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1.
The cDNA encoding about half of an antigenic non-surface schistosome parasite protein of M r 97 K has recently been cloned and sequenced (Lanar, Pearce, James and Sher (1986)Science 234:593–596). Analysis of this sequence, together with the properties of the native protein, reveals that this protein is paramyosin, the hitherto unsequenced core protein of myosin filaments in invertebrate muscle. In this report we analyze in more detail the partial amino acid sequence of schistosome paramyosin and describe electron microscope studies of the native protein and its aggregates. We show a close correspondence between the structures of paramyosin and the myosin rod that is required for these proteins to assemble together in muscle thick filaments.  相似文献   

2.
利用甘油梯度离心方法分离和纯化螯虾腹屈肌粗肌丝,电子显微镜照片显示粗肌丝上有数条纵行条纹,指示其可能由数根亚丝所组成。粗肌丝的 SDS-聚丙烯酰胺凝胶电泳表明其含有肌球蛋白和副肌球蛋白,肌球蛋白仅包含有二种轻链。副肌球蛋白类晶体呈针状,具有14.5nm 和72.5nm 的横纹周期。实验结果表明,螯虾腹屈肌粗肌丝是肌球蛋白-副肌球蛋白丝。  相似文献   

3.
Bivalve molluscs can bioaccumulate, in their tissues, well known viruses that infect humans and higher animals. However, since 1969 there have been reports, based largely on ultrastructural studies, that have indicated there are also viruses which infect these molluscs. Lack of bivalve molluscan cell lines has limited the isolation of these viruses, although some viruses isolated in fish cell lines are claimed to be infective for bivalves. Distinctive morphogenesis and characteristics of iridoviruses have been reported in larval and adult oysters in association with infections of epithelial and haemocytic tissues. Herpes viruses have been reported in the American oyster, Pacific oyster, and European flat oyster from three continents. The herpes viral agent in Pacific oysters has been experimentally transmitted and requires temperatures of 25–26°C for a productive infection and clinical disease. Papova-like viruses, picorna-like, and other small virus-like particles have been reported in several bivalve species. A leukemia-like disease of many bivalve species, collectively termed disseminated neoplasias, is of unconfirmed aetiology, but may be related to retroviral infections. Representatives of the Reoviridae and Birnaviridae have been isolated by using fish cell lines. One definitive study concludes that at least one example is not infective for bivalves while other studies claim molluscan infectivity. Phages have been reported in three pathogenic agents infecting bivalves. Advancement in the field of molluscan virology will require increased application of physical isolation methods, refinement of primary cell culture methods, use of molecular diagnostic tools, and the development of continuous molluscan cell lines.  相似文献   

4.
Artificial neural networks (ANNs) have become increasingly sophisticated and are widely used for the extraction of patterns or meaning from complicated or imprecise datasets. At the same time, our knowledge of the biological systems that inspired these ANNs has also progressed and a range of model systems are emerging where there is detailed information not only on the architecture and components of the system but also on their ontogeny, plasticity and the adaptive characteristics of their interconnections. We describe here a biological neural network contained in the cephalopod statocysts; the statocysts are analogous to the vertebrae vestibular system and provide the animal with sensory information on its orientation and movements in space. The statocyst network comprises only a small number of cells, made up of just three classes of neurons but, in combination with the large efferent innervation from the brain, forms an 'active' sense organs that uses feedback and feed-forward mechanisms to alter and dynamically modulate the activity within cells and how the various components are interconnected. The neurons are fully accessible to physiological investigation and the system provides an excellent model for describing the mechanisms underlying the operation of a sophisticated neural network.  相似文献   

5.
, , , and 1992. Cloning and partial nucleotide sequence of Schistosoma japonicum paramyosin: a potential vaccine candidate against schistosomiasis. International Journal for Parasitology 22: 1187–1191. Paramyosin from the blood fluke, Schistosoma mansoni, has shown promise as a vaccine candidate for schistosomiasis mansoni. Here we report the cloning and partial nucleotide sequence of a cDNA encoding paramyosin from the related human parasite, Schistosoma japonicum. Affinity purified antibodies to this clone recognized a S. japonicum antigen of molecular weight 97 kDa, equivalent to the reported size of S. mansoni paramyosin. Alignment of the cDNA sequence with that of S. mansoni paramyosin revealed 90% identity. Comparison of the predicted amino acid sequences revealed 95% identity. Although these two parasites differ in many characteristics, the substantial homology demonstrated here between S. mansoni and S. japonicum paramyosin could have important implications for the development of a S. japonicum vaccine.  相似文献   

6.
    
