Simple and Effective Regeneration of Mungbean (Vigna radiata (L) Wilczek) using Cotyledonary Node Explants

Mungbean (Vigna radiata (L) Wilczek cv ML — 267) is a recalcitrant grain legume species. Direct multiple shoots were developed from the cotyledonary node explants of 2-day-old in vitro grown seedlings of mungbean. Maximum number of shoots (an average 12.1 shoots per explant) was obtained on a medium containing MS salts, B5 vitamins and 5.0 mg l^?1 BAP. A medium with lower BAP concentration appeared suitable for rapid shoot elongation. The elongated shoots were rooted on 0.2 mg l^?1 NAA. The rooted plants were acclimatized under field conditions. The survival of the plants in the greenhouse was 90 %. Plants flowered and set seed normally.     

Tandem combination of Trigonella foenum-graecum defensin (Tfgd2) and Raphanus sativus antifungal protein (RsAFP2) generates a more potent antifungal protein

Plant defensins are small (45 to 54 amino acids) positively charged antimicrobial peptides produced by the plant species, which can inhibit the growth of a broad range of fungi at micro-molar concentrations. These basic peptides share a common characteristic three-dimensional folding pattern with one α-helix and three β-sheets that are stabilized by eight disulfide-linked cysteine residues. Instead of using two single-gene constructs, it is beneficial when two effective genes are made into a single fusion gene with one promoter and terminator. In this approach, we have linked two plant defensins namely Trigonella foenum-graecum defensin 2 (Tfgd2) and Raphanus sativus antifungal protein 2 (RsAFP2) genes by a linker peptide sequence (occurring in the seeds of Impatiens balsamina) and made into a single-fusion gene construct. We used pET-32a+ vector system to express Tfgd2-RsAFP2 fusion gene with hexahistidine tag in Escherichia coli BL21 (DE3) pLysS cells. Induction of these cells with 1 mM IPTG achieved expression of the fusion protein. The solubilized His₆-tagged recombinant fusion protein was purified by immobilized-metal (Ni²⁺) affinity column chromatography. The final yield of the fusion protein was 500 ng/μL. This method produced biologically active recombinant His₆-tagged fusion protein, which exhibited potent antifungal action towards the plant pathogenic fungi (Botrytis cinerea, Fusarium moniliforme, Fusarium oxysporum, Phaeoisariopsis personata and Rhizoctonia solani along with an oomycete pathogen Phytophthora parasitica var nicotianae) at lower concentrations under in vitro conditions. This strategy of combining activity of two defensin genes into a single-fusion gene will definitely be a promising utility for biotechnological applications.     

Molecular Basis of Glycosaminoglycan Heparin Binding to the Chemokine CXCL1 Dimer

Glycosaminoglycan (GAG)-bound and soluble chemokine gradients in the vasculature and extracellular matrix mediate neutrophil recruitment to the site of microbial infection and sterile injury in the host tissue. However, the molecular principles by which chemokine-GAG interactions orchestrate these gradients are poorly understood. This, in part, can be directly attributed to the complex interrelationship between the chemokine monomer-dimer equilibrium and binding geometry and affinities that are also intimately linked to GAG length. To address some of this missing knowledge, we have characterized the structural basis of heparin binding to the murine CXCL1 dimer. CXCL1 is a neutrophil-activating chemokine and exists as both monomers and dimers (K_d = 36 μm). To avoid interference from monomer-GAG interactions, we designed a trapped dimer (dCXCL1) by introducing a disulfide bridge across the dimer interface. We characterized the binding of GAG heparin octasaccharide to dCXCL1 using solution NMR spectroscopy. Our studies show that octasaccharide binds orthogonally to the interhelical axis and spans the dimer interface and that heparin binding enhances the structural integrity of the C-terminal helical residues and stability of the dimer. We generated a quadruple mutant (H20A/K22A/K62A/K66A) on the basis of the binding data and observed that this mutant failed to bind heparin octasaccharide, validating our structural model. We propose that the stability enhancement of dimers upon GAG binding regulates in vivo neutrophil trafficking by increasing the lifetime of “active” chemokines, and that this structural knowledge could be exploited for designing inhibitors that disrupt chemokine-GAG interactions and neutrophil homing to the target tissue.     

