脂多糖通过补体途径诱导小鼠产生白三烯B4

目的:研究脂多糖(LPS)对人血清中补体系统的激活及在小鼠模型中诱导产生白三烯B4(LTB4)。方法:LPS包被ELISA板,利用血清中补体C4、C3沉积实验检测补体成分被LPS活化的情况,通过尾静脉注射小鼠LPS后不同时间点ELISA定量检测LTB4,评价补体系统的活化和炎症因子的产生。结果与结论:血清系统ELISA检测发现LPS可以激活补体系统,且以凝集素途径为主;动物实验中LTB4被LPS诱导后1～3 h达到峰值,之后回落。C1INH对血清补体活化和动物模型中LTB4的产生均有显著抑制。     

Effect of <Emphasis Type="Italic">HXT</Emphasis> 1 and <Emphasis Type="Italic">HXT</Emphasis> 7 hexose transporter overexpression on wild-type and lactic acid producing <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis> cells

Background  

Since about three decades, Saccharomyces cerevisiae can be engineered to efficiently produce proteins and metabolites. Even recognizing that in baker's yeast one determining step for the glucose consumption rate is the sugar uptake, this fact has never been conceived to improve the metabolite(s) productivity.     

Slipped-strand mispairing: a major mechanism for DNA sequence evolution

Simple repetitive DNA sequences are a widespread and abundant feature of genomic DNA. The following several features characterize such sequences: (1) they typically consist of a variety of repeated motifs of 1-10 bases--but may include much larger repeats as well; (2) larger repeat units often include shorter ones within them; (3) long polypyrimidine and poly-CA tracts are often found; and (4) tandem arrangements of closely related motifs are often found. We propose that slipped-strand mispairing events, in concert with unequal crossing- over, can readily account for all of these features. The frequent occurrence of long tandem repeats of particular motifs (polypyrimidine and poly-CA tracts) appears to result from nonrandom patterns of nucleotide substitution. We argue that the intrahelical process of slipped-strand mispairing is much more likely to be the major factor in the initial expansion of short repeated motifs and that, after initial expansion, simple tandem repeats may be predisposed to further expansion by unequal crossing-over or other interhelical events because of their propensity to mispair. Evidence is presented that single-base repeats (the shortest possible motifs) are represented by longer runs in mammalian introns than would be expected on a random basis, supporting the idea that SSM may be a ubiquitous force in the evolution of the eukaryotic genome. Simple repetitive sequences may therefore represent a natural ground state of DNA unselected for coding functions.      

Photocatalytic TiO2 coating-to reduce ammonia and greenhouse gases concentration and emission from animal husbandries

Animal production is a main source of NH3 emission into the environment and a significant producer of other polluting gases. Most of the best available techniques (BAT) that could be used today are not very widely applied in the field because of costs, especially in existing livestock buildings. Industrial applications show that TiO2 catalytic paint can be used to transform NH3 into N2, N2O or NO and water. Field experiments aimed at determining effects on indoor air quality and NH3 and polluting gas emissions into the environment of coating pig house walls with TiO2 catalytic paint and to assess the potential efficiency of this simple painting technique as a low cost BAT technique for animal farmers. The trial was performed in two identical mechanical ventilated farrowing rooms in a swine farm in Northern Italy. Environmental parameters, ventilation rate and gas concentrations were continuously monitored in the two units throughout a 28 day production cycle. NH3, N2O, CO2, CH4 average concentrations of 5.41, 1.18, 6.28 and 2109.38 mg m(-3) (reference unit without treatment) and 3.76, 1.13, 5.32 and 1881.64 mg m(-3) (experimental unit) were, respectively, recorded during a full farrowing cycle. Pollutant emissions, expressed on a Livestock Unit (LU, i.e., 500 kg live weight) basis, were 16.33, 3.57, 18.96 and 6365.01 kg y(-1)LU(-1) (reference unit) and 11.37, 3.43, 16.11 and 5695.58 kg y(-1) LU(-1) (experimental unit), respectively. Significantly higher pollutant concentrations and emissions were found in the untreated reference unit, under similar environmental conditions and with identical numbers of sows and piglets per unit.     

Mutations of the CK2 phosphorylation site of Sic1 affect cell size and S-Cdk kinase activity in Saccharomyces cerevisiae

By sequence analysis we found an amino acid stretch centred on Serine201 matching a stringent CK2 consensus site within the C-terminal, inhibitory domain of Sic1. Here we show by direct mass spectrometry analysis that Sic1, but not a mutant protein whose CK2 phospho-acceptor site has been mutated to alanine, Sic1S201A, is actually phosphorylated in vitro by CK2 on Serine 201. Mutation of Serine 201 alters the coordination between growth and cell cycle progression. A significant increase of average protein content and of the average protein content at the onset of DNA synthesis is observed for exponentially growing cells harbouring the Sic1S201A protein. A strong reduction of the same parameters is observed in cells harbouring Sic1S201E. The deregulated coordination between cell size and cell cycle is also apparent at the level of S-Cdk activity.     

Effects of umbilical cord blood stem cells on healing factors for diabetic foot injuries

The use of stem or progenitor cells from bone marrow, or peripheral or umbilical cord blood is becoming more common for treatment of diabetic foot problems. These cells promote neovascularization by angiogenic factors and they promote epithelium formation by stimulating cell replication and migration under certain pathological conditions. We investigated the role of CD34 + stem cells from human umbilical cord blood in wound healing using a rat model. Rats were randomly divided into a control group and two groups with diabetes induced by a single dose of 55 mg/kg intraperitoneal streptozocin. Scarred areas 5 mm in diameter were created on the feet of all rats. The diabetic rats constituted the diabetes control group and a diabetes + stem cell group with local injection into the wound site of 0.5 × 106 CD34 + stem cells from human umbilical cord blood. The newly formed skin in the foot wounds following CD34 + stem cell treatment showed significantly improvement by immunohistochemistry and TUNEL staining, and were closer to the wound healing of the control group than the untreated diabetic animals. The increase in FGF expression that accompanied the local injection of CD34 + stem cells indicates that FGF stimulation helped prevent apoptosis. Our findings suggest a promising new treatment approach to diabetic wound healing.     

High lipase production by Candida rugosa is associated with G1 cells. A flow cytometry study

Growth of C. rugosa on three different culture media was analysed by laser flow cytometry to evaluate physiological growth conditions allowing effective lipase production. The highest productivity was associated with an increased proportion of cells in the G1 phase and was independent of the effect of the medium on lipase formation.     

Morphologically-structured models of growing budding yeast populations

It has been well recognized that many key aspects of cell cycle regulation are encoded into the size distributions of growing budding yeast populations due to the tight coupling between cell growth and cell division present in this organism. Several attempts have been made to model the cell size distribution of growing yeast populations in order to obtain insight on the underlying control mechanisms, but most were based on the age structure of asymmetrically dividing populations. Here we propose a new framework that couples a morphologically-structured representation of the population with population balance theory to formulate a dynamic model for the size distribution of growing yeast populations. An advantage of the presented framework is that it allows derivation of simpler models that are directly identifiable from experiments. We show how such models can be derived from the general framework and demonstrate their utility in analyzing yeast population data. Finally, by employing a recently proposed numerical scheme, we proceed to integrate numerically the full distributed model to provide predictions of dynamics of the cell size structure of growing yeast populations.