983 resultados para 149-898


Relevância:

20.00% 20.00%

Publicador:

Resumo:

The proton-rich isotope Sm-133 was produced via the fusion evaporation reaction Ca-40 + Ru-96. Its beta-delayed proton decay was studied by p-gamma coincidence in combination with a He-jet tape transport system, and half-lives, proton energy spectra, gamma-transitions following the proton emission, as well as beta-delayed proton branching ratios to the low-lying states in the grand-daughter nucleus were determined. Comparing the observed beta-delayed proton branching ratios with statistical model calculations, the best agreement is found assuming that only one level with the spin of 3/2 in Sm-133 decays or two levels with the spins of 1/2 and 5/2 decay with similar half-lives. The configuration-constrained nuclear potential energy surfaces of Sm-133 were calculated using the Woods-Saxon-Strutinsky method, which suggests a 1/2-ground state and a 5/2(+) isomer with an excitation energy of 120 keV. Therefore, the simple(EC+beta(+)) decay scheme of Sm-133 in Eur. Phys. J.A 11,277(2001) has been revised. In addition, our previous experimental data on the beta-delayed proton decay of Yb-149 reported in Eur. Phys. J. A 12,1 ( 2 0 0 1) was also analyzed using the same method. The spin-parity of Yb-149 is suggested to be 1/2(-).

Relevância:

20.00% 20.00%

Publicador:

Resumo:

关于无脊椎动物中是否存在细胞因子一直都存在着异议。从细胞因子本身入手,运用细胞生物学和免疫学手段,已经在软体动物、节肢动物和棘皮动物等无脊椎动物中证实了高等动物细胞因子样活性物质的存在,然而利用分子生物学手段至今没有得到任何核苷酸或蛋白序列信息,而从与细胞因子相关的分子如调控其表达的转录因子入手来研究无脊椎动物中的细胞因子样物质的存在,或许会得到意想不到的惊喜。 最近从人的单核细胞系THP-1中分离纯化出一种新型的转录因子,它可以被LPS诱导表达,产生的蛋白在TNF-α的表达过程中起着非常重要的作用,因而命名为LPS-induced TNF-α factor(LITAF)。随后该基因在小鼠和鸡中也被克隆分离出来,其编码的蛋白已经证实在TNF-α的表达过程中起着不可或缺的作用。迄今为止,在无脊椎动物中还没有相关同源基因的报道。 本研究采用大规模EST测序方法,结合锚定PCR技术从栉孔扇贝体内克隆到了高等动物LITAF基因的同源基因CfLITAF的全长cDNA序列。该cDNA全长为1240bp,其中5' 非编码区(UTR)为112 bp;开放阅读框(Open Reading Frame, ORF)包括450 bp,编码149个氨基酸残基,该多肽的理论分子量为16.08 kDa,等电点为6.77;3' UTR为678bp,包含一个poly A尾巴。SMART结构域预测发现CfLITAF蛋白含有一个保守的LITAF结构域。实时定量PCR检测CfLITAF基因在栉孔扇贝主要免疫器官中的表达分布情况,发现在所检测的六种组织血细胞、外套膜、肌肉、心、腮、性腺中均能检测到CfLITAF基因转录本的不同丰度的表达。血淋巴和肌肉中的表达量相差不大,而在心、外套膜、腮和性腺中的表达量要高于血淋巴和肌肉中的表达量,分别是血中表达量的2.45、2.82、9.23和24.93倍。 为了验证其表达量是否会受到LPS的诱导,利用QRT-PCR(quantitative real time PCR)检测了CfLITAF基因在受到LPS和PGN刺激后在血细胞中的表达规律。结果如下:在LPS刺激后3h,CfLITAF的表达量显著上调,达到了原初水平的1.5倍,随着时间的延长,其表达量逐渐恢复到刺激前水平;在用PGN刺激血细胞后的9个小时内均没有检测到CfLITAF基因mRNA表达量的显著变化。实验中所用血细胞为同一批原代培养的栉孔扇贝血淋巴细胞,细胞活力通过台盼蓝拒染实验测定。 CfLITAF基因的克隆与表达分析,不仅为进一步认识栉孔扇贝的免疫防御机制提供了实验参考,更重要的是为无脊椎动物中细胞因子样物质的研究提供了一个分子水平上的线索,为无脊椎动物中细胞因子样物质的研究奠定了理论基础。

Relevância:

20.00% 20.00%

Publicador:

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Brown sediment with organic matter present throughout. Clasts range from small to medium in size and angular to sub-rounded in shape. Lineations are common throughout the sample, with some grain stacking and minor amounts of rotation.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Brown sediment with clasts ranging from small to medium in size. Clast shape ranges from angular to rounded. Lineations and grain crushing are abundant throughout the sample. This sample also includes several inclusions of darker and fine grained domains. Comet structures can also be seen in some areas of the sample.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The action of a synthetic antimicrobial peptide analog of Plantaricin 149 (Pln149a) against Saccharomyces cerevisiae and its interaction with biomembrane model systems were investigated. Pln149a was shown to inhibit S. cerevisiae growth by more than 80% in YPD medium, causing morphological changes in the yeast wall and remaining active and resistant to the yeast proteases even after 24 h of incubation. Different membrane model systems and carbohydrates were employed to better describe the Pln149a interaction with cellular components using circular dichroism and fluorescence spectroscopies, adsorption kinetics and surface elasticity in Langmuir monolayers. These assays showed that Pln149a does not interact with either mono/polysaccharides or zwitterionic LUVs, but is strongly adsorbed to and incorporated into negatively charged surfaces, causing a conformational change in its secondary structure from random-coil to helix upon adsorption. From the concurrent analysis of Pln149a adsorption kinetics and dilatational surface elasticity data, we determined that 2.5 mu M is the critical concentration at which Pln149a will disrupt a negative DPPG monolayer. Furthermore, Pln149a exhibited a carpet-like mechanism of action, in which the peptide initially binds to the membrane, covering its surface and acquiring a helical structure that remains associated to the negatively charged phospholipids. After this electrostatic interaction, another peptide region causes a strain in the membrane, promoting its disruption. (C) 2009 Elsevier B.V. All rights reserved.