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 15 毫秒
1.
Summary A strain ofHaplosporangium parvum has been isolated from Italian soil. It has been comparatively studied with six North American and a Korean strain. Two American and the Italian strains are thermophilic (opt. about 35° C) while the other four grow better at temperatures around 20° C.The assimilation of nitrogen sources has been comparatively studied. In addition to peptoneH. parvum metabolizes urea and most aminoacids, whileH. bisporale assimilates peptone, leucine, alanine, glutamic acid and proline only. On the basis of N assimilation and thermophily, a key of the studied strain is established.A comparison ofH. bisporale withH. parvum, confirmed that the former species is a Phycomycete, while the latter is a Moniliaceous, aleuriosporic fungus. All the strains are feebly pathogenic, but the virulence of the Italian soil isolate is equal to that of the most virulent strains isolated from animal lungs (Alberta, Canada).The taxonomy ofH. parvum has been studied in relation to the more or less allied generaAleurisma, Glenosporella, Geomyces andStaphylotrichum.It is concluded thatH. parvum may be better classified as a new genus, and the monotypic genusEmmonsia withE. parva (Emm. etAshb.) n. comb. is proposed, although the entire group of aleuriosporaceous fungi needs revision.  相似文献   

2.
The bradoriid genusHipponicharion Matthew, 1886 is one of the oldest known Cambrian ostracods. Until now, five species have been documented and another three taxa have been tentatively assigned to one or another species.Hipponicharion has been recorded from Poland, Germany, Morocco as well as from Canada and Great Britain.Hipponicharion hispanicum n. sp. represents the first Cambrian ostracod documented from Spain.Hipponicharion taidaltensis n. sp., formerlyH. aff.geyeri Hinz-Schallreuter, 1993 andH. elickii n. sp., formerlyH. cf.eos sensuElicki, 1994 have also been restudied in this paper.Hipponicharion seems to be restricted to the Acadobaltic Province sensuSdzuy (1972). The systematic relationships of the Bradoriida, which is controverse, is briefly outlined, emphasizing close affinities to the Ostracoda.   相似文献   

3.
The maritime shrew, Sorex maritimensis, is a Canadian endemic species with a limited distribution in two provinces in eastern Canada. Phylogeographic analysis of mitochondrial DNA control region and cytochrome b sequences revealed two clades, one found in New Brunswick and the other primarily in Nova Scotia, Canada. We propose that these clades have come back into secondary contact following the Wisconsin glaciation via wetlands on the narrow Isthmus of Chigneto that connects these provinces. Despite evidence of an historic separation of maritime shrew subpopulations in Nova Scotia and New Brunswick, we conclude that shrews in these two regions should be considered a single evolutionary significant unit but separate, semi-isolated management units that should be recognized as such for conservation purposes. The susceptibility of this stenotopic species with limited dispersal capabilities raises concerns about its long-term persistence if climate-change induced habitat fragmentation increases. Maintenance of contiguous wetland habitats is needed to ensure connectivity and gene flow among populations of the maritime shrew.  相似文献   

4.
Despite the important role of shrews (Soricomorpha: Soricidae) in the functioning of ecosystems, as predators and prey, the effects of habitat loss and fragmentation on this guild of mammals are still unclear. We studied the distribution of 5 species (the greater white toothed shrew Crocidura leucodon; the lesser white toothed shrew Crocidura suaveolens; the pigmy shrew Sorex minutus; the Appennine shrew Sorex samniticus and the Etruscan shrew Suncus etruscus) in a fragmented landscape in central Italy.Shrews were trapped with pitfall traps made from plastic water bottles, the number of traps increased with patch size. A total of 170 individuals, of 5 species of shrews were captured. Shrews were widely distributed in our study area, however patch occupancy was determined mainly by vegetation and geometrical characteristics of the patches. Our data supports the hypotheses that patterns of habitat selection and the dynamics of seasonal abundance (habitat and temporal partitioning between similarly sized species) reduce competitive pressure, thus allowing coexistence of shrews in relatively species-rich assemblages, for such small amounts of habitat. The most important outcome of our results is the crucial role played by vegetation structure in determining distribution patterns. These results strongly suggest that measurements of the vegetation structure of habitat patches should always be included as explanatory variables when studying the distribution of shrews in fragmented landscapes.  相似文献   

5.
Summary Microsporum nanum Fuentes was isolated from a ringworm lesion on the back of the hand of a seven year old Alberta schoolgirl. This is the first record ofM. nanum in Canada and the first infection reported from the northern part of the temperate zone.  相似文献   

