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1.
The temnodontis variety of Caligus mauritanicus Brian, 1924 described by Brian (1924) is a valid species known only from a single host species, Pomatomus saltatrix (Linnaeus). New material of this species has been examined from the same host fish caught from Abuqir Bay, Alexandria (Egypt), from Iskenderun Bay (Turkey) and from off the coast of South Africa. Using this material, C. temnodontis Brian, 1924 is redescribed and compared with related species. It is most closely related to the Indo-Pacific species C. pagrosomi Yamaguti, 1939.  相似文献   

2.
Chemical examinations of Cleistanthus collinus Roxb., a poisonous tree from India, and Cleistanthus patulus Muell. Arg. have resulted in isolation of a number of arylnaphthalide lignans and their glycosides as well as some furofuranoid lignans. While Cleistanthus gracilis Hook. f. from Thailand afforded an unusual glucoside of 2-β-hydroxy-8-azabicyclo-(5,0,2)-4β, 9β-epoxynona-5,7-diene, C. schlechteri from South Africa was the first reported source of the pimarane diterpenes. Cleistanthin A and cleistanthin B, diphyllin glycosides isolated from C. collinus were reported to exhibit cytotoxicity on several cancer cell lines. Cleistanthin A was found to cause DNA strand breaks and induce apoptosis in cultured cells while cleistanthin B caused G1 arrest and induced apoptosis in mammalian cells.  相似文献   

3.
Physiological mechanisms of adaptation to copper-induced stress in two widespread legume plants, white sweet clover (Melilotus albus Merik.) and zigzag clover (Trifolium medium L.), growing in habitats differing in the man-made pollution. An antioxidant plant defense system was activated in response to 10 mM CuSO4, which is a stress factor. Specific biochemical features related to adaptation to soil contamination with copper were observed in tested plant species. Superoxide dismutase was activated in response to stress in both species from various habitats. M. albus from the impact zone manifested the better capacity of proline accumulation as compared with plants from less polluted habitats. T. medium plants from the impact zone contained more active peroxidase. It was suggested that plants growing for a long time under stressful conditions manifest the greater tolerance to copper ions than plants, which did not experience stress or were subjected to the milder stress.  相似文献   

4.
Effect of fucoidans from the Far Eastern brown algae Laminaria japonica, L. cichoroides, and Fucus evanescens on developing embryos of the sea urchin Strongylocentrotus intermedius was studied. Fucoidans from these algae were shown to have different (immunostimulating, inhibitory) effects on the developing embryos. All studied fucoidan fractions added at the zygote stage had a stimulatory effect (acceleration of developmental stages and an increase of life spans) on the developing embryos, with differences by their effective concentrations. Many fucoidans added at the late blastula stage did not produce the stimulatory effect. The lowest number of immunostimulators (only a half of the tested substances) were present among fucoidans from L. japonica cichoriodes. The best immunostimulators that increased 2–3 times the life span of the embryos were heteropolysaccharides containing mannose or xylose apart from L-fucose. Some fucoidans at high concentrations produced an inhibitory effect; they were mainly composed of L-fucose or their monosaccharide composition included, apart from fucose, a significant amount of galactose, but no mannose. The method that we used turned out to be sensitive to structural peculiarities of charged polysaccharides, so it most likely can be applied for evaluation of their immunostimulating properties. From two variants of the experiment the most sensitive was the second one, in which polysaccharides were added at the late blastula stage.Translated from Zhurnal Evolyutsionnoi Biokhimii i Fiziologii, Vol. 41, No. 1, 2005, pp. 51–58.Original Russian Text Copyright © 2005 by Kiseleva, Shevchenko, Krupnova, Zvyagintseva.  相似文献   

5.
Data on specific features of the seismosensory system of the Lower Amur grayling Thymallus tugarinae from the Anyui River (basin of the Lower Amur) are provided. According to the number of openings in canals of the seismosensory system, individuals from the middle course significantly differ from graylings from the lower course in greater values of interpopulation diversity and fluctuating asymmetry. According to the number of pores of canals of the seismosensory system, the Lower Amur grayling differs from the East Siberian T. arcticus pallasi, Kamchatka T. a. mertensii, and Alaska T. a. signifer graylings.  相似文献   

