Effect of NaCl stress on rice physiological properties

Salinity is a major yield-reducing factor in coastal and arid irrigated rice production systems. Rice seedlings (Oryza sativa cv. Tarom Atri) were exposed to different NaCl concentrations for 8 days after germination. Plants height, fresh and dry weight, relative water content, pigment and carbohydrate content, photosynthetic efficiency and lipid peroxidase and antioxidant enzyme activity of rice seedlings grown under salt stress were investigated. Seedling grown under 25and 50 mM salt were shorter than the control. They could, however, develop their secondary leaves. Seedlings grown in the nutrient solution supplied with 100 and 200 mM extra salt could not develop their secondary leaves. Fresh weight ofseedlings grown under salt stress reduced up to 42.2% of the non-treated seedlings. Chlorophylls and carotenoids contents decreased significantly in the salt-treated seedlings. Carotenoid contents in NaCl-treated seedlings were decreased to 39.3%. No significant changes occurred in the photochemical efficiency of control and stressed plants. Increasing concentrations of NaCl resulted in increase and decrease of Na⁺ and K⁺ ions, respectively. NaCl salinity caused an increase in both peroxide content and lipid peroxidation. Seedlings which recovered for 24 h showed lower peroxide and malondialdehyde content.     

Lateral root development in the maize (Zea mays) lateral rootless1 mutant

Background and Aims

The maize lrt1 (lateral rootless1) mutant is impaired in its development of lateral roots during early post-embryonic development. The aim of this study was to characterize, in detail, the influences that the mutation exerts on lateral root initiation and the subsequent developments, as well as to describe the behaviour of the entire plant under variable environmental conditions.

Methods

Mutant lrt1 plants were cultivated under different conditions of hydroponics, and in between sheets of moist paper. Cleared whole mounts and anatomical sections were used in combination with both selected staining procedures and histochemical tests to follow root development. Root surface permeability tests and the biochemical quantification of lignin were performed to complement the structural data.

Key Results

The data presented suggest a redefinition of lrt1 function in lateral roots as a promoter of later development; however, neither the complete absence of lateral roots nor the frequency of their initiation is linked to lrt1 function. The developmental effects of lrt1 are under strong environmental influences. Mutant primordia are affected in structure, growth and emergence; and the majority of primordia terminate their growth during this last step, or shortly thereafter. The lateral roots are impaired in the maintenance of the root apical meristem. The primary root shows disturbances in the organization of both epidermal and subepidermal layers. The lrt1-related cell-wall modifications include: lignification in peripheral layers, the deposition of polyphenolic substances and a higher activity of peroxidase.

Conclusions

The present study provides novel insights into the function of the lrt1 gene in root system development. The lrt1 gene participates in the spatial distribution of initiation, but not in its frequency. Later, the development of lateral roots is strongly affected. The effect of the lrt1 mutation is not as obvious in the primary root, with no influences observed on the root apical meristem structure and maintenance; however, development of the epidermis and cortex are impaired.     

Signaling role of nitric oxide in the induction of plant defense by exogenous application of abiotic inducers

The objective of this work was to search out the probable molecule behind the activation of broad spectrum resistance during abiotic elicitors such as arachidonic acid, cupric chloride, chitosan, isonicotinic acid and salicylic acid mediated induced systemic resistance (ISR) in Raphanus sativus L. The elicitor compounds were sprayed on the radish leaves of healthy plant and after 24 h incubation a significant increase of β-1,3 glucanase, peroxidase, polyphenol oxidase and phenolics as well as a remarkable increase of nitric oxide (NO), a probable potent defense-signaling molecule in plant, was observed. Furthermore, treatment of the host with NO donor, sodium nitroprusside, also induced the same defense molecules. The results suggests that NO might be the signaling molecule during abiotic elicitor mediated ISR induction in the host system.     

Plasmodium falciparum RuvB1 is an active DNA helicase and translocates in the 5′–3′ direction

RuvB family of protein contains two similar kinds of proteins i.e. RuvB1 and RuvB2 from yeast to human. These proteins belong to the AAA + class of proteins and are critical components of several multiprotein complexes involved in diverse cellular activities. There are two RuvB proteins annotated in the Plasmodium database but the identification of the third protein recently by our lab has raised the question why Plasmodium falciparum contains three RuvB proteins instead of two. Hence the biochemical characterizations of these proteins have become essential to understand the role of these proteins in the malaria parasite. Recently we have reported the characterization of the recombinant PfRuvB3, which contains ATPase activity but lacks DNA helicase activity. In the present study we report the phylogenetic analysis and detailed biochemical characterization of one of the other RuvB homologue RuvB1 from P. falciparum. PfRuvB1 shows considerable homology with human as well as yeast RuvB1 and contains Walker motif A and Walker motif B. The activity analysis of this protein revealed that PfRuvB1 is an ATPase and this activity increased significantly in the presence of ss-DNA. PfRuvB1 also contains DNA helicase activity and translocates preferentially in 5′ to 3′ direction. In vivo investigation of PfRuvB1 revealed that it is constitutively expressed during all the stages of intraerythrocytic cycle of P. falciparum and localizes mainly to the nucleus. These studies will make important contribution in understanding the role of RuvB protein in P. falciparum.     