6.
Silene thebana Orph. exBoiss. is transferred as a subspecies toS. fabaria (L.)Sm., resulting in the new combinationS. fabaria (L.)Sm. subsp.thebana (Orph. exBoiss.)Melzh. The chromosome count of 2n = 24 is recorded for the first time for this taxon.Dedicated to Prof. DrK. H. Rechinger on the occasion of his 80th birthday, 16th October 1986.  相似文献   

7.
The Moscow and Seliger chromosomal races of the common shrew differ by Robertsonian fusions and possibly whole‐arm reciprocal translocations (WARTs) such that their F1 hybrids produce a chain‐of‐eleven configuration at meiosis I and are expected to suffer substantial infertility. Of numerous hybrid zones that have been described in the common shrew, those between the Moscow and Seliger races involve the greatest chromosomal difference. We collected 211 individuals from this zone to generate a total dataset of 298 individuals from 187 unique global positioning system (GPS) locations within the vicinity of interracial contact. We used a geographic information system (GIS) to map the location of the hybrid zone, which follows a direct route between two lakes, as would be anticipated from tension zone theory. Even within the central area of the hybrid zone, there is a much higher frequency of pure race individuals than hybrid, making this a clear example of a bimodal zone in the sense of Jiggins & Mallet (2000) . The zone runs through good habitat for common shrews, but nevertheless it is very narrow (standard cline widths: 3–4 km), as would be anticipated from low hybrid fitness. There is clear potential for an interruption to gene flow and build‐up of reproductive isolation. As found in some other hybrid zones, there is a high frequency of novel genetic variants, in this case, new chromosomal rearrangements. Here, we report a de novo Robertsonian fission and a de novo reciprocal translocation, both for the first time in the common shrew. There is an extraordinarily high frequency of de novo mutations recorded in F1 hybrids in the zone and we discuss how chromosomal instability may be associated with such hybrids. The occurrence of a de novo Robertsonian fission is of considerable significance because it provides missing evidence that fissions are the basis of the novel acrocentric forms found and apparently selected for in certain common shrew hybrid zones.  相似文献   

8.
D. P. Peschken 《BioControl》1977,22(4):425-428
Altica carduorum Guérin-Méneville, a biological control agent against creeping thistle (Cirsium arvense (L.)Scop.) was released in Canada on 2 climatically contrasting release sites. Predation at the southern site, aggravated by slow egg and larval development, and low temperatures at the northern site prevented establishment. Reports from other releases in Canada, Britain and South Dakota are discussed.
Résumé Altica carduorum Guérin-Melville, ennemi naturel du chardon des champsCirsium arvense (L.)Scop. a été laché au Canada dans 2 régions de climat différent. Il n'y a pas eu d'acclimatation à cause de la prédation dans la localité méridionale; dans le site septentrional ce phénomène a été aggravé par un développement embryonnaire et larvaire lent et par de basses températures. Les données sur d'autres lachers faits au Canada, en Grande-Bretagne et dans le Dakota du Sud sont discutées.
  相似文献   

9.
  • 1 Skeletal remains of greater white‐toothed shrew Crocidura russula were recovered from barn owl Tyto alba and kestrel Falco tinnunculus pellets collected at 15 locations in Counties Tipperary and Limerick in Ireland in September 2007 and March 2008. Seven greater white‐toothed shrews were trapped at four locations in Tipperary in March 2008. This is the first Irish record of C. russula and compelling evidence that the species is established in Ireland.
  • 2 The absence of C. russula from earlier surveys of owl pellets and small mammals in Ireland suggests a recent introduction by uncertain means, possibly since 2001. It seems likely that C. russula will expand its range in Ireland. Its impact on the ecology of habitats in which it is found is uncertain but may be considerable.
  相似文献   

10.
Two sequences of about 10.5 m originating from a peat bog in Romania were analysed for pollen (202 and 127 pollen spectra). The vegetation history, supported by 24 14C dates is described since the Late Glacial. At the onset of the Holocene Ulmus first appears, together with Betula. Among the main components of the Quercetum mixtum (Quercus, Fraxinus, Tilia, Corylus) that became established almost simultaneously by around 9000 B.P., Quercus frequencies rarely exceed 10%. The local establishment of Carpinus is about 6000 b.p. Its maximum occurred between 4500 and 3000 b.p. Fagus pollen is regularly recorded since 8000 b.p. Its absolute dominance tooks place at about 3000 b.p. Picea pollen is present since the Late Glacial. The first indications of human activities appear at around 6500 b.p.  相似文献   

