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1.
SYNOPSIS. Death rates of A/J and CF1 female mice 4 weeks and 6 months of age were compared after the mice were infected with Plasmodium berghei NK65C deme (population) and NK65RR deme. Death rates were compared also when female A/J retired breeder mice were infected with blood passages 18 and 40 of NK65C. NK65C was found to be less virulent than NK65RR. The 40th blood passage of NK65C was more virulent than the 18th passage, but still not as virulent at the NK65RR deme. A/J retired breeders were clearly more resistant to infection than 4 week old A/J mice, while little difference was found in the different age groups of the CF1 mice.  相似文献   

2.
基于丫瓣兰Ypsilorchis fissipetala (Finet)Z.J.Liu,S.C.Chen &L.J.Chen(基名为裂瓣羊耳蒜Liparis fissipetala Finet)建立了兰科新属--丫瓣兰属Ypsilorchis Z.J.Liu,S.C.Chen&.J.Chen.新属与羊耳蒜属Liparis的区别点为:新属有两个粉蜡质花粉团:每个花粉团具1个多少有弹性的花粉团柄;花瓣二深裂;叶具强烈波状的边缘,其先端有一个长达1 mm的芒尖.这些特征表明了其与羊耳蒜亚族Liparidinae有明显的差别,为此,建立了一个新的亚族--丫瓣兰亚族Ypsilorchidinae Z.J.Liu,S.C.Chen &L.J.Chert.  相似文献   

3.
A new orchid genus, Ypsilorchis Z. J. Liu, S. C. Chen & L. J. Chen, is established based on Ypsilor-chis fissipetala (Finet) Z. J. Liu, S. C. Chen & L. J. Chen (basionym: Liparis fissipetala Finet). The new genus differs from Liparis and its allies by having two granular-waxy pollinia each with a somewhat elastic caudicle, deeply bilobed petals and strongly crisped-margined leaves with an apical awn to 1 mm long. These features are an indication of its distant relation to the members of the subtribe Liparidinae, and thus a new subtribe, Ypsilor-chidinae Z. J. Liu, S. C. Chen & L. J. Chen, is proposed.  相似文献   

4.
SYNOPSIS. Female retired breeder A/J mice were infected with Plasmodium berghei NK65C deme. Those animals which recovered were allowed to recrudesce and were inoculated again with NK65C. Twenty-one weeks after the original challenge, the mice were divided into 2 equal groups. One group was challenged with NK65C and the other with NK65E. Both demes of P. berghei were mosquito derived from NK65. NK65C appeared to give less protection to mice challenged with NK65E deme than to those challenged with the homologous NK65C deme. One mouse which had recovered from infection with NK65C deme died from the NK65E challenge. No definitive conclusions could be drawn regarding antigenic variation and virulence between demes E and C.  相似文献   

5.
Singchia Z. J. Liu & L. J. Chen, a new orchid genus, is established based on the new species S. malipoensis Z. J. Liu & L. J. Chen found in southeast Yunnan, China. The new genus is related to Pteroceras, from which it differs by having a lip with its basal margins immovably adnate to the lower part of the pendent column foot, a thin-walled spur, and very unequally and deeply split pollinia, each with a distinct caudicle. In addition to a discussion on Ascocentrum pusillum, a species of questionable placement, another new genus, namely Gunnaria S. C. Chen ex Z. J. Liu & L. J. Chen, is set up and a new combination, namely G. pusilla (Aver.) Z. J. Liu & L. J. Chen, is made. The new genus Gunnaria differs from its allyAscocentrum by having a cross-shaped pollinarium, sulcate or split pollinia, each with a distinct caudicle attached to a common linear stipe much longer than either pollinia or viscidium, and strongly incurved side lobes of the lip.  相似文献   

6.
At the beginning of the 1950s most students of animal behavior in Britain saw the instinct concept developed by Konrad Lorenz in the 1930s as the central theoretical construct of the new ethology. In the mid 1950s J.B.S. Haldane made substantial efforts to undermine Lorenz's status as the founder of the new discipline, challenging his priority on key ethological concepts. Haldane was also critical of Lorenz's sharp distinction between instinctive and learnt behavior. This was inconsistent with Haldane's account of the evolution of language, and, according to Haldane, inconsistent with elementary genetics. British attitudes to the instinct concept changed dramatically in the wake of Daniel S. Lehraman's 1953 critique of Lorenz, and by the 1960s Lorenz drew a clear distinction between his own views and those of the English-speaking ethologists. The inconsistencies between Lorenz's ideas and the trends in contemporary evolutionary genetics that are reflected in Haldane's critiques may help to explain why the Lorenzian instinct concept was unable to maintain itself in Britian.  相似文献   