6.
7.
Aim To propose a model (the choros model) for species diversity, which embodies number of species, area and habitat diversity and mathematically unifies area per se and habitat hypotheses. Location Species richness patterns from a broad scale of insular biotas, both from island and mainland ecosystems are analysed. Methods Twenty‐two different data sets from seventeen studies were examined in this work. The r2 values and the Akaike's Information Criterion (AIC) were used in order to compare the quality of fit of the choros model with the Arrhenius species–area model. The classic method of log‐log transformation was applied. Results In twenty of the twenty‐two cases studied, the proposed model gave a better fit than the classic species–area model. The values of z parameter derived from choros model are generally lower than those derived from the classic species–area equation. Main conclusions The choros model can express the effects of area and habitat diversity on species richness, unifying area per se and the habitat hypothesis, which as many authors have noticed are not mutually exclusive but mutually supplementary. The use of habitat diversity depends on the specific determination of the ‘habitat’ term, which has to be defined based on the natural history of the taxon studied. Although the values of the z parameter are reduced, they maintain their biological significance as described by many authors in the last decades. The proposed model can also be considered as a stepping‐stone in our understanding of the small island effect.  相似文献   

8.
The antimicrobial activity of lysosomes, a cell organelle, against a range of test microorganisms was examined in this study. The lysosomes isolated from Saccharomyces cerevisiae showed antimicrobial activity to Escherichia coli that positively correlated with the pH of the phosphate buffer as a dissolving solvent. The lysosomes from S. cerevisiae exhibited optimal activity at a concentration of 40%, at pH 4.0 of phosphate buffer, and at broad range temperature, except of over 50°C. It was also found that the lysosomes have antimicrobial activity against seven different microorganisms including E. coli. In addition, S. cerevisiae were exposed by a treatment with H2O2 and lysosomes were isolated from H2O2 exposed S. cerevisiae. We found that fluorescent intensities of each isolated lysosomes were increased depending on the increment of treated H2O2 concentration, and the lysosomes from 20 mM H2O2 treated S. cerevisiae showed higher antimicrobial activity than those from normal S. cerevisiae. Therefore, it suggests that lysosomes isolated from S. cerevisiae can be used as an antimicrobial agent. In addition, lysosomes activated by H2O2 enhanced its antimicrobial activity.  相似文献   

9.
The ecological and evolutionary dynamics of newly introduced invasive species can best be understood by identifying the source population(s) from which they originated, as many species vary behaviorally, morphologically, and genetically across their native landscapes. We attempt to identify the source(s) of the red imported fire ant (Solenopsis invicta) in the southern USA utilizing data from three classes of genetic markers (allozymes, microsatellites, and mitochondrial DNA sequences) and employing Bayesian clustering simulations, assignment and exclusion tests, and phylogenetic and population genetic analyses. We conclude that the Mesopotamia flood plain near Formosa, Argentina represents the most probable source region for introduced S. invicta among the 10 localities sampled across the native South American range. This result confirms previous suspicions that the source population resides in northern Argentina, while adding further doubts to earlier claims that the Pantanal region of Brazil is the source area. Several lines of evidence suggest that S. invicta in the southern USA is derived from a single location rather than being the product of multiple invasions from widely separated source localities. Although finer-scale sampling of northern Argentina and Paraguay combined with the use of additional genetic markers will be necessary to provide a highly precise source population assignment, our current results are of immediate use in directing future sampling and focusing ongoing biological control efforts.  相似文献   

10.
1. The distribution and location of the ciliated protozoan Lagenophrys aselli on the freshwater isopod Asellus aquaticus were studied in relation to water flow over the third pleopod surface. 2. At low densities L. aselli had a significant preference for the anterior centre of the pleopod; however, at the highest densities this preference was no longer significant. The distribution ranged from closer than random at low densities to further than random at the highest densities, and may have been a product of feeding and reproduction of L. aselli as well as the short intermoult period of the host. 3. An individual L. aselli has an effective area of both the lorica and the ciliated feeding disc. The ciliated feeding disc, when extended, may contribute to the presence of a small anterior–posterior gap being left between individuals.  相似文献   

11.
Glycoprotein IIb/IIIa complex, a platelet surface fibrinogen receptor, plays a key role in producing primary hemostasis. At present, only a single mutation in the GPIIIa gene, Leu33Pro, and a single mutation in the GPIIb gene, Ile843Ser, has been described. The mutations are known to enhance signaling functions of the receptor and are associated with the development of arterial thromboses. In the present study, we describe a novel GPIIIa mutation, which is T to G nucleotide substitution in position 1585, resulting in the replacement of Leu for Arg in position 40 of the amino acid sequence of the protein.__________Translated from Genetika, Vol. 41, No. 6, 2005, pp. 838–843.Original Russian Text Copyright © 2005 by Sirotkina, Shaydina, Vavilova, Schwartz.  相似文献   

