. Ribosomal DNA sequences indicate that the diversity within the Glomales on the family and genus level is much higher than previously expected from morphology-based taxonomy. Two deeply divergent lineages were found and described in two new genera, Archaeospora and Paraglomus, each in its own family. Based on a fast-growing number of available DNA sequences, several systems for molecular identification of the Glomales within roots have been designed and tested in the past few years. These detection methods have opened up entirely new perspectives for studying the ecology of arbuscular mycorrhiza. 相似文献
962.
从湖南、江西两地铀矿床区采集土壤样品 13份 ,用选择性培养基从 10 -3 稀释的平板中分离到卵黄反应阳性菌 2 38株 (其中xw1,xw2 无该菌 )。从中筛选 8株 ,经纯化培养 ,对 8株进行了显微镜和电镜的形态观察 ,其形态为典型的杆菌 ,大小为 1.2~ 1.4μm× 2 .6~ 3.4μm ,芽孢为椭圆或橄榄果实形。没有孢囊和伴孢晶体 ,周生鞭毛。生理生化分析结果证明 ,8株均为典型的蜡状芽孢杆菌 (Bacilluscereus)。 相似文献
963.
LORENZO PERUZZI NICODEMO GIUSEPPE PASSALACQUA 《Botanical journal of the Linnean Society. Linnean Society of London》2008,157(4):763-774
A morphometric study on five populations of the Onosma echioides complex was carried out through univariate analysis, principal coordinate analysis and cluster analysis (the unweighted pair‐group method with arithmetic mean; UPGMA). In consideration of the quantitative morphological variability, of the known karyological homogeneity and of the allopatric distribution of the taxa, we propose here to treat this complex as a single species subdivided in four subspecies. The names O. angustifolia Lehm., O. canescens J. et C. Presl, O. dalmatica Scheele, O. echioides var. columnae Lacaita, O. echioides var. veronensis Lacaita and O. javorkae Simonkai are typified. The new combinations O. echioides subsp. angustifolia (Lehm.) Peruzzi & N. G. Passal., O. echioides subsp. canescens (J. et C. Presl) Peruzzi & N. G. Passal. and O. echioides subsp. dalmatica (Scheele) Peruzzi & N. G. Passal. are proposed. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 157 , 763–774. 相似文献
964.
The aploactinid fish Ptarmus gallus is redescribed and recorded from the Gulf of Suez (Egypt) for the first time. The species is apparently endemic to the Red Sea. Identification keys to the genera of aploactinid fishes, and to species of the genus Ptarmus are presented. 相似文献
965.
Extensive studies during the last 20 years have demonstrated that enzyme phenotypes, especially those of esterases, are species-specific for Meloidogyne and can be used as reliable taxonomic characters for identification of most major and several minor species of this genus. Recent progress in electrophoretic procedures and advanced computer technology have made available automated electrophoretic apparati that can process very thin polyacrylamide slab gels on which the phenotypes of two or more enzymes can be revealed from the protein extract of a single Meloidogyne female. Presently, such apparati facilitate objective species identification. They also are convenient for performing routine field surveys to determine the relative distribution of major Meloidogyne species, conducting population dynamics studies in the field and in microplots, and testing the purity of greenhouse cultures. 相似文献
966.
A. M. Figueiras M. T. González-Jaén M. Candela 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1990,79(5):686-692
Summary The spontaneous interchange polymorphism of rye cultivar Ailés is composed, as can be deduced from the chromosomal identification of the interchanges analyzed, of several different reciprocal translocations in which the chromosomes of its haploid complement are involved with a similar frequency, except for chromosomes 4R and 6R. Several features of chromosome behavior at metaphase I, such as configuration and orientation of quadrivalents and frequency of chiasmata, were analyzed in structural heterozygotes for different interchanges. The two main factors affecting the orientation of quadrivalents at metaphase I proved to be the morphology of these chromosome associations at metaphase I and, in particular, the frequency of bound chromosome arms that they showed. A genotypic control of alternate orientation of quadrivalents independent of chiasmata frequency was not detected. In addition, the frequency of alternate orientation shows no relation to the fitness. Possible evolutionary implications of the results obtained are discussed. 相似文献
967.
介形类个体发育过程中壳体形状及各种构造的多态性,以及各种外界环境因素对分形类壳体各种分类特征形态变化的影响是十分明显的。该文较系统地阐述了在介形类个体发育中壳体形状、大小、肌痕、边缘毛细管带、边庭、铰合构造及纹饰的变化,并介绍了成年期雌、雄性壳体及左、右壳瓣在形态上的差异;列举了环境因素(主要是水体温度、含盐度、深度)对介形类壳体各分类特征形态变化的影响。基于以上事实,提出了古生物工作者在介形类化石鉴定中应注意的一些问题并讨论了某些描述术语的具体标准。 相似文献
968.
B. Vosman P. Arens W. Rus-Kortekaas M. J. M. Smulders 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1992,85(2-3):239-244
Summary This paper describes the use of oligonucleotide probes to reveal highly polymorphic DNA regions in pomato. With a (GATA)4 probe the level of polymorphism detected is high enough to identify all 15 tomato cultivars used in this study. Individual plants of one cultivar all showed the same cultivar-specific DNA-finger-print. In an F2-population of self-fertilized cv. Sonatine, GATA-containing loci segregated in a Mendelian (31) fashion. Experiments with in-vitro propagated plant material showed that the DNA-fingerprints are not affected by tissue-culture procedures. This indicates that changes in the genetic integrity, which often accompany in-vitro propagation (somaclonal variation), are not extended to the DNA detected with the (GATA)4 probe. The relative high stability and the Mendelian segregation of (GATA)4-derived DNA-fingerprints make them ideally suited for identification of tomato cultivars. 相似文献
969.
T D Holland 《American journal of physical anthropology》1991,85(2):221-227
The proximal end of the human tibia is sexually dimorphic. Tibial condyles from 100 individuals in the Hamann-Todd Collection were measured. Regression equations retrodicted known sex with 86-95% accuracy. A test sample of 20 individuals also from the Hamann-Todd Collection was classified with 85-100% accuracy. A sample of 20 prehistoric individuals provisionally sexed by using crania and innominate bones was classified with 85-100% agreement. Thus, the proximal tibia may be useful in determining the sex of a skeleton. 相似文献
970.
M. Mazor M. Harel S. Levsky E. Dunkelblum 《Entomologia Experimentalis et Applicata》1991,60(2):167-172
Capillary gas chromatography indicated the presence of (Z)-7-dodecenyl alcohol and (Z)-7-dodecenyl acetate in the abdominal tip extracts of female Cornutiplusia circumflexa (L.) (Lepidoptera: Noctuidae: Plusiinae) moths. Gas chromatography combined with mass spectrometry and dimethyl disulfide derivatization confirmed the structure of these two principal pheromone components. In a flight-tunnel bioassay, a 5:1 blend of alcohol and acetate elicited the complete courtship sequence by males. The response was comparable to that evoked by a live virgin female, but males spent significantly longer time at calling females than at the synthetic source. The 5:1 blend was also attractive to male C. circumflexa in the field, as indicated by catches in traps baited with this mixture. (Z)-7-dodecenyl alcohol alone was slightly attractive whereas (Z)-7-dodecenyl acetate alone was completely inactive. C. circumflexa is the first reported Plusiinae species which utilizes (Z)-7-dodecenyl alcohol as the major pheromone component. 相似文献