The Arabidopsis thaliana FASCICLIN LIKE ARABINOGALACTAN PROTEIN 4 gene acts synergistically with abscisic acid signalling to control root growth

Background and Aims

The putative FASCICLIN-LIKE ARABINOGALACTAN PROTEIN 4 (At-FLA4) locus of Arabidopsis thaliana has previously been shown to be required for the normal growth of wild-type roots in response to moderately elevated salinity. However, the genetic and physiological pathway that connects At-FLA4 and normal root growth remains to be elucidated.

Methods

The radial swelling phenotype of At-fla4 was modulated with growth regulators and their inhibitors. The relationship of At-FLA4 to abscisic acid (ABA) signalling was analysed by probing marker gene expression and the observation of the At-fla4 phenotype in combination with ABA signalling mutants.

Key Results

Application of ABA suppresses the non-redundant role of At-FLA4 in the salt response. At-FLA4 positively regulates the response to low ABA concentration in roots and is required for the normal expression of ABA- and abiotic stress-induced genes. The At-fla4 phenotype is enhanced in the At-abi4 background, while two genetic suppressors of ABA-induced gene expression are required for salt oversensitivity of At-fla4. Salt oversensitivity in At-fla4 is suppressed by the CYP707A inhibitor abscinazole E2B, and salt oversensitivity in At-fla4 roots is phenocopied by chemical inhibition of ABA biosynthesis.

Conclusions

The predicted lipid-anchored glycoprotein At-FLA4 positively regulates cell wall biosynthesis and root growth by modulating ABA signalling.     

Determining mutations in G6PC and SLC37A4 genes in a sample of Brazilian patients with glycogen storage disease types Ia and Ib

Glycogen storage disease (GSD) comprises a group of autosomal recessive disorders characterized by deficiency of the enzymes that regulate the synthesis or degradation of glycogen. Types Ia and Ib are the most prevalent; while the former is caused by deficiency of glucose-6-phosphatase (G6Pase), the latter is associated with impaired glucose-6-phosphate transporter, where the catalytic unit of G6Pase is located. Over 85 mutations have been reported since the cloning of G6PC and SLC37A4 genes. In this study, twelve unrelated patients with clinical symptoms suggestive of GSDIa and Ib were investigated by using genetic sequencing of G6PC and SLC37A4 genes, being three confirmed as having GSD Ia, and two with GSD Ib. In seven of these patients no mutations were detected in any of the genes. Five changes were detected in G6PC, including three known point mutations (p.G68R, p.R83C and p.Q347X) and two neutral mutations (c.432G > A and c.1176T > C). Four changes were found in SLC37A4: a known point mutation (p.G149E), a novel frameshift insertion (c.1338_1339insT), and two neutral mutations (c.1287G > A and c.1076-28C > T). The frequency of mutations in our population was similar to that observed in the literature, in which the mutation p.R83C is also the most frequent one. Analysis of both genes should be considered in the investigation of this condition. An alternative explanation to the negative results in this molecular study is the possibility of a misdiagnosis. Even with a careful evaluation based on laboratory and clinical findings, overlap with other types of GSD is possible, and further molecular studies should be indicated.     

CTLA4CT60 gene polymorphism is not associated with differential susceptibility to pemphigus foliaceus

Pemphigus foliaceus is an organ-specific autoimmune disease characterized by autoantibodies against the extracellular region of desmoglein 1, a protein that mediates intercellular adhesion in desmosomes. Cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) is a key negative regulator of the T cell immune response, playing an important role in T cell homeostasis and maintenance of peripheral tolerance. Polymorphisms in the CTLA4 gene have been associated with autoimmune diseases and the functional CT60 single nucleotide polymorphism (rs3087243, also named 6230G > A) has been proposed to be a casual variant in several of these diseases. The aim of this study was to ascertain whether this polymorphism is associated with inter-individual variation in susceptibility to pemphigus foliaceus. The population sample in this case-control association study comprised 248 patient and 367 controls. We did not found a significant association of pemphigus foliaceus with the CT60 variants. We conclude that the CTLA4CT60 polymorphism is not an important factor for pemphigus foliaceus pathogenesis in the population analyzed.     

Localization of strawberry (Fragaria x ananassa) and Methylobacterium extorquens genes of strawberry flavor biosynthesis in strawberry tissue by in situ hybridization

Strawberry flavor is one of the most popular fruit flavors worldwide, with numerous applications in the food industry. In addition, the biosynthetic origin of the most important strawberry flavor components, such as 2,5-dimethyl-4-hydroxy-2H-furan-3-one (DMHF), is a challenging research area. DMHF's precursor, 2-hydroxy-propanal (or lactaldehyde), is biosynthesized by the endophytic bacterium Methylobacterium extorquens (M. extorquens). In particular, the alcohol dehydrogenase (ADH) enzymes of M. extorquens are involved in the biogenesis of DMHF precursors since they have the capacity to oxidize the strawberry-derived 1,2-propanediol to lactaldehyde. In this study, the expression of the endophytic ADH and the plant DMHF biosynthesis genes was examined in the tissues of raw and ripe strawberry receptacles by in situ hybridization. The presence of endophytic bacteria was studied in the same tissues by probes targeting bacterial 16S ribosomal ribonucleic acid. Hybridization signals of probes specific for endophytic ADH and plant DMHF biosynthesis genes, as well as bacteria-specific probes, were detected in the same locations. The probes were localized near the plasma membranes or intercellular spaces of cortical and vascular tissues of the receptacle, and intracellularly in the tissues of achenes. By localizing the expression of the endophytic methanol ADH and plant DMHF biosynthesis genes to the same tissues, we have reinforced our original hypothesis that an intimate symbiotic relationship between strawberry and endophytic cells exists and leads to the biosynthesis of DMHF.     

