Genome duplication improves rice root resistance to salt stress

Background

Salinity is a stressful environmental factor that limits the productivity of crop plants, and roots form the major interface between plants and various abiotic stresses. Rice is a salt-sensitive crop and its polyploid shows advantages in terms of stress resistance. The objective of this study was to investigate the effects of genome duplication on rice root resistance to salt stress.

Results

Both diploid rice (HN2026-2x and Nipponbare-2x) and their corresponding tetraploid rice (HN2026-4x and Nipponbare-4x) were cultured in half-strength Murashige and Skoog medium with 150 mM NaCl for 3 and 5 days. Accumulations of proline, soluble sugar, malondialdehyde (MDA), Na⁺ content, H⁺ (proton) flux at root tips, and the microstructure and ultrastructure in rice roots were examined. We found that tetraploid rice showed less root growth inhibition, accumulated higher proline content and lower MDA content, and exhibited a higher frequency of normal epidermal cells than diploid rice. In addition, a protective gap appeared between the cortex and pericycle cells in tetraploid rice. Next, ultrastructural analysis showed that genome duplication improved membrane, organelle, and nuclei stability. Furthermore, Na⁺ in tetraploid rice roots significantly decreased while root tip H⁺ efflux in tetraploid rice significantly increased.

Conclusions

Our results suggest that genome duplication improves root resistance to salt stress, and that enhanced proton transport to the root surface may play a role in reducing Na⁺ entrance into the roots.     

Nomenclature report on rice WRKY's - Conflict regarding gene names and its solution

Background

Since whole genome sequences of rice were made publically accessible, the number of articles on new rice genes has increased remarkably. The Committee on Gene Symbolization, Nomenclature and Linkage (CGSNL) of the Rice Genetics Cooperative published the gene nomenclature system for rice and encouraged researchers to follow the rules before publishing their results. The CGSNL provides an on-line registration system for newly identified rice genes to prevent conflicts and/or duplication of gene name in journal articles.

Findings

Recently, the CGSNL surveyed genes in the rice WRKY family in published journal articles and found several duplicated gene names.

Conclusions

To discuss and resolve inconsistencies in WRKY gene nomenclature, the rice WRKY working group was established and redefined the nomenclature. This report announces the conclusion.     

OsSUV3 transgenic rice maintains higher endogenous levels of plant hormones that mitigates adverse effects of salinity and sustains crop productivity

Background

The SUV3 (suppressor of Var 3) gene encodes a DNA and RNA helicase, which is localized in the mitochondria. Plant SUV3 has not yet been characterized in detail. However, the Arabidopsis ortholog of SUV3 (AT4G14790) has been shown to be involved in embryo sac development. Previously, we have reported that rice SUV3 functions as DNA and RNA helicase and provides salinity stress tolerance by maintaining photosynthesis and antioxidant machinery. Here, we report further analysis of the transgenic OsSUV3 rice plants under salt stress.

Findings

The transgenic OsSUV3 overexpressing rice T₁ lines showed significantly higher endogenous content of plant hormones viz., gibberellic acid (GA₃), zeatin (Z) and indole-3-acetic acid (IAA) in leaf, stem and root as compared to wild-type (WT), vector control (VC) and antisense (AS) plants under salt (200 mM NaCl) stress condition. A similar trend of endogenous plant hormones profile was also reflected in the T₂ generation of OsSUV3 transgenic rice under defined parameters and stress condition.

Conclusions

In response to stress, OsSUV3 rice plants maintained plant hormone levels that regulate the expression of several stress-induced genes and reduce adverse effects of salt on plant growth and development and therefore sustains crop productivity.     

Isolation of a novel mutant gene for soil-surface rooting in rice (Oryza sativa L.)

Background

Root system architecture is an important trait affecting the uptake of nutrients and water by crops. Shallower root systems preferentially take up nutrients from the topsoil and help avoid unfavorable environments in deeper soil layers. We have found a soil-surface rooting mutant from an M₂ population that was regenerated from seed calli of a japonica rice cultivar, Nipponbare. In this study, we examined the genetic and physiological characteristics of this mutant.

Results

The primary roots of the mutant showed no gravitropic response from the seedling stage on, whereas the gravitropic response of the shoots was normal. Segregation analyses by using an F₂ population derived from a cross between the soil-surface rooting mutant and wild-type Nipponbare indicated that the trait was controlled by a single recessive gene, designated as sor1. Fine mapping by using an F₂ population derived from a cross between the mutant and an indica rice cultivar, Kasalath, revealed that sor1 was located within a 136-kb region between the simple sequence repeat markers RM16254 and 2935-6 on the terminal region of the short arm of chromosome 4, where 13 putative open reading frames (ORFs) were found. We sequenced these ORFs and detected a 33-bp deletion in one of them, Os04g0101800. Transgenic plants of the mutant transformed with the genomic fragment carrying the Os04g0101800 sequence from Nipponbare showed normal gravitropic responses and no soil-surface rooting.

Conclusion

These results suggest that sor1, a rice mutant causing soil-surface rooting and altered root gravitropic response, is allelic to Os04g0101800, and that a 33-bp deletion in the coding region of this gene causes the mutant phenotypes.     

Gene response in rice plants treated with continuous fog influenced by pH,was similar to that treated with biotic stress

Background

Throughout Asia, including Japan, rice plants are cultivated in a wide range of areas from lowlands to highlands and are frequently exposed to fog, including acid fog. Some physiological studies have shown that acid fog can be a stress factor for plants. We analyzed the gene expression profiles of rice plants treated with artificially prepared simulated acid fog (SiAF) or simulated neutral fog (SiNF) for 1 or 7 days.

