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 31 毫秒
1.
In Silene pratensis three loci (g, gl and fg) control the glycosylation of isovitexin. Three alleles are known for both the g-locus (g, g G and g X ) and the gl-locus (gl, gl A and gl R ); for the fg-locus there are only two alleles (fg and Fg). The distribution of these alleles over 285 European populations of S. pratensis has been investigated. It was concluded that there are three different chemical races within S. pratensis in Europe. The first race contains the populations in western and southern Europe and displays high frequencies of g G , gl and fg. The frequencies of g G and gl R are very high in the second chemical race, which can be found in the USSR, Scandinavia and eastern Poland. The third chemical race occurs in central Europe and in this race the frequencies of both g and gl R are high, Fg has low to moderate frequencies in the second and third groups. The alleles gl A and g X are seldom found in S. pratensis, but are present in the closely related S. dioica. They do occur with low frequencies in some populations of S. pratensis, possibly as a result of hybridization with S. dioica.  相似文献   

2.
We present a critical checklist of freshwater fish species found so far in the countries of Armenia, Azerbaijan and Georgia. In total 119 freshwater fishes are recorded. There are 40, 86 and 96 species currently known for Armenia, Azerbaijan and Georgia respectively. From these 119 species, seven are endemic and seven species are alien. From the alien species, only three (Carassius gibelio, Gambusia holbrooki and Pseudorasbora parva) can be considered as widespread and invasive. There are four species (Gasterosteus aculeatus, Gobio artvinicus, Perca fluviatilis and Salmo gegarkuni) that are translocated within the region. Seven species are confirmed or recorded for the first time including G. artvinicus and Oxynoemacheilus veyselorum for Armenia, Azerbaijan and Georgia, Capoeta kaput and Rhinogobius lindbergi for Azerbaijan and Georgia, Capoeta razii for Azebaijan, Oxynoemacheilus cemali and Squalius agdamicus for Georgia. In this checklist, Acipenser colchicus is treated as a synonym of Acipenser persicus. Sand smelts of the Black and Caspian Sea basin are identified as Atherina caspia and Clupeonella caspia is treated as a synonym of Clupeonella cultriventris. Coregonus sevanicus is listed as Coregonus sp. until the situation of Sevan whitefish is better understood. Capoeta sevangi and Capoeta ekmekciae are synonyms of Capoeta capoeta. The fish often identified as Capoeta capoeta gracilis from rivers south of the Kura most likely belong to C. razii. The Black and Caspian Sea Rutilus populations are treated as conspecific, therefore Rkutum is a junior synonym of Rfrisii. Oxynoemacheilus veyseli is valid as Oveyselorum. We list the alien Rhinogobius species as Rlindbergi, however the name is provisional and needs further confirmation. All Squalius species from the Kura River drainage are identified as Sagdamicus, however in the Aras, it is replaced by S. turcicus. Squalius orientalis is treated as a valid species restricted to the eastern Black Sea basin. The four forms of Lake Sevan trout (Salmo ischchan, Sgegarkuni, S. danilewskii and Saestivalis) are treated as valid species, two of them (Sischchan and Sdanilewskii) are extinct. Rutilus sojuchbulagi from Azerbaijan is also extinct.  相似文献   

3.
4.
该文报道了广西维管植物新记录9种,即刻节润楠(Machilus cicatricosa S. Lee)、四瓣马齿苋(Portulaca quadrifida L.)、腺果藤(Pisonia aculeata L.)、阳春山龙眼(Helicia yangchunensis H. S. Kiu)、小鹿藿[Rhynchosia minima(L.) DC.]、白皮素馨(Jasminum rehderianum Kobuski)、宿苞厚壳树(Ehretia asperula Zoll. et Mor.)、卵叶线柱兰(Zeuxine ovalifolia L. Li&S. J. Li)和羽状穗砖子苗(Cyperus javanicus Houtt.)。文中还提供了识别特征和彩色照片,并列出了每个种的标本引证及地理分布。  相似文献   

