Comparison of redox and ligand binding behaviour of yeast and bovine cytochrome c oxidases using FTIR spectroscopy

Redox and CO photolysis FTIR spectra of yeast cytochrome c oxidase WT and mutants are compared to those from bovine and P. denitrificans CcOs in order to establish common functional features. All display changes that can be assigned to their E242 (bovine numbering) equivalent and to weakly H-bonded water molecules. The additional redox-sensitive band reported at 1736?cm^?1 in bovine CcO and previously assigned to D51 is absent from yeast CcO and couldn't be restored by introduction of a D residue at the equivalent position of the yeast protein. Redox spectra of yeast CcO also show much smaller changes in the amide I region, which may relate to structural differences in the region around D51 and the subunit I/II interface.     

Local cryostimulation acutely preserves maximum isometric handgrip strength following fatigue in young women

Several types of cryostimulation have been recently proposed to rapidly lower skin temperature therefore gaining a possible neuro/muscular recovery after strenuous exercise or, more generally, in sports. Local cryostimulation may be a viable and relatively portable tool to obtain physiological benefits in previously-efforted muscular districts. However, cohesive and standardized cryo-exposure protocols are lacking as well as the righteous procedure to efficaciously combine duration, treatments and temperature in relation to desirable effects on muscular strength. In this randomized-controlled study, fifty young women were tested for maximum isometric handgrip strength, before and after exhausting contractions.Following the fatiguing protocol, the intervention group (cryo, n = 25, 24.7 ± 2.5 years, BMI 21.7 ± 1.8 kg/m²) underwent a 6-min local cryostimulation (−160 °C) on the extensor-flexor muscles of the dominant arm, while control-matched peers sat rested in a thermo-neutral room (22 ± 0.5 °C). Handgrip tests were repeated at baseline (T0), after cryostimulation (T1), and 15 min after T1 (T2). Throughout the protocol, the AUC of the strength performance was significantly higher in the cryo- compared to control group (P = 0.006). In particular, following fatigue and cryostimulation, the cryo group preserved higher strength at T1 with respect to controls (26.8 ± 2.8 vs 23.9 ± 2.8 kg, Bonferroni's post-hoc, P < 0.01). Likewise, ventral and dorsal temperature, recorded with a thermal camera, were lower in cryo- than control group (P < 0.0001).In conclusion, a brief session of local cryostimulation may acutely preserve maximal isometric force in young women following a fatiguing protocol. These findings may have implications in orchestrating strategies of district muscular recovery.     

Physical and catalytic properties of a peroxidase derived from cytochrome c

Except for its redox properties, cytochrome c is an inert protein. However, dissociation of the bond between methionine-80 and the heme iron converts the cytochrome into a peroxidase. Dissociation is accomplished by subjecting the cytochrome to various conditions, including proteolysis and hydrogen peroxide (H₂O₂)-mediated oxidation. In affected cells of various neurological diseases, including Parkinson's disease, cytochrome c is released from the mitochondrial membrane and enters the cytosol. In the cytosol cytochrome c is exposed to cellular proteases and to H₂O₂ produced by dysfunctional mitochondria and activated microglial cells. These could promote the formation of the peroxidase form of cytochrome c. In this study we investigated the catalytic and cytolytic properties of the peroxidase form of cytochrome c. These properties are qualitatively similar to those of other heme-containing peroxidases. Dopamine as well as sulfhydryl group-containing metabolites, including reduced glutathione and coenzyme A, are readily oxidized in the presence of H₂O₂. This peroxidase also has cytolytic properties similar to myeloperoxidase, lactoperoxidase, and horseradish peroxidase. Cytolysis is inhibited by various reducing agents, including dopamine. Our data show that the peroxidase form of cytochrome c has catalytic and cytolytic properties that could account for at least some of the damage that leads to neuronal death in the parkinsonian brain.     

