Positive selection for elevated gene expression noise in yeast

It is well known that the expression noise is lessened by natural selection for genes that are important for cell growth or are sensitive to dosage. In theory, expression noise can also be elevated by natural selection when noisy gene expression is advantageous. Here we analyze yeast genome‐wide gene expression noise data and show that plasma‐membrane transporters show significantly elevated expression noise after controlling all confounding factors. We propose a model that explains why and under what conditions elevated expression noise may be beneficial and subject to positive selection. Our model predicts and the simulation confirms that, under certain conditions, expression noise also increases the evolvability of gene expression by promoting the fixation of favorable expression level‐altering mutations. Indeed, yeast genes with higher noise show greater between‐strain and between‐species divergences in expression, even when all confounding factors are excluded. Together, our theoretical model and empirical results suggest that, for yeast genes such as plasma‐membrane transporters, elevated expression noise is advantageous, is subject to positive selection, and is a facilitator of adaptive gene expression evolution.     

A proteomic approach to identify differentially expressed plasma proteins between the fed and prolonged fasted states

Prolonged fasting is characterized by consecutive phases, a short period of adaptation (phase 1), phase 2 (P2) characterized by fat oxidation, and phase 3 (P3) during which energy requirements are mostly derived from increased protein utilization. At this latter stage, food seeking behavior is induced. Very few circulating biomolecules have been identified that are involved in the response to prolonged fasting. To this end, rat plasma samples were compared by a proteomic approach, using 2‐DE. The results revealed a selective variation of the levels of apolipoprotein A‐IV, A‐I, and E, haptoglobin, transthyretin, plasma retinol binding‐protein, and vitamin D binding‐protein in P2 and P3. The variations in protein levels were confirmed by ELISA. Changes in mRNA levels encoding these proteins did not systematically correlate well with protein concentrations, and tissue‐specific regulation of mRNA expression was observed, underlining the complex metabolic regulation in response to food deprivation. In late fasting, the marked reduction of apolipoprotein A‐IV levels could contribute to the alarm signal that triggers refeeding. The variations of the other differentially expressed proteins are more likely related to lipid metabolism and insulin signaling alterations.     

Niemann–Pick C2 (NPC2) and intracellular cholesterol trafficking

Cholesterol is an important precursor for numerous biologically active molecules, and it plays a major role in membrane structure and function. Cholesterol can be endogenously synthesized or exogenously taken up via the endocytic vesicle system and subsequently delivered to post-endo/lysosomal sites including the plasma membrane and the endoplasmic reticulum. Niemann–Pick C (NPC) disease results in the accumulation of exogenously-derived cholesterol, as well as other lipids, in late endosomes and lysosomes (LE/LY). Identification of the two genes that underlie NPC disease, NPC1 and NPC2, has focused attention on the mechanisms by which lipids, in particular cholesterol, are transported out of the LE/LY compartment. This review discusses the role of the NPC2 protein in cholesterol transport, and the potential for concerted action of NPC1 and NPC2 in regulating normal intracellular cholesterol homeostasis.     

Intracellular localisation of PPI1 (proton pump interactor, isoform 1), a regulatory protein of the plasma membrane H+-ATPase of Arabidopsis thaliana

PPI1 (proton pump interactor isoform 1) is a novel protein able to interact with the C-terminal autoinhibitory domain of the Arabidopsis thaliana plasma membrane (PM) H⁺-ATPase. In vitro, PPI1 binds the PM H⁺-ATPase in a site different from the known 14-3-3 binding site and stimulates its activity. In this study, we analysed the intracellular localisation of PPI1. The intracellular distribution was monitored in A. thaliana cultured cells by immunolocalisation using an antiserum against the PPI1 N-terminus and in Vicia faba guard cells and epidermal cells by transient expression of a GFP::PPI1 fusion. The results indicate that the bulk of PPI1 is localised at the endoplasmic reticulum, from which it might be recruited to the PM for interaction with the H⁺-ATPase in response to as yet unidentified signals.     

低温氧等离子体杀灭铜绿假单胞菌的效果及机理

【目的】本文采用低温氧等离子体,在自行设计的远程等离子体反应装置中,对位于不同放电区域（放电区,余辉区,远程区）的模拟染菌载体聚对苯二甲酸乙二醇酯（PET）表面的铜绿假单胞菌(Pseudomonas aeruginosa)的杀灭效果和机理进行了研究。【方法】采用扫描电子显微镜观察了等离子体处理前后细菌细胞的形貌变化,采用考马斯亮蓝法测定了等离子体处理后细菌蛋白质泄漏量,采用双悬浮探针对氧等子体的电子温度和离子浓度以及电子自旋共振波谱对自由基浓度进行了测定。【结果】强放电区、余辉区和远程区处理30s后的灭菌效果分别为4.2 ,3.8和2.6;扫描电镜观察结果和蛋白泄漏量测定结果证明细菌细胞被损毁,在强放电区是电子、离子、自由基和紫外光子的协同作用,而在余辉区和远程区的灭杀作用主要因自由基所为。【结论】证明该反应装置可有效实现活性粒子的分离,在远程等离子体场中揭示了等离子体灭菌的规律和机理。     

Platelet-Rich Plasma: Support for Its Use in Wound Healing

Previous topical growth factor studies have shown that recombinant human platelet-derived growth factor-BB isomer (rhPDGF-BB) is an efficacious treatment of chronic diabetic foot ulceration. A newer treatment, autologous platelet-rich plasma (PRP), represents a greater similarity to the natural healing process as a composite of multiple growth factors, is safe due to its autologous nature, and is produced as needed from patient blood. A review of the literature shows few studies performed with scientific rigor, although the safety of PRP appears to be validated. As the use of PRP increases, additional studies may establish PRP as an efficacious treatment modality and guide future treatment of chronic diabetic foot ulceration.     

