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Nucleotide sequence of a 5S ribosomal RNA gene in the sea urchin Lytechinus variegatus. 总被引:2,自引:12,他引:2 下载免费PDF全文
The nucleotide sequence of a cloned DNA fragment corresponding to a gene for 5S ribosomal RNA from the sea urchin Lytechinus variegatus has been determined. This sequence is representative of the dominant species of 5S rRNA labelled in vivo with 32pO4 during the cleavage stage of Lytechninus embryonic development. 相似文献
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Abstract. In vitro and in vivo studies confirmed endocytic activity of free phagocytic amebocytes in Lytechinus variegatus . Amebocytes in the perivisceral coelom were labeled with injected ferritin, and ferritin-labeled amebocytes were found in the peristomial connective tissue only one hour after injection of India ink or yeast into this tissue. The presence of ferritin inside the amebocytes indicates that these cells migrated from the perivisceral coelom to the peristomial connective tissue. After 24 hours, particles of India ink or yeast were observed inside the ferritin-labeled amebocytes, indicating the amebocytes' ability to respond to an inflammatory stimulus. These were the only inflammatory cells found in L. variegatus , using the above mentioned stimuli and time spans. 相似文献
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The Endo16 gene encodes a large extracellular protein with several functional domains that provide some insight into the role of this protein during embryonic development. We isolated the full-length cDNA sequence from Lytechinus variegatus and utilized morpholinos to further investigate the role of Endo16 during embryonic development in this species. Endo16-deficient embryos failed to undergo gastrulation and the blastocoele became filled with dissociated cells after 24 h of incubation. Moreover, there was a delay in endoderm differentiation as assayed by staining with an antibody that recognizes Endo1. The differentiation of other cell types including oral ectoderm, primary mesenchymal cells (PMC) and secondary mesenchymal cells (SMC) appeared to be normal, although the patterns of protein expression did not resemble control embryos due to the gross morphological abnormalities elicited by the LvEndo16 morpholino. Microinjection of full-length EGFP mRNA with the LvEndo16 morpholino-targeted sequence confirmed that this phenotype can be attributed specifically to the loss of Endo16 protein. Taken together, our data suggest that Endo16 may be required for the cell-extracellular matrix (ECM) interactions that are required for endoderm differentiation in the sea urchin embryo. 相似文献
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D J Veis T M Albinger J Clohisy M Rahima B Sabsay A Veis 《The Journal of experimental zoology》1986,240(1):35-46
The teeth of the sea urchin Lytechinus variegatus grow continuously. The mineral phase, a high magnesium calcite, grows into single crystals within numerous compartments bounded by an organic matrix deposited by the odontoblasts. Electron microscopic examination of glutaraldehyde-fixed Ethylene Diamine Tetra acetic acid (EDTA) demineralized teeth shows the compartment walls to be organized from multiple layers of cell membrane which might contain cytoplasmic protein inclusions. Proteins extracted during demineralization of unfixed teeth were examined by gel electrophoresis, high performance liquid chromatography, and amino acid analysis. The tooth proteins were acidic, they contained phosphoserine, and they were rich in aspartic acid. By contrast, the proteins of similarly extracted mineralized Aristotle's lantern skeletal elements were nonphosphorylated and were rich in glutamic acid. Vertebrate tooth and bone matrix proteins show similar differences. Surprisingly, an antibody to the principle rat incisor phosphoprotein showed a significant cross-reactivity with the urchin tooth protein, by dot-blot and enzyme-linked immunosorbent assay procedures. Thus, the urchin tooth proteins contain epitope regions similar to those which are phenotypic markers of vertebrate odontoblasts. Whether this is an expression of convergent or divergent evolutionary processes, it is likely that the matrix proteins play a similar role in matrix mineralization. The sea urchin tooth may thus be an excellent model for the study of odontoblast-mediated mineral-matrix relationships. 相似文献
