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81.
Givetian subaqueous density-flow deposits reveal the existence of a peritidal carbonate platform in sedimentary basins preserved within the Rabat-Tiflet-Zone of Morocco. The calcareous component assemblage displays a photozoan carbonate production mode of the neritic source environments. Characteristic elements of the allochthonous faunal association are colonial tabulate corals, stromatoporoids, crinoids, bryozoans and thick-shelled brachiopods. Active growing reefs and cortoid sand shoals at the platform margin as well as periplatform carbonates at the uppermost slope settings contributed bioclastic and lithoclastic lime debris to the toe-of-slope of the carbonate apron. Bipartite cobble rudstone beds are interpreted as deposits of hyperconcentrated density flows, which cannot be maintained on very low-angle slopes for as long as more dilute flows and represent short run-out distances. Beds consisting of mostly well-organized pebbly grainstones, packstones and grainstone-wackestone couplets are deposits of surge-like concentrated flows and turbidity flows. 相似文献
82.
An efficient, simple, and small-scale procedure for isolating functional ribonucleic acid (RNA) was successfully applied to
many different tissues of grape and apple. These woody plants are rich in polyphenolic compounds and polysaccharides that
could impair the RNA extraction. The method chosen is based on the use of hot borate buffer at alkaline pH supplemented with
several adjuvants and followed by selective precipitations. Starting with only 0.4 g of fresh tissue and working with small
tubes (2 mL), we were able to obtain good yields of high-quality RNA suitable for further applications. The procedure can
be proposed for many applications, and it is particularly highly recommended when isolating RNA from a large number of samples. 相似文献
83.
Sayli BS 《Biological trace element research》2001,81(3):255-267
As a part of a work to reveal the health effects of boron and its compounds, fertility and infertility states of sibs of probands,
contacted and interviewed in the field, and of their spouses were given. The purposes were to prevent duplications seemingly
inevitable in a relatively small community with prevailing consanguinity while analyzing marriages over respective generations
and to reveal if there occurred an aggregation of infertile couples. Any family without offspring after about the second year
of marriage was considered primary infertile as adopted throughout the study and such families were ascertained through the
individual pedigree charts set up according to the instructions of the proband, he (she) himself (herself) being excluded.
The rates of childless families of this type were 0.0–3.4% among male and 0.9–3.8% among female sibs of the participant, and
2.3–10.0% among male and 0.0–5.6% among female sibs of his (her) spouse with averages of 2.3% of 1589, 2.6% of 1589, 4.0%
of 1314, and 3.3% of 1436 instances, respectively. The differences were insignificant and the rates were not different from
those concerning probands themselves and that of a comparable segment of the Turkish population.
“Borate families/kindreds” with two or more members engaged in the borate industry were also assessed in order to detect if
there was a significant clustering of infertiles within the kindred. Although it was difficult to compare with a matched group,
few couples were examples of familial concentration of infertility. These results provided further support that boron exposure
does not affect human reproduction primarily and most probably secondarily.
This work was partly presented to the 10th International Symposium on Trace Elements in Man and in Animal (TEMA-10), Evian,
France, May 2–7, 1999. 相似文献
84.
85.
Marta Martínez-Bonet M. Ángeles Muñoz-Fernández Susana Álvarez 《Journal of cellular physiology》2019,234(5):5880-5887
Since the success of combined antiretroviral therapy, HIV-1-infected individuals are now living much longer. This increased life expectancy is accompanied by a higher prevalence of HIV-1 associated neurocognitive disorders. Rising too is the incidence in these patients of pathological hallmarks of Alzheimer's disease such as increased deposition of amyloid beta protein (Aβ). Although neurons are major sources of Aβ in the brain, astrocytes are the most numerous glial cells, therefore, even a small level of astrocytic Aβ metabolism could make a significant contribution to brain pathology. Neprilysin (NEP) is a decisive/crucial regulator of Aβ levels. We evaluated the effects of HIV-1 on Aβ deposition and the expression and activity of NEP in primary human astrocytes. Specifically, no differences in intracellular amyloid deposits were found between infected and control cells. However, primary cultures of infected astrocytes showed more extracellular Aβ levels compared to controls. This was accompanied by reduced expression of NEP and to a significant decrease in its activity. These results indicate that the presence of HIV-1 in the brain could contribute to the increase in the total burden of cerebral Aβ. 相似文献
86.
87.
William Miller III 《Ichnos》2013,20(4):305-312
Recently rediscovered type material referred to Muensteria Stern‐berg confirms that in its original (paleobotanical) definition this genus is too heterogenous to be useful in ichnotaxonomy. It contains plant remains, a coprolite string, and trace fossils. Some corrections concerning appearance of the analyzed specimens are introduced. 相似文献
88.
A novel blue‐emitting phosphor, Eu2+‐doping Al4B2O9, was prepared via a modified solid‐state reaction. Al4B2O9:Eu2+ nanoparticles with diameters varying in a range from 20 to 50 nm were obtained using urea as an auxiliary reagent at the optimum temperature of 850°C. The crystallization and particle sizes of Al4B2O9:Eu2+ were investigated using powder X‐ray diffraction (XRD) and transmission electron microscopy (TEM). Photoluminescence (PL) results showed that Al4B2O9:Eu2+ phosphor could be efficiently excited by the ultraviolet region from 240 to 410 nm, exhibiting bright blue emission. Further investigation on concentration‐dependent emission spectra indicated that the Al3.997B2O9:Eu2+0.003 phosphor exhibited the strongest luminescent, and the relative PL intensity decreased with increasing Eu2+ concentration due to concentration quenching. In addition, the concentration quenching for the one‐Eu‐site emission centers was caused by the electric multipole–multipole interaction. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
89.
《Bioscience, biotechnology, and biochemistry》2013,77(11):1944-1945
When screening for inhibitors of endothelin-converting enzyme (ECE), we isolated and identified Aspergillomarasmine A and B (AM-A and B) as potent inhibitors of ECE from the culture broth of Paecilomyces sp. N877. Both AM-A and AM-B had apparent activity in an in vivo experiment with big ET-1 induced sudden death, although the inhibitory activities of these compounds would be mainly due to the chelating effect. 相似文献
90.
Salvatore IncontroJorge Ramírez-Franco José Sánchez-PrietoMagdalena Torres 《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》2011,1813(1):14-26
The physiological responses of AMPA receptors can be modulated through the differential expression of their subunits and by modifying their number at the cell surface. Here we have studied the expression of AMPA receptor subunits (GluR1-4) mRNAs in cerebellar granule cells grown in depolarizing (25 mM K+) medium, and we have evaluated the effect of decreasing the [K+] in the culture medium for 24 h on both GluR1-4 expression (both mRNA and protein) and their presence at the plasma membrane. The expression of the four AMPAR subunits increases as the [K+] decreases, although the increase in GluR2 and GluR3 was only observed in the cell soma but not in the dendrites. Calcium entry through L-type calcium channel and CaMKIV activation are responsible for the reduction in the expression of AMPA receptor subunits in cells cultured in depolarizing conditions. Indeed, prolonged reduction of extracellular [K+] or blockage of L-type calcium channels enhanced both the surface insertion of the four AMPAR subunits and the AMPA response measured through intracellular calcium increase. These findings reveal a balanced increase in functional AMPA receptors at the surface of cells that can trigger strong increases in calcium in response to the persistent reduction of calcium entry. 相似文献