Nonsteroidal Anti-inflammatory Drugs Diclofenac and Celecoxib Attenuates Wnt/β-Catenin/Tcf Signaling Pathway in Human Glioblastoma Cells

Glioblastoma, the most common and aggressive primary brain tumors, carry a bleak prognosis and often recur even after standard treatment modalities. Emerging evidence suggests that deregulation of the Wnt/β-catenin/Tcf signaling pathway contributes to glioblastoma progression. Nonsteroidal anti-inflammatory drugs (NSAIDs) inhibit tumor cell proliferation by suppressing Wnt/β-catenin/Tcf signaling in various human malignancies. In this study, we sought to inhibit Wnt/β-catenin/Tcf signaling in glioblastoma cells by the NSAIDs diclofenac and celecoxib. Both diclofenac and celecoxib significantly reduced the proliferation, colony formation and migration of human glioblastoma cells. Diclofenac and celecoxib downregulated β-catenin/Tcf reporter activity. Western and qRT-PCR analysis showed that diclofenac and celecoxib reduced the expression of β-catenin target genes Axin2, cyclin D1 and c-Myc. In addition, the cytoplasmic accumulation and nuclear translocation of β-catenin was significantly reduced following diclofenac and celecoxib treatment. Furthermore, diclofenac and celecoxib significantly increased phosphorylation of β-catenin and reduced the phosphorylation of GSK3β. These results clearly indicated that diclofenac and celecoxib are potential therapeutic agents against glioblastoma cells that act by suppressing the activation of Wnt/β-catenin/Tcf signaling.     

Pacemaker Lead Induced Inferior Vena Caval Thrombosis Leading to Portal Hypertension

Inferior vena caval thrombosis is an unusual complication of permanent pacemaker implantation. The clinical presentation due to thrombosis depends on the site of thrombus. We have described here a rare case of pacemaker lead associated thrombosis of inferior vena cava, its diagnostic work up and briefly reviewed the existing literature of this uncommon complication.     

HupB,a Nucleoid-Associated Protein of Mycobacterium tuberculosis,Is Modified by Serine/Threonine Protein Kinases In Vivo

HU, a widely conserved bacterial histone-like protein, regulates many genes, including those involved in stress response and virulence. Whereas ample data are available on HU-DNA communication, the knowledge on how HU perceives a signal and transmit it to DNA remains limited. In this study, we identify HupB, the HU homolog of the human pathogen Mycobacterium tuberculosis, as a component of serine/threonine protein kinase (STPK) signaling. HupB is extracted in its native state from the exponentially growing cells of M. tuberculosis H₃₇Ra and is shown to be phosphorylated on both serine and threonine residues. The STPKs capable of modifying HupB are determined in vitro and the residues modified by the STPKs are identified for both in vivo and the in vitro proteins through mass spectrometry. Of the identified phosphosites, Thr⁶⁵ and Thr⁷⁴ in the DNA-embracing β-strand of the N-terminal domain of HupB (N-HupB) are shown to be crucial for its interaction with DNA. In addition, Arg⁵⁵ is also identified as an important residue for N-HupB–DNA interaction. N-HupB is shown to have a diminished interaction with DNA after phosphorylation. Furthermore, hupB is shown to be maximally expressed during the stationary phase in M. tuberculosis H₃₇Ra, while HupB kinases were found to be constitutively expressed (PknE and PknF) or most abundant during the exponential phase (PknB). In conclusion, HupB, a DNA-binding protein, with an ability to modulate chromatin structure is proposed to work in a growth-phase-dependent manner through its phosphorylation carried out by the mycobacterial STPKs.     

