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1.
Atypical surface behavior of ceramides with nonhydroxy and 2-hydroxy very long-chain (C28–C32) PUFAs
Daniel A. Peñalva Gerardo M. Oresti Fernando Dupuy Silvia S. Antollini Bruno Maggio Marta I. Aveldaño María L. Fanani 《生物化学与生物物理学报:生物膜》2014
Unique species of ceramide (Cer) with very-long-chain polyunsaturated fatty acid (VLCPUFA), mainly 28–32 carbon atoms, 4–5 double bonds, in nonhydroxy and 2-hydroxy forms (n-V Cer and h-V Cer, respectively), are generated in rat spermatozoa from the corresponding sphingomyelins during the acrosomal reaction. The aim of this study was to determine the properties of these sperm-distinctive ceramides in Langmuir monolayers. Individual Cer species were isolated by HPLC and subjected to analysis of surface pressure, surface potential, and Brewster angle microscopy (BAM) as a function of molecular packing. In comparison with known species of Cer, n-V Cer and h-V Cer species showed much larger mean molecular areas and increased molecular dipole moments in liquid expanded phases, which suggest bending and partial hydration of the double bonded portion of the VLCPUFA. The presence of the 2-hydoxyl group induced a closer molecular packing in h-V Cer than in their chain-matched n-V Cer. In addition, all these Cer species showed liquid-expanded to liquid-condensed transitions at room temperature. Existence of domain segregation was confirmed by BAM. Additionally, thermodynamic analysis suggests a phase transition close to the physiological temperature for VLCPUFA-Cers if organized as bulk dispersions. 相似文献
2.
We recently published two papers detailing the structures of fluid phase phosphatidylglycerol (PG) lipid bilayers (Ku?erka et al., 2012 J. Phys. Chem. B 116: 232–239; Pan et al., 2012 Biochim. Biophys. Acta Biomembr. 1818: 2135–2148), which were determined using the scattering density profile model. This hybrid experimental/computational technique utilizes molecular dynamics simulations to parse a lipid bilayer into components whose volume probabilities follow simple analytical functional forms. Given the appropriate scattering densities, these volume probabilities are then translated into neutron scattering length density (NSLD) and electron density (ED) profiles, which are used to jointly refine experimentally obtained small angle neutron and X-ray scattering data. However, accurate NSLD and ED profiles can only be obtained if the bilayer's chemical composition is known. Specifically, in the case of neutron scattering, the lipid's exchangeable hydrogens with aqueous D2O must be accounted for, as they can have a measureable effect on the resultant lipid bilayer structures. This was not done in our above-mentioned papers. Here we report on the molecular structures of PG lipid bilayers by appropriately taking into account the exchangeable hydrogens. Analysis indicates that the temperature-averaged PG lipid areas decrease by 1.5 to 3.8 Å2, depending on the lipid's acyl chain length and unsaturation, compared to PG areas when hydrogen exchange was not taken into account. 相似文献
3.
目的:研究去甲基化药物5-氮杂胞嘧啶核苷(5-Azacytidine,5-Aza-C)对鼻咽癌细胞端粒长度及细胞生长增殖的影响。方法:
常规培养鼻咽癌CNE,CNE1,CNE2 及5-8F细胞系,5-Aza-C 处理鼻咽癌细胞后,甲基化测序聚合酶链反应(MSP)法检测亚端粒
区D4Z4 甲基化,端粒限制性片断检测端粒长度,CCK-8 检测细胞增殖。结果:2.5 uM浓度的5-Aza-C处理后,亚端粒区D4Z4 序
列的甲基化水平明显下降,约在15-20%之间,与处理前的甲基化水平(35-48%)有明显差异,差异均有统计学意义(P < 0.05)。在1
uM和2.5 uM浓度的5-Aza-C 处理后,四种细胞的端粒长度明显缩短,长度在2-4.5kb 之间,差异具有统计学意义(P < 0.05)。5uM
的5-Aza-C处理72 h 后,CNE,CNE1,CNE2 和5-8F 的生存率分别为51.27%,50.46%,48.85%,48.83%,10 uM 的5-azaC 处理72
h 后,CNE,CNE1,CNE2 和5-8F的生存率分别为31.64%,32.34%,30.01%,32.10%,与对照组比较差异有统计学意义(P<0.01)。结
论:5-Aza-C 能缩短端粒长度,抑制鼻咽癌细胞生长增殖活性。 相似文献
4.