5.
Summary Four gal negative mutations, which affect the expression of the gal operon severely as described in the preceding paper (Saedler et al.), are characterized as insertions of DNA by CsCl density gradient centrifugation of transducing phages carrying the mutations and by electron microscopy of hybrid DNA molecules in which the insertion forms a singlestranded loop.Mutation galOP in 308 is shown by both procedures to be about twice as large as the three other insertions, which are similar in size. The length of the insertions as determined by electron microscopy corresponds to about 1500 nucleotide pairs galOP in 308 and 800, 700, and 700 nucleotide pairs for galOP in 128, 141, and 306 respectively. Single-stranded regions are seen in hybrid molecules prepared between DNAs from galOP in 306 and 128, 141 or 308 as well as from galOP in 308 and 128. No such single-stranded regions are observed in hybrid molecules between DNAs from galOP in 128 and 141.Thus, at least three of the four insertions are not identical.  相似文献   

6.
Summary Unequal crossing over occurs in females heterozygousw a /w a4 such that a deficiency and duplication can be recovered regularly. A triplication was also found following crossing over in the homozygous duplication.Genetic analysis of the duplication showed that of the several knownw loci only thew e andsp-w loci are duplicated.By means of crossing overw e andsp-w were introduced separately into the left half of the duplication andw e into the right half. The phenotypic consequences of such substitutions are interpreted in terms of the loci which are included in specific functional units or genes. They suggest thatw e andsp-w are in distinctive functional units.The fact that these duplications and deficiencies are without obvious affect on salivary gland band morphology suggests that the gene loci constitute only a small portion of the band structure.  相似文献   

7.
Insect midgut proteases are known to be regulated by plant protease inhibitors. In the present study, the antinutritional effects of a variety of seed extracts against Periplaneta americana (Linnaeus) (Dictyoptera: Blattidae) midgut proteases are assessed in vitro and in vivo. Bioassays are conducted by allowing P. americana to feed on diets incorporated with the tested seed extracts. Low survival rates are recorded on a diet incorporated with seed powders of Ricinus communis (10%), Glycine max (30%), Datura alba (50%) and Mucuna pruriens (50%). Proteolytic and residual proteolytic activities are highly inhibited by the four seed extracts. Electrophoretic analysis shows that the majority of P. americana midgut protease isoforms are inhibited by the four seed extracts in vivo as well as in vitro. The midgut physiology of P. americana is affected by the seed extracts of D. alba, M. pruriens and Sapindus laurifolius, by over synthesising or changing mobilities of existing protease isoforms. Furthermore, some key proteases in P. americana midgut are involved in the regulation of other protease isoforms. These results suggest that seed extracts from the above plants are potential sources of plant protease inhibitors for managing economically important crop pests.  相似文献   

8.
A locally severe crown disease of exotic plantation Eucalyptus trees has been recorded periodically in New Zealand since 1986. Symptoms include leaf spots, petiole infection and twig and small branch lesions. Outbreaks of disease are episodic and individual trees may show marked variation in crown symptoms ranging from unaffected to total defoliation. Two previously unknown species of Phytophthora are associated with the disease. These are described and formally designated here as P. captiosa, from Eucalyptus botryoides and E. saligna; and P. fallax, from E. delegatensis, E. fastigata, E. nitens and E. regnans. Both P. captiosa and P. fallax have non-papillate, non-caducous sporangia and both are self-fertile. Phylogenetic analysis on the basis of ITS rDNA sequence data indicates they are closely related to each other but evolutionarily distant from the majority of described Phytophthora taxa. They share a common ancestor with another assemblage of Phytophthora lineages that includes P. insolita, P. macrochlamydospora and P. richardiae. Sporulation of P. captiosa and P. fallax has not been observed in the field. The mode of infection and spread of these non-caducous Phytophthora species in the eucalypt tree canopy remains unknown. This issue, and the possible geographic origins of these two Phytophthora species are discussed.  相似文献   

