Th1/Th2 cells, their associated molecules and role in pathophysiology

Cytokines, chemokines, and/or chemokine receptors associated with type 1 T helper (Th1) or Th2 cells play a role in different physiological conditions, such as T lymphopoiesis and pregnancy, as well as in pathological conditions, such as unexplained recurrent abortions, proliferative glomerulonephritis, and control of angiogenesis.     

How pregnancy can affect autoimmune diseases progression?

Autoimmune disorders are characterized by tissue damage, caused by self-reactivity of different effectors mechanisms of the immune system, namely antibodies and T cells. Their occurrence may be associated with genetic and/or environmental predisposition and to some extent, have implications for fertility and obstetrics. The relationship between autoimmunity and reproduction is bidirectional. This review only addresses the impact of pregnancy on autoimmune diseases and not the influence of autoimmunity on pregnancy development. Th17/Th1-type cells are aggressive and pathogenic in many autoimmune disorders and inflammatory diseases. The immunology of pregnancy underlies the role of Th2-type cytokines to maintain the tolerance of the mother towards the fetal semi-allograft. Non-specific factors, including hormonal changes, favor a switch to Th2-type cytokine profile. In pregnancy Th2, Th17/Th2 and Treg cells accumulate in the decidua but may also be present in the mother’s circulation and can regulate autoimmune responses influencing the progression of autoimmune diseases.     

Assessing the effect of solar radiation on plant salt tolerance as defined by the static and dynamic indices

Any interaction between plant salt tolerance and environment is critical to crop breeders, geneticists, molecular biologists, soil-water-crop modelers and all researchers interested in 'global change'. A common criterion used for plant salt tolerance is a threshold value of root zone salinity, a static index that delimits the onset of yield reduction. According to this criterion, it was discovered that tomato salt tolerance decreases significantly with reduced solar radiation. In contrast, the threshold values of a new index based on the dynamic processes of salt accumulation relative to growth, are invariant to solar radiation. The variability and stability of the respective indices provides new insights for accessing physical and biochemical processes governing plant response in saline environments.     

U.S. racial and ethnic relations in the twenty-first century

The study of U.S. racial and ethnic relations is often reduced to the study of racial or ethnic relations. This article reveals the limitations of a focus on ethnicity or race, in isolation, and instead urges a new framework that brings them together. We consider three cases that have been conceptualized by the ethnicity paradigm as assimilation projects and by the race paradigm as structural racism projects, respectively: (1) African-American entrepreneurs; (2) the Mexican middle class; and (3) black immigrant deportees. We reveal the shortcomings of the ethnicity paradigm to consider race as a structural force or to acknowledge that structural racism conditions incorporation in marked ways; and the limitations of the race paradigm to take seriously group members’ agency in fostering social capital that can mediate racial inequality. Instead, we offer a unifying approach to reveals how ethnicity and race condition members’ life chances within the U.S. social structure.     

Cloning and sequencing of four new metallothionein genes from Tetrahymena thermophila and T. pigmentosa: evolutionary relationships in Tetrahymena MT family

The structure of four new MT (metallothionein) genes of Tetrahymena thermophila and T. pigmentosa were characterized. The MT-2 genes from the two species are very similar, differing by 10 out of 2259 sequenced nucleotides, and the deduced amino acid sequences are identical. The MT-1 genes from T. pigmentosa and T. thermophila are also very similar, differing only by 3 nucleotides in the 5′-UT region. The promoter regions contain a TATA box and many stretches partially matching some regulatory elements such as metal-responsive (MREs), antioxidant-responsive (AREs), a CAAT box, a G-box, and AP1 and ACE-1 binding sites. The related coding and amino acid sequences were compared with those previously sequenced in Tetrahymena. This analysis revealed two independent events of duplication occurring in Cd- (MT-1 and MTT1) and Cu- (MT-2) induced MTs. This evolutionary pathway also explains the unusual length of these proteins, which are much longer than many MTs studied so far. Additionally, the orthology and paralogy relationships of the various MTs are presented. Finally, on the basis of phylogenetic analyses of Tetrahymena MTs, two evolutionary hypotheses are proposed.     

