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1.
A glyco-peptido lipid fraction ("AF") from the alcoholic extract of Trichopus zeylanicus Gaertn. was evaluated for putative antistress activity in a battery of tests. "AF" exhibited significant antistress activity in dose dependent manner in all the parameters studied, against the different stresses use to induce non-specific stress. Ashwagandha, the commercial extract of Withania somnifera roots was used as control: A preliminary acute toxicity study in mice showed a good margin of safety, as the ALD50 value was more than 3000 mg/kg body wt. p.o. with no signs of abnormalities.  相似文献   

2.
Summary The red mangrove (Rhizophora mangle L.) occurs frequently in both scrub and fringe mangrove forests. Our previous study demonstrated that individuals of this mangrove species growing in scrub and fringe forests differ significantly in both morphological and physiological characteristics. To further characterize physiological differences between scrub and fringe mangroves, we compared their differences in water uptake and photosynthetic gas exchange during different seasons. In the wet season (June–October, 1990), scrub mangroves showed lower D and 18O values of stem water than fringe mangroves, indicating more usage of rain-derived freshwater. In the dry season (Jan–April, 1991), however, scrub mangroves utilized the same water source as fringe mangroves, reflected by their similar D and 18O values of stem water. Consistently, there were significant differences in predawn water potentials between scrub and fringe mangroves in the wet season (October 1990) with higher values for scrub mangroves, but no significant differences in the dry season (January 1991). Higher elevation in the scrub forest seems to be the major factor responsible for the shift of water sources in scrub mangroves. On Apr. 27 and Aug. 8, 1990, scrub mangroves showed lower CO2 assimilation rate, stomatal conductance, and intercellular CO2 concentration than fringe mangroves. There were no differences in these gas exchange characteristics on the other two measuring dates: Oct. 17, 1990 and Jan. 11, 1991. Instantaneous water use efficiency was significantly higher for scrub mangroves than for fringe mangroves on three of the four sampling dates. Similarly, leaf carbon isotope discrimination of scrub mangroves was always significantly lower than that of fringe mangroves, indicating higher long-term water use efficiency. Higher water use efficiency in scrub mangroves is a result of stomatal limitation on photosynthesis, which may entail considerable carbon cost to the plants.  相似文献   

3.
The cyanogenic polymorphism in Trifolium repens is caused by the variation in two genes, the interaction of which produces four distinct cyanotypes. Along the Atlantic coasts of Bretagne, T. repens is sometimes found in populations mixed with the related species Trifolium occidentale, although the latter species usually occurs only in a narrow fringe along the coast, whereas T. repens is a more inland species. No plants of T. occidentale have ever been reported to have linamarase activity. Indeed, of 763 T. occidentale plants studied, none contained linamarase activity. However, the variation in the proportion of cyanotypes in T. repens was enormous, even between sites less than 2km apart. Our results confirm the presumption that T. repens and T. occidentale are indeed separate species. Both the fact that T. occidentale plants never contain linamarase activity, and the difference in proportion of plants with cyanoglucosides in mixed stands show that gene flow between the species must be rare. These dissimilar distributions strongly indicate that cyanotypic frequencies in adjacent and mixed populations of the very closely related species T. occidentale and T. repens are regulated by different mechanisms  相似文献   

4.
A site in the western part of Long Island Sound was monitored from January 2000 to May 2002. The littoral was divided into five different zones from the supra-littoral fringe (A) to the infra-littoral fringe (E). The midshore was dominated by Fucus vesiculosus L. and the sublittoral fringe by Chondrus crispus Stackh. There was a significant change in community structure over the years and the predominant change occurred between 2001 and 2002. The alternation in community structure was caused by an increase in abundance of species like Porphyra suborbiculata Kjellm., Porphyra leucosticta Type A and C (Neefus et al. 2000), Ceramium virgatum Roth, and Codium fragile subsp. tomentosoides (van Goor)Silva and a decrease in abundance in Fucus vesiculosus, Blidingia minima (Nägeli ex Kütz.) Kylin and Ulva lactuca L. The changes in community structure coincided with the change in environmental conditions. Air temperature as well as surface seawater temperature (depth <2 m) were the most important factors of those analyzed. Temperature seems to be the bottom-up force regulating the community structure.  相似文献   