Erythrocytes serve as a reservoir for cellular and extracellular sphingosine 1‐phosphate

Sphingosine 1‐phosphate (S1P) in blood is phosphorylated, stored, and transported by red blood cells (RBC). Release of S1P from RBC into plasma is a regulated process that does not occur in plasma‐ or serum‐free media. Plasma fractionation and incubations with isolated and recombinant proteins identified high density lipoprotein (HDL) and serum albumin (SA) as non‐redundant endogenous triggers for S1P release from RBC. S1P bound to SA and HDL was able to stimulate the S1P₁ receptor in calcium flux experiments. The binding capability of acceptor molecules triggers S1P release, as demonstrated with the anti‐S1P antibody Sphingomab?. More S1P was extracted from RBC membranes by HDL than by SA. Blood samples from anemic patients confirmed a reduced capacity for S1P release in plasma. In co‐cultures of RBC and endothelial cells (EC), we observed transcellular transportation of S1P as a second function of RBC‐associated S1P in the absence of SA and HDL and during tight RBC‐EC contact, mimicking conditions in tissue interstitium and capillaries. In contrast to S1P bound to SA and HDL, RBC‐associated S1P was significantly incorporated by EC after S1P lyase (SGPL1) inhibition. RBC‐associated S1P, therefore, has two functions: (1) It contributes to the cellular pool of SGPL1‐sensitive S1P in tissues after transcellular transportation and (2) it helps maintain extracellular S1P levels via SA and HDL independently from SGPL1 activity. J. Cell. Biochem. 109: 1232–1243, 2010. © 2010 Wiley‐Liss, Inc.     

Influence of seminal plasma on fertility of fresh and frozen-thawed stallion epididymal spermatozoa

The use of epididymal stallion spermatozoa for routine artificial insemination can secure easy future use of valuable genetics after unforeseen death or injury of a valuable stallion.     

Lysozyme activities and immunoglobulin concentrations in seminal plasma and spermatozoa of different teleost species and indications on its significance for sperm function

The occurrence of lysozyme and immunoglobulin (Ig) in semen of different teleost species (brown trout—Salmo trutta, perch—Perca fluviatilis, burbot—Lota lota) was studied. In all investigated species lysozyme activities (1.13-1.45 U ml⁻¹) and Ig concentrations (T-Ig: 1.11-1.61 μg ml⁻¹, IgG [measured only in brown trout]: 1.49 μg ml⁻¹) were detected in seminal plasma. Ig was also found in spermatozoa (T-Ig: 0.234-0.357 μg/g protein, IgG: 0.198 μg ml⁻¹) while spermatozoal lysozyme activities were low and fluctuating (0.093-0.164 U/g protein). In Salmo trutta lysozyme activities and immunoglobulin levels were compared between semen samples with high and low sperm motility as motility is an indicator for sperm fertility. Lysozyme activities were higher in seminal plasma of samples with high motility than in those with low motility while seminal plasma and spermatozoal immunoglobulin concentrations (T-Ig, IgG) were increased in samples with low motility in comparison to samples with high motility. Seminal plasma and spermatozoal IgG concentrations and seminal plasma lysozyme activities showed significant correlations with the sperm motility rate and swimming velocity. Moreover, lysozyme improved the viability of spermatozoa in in vitro experiments. Possible physiological meanings of these results are discussed.     

In vitro and in vivo pharmacology of CP-945,598, a potent and selective cannabinoid CB1 receptor antagonist for the management of obesity

Cannabinoid CB₁ receptor antagonists exhibit pharmacologic properties favorable for the treatment of metabolic disease. CP-945,598 (1-[9-(4-chlorophenyl)-8-(2-chlorophenyl)-9H-purin-6-yl]-4-ethylamino piperidine-4-carboxylic acid amide hydrochloride) is a recently discovered selective, high affinity, competitive CB₁ receptor antagonist that inhibits both basal and cannabinoid agonist-mediated CB₁ receptor signaling in vitro and in vivo. CP-945,598 exhibits sub-nanomolar potency at human CB₁ receptors in both binding (K_i = 0.7 nM) and functional assays (K_i = 0.2 nM). The compound has low affinity (K_i = 7600 nM) for human CB₂ receptors. In vivo, CP-945,598 reverses four cannabinoid agonist-mediated CNS-driven responses (hypo-locomotion, hypothermia, analgesia, and catalepsy) to a synthetic cannabinoid receptor agonist. CP-945,598 exhibits dose and concentration-dependent anorectic activity in two models of acute food intake in rodents, fast-induced re-feeding and spontaneous, nocturnal feeding. CP-945,598 also acutely stimulates energy expenditure in rats and decreases the respiratory quotient indicating a metabolic switch to increased fat oxidation. CP-945,598 at 10 mg/kg promoted a 9%, vehicle adjusted weight loss in a 10 day weight loss study in diet-induced obese mice. Concentration/effect relationships combined with ex vivo brain CB₁ receptor occupancy data were used to evaluate efficacy in behavioral, food intake, and energy expenditure studies. Together, these in vitro, ex vivo, and in vivo data indicate that CP-945,598 is a novel CB₁ receptor competitive antagonist that may further our understanding of the endocannabinoid system.