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1.
The floral vasculature in three allied genera,Plagiorhegma, Jeffersoria andAchyls is investigated, and the results are compared with those ofEpimedium andVancouveria which are related closely toPlagiorhegma andJeffersonia. The vasculature in the receptacle ofPlagiorhegma andJeffersonia is similar, but that ofAchlys is much simpler. Slightly different trace patterns are observed in the sepals ofPlagiorhegma andJeffersonia. InJeffersonia, the 3-trace condition leaving 2 or 3 gaps is most frequently observed, but inPlagiorhegma traces of a double nature leaving a single gap are more frequent. The traces to the innermost sepals, petals and stamens are usually of a double nature leaving a single gap in both genera. Regular division and fusion are not observed in the receptacular stele. The vascular differentiation between sepals and petals is more advanced inPlagiorhegma andJeffersonia than inEpimedium andVancouveria. InAchlys, the traces are all staminal and single throughout their course. Two parts recognized in the pistils ofPlagiorhegma, Jeffersonia andAchlys are traversed by independent vasculature. The comparisons of pistil morphology including vasculature ofPlagiorhegma, Jeffersonia, Achlys, Epimedium andVancouveria lead to the interpretation that the pistils are based on the same morphological plan. The probable evolutionary trend in pistil is then suggested in these five genera.  相似文献   

2.
Nuclear DNA variation in Eu-Sorghums   总被引:2,自引:1,他引:1  
R. S. Paroda  H. Rees 《Chromosoma》1971,32(4):353-363
There are significant differences in nuclear DNA amount between Eu-Sorghum species. The DNA variation is considerable. For example Sorghum durra has 63 per cent more DNA than Sorghum roxburghii. Increase in nuclear DNA is accompanied by increase in the mass of the nucleolus and of non-nucleolar material including the chromosomes. The ratio of DNA to non-DNA material is constant between species. The DNA concentration per unit volume at interphase in somatic nuclei and per unit of chromosome length is significantly lower in the wild species S. sudanense and S. virgatum than in the cultivated species S. caudatum, S. conspicuum, S. durra and S. roxburghii. It is suggested that the lower DNA concentration may reflect a lower proportion of heterochromatin relative to euchromatin in the wild as compared with the cultivated forms.  相似文献   

3.
The Ngrol genes, which have high similarity in sequence to the rol genes of Agrobacterium rhizogenes, are present in the genome of untransformed plants of Nicotiana glauca. It is thought that bacterial infection resulted in the transfer of the Ngrol genes to plants early in the evolution of the genus Nicotiana, since several species in this genus contain rol-like sequences but others do not. Plants transformed with the bacterial rol genes exhibit various developmental and morphological changes. The presence of rol-like sequences in plant genomes is therefore thought to have contributed to the evolution of Nicotiana species. This paper focuses on studies of the Ngrol genes in present-day plants and during the evolution of the genus Nicotiana. The functional sequences of several Ngrol genes may have been conserved after their ancient introduction from a bacterium to the plant. Resurrection of an ancestral function of one of the Ngrol genes, as examined by physiological and evolutionary analyses, is also described. The origin of the Ngrol genes is then considered, based on results of molecular phylogenetic analyses. The effects of the horizontal transfer of the Ngrol genes and mutations in the genes are discussed on the plants of the genus Nicotiana during evolution.Seishiro Aoki is the recipient of the Botanical Society Award for Young Scientist, 2002.  相似文献   

4.
Three species of the genus Cacopsylla were collected from Sorbus japonica in Japan. Two of them, Cacopsylla elegans and Cacopsylla sorbicoccinea, are described as new species based on adults and fifth (final) nymphal instars. The third species, Cacopsylla midoriae, is newly transferred from the genus Psylla. The adult of C. midoriae is redescribed and the nymph is described for the first time. A key to the species feeding on S. japonica (adults and nymphs) is provided. The three species were observed to coexist on the same tree of S. japonica in northern Kyushu. Such coexistence of psylloid congeners is uncommon in Japan.  相似文献   

5.
The first report of Aelurostrongylus falciformis (Schlegel 1933) in Fennoscandian badgers is described. Routine parasitological examination of nine Norwegian badgers, at the National Veterinary Institute during 2004 and 2005, identified A. falciformis in the terminal airways of five of the animals. The first stage larvae (L1) closely resembled, in size and morphology, those of Angiostrongylus vasorum (Baillet 1866). The diagnosis for both A. falciformis and A. vasorum is frequently based on the identification of L1 in faeces or sputum. The potential for misclassification of an A. falciformis infection as A. vasorum, where larval identification is the only diagnostic method used, is discussed.  相似文献   