Integrins play a key role in the intermediation and coordination between cells and extracellular matrix components. In this study, we first determined the presence of the β integrin‐like protein and its presumptive ligand, fibronectin‐like protein, during development and in some adult tissues of the bivalve mollusc Mytilus trossulus. We found that β integrin‐like protein expression correlated with the development and differentiation of the digestive system in larvae. Besides the presence of β integrin‐like protein in the digestive epithelial larval cells, this protein was detected in the hemocytes and some adult tissues of M. trossulus. The fibronectin‐like protein was detected firstly at the blastula stage and later, the FN‐LP‐immunoreactive cells were scattered in the trochophore larvae. The fibronectin‐like protein was not expressed in the β integrin‐positive cells of either the veliger stage larvae or the adult mussel tissues and the primary hemocyte cell culture. Despite the β integrin‐ and fibronectin‐like proteins being expressed in different cell types of mussel larvae, we do not exclude the possibility of direct interaction between these two proteins during M. trossulus development or in adult tissues.  相似文献   

7.
    
A simple but effective coupling of microdialysis and capillary electrophoresis with laser induced fluorescence detection technique was applied to analysis of amino acid neurotransmitters in the hypothalamus of rats after acute exhausting exercise. The separation of amino acids was achieved using an uncoated fused-silica capillary (57 cm×75 μm I.D.) with a buffer of 10 mM disodium tetraborate at pH 10 and an applied voltage of 12.5 kV. The detection limit was 10−10 M for each amino acid. It is sufficiently sensitive and rapid for the determination of amino acids in a 5-μl Microdialysate. In comparison to pre-exercise, a significant increase in the levels of six hypothalamic amino acids (arginine, glycine, lysine, glutamic acid, alanine, γ-amino-n-butyric acid) was found after exercise. These results demonstrate that the increase of metabolic amino acids in the hypothalamus of rats can be induced by exhausting exercise and suggests that amino acid neurotransmitters may play functional roles in the central effects of exercise.  相似文献   

8.
    
Heliminthic paramyosin is a multifunctional protein that not only acts as a structural protein in muscle layers but as an immune-modulatory molecule interacting with the host immune system. Previously, we found that paramyosin from Clonorchis sinensis (CsPmy) is bound to human complement C9 protein (C9). To analyze the C9 binding region on CsPmy, overlapping recombinant fragments of CsPmy were produced and their binding activity to human C9 was investigated. The fragmental expression of CsPmy and C9 binding assays revealed that the C9 binding region was located at the C-terminus of CsPmy. Further analysis of the C-terminus of CsPmy to narrow the C9 binding region on CsPmy indicated that the region flanking 731Leu–780Leu was a potent C9 binding region. The CsPmy fragments corresponding to the region effectively inhibited human C9 polymerization. These results provide a precise molecular basis for CsPmy as a potent immunomodulator to evade host immune defenses by inhibiting complement attack.  相似文献   

9.
This paper presents the results of the analysis of density dynamics of the larvae of the Pacific mussel in plankton, and experimental data on their settling on collectors in Vostok Bay, Sea of Japan, obtained in May–September 1989. It was found that, in the summer-autumn season, complex demographic processes occur on the suspended anthropogenic substrata. These processes are caused by the primary settling of pelagic larvae and by the secondary settling of juvenile mussels.  相似文献   

10.
    
Mollusc shells, beyond the treasure of information inherently conveyed through their morphology and chemical composition also have the capacity to preserve DNA sequences over the long term in their inner structure. This has been clearly demonstrated for the first time in the study published in this issue of Molecular Ecology Resources by Der Sarkissian et al. ( 2017 ). With a methodology specifically dedicated to ancient DNA and solid matrices, the authors were able to successfully extract and amplify DNA from marine shells spanning the last 7,000 years. Furthermore, using metagenomic analyses, they could identify important factors affecting DNA recovery. Using reference genomes and sequences in a targeted approach to assign high‐throughput sequencing reads, the authors revealed both the presence of endogenous mollusc DNA and a potent pathogen of Manilla clam. Collectively, the results presented in this study open extremely promising research avenues, from palaeogenomics and evolutionary biology to ecological genomics at population and community levels, as well as the opportunity to fine‐tune diagnostic tools for conservation and aquaculture purposes. Last but not least, this study also offers exciting perspectives in epigenomics and the evolution of regulatory processes in the context of adaptation to global change. It can be easily expected that the approach developed by Der Sarkissian et al. ( 2017 ) will be pursued and extensively investigated in the near future by the scientific community interested in these issues.  相似文献   

11.
    