5.
Hybridization is regarded as a rapid mechanism for increasing genetic variation that can potentially enhance invasiveness. Tamarix hybrids appear to be the dominant genotypes in their invasions. Exotic Tamarix are declared invasive in South Africa and the exotic T. chinensis and T. ramosissima are known to hybridize between themselves, and with the indigenous T. usneoides. However, until now, it was not known which species or hybrid is the most prevalent in the invasion. With a biocontrol programme being considered as a way of suppressing the alien Tamarix populations, it is important to document the population genetic dynamics of all species in the region. This investigation sought to identify Tamarix species in southern Africa and their hybrids, describe their population structure, and reveal the geographic origin of the invasive species. To achieve this, nuclear Internal Transcribed Spacer (ITS) sequence data and the multilocus Amplified Fragment Length Polymorphisms (AFLPs) markers were used. Phylogenetic analysis and population genetic structure confirmed the presence of three species in South Africa (T. chinensis, T. ramosissima and T. usneoides) with their hybrids. The indigenous T. usneoides is clearly genetically distant from the alien species T. chinensis and T. ramosissima. Interestingly, the Tamarix infestation in South Africa is dominated (64.7 %) by hybrids between T. chinensis and T. ramosissima. The exotic species match their counterparts from their places of origin in Eurasia, as well as those forming part of the invasion in the US.  相似文献   

6.
A new species, Anthonomus dilatofemurus Poinar et Legalov, sp. nov., from Mexican amber is described and illustrated. The new species is close to A. cruraluma Poinar et Legalov and differs from it in the wider elytra with narrow striae and strongly swollen pro- and metafemora. It differs from A. browni Poinar et Legalov in the wide and short elytra, shorter and thicker weakly curved rostrum, and strongly swollen metafemur. It is distinguished from A. camoiranensis Clark by the metatitibia with uncus and from A. sulcatus Kirsch by the protibia with uncus, metatibia with ventral fringe of medium scales, narrower elongate pronotum, weakly convex elytra and weakly curved rostrum.  相似文献   

7.
Understanding how the biodiversity response to climate change will be modified at ecological scales, e.g. by species interactions, is a major challenge. Lichen epiphytes – the close interdependent relationship between a heterotrophic fungus and photosynthetic partner (photobiont) – are used here to explore how interaction regimes (between lichen species, and between lichens and their photobionts) explain distribution patterns along spatial climatic gradients. To do this we tested field evidence for the ‘core‐fringe hypothesis’, which proposes a facilitative interaction; sexually‐reproducing and spore‐dispersed lichens with a requirement for resynthesis with a compatible photobiont (Nostoc) are facilitated by the prior establishment of asexual lichens which disperse both the fungus and photobiont together. We used two closely related Nephroma species which differ in their reproductive mode – N. laevigatum (sexual spore‐dispersed) and N. parile (asexual) – and compared their occurrence along a bioclimatic gradient to local habitat factors, including the co‐occurrence of asexual lichens which have shared specificity for compatible Nostoc genotypes. The results showed that: 1) N. laevigatum is significantly more likely to occur on trees that have already been colonised by asexual lichens with shared specificity for Nostoc, supporting the core‐fringe hypothesis, while 2) N. parile is independent of this association (strengthening the core‐fringe hypothesis), with its response to a precipitation gradient modified by microhabitat factors. This positive test for the core‐fringe hypothesis demonstrates how interaction regimes can fundamentally alter expectations under climate change. There is an assumption that spore‐dispersed lichen species could more easily track their suitable bioclimatic space through fragmented habitat, compared to asexual species with larger and heavier propagules. However, the establishment of spore‐dispersed lichen epiphytes into new habitat may be limited by the dispersal rates of asexual species, which act as key facilitators.  相似文献   