9.
The phylogenetic relationships and generic assignments of ‘Ochlerotatus’ and related taxa of uncertain taxonomic position in the classification of Aedini previously proposed by the authors in 2004 and 2006 are explored using 297 characters from eggs, fourth‐instar larvae, pupae, adults and immature habitat coded for 158 exemplar species. The ingroup comprises 54 species and the outgroup includes four non‐aedine species and 100 aedine species, 21 of which were previously classified as incertae sedis. Data are analysed in a total‐evidence approach using implied weighting. The analysis produced 158 most parsimonious cladograms. The strict consensus tree (SCT) corroborates the monophyly of the 30 generic‐level taxa recognized previously that are included in the analysis. Overall, the results show remarkable congruence with those obtained previously despite differences in the taxa and morphological characters analysed in this and the two previous studies. All species of Ochlerotatus s.s., subgenus ‘Ochlerotatussensu auctorum, Geoskusea, Levua, Pseudoskusea and Rhinoskusea included in the analysis fall within a single clade that is treated as genus Ochlerotatus; thus, the last four taxa are restored to their previous subgeneric rank within this genus. Nine additional subgenera, of which four are new, are proposed for monophyletic clades of Ochlerotatus species based on the strength of character support and application of the principle of equivalent rank. Acartomyia stat. nov. , Culicelsa stat. nov. , Gilesia stat. nov. , Protoculex stat. nov. and Chrysoconops stat. nov. are resurrected from synonymy with Ochlerotatus; and Empihals subgen. nov. (type species: Culex vigilax Skuse), Pholeomyia subgen. nov. (type species: Aedes calcariae Marks), Buvirilia subgen. nov. (type species: Aedes edgari Stone & Rosen) and Sallumia subgen. nov. (type species: Aedes hortator Dyar & Knab) are described as new. The sister group of Ochlerotatus includes a number of species that were previously regarded as incertae sedis in ‘Oc. (Finlaya)’ and ‘Oc. (Protomacleaya)’. Based on previous observations, refined relationships and new character support, three additional genera are recognized for species previously included in ‘Finlaya’, i.e. Danielsia stat. nov . (type species: Danielsia albotaeniata Leicester), Luius gen. nov. (type species: Aedes fengi Edwards) and Hopkinsius gen. nov. (type species: Aedes ingrami Edwards). Additionally, Alloeomyia subgen. nov. (type species: Culex pseudotaeniatus Giles) and Yamada subgen. nov. (type species: Aedes seoulensis Yamada) are introduced as subgenera of Collessius and Hopkinsius, respectively. As is usual with generic‐level groups of Aedini, the newly recognized genera and subgenera are polythetic taxa that are diagnosed by unique combinations of characters. The analysis corroborates the previous observation that ‘Oc. (Protomacleaya)’ is a polyphyletic assemblage of species. © 2008 The Linnean Society of London, Zoological Journal of the Linnean Society, 2008, 153 , 29–114.  相似文献   

10.
The sect.Cortusina (Dc.)Harv. s.l. is divided into the sectt.Cortusina (Dc.)Harv. s. str. andReniformia (Knuth)Dreyer, comb. nov.,P. cortusifolium L'Hérit.,P. crassicaule L'Hérit.,P. echinatum Curt.,P. magenteum J. J. A. Van der Walt, andP. sibthorpifolium Harv. remain in the sect.Cortusina s. str., while the speciesP. album J. J. A. Van der Walt,P. dichondrifolium Dc.,P. odoratissimum (L.)L'Hérit.,P. reniforme Curt., andP. sidoides Dc. are removed from the sect.Cortusina s.l. and included in the revised sect.Reniformia. Both sections are well characterized by morphological, anatomical, karyological and palynological features. The chromosomes ofCortusina s. str. are small and based upon x = 11; those ofReniformia are larger and based upon x = 8. The size and surface sculpture of the pollen grains differ markedly between the two sections. Flavones and hydrolysable tannins occur in sect.Reniformia, but are absent in sect.Cortusina s. str. After hydrolysis hydroxybenzoic acids, which are present in large amounts inReniformia, occur only in traces inCortusina. The two sections also occupy distinctly different geographical areas. A close relationship between sect.Reniformia and some species of sect.Ligularia (Sweet)Harv. is indicated by the occurrence of artificial hybrids.  相似文献   