12.
Chromatin from a uninucleate dinoflagellate, Crypthecodinium cohnii, a binucleate dinoflagellate, Peridinium balticum, and a chromophyte, Olisthodiscus luteus, was examined by nuclease digestion and the results were compared to those from vertebrates. Gel analysis of the products of staphylococcal (micrococcal) nuclease digestion revealed a DNA repeat unit of 220(±5) base pairs for O. luteus and 215(±5) for P. balticum. Limit digestion gave a core particle of 140 base pairs, revealing that these longer repeat sizes are due to longer linker regions. No repeating subunit structure was found upon electrophoresis of digests of C. cohnii nuclei. Examination of the DNA fragments produced by DNAse I digestion of nuclei isolated from P. balticum and O. luteus showed the same ladder of ten base multiples as seen in chromatin from other eukaryotes. Examination of the kinetics of digestion by DNAse II of Peridinium chromatin revealed less susceptibility when compared to DNAse I digestions while 70% of Olisthodiscus chromatin and 35% of C. cohnii chromatin was sensitive to DNAse II. These data, taken together with previous results from Euglena, indicate that while algal chromatin is similar to that of higher eukaryotes in regard to DNAse I and II action, it differs in that the linker DNA is longer. In addition, the Hl-like histone from O. luteus and P. balticum is located in the linker DNA as in higher eukaryotes.  相似文献   

13.
For thousands of years, plant based herbal medicines have been utilized by millions of people all over the world. Plant materials or products are used in different folk/traditional medical systems, such as the Chinese, African and Indian medical systems, like Siddha, Ayurveda, Unani, and Homeopathy. Tinospora cordifolia (TC) is a medicinal plant belonging to the family Menispermaceae. It is a big deciduous, climbing shrub growing prevalently in the tropical part of Indian subcontinent regions such as India, Pakistan, Nepal, Bhutan, Bangladesh and Srilanka, and in Myanmar, and China. Guduchi, Giloy, Shindilkodi, and Amritha are all the common names for this plant. Extracts from different parts of this herbal plant have been used to treat many diseases. In Ayurvedic medicine, extract from this plant is used for preparing “rasayanas”, which is known to cure diabetes, skin diseases, allergic conditions, jaundice, cardiovascular diseases, rheumatoid arthritis, poisoning, and microbial infections. T. cordifolia has a many bioactive phytochemicals that have been isolated from its aerial parts and roots. Many bioactive principles have been reported from this plant which belong to various classes like alkaloids, aliphatic compounds, diterpenoid lactones, phenolics, flavonoids, glycosides, sesquiterpenoids, lignans, steroids and polysaccharides. T. cordifolia possesses medicinal properties such as antioxidant, antiallergic, antiinflammatory, antimicrobial, antiviral, antidote, antitumor, antileprotic, antispasmodic, and antidiabetic properties. The present review will provide a comprehensive therapeutic potential of T. cordifolia.  相似文献   

14.
Summary. One of the most species-rich ant-plant mutualisms worldwide is the palaeotropical Crematogaster-Macaranga system. Although the biogeography and ecology of both partners have been extensively studied, little is known about the temporal structuring and the dynamics of the association. In this study we compared life-history traits of the specific Crematogaster (Decacrema) partner-ants and followed the development of ant colonies on eight different Macaranga host plant species, from colony founding on saplings to adult trees in a snapshot fashion. We found differences in the onset of alate production, queen number and mode of colony founding in the ant species and examined the consequences of these differences for the mutualism with the host plant. The lifespan of some host plants and their specific ant partners seemed to be well matched whereas on others we found an ontogenetic succession of specific partner ants. The partner ants of saplings or young plants often differed from specific partner ants found on larger trees of the same species. Not all specific Crematogaster species can re-colonize the crown region of adult trees, thus facilitating a change of ant species. Therefore lifespan of the ant colony as well as colony founding behaviour of the different partner ant species are important for these ontogenetic changes. The lifespan of a colony of two species can be prolonged via secondary polygyny. For the first time, also primary polygyny (pleometrosis) is reported from this myrmecophytic system.  相似文献   

15.
Evidence suggests membrane bound F1F0-ATPase complexes form stable associations such that dimers can be retrieved from detergent lysates of mitochondria isolated from a range of sources including algae, higher plants, yeast and bovine heart, and plant chloroplasts. The physiological relevance of these interactions is not clear but may be connected with the formation and structure of mitochondrial cristae. We sought to demonstrate, in vivo, the association of F1F0-ATPases in yeast cells co-expressing two b subunits each fused at its C-terminus to a GFP variant appropriate for fluorescence resonance energy transfer (FRET; BFP as the donor and GFP as the acceptor fluorophore). Both subunit b-GFP and b-BFP fusions were assembled into functional complexes. FRET was observed from enzyme complexes in molecular proximity in respiring cells providing the first demonstration of the association, in vivo, of F1F0-ATPase complexes. Moreover, FRET was observed within cells lacking the dimer specific subunit e, indicating structured associations can occur within the inner membrane in the absence of subunit e.  相似文献   