SECRETION OF LIPASES IN THE DIGESTIVE TRACT OF THE CRICKET Gryllus bimaculatus

Little is known concerning the sites and the ratios of the lipase secretions in insects, therefore we undertook an examination of the lipase secretion of fed and unfed adult female Gryllus bimaculatus. The ratio of triacylglyceride lipase, diacylglyceride lipase, and phosphatidylcholine lipase secreted by fed females in the caecum and ventriculus is 1:1.4:0.4. These activities decrease in the caecum by 30–40% in unfed females. The total lipase activity (TLA) in the caecum is about 10 times that in the ventriculus. Minimal lipase secretion occurs before and during the final moult, and remains at this level in unfed crickets, indicating a basal secretion rate. In 2‐day‐old fed females, about 10% of the TLA in the entire gut is found in the crop, about 70% in the caecum, 20% in the ventriculus, and 3% in the ileum. Lipases in the ventriculus are recycled back to the caecum and little is lost in the feces. Oleic acid stimulated in vitro lipase secretion, but lipids did not. Feeding stimulated lipase secretion, starvation reduced lipase secretion, but this does not prove a direct prandal regulation of secretion, because feeding also induced a size and volume increase of the caecum.     

Higher-Order Thalamocortical Inputs Gate Synaptic Long-Term Potentiation via Disinhibition

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无乳链球菌鱼源株10 kb基因序列对细菌致病力的影响

【目的】在前期比较基因组学分析中,我们发现中国无乳链球菌鱼源株GD201008-001基因组中有一段10 kb基因序列,内含11个未知功能的开放阅读框。为了研究该段基因序列与细菌的致病力的关系,本研究将这段基因进行了全段缺失。【方法】运用链球菌-大肠杆菌穿梭质粒p SET4s,构建了10 kb基因缺失株(Δ10 kb),并通过生物学性状的比较,细胞粘附试验,斑马鱼攻毒试验和缺失前后毒力相关基因转录水平的检测,评价该序列对无乳链球菌毒力的影响。【结果】经测序证明缺失株Δ10 kb构建成功,与亲本株GD201008-001相比较,缺失株Δ10 kb在细菌染色形态、对HEp-2细胞的粘附能力无明显差异,但在培养液中的生长速度略慢;缺失株Δ10 kb对斑马鱼的毒力明显增强,LD_(50)有极其显著的差异(P0.001);编码菌毛骨架蛋白2b的基因(PI-2b)和唾液酸酶基因(neul)在缺失株中的转录水平明显上升。【结论】该序列对无乳链球菌GD201008-001的毒力有显著的影响,可能调控某些毒力基因的转录表达,使细菌的毒力减弱。     

Inositol 1,4,5-trisphosphate receptor-isoform diversity in cell death and survival

Cell-death and -survival decisions are critically controlled by intracellular Ca^2 + homeostasis and dynamics at the level of the endoplasmic reticulum (ER). Inositol 1,4,5-trisphosphate (IP₃) receptors (IP₃Rs) play a pivotal role in these processes by mediating Ca^2 + flux from the ER into the cytosol and mitochondria. Hence, it is clear that many pro-survival and pro-death signaling pathways and proteins affect Ca^2 + signaling by directly targeting IP₃R channels, which can happen in an IP₃R-isoform-dependent manner. In this review, we will focus on how the different IP₃R isoforms (IP₃R1, IP₃R2 and IP₃R3) control cell death and survival. First, we will present an overview of the isoform-specific regulation of IP₃Rs by cellular factors like IP₃, Ca^2 +, Ca^2 +-binding proteins, adenosine triphosphate (ATP), thiol modification, phosphorylation and interacting proteins, and of IP₃R-isoform specific expression patterns. Second, we will discuss the role of the ER as a Ca^2 + store in cell death and survival and how IP₃Rs and pro-survival/pro-death proteins can modulate the basal ER Ca^2 + leak. Third, we will review the regulation of the Ca^2 +-flux properties of the IP₃R isoforms by the ER-resident and by the cytoplasmic proteins involved in cell death and survival as well as by redox regulation. Hence, we aim to highlight the specific roles of the various IP₃R isoforms in cell-death and -survival signaling. This article is part of a Special Issue entitled: Calcium signaling in health and disease. Guest Editors: Geert Bultynck, Jacques Haiech, Claus W. Heizmann, Joachim Krebs, and Marc Moreau.     

