Enhancement of root hydraulic conductivity by methyl jasmonate and the role of calcium and abscisic acid in this process

The role of jasmonic acid in the induction of stomatal closure is well known. However, its role in regulating root hydraulic conductivity (L) has not yet been explored. The objectives of the present research were to evaluate how JA regulates L and how calcium and abscisic acid (ABA) could be involved in such regulation. We found that exogenous methyl jasmonate (MeJA) increased L of Phaseolus vulgaris, Solanum lycopersicum and Arabidopsis thaliana roots. Tomato plants defective in JA biosynthesis had lower values of L than wild‐type plants, and that L was restored by addition of MeJA. The increase of L by MeJA was accompanied by an increase of the phosphorylation state of the aquaporin PIP2. We observed that MeJA addition increased the concentration of cytosolic calcium and that calcium channel blockers inhibited the rise of L caused by MeJA. Treatment with fluoridone, an inhibitor of ABA biosynthesis, partially inhibited the increase of L caused by MeJA, and tomato plants defective in ABA biosynthesis increased their L after application of MeJA. It is concluded that JA enhances L and that this enhancement is linked to calcium and ABA dependent and independent signalling pathways.     

Combined effect between CHRNB3–CHRNA6 region gene variant (rs6474412) and smoking in psoriasis vulgaris severity

Background

Many factors associated with causing psoriasis have been reported, such as the genetic and environmental factors. Smoking is one of the well-established environmental risk factors for psoriasis and also associated with the disease severity. In addition, several studies of psoriasis and psoriatic arthritis have documented gene–environment interactions involving smoking behavior. Although gene polymorphisms on nicotinic acetylcholine receptor subunits CHRNB3–CHRNA6 region gene have been found to correlate with smoking behavior and lung cancer susceptibility in Chinese Han population, the combined effect between the smoking-related genetic variants and smoking behavior on psoriasis vulgaris (PV) has been unreported.

Objective

To evaluate the combined effect of the smoking-related (rs6474412-C/T) polymorphism on CHRNB3–CHRNA6 region gene and smoking behavior on PV risk and clinic traits in Chinese Han population.

Methods

A hospital-based case–control study including 672 subjects (355 PV cases and 317 controls) was conducted. The variant of rs6474412 was typed by SNaPshot Multiplex Kit (Applied Biosystems Co., USA).

Results

The higher body mass index (BMI ≥ 25), smoking behavior and alcohol consumption were risk factors for PV, and the estimated ORs were 1.55 (95% CI, 1.09–2.29), 1.74 (95% CI, 1.22–2.49) and 1.81 (95% CI, 1.25–2.62) respectively. The smoking patients had more severe conditions than non-smokers (OR = 1.71, 95% CI, 1.08–2.70, P = 0.020). The alleles and genotypes of rs6474412 were not associated with risk of PV, but the combined effect of rs6474412 genotype (TT) and smoking behavior increased severity of PV (OR = 5.95; 95% CI, 1.39–25.31; P < 0.05; adjusted OR = 2.20; 95% CI, 1.55–3.14; P < 0.001).

Conclusions

Our results demonstrate that the combined effect of rs6474412-C/T polymorphism in smoking-related CHRNB3–CHRNA6 region gene and smoking behavior may not confer risk to PV, but may have impact on PV severity in Chinese Han population.     

Sphingolipids in colon cancer

Colorectal cancer is one of the major causes of death in the western world. Despite increasing knowledge of the molecular signaling pathways implicated in colon cancer, therapeutic outcomes are still only moderately successful. Sphingolipids, a family of N-acyl linked lipids, have not only structural functions but are also implicated in important biological functions. Ceramide, sphingosine and sphingosine-1-phosphate are the most important bioactive lipids, and they regulate several key cellular functions. Accumulating evidence suggests that many cancers present alterations in sphingolipids and their metabolizing enzymes. The aim of this review is to discuss the emerging roles of sphingolipids, both endogenous and dietary, in colon cancer and the interaction of sphingolipids with WNT/β-catenin pathway, one of the most important signaling cascades that regulate development and homeostasis in intestine. This article is part of a Special Issue entitled New Frontiers in Sphingolipid Biology.     

Role of cholesterol sulfate in epidermal structure and function: Lessons from X-linked ichthyosis

X-linked ichthyosis is a relatively common syndromic form of ichthyosis most often due to deletions in the gene encoding the microsomal enzyme, steroid sulfatase, located on the short area of the X chromosome. Syndromic features are mild or unapparent unless contiguous genes are affected. In normal epidermis, cholesterol sulfate is generated by cholesterol sulfotransferase (SULT2B1b), but desulfated in the outer epidermis, together forming a ‘cholesterol sulfate cycle’ that potently regulates epidermal differentiation, barrier function and desquamation. In XLI, cholesterol sulfate levels my exceed 10% of total lipid mass (≈ 1% of total weight). Multiple cellular and biochemical processes contribute to the pathogenesis of the barrier abnormality and scaling phenotype in XLI. This article is part of a Special Issue entitled The Important Role of Lipids in the Epidermis and their Role in the Formation and Maintenance of the Cutaneous Barrier. Guest Editors: Kenneth R. Feingold and Peter Elias.     

Higher taxa vs. functional guilds vs. trophic groups as indicators of soil nematode diversity and community structure

Biodiversity surrogates are often used in ecology to save money and time. One such widely used surrogacy method is the higher taxon approach, also known in the literature as taxonomic sufficiency. This approach has rarely been applied to microscopic organisms like soil microfauna, although there is a lack of detailed taxonomic knowledge regarding the latter. We tested taxonomic sufficiency for genus alpha and beta diversity, as well as for community structure of soil nematodes. We also tested whether the functional classifications of nematodes into functional guilds and trophic groups can serve as efficient indicators of nematode diversity and community structure. We used data from soil nematode communities from five different microhabitats (soil, soil moss, rock moss, low tree trunk moss and high tree trunk moss) in forested and non forested areas at five different stations (differing in elevation and aspect). Our results showed that both the higher taxon approach and the functional surrogacy approach could serve as reliable indicators of alpha and beta diversity. Furthermore, our community analysis of both taxonomic and functional composition identified that the variability at the finer scales, and namely the habitat structure, played the leading role in shaping nematode communities.     

Valine uptake in the tap root of sugar beet: a comparative analysis with sucrose uptake

Given the lack of data on the absorption of amino acids in the tap root of Beta vulgaris, we studied the uptake of valine and compared it with that of sucrose at the same concentration (1 mM). The uptake of both substrates shared some similar characteristics. In particular, the absorption in both cases was controlled by an active process as evidenced by the inhibitory effect of CCCP and inhibitors of ATPases (DES, DCCD, orthovanadate). Both absorptions also involved the thiol and histidyl groups of protein carriers included in the plasmalemma as shown by treatment with specific compounds (PCMBS, mersalyl, NEM) inhibiting the transport of the nutrients in tissues and in purified PMV. However, it was shown that these uptakes present major differences. Firstly, unlike sucrose uptake, valine uptake was very sensitive to transmembrane electrical potential. Indeed, hyperpolarizing treatment with FC increased valine uptake but did not modify sucrose uptake. By contrast, treatment with high concentrations of KCl, which should result in depolarization of the cells, considerably decreased valine uptake and activated sucrose uptake. Secondly, ion mobilizations were different in the two types of transport. Unlike sucrose, application of valine to tissues strongly modified the time course of H⁺ influx. By contrast, sucrose uptake was controlled by K⁺ involvement as shown by effects either of modulators of K⁺ mobilization (LiCl, TEA) or of treatments inducing K⁺ starvation from the external medium.