Association of interleukin-13 SNP rs20541 with allergic rhinitis risk: A meta-analysis

Studies investigating the association between interleukin-13 (IL-13) single nucleotide polymorphism (SNP) rs20541 and allergic rhinitis (AR) risk have reported conflicting results. The aim of the present study was to conduct a meta-analysis assessing the possible association of IL-13 SNP rs20541 with AR risk. Eight studies were included in the present meta-analysis (2153 cases and 3931 controls). The combined results based on all studies showed that IL-13 SNP rs20541 was associated with increased AR risk (Gln versus Arg: odds ratio (OR) = 1.18, 95% confidence interval (CI) = 1.08–1.30; Gln/Gln versus Arg/Arg: OR = 1.52, 95% CI = 1.20–1.92; Arg/Gln + Gln/Gln versus Arg/Arg: OR = 1.19, 95% CI = 1.06–1.33; Gln/Gln versus Arg/Gln + Arg/Arg: OR = 1.42, 95% CI = 1.13–1.79). When stratifying for race, IL-13 SNP rs20541 exhibited increased AR risk in Asians (Gln versus Arg: OR = 1.20, 95% CI = 1.06–1.36; Gln/Gln versus Arg/Arg: OR = 1.57, 95% CI = 1.17–2.12; Arg/Gln + Gln/Gln versus Arg/Arg: OR = 1.22, 95% CI = 1.04–1.44; Gln/Gln versus Arg/Gln + Arg/Arg: OR = 1.45, 95% CI = 1.09–1.93), while no significant association was detected in Caucasians (Gln versus Arg: OR = 1.28, 95% CI = 0.93 ~ 1.78; Gln/Gln versus Arg/Arg: OR = 1.42, 95% CI = 0.96–2.11; Arg/Gln + Gln/Gln versus Arg/Arg: OR = 1.35, 95% CI = 0.89–2.05; Gln/Gln versus Arg/Gln + Arg/Arg: OR = 1.37, 95% CI = 0.93–2.02). This meta-analysis supported that IL-13 SNP rs20541 was associated with AR, particularly in Asians.     

Association of interleukin-13 SNP rs1800925 with allergic rhinitis risk: A meta-analysis based on 1,411 cases and 3169 controls

Studies investigating the association between interleukin-13 (IL-13) single nucleotide polymorphism (SNP) rs1800925 and allergic rhinitis risk have reported conflicting results. The aim of the present study was to conduct a meta-analysis assessing the possible association of IL-13 SNP rs1800925 with allergic rhinitis risk. The relevant studies were identified through a search of PubMed, Embase, ISI Web of Knowledge and Chinese National Knowledge Infrastructure until December 2011 and selected on the basis of the established inclusion criteria for publications. Five studies were included in the present meta-analysis (1411 cases and 3169 controls). The combined results based on all studies showed that IL-13 SNP rs1800925 was not associated with increased allergic rhinitis risk (T versus C: odds ratio (OR)=1.06, 95% confidence interval (CI)=0.94-1.20; C/T versus C/C: OR=1.12, 95% CI=0.97-1.29; T/T versus C/C: OR=1.00, 95% CI=0.69-1.44; C/T+T/T versus CC: OR=1.10, 95% CI=0.96-1.27; T/T versus C/C+C/T: OR=0.91, 95% CI=0.64-1.31). This meta-analysis supported that IL-13 SNP rs1800925 was not associated with allergic rhinitis.     

Involvement of 1,25D3-MARRS (membrane associated, rapid response steroid-binding), a novel vitamin D receptor, in growth inhibition of breast cancer cells