黄土高原雨水集聚深层入渗(RWCI)系统下山地果园土壤水分时空变异特征

水资源短缺是影响黄土高原雨养农业发展的关键性因素,雨水资源开发是缓解该地区水资源短缺的有效措施.本研究利用管式 TDR 系统监测21年红富士老果园0～300 cm土层土壤含水率变化,分析了雨水集聚深层入渗(RWCI)系统下黄土高原旱作山地果园土壤水分时空分布特征.结果表明: RWCI系统能够显著增加果园土壤含水率,特别是40～80 cm土层(土壤含水率低值区)土壤含水率,在该区域,不同设计深度(40、60和80 cm)RWCI处理(RWCI₄₀、RWCI₆₀和RWCI₈₀)年均土壤含水率分别较鱼鳞坑(CK)处理提高75.3%、85.4%和62.4%,分别较裸露坡地(BS)处理提高39.2%、47.2%和29.1%.RWCI₄₀、RWCI₆₀和RWCI₈₀处理土壤水分入渗最大深度分别为80、120和180 cm,显著深于CK处理(60 cm),其中土壤水分变化幅度最大的土层分别主要发生在0～60、0～100和0～120 cm.在果树整个生育期内,RWCI处理土壤平均含水率(0～300 cm)以RWCI₈₀处理最大,其次是RWCI₄₀和RWCI₆₀处理.总体来看,RWCI系统是黄土高原实现雨水资源化和农业高效用水的有效措施.     

Insights into the function of PsbR protein in Arabidopsis thaliana

The functional state of the Photosystem (PS) II complex in Arabidopsis psbR T-DNA insertion mutant was studied. The ΔPsbR thylakoids showed about 34% less oxygen evolution than WT, which correlates with the amounts of PSII estimated from Y_D^ox radical EPR signal. The increased time constant of the slow phase of flash fluorescence (FF)-relaxation and upshift in the peak position of the main TL-bands, both in the presence and in the absence of DCMU, confirmed that the S₂Q_A⁻ and S₂Q_B⁻ charge recombinations were stabilized in ΔPsbR thylakoids. Furthermore, the higher amount of dark oxidized Cyt-b559 and the increased proportion of fluorescence, which did not decay during the 100s time span of the measurement thus indicating higher amount of Y_D⁺Q_A⁻ recombination, pointed to the donor side modifications in ΔPsbR. EPR measurements revealed that S₁-to-S₂-transition and S₂-state multiline signal were not affected by mutation. The fast phase of the FF-relaxation in the absence of DCMU was significantly slowed down with concomitant decrease in the relative amplitude of this phase, indicating a modification in Q_A to Q_B electron transfer in ΔPsbR thylakoids. It is concluded that the lack of the PsbR protein modifies both the donor and the acceptor side of the PSII complex.     

Effect of lumbar fasciae on the stability of the lower lumbar spine

The biomechanical effect of tensioning the lumbar fasciae (LF) on the stability of the spine during sagittal plane motion was analysed using a validated finite element model of the normal lumbosacral spine (L4-S1). To apply the tension in the LF along the direction of the fibres, a local coordinate was allocated using dummy rigid beam elements that originated from the spinous process. Up to 10 Nm of flexion and 7.5 Nm of extension moment was applied with and without 20 N of lateral tension in the LF. A follower load of 400 N was additionally applied along the curvature of the spine. To identify how the magnitude of LF tension related to the stability of the spine, the tensioning on the fasciae was increased up to 40 N with an interval of 10 N under 7.5 Nm of flexion/extension moment. A fascial tension of 20 N produced a 59% decrease in angular motion at 2.5 Nm of flexion moment while there was a 12.3% decrease at 10 Nm in the L5-S1 segment. Its decrement was 53 and 9.6% at 2.5 Nm and 10 Nm, respectively, in the L4-L5 segment. Anterior translation was reduced by 12.1 and 39.0% at the L4-L5 and L5-S1 segments under 10 Nm of flexion moment, respectively. The flexion stiffness shows an almost linear increment with the increase in fascial tension. The results of this study showed that the effect of the LF on the stability of the spine is significant.