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A new member of the chlorophycean, tetrasporalean genus Palmellopsis Korschikov (1953), Palmellopsis muralis Bold and King, is described from limestone in Austin, Texas, U.S.A. Certain details of ultrastructural organization are included.  相似文献   

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ABSTRACT. The structure and ultrastructure of the chitinous lorica of Eufolliculina sp. are described. The lorica is produced from precursor material secreted by the motile swarmer immediately after settling. This material is located in numerous vesicles found in the cortical region of the cells and is secreted by exocytosis. Initially, material is secreted from the ventral part of the cell to produce the attachment plate of the lorica. After this, exocytosis occurs over most of the body surface as the ampulla part of the lorica is constructed. During the later stages of lorica formation, secretion is mainly limited to the anterior of the cell as the neck is formed. The lorica is shaped mainly by the action of the cilia and by the behavior of the cell. While the neck is being formed, the anterior part of the cell is deformed by a local accumulation of cytoplasmic vacuoles. This deformation is employed in shaping the neck. No changes were detected in the organization of the cortical infraciliature during the first stages of lorica formation, but they do occur after the neck has been produced and as the swarmer develops into the sessile form.  相似文献   

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A new species of Dudresnaya is described from Puerto Rico and Georgia. Gametophytes have cylindrical axes, exserted apical cells, rectangular to hexagonal crystals in the axial cells, ellipsoidal outer assimilatory cells, spermatangial mother cells which are terminal or subterminal cells of the subdichotomously branched outer assimilatory branches and auxiliary cells which are indistinguishable in appearance from adjacent, large, deeply staining cells of the auxiliary cell branch. Tetrasporophytes are unknown.  相似文献   

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ABSTRACT. A new species of Herpetomonas was isolated from the intestinal tract of a mosquito, Haemagogus janthinomys, in French Guiana (South America). Ultrastructure, growth in various culture media, and morphological changes are presented. The name, Herpetomonas dedonderi, is proposed for this new species of lower trypanosomatid.  相似文献   

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The genus Aurelia is one of the major contributors to jellyfish blooms in coastal waters, possibly due in part to hydroclimatic and anthropogenic causes, as well as their highly adaptive reproductive traits. Despite the wide plasticity of cnidarian life cycles, especially those recognized in certain Hydroza species, the known modifications of Aurelia life history were mostly restricted to its polyp stage. In this study, we document the formation of polyps directly from the ectoderm of degenerating juvenile medusae, cell masses from medusa tissue fragments, and subumbrella of living medusae. This is the first evidence for back-transformation of sexually mature medusae into polyps in Aurelia sp.1. The resulting reconstruction of the schematic life cycle of Aurelia reveals the underestimated potential of life cycle reversal in scyphozoan medusae, with possible implications for biological and ecological studies.  相似文献   

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Errata (vol. 1)     
《Ecological Research》1987,2(1):100-100
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A variety of types of human B-cell lines were evaluated for their ability to produce interleukin 1 (IL-1)-like factors. All of the eight Epstein-Barr virus (EBV)-transformed B lymphocyte lines, three of four of the EBV+ lymphoma lines, only three of seven of the EBV- lymphoma lines, and none of the three tested myeloma lines secreted some IL-1 activity. The IL-1-like factor produced by the cell lines was detected on the basis of its thymocyte comitogenic and/or fibroblast proliferative activities. Injections of partially purified IL-1-like factor from one of the EBV-transformed B-lymphocyte lines also induced the appearance of an acute phase protein (haptoglobin) in the serum of C3H/HeJ mice. These biological activities are identical with those of monocyte-derived IL-1. Thymocyte comitogenic activity and fibroblast proliferation activity from one of the EBV-B cell line-derived IL-1-like activities were not dissociable by biochemical procedures, including HPLC gel filtration and HPLC anion-exchange chromatography. However, the IL-1-like factor from one of the EBV-B lymphocyte cell lines was larger in size (25 kDa) and more acidic (pI 5.5) than monocyte-derived IL-1.  相似文献   

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A mentally retarded girl with a 46,XX/47, XX+r(1) (p11q22q22p11)/47, XX+r(1) (p11q22) fra(1) (p31) fra(1) (p11) fra(1) (q22) karyotype who inherited the fragile sites from the normal mother was studied. The conicidence of fra(1) (p11) and fra(1) (q22) with the ring chromosome breakpoints strongly suggests a cause-effect relationship. This finding agrees with other reported associations between fragile sites and structural chromosome abnormalities and constitutes the fourth reported of a de novo structurally abnormal chromosome as a consequence of presumed in vivo fragile sites instability. Although risk figures for chromosome anomalies and cancer associated with fragile sites are lacking, carriers of fra (1) (p11) may have a higher risk for abnormalities of chromosome 1 in somatic and gonadal cells than the general population.  相似文献   

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(1-->3)-beta-D-Glucans have been recognized as a potential causative agent responsible for bioaerosol-induced respiratory symptoms observed in both indoor and occupational environments. A specific enzyme immunoassay was developed to quantify (1-->6) branched, (1-->3)-beta-D-glucans in environmental samples. The assay was based on the use of a high-affinity receptor (galactosyl ceramide) specific for (1-->3)-beta-D-glucans as a capture reagent and a monoclonal antibody specific for fungal cell wall beta-D-glucans as a detector reagent. The assay was highly specific for (1-->6) branched, (1-->3)-beta-D-glucans (such as that from Saccharomyces cerevisiae) and did not show any response at 200 ng/ml to curdlan, laminarin, pustulan, dextran, mannan, carboxymethyl cellulose, and endotoxins. The detection level was 0.8 ng/ml for baker's yeast glucan and Betafectin. A coefficient of variation of 7.8% was obtained for (1-->3)-beta-D-glucans in house dust samples. Metal working fluids spiked with (1-->3)-beta-D-glucans inhibited the glucan assay. Because the assay is specific for (1-->6) branched, (1-->3)-beta-D-glucans and is sensitive and reproducible, it will be useful for the investigation of health effects from exposure to this class of biologically active molecules.  相似文献   

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The photophysical behaviour of a new pyrene derivative, 1-(4-N,N-dimethylaminophenylethynyl)pyrene (DMAPEPy), in various solvents has been studied. Due to the presence of an ethynyl link with a cylindrical pi cloud between the donor (N,N-dimethyl group) and the acceptor (pyrene), the molecule shows efficient intramolecular charge transfer, with a high extinction coefficient in all the solvents. There is significant solvatochromism in the fluorescence with a large increase in the Stokes' shift of around 125 nm between n-hexane and acetonitrile. The solvent-dependent spectral data show a good correlation with the Kamlet-Taft solvent polarity parameter (pi*). The plots of Stokes' shifts with E(T)(30) are linear for non-protic solvents and for protic solvents but with different slopes. The fluorescence quantum yields are high for non-polar solvents and decrease as the solvent polarity increases. Unlike the parent molecule pyrene, DMAPEPy shows a short lifetime, which is fairly insensitive to oxygen-induced quenching and is dependent on solvent polarity. The molecule shows high steady-state fluorescence anisotropy, which is very sensitive to the viscosity change of the medium.  相似文献   

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