This study aimed to describe the gonadal histology and the reproductive cycle of Crassostrea brasiliana in the mangroves of Guaratuba Bay in southern Brazil. Adults were collected monthly from January 2010 to April 2011 from three sampling sites in intertidal oyster beds. The animals were evaluated using biometric and histological analyses of the gonads. The gonadal tissue samples were processed according to the standard histological procedures, and permanent slides were prepared using Harris' haematoxylin and eosin. The oysters were identified at the species level using a molecular protocol. Females (69%) predominated over males (26%), with 4% indeterminate and 1% hermaphroditic. Mature females were more prevalent in February, March and December 2010 and in March 2011. Mature males were more prevalent in February and April 2010 and in March 2011. The presence of hermaphroditic individuals was sporadic, and oysters in immature stages or sexual repose were observed in only a few collections between the months of May and October 2010. The reproduction of C. brasiliana in Guaratuba Bay occurs intermittently, but with greater intensity during the summer, with a larger number of females produced.  相似文献   

12.
    
A report is presented here on the simultaneous occurrence of two developmental strategies, i.e. planktonic larvae and advanced development in Tonna gatea.  相似文献   

13.
The scavenger receptor recognized as a multiligand family of receptors falls in the group that is internalised through endocytosis. In this report we used several recombinant fragments of the tapeworm protein paramyosin, known to form filamentous dimers that bind collagenous structures as ligands of different length for the class A type I scavenger receptor (SR-AI). While native CHO cells are unresponsive to any of the recombinant fragments, it is shown that CHO cells transfected with this receptor efficiently internalise recombinant fragments that correspond to two thirds of the full-length paramyosin. In contrast, recombinant products corresponding to one-third of the full-length paramyiosin are not internalised. It is also shown that important molecules in the organization of the coated pit, are enriched when the two-thirds long paramyosin fragments were bound and internalised through the SR-AI. Moreover, internalisation of these fragments trigger a classical apoptotic pathway shown by the presence of TUNEL positive cells and the appearance of apoptotic bodies. We report paramyosin as a new ligand for the scavenger receptor and provide evidence supporting the notion that these receptors upon the formation of arrays with length-specific molecules, not only trigger endocytosis but also seem to regulate the synthesis of molecules involved in the organization of coated pits. (Mol Cell Biochem 271: 123–132, 2005)  相似文献   

14.
The ability of neurons in the abdominal ganglion of Aplysia to regenerate their axons following branchial nerve crush was studied using retrograde staining and intracellular dye injection. The duration of the gill withdrawal reflex (GWR) was measured prior to and following nerve crush. Three days after crushing the nerve, the duration of the gill withdrawal reflex was reduced to 20% of control levels. There was rapid recovery 19 days after crushing the branchial nerve. The GWR duration returned to control levels by postlesion days 25–27. Some of the behavioral recovery can be attributed to axonal regeneration. Regeneration, as evidenced by retrograde staining, was first observed by postlesion day 15. The number of stained neurons in ganglia with crushes increased until postlesion day 33. The number of stained neurons in experimental animals was always less than that of controls (67 ± 9% at postlesion day 56). More axonal regeneration was seen in the hemiganglion ipsilateral to the branchial nerve. Regeneration after 32 days postlesion was 60 ± 5% of controls in the ipsilateral hemiganglion, as opposed to 29 ± 6% in the contralateral hemiganglion. Regeneration of individual neurons was also demonstrated. Identified neuron R2 was shown by intracellular dye injection and electrical stimulation of antidromic action potentials to have an axon in the branchial nerve in all ganglia allowed to regenerate for longer than 32 days. These results indicate that in Aplysia, despite behavioral recovery, complete axonal regeneration does not occur in a large segment of the neurons in the adult central nervous system. © 1998 John Wiley & Sons, Inc. J Neurobiol 35: 160–172, 1998  相似文献   

15.
S Hunt  K Oates 《Tissue & cell》1984,16(4):565-575
The periostracum of the marine gastropod Buccinum has a helicoidal arrangement of its principal constituent which is a fibrous protein (Hunt and Oates, 1978). Chitin, chemically and physically identified, is present at a concentration of about 6% of the dry weight and can be seen in dispersates of whole periostracum as long fibrils and ribbons between 3 and 14 nm diameter. Deproteinization with hot alkali removes all protein leaving a chitinous 'ghost' of the periostracum. Dispersates, examined negatively stained, show only chitin fibrils and ribbons while sectioned material demonstrates a tenuous, part orthogonal, part helicoidal, architecture based on the chitin residue. The relative roles of the protein and polysaccharide components is speculated upon and comparisons with arthropod cuticle drawn.  相似文献   

16.
    
