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91.
Hierarchical folding and reorganization of chromosomes are linked to transcriptional changes in cellular differentiation 下载免费PDF全文
Mariano Barbieri Benjamin L Moore Dorothee CA Kraemer Stuart Aitken Sheila Q Xie Kelly J Morris Masayoshi Itoh Hideya Kawaji Ines Jaeger Yoshihide Hayashizaki Piero Carninci Alistair RR Forrest The FANTOM Consortium Colin A Semple Josée Dostie Ana Pombo Mario Nicodemi 《Molecular systems biology》2015,11(12)
92.
The role of functional traits and trade-offs in structuring phytoplankton communities: scaling from cellular to ecosystem level 总被引:6,自引:0,他引:6
Trait-based approaches to community structure are increasingly used in terrestrial ecology. We show that such an approach, augmented by a mechanistic analysis of trade-offs among functional traits, can be successfully used to explain community composition of marine phytoplankton along environmental gradients. Our analysis of literature on major functional traits in phytoplankton, such as parameters of nutrient-dependent growth and uptake, reveals physiological trade-offs in species abilities to acquire and utilize resources. These trade-offs, arising from fundamental relations such as cellular scaling laws and enzyme kinetics, define contrasting ecological strategies of nutrient acquisition. Major groups of marine eukaryotic phytoplankton have adopted distinct strategies with associated traits. These diverse strategies of nutrient utilization can explain the distribution patterns of major functional groups and size classes along nutrient availability gradients. 相似文献
93.
Saman Rasoul Jan Paul Ottervanger Jan-Henk E Dambrink Menko-Jan de Boer Jan CA Hoorntje AT Marcel Gosselink Felix Zijlstra Harry Suryapranata Arnoud WJ van't Hof 《BMC cardiovascular disorders》2007,7(1):1-7
Background
We have previously documented significant differences in orthogonal P wave morphology between patients with and without paroxysmal atrial fibrillation (PAF). However, there exists little data concerning normal P wave morphology. This study was aimed at exploring orthogonal P wave morphology and its variations in healthy subjects.Methods
120 healthy volunteers were included, evenly distributed in decades from 20–80 years of age; 60 men (age 50+/-17) and 60 women (50+/-16). Six-minute long 12-lead ECG registrations were acquired and transformed into orthogonal leads. Using a previously described P wave triggered P wave signal averaging method we were able to compare similarities and differences in P wave morphologies.Results
Orthogonal P wave morphology in healthy individuals was predominately positive in Leads X and Y. In Lead Z, one third had negative morphology and two-thirds a biphasic one with a transition from negative to positive. The latter P wave morphology type was significantly more common after the age of 50 (P < 0.01). P wave duration (PWD) increased with age being slightly longer in subjects older than 50 (121+/-13 ms vs. 128+/-12 ms, P < 0.005). Minimal intraindividual variation of P wave morphology was observed.Conclusion
Changes of signal averaged orthogonal P wave morphology (biphasic signal in Lead Z), earlier reported in PAF patients, are common in healthy subjects and appear predominantly after the age of 50. Subtle age-related prolongation of PWD is unlikely to be sufficient as a sole explanation of this finding that is thought to represent interatrial conduction disturbances. To serve as future reference, P wave morphology parameters of the healthy subjects are provided. 相似文献94.
Hedley CA Emsley Craig J Smith Carole M Gavin Rachel F Georgiou Andy Vail Elisa M Barberan Karen Illingworth Sylvia Scarth Vijitha Wickramasinghe Margaret E Hoadley Nancy J Rothwell Pippa J Tyrrell Stephen J Hopkins 《BMC neurology》2007,7(1):1-12
Background
As critical mediators of local and systemic inflammatory responses, cytokines are produced in the brain following ischaemic stroke. Some have been detected in the circulation of stroke patients, but their role and source is unclear. Focusing primarily on interleukin(IL)-1-related mechanisms, we serially measured plasma inflammatory markers, and the production of cytokines by whole blood, from 36 patients recruited within 12 h and followed up to 1 year after acute ischaemic stroke (AIS).Results
Admission plasma IL-1 receptor antagonist (IL-1ra) concentration was elevated, relative to age-, sex-, and atherosclerosis-matched controls. IL-1β, soluble IL-1 receptor type II, tumour necrosis factor (TNF)-α, TNF-RII, IL-10 and leptin concentrations did not significantly differ from controls, but peak soluble TNF receptor type I (sTNF-RI) in the first week correlated strongly with computed tomography infarct volume at 5–7 days, mRS and BI at 3 and 12 months. Neopterin was raised in patients at 5–7 d, relative to controls, and in subjects with significant atherosclerosis. Spontaneous IL-1β, TNF-α and IL-6 gene and protein expression by blood cells was minimal, and induction of these cytokines by lipopolysaccharide (LPS) was significantly lower in patients than in controls during the first week. Minimum LPS-induced cytokine production correlated strongly with mRS and BI, and also with plasma cortisol.Conclusion
Absence of spontaneous whole blood gene activation or cytokine production suggests that peripheral blood cells are not the source of cytokines measured in plasma after AIS. Increased plasma IL-1ra within 12 h of AIS onset, the relationship between sTNF-RI and stroke severity, and suppressed cytokine induction suggests early activation of endogenous immunosuppressive mechanisms after AIS. 相似文献95.