16.
Toxocysts of the genus Pleurotus are blastoconidia-like ovoid structures surrounded by a liquid droplet containing a toxin that paralyzes nematodes. This study investigated toxocyst development using a strain S396 of Pleurotus cystidiosus subsp. abalonus (subgen. Coremiopleurotus). The surface of the liquid droplet was found to be an elastic envelope. When a nematode touches the toxocyst, the envelope adheres to the worm and bursts. Toxocysts are induced simultaneously with coremia formation in the absence of nematodes and developed only from aerial hyphae in which nuclear division had ceased. In the early stage of toxocyst development, liquid springs repeatedly from the tip of the sterigma-like stipe before ovoid (blastoconidium-like structure) formation. A certain substance in the liquid might polymerize to form the envelope while the ovoid simultaneously budded in the droplet. The nucleus tends to locate near the toxocyst, especially in early stage of toxocyst development. Each dikaryotic cell predominantly formed one or two toxocyst(s) while each monokaryotic cell predominantly formed one. In rare cases, a nucleus existed in the toxocyst, suggesting the possibility that the toxocyst is a vestigial blastoconidium.  相似文献   

17.

Background  

Imprinted genes are exclusively expressed from one of the two parental alleles in a parent-of-origin-specific manner. In mammals, nearly 100 genes are documented to be imprinted. To understand the mechanism behind this gene regulation and to identify novel imprinted genes, common features of DNA sequences have been analyzed; however, the general features required for genomic imprinting have not yet been identified, possibly due to variability in underlying molecular mechanisms from locus to locus.  相似文献   

18.
Fossil, subfossil, and recent materials of moose from the southeast of Western Siberia, including the remains of the skull, antlers, mandibles, and postcranial skeleton, has been analyzed. Adaptive features revealed in the structure of the mandible (a high pars dentalis) suggest that forests were a less typical habitat for ancient moose, compared to recent A. a. alces. The high pars dentalis of the mandible and the shape of antlers, with a long basal part and bifurcated spatula, are indicative of their close relation to A. americanus from Eastern Siberia. Thus, moose from the Late Neopleistocene and Holocene appear to represent the same species as A. americanus. It cannot be excluded, however, that A. cf. alces is a special type of European A. a. alces moose in which the characters convergent to Eastern Siberian A. americanus developed independently, due to habitation in similar open (forest-steppe and steppe) landscapes.  相似文献   

19.
The origin of the genus Homo in Africa signals the beginning of the shift from increasingly bipedal apes to primitive, large-brained, stone tool-making, meat-eaters that traveled far and wide. This early part of the human genus is represented by three species: Homo habilis, Homo rudolfensis, and Homo erectus. H. habilis is known for retaining primitive features that link it to australopiths and for being the first stone tool makers. Little is known about H. rudolfensis except that it had a relatively large brain and large teeth compared to H. habilis and that it overlapped in time and space with other early Homo. Our understanding of the paleobiology and evolution of the larger-brained H. erectus is enhanced due to its rich fossil record. H. erectus was the first obligate, fully committed biped, and with a body adapted for modern striding locomotion, it was also the first in the human lineage to disperse outside of Africa. The early members of the genus Homo are the first to tip the scale from the more apish side of our evolutionary history toward the more human one.  相似文献   

20.
The fire blight susceptible apple cultivar Malus × domestica Borkh. cv. ‘Gala’ was transformed with the candidate fire blight resistance gene FB_MR5 originating from the crab apple accession Malus × robusta 5 (Mr5). A total of five different transgenic lines were obtained. All transgenic lines were shown to be stably transformed and originate from different transgenic events. The transgenic lines express the FB_MR5 either driven by the constitutive CaMV 35S promoter and the ocs terminator or by its native promoter and terminator sequences. Phenotyping experiments were performed with Mr5‐virulent and Mr5‐avirulent strains of Erwinia amylovora, the causal agent of fire blight. Significantly less disease symptoms were detected on transgenic lines after inoculation with two different Mr5‐avirulent E. amylovora strains, while significantly more shoot necrosis was observed after inoculation with the Mr5‐virulent mutant strain ZYRKD3_1. The results of these experiments demonstrated the ability of a single gene isolated from the native gene pool of apple to protect a susceptible cultivar from fire blight. Furthermore, this gene is confirmed to be the resistance determinant of Mr5 as the transformed lines undergo the same gene‐for‐gene interaction in the host–pathogen relationship Mr5–E. amylovora.  相似文献   

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