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71.
Laboratory experiments were carried out to investigate byssal thread production by the intertidal mytilid mussel Hormomya mutabilis in response to effluent from the predatory crab Eriphia smithii and the starfish Coscinasterias acutispina. During the early period of the experiment, large H. mutabilis exposed to crab effluent produced a significantly smaller number of functional byssal threads than mussels in crab-free water.
No significant difference in the diameter of threads produced in the two treatments was detected. The number of functional
byssal threads produced by small H. mutabilis exposed to crab effluent did not differ significantly from that of mussels in crab-free water. However, small H. mutabilis exposed to crab effluent tended to discard fewer byssal bundles, that is, they shifted their attaching sites less frequently
than similar mussels in crab-free water. In the presence of waterborne cues from the crab, H. mutabilis tended to reduce both the secretion of byssal threads and movement across the substratum. No significant differences in behaviour
were observed between large mussels exposed to effluent from the starfish and those unexposed. The adaptive significance of
the responses shown by H. mutabilis is discussed in terms of protection against predators differing in foraging behaviour.
Electronic Publication 相似文献
72.
73.
Solar Cells: Triple‐Layer Structured Composite Separator Membranes with Dual Pore Structures and Improved Interfacial Contact for Sustainable Dye‐Sensitized Solar Cells (Adv. Energy Mater. 13/2014) 下载免费PDF全文
74.
Masayuki Adachi Masatomo So Kazumasa Sakurai József Kardos Yuji Goto 《The Journal of biological chemistry》2015,290(29):18134-18145
Although amyloid fibrils and amorphous aggregates are two types of aggregates formed by denatured proteins, their relationship currently remains unclear. We used β2-microglobulin (β2m), a protein responsible for dialysis-related amyloidosis, to clarify the mechanism by which proteins form either amyloid fibrils or amorphous aggregates. When ultrasonication was used to accelerate the spontaneous fibrillation of β2m at pH 2.0, the effects observed depended on ultrasonic power; although stronger ultrasonic power effectively accelerated fibrillation, excessively strong ultrasonic power decreased the amount of fibrils formed, as monitored by thioflavin T fluorescence. An analysis of the products formed indicated that excessively strong ultrasonic power generated fibrillar aggregates that retained β-structures but without high efficiency as seeds. On the other hand, when the spontaneous fibrillation of β2m was induced at higher concentrations of NaCl at pH 2.0 with stirring, amorphous aggregates became more dominant than amyloid fibrils. These apparent complexities in fibrillation were explained comprehensively by a competitive mechanism in which supersaturation-limited reactions competed with supersaturation-unlimited reactions. We link the kinetics of protein aggregation and a conformational phase diagram, in which supersaturation played important roles. 相似文献
75.
Kawaguchi S Kilpatrick R Roberts L King RA Nicol S 《Journal of plankton research》2011,33(7):1134-1138
For the first time the entire sequence of the mating behaviour of Antarctic krill (Euphausia superba) in the wild is captured on underwater video. This footage also provides evidence that mating can take place near the seafloor at depths of 400-700 m. This observation challenges the generally accepted concept of the pelagic lifestyle of krill. The mating behaviour observed most closely resembles the mating behaviour reported for a decapod shrimp (Penaeus). The implications of the new observation are also discussed. 相似文献
76.
77.
Comparative study of a new composite biomaterial fluor-hydroxyapatite on fibroblast cell line NIH-3T3 by direct test 总被引:1,自引:0,他引:1
Marica Theiszová Soňa Jantová Silvia Letašiová Ľuboš Valík Martin T. Palou 《Biologia》2008,63(2):273-281
The number of biomaterials used in biomedical applications has rapidly increased in the past two decades. Fluorapatite (FA)
is one of the inorganic constituents of bone or teeth used for hard tissue repairs and replacements. Fluor-hydroxyapatite
(FHA) is a new synthetically prepared composite that in its structure contains the same molecular concentration of OH− groups and F− ions. The aim of this experimental investigation was to use the embryonal mouse fibroblast cell line NIH-3T3 for comparative
study of basal cytotoxicity of fluoridated biomaterials FHA and FA discs. Hydroxyapatite (HA) disc, high-density polyethylene
as negative control and polyvinyl chloride (PVC) containing organotin stabilizer as positive control were used as standard
biomaterials. The appropriateness of the use of NIH-3T3 cells and their sensitivity for tested biomaterials were evaluated
on the basis of five cytotoxic end points: cell proliferation, cell morphology, lactate dehydrogenase (LDH) released, protein
and DNA cell content. The basal cytotoxicity of FHA, FA and HA discs was measured by direct contact method. FHA composite,
FA and HA demonstrated in cell line NIH-3T3 nearly similar basal cytotoxicity increasing with the time of treatment. After
72 h of biomaterials treatment, about 25% inhibition of cell number, unchanged morphology of dividing cells, 6.31–0.16% increase
of released LDH, about 10% inhibition of cell protein content and about 20% inhibition of DNA content was found. On the other
hand, from the growth rates it resulted that NIH-3T3 cells, affected by tested biomaterials, divided about 20% slowlier than
the control (untreated cells). Using the linear regression analysis we found out that deviations in measurements of cytotoxicity
by four methods were as follows: less than 10% for cell number, protein and DNA content methods and 12.4% for released LDH
method. Based on a good correlation of the cytotoxicity of biomaterials obtained from all end points we could conclude that
fibroblast NIH-3T3 cell line was appropriate for measuring the basal cytoxicity of tested biomaterials. 相似文献
78.