7.
This paper seeks to reinterpret the life and work of J. B. S. Haldane by focusing on an illuminating but largely ignored essay he published in1927, “The Last Judgment” – the sequel to his better known work, Daedalus (1924). This astonishing essay expresses a vision of the human future over the next 40,000,000 years, one that revises and updates Wellsian futurism with the long range implications of the “new biology” for human destiny. That vision served as a kind of lifelong credo, one that infused and informed his diverse scientific work, political activities, and popular writing, and that gave unity and coherence to his remarkable career. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

8.
The diversity of eukaryotic microorganisms is far from fully described, as indicated by the vast number of unassigned genotypes retrieved by environmental sequencing or metagenomics. We isolated several strains of unicellular green algae from algal biofilms growing on tree bark in a Southeast Asian tropical rainforest and determined them to be relatives of an unidentified lineage of environmental 18S rDNA sequences, thus uncovering its cellular identity. Light, confocal, and electron microscope observations and sequencing the 18S rRNA gene revealed that the strains represent two different species within an apparently new genus, described here as Jenufa gen. nov. Both species formed minute coccoid cells with an irregular globular outline, a smooth cell wall, and a single parietal chloroplast without a pyrenoid. The two species, described herein as J. perforata and J. minuta, differed in chloroplast morphology and cell wall structure. Phylogenetic analyses of 18S rRNA gene sequences showed a firm relationship between the two species and placed the Jenufa lineage in an unresolved position within the CS clade (Chlamydomonadales + Sphaeropleales) of the class Chlorophyceae, although possible affinities to the genus Golenkinia were suggested both by maximum‐likelihood (ML) and Bayesian methods. Furthermore, two almost identical environmental 18S rDNA sequences from an endolithic microbial community occurring in dolomite rock in the central Alps turned out to be specifically related to, yet apparently distinct from, the sequence of J. minuta, indicating the existence of an undescribed Jenufa species occurring in the temperate zone.  相似文献   

9.
The aim of this study was to examine the diversity of, and differentiation between, 41 natural populations representing Juniperus phoenicea complex within their geographic range using the morphological characteristics of cones, seeds, and sprouts with leaves. Seven populations of J. phoenicea s.s., 25 J. turbinata and nine J. canariensis, each represented by ~20–30 individuals, were studied. The characteristics describing the size of cones and seeds and their proportions were different between J. phoenicea s.s., J. turbinata, and J. canariensis, and were useful in distinguishing between these three taxa. The populations of J. canariensis had a significantly higher percentage of trimerous cones, a higher number of cone scales, but a lower number of seeds, which were also larger than the seeds from other taxa. Juniperus phoenicea s.s., J. turbinata, and J. canariensis revealed a high level of multivariate differentiation, but there were no single characteristics which allowed one to distinguish between these alone. We detected significant differences between populations of J. turbinata from Europe and Africa, which supports the role of the Gibraltar Straight in the structuring of conifer species. Significant differences were also detected between European and Asiatic populations in several characters examined, indicating the important role of the Aegean Sea in the structuring of this taxon.  相似文献   

10.
Summary

The differences between Anisopodus White, 1853 and Hyperplatys Haldeman, 1847 are discussed and the gender of the latter is corrected. Notes on Hyperplatys pusillus (Bates, 1863) are provided. Hyperplatys nigrisparsus is considered a new rank for H. pusillus nigrisparsus (Bates, 1885). This species is newly recorded from Brazil (Amazonas). Alcidion laetulum Bates, 1880 (currently Nealcidion laetulum), Alcidion costatum Monné & Martins, 1976 (currently Nealcidion costatum), and Nealcidion murinum Monné, 1998, are synonymized with Alcidion bispinum Bates, 1863 (currently Nealcidion bispinum). Anisopodus melzeri Gilmour, 1965 is transferred to Hyperplatys with a new record from the Brazilian state of Mato Grosso do Sul. Notes on a second specimen of Confluentia colombiana (Gilmour, 1950) are provided. Three new species are described from Ecuador: Nealcidion kayi n. sp. (Acanthocinini), Hyperplatys pichinchensis n. sp. (Acanthocinini) and Confluentia quijos n. sp. (Colobotheini).  相似文献   

