排序方式: 共有31条查询结果,搜索用时 1 毫秒
1.
Characterization of cross-bridge elasticity and kinetics of cross-bridge cycling during force development in single smooth muscle cells 总被引:4,自引:2,他引:2
下载免费PDF全文
![点击此处可从《The Journal of general physiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Force development in smooth muscle, as in skeletal muscle, is believed to reflect recruitment of force-generating myosin cross-bridges. However, little is known about the events underlying cross-bridge recruitment as the muscle cell approaches peak isometric force and then enters a period of tension maintenance. In the present studies on single smooth muscle cells isolated from the toad (Bufo marinus) stomach muscularis, active muscle stiffness, calculated from the force response to small sinusoidal length changes (0.5% cell length, 250 Hz), was utilized to estimate the relative number of attached cross-bridges. By comparing stiffness during initial force development to stiffness during force redevelopment immediately after a quick release imposed at peak force, we propose that the instantaneous active stiffness of the cell reflects both a linearly elastic cross-bridge element having 1.5 times the compliance of the cross-bridge in frog skeletal muscle and a series elastic component having an exponential length-force relationship. At the onset of force development, the ratio of stiffness to force was 2.5 times greater than at peak isometric force. These data suggest that, upon activation, cross-bridges attach in at least two states (i.e., low-force-producing and high-force-producing) and redistribute to a steady state distribution at peak isometric force. The possibility that the cross-bridge cycling rate was modulated with time was also investigated by analyzing the time course of tension recovery to small, rapid step length changes (0.5% cell length in 2.5 ms) imposed during initial force development, at peak force, and after 15 s of tension maintenance. The rate of tension recovery slowed continuously throughout force development following activation and slowed further as force was maintained. Our results suggest that the kinetics of force production in smooth muscle may involve a redistribution of cross-bridge populations between two attached states and that the average cycling rate of these cross-bridges becomes slower with time during contraction. 相似文献
2.
Duarte CD Tributino JL Lacerda DI Martins MV Alexandre-Moreira MS Dutra F Bechara EJ De-Paula FS Goulart MO Ferreira J Calixto JB Nunes MP Bertho AL Miranda AL Barreiro EJ Fraga CA 《Bioorganic & medicinal chemistry》2007,15(6):2421-2433
We describe herein the discovery of LASSBio-881 (3c) as a novel in vivo antinociceptive, anti-inflammatory, and in vitro antiproliferative and antioxidant compound, with a cannabinoid ligand profile. We observed that LASSBio-881 (3c) was able to bind to CB1 receptors (71% at 100microM) and also to inhibit T-cell proliferation (66% at 10microM) probably by binding to CB2 receptors, in a non-proapoptotic manner, different from anandamide (1). It was also demonstrated that LASSBio-881 (3c) had an important antioxidant profile toward free radicals (DPPH and hydroxyl), probably due to its particular redox behavior, which reflects the presence of both nitro and 3,5-di-tert-butyl-4-hydroxyphenyl sub-units, as demonstrated by cyclic voltammetry studies. In addition, we showed that these structural sub-units are essential for the observed pharmacological activity. 相似文献
3.
Diana?Negr?o?Cavalcanti Meire-Anne?Rezende?de?Oliveira Joel?Campos?De-Paula Leandro?Silva?Barbosa Tamara?Fogel Marcelo?Alves?Pinto Izabel?Christina?Nunes?de?Palmer Paix?o Valéria?Laneuville?TeixeiraEmail author 《Journal of applied phycology》2011,23(5):873-876
This study evaluated the variability in the production of an HIV-1 antiviral diterpene in individuals of Dictyota menstrualis throughout reproductive stages. The brown alga Dictyota has an isomorphic biphasic life cycle. The quantification of the active principle by GC–FID indicated a greater production
of the diterpene in the female gametophytic phase (42.11 ppm). However, these individuals had the highest variation between
individuals (standard deviation of 68.20 ppm in the range from 0.39 to 227 ppm). Sporophytic individuals showed less variability.
This variability in the production of the antiviral diterpene is important to the development of future antiviral drugs. 相似文献
4.