Yuansha Chen Peter Bystricky Jacob Adeyeye Pinaki Panigrahi Afsar Ali Judith A Johnson CA Bush JG MorrisJr OC Stine 《BMC microbiology》2007,7(1):20
Background
In V. cholerae, the biogenesis of capsule polysaccharide is poorly understood. The elucidation of capsule structure and biogenesis is critical to understanding the evolution of surface polysaccharide and the internal relationship between the capsule and LPS in this species. V. cholerae serogroup O31 NRT36S, a human pathogen that produces a heat-stable enterotoxin (NAG-ST), is encapsulated. Here, we report the covalent structure and studies of the biogenesis of the capsule in V. cholerae NRT36S. 相似文献96.
Carl?Shooner Pierre-Luc?Caron Guylaine?Fréchette-Frigon Valérie?Leblanc Marie-Claude?Déry Eric?AsselinEmail author 《Reproductive biology and endocrinology : RB&E》2005,3(1):20
Background
During early rat pregnancy, trophoblast of the tiny embryo joins with the endometrium and epithelial cells undergo apoptosis. Near the end of pregnancy, regression of the decidua basalis (DB) is also observed (from day 14 to 20). However, little is known about the intra-cellular and molecular mechanisms involved in apoptosis regulation in the uterus during pregnancy. The objective of the present study was to investigate the presence and the developmental expression of transforming growth factor-beta isoforms (TGF-beta well known differentiation factor) in the rat endometrium throughout pregnancy and its action in vitro using cultured endometrial stromal cells. 相似文献97.
将化学合成的单链猪胰岛素前体(PIP)基因和用聚合酶链反应得到的α交配因子前导顺序(αMFL)基因插入质粒pVT102-U的醇脱氢酶基因ADH1的启动子和3’终止顺序之间而生成质粒pVT102-U/αMFL-PIP.被pVT102-U/αMFL-PIP转化的酵母(Saccharomyces cerevistae)可表达单链前体并分泌到培养基中.前体在纯化后可通过胰蛋白酶的转肽作用转变成人胰岛素.纯化的人胰岛素具有全部活力并可结晶.人胰岛素的总收率为每升培养液25mg. 相似文献
98.
The phylogenetic position of the Pedetidae, represented by a single species
Pedetes capensis, is controversial, reflecting in part the retention of
both Hystricomorphous and Sciurognathous characteristics in this rodent. In
an attempt to clarify the species evolutionary relationships, mtDNA gene
sequences from 10 rodent species (representing seven families) were
analyzed using phenetic, parsimony, and maximum-likelihood methods of
phylogenetic inference; the rabbit, Oryctolagus cuniculus (Order
Lagomorpha), and cow, Bos taurus (Order Artiodactyla), were used as
outgroups. Investigation of 714 base pairs of the protein-coding cytochrome
b gene indicate strong base bias at the third codon position with
significant rate heterogeneity evident between the three structural domains
of this gene. Similar analyses conducted on 816 base pairs of the 12S rRNA
gene revealed a transversion bias in the loop sections of all taxa. The
cytochrome b gene sequences proved useful in resolving associations between
closely related species but failed to produce consistent tree topologies at
the family level. In contrast, phylogenetic analysis of the 12S rRNA gene
resulted in strong support for the clustering of
Pedetidae/Heteromyidae/Geomyidae and Muridae in one clade to the exclusion
of the Hystricidae/Thryonomyidae and Sciuridae, a finding which is
concordant with studies of rodent fetal membranes as well as reproductive
and other anatomical features.
相似文献
99.
玉米叶片生长部位渗透调节和生长的生物物理参数变化 总被引:6,自引:0,他引:6
玉米叶片生长部位随着水分胁迫加剧ψ_w降低、LER减慢。LER从最大到零,快速干旱处理的ψw从-0.55降至-0.85 MPa;缓慢干旱处理ψ_w从-0.88降至-1.13 MPa。在任何一种LER下,缓慢干旱处理的ψ_s比快速干旱处理更低,生长停止时,前者为-1.57 MPa,而后者为-1.30MPa。缓慢干旱叶片尽管在更低ψ_w下,仍能维持一定膨压,保持一定的生长速率。经历长时间水分胁迫会改变细胞延伸生长的生物物理参数,增大临界膨压(0.08~0.09 MPa)。这是水分胁迫植株,在一定ψ_p下生长速率减慢的原因。 相似文献
100.
Principal component models for sparse functional data 总被引:5,自引:0,他引:5