共查询到20条相似文献,搜索用时 15 毫秒
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Stoecker Diane K.; Gallager Scott M.; Langdon Chris J.; Davis Linda H. 《Journal of plankton research》1995,17(5):1105-1124
Particle capture by the tintinnid ciliate, Favella sp., wasinvestigated with high-speed video microscopy. Experiments withmicrospheres and algal cells indicate that within the size range119 p.m. behavioral responses are partly responsiblefor the differential capture of large over small particles.For example, 4 µm microspheres or Isochrysis [spheiicaldiameter (ESD) - 4.5 µ are only captured if they are encounteredin the inner zones of the encounter area. Ten micrometer microspheresor Heterocapsa(1419 are captured with a greaterefficiency than smaller particles from the inner zones, butcan also be captured from the outer zone of the encounter area.Capture of particles from the outer zone is associated withcilialy reversal. Microsp1ieres and algal cells of similar sizeare captured in a similar manner. 相似文献
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T. Karanovic 《Helgoland Marine Research》2000,54(1):33-38
A new species of Arenopontia (Neoleptastacus) is described on the basis of a single female collected from one sandy beach in Montenegro, Adriatic Sea. With the addition
of the new species, the subgenus Neoleptastacus now includes 18 species throughout the world. At the end of this paper there is a key for their determination.
Received: 20 March 1999 / Received in revised form: 15 September 1999 / Accepted: 21 September 1999 相似文献
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Vinícius P. Maccarini Lindamir H. Pastorini Gledson V. Bianconi Henrique Ortêncio-Filho 《Studies on Neotropical Fauna and Environment》2018,53(1):1-9
Bats are responsible for many ecological services, such as seed dispersal of several plant species, contributing to the processes of succession and forest regeneration. A factor that can interfere with this process is the animal digestion, which can affect germination, altering the patterns of seedling distribution. The effects of seed passage through bats’ guts varies with the species, leading to some discrepancies in the literature. In this study, we tested the digestion time of one Phyllostomidae bat species, Sturnira lilium, in two Neotropical plants: Solanum paniculatum and Ficus organensis, and the effects on seed germination. The experiment was conducted in captivity and the germination tests were made in laboratory conditions. The results suggested that most seeds ingested by S. lilium are dispersed within 40 min for both species and the digestion seems not to significantly affect the germination of F. organensis, despite the slight acceleration of germination. In S. paniculatum, germination occurred only in the control (39%), whereas in the treatments, all the seeds remained dormant during the 25 experimental days. In this case, the digestion of S. lilium possibly contributes to the formation of seed banks, randomizing the temporal distribution of seedlings. 相似文献
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Elliott GN Chen WM Bontemps C Chou JH Young JP Sprent JI James EK 《Annals of botany》2007,100(7):1403-1411
BACKGROUND AND AIMS: Species of the genus Burkholderia, from the Betaproteobacteria, have been isolated from legume nodules, but so far they have only been shown to form symbioses with species of Mimosa, sub-family Mimosoideae. This work investigates whether Burkholderia tuberum strains STM678 (isolated from Aspalathus carnosa) and DUS833 (from Aspalathus callosa) can nodulate species of the South African endemic papilionoid genera Cyclopia (tribe Podalyrieae) and Aspalathus (Crotalarieae) as well as the promiscuous legume Macroptilium atropurpureum (Phaseoleae). METHODS: Bacterial strains and the phylogeny of their symbiosis-related (nod) genes were examined via 16S rRNA gene sequencing. Seedlings were grown in liquid culture and inoculated with one of the two strains of B. tuberum or with Sinorhizobium strain NGR 234 (from Lablab purpureus), Mesorhizobium strain DUS835 (from Aspalathus linearis) or Methylobacterium nodulans (from Crotalaria podocarpa). Some nodules, inoculated with green fluorescence protein (GFP)-tagged strains, were examined by light and electron microscopy coupled with immunogold labelling with a Burkholderia-specific antibody. The presence of active nitrogenase was checked by immunolabelling of nitrogenase and by the acetylene reduction assay. B. tuberum STM678 was also tested on a wide range of legumes from all three sub-families. KEY RESULTS: Nodules were not formed on any of the Aspalathus spp. Only B. tuberum nodulated Cyclopia falcata, C. galioides, C. genistoides, C. intermedia and C. pubescens. It also effectively nodulated M. atropurpureum but no other species tested. GFP-expressing inoculant strains were located inside infected cells of C. genistoides, and bacteroids in both Cyclopia spp. and M. atropurpureum were immunogold-labelled with antibodies against Burkholderia and nitrogenase. Nitrogenase activity was also shown using the acetylene reduction assay. This is the first demonstration that a beta-rhizobial strain can effectively nodulate papilioinoid legumes. CONCLUSIONS: Papilionoid legumes from widely different tribes can be nodulated by beta-rhizobia, forming both indeterminate (Cyclopia) and determinate (Macroptilium) nodules. 相似文献