Abstract. Telomerase is a ribonucleoprotein that can maintain telomeres, the repetitive sequences of DNA found at the end of eukaryotic chromosomes, and confer long-term proliferative capacity on cells. Telomerase expression is essential during periods of intense cell division such as the early developmental process. In later development, some species retain telomerase activity while others repress telomerase activity in what is thought to be a tumor-protective mechanism. Despite the importance of telomerase expression in both development and neoplastic disease, no studies to date have characterized its expression in bivalves. We present the first report of telomerase expression in a bivalve species, the sand scallop, Euvola ziczac. Telomerase activity was detected throughout the early stages of development and in all adult tissues examined. Analysis of DNA isolated from adult tissues indicated long telomeres, with terminal restriction fragment lengths >20 kb in both somatic and germ tissues. Ubiquitous telomerase expression throughout development and into adulthood would suggest a lack of telomere-related senescence and suggests that these scallops do not use telomerase repression as a mechanism to suppress the formation of neoplasm.  相似文献   

17.
We found out a new protein from natural actomyosin prepared from adductor muscle of Hokki clam, bivalve shell. We isolated this protein and determined some properties. It has a large molecular weight (230 kDa) and the star diagram of amino acid composition was very similar to that of paramyosin (110 kDa). When this protein was added to Hokki clam myosin, the Mg2+-ATPase activity was more activated in the presence of 10-7 M Ca2+ and further inhibited in the presence of 10-4 M Ca2+ as compared with those of myosin. From these results, we suggest that Hokki clam adductor muscle contains another myosin-linked regulatory protein, myonin, which is different from the myosin-linked system, the myosin light chain-linked system. We named this protein myonin.  相似文献   

18.
    
Abstract. The cytokine interleukin-1β (IL-1β) mediates interactions of immune and inflammatory cells in mammals. Previous reports also have linked plasma (cell-free hemolymph) levels of IL-1β in the snail Biomphalaria glabrata to resistance against Schistosoma mansoni . In the present study, fluorescent probes were used to study larval schistosome and snail hemocyte viability during in vitro encounters. Hemolymph (plasma and hemocytes) from schistosome-susceptible (M-line) and resistant (13–16-R1) B. glabrata was added to sporocysts of S. mansoni and the viability of hemocytes and parasites was assessed. Next, IL-1β was added to sporocyst-hemolymph samples, the viability of sporocysts and hemocytes determined and then compared to control assays. The number of live sporocysts present after incubation for 1 h with hemolymph from M-line snails was significantly greater than the number seen when hemolymph from 13–16-R1 snails was tested. Nearly all sporocysts survived the 1 h incubation with M-line hemolymph, and most of the hemocytes attached to sporocysts were dead. In contrast, nearly all sporocysts were dead when hemolymph from 13–16-R1 snails was tested, and most attached hemocytes were alive. Addition of IL-1β to M-line hemolymph resulted in a dramatic increase in sporocyst death. Addition of IL-1β to 13–16-R1 hemolymph produced a small but significant increase in the rate of sporocyst death. These results indicate that the concentration of IL-1β present in hemolymph from B. glabrata is directly related to the ability of this snail to kill S. mansoni sporocysts in vitro.  相似文献   

19.
The chromatin of the spermatozoa from the bivalve molluscProtothaca thaca, has a peculiar composition in which coexist core histones with sperm-specific proteins H1 and Pt1, the latter being a protein exhibiting features intermediate between histones and protamines. In this paper, we report an analysis of chromatin organization using micrococcal nuclease digestion, salt fractionation of soluble chromatin derived from nuclease digestion and crosslinking experiments. The results obtained indicate that it is possible to obtain two types of chromatin, one which is soluble, more accessible to micrococcal nuclease action and which does not contain Pt1, and another insoluble type, more resistant to micrococcal nuclease and enriched in protein Pt1. The crosslinking experiments show that the protein Pt1 interacts with itself and with core histones but not with sperm-specific H1. These results have led us to propose a special structural arrangement for this chromatin. Based in the data reported here we propose the coexstence in the genome ofP. thaca of two interspersed chromatin domains, one nucleosomal and the other nonnucleosomal containing protein Pt1.  相似文献   

20.
上川岛潮间带不同生境底栖软体动物物种多样性初步研究   总被引:2,自引:0,他引:2  
目的:研究上川岛潮间带不同生境底栖软体动物物种多样性。方法:对上川岛潮间带(沙滩、泥沙滩、红树林泥滩、岩石滩) 4种不同生境的7个样方的底栖软体动物进行了生物多样性的初步调查。结果:共鉴定底栖软体动物14科30种,上川岛潮间带底栖软体动物物种丰富度指数为岩石滩(平均为1.784 ) >泥沙滩(平均为1.5 2 1) >红树林泥滩(平均为1.2 35 ) >沙滩(平均为0 .6 92 ) ;多样性指数岩石滩(平均为1.5 5 1) >红树林泥滩(平均为1.30 4 ) >泥沙滩(平均为1.16 2 ) >沙滩(平均为0 .4 0 3)。结论:底栖软体动物的种类及数量分布受底质、浪击等因素的影响。  相似文献   

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