11.
This paper presents new species, combinations, national reports and host records for the South African rust fungi (Uredinales/Pucciniales). Endophyllum mpenjatiense on cf. Hibiscus sp. (Malvaceae), Phakopsora combretorum (anamorph Uredo combreticola) on the new host Combretum apiculatum (Combretaceae) and Uredo sekhukhunensis on Ziziphus mucronata (Rhamnaceae) are described as new species. Dietelia cardiospermi and E. metalasiae are proposed as new combinations to replace Aecidium cardiospermi on Cardiospermum halicacabum (Sapindaceae) and A. metalasiae on Metalasia spp. (Asteraceae), respectively. Four species are new records for South Africa: Crossopsora antidesmae-dioicae on Antidesma venosum (Euphorbiaceae), Phakopsora ziziphi-vulgaris on Z. mucronata, and Uromyces cypericola and Puccinia subcoronata, both on a new host, Cyperus albostriatus (Cyperaceae). The record of P. subcoronata is the first one from outside the New World. Puccinia scirpi is reported as a possible addition to the South African rust fungi. New host records and observations are presented for Pucciniastrum agrimoniae that is recorded on two new host genera and species, Cliffortia odorata and Leucosidea sericea (Rosaceae), Uromyces cypericola whose urediniospores are described for the first time, Phakopsora stratosa in that spermogonia and Uredo-like aecia were discovered, and for Sphaerophragmium dalbergiae in that characters of the urediniospores are re-evaluated. A lectotype is selected for Aecidium garckeanum and spermogonia are reported for this rust for the first time. The rust fungi of Ehrharta (Poaceae) are discussed and critically evaluated in the light of spore morphology and host species.  相似文献   

12.
13.
The Actinobacteria constitute one of the main phyla of Bacteria. Presently, no morphological and very few molecular characteristics are known which can distinguish species of this highly diverse group. In this work, we have analyzed the genomes of four actinobacteria (viz. Mycobacterium leprae TN, Leifsonia xyli subsp. xyli str. CTCB07, Bifidobacterium longum NCC2705 and Thermobifida fusca YX) to search for proteins that are unique to Actinobacteria. Our analyses have identified 233 actinobacteria-specific proteins, homologues of which are generally not present in any other bacteria. These proteins can be grouped as follows: (i) 29 proteins uniquely present in most sequenced actinobacterial genomes; (ii) 6 proteins present in almost all actinobacteria except Bifidobacterium longum and another 37 proteins absent in B. longum and few other species; (iii) 11 proteins which are mainly present in Corynebacterium, Mycobacterium and Nocardia (CMN) subgroup as well as Streptomyces, T. fusca and Frankia sp., but they are not found in Bifidobacterium and Micrococcineae; (iv) 8 proteins that are specific for T. fusca and Streptomyces species, plus 2 proteins also present in the Frankia species; (v) 13 proteins that are specific for the Corynebacterineae or the CMN group; (vi) 14 proteins only found in Mycobacterium and Nocardia; (vii) 24 proteins unique to different Mycobacterium species; (viii) 8 proteins specific to the Micrococcineae; (ix) 85 proteins which are distributed sporadically in actinobacterial species. Additionally, many examples of lateral gene transfer from Actinobacteria to Magnetospirillum magnetotacticum have also been identified. The identified proteins provide novel molecular means for defining and circumscribing the Actinobacteria phylum and a number of subgroups within it. The distribution of these proteins also provides useful information regarding interrelationships among the actinobacterial subgroups. Most of these proteins are of unknown function and studies aimed at understanding their cellular functions should reveal common biochemical and physiological characteristics unique to either all actinobacteria or particular subgroups of them. The identified proteins also provide potential targets for development of drugs that are specific for actinobacteria.Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users.  相似文献   