Fecundity patterns of S and L type rotifers Brachionus plicatilis, which were previously found to have distinct growth ability, were analyzed using data of age-specific fecundity. The data were obtained by individual cultures of S and L type strains at 17, 24 and 34 °C. The pattern was analyzed by using normal probability functions. When the age was transformed into logarithmic value, the S and L types had an identical pattern of fecundity at every temperature. This fact indicates that the difference of the growth response to the temperature between S and L type strains stemmed only from the differences in net reproduction rate, not from the pattern. 相似文献
5.
6.
Evolutionary analysis of the picornavirus family 总被引:1,自引:0,他引:1
An exhaustive evolutionary analysis of the picornavirus family has been carried out using the amino acid sequences of several proteins of the viruses including: the capsid proteins (1D, 1B, and 1C) situated at the 5 end of the genome and responsible for the serotype of the viruses, and the viral polymerase (3D), located at the 3 end of the genome. The evolutionary relationships found among the viruses studied support the new classification, recently suggested, in contrast to the classical one, and the existence of a new genus for the picornavirus family. In the new taxonomic organization, five genera form the picornavirus family: (1) aphthoviruses, (2) cardioviruses, (3) hepatoviruses (previously classified as enteroviruses), (4) renteroviruses (which mainly constitute a combination of the previous genera rhinovirus and enterovirus), and (5) a new genus, with a new and unique representative: the echovirus 22. Our analysis also allowed us, for the first time, to propose the most probable sequence of speciation events to have given rise to the current picornavirus family.The bootstrap procedure was used to check the reliability of the phylogenetic trees obtained. The application of the method of the statistical geometry in distance space to internal branches of the tree revealed a high degree of evolutionary noise, which makes the resolution of some internal branching points difficult.
Correspondence to: J. Dopazo 相似文献
7.
R. D. Herbert J. Crosbie 《European journal of applied physiology and occupational physiology》1997,76(5):472-479
The first aim of this study was to measure the contributions of muscle and tendon to the total compliance of resting muscle-tendon
units. A second aim was to determine whether the decrease in muscle-tendon unit rest length produced by prolonged immobilisation
in a shortened position is mediated primarily by adaptations of the muscle or tendon. One ankle joint from each of five rabbits
was immobilised in a plantarflexed position for 14 days. The passive length-tension properties of soleus muscle fascicles
and tendons from both hindlimbs were measured using a video-based tensile-testing system. In non-immobilised muscles, muscle
fascicle strains exceeded tendon strains by up to four times. However, because the rest length of tendon was much greater
than that of muscle fascicles, changes in tendon length accounted for nearly half of the total change in muscle-tendon unit
length. The rest length of immobilised muscle-tendon units was less than that of non-immobilised muscle-tendon units from
contralateral limbs. Most of this difference was attributable to a change in the rest length of the tendon; there was little
change in the rest length of muscle fascicles. It is concluded that the tendon is responsible for a large part of the compliance
of rabbit soleus muscle-tendon units at physiological resting tensions, and that adaptation of tendon rest length is the primary
mechanism by which the rabbit soleus shortens in response to immobilisation at short lengths.
Accepted: 7 May 1997 相似文献
8.
9.
Selection on outlier loci and their association with adaptive phenotypes in Littorina saxatilis contact zones 下载免费PDF全文
A fundamental issue in speciation research is to evaluate phenotypic variation and the genomics driving the evolution of reproductive isolation between sister taxa. Above all, hybrid zones are excellent study systems for researchers to examine the association of genetic differentiation, phenotypic variation and the strength of selection. We investigated two contact zones in the marine gastropod Littorina saxatilis and utilized landmark‐based geometric morphometric analysis together with amplified fragment length polymorphism (AFLP) markers to assess phenotypic and genomic divergence between ecotypes under divergent selection. From genetic markers, we calculated the cline width, linkage disequilibrium and the average effective selection on a locus. Additionally, we conducted an association analysis linking the outlier loci and phenotypic variation between ecotypes and show that a proportion of outlier loci are associated with key adaptive phenotypic traits. 相似文献
10.