6.
The proboscidean fauna of the middle Miocene of Thailand consists of five taxa, including four elephantoids and one deinothere. The Thai association is dominated by the genera Stegolophodon and Gomphotherium. Stegolophodon is represented by S. nasaiensis and S. praelatidens. The latter species, considered invalid and possibly conspecific with S. latidens, is re‐erected. Its phylogenetic relationships are discussed. The Thai Gomphotherium matches with G. browni from the middle Miocene of Indo‐Pakistan. However, the open nomenclature is employed for the Thai material because it differs from G. browni in terms of curvature of the upper tusk. Intraspecific molar size variation observed in G. cf. browni and Stegolophodon praelatidens is attributed to sexual dimorphism. The Thai proboscidean asssemblage is mainly endemic compared with other contemporaneous Asian faunas although the recognition of Gomphotherium cf. browni denotes faunal affinities with Pakistan. The biostratigraphical implications of the taxa are examined in a regional context. © 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2009, 155 , 703–721.  相似文献   

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8.
该研究以FRPS《中国植物志》全文电子版网站、中国在线植物志(eFlora)网站和国家标本资源共享平台(NSII)网站收录的全部中国桑科植物数据为基础,以部分省的植物志以及正式发表的论文为补充,查找每一个桑科植物的具体分布地点(精确到县一级),并采用地理信息系统技术,以县为空间数据的基本单元,以桑科12属的植物为研究对象,制作属的空间分布图,计算空间相似性系数,分析桑科植物各属的空间多样性及其差异。结果表明:(1)中国桑科植物中桑属的分布最广,橙桑属的分布最狭窄。(2)橙桑属与其他属的空间分布相似性系数均较低(0~0.0444),其中橙桑属与见血封喉属和牛筋藤属的相似性系数均为0,表明橙桑属与其他属的分布几乎没有重叠区;榕属与构属和柘属的空间分布相似性系数分别为0.7394和0.6795,表明这3属的空间分布有较多的重叠区;见血封喉属的分布范围较广,从热带到亚热带地区均有。(3)中国桑科植物属的多样化中心(保护区域)集中在热带和亚热带地区,其中波罗蜜属和葎草属的多样化中心均在云南,鹊肾树属的多样化中心在海南,柘属的多样化中心从热带、南亚热带扩大至中亚热带地区;榕属在中国有98个种,多样化中心分布在甘肃东南部、贵州东北部、云南南部、广西西南部、台湾南部和海南西部;桑属(11个种)的多样化中心分布在重庆南部、湖北南部、湖南西北部、贵州中南部、云南东部和广西西部。研究认为,中国桑科植物属的多样化中心各有特点,基于县的空间分布及多样性研究结果能够具体确定中国桑科植物属的最小保护区域;且该研究结果支持贵州地区是桑属植物的分化中心和过渡中心。  相似文献   

9.
10.
We have sequenced most of the coding region of the gene Dopa decarboxylase (Ddc) in 24 fruitfly species. The Ddc gene is quite informative about Drosophila phylogeny. Several outstanding issues in Drosophila phylogeny are resolved by analysis of the Ddc sequences alone or in combination with three other genes, Sod, Adh, and Gpdh. The three species groups, melanogaster, obscura, and willistoni, are each monophyletic and all three combined form a monophyletic group, which corresponds to the subgenus Sophophora. The Sophophora subgenus is the sister group to all other Drosophila subgenera (including some named genera, previously considered outside the Drosophila genus, namely, Scaptomyza and Zaprionus, which are therefore downgraded to the category of subgenus). The Hawaiian Drosophila and Scaptomyza are a monophyletic group, which is the sister clade to the virilis and repleta groups of the subgenus Drosophila. The subgenus Drosophila appears to be paraphyletic, although this is not definitely resolved. The two genera Scaptodrosophila and Chymomyza are older than the genus Drosophila. The data favor the hypothesis that Chymomyza is older than Scaptodrosophila, although this issue is not definitely resolved. Molecular evolution is erratic. The rates of nucleotide substitution in 3rd codon position relative to positions 1 + 2 vary from one species lineage to another and from gene to gene. Received: 2 June 1998 / Accepted: 3 September 1998  相似文献   