11.
记载了中国虎耳草属Saxifraga二新种, 即班玛虎耳草S. banmaensis J. T. Pan和丁青虎耳草S. dingqingensis J. T. Pan。其中, 班玛虎耳草仅见于青海班玛, 与小伞虎耳草S. umbellulata Hook. f. &; Thoms.近缘, 但其萼片先端具软骨质短尖头, 花瓣线形, 非提琴状长圆形至提琴形, 基部无爪, 可资区别。丁青虎耳草见于西藏丁青, 与近加拉虎耳草S. llonakhensis W. W. Smith相似, 但其萼片3脉, 于先端汇合成1疣点, 花瓣具8痂体和4-5脉, 基部截形或近耳形, 可以区别。此两种均系中国特有种, 隶属于莲座状亚组subsect. Rosulares Gornall。  相似文献   

12.
The aim of the work was to specifically differentiate S. typhimurium from other closely related Salmonella serovars by monoplex or multiplex PCR and to detect it from water and food samples. Genes targeted were invA, iroB, STM4497, STM2755, fliC, fljB and rfbJ and evaluated on 58 Salmonella standard serovars/strains including 9 S. typhimurium strains, 7 suspected Salmonella isolates and 8 other organisms as negative controls. Both invA and iroB showed a uniform amplification with all serovars of S. enterica group. STM2755 and STM4497 gene based PCR’s specifically exhibited amplification in all the nine confirmed S. typhimurium strains. The rfbJ PCR produced amplification with confirmed S. typhimurium strains, in addition showed reaction with S. abony. Both STM4497, STM2755 PCR’s and rfbJ could identify two of the seven biochemically suspected Salmonella isolates that were later confirmed to be S. typhimurium on the basis of sequence data. PCR for fliC genes had amplification exhibited by a large number of serovars of the S. enterica group, including S. typhimurium strains but not to S. brunei, S. newporti, S. abony and S. weltevreden. fljB was detected in all strains of S. enterica and E. coli with the exception of S. typhi. fljB and fliC were amplified in 6/7 and 5/7 presumptive Salmonella isolates. The same PCR’s were converted into two multiplex formats for simultaneous identification of the Salmonella genus, S. enterica group and S. typhimurium as a species. The first multiplex set comprised on invA, iroB, STM4497, STM2755 and the IAC. The second multiplex set comprised of invA, iroB, fljB, fliC, rfbJ along with IAC. The detection limit for S. typhimurium in the two multiplex PCR sets was in the range of 350–400 cfu/PCR reaction and that of DNA around 2 pg. The multiplex PCR (format 1) was first evaluated on spiked water, chicken and mutton samples and the detection limit for S. typhimurium was in the range of 100 cfu/100 ml, <60 and <50 cfu/gm, respectively. Further evaluation of multiplex PCR (format 1) was undertaken on 50 natural samples of chicken, eggs, litter, soil etc. and the comparison done with conventional culture isolation and identification procedure. The multiplex PCR could identify the presence of Salmonellla in three samples and the same three samples also yielded Salmonella by the conventional method. Therefore, the presently described multiplex PCR can serve as an alternative to the tedious time-consuming procedure of Salmonella culture and identification in food safety laboratories.  相似文献   

13.
Phyllosiphon arisari Kühn (Phyllosiphonaceae, Chlorophyta) commonly occurs in Arisarum leaves in coastal Mediterranean areas of the Iberian Peninsula and Balearic islands. The genus Phyllosiphon was first considered to be a member of the Xanthophyceae but was later transferred to the chlorophytes. However, there are few data about its morphology, ultrastructure, ecology or phylogenetic affinities. In this paper we describe the morphology of Phyllosiphon, as studied in field material and in culture; the fine structure, analysed by transmission electron microscopy; and phylogenetic relationships, inferred from DNA sequences. The siphonous filaments were seen to divide and penetrate leaf tissues. The cytoplasm divided into spherical or subspherical sporocysts producing autospores inside. Cytoplasmic remains could be observed between autospores or on their cell walls. Phylogenetic analysis of 18S rDNA and 16S rDNA sequences showed that the closest relatives of Phyllosiphon are subaerial strains of Heterochlorella, Heveochlorella and Kalinella, demonstrating that Phyllosiphon should be transferred to Trebouxiophyceae. An evolution from unicells to a siphonous thallus, and from aerophytic to endophytic and parasitic habits, is proposed for Trebouxiophyceae.  相似文献   