In addition to classical roles in calcium homeostasis and bone development, 1,25 dihydroxyvitamin D₃ [1,25(OH)₂D₃] inhibits the growth of several cancer types, including breast cancer. Although cellular effects of 1,25(OH)₂D₃ traditionally have been attributed to activation of a nuclear vitamin D receptor (VDR), a novel receptor for 1,25(OH)₂D₃ called 1,25D₃-MARRS (membrane-associated, rapid response steroid-binding) protein was identified recently. The purpose of this study was to determine if the level of 1,25D₃-MARRS expression modulates 1,25(OH)₂D₃ activity in breast cancer cells.Relative levels of 1,25D₃-MARRS protein in MCF-7, MDA MB 231, and MCF-10A cells were estimated by real-time RT-PCR and Western blotting. To determine if 1,25D₃-MARRS receptor was involved in the growth inhibitory effects of 1,25(OH)₂D₃ in MCF-7 cells, a ribozyme construct designed to knock down 1,25D₃-MARRS mRNA was stably transfected into MCF-7 cells. MCF-7 clones in which 1,25D₃-MARRS receptor expression was reduced showed increased sensitivity to 1,25(OH)₂D₃ ( IC₅₀ 56 ± 24 nM) compared to controls (319 ± 181 nM; P < 0.05). Reduction in 1,25D₃-MARRS receptor lengthened the doubling time in transfectants treated with 1,25(OH)₂D₃. Knockdown of 1,25D₃-MARRS receptor also increased the sensitivity of MCF-7 cells to the vitamin D analogs KH1060 and MC903, but not to unrelated agents (all-trans retinoic acid, paclitaxel, serum/glucose starvation, or the isoflavone, pomiferin). These results suggest that 1,25D₃-MARRS receptor expression interferes with the growth inhibitory activity of 1,25(OH)₂D₃ in breast cancer cells, possibly through the nuclear VDR. Further research should examine the potential for pharmacological or natural agents that modify 1,25D₃-MARRS expression or activity as anticancer agents.     

Leishmania donovani: identification of novel vaccine candidates using human reactive sera and cell lines

Leishmaniasis is a complex of diseases caused by protozoan parasites belonging to the genus Leishmania. The development of specific resistance against re-infection after cure suggests that a vaccine approach is feasible. Various studies in humans and experimental animals strongly suggest that Th1 type of cell-mediated immune response is important for protection against the disease. A defined antigen that could elicit a specific T-cell-mediated immune response in the host would be an ideal candidate for the vaccine against this parasite. In order to select a candidate antigen, we established a screening system to identify the recombinant clone, expressing antigen having T-cell epitopes from a cDNA library. We screened the library using an established Leishmania specific cell line (LSCL) from a naive healthy human subject. The cell line with predominantly CD4+ cells behaved in a Leishmania specific manner. Fifty-two immuno-reactive clones were screened against the LSCL in vitro and we identified three cDNA clones expressing recombinant antigens that could induce proliferation of these cells to produce INFgamma. The protective efficacy of one of these recombinant proteins was investigated in a hamster model of experimental visceral leishmaniasis and showed protection against a virulent challenge. The identified antigens might be potential candidates for vaccine against Leishmania.     

A behavioral study of healthy and cancer genes by modeling electrical network

In recent years, gene network modeling is gaining popularity in genomics to monitor the activity profile of genes. More specifically, the objective of the network modeling concept is to study the genetic behavior associated with disease. Previous researchers have designed network model at nucleotide level which produces more complexity for designing circuits mostly in case of gene expression studies. Whereas the authors have designed the present network model, based on amino acid level which is simpler as well as more appropriate for prediction of the genetic abnormality. In the present concept, SISO continuous and discrete system models of genes are realized using Foster network. The model is designed based on hydropathy index value of amino acids to study the biological system behavior. The time and phase response in continuous (s) domain and pole-zero distribution in discrete (z) domain are used as measurement metric in the present study. The simulated responses of the system show genetic instability for cancer genes which truly reflects the medical reports. The proposed modeling concept can be used, to accurately identify or separate out the diseased genes from healthy genes.     

Subunit a of the F1F0 ATP Synthase Requires YidC and SecYEG for Membrane Insertion

The insertion of inner membrane proteins in Escherichia coli occurs almost exclusively via the SecYEG pathway, while some membrane proteins require the membrane protein insertase YidC. In vitro analysis demonstrates that subunit a of the F₁F₀ ATP synthase (F₀a) is strictly dependent on Ffh, SecYEG and YidC for its membrane insertion but independent of the proton motive force. The insertion of the first transmembrane segment of F₀a also depends on Ffh and SecYEG but not on YidC, whereas the insertion is strongly dependent on the proton motive force, unlike the full-length F₀a protein. These data demonstrate an extensive role of YidC in the assembly of the F₀ sector of the F₁F₀ ATP synthase.     

High prevalence Giardia duodenalis assemblage B and potentially zoonotic subtypes in sporadic human cases in Western Australia

Giardia duodenalis is a widespread parasite of mammalian species, including humans. Fecal samples from sporadic human clinical cases of giardiasis in Western Australia were analysed at two loci; 18S rRNA and glutamate dehydrogenase (gdh), and G. duodenalis assemblage B isolates were identified in 75% of isolates. Sequence analyses of 124 isolates at the 18S rRNA locus identified 93 isolates as assemblage B and 31 as assemblage A. Analyses of 109 isolates at the gdh locus identified 44 as B3, 38 as B4 and 27 were A2. Infection with Giardia was highest amongst children <5 years of age, with >56% of infections in this age group. The majority of the isolates were from rural areas (91/124) compared with urban areas (33/124). The assemblage A isolates were completely homogenous genetically at the gdh locus, while assemblage B isolates showed variability at the nucleotide but not at the amino acid level at this locus. Some of the assemblage B3 and B4 subtypes identified in humans were previously identified in marsupials in Australia and in a fox, indicating potential zoonotic transmission.