11.
Summary The pathogenFusarium solani sensuSnyder &Hansen, as identified byW. L. Gordon was recorded in the present work as a new species causing cotton wilt in Egypt. Cotton dust in varying concentrations does not significally alter the normal infection of both Menoufi and Giza 26 cotton varieties towardsFusarium. Similarly the potency ofFusarium filtrate to induce wilting did not appreciably change with previous treatment of cotton plants with cotton dust. On the other hand leaves treated with 2,4-D showed the maximal water loss. Percentage infected Giza 26 cotton seedlings were found to be comparatively less in soil infected with 2,4-D treatedFusarium mycelium than in that infected with untreated mycelium.  相似文献   

12.
M. Khan 《Hydrobiologia》1973,43(1-2):171-175
The present communication deals with the morphological features of a fresh water red alga Lemanea mamillosa Kutz. It has been recorded for the first time from India. Its economic value as food material is mentioned.  相似文献   

13.
Capsule White-throated Dippers from southern Europe were found to be infected by three haemosporidians.

Aims To examine the occurrence of blood parasites in dippers in the Iberian Peninsula and to investigate the relationship between prevalence levels, environmental factors and bird fitness.

Methods White-throated Dippers were trapped with mist-nets from five montane areas in the centre of the Iberian Peninsula. Parasites were detected from blood samples by polymerase chain reaction screening.

Results About half (51.3%) of 152 dippers showed some kind of infection. The genus Haemoproteus was recorded in 49.3% of the birds, and the genus Leucocytozoon in 19.1%, while Plasmodium was present only in 0.7%. Among the infected birds, 34.6% carried a double infection (Haemoproteus?+?Leucocytozoon). Prevalence did not differ between gender or age-classes, but it varied between study sites, being significantly higher in mountains with higher precipitation. There was a reduction in body mass owing to double infection in yearling males only.

Conclusion This is the first work assessing parasite prevalence in dippers from southern Europe. Infection of dippers by haemosporidians is likely to be related to a study site's climatic envelope.  相似文献   

14.
M. Khan 《Hydrobiologia》1970,35(2):249-253
Summary The present communication deals with morphological features of a new fresh water species of the genus Acrochaetium Naëg. (A. sarmaii sp. nov.). The occurrence of Compsopogon iyengarii is also recorded for the first time from a locality in North India.  相似文献   

15.
Effect of soil fungistasis on zoopathogenic fungi   总被引:1,自引:0,他引:1  
The inhibiting action of west-Siberian soils on spore germination and the growth and development of zoopathogenic fungi such as Emmonsia (Chrysosporium) crescens, Trichophyton mentagrophytes, Beauveria bassiana, Metarrhizium anisopliae, Paecilomyces farinosus, P. fumoso-roseus and Chrysosporium keratinophilum have been studied by the authors. The influence of carbon sources and the root exudates of plants on fungistasis have also been studied.  相似文献   

16.
Lyme disease is reported across Canada, but pinpointing the source of infection has been problematic. In this three‐year, bird‐tick‐pathogen study (2004–2006), 366 ticks representing 12 species were collected from 151 songbirds (31 passerine species/subspecies) at 16 locations Canada‐wide. Of the 167 ticks/pools tested, 19 (11.4%) were infected with Borrelia burgdorferi sensu lato (s.l.). Sequencing of the rrf‐rrl intergenic spacer gene revealed four Borrelia genotypes: B. burgdorferi sensu stricto (s.s.) and three novel genotypes (BC genotype 1, BC genotype 2, BC genotype 3). All four genotypes were detected in spirochete‐infected Ixodes auritulus (females, nymphs, larvae) suggesting this tick species is a vector for B. burgdorferi s.l. We provide first‐time records for: ticks in the Yukon (north of 60° latitude), northernmost collection of Amblyomma americanum in North America, and Amblyomma imitator in Canada. First reports of bird‐derived ticks infected with B. burgdorferi s.l. include: live culture of spirochetes from Ixodes pacificus (nymph) plus detection in I. auritulus nymphs, Ixodes scapularis in New Brunswick, and an I. scapularis larva in Canada. We provide the first account of B. burgdorferi s. l. in an Ixodes muris tick collected from a songbird anywhere. Congruent with previous data for the American Robin, we suggest that the Common Yellowthroat, Golden‐crowned Sparrow, Song Sparrow, and Swainson's Thrush are reservoir‐competent hosts. Song Sparrows, the predominant hosts, were parasitized by I. auritulus harboring all four Borrelia genotypes. Our results show that songbirds import B. burgdorferi s.l.‐infected ticks into Canada. Bird‐feeding I. scapularis subadults were infected with Lyme spirochetes during both spring and fall migration in eastern Canada. Because songbirds disperse millions of infected ticks across Canada, people and domestic animals contract Lyme disease outside of the known and expected range.  相似文献   