Juliana Marzinek Orlando Cavalari De-Paula Denise Maria Trombert Oliveira 《Plant Systematics and Evolution》2010,285(1-2):127-130
Rib numbers have traditionally been used in identification keys of Eupatorieae. Some species, however, demonstrate variations in this character much greater than those registered in the literature, making the use of this trait controversial. The large variations seen among some species of Eupatorieae examined in this work were found to be related to the fact that rib number is more closely associated with the pressure exerted by neighboring flowers on the capitulum than with genetic factors. According to our results, ribs are not a reliable taxonomic character for broad use in Eupatorieae, being especially inappropriate for Chromolaena stachyophylla, Praxelis pauciflora, and Vittetia orbiculata. The association between the occurrence of vascular bundles and ribs is also discussed, and the variability seen in some Eupatorieae is analyzed. Our data indicate that the formation of the ribs on the cypselae is determined more by the position occupied by the flower on the inflorescence than by the occurrence of vascular bundles. 相似文献
5.
Jamil M Neto Marina GM Viturino Galina Ananina Flvia F Bajano Sueli M da S Costa Alicia B Roque Gessica FS Borges Raissa Franchi Priscila HH Rim Flvio M Medina Fernando F Costa Mnica B de Melo Jos PC de Vasconcellos 《Experimental biology and medicine (Maywood, N.J.)》2021,246(21):2290
This study aimed to investigate the association among genetic variants of the complement pathway CFB R32Q (rs641153), C3 R102G (rs2230199), and CFH (rs1410996) with age-related macular degeneration (AMD) in a sample of the Brazilian population. In a case-control study, 484 AMD patients were classified according to the clinical age-related maculopathy grading system (CARMS) and compared to 479 unrelated controls. The genetic variants rs1410996 of complement H (CFH), rs641153 of complement factor B (CFB), and rs2230199 of complement 3 (C3) were evaluated through polymerase chain reaction (PCR) and direct sequencing. The associations between single nucleotide polymorphisms (SNPs) and AMD, adjusted by age, were assessed by using logistic regression models. A statistically significant association was observed between AMD risk and rs2230199 variant with an OR of 2.01 (P = 0.0002) for CG individuals compared to CC individuals. Regarding the comparison of advanced AMD versus the control group, the OR was 2.12 (P = 0.0036) for GG versus AA genotypes for rs1410996 variant. Similarly, the OR for rs2230199 polymorphism was 2.3034 (P = 5.47e-05) when comparing CG individuals to CC carriers. In contrast, the rs641153 variant showed a significant protective effect against advanced AMD for GA versus GG genotype (OR = 0.4406; P = 0.0019). When comparing wet AMD versus controls, a significant association was detected for rs1410996 variant (OR = 2.16; P = 0.0039) comparing carriers of the homozygous GG versus AA genotype, as well as in the comparisons of GG (OR = 3.0713; P = 0.0046) and CG genotypes (OR = 2.2249; P = 0.0002) versus CC genotype for rs2230199 variant, respectively. The rs641153 variant granted a significant protective effect against wet AMD for GA versus GG genotypes (OR = 0.4601; P = 0.0044). Our study confirmed the risk association between rs2230199 and rs1410996 variants and AMD, and the protective role against AMD for rs641153 variant. 相似文献
6.
7.