11.
Macrolycus is a genus of net‐winged beetles with 69 species distributed in the eastern Palearctic and northernmost part of the Oriental region. The first molecular phylogeny of Macrolycus was produced using an rrnL + tRNA‐Leu + nad1 mtDNA fragment. The major lineages and species limits were identified with morphology and molecular data. We propose that Cerceros is a subgenus of Macrolycus to enable identification of all adult specimens in the genus without DNA sequencing. Two species groups are proposed in Macrolycus s. str. and six in Cerceros. Additionally, twelve Macrolycus species are newly described from China: M. aquilinus, M. baihualingensis, M. bicolor, M. guangxiensis, M. jianfenglingensis, M. kuatunensis, M. lizipingensis, M. parvus, M. phoeniceus, M. rhodoneurus, M. rosaceus and M. sichuanensis. Macrolycus holzschuhi is proposed to be a junior subjective synonym of M. jeanvoinei. The highest diversity of Macrolycus is found in southern China. The species from the main islands of Japan are placed in two species groups: M. excellens is a sister to remaining species of the M. murzini group and the M. flabellatus group is a monophylum of closely related species in a sister position to the M. bicolor group.  相似文献   

12.
The intragenomic distribution of five retrotransposon families (297, 1731, copia, mdg1 and roo) in the species of the melanogaster complex was studied by comparing results of the Southern blotting technique in males and females with those of in situ hybridization. The degree of structural polymorphism of each family in the different species was also investigated by restriction enzyme analysis. It was found that genomic distribution is a trait that depends on the family and species. The distribution of roo is mainly euchromatic in the four species and 1731 is heterochromatic, but the distribution of families 297, copia and mdg1 is markedly different in the melanogaster and simulans clades. These families were mainly euchromatic in D. melanogaster but heterochromatic in its sibling species. In the simulans clade most copia and mdg1 elements are located on chromosome Y. Differences in genomic distribution are unrelated with structural conservation. The relation of intragenomic distribution to phylogeny, transpositional activity and the role of the host genome are discussed.  相似文献   

13.
The ftsZ gene was cloned from the chromosomal DNA of Brevibacterium lactofermentum by the polymerase chain reaction (PCR) using two oligonucleotides designed from two conserved regions found in most of the previously cloned and sequenced ftsZ genes from other microorganisms. ftsZ is a single-copy gene in corynebacteria and is located downstream from ftsQ and murC, indicating linkage between genes involved in peptidoglycan synthesis (mur genes) and genes involved in cell division (fts genes). The organisation of the cluster is similar to that in Streptomyces and different from those of Escherichia coli or Bacillus subtilis because ftsA is not located upstream of ftsZ. The gene was expressed in E. coli using the T7 expression system; the calculated molecular weight of the expressed protein was 50 kDa. Expression of the B. lactofermentum ftsZ gene in E. coli inhibited cell division and led to filamentation. The ftsZ gene of this organism does not complement ftsZ mutations or deletions in E. coli, when cloned on low or high-copy-number vectors. Received: 14 January 1998 / Accepted: 31 March 1998  相似文献   

14.
The oriental species previously included in the rarely collected genus Nemotha Wood-Mason, 1884 (Mantodea: Iridopterygidae) are revised. N. coomani (Chopard, 1930) and N. mirabilis Beier, 1933 strongly differ from the type species N. metallica (Westwood, 1845) by family-level morphological features, but share a unique type of forefemoral armament with the genera Hapalopeza Stål, 1877 and Amantis Giglio-Tos, 1915, suggesting Nemotha is of a polyphyletic nature. The genus Tricondylomimus Chopard, 1930 is resurrected from synonymy to accommodate T. coomani, T. mirabilis n. comb. and the species which is newly described in this article, T. intermedius n. sp. The monotypic genus Pseudogousa Tinkham, 1937 and its species P. sinensis Tinkham, 1937 are synonymized with Tricondylomimus and T. mirabilis, respectively. The genus Tricondylomimus is placed in Iridopterygidae, while Nemotha is transferred to Hymenopodidae: Anaxarchini.  相似文献   