Subtractive phage display technology identifies zebrafish marcksb that is required for gastrulation

In the present study, we used a phage display technique to screen differentially expressed proteins from zebrafish post-gastrula embryos. With a subtractive screening approach, 6 types of single-chain Fv fragments (scFvs) were screened out from an scFv antibody phage display library by biopanning against zebrafish embryonic homogenate. Four scFv fragments (scFv1, scFv3, scFv4 and scFv6) showed significantly stronger binding to the tailbud embryos than to the 30%-epiboly embryos. A T7 phage display cDNA library was constructed from zebrafish tailbud embryos and used to identify the antigens potentially recognized by scFv1, which showed the highest frequency and strongest binding against the tailbud embryos. We acquired 4 candidate epitopes using scFv1 and the corresponding genes showed significantly higher expression levels at tailbud stage than at 30%-epiboly. The most potent epitope of scFv1 was the clone scFv1-2, which showed strong homology to zebrafish myristoylated alanine-rich C-kinase substrate b (Marcksb). Western blot analysis confirmed the high expression of marcksb in the post-gastrula embryos, and the endogenous expression of Marcksb was interfered by injection of scFv1. Zebrafish marcksb showed dynamic expression patterns during embryonic development. Knockdown of marcksb strongly affected gastrulation movements. Moreover, we revealed that zebrafish marcksb is required for cell membrane protrusion and F-actin alignment. Thus, our study uncovered 4 types of scFvs binding to zebrafish post-gastrula embryos, and the epitope of scFv1 was found to be required for normal gastrulation of zebrafish. To our knowledge, this was the first attempt to combine phage display technique with the embryonic and developmental study of vertebrates, and we were able to identify zebrafish marcksb that was required for gastrulation.     

Genetic associations with coronary heart disease: Meta-analyses of 12 candidate genetic variants

Aims

The aim of this study was to evaluate the combined contribution of 12 genetic variants to the risk of coronary heart disease (CHD).

Methods

Through a comprehensive literature search for genetic variants involved in the CHD association study, we harvested a total of 10 genes (12 variants) for the current meta-analyses. These genes consisted of GPX1 (rs1050450), PPARD (rs2016520), ALOX15 (rs34210653), SELPLG (rs2228315), FCGR2A (rs1801274), CCL5 (rs2107538), CYP1A1 (rs4646903), TP53 (rs1042522), CX37 (rs1764391), and PECAM1 (rs668, rs12953, and rs1131012).

Results

A total of 45 studies among 23,314 cases and 28,430 controls were retrieved for the meta-analyses of 12 genetic variants. The results showed a significant association between the GPX1 rs1050450 polymorphism and CHD (odd ratio (OR) = 1.61, 95% confidence interval (CI) = 1.25–2.07, P = 0.0002). Other meta-analyses of the rest 11 variants suggested a lack of association with the risk of CHD.

Conclusion

Our results confirmed that GPX1 rs1050450 was associated with susceptibility to CHD in Chinese and Indian populations.     

Therapeutic angiogenesis for revascularization in peripheral artery disease

Therapeutic angiogenesis for peripheral artery disease (PAD), achieved by gene and cell therapy, has recently raised a great deal of hope for patients who cannot undergo standard revascularizing treatment. Although pre-clinical studies gave very promising data, still clinical trials of gene therapy have not provided satisfactory results. On the other hand, cell therapy approach, despite several limitations, demonstrated more beneficial effects but initial clinical studies must be constantly validated by larger randomized, multi-center, double-blinded, placebo-controlled trials. This review focuses on previous and recent gene and cell therapy studies for limb ischemia, including both experimental and clinical research, and summarizes some important papers published in this field. Moreover, it provides a short comment on combined gene and cell therapy approach on the example of heme oxygenase-1 overexpressing cells with therapeutic properties.     

Synthesis,characterization and in vitro activity of a surface-attached antimicrobial cationic peptide

Infection associated with implanted biomaterials is common and costly and such infections are extremely resistant to antibiotics and host defenses. Consequently, there is a need to develop surfaces which resist bacterial adhesion and colonization. The broad spectrum synthetic cationic peptide melimine has been covalently linked to a surface via two azide linkers, 4-azidobenzoic acid (ABA) or 4-fluoro-3-nitrophenyl azide (FNA), and the resulting surfaces characterized by X-ray photoelectron spectroscopy and contact angle measurements. The quantity of bound peptide was estimated by a modified Bradford assay. The antimicrobial efficacy of the two melimine-modified surfaces against Pseudomonas aeruginosa and Staphylococcus aureus was compared by scanning electron microscopy (SEM) and fluorescence microscopy. Attachment of melimine via ABA gave an approximately 4-fold greater quantity of melimine bound to the surface than attachment via FNA. Surfaces melimine-modified by either attachment strategy showed significantly reduced bacterial adhesion for both strains of bacteria. P. aeruginosa exposed to ABA–melimine and FNA–melimine surfaces showed marked changes in cell morphology when observed by SEM and a reduction of approximately 15-fold (p < 0.001) in the numbers of adherent bacteria compared to controls. For the ABA–melimine surface there was a 33% increase in cells showing damaged membranes (p = 0.0016) while for FNA–melimine there was no significant difference. For S. aureus there were reductions in bacterial adhesion of approximately 40-fold (p < 0.0001) and 5-fold (p = 0.008) for surfaces modified with melimine via ABA or FNA, respectively. There was an increase in cells showing damaged membranes on ABA–melimine surfaces of approximately 87% (p = 0.001) compared to controls, while for FNA–melimine there was no significant difference observed. The data presented in this study show that melimine has excellent potential for development as a broad spectrum antimicrobial coating for biomaterial surfaces. Further, it was observed that the efficacy of antimicrobial activity is related to the method of attachment.