Claudia T Guimaraes Christiano C Simoes Maria Marta Pastina Lyza G Maron Jurandir V Magalhaes Renato CC Vasconcellos Lauro JM Guimaraes Ubiraci GP Lana Carlos FS Tinoco Roberto W Noda Silvia N Jardim-Belicuas Leon V Kochian Vera MC Alves Sidney N Parentoni 《BMC genomics》2014,15(1)
Background
Aluminum (Al) toxicity is an important limitation to food security in tropical and subtropical regions. High Al saturation on acid soils limits root development, reducing water and nutrient uptake. In addition to naturally occurring acid soils, agricultural practices may decrease soil pH, leading to yield losses due to Al toxicity. Elucidating the genetic and molecular mechanisms underlying maize Al tolerance is expected to accelerate the development of Al-tolerant cultivars.Results
Five genomic regions were significantly associated with Al tolerance, using 54,455 SNP markers in a recombinant inbred line population derived from Cateto Al237. Candidate genes co-localized with Al tolerance QTLs were further investigated. Near-isogenic lines (NILs) developed for ZmMATE2 were as Al-sensitive as the recurrent line, indicating that this candidate gene was not responsible for the Al tolerance QTL on chromosome 5, qALT5. However, ZmNrat1, a maize homolog to OsNrat1, which encodes an Al3+ specific transporter previously implicated in rice Al tolerance, was mapped at ~40 Mbp from qALT5. We demonstrate for the first time that ZmNrat1 is preferentially expressed in maize root tips and is up-regulated by Al, similarly to OsNrat1 in rice, suggesting a role of this gene in maize Al tolerance. The strongest-effect QTL was mapped on chromosome 6 (qALT6), within a 0.5 Mbp region where three copies of the Al tolerance gene, ZmMATE1, were found in tandem configuration. qALT6 was shown to increase Al tolerance in maize; the qALT6-NILs carrying three copies of ZmMATE1 exhibited a two-fold increase in Al tolerance, and higher expression of ZmMATE1 compared to the Al sensitive recurrent parent. Interestingly, a new source of Al tolerance via ZmMATE1 was identified in a Brazilian elite line that showed high expression of ZmMATE1 but carries a single copy of ZmMATE1.Conclusions
High ZmMATE1 expression, controlled either by three copies of the target gene or by an unknown molecular mechanism, is responsible for Al tolerance mediated by qALT6. As Al tolerant alleles at qALT6 are rare in maize, marker-assisted introgression of this QTL is an important strategy to improve maize adaptation to acid soils worldwide.Electronic supplementary material
The online version of this article (doi:10.1186/1471-2164-15-153) contains supplementary material, which is available to authorized users. 相似文献8.
Background
Hyperplasia of usual type (HUT) is a common proliferative lesion associated with a slight elevated risk for subsequent development of breast cancer. Cell cycle-related proteins would be helpful to determine the putative role of these markers in the process of mammary carcinogenesis. The aim of this study was to analyze the expression of cell cycle related proteins in HUT of breast specimens of patients with and without breast cancer, and compare this expression with areas of invasive carcinomas. 相似文献9.
10.
Marina GM Viturino Jamil M Neto Flvia F Bajano Sueli MS Costa Alicia B Roque Gessica FS Borges Galina Ananina Priscila HH Rim Flvio M Medina Fernando F Costa Jos PC de Vasconcellos Mnica B de Melo 《Experimental biology and medicine (Maywood, N.J.)》2021,246(10):1148
This study aimed to evaluate the role of APOE polymorphisms (rs429358 and rs7412) in the risk of age-related macular degeneration in a sample of the Southeastern Brazilian population. Seven hundred and five unrelated individuals were analyzed, 334 with age-related macular degeneration (case group), and 371 without the disease (control group). In the case group, patients were further stratified according to disease phenotypes, divided into dry and wet age-related macular degeneration, and non-advanced and advanced age-related macular degeneration. APOE polymorphisms (rs429358 and rs7412) were evaluated through polymerase chain reaction and direct sequencing. In the comparison of cases vs. controls, none of the associations reached statistical significance, considering the Bonferroni-adjusted P-value, although there was a suggestive protection for the E3/E4 genotype (OR = 0.626; P-value = 0.037) and E4 carriers (OR = 0.6515; P-value = 0.047). Statistically significant protection for both the E3/E4 genotype and E4 carriers was observed in the comparisons: advanced age-related macular degeneration vs. controls (OR = 0.3665, P-value = 0.491 × 10−3 and OR = 0.4031, P-value = 0.814 × 10−3, respectively), advanced age-related macular degeneration vs. non-advanced age-related macular degeneration (OR = 0.2529, P-value = 0.659 × 10−4 and OR = 0.2692, P-value = 0.631 × 10−4, respectively). In the comparison of wet age-related macular degeneration vs. control, protection was statistically significant only for E3/E4 (OR = 0.4052, P-value = 0.001). None of the comparisons demonstrated any significant association for E2 genotypes or E2 carriers in age-related macular degeneration risk in this study. Findings suggest a protective role of the E4 haplotype in the APOE gene in the risk for advanced and wet forms of age-related macular degeneration, in a sample of the Brazilian population. To our knowledge, this is the first Brazilian study to show the association between APOE polymorphisms and age-related macular degeneration. 相似文献