15.
Summary The glycosylation of flavones in the petals of Melandrium album is shown to be controlled by the genes G, X and A. In the presence of the recessive alleles of these genes, only the aglycone isovitexin (6-C-glucosylapigenin) is found in the petals. The gene G controls the transfer of glucose, the gene X the transfer of xylose to the 7-hydroxyl group of isovitexin. The gene G is epistatic over X. In the presence of the gene A arabinose is coupled to the carbon-carbon bound glucose of isovitexin. In the presence of both G and A, or both X and A the corresponding di-glycosides are formed.The petals of the plants in which all genes for the flavone glycosylation are present in the homozygous recessive form are of a particular phenotype.  相似文献   

16.
Aspergillus nidulans can utilize urea as a sole source of nitrogen but not as a carbon source. Urea is degraded by a urease. Mutation at any one of three genes, ureB, ureC, and ureD, may result in deficient urease activity. The ureB gene is closely linked to ureA, the structural gene for the urea transport protein. The heat lability of a ureB revertant strain, intragenic complementation tests, and the linkage of ureB to ureA suggest that ureB is the urease structural gene. The ureD gene is probably involved in the synthesis or incorporation of a nickel cofactor essential for urease activity. The function of the ureC gene is not known. Urease is not induced but is subject to nitrogen regulation. The urease activities of ammonium-derepressed mutants show that the effector of nitrogen regulation is more likely to be glutamine than ammonium. When glutamine is present in the medium, urease appears to be inactivated by some means which does not involve a newly synthesized protease or a direct interaction between glutamine and urease.  相似文献   

17.
18.
Summary A mutation pgi1 in the yeast Saccharomyces cerevisiae conferring deficiency of the glycolytic enzyme glucose 6-phosphate isomerase is characterised genetically. The mutation segregates 2+:2- in tetrads from diploids heterozygous for the mutant phenotype. The mutation is semi-dominant and is located on the right arm of chromosome II in the order: tsm134-lys2-pgi1-tyr1 approximately 15 map units from tyr1. The mutation pgi1 defines the structural gene of glucose 6-phosphate isomerase and can be suppressed intragenically giving revertants that have an unstable enzyme. In one temperature-sensitive revertant no enzyme activity in excess of the mutant level could be detected although fructose 6-phosphate was converted to glucose 6-phosphate in vivo. The suppressor locus in this revertant is dominant and is unlinked to the pgi1 locus.  相似文献   

19.
J. Moravec 《Plant Ecology》1985,59(1-3):39-45
The 10 Fagion associations bound to the western part of Czechoslovakia are conditioned both ecologically and chorologically in their species differentiation as well as geographical distribution. The division of the alliance into suballiances follows primarily the ecological phenomena. Within the Eu-Fagenion the associations form 3 groups conditioned by ecological factors.The Tilio platyphylli-Fagetum, Tilio cordatae-Fagetum, Melico-Fagetum and Carici pilosae-Fagetum represent associations of the submontane belt. The Tilio platyphylli-Fagetum is characterized by overlapping of Fagion and Carpinion species and by the absence of any Dentaria species due to chorological causes. The Tilio cordatae-Fagetum does not show any chorological phenomena in the species composition, however, it is limited to central, southern and western Bohemia only. The Melico-Fagetum is characterized by dominant Melica uniflora which is absent in the western and southern part of Bohemia. The Melico-Fagetum has even a more limited distribution occurring in northern and eastern Bohemia and in northern and central Moravia only. The Carici pilosae-Fagetum is characterized by Carex pilosa (dominant), Cephalanthera longifolia and Euphorbia amygdaloides; it is confined to the Carpathian province.The Dentario enneaphylli-Fagetum, Dentario glandulosae-Fagetum and Violo reichenbachianae-Fagetum represent a group of vicarious associations of the montane belt. The Dentario enneaphylli-Fagetum occurs mainly in the geographical province eská vysoina. Its eastern limit lies in the westernmost part of the Carpathian province where it forms a special subassociation and contacts the Dentario glandulosae-Fagetum. The latter association is characterized primarily by Dentaria glandulosa, a Carpathian endemic species. The Violo reichenbachianae-Fagetum is conditioned chorologically by the absence of any Dentaria species; it occurs in the mountains Kruné hory and Doupovské hory only.The Festuco-Fagetum is the single representant of the third group conditioned mainly by ecological factors.Nomenclature of species follows rothmaler et al. (1970).  相似文献   

20.
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