Li GQ Xia HH Chen MH Tsukamoto T Tatematsu M Gu Q Qiao L Cho CH So WH Yuen MF Hu PJ Liang YJ Lin HL Chan AO Wong BC 《Helicobacter》2008,13(1):20-29
Background: Helicobacter pylori infection is a major cause of gastritis and gastric carcinoma. Aspirin has anti‐inflammatory and antineoplastic activity. The aim of the present study was to determine the effects of aspirin on H. pylori‐induced gastritis and the development of heterotopic proliferative glands. Methods: H. pylori strain SS1 was inoculated into the stomachs of Mongolian gerbils. Two weeks after inoculation, the animals were fed with the powder diets containing 0 p.p.m. (n = 10), 150 p.p.m. (n = 10), or 500 p.p.m. (n = 10) aspirin. Mongolian gerbils were killed after 36 weeks of infection. Uninfected Mongolian gerbils (n = 10) were used as controls. Histologic changes, epithelial cell proliferation and apoptosis, and prostaglandin E2 (PGE2) levels of gastric tissue were determined. Results: H. pylori infection induced gastric inflammation. Administration of aspirin did not change H. pylori‐induced gastritis, but alleviated H. pylori‐induced hyperplasia and the development of heterotopic proliferative glands. Administration of aspirin accelerated H. pylori‐associated apoptosis but decreased H. pylori‐associated cell proliferation. In addition, the increased gastric PGE2 levels due to H. pylori infection were suppressed by treatment with aspirin, especially at the dose of 500 p.p.m. Conclusions: Aspirin alleviates H. pylori‐induced hyperplasia and the development of heterotopic proliferative glands. Moreover, aspirin increases H. pylori‐induced apoptosis. We demonstrated the antineoplastic activities of aspirin in H. pylori‐related gastric carcinogenesis. 相似文献
79.
Lee SW Bonnah RA Higashi DL Atkinson JP Milgram SL So M 《The Journal of cell biology》2002,156(6):951-957
The Neisseria type IV pilus promotes bacterial adhesion to host cells. The pilus binds CD46, a complement-regulatory glycoprotein present on nucleated human cells (Källström et al., 1997). CD46 mutants with truncated cytoplasmic tails fail to support bacterial adhesion (Källström et al., 2001), suggesting that this region of the molecule also plays an important role in infection. Here, we report that infection of human epithelial cells by piliated Neisseria gonorrhoeae (GC) leads to rapid tyrosine phosphorylation of CD46. Studies with wild-type and mutant tail fusion constructs demonstrate that Src kinase phosphorylates tyrosine 354 in the Cyt2 isoform of the CD46 cytoplasmic tail. Consistent with these findings, infection studies show that PP2, a specific Src family kinase inhibitor, but not PP3, an inactive variant of this drug, reduces the ability of epithelial cells to support bacterial adhesion. Several lines of evidence point to the role of c-Yes, a member of the Src family of nonreceptor tyrosine kinases, in CD46 phosphorylation. GC infection causes c-Yes to aggregate in the host cell cortex beneath adherent bacteria, increases binding of c-Yes to CD46, and stimulates c-Yes kinase activity. Finally, c-Yes immunoprecipitated from epithelial cells is able to phosphorylate the wild-type Cyt2 tail but not the mutant derivative in which tyrosine 354 has been substituted with alanine. We conclude that GC infection leads to rapid tyrosine phosphorylation of the CD46 Cyt2 tail and that the Src kinase c-Yes is involved in this reaction. Together, the findings reported here and elsewhere strongly suggest that pilus binding to CD46 is not a simple static process. Rather, they support a model in which pilus interaction with CD46 promotes signaling cascades important for Neisseria infectivity. 相似文献
80.
Choi SS Kang BY Chung MJ Kim SD Park SH Kim JS Kang CY Ha NJ 《Journal of microbiology (Seoul, Korea)》2005,43(6):493-498
The safety assessment of Bifidobacterium longum SPM1205 isolated from healthy Koreans and this strain's inhibitory effects on fecal harmful enzymes of intestinal microflora were investigated. The overall safety of this strain was investigated during a feeding trial. Groups of SD rats were orally administered a test strain or commercial reference strain B. longum 1 x 10(9) CFU/kg body weight/day for four weeks. Throughout this time, their feed intake, water intake and live body weight were monitored. Fecal samples were periodically collected to test harmful enzyme activities of intestinal microflora. At the end of the four-week observation period, samples of blood, liver, spleen, kidney, and gut tissues were collected to determine for hematological parameters and histological differences. The results obtained in this experiment demonstrated that four weeks of consumption of this Bifidobacterium strain had no adverse effects on rat's general health status, blood biochemical parameters or histology. Therefore, it is likely to be safe for human use. Fecal harmful enzymes such as beta-glucosidase, beta-glucuronidase, tryptophanase and urease, were effectively inhibited during the administration of the B. longum SPM1205. These results suggested that this B. longum SPM 1205 could be used for humans as a probiotic strain. 相似文献