Simulation of shoot chloride accumulation: separation of physical and biochemical processes governing plant salt tolerance

The effect of growth under saline condition (100 mol m^-3 NaCl in the nutrient solution) on the influx and the efflux of glucose from roots of cotton plants was analysed utilising the non metabolisable glucose analogue [¹⁴C]-3-O-methylglucose ([¹⁴C]3-OMG). Apical segments (1 cm long) excised from cotton roots took up [¹⁴C]3-OMG. At each tested concentration (5–500 mmol m^-3), the influx was completely inhibited by the presence of the protonophore carbonylcyanide-m-chlorophenyl hydrazone (CCCP) indicating that it is mediated by a H⁺-coupled co-transport mechanism. The CCCP-sensitive [¹⁴C]3-OMG influx was lower in the root segments excised from plants grown on saline solution than in the controls, and this was particularly evident at lower external concentrations. This difference was not due to a lower H⁺ apoplastic availability. In fact, the saline condition did not affect the pH of the rhizosphere and indeed the H⁺–ATPase activity, evaluated in plasma membrane vesicles purified from saline-treated plants, was higher (+23%) than in the controls. The lower uptake of [¹⁴C]3-OMG into saline treated root segments was related to an enhanced value of the apparent K_m of the carrier for the glucose analogue. This effect is discussed in relation to either the more positive value of the transmembrane electric potential difference (ΔΨ) measured in these root segments, or a competitive inhibition of Na⁺ on the H⁺ binding site of the carrier. Growth in saline solution slightly affected the efflux of the [¹⁴C]3-OMG preloaded in root segments, changing the membrane permeability to the molecule. The results strongly suggest that the higher (2.5 fold) net exudation of glucose, observed in short-term (4 h) collection experiments, from roots of cotton plants grown in saline condition, is mainly due to an effect of the saline growth condition on the system involved in the reabsorption of the hexose rather than on its efflux. This revised version was published online in June 2006 with corrections to the Cover Date.     

<Emphasis Type="Italic">Paenibacillus</Emphasis> sp. A59 GH10 and GH11 Extracellular Endoxylanases: Application in Biomass Bioconversion

The cost-efficient degradation of xylan to fermentable sugars is of particular interest in second generation bioethanol production, feed, food, and pulp and paper industries. Multiple potentially secreted enzymes involved in polysaccharide deconstruction are encoded in the genome of Paenibacillus sp. A59, a xylanolytic soil bacterium, such as three endoxylanases, seven GH43 β-xylosidases, and two GH30 glucuronoxylanases. In secretome analysis of xylan cultures, ten glycoside hydrolases were identified, including the three predicted endoxylanases, confirming their active role. The two uni-modular xylanases, a 32-KDa GH10 and a 20-KDa GH11, were recombinantly expressed and their activity on xylan was confirmed (106 and 85 IU/mg, respectively), with differences in their activity pattern. Both endoxylanases released mainly xylobiose (X2) and xylotriose (X3) from xylan and pre-treated biomasses (wheat straw, barley straw, and sweet corn cob), although only rGH10XynA released xylose (X1). rGH10XynA presented optimal conditions at pH 6, with thermal stability at 45–50 °C, while rGH11XynB showed activity in a wider range of pH, from 5 to 9, and was thermostable only at 45 °C. Moreover, GH11XynB presented sigmoidal kinetics on xylan, indicating possible cooperative binding, which was further supported by the structural model. This study provides a detailed analysis of the complete set of carbohydrate-active enzymes encoded in Paenibacillus sp. A59 genome and those effectively implicated in hemicellulose hydrolysis, contributing to understanding the mechanisms necessary for the bioconversion of this polysaccharide. Moreover, the two main free secreted xylanases, rGH10XynA and rGH11XynB, were fully characterized, supporting their potential application in industrial bioprocesses on lignocellulosic biomass.