8.
To better understand the diversity and species composition of arbuscular mycorrhizal fungi (AMF) in mangrove ecosystems, the AMF colonization and distribution in four semi-mangrove plant communities were investigated. Typical AMF hyphal, vesicle and arbuscular structures were commonly observed in all the root samples, indicating that AMF are important components on the landward fringe of mangrove habitats. AMF spores were extracted from the rhizospheric soils, and an SSU rDNA fragment from each spore morph-type was amplified and sequenced for species identification. AMF species composition and diversity in the roots of each semi-mangrove species were also analyzed based on an SSU-ITS-LSU fragment, which was amplified, cloned and sequenced from root samples. In total, 11 unique AMF sequences were obtained from spores and 172 from roots. Phylogenetic analyses indicated that the sequences from the soil and roots were grouped into 5 and 14 phylotypes, respectively. AMF from six genera including Acaulospora, Claroideoglomus, Diversispora, Funneliformis, Paraglomus, and Rhizophagus were identified, with a further six phylotypes from the Glomeraceae family that could not be identified to the genus level. The AMF genus composition in the investigated semi-mangrove communities was very similar to that in the intertidal zone of this mangrove ecosystem and other investigated mangrove ecosystems, implying possible fungal adaptation to mangrove conditions.  相似文献   

9.
Results of comparative analysis of specific features of morphology of larval lanternfishes of the Indo-Pacific genus Triphoturus based on materials from the southeastern part of the Pacific Ocean, northwestern Pacific, South China Sea, and the western part of the Indian Ocean, as well as on published data, are provided. Noticeable differences are shown in specific features of pigmentation of larval T. nigrescens (sensu Hulley, 1986) from different parts of the vast range of this species, that may be accounted for by its individual and/or geographic variation and by the collective pattern of this taxon. It is stated that it is necessary to use genetic data for the verification of the taxonomic status of the representatives of the genus. Morphological evidence in favor of the species isolation of T. oculeum and T. microchir based on larval materials is presented. The presence of three morphologically different forms of larval Triphoturus from the eastern Pacific differing in the pattern of body pigmentation that are identified with three nominal species of the genus Triphoturus—T. nigrescens, T. mexicanus, and T. oculeum—is confirmed. The study of specific features of distribution of larvae of these species in southeastern waters of the Pacific Ocean based on our own and published materials revealed the presence of larval T. mexicanus and T. oculeum off Peru, which is supported by data on the presence of adult individuals of both species here.  相似文献   

10.
For all stations, we established a sharing in space and time (according to abondance-dominance test) and we tried to represent the relative importance, by quadrats, for Angiosperms. We display the vegetal zonation in the side of the lagoon. The terrestrial species are distributed especially along the winter inundation fringe and the species of salty soils in the summer waterside fringe. In the intermediate zone are located species which can stand more water and more salinity.

Laboratoire de Biologie Végétale, E.N.S., TUNIS  相似文献   

11.
This paper re-examines the species of Triplophyllum in the neotropics. The indument of the laminae (hairs and glands) provides many characteristics for distinguishing the species. Nine species are recognized, including three new ones: T. boliviense, T. chocoense, and T. glabrum. New combinations are made for T. hirsutum and T. perpilosum . A key is provided to distinguish the species, and all species are described and illustrated. The spores of the neotropical species are like those from African and Madagascan species. As such, they offer no evidence to determine whether the neotropical species form a monophyletic clade within the genus.  相似文献   