Association between the risk of coronary artery disease in South Asians and a deletion polymorphism in glutathione S-transferase M1.

South Asians living in Western societies show a greater risk of coronary artery disease (CAD) than the indigenous Caucasian population, probably related to the change to a Westernised lifestyle and an associated genetic susceptibility. Modulation of DNA damage and mutation caused by polymorphisms in detoxification enzymes, including the glutathione S-transferases (GSTs), is a well-established risk factor for tobacco-related carcinogenesis, and a similar change in cellular damage may be involved in the risk of vascular disease associated with tobacco smoking. In this study we examined whether polymorphisms in GST genes influence the risk of CAD in a case-control group of South Asians, following our recent observation of such an association in Caucasians from the same region of the UK. Blood was obtained from 170 patients of South Asian origin admitted for angiographic investigation of chest pain and from 203 controls. Patients were subdivided into those with and without previous acute myocardial infarction (AMI), and DNA was analysed for deletions in the GSTM1 and GSTT1 genes. An association was found between the prevalence of the GSTM1 null genotype and the risk of developing CAD in this study population. The frequency of the null genotype was 52.7% in healthy controls and 41.2% in patients (odds ratio [OR] 0.63, 95% confidence interval [95% CI] 0.42-0.95, p = 0.029). The effect was similar in subjects with or without a prior history of AMI. The association was also independent of smoking history, with both non-smokers and smokers showing a similar pattern of genotype distribution, the frequency of the null genotype being 51.2% in controls versus 37.0% in patients in 'never' smokers (OR 0.56, 95% CI 0.33-0.94, p = 0.037) and 60.0% in controls versus 46.2% in patients in 'ever' smokers (OR 0.57, 95% CI 0.25-1.28, p = 0.223). The association remained after adjusting for age, sex, body mass index and the presence or absence of stenosis. No significant associations were observed between the GSTT1 genotype and cardiovascular disease (chi(2) test, p > 0.1). The results of this study indicate that the GSTM1 null genotype is protective against both CAD and AMI. However, further study is required in order to elucidate the, as yet unexplained, mechanisms underlying this association.     

Plant regeneration from hypocotyl-derived protoplasts of Brassica juncea (L.) Czern and Coss

Protoplasts isolated from etiolated hypocotyls of 6-day-old seedlings of Brassica juncea cv RLM 198 were cultured in a modified V₄₇ medium containing 7% mannitol, 2% sucrose, 1.0 mg/l 2,4-D, 0.1 mg/l NAA and 0.4 mg/l BAP, at a density of 5×10⁴ protoplasts per ml of medium. Cultures were incubated in the dark at 25+1°C. After 7 d of culture, cell colonies were diluted with 8_p medium containing 5% mannitol and a similar hormone combination as described earlier. After 14 d, cell colonies were embedded in 8_p medium containing agarose and 3.5% mannitol. Immediately upon gelling, liquid 8_p medium was added to each Petri dish as an overlayer, and cultures were incubated in the light. After a total of 3 to 4 weeks in culture, microcalli were obtained. A modified MS medium with 2% sucrose, 1.0 mg/l 2,4-D and 0.1 mg/l kinetin solidified with 0.5% agarose was used for growing microcalli into callus lines. On MS medium containing 2% sucrose, 0.1 mg/l IAA, 2.0 mg/l zeatin riboside and 2.0 mg/l BAP, solidified with 0.5% agarose, about 35% of the calli regenerated multiple shoots. The time required from culture of protoplasts to multiple shoot regeneration was about 10 weeks. Regenerated shoots were rooted and plants were re-established in a growth chamber at high frequency.Abbreviations 2,4-D 2,4-dichlorophenoxyacetic acid - IAA Indole-3-acetic acid - NAA -naphthaleneacetic acid - BAP 6-benzylaminopurine - IBA Indole-3-butyric acid