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Arctodiaptomus (Rhabdodiaptomus) michaeli n.sp. is described from the material collected in Alapathar Lake and Marsar Lake of Kashmir, India. 相似文献
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Fernanda Ramlov Tiago José Griebeler Carvalho Éder Carlos Schmidt Cintia Dalcuche Leal Martins Marianne Gabi Kreusch Eva Regina de Oliveira Rodrigues Cláudia Marlene Bauer Zenilda Laurita Bouzon Paulo Antunes Horta Marcelo Maraschin 《Journal of applied phycology》2014,26(4):1879-1888
Understanding the mechanisms by which marine organisms cope to environmental stressful conditions is a fundamental question for ecotoxicology. We examined biochemical and cellular responses of Hypnea musciformis exposed in vitro to four concentrations of diesel oil (0 (control), 0.001, 0.01, 0.1, and 1 % v/v) for 0, 30 min, 1, 12, and 24 h. Chl a content decreased after exposure for 1, 12, and 24 h. Carotenoids increased after 30 min and 12 h and decreased after 1 and 24 h. Phenolic content was lower in samples exposed to 0.1 and 1 % of diesel oil. After treatment, samples showed a decrease in floridean starch grains, cell volume and autofluorescence intensity, changes in chloroplast morphology, and on the surface topography of the cell wall. These findings provide preliminary but important results on biochemical and cellular responses of H. musciformis when exposed to diesel oil and could be considered as tools for monitoring oil spills. 相似文献
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Paramecium quadecaurelia is a rare species (previously known only from two locations) belonging to the P. aurelia species complex. In the present paper, fragments of an rDNA gene (ITS1-5.8S-ITS2-5′ rDNA) and mtDNA genes (cytochrome oxidase subunit I and cytochrome b regions) were employed to assist in the identification and characterization of three new strains collected from Ecuador and Thailand. Molecular data were confirmed by mating reactions. In rDNA and mtDNA trees constructed for species of the P. aurelia complex, all P. quadecaurelia strains, including the three new strains discussed in this study and two known previously from Australia and Africa, form a monophyletic but differentiated clade. The present study shows that genetic differentiation among the strains of P. quadecaurelia is equal to or even greater than the distances between some other P. aurelia species, e.g., P. primaurelia and P. pentaurelia. Such great intra-specific differentiation may indicate a future splitting of the P. quadecaurelia species into reproductively isolated lines. 相似文献
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A new unicellular species of the genusChrysosphaerella (Chrysophyceae) was found in fresh-water ponds in Switzerland, Japan, and the U.S.A. It is described asC. solitaria. The genus is divided into two subgenera:Chrysosphaerella, comprising the colonial species, andPseudochrysosphaerella, the unicellular ones. 相似文献
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Alfredo Pérez-Morales Christine J. Band-Schmidt José L. Ortíz-Galindo Alma S. Sobrino-Figueroa 《Hydrobiologia》2014,722(1):247-261
Fish are particularly sensitive to metabolites produced by Raphidophyte species and these have caused intensive fish kills in several countries. However, the effects on embryos of marine fish are unknown but could probably provoke an important impact on new stock recruitment and hence on fisheries. We evaluated the toxic effects of Chattonella spp. strains from the Gulf of California on three development stages of spotted sand bass (Paralabrax maculatofasciatus): embryo in segmentation stage (ES), embryo (EM), and eleutheroembryo (EL). Embryos (ES) were exposed to different cell concentrations of Chattonella subsalsa, Chattonella marina, Prorocentrum micans, and f/2 medium as control. Also, one set of embryos was tested with cell-free media for C. subsalsa cultures. Incubation lasted until embryos reached apterolarva phase. The ES was the most sensitive stage reaching 98% mortality with C. subsalsa, followed by cell-free media of C. subsalsa cultures, with mortalities close to 90%, whereas EM and EL phases presented mortalities below 60%. This work demonstrates that larval stages of P. maculatofasciatus are highly sensitive to short time exposure to all Chattonella spp. strains tested, that direct physical contact with cells is not required to cause mortality, and that the toxic effect is more pronounced when embryos hatch. 相似文献