12.
Adult Tesseropora rosea (Krauss) and Tetraclitella purpurascens (Wood) are mostly found in the eulittoral (barnacle) zone of rocky seashores in New South Wales. Below this zone most space is occupied by the tube-worm Galeolaria caespitosa (Lamarck) or by various species of macroalgae. Within the eulittoral zone, T. rosea are mostly on sunny areas of rock exposed to relatively strong wave-action. T. purpurascens are present mainly in crevices, caves, and under ledges where there is considerable shade.Cyprids of both species settled on sandstone plates and on experimentally cleared areas in the barnacle and Galeolaria zones. Neither species settled where the substratum was already covered by algae or Galeolaria. No spat of T. purpurascens were found in sunny areas of the barnacle zone. T. rosea, however, settled in cleared substrata in sunny and shaded areas. Neither species settled in the littoral fringe above the upper limit of distribution of adults. On boulders transferred to high levels of the shore during a storm, small T. purpurascens died within a few weeks.Barnacles of both species which had settled in experimentally cleared areas in the Galeolaria zone survived and grew. In these areas some T. purpurascens were killed by being smothered by tube-worms which settled after the barnacles. This probably happens to T. rosea, but was not demonstrated experimentally. In the Galeolaria zone, both species of barnacles were very quickly smothered and killed by macroalgae growing over them, except where these were experimentally removed.Within the barnacle zone, all newly-settled spat of T. purpurascens transferred to sunny sites died within two months, whilst many of those in shaded sites survived. In areas where wave-action was strong, spat of T. rosea survived and grew well in sunny areas, but survived better in the shade. Under a ledge, however, where wave-action was reduced, all the T. rosea in sunny sites, and most of those in shaded sites died within two months; many newly-settled T. purpurascens survived in the shade in this area.The grazing limpet Cellana tramoserica (Sowerby) dislodged and crushed some newly-settled T. rosea and reduced survival in some sunny areas. T. rosea settled preferentially on bare rock and were rarely found on the shells of adult barnacles. Thus, the density of spat was greater where adult barnacles were absent. In contrast, many newly-settled T. purpurascens were found on the shells of adults of their own species in shaded areas; they also settled on cleared rock. Because T. purpurascens tended to settle amongst and on adults, and in crevices and confined areas, they were not much affected by limpets. When newly-settled T. purpurascens were in high densities, they had lower survival than in areas with reduced densities, because of squashing and smothering by each other.The upper and lower limits of vertical distribution (zonation) of these two species of barnacles are determined primarily by the settlement of cyprids. Neither species settled at the highest levels on the shore. Whether this was due to the decreasing time of submersion during high tide towards the top of the shore, or a result of preferences for settlement site is unknown. Even if cyprids were to settle in the littoral fringe, the spat would die very quickly probably as a result of desiccation. Below the barnacle zone, the entire substratum is usually occupied by other sessile species, particularly macroalgae, on which the barnacles do not settle. In experimentally cleared areas below the barnacle zone, or in any naturally cleared areas both species settled, and could survive the physical conditions. Newly-settled spat were, however, overgrown and killed by algae and Galeolaria.Within the barnacle zone, T. purpurascens is restricted to shaded areas because of the inability of newly-settled spat to survive the physical stresses of high temperature and desiccation in sunny habitats. T. rosea appears to be excluded from shaded areas by a combination of the lack of suitable substrata on which to settle, and the effects of reduced water-flow in many crevices and under ledges. T. rosea survived better in areas with strong wave-action and can survive in shaded areas where water-flow is not reduced by the topography of the substratum.  相似文献   

13.
A new truffle species, Tuber lannaense, is described based on collections from northern Thailand. This species is characterized by yellow-brown to brown ascomata with dark brown gleba and ellipsoid to narrow ellipsoid spores with spiny reticulum. It grows in mycorrhizal association with Betula alnoides and Carpinus poilanei. Tuber lannaense is similar to T. huidongense, but differs in the thinner outer peridium layer. Molecular phylogenetic analysis of the internal transcribed spacers (ITS1?+?ITS2) and large subunit of nuclear ribosomal DNA, as well as genetic distance analysis of ITS1?+?ITS2, support T. lannaense as being distinct from other Tuber species. Moreover, based on genetic distance analysis, we consider that T. furfuraceum and T. huidongense, which have previously been synonymized, are different species.  相似文献   