14.
New synonymy and distribution records for the genus Macromitrium Brid. in sub-Saharan Africa are presented. Seven names are placed in synonymy, reducing the number of accepted taxa for Macromitrium in sub-Saharan Africa to 33. Macromitrium anomodictyon Cardot was found to be conspecific with M. serpens (Bruch ex Hook. & Grev.) Brid.; M. mauritianum Schwägr. and M. sanctae-mariae Renauld & Cardot are placed in synonymy with M. subtortum (Hook. & Grev.) Schwägr. and M. belangeri Müll.Hal., M. seriatum Paris & Broth., M. bequaertii Thér. & Naveau and M. trollii Dixon in Herz. are all placed in synonymy with M. sulcatum (Hook.) Brid. subsp. sulcatum. The precise lectotypification is implemented for six species within the genus. Macromitrium chloromitrium (Besch.) Wilbraham and M. orthostichum Nees ex Schwägr. are reported new to Tanzania and M. chloromitrium new to continental Africa.  相似文献   

15.
The Chinese species of the subgenus Microchelonus Szépligeti of the genus Chelonus Panzer with the female carapace having an incised apex in dorsal view and/or in posterior view are revised. Two new species, Chelonus (Microchelonus) rhagius sp. n. and Chelonus (Microchelonus) tobiasi sp. n. are described. Chelonus (Microchelonus) elegantulus Tobias and Chelonus (Microchelonus) volgensis Tobias are recorded in China for the first time.  相似文献   

16.
A taxonomic revision of Tectaria from New Caledonia is presented here based on a thorough study of herbarium specimens from New Caledonia and adjacent Pacific islands. Six species of Tectaria are presently recognized in New Caledonia. Tectaria kouniensis and T. pseudosinuata are reduced to synonyms of T. dissecta and T. sinuata, respectively. The morphological limit between T. seemannii and T. sinuata and the confused specimen citations in previous accounts are clarified. Apart from T. dissecta, the other five species, i.e. T. lifuensis, T. moorei, T. seemannii, T. sinuata and T. vieillardii, are mainly distributed in New Caledonia, with only T. seemannii and T. sinuata recently reported also from Vanuatu. A key to species, typification of accepted names and relevant synonyms, and brief comments on the relationships of species are provided.  相似文献   

17.
Aquatic plants comprise few species worldwide, yet introductions of nonindigenous hydrophytes represent some of the most severe examples of biological invasions. Often innocuous in their indigenous regions, many aquatic plant species have caused extreme ecological and economic consequences when introduced into nonindigenous habitats. Typically, aquatic plant invasions are unnoticed or overlooked until they are perceived as problematic. By then, plants are virtually impossible to eradicate and negative ecological impacts caused by their spread into natural communities are irreparable. We present criteria to facilitate decisions whether a species should be characterized as nonindigenous or invasive. Historical data are used to clarify methods of introduction, avenues and means of dispersal, and extent of invasiveness of the following aquatic plants in southern New England: Acorus calamus, Butomus umbellatus, Cabomba caroliniana, Callitriche stagnalis, Egeria densa, Hydrilla verticillata, Limnobium spongia, Marsilea quadrifolia, Myriophyllum aquaticum, Myriophyllum heterophyllum, Myriophyllum spicatum, Najas minor, Najas guadalupensis, Nasturtium officinale, Nymphoides peltata, Potamogeton crispus, Trapa natans and Veronica beccabunga.  相似文献   

18.
The family Neckeraceae is composed of three distinct clades, of which two, i.e. the Neckera and Thamnobryum clades, are well defined. The third clade, consisting of species belonging to Caduciella, Curvicladium, Handeliobryum, Himantocladium, Homaliodendron, Hydrocryphaea, Neckera, Neckeropsis, Pinnatella, Shevockia and Taiwanobryum, is the focus of this study. Based on sequence data from the trnS-rps4-trnT-trnL-trnF plastid cluster and the rpl16 intron as well as from nuclear ITS1&2, the phylogenetic relationships of these genera are reconstructed. The nearest relatives of this clade are resolved shedding more light on the evolution of the family. The generic composition of the clade and its individual genera are discussed; polyphyly requires redefinition of Pinnatella, Neckeropsis and Homaliodendron. The positions of Touwia and Homalia within the family are addressed in an additional analysis based on more extensive sequence data, and the corresponding new combinations are made. Several further taxonomic changes are proposed, including Circulifolium gen. nov., comprising the former Homaliodendron exiguum and H. microdendron.  相似文献   