14.
The t-lethal haplotypes (t) found in house mouse (Mus musculus) populations are recessive lethals favored by gametic selection whereby male heterozygotes exhibit a non-Mendelian transmission ratio of about 95% t. The expected equilibrium frequency is 0.385; however, empirical values are lower, averaging close to 0.13. We examined the hypothesis that interdemic selection is the cause of the low empirical values by using a deme-structured simulation model that included overlapping generations, a realistic breeding system, differential deme productivity, and a large total population. We found that under some conditions interdemic selection could lower t frequency below 0.13 in the face of immigration rates up to 5%. Low frequencies were correlated with effective deme size (ne), regardless of whether ne was changed through changing deme size (n) or through changing the proportion of breeding adults. Earlier workers showed how the first two phases of interdemic selection (random genetic differentiation and mass selection) interacted to reduce the haplotype frequency, but here we show the importance of the third phase (differential productivity of demes) once demes are linked by dispersal. The effect of this phase is not due to the (negative) covariation between deme productivity and haplotype frequency, but occurs when differential deme productivity generates a difference in t frequency between the population of juveniles recruited into their natal deme and the population of juvenile dispersers. This difference was maximized when the average productivity of demes was low, either because few adult females bred at any one time and/or because fecundity was low. Contrary to an earlier prediction, male-biased dispersal also reduced haplotype frequency, and this probably stems from the relative excess of wild-type genotypes among dispersers compared to the deme residents. Another unexpected finding was that the randomly generated excess of heterozygotes (FIS < 0) found in small demes favored t haplotypes; however, the effect was only seen when the more powerful influence of the third phase of interdemic selection was removed. Simulations of neutral polymorphisms showed that a deme structure giving FST ≤ 0.6 is inconsistent with a haplotype frequency below 0.13. Based on current empirical estimates of FST (about 0.2), we concluded that immigration rates in the field are too high for interdemic selection alone to cause the observed deficit of lethal haplotypes. One factor that could combine with population structure effects is the observation that the transmission ratio is lowered to around 0.6 in litters produced from postpartum estrus (PPE). Incorporating this factor, we showed that interdemic selection could be effective in lowering the frequency of t below 0.13 when FST was above 0.43 even when migration rates were up to 10%. These results suggest that if empirical haplotype and FST estimates are accurate, then additional factors such as a lowered fitness of heterozygotes may be involved.  相似文献   

15.
The land snail genus Schileykula Gittenberger, 1983 is distributed in arid limestone areas from western Turkey to north-western Iran. It comprises eight species, which display high variation in shell size and morphology. The cylindrical shells are 5–12 mm in height and the last shell whorls bear several inner lamellae and plicae. Two taxa differ in their chirality having sinistral shells, while all the others are dextrals such as the vast majority of orculids. The aim of this study was to establish a molecular genetic phylogeny of Schileykula and to test whether it conforms to the current morphology-based classification. Furthermore, we were interested in the phylogenetic position of the two sinistral forms in order to assess whether one or two reversals happened in the evolution of the genus. Nine out of ten species, including all four subspecies of Schileykula trapezensis and three of six subspecies of Schileykula scyphus, were investigated. A section of the mitochondrial cytochrome c oxidase subunit I gene was analyzed in 54 specimens of Schileykula and from a subsample, partial sequences of the mitochondrial genes for the 12S rRNA and the 16S rRNA, and a section of the nuclear H4/H3 histone gene cluster were obtained. The phylogenetic trees based on the mitochondrial sequences feature high support values for most nodes, and the species appear well differentiated from each other. The two chiral forms evolved independently and are not sister lineages. However, some groupings disagree with the present morphology-based classification and taxonomical conclusions are drawn. Schileykula trapezensis is polyphyletic in the molecular genetic trees; therefore, three of its subspecies are elevated to species level: Schileykula acampsis Hausdorf, 1996 comb. nov., Schileykula neuberti Hausdorf, 1996 comb. nov., and Schileykula contraria Neubert, 1993 comb. nov. Furthermore, Schileykula sigma is grouped within S. scyphus in the mitochondrial and nuclear trees and consequently treated as a subspecies of the latter (Schileykula scyphus sigma Hausdorf, 1996 comb. nov.). Schileykula nordsiecki, whose shell morphology is indistinguishable from that of the neighboring Schileykula scyphus lycaonica, but who differs in its genital anatomy, was confirmed to represent a distinct lineage. The phylogenies produced by the mitochondrial and nuclear data sets are to some extent conflicting. The patterns differ concerning the grouping of some specimens, suggesting at least two independent hybridization events involving S. contraria, S. scyphus and S. trapezensis. The results exemplify the importance of integrating both mitochondrial and nuclear sequence data in order to complement morphology-based taxonomy, and they provide further evidence for hybridization across distantly related lineages in land snails.  相似文献   