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This paper reports results of a novel approach, X-ray microCT, for quantifying stereom structures applied to ossicles of the sea urchin Lytechinus variegatus. MicroCT, a high resolution variant of medical CT (computed tomography), allows noninvasive mapping of microstructure in 3-D with spatial resolution approaching that of optical microscopy. An intact pyramid (two demipyramids, tooth epiphyses, and one tooth) was reconstructed with 17 microm isotropic voxels (volume elements); two individual demipyramids and a pair of epiphyses were studied with 9-13 microm isotropic voxels. The cross-sectional maps of a linear attenuation coefficient produced by the reconstruction algorithm showed that the structure of the ossicles was quite heterogeneous on the scale of tens to hundreds of micrometers. Variations in magnesium content and in minor elemental constitutents could not account for the observed heterogeneities. Spatial resolution was insufficient to resolve the individual elements of the stereom, but the observed values of the linear attenuation coefficient (for the 26 keV effective X-ray energy, a maximum of 7.4 cm(-1) and a minimum of approximately 2 cm(-1) away from obvious voids) could be interpreted in terms of fractions of voxels occupied by mineral (high magnesium calcite). The average volume fraction of mineral determined for a transverse slice of the demipyramid near where it joins an epiphysis was 0.46; for a slice 3.3 mm adoral it was 0.70. Local volume fractions of mineral approached 1, and, away from resolvable voids, considerable portions of the demipyramids had volume fractions of calcite at or below approximately 0.33. MicroCT imaging of a demipyramid before and after infiltration with a high absorptivity fluid (sodium polytungstate) confirmed the determination of the volume fractions of minerals. 相似文献
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1. Urease from a sea urchin Lytechinus variegatus, was purified 300-fold, using heat precipitation, ethanol precipitation and gel filtration. 2. The pH optimum is 8.0. 3. The apparent Michaelis constant for urea is 0.13 mM at pH 8.0. 4. The inhibitory effects of seven reagents on urease were evaluated. The pattern of inhibition is similar to other invertebrate ureases. 5. L. variegatus urease is compared with that of several other invertebrates, and its possible significance in CaCO3 formation is discussed. 相似文献
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J. Christopher Taylor A.L. Lawrence Stephen A. Watts 《Marine and Freshwater Behaviour and Physiology》2014,47(6):415-428
It is suggested that gonad color in sea urchins depends upon the in vivo accumulation and metabolism of red and yellow carotenoid pigments. We hypothesized that differential light exposure could affect carotenoid deposition and, hence, gonad color in sea urchins. We therefore performed two experiments to determine whether light spectra affect the gonad color of Lytechinus variegatus. In the first experiment, urchins were fed a formulated feed supplemented with or without β-carotene and held beneath three lighting regimes designed to emit differing wavelengths of the visible spectrum. After 12 weeks, urchins were dissected and gonad color (CIE L*a*b*) was measured with a Pantone Capsure RM200. Actinic light significantly increased the value of a* (red) in gonad color. Color in the orange and yellow spectra in the gonads increased in individuals fed the β-carotene supplemented diet. In the second experiment, we cultured urchins for nine weeks under lamps specialized to emit UV radiation. All urchins in this experiment received diets supplemented with β-carotene. There was no significant difference in harvested gonad color between these treatments. These data suggest that light quality and dietary carotenoids affect carotenoid deposition in the gonads. 相似文献
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Jennings NA Pezzementi L Lawrence AL Watts SA 《Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology》2008,149(3):401-409