19.
The COT1 and ZRC1 genes of Saccharomyces cerevisiae are structurally related dosage-dependent suppressors of metal toxicity. COT1 confers increased tolerance to high levels of cobalt; ZRC1 confers increased tolerance to high levels of zinc. The two genes are not linked and have been mapped; COT1 to chromosome XV and ZRC1 to chromosome XIII. Phenotypes related to metal homeostasis have been examined in strains with varied COT1 and ZRC1 gene doses. Overexpression of COT1 confers tolerance to moderately toxic levels of zinc and ZRC1 confers tolerance to moderately toxic levels of cobalt. Strains that carry null alleles at both loci are viable. The metal-hypersensitive phenotypes of mutations in either gene are largely unaffected by changes in dosage of the other. COT1 and ZRCI function independently in conferring tolerance to their respective metals, yet the uptake of cobalt ions by yeast cells is dependent on the gene dosage of ZRC1 as well as of COT1 Strains that overexpress ZRC1 have increased uptake of cobalt ions, while ZRCI null mutants exhibit decreased cobalt uptake. The defects in cobalt uptake due to mutations at COT1 and ZRC1 are additive, suggesting that the two genes are responsible for the majority of cobalt and zinc uptake in yeast cells. The function of either gene product seems to be more important in metal homeostasis than is the GRR1 gene product, which is also involved in metal metabolism. Mutations in the GRR1 gene have no effect on the cobalt-related phenotypes of strains that have altered gene dosage of either COT1 or ZRC1.  相似文献   

20.
Studies on the bacterial diseases of Sudan crops   总被引:2,自引:0,他引:2  
New records are presented of bacterial diseases affecting the following weed plants: Heliotropium sudanicum, Rhynchosia memnonia, Vigna radiata, V. pubigera, Euphorbia acalyphoides and Phyllanthus niruri. Bacterial leaf blight of pigeon pea (Cajanus cajan) caused by Xanthomonas phaseoli f. cajani is reported for the first time from the Sudan. The causal bacteria, all of which belong to the genus Xanthomonas, are compared with related pathogens. The differences between these bacteria are considered of little diagnostic value. Pathogenically, they can be separated into three groups: (i) the Heliotropium pathogen; (ii) the bacteria affecting leguminous plants; and (iii) the bacteria affecting species of the family Euphorbiaceae. Because of the diversity in opinion on speciation in the genus Xanthomonas, two alternative proposals are put forward. In the first, Xanthomonas is considered a monotypic genus with X. campestris as the sole species. The pathogens reported in this work from previously unrecorded hosts, which proved to differ in pathogenicity from established ones, are considered to be new formae speciales. These are X. campestris f.sp. heliotropii from H. sudanicum, X. campestris f.sp. rhynchosiae from R. memnonia, X. campestris f.sp. vigna-radiatae from V. radiata, X. campestris f.sp. euphorbiae from E. acalyphoides and X. campestris f.sp. phyllanthii from P. niruri. The organism from V. pubigera is accordingly identified as X. campestris f.sp. vignicola. Other bacteria used for comparison are also reduced to ff.sp. of X. campestris. The other proposal is to lump together pathogens with overlapping host ranges in a single species that comprises a number of ff.sp. differing in pathogenicity. Thus the bacteria from leguminous plants are all considered to belong to X. phaseoli as previously suggested by Sabet. New ff.sp. are created for the pathogens from R. memnonia (X. phaseoli f.sp. rhynchosiae), and V. radiata (X. phaseoli f.sp. vigna-radiatae). The organism from V. pubigera is identified in this case as X. phaseoli f.sp. vignicola. The bacteria from members of the Euphorbiaceae are considered to belong to X. ricini on priority grounds. X. cassavae and X. poinsettiaecola which have been used for comparison are reduced to the ff.sp. X. ricini f.sp. cassavae and f.sp. poinsettiaecola respectively. Two new ff.sp. are created: for E. acalyphoides pathogen, X. ricini f.sp. euphorbiae and for P. niruri pathogen, X. ricini f.sp. phyllanthii. The creation of a new species (X. heliotropii sp.nov.) is proposed for the Heliotropium pathogen. The present study shows that many weed plants may be affected with new bacterial strains that can also infect cultivated crops.  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