16.
Although morphological characters distinguishing echiniscid genera and species are well understood, the phylogenetic relationships of these taxa are not well established. We thus investigated the phylogeny of Echiniscidae, assessed the monophyly of Echiniscus, and explored the value of cuticular ornamentation as a phylogenetic character within Echiniscus. To do this, DNA was extracted from single individuals for multiple Echiniscus species, and 18S and 28S rRNA gene fragments were sequenced. Each specimen was photographed, and published in an open database prior to DNA extraction, to make morphological evidence available for future inquiries. An updated phylogeny of the class Heterotardigrada is provided, and conflict between the obtained molecular trees and the distribution of dorsal plates among echiniscid genera is highlighted. The monophyly of Echiniscus was corroborated by the data, with the recent genus Diploechiniscus inferred as its sister group, and Testechiniscus as the sister group of this assemblage. Three groups that closely correspond to specific types of cuticular design in Echiniscus have been found with a parsimony network constructed with 18S rRNA data. © 2013 The Linnean Society of London  相似文献   

17.
The present study describes two new Nostoc species, N. montejanii and N. tlalocii, based on a polyphasic approach that combines morphological, ecological, and genetic characteristics. The five investigated populations, including those from newly collected material from central Mexico, were observed to possess morphological features characteristic of the Nostoc genus. Results showed that both new species are strictly associated with running water, and they show clear differences in their habitat preferences. The 16S rRNA gene sequences of the five strains displayed between 98% and 99% similarity to the genus Nostoc sensu stricto. The 16S rRNA gene phylogenetic analyses inferred using Bayesian inference, maximum likelihood, and parsimony methods, placed these five strains in two separate clades distinct from other Nostoc species. The secondary structures of the 16S–23S internal transcribed spacer rRNA region in the two new species showed >10.5% dissimilarities in the operons when compared with other Nostoc species. In addition, clear morphological differences were observed between the two Mexican species, including the color of the colonies (black in N. montejanii and green in N. tlalocii), the size of the cells (greater in N. montejanii), and the number of polyphosphate granules present in the cells (one in N. montejanii and up to four in N. tlalocii).  相似文献   

18.
The genera of Acanthocinini which have males with antennomere III modified are discussed and redefined, a key to identify them is provided. Additionally, Alcathousites Gilmour, 1962 is proposed as a junior synonym of Xenocona Gilmour, 1960, and the following five new combinations are proposed: Xenocona asperipennis (Fairmaire & Germain, 1859) n. comb.; X. forsteri (Tippmann, 1960) n. comb.; X. penicillata (Monné, 1990) n. comb.; X. senticosa (Monné & Martins, 1976) n. comb.; and X. superstes (Erichson, 1847) n. comb. Moreover, a new species from Colombia (Huila) is described and illustrated, Xenocona antonkozlovi n. sp., and the male of X. penicillata is illustrated for the first time.  相似文献   

19.
Intergeneric hybrids (ABDJJsS genomes) were made between Triticum aestivum cv. Chinese Spring (CS) and Thinopyrum intermedium. Genomic in situ hybridization (GISH) using genomic DNA probes from Pseudoroegneria libanotica (Hackel) D.R. Dewey (genome S, 2n = 14) was used to study chromosome pairing among J, Js, S and wheat ABD genomes in the hybrids. It was shown that in the hexaploid (ABDJJsS) hybrids, high pairing occurred among wheat chromosomes and among Thinopyrum chromosomes. A closer relationship was observed among the three genomes of Th. intermedium than among the three genomes of T. aestivum. It was further discerned that S genome chromosomes paired with J- and Js-genome chromosomes at a high frequency. The frequency of heterologous pairing between S and J or S and Js chromosomes was higher than those between J and Js chromosomes, indicating that the S-genome was more closely related with these two genomes. Our results provided direct molecular cytogenetic evidence for the hypothesis that S-genome chromosomes are genetically similar to the J-genome chromosomes and, therefore, genetic exchange between these genomes is possible. The discovery of a close relationship among S, J and Js genomes provides valuable markers for molecular cytogenetic analyses using S-genomic DNA probes in monitoring the transfer of useful traits from Thinopyrum species into wheat. Received: 23 August 2000 / Accepted: 5 September 2000  相似文献   

20.
祝正银  祝世杰 《植物研究》2011,31(4):385-388
描述了四川峨眉山(茜草科)鸡矢藤属二新种,即峨眉鸡矢藤与长冠鸡矢藤。  相似文献   

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