Acetylcholinesterase (AChE) in the echinoid Lytechinus variegatus has been characterized. Kinetic parameters V(max), K(m), K(ss), and b were 2594+/-1048 nmol ATCh hydrolyzed/min/mg tissue wet weight, 185+/-11 microM, 308+/-100 mM, and 0.2, respectively for the substrate ATCh and 17.8+/-6.87 nmol BTCh hydrolyzed/min/mg tissue wet weight, 654+/-424 microM, 36+/-31 mM, and 0.6, respectively for BTCh. Pharmacologic analyses were performed with four inhibitors of cholinesterases, physostigmine, BW284c51, ethopropazine, and iso-OMPA, and yielded IC(50) values of 106+/-4 nM, 718+/-118 nM, 2.57+/-0.6 mM, and >0.0300 M, respectively. Both kinetic and pharmacologic results confirmed the existence of AChE in larval L. variegatus. Dimeric and tetrameric globular forms (determined by velocity sedimentation on sucrose gradients) were present in L. variegatus larvae. Activity of AChE increased significantly as larvae progressed in development from embryos to eight-arm larvae. Acetylcholinesterase activity of F1 larvae derived from sea urchins collected from wild populations and of F1 larvae derived from sea urchins cultured in the laboratory and fed two different diets suggest that the nutritional and/or environmental history of the adult sea urchin affect the developmental progression of AChE activity in the F1 offspring. 相似文献
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The 3'-terminus of 26 S rRNA from the sea urchin Lytechinus variegatus has been determined by oligonucleotide fingerprinting, S1 nuclease mapping and terminal nucleotide analysis. There are two species of 26 S rRNA of approximately equal abundance, one 19 nucleotides longer than than other. 相似文献
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Correlative ultrastructural and electrophysiological studies of sperm-egg interactions of the sea urchin, Lytechinus variegatus 总被引:5,自引:0,他引:5
The sequence of ultrastructural events following the onset of the sperm-induced conductance increase in eggs of the sea urchin, Lytechinus variegatus, was investigated. Eggs voltage clamped at -20 mV were fixed 1 to 20 sec after onset of the conductance increase caused by single sperm. Continuity between the plasma membranes of the sperm and egg was first detected 5 sec after onset of the conductance increase. The earliest stages of formation of the fertilization cone coincided with the establishment of continuity of the gamete plasma membranes. At 6 to 8 sec after the initial conductance increase cortical granule dehiscence was first observed in the immediate vicinity where continuity of the gamete plasma membranes had occurred. These observations are consistent with the conclusion that opening of ion channels at fertilization precedes fusion of the sperm and egg plasma membranes, while exocytosis of cortical granules is initiated following fusion of the sperm and egg plasma membranes. 相似文献
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Levitan DR 《Proceedings. Biological sciences / The Royal Society》2000,267(1443):531-534
The theoretical prediction that fast sperm should be more effective at fertilizing eggs has never been documented empirically. Interspecific comparisons suggest an inverse relationship between sperm velocity and sperm longevity but this trade-off has never been demonstrated within a species. Here I investigate how sperm velocity and sperm longevity influence the patterns of fertilization in the sea urchin Lytechinus variegatus. In the laboratory I examined 11 male female pairs of sea urchins for variation in sperm velocity and sperm longevity, and determined the correlations of these traits with the percentage of eggs fertilized with serially diluted sperm. Males with faster sperm had higher rates of fertilization than males with slower sperm. Within individual males, as sperm aged they slowed down and showed a reduced percentage activity and lower rates of fertilization. Across males, the average velocity of freshly spawned sperm was inversely related to sperm longevity. These results establish the possibility that sperm traits are adapted for varying conditions along a continuum from sperm limitation to sperm competition. 相似文献
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T T?nnesen 《Cytobiologie》1978,16(3):451-479
In the present communication a characterization of the 5 S rRNA genes and the tRNA genes of Tetrahymena pyriformis has been performed. The number of 5 S rRNA and tRNA genes in the macromolecular DNA has been established. Furthermore no sequence homology is observed for these genes. The number of both types of genes does not change significantly under starvation conditions. The genomic organization of the 5 S rRNA and tRNA genes has been investigated. From in vivo replication studies it is concluded, that replication of both 5 S rRNA and tRNA genes takes place throughout the whole S-period. 相似文献