17.
Zusammenfassung In einer 2-Weg-Wahlapparatur wurden mittels Futterdressur bei mehreren Spitzhörnchen verschiedene Leistungen des Auges geprüft. Außerdem wurde der dioptrische Apparat des Tupaiauges untersucht.
Experiments on the physiology of the eye of the tree shrew Tupaia glis (Diard, 1820)
Summary Different abilities of the eyes of several tree shrews were tested in two-way reinforcement experiments. In addition the dioptric system of the eye was examined.
  相似文献   

18.
To forecast the potential impact of plant community and dry-stone wall restoration on an insular population of the lesser white-toothed shrewCrocidura suaveolens Pallas, 1811, shrew and house mouseMus musculus Linnaeus, 1758 abundances were assessed in 3 anthropogenic habitats on Béniguet Island, Brittany, France, by a standardised annual trapping system checked yearly for 9 years and in 6 “natural” habitats by trap-lines. The standardised trapping system showed that abundances of both species fluctuated synchronously for nine years, suggesting that interactions between the species had little impact if any on abundances. Mice were trapped in all habitats, but shrews only in “stone” habitats except for rare occurrences in one damp depression. Ruderal habitat was rarely used by either species. Data suggest that on Béniguet Island: (1)M. musculus is associated with anthropogenic habitats but is not as strictly tied to them as at nearby continental sites; (2)C. suaveolens is synanthropic, as has been reported in continental northern France; (3) shingle beaches and seashore food resources are particularly important forC. suaveolens; (4) the relationship betweenC. suaveolens andM. musculus could not be determined by the experiments and, if it exists at all, appears to be more competitive than predatory. Grassland restoration is unlikely to affect shrew populations. Dry-stone wall restoration may temporarily affect shrews but should ultimately benefit them.  相似文献   

19.
Callovian strata in northern Lithuania (Papilė area) have yielded some crinoid taxa[Chariocrinus andreae (Desor),Balanocrinus berchteni HessPugin,B. subteres (Münster inGoldfuss) andIsocrinus nicoleti (Desor)], which have not been described from this area. The only form known previously wasBalanocrinus pentagonalis (Goldfuss).Palaeocomaster jaegeri n. sp. is the first free-living crinoid recorded from the Callovian of eastern Europe. It is characterized by possessing a very low, strongly flattened and narrow radial cavity. A very similar crinoid assemblage is known from the Callovian glacially-derived clays exposed in the Łuków region (eastern Poland), which were originally located near the Baltic Sea during the Middle Jurassic. It is considered that the allochthonous Callovian deposits from Poland are facies equivalents of the deposits known from Lithuania. The sole significant exception is the domination of free-moving comatulids (Comatulida) in the sediments known from the Papilė region, which may suggest that the Lithuanian sea basin was a little shallower than that located farther west in the Baltic area.   相似文献   

20.
Summary The biosynthesis of phytic acid is known to be catalyzed by enzymes causing a stepwise phosphorylation of myo-inositol or 1l-myo-inositol 1-phosphate with adenosine triphosphate as phosphate donor. The kinases responsible for these phosphorylations in Lemna gibba were purified by affinity chromatography on a Sepharose gel carrying myo-inositol 2-phosphate at the binding site. Three fractions with enzymatic activity could be identified; in the first one, we find myo-inositol kinase (EC 2.7.1.64) phosphorylating myo-inositol to 1l-myo-inositol 1-phosphate; the second one brings about the phosphorylation of myo-inositol trisphosphate to phytic acid; the third one phosphorylates myo-inositol 1-phosphate to a myo-inositol trisphosphate. An enzyme oxidizing 1l-myo-inositol 1-phosphate to an uronic acid derivative is found in the first two fractions. In the presence of ATP, Mg2+ Mn2+, and the second and the third enzyme fractions in an appropriate mixture, 1l-myo-inositol 1-phosphate can be phosphorylated to phytic acid. The structure of the trisphosphate acting as an intermediate is not yet known.  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