14.
Summary The first morphological examination of the surface and internal anatomy of the kinorhynch, Echinoderes dujardini was undertaken using the scanning and transmission electron microscopes.The oral styles and at least the first ring of scalids were found to have a basal pectinate fringe that resembles the pectinate fringe found at the posterior margins of the trunk segments. In addition to the fringe, the scalids were subdivisible into at least two distinct classes which are similar in structure to the trichoscalid and type I spinocalid identified by Moritz and Storch in T. giganteus. The trichoscalid of E. dujardini however, was found to possess a unique fluted cuticle structure with spines arising only on the medial surface.Although pores are known to occur in the cuticle of homalorhagid kinorhynchs, such pores were not found in the cyclorhagid, E. dujardini.A structure, provisionally designated sensory-like structure is described. Some 60 or more compactly placed spines occur as paired circles or ellipses on all but the terminal trunk segment.An electron dense structure was seen in the subsurface of the placids that may lend mechanical support and may contribute to the Napoleon hats seen with light microscopy. Micrographs of the circumentric nerve ring, gut, epidermis and pharynx are presented. Located at the anterior of the pharynx is a peripharyngeal muscle. The muscle, composed of two membrane bounded smooth muscle strands, probably acts as a sphincter to prevent a reverse flow of food material. Finally, scanning micrographs show a single opening located dorsolaterally on the 10th segment. This opening has been interpreted as an excretory pore even though it does not occur ventrolaterally on the 11th segment as reported for other kinorhynchs.This investigation was supported in part by NIH Contract 70-4136 from the Division of Research Resources.  相似文献   

15.
A taxonomic revision, based mainly on morphological and distributional criteria, is presented for all taxa ofTrillium subgen.Phyllantherum Raf., which is characterized by sessile flowers. The 22 species recognized as valid include 17 morpho-geographical species in the eastern United States and five in the northwestern United States and California. These species form three morphological alliances that are characterized informally as “species groups.” All the taxa are described, and a key to species and varieties is provided. Five new species are described:Trillium decipiens, T. reliquum, T. foetidissimum, T. albidum, and T. kurabayashii; and a new status,T. angustipetalum (Torrey) Freeman, based onT. sessile var.angustipetalum Torrey, is proposed. Six new flower color forms are described:T. reliquum f. luteum, T. stamineum f. Iuteum, T. maculatum F. luteum, T. maculatum f. simulans, T. foetidissimum f. luteum, and T. cuneatum f. luteum. County distribution maps are included for all species and varieties, and an annotated synonymy is presented for each taxon.  相似文献   

16.
Liquid nitrogen storage systems are widely used for long term preservation of a range of microorganisms. Strains are stored in ampoules immersed in nitrogen or held in its evolving vapour. Immersion storage maximises the storage capacity of a vivostat but imposes limits on the type of ampoule that can be used. It is of vital importance that an ampoule can be sealed to prevent leakage of the nitrogen during storage. Several ampoule types are commercially avaailable but all have a number of disadvantages in use. They are costly, wasteful of space and difficult to seal reliably. An ampoule which can be simply made in the laboratory from polypropylene drinking straws has been described which is cheap, space saving and easy to seal. These ampoules have been in use for ten years without any problems and their use in the storage of over 2000 strains, predominantly fungi, is described. They have no detrimental effect on strain retrieval as shown by recovery rates after protracted storage. Straw ampoules provide a cheap and safe alternative to those ampoules that are commercially available and can be recommended for use in liquid nitrogen storage systems.  相似文献   

17.
Two new feather mite species of the genus Trouessartia Canestrini, 1899 (Analgoidea: Trouessartiidae) are described from passerines (Aves: Passeriformes) in Brazil: T. calcealgiana n. sp. from Philydor atricapillus (Wied) (Furnariidae), and T. gigaphallus n. sp. from Tyrannus melancholicus Vieillot (Tyrannidae). Both species have unique features, such as the large hook-like seta sR on trochanters III in T. calcealgiana, and the large male genitalia in T. gigaphallus, which are at least twice as long as normally found in most species of Trouessartia.  相似文献   

18.
The giant clam subfamily Tridacninae (family Cardiidae) is an important group of bivalve molluscs found throughout the Red Sea and Indo-Pacific, from East Africa to the Eastern Pacific biogeographic region. The Tridacna genus is currently revised with numerous cryptic species identified with molecular markers. New Tridacna records from the fringe of the known distribution areas are extremely useful to identify genetically unique species, geographic ranges, and to examine processes associated with species differentiation. While Tridacna maxima is abundant in French Polynesia (Central South Pacific Ocean) the larger fluted giant clam Tridacna squamosa was formerly reported only in the Austral Islands in the south. Following a recent survey that spanned 23 islands and atolls of the Society, Tuamotu and Gambier Archipelagos, the presence of T. squamosa between the Cook Islands and Pitcairn Islands is confirmed using both morphological and molecular information, suggesting a relic distribution across the Central Pacific Ocean. Tridacna squamosa is rare, but present throughout Tuamotu and Gambier. However, it remained undetected from the Society Islands, probably due to historical over-fishing. This species is valued by local inhabitants, and is sought after mainly as gifts and also for a limited local shell trade. The rarity of T. squamosa may call for conservation measures in the near future.  相似文献   

19.
A collaborative study was designed to asses two freeze-dried human plasma preparations containing anti-Treponema pallidum antibodies, 05/132 and 05/122, for their suitability as international reference reagents for syphilis serology. Both preparations are intended as replacements of the first international standard (IS) for syphilitic serum antibodies (HS). Samples were tested by eight laboratories using the T. pallidum passive particle agglutination assay (TPPA), the venereal disease research laboratory test (VDRL) and the rapid plasma reagin test (RPR). In addition a range of immunoassays was also used. The outcome of the collaborative study revealed that candidate standard 05/132 contains T. pallidum-specific IgG and IgM and is reactive in VDRL or RPR, and that 05/122 contains T. pallidum-specific IgG but is not reactive in either the VDRL or RPR test. Both 05/132 and 05/122 are reactive in the TPPA. On the basis of these results the Expert Committee on Biological Standardization of the World Health Organization designated 05/132 as the 1st IS for human syphilitic plasma IgG and IgM with a unitage of 3 IU per ampoule relative to HS and 05/122 as the 1st IS for human syphilitic plasma IgG with a unitage of 300 mIU per ampoule relative to 05/132.  相似文献   

20.
Summary The genus Themisto is represented in Atlantic Ocean waters by four different species: T. compressa, T. abyssorum, and T. libellula in the northern hemisphere and T. gaudichaudii in the southern hemisphere. Examination of morphological and electrophoretic characters has revealed that T. gaudichaudii, which was previously thought to have a bipolar distribution, in fact consist of separate species in Arctic and Antarctic waters, respectively. The Antarctic species remains as T. gauchichaudii Guérin 1828 and the oldest available name for the Arctic species is T. compressa Goes 1865. The results of the study also indicate that morphological variation within T. gaudichaudii (e.g. the compressa and bispinosa forms) is more likely to be the result of environmental influences rather than genetic differences. Electrophoretic analyses of genetic variation indicate that T. gaudichaudii from waters adjacent to both South Georgia Island and the South Shetland Islands belong to the same interbreeding population. Similar observations of homogeneity in other Antarctic pelagic animals suggest that the Antarctic circumpolar current systems promote effective genetic exchange and reduce the possibility of formation of distinct local breeding populations.  相似文献   

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