Results

Microarray analysis results suggested that both the SiAF and the SiNF treatments induced the expression of genes involved in the defense and stress responses in rice plants. Induction of such genes was detected in plants treated with SiAF for 1 day, and the number of induced genes increased in plants treated with SiAF for 7 days. The genes for defense and stress responses were also induced by SiNF for 7 days, although they were not induced by SiNF for 1 day. The gene expression profiles of the SiAF-treated and the SiNF-treated plants were compared to those of plants treated with other stress factors. The comparison revealed that both SiAF and SiNF treatments have similar effects to biotic stresses and ozone stress. The genes encoding NADPH oxidase and germin, which function in apoplasts, were also induced by SiAF, SiNF and biotic stresses.

Conclusions

These findings suggest that both the SiAF and the SiNF treatments may result in oxidative stress through the apoplastic production of reactive oxygen species.     

Split luciferase complementation assay to detect regulated protein-protein interactions in rice protoplasts in a large-scale format

Background

The rice interactome, in which a network of protein-protein interactions has been elucidated in rice, is a useful resource to identify functional modules of rice signal transduction pathways. Protein-protein interactions occur in cells in two ways, constitutive and regulative. While a yeast-based high-throughput method has been widely used to identify the constitutive interactions, a method to detect the regulated interactions is rarely developed for a large-scale analysis.

Results

A split luciferase complementation assay was applied to detect the regulated interactions in rice. A transformation method of rice protoplasts in a 96-well plate was first established for a large-scale analysis. In addition, an antibody that specifically recognizes a carboxyl-terminal fragment of Renilla luciferase was newly developed. A pair of antibodies that recognize amino- and carboxyl- terminal fragments of Renilla luciferase, respectively, was then used to monitor quality and quantity of interacting recombinant-proteins accumulated in the cells. For a proof-of-concept, the method was applied to detect the gibberellin-dependent interaction between GIBBERELLIN INSENSITIVE DWARF1 and SLENDER RICE 1.

Conclusions

A method to detect regulated protein-protein interactions was developed towards establishment of the rice interactome.     

Protective Effect of Vitamin E against Diabetes-Induced Oxidized LDL and Aorta Cell Wall Proliferation in Rat

Background:

Hyperlipidemia and oxidized-low-density lipoproteins (Ox-LDL) are important independent cardiovascular risk factors that have been shown to stimulate vascular smooth muscle cell (VSMC) proliferation. The purpose of the present study was to investigate the effect of vitamin E on Ox-LDL, lipid profile, C-reactive protein (CRP), and VSMC proliferation of rat aorta.

Methods:

Male Wistar rats (n = 32) were divided into four groups namely: sham (SH), control (C), non-treated diabetic, and vitamin E-treated diabetic (VETD) groups. Ox-LDL, lipid profile, CRP and VSMC proliferation of aorta were measured after 42 days.

Results:

The results revealed that along with a significant increase in VSMC proliferation, the amount of CRP, Ox-LDL, and lipid profiles in diabetic rats. VSMC proliferation was significantly ameliorated, and elevated CRP, Ox-LDL, and lipid profiles were also restored to those of shams in VETD.

Conclusions:

These findings strongly support the idea that diabetes induces Ox-LDL-mediated oxidative stress and VSMC proliferation in aorta of rat and imply that vitamin E has a strong protective effect as an antioxidant. Key Words: Ox-LDL, Vitamin E, Diabetes, VSMC proliferation     

Heat Shock Proteins Enriched-Promastigotes of Leishmania major Inducing Th2 Immune Response in BALB/c Mice

Background

Heat shock proteins (HSP) are highly conserved molecules with many immunological functions. They are highly immunogenic with important role in cancer immunotherapy and in vaccine development against infectious diseases. As adjuvant, HSP can augment the immunogenicity of weak antigens and can stimulate antigen presenting cells. Although vaccines have been successful for many infectious diseases, progress in leishmaniasis has not been achieved. In this report, the protective effect of HSP-enriched soluble leishmania antigen (SLA) was determined.

Methods

BALB/c mice were immunized 3× with HSP-enriched SLA and SLA alone and 10 days after final boost. They were infected with 10⁶ stationary phase promastigote of Leishmania major and immunological responses were followed until nine weeks.

Results

No significant differences were observed in lymphocyte proliferation, footpad swelling, parasite burden, nitric oxide or IL-12 cytokine between HSP-enriched or SLA groups. Although the levels of IFN-γ, IL-4, TGF-β, IgG1 and IgG2b were increased in both groups, IFN-γ was significantly higher in SLA group and IgG2a in HSP-enriched SLA.

Conclusion

These results indicate that HSP direct the immune system towards Th2 pattern and does not have protective role in L. major infection. Key Words: Leishmaniasis, Heat shock proteins (HSP), Adjuvant     

Effect of Human Ovarian Tissue Vitrification/Warming on the Expression of Genes Related to Folliculogenesis

Background:

Ovarian tissue cryopreservation is an alternative strategy to preserve the fertility of women predicted to undergo premature ovarian failure. This study was designed to evaluate the expression of folliculogenesis-related genes, including factor in the germline alpha (FIGLA), growth differentiation factor-9 (GDF-9), follicle-stimulating hormone receptor (FSHR), and KIT LIGAND after vitrification/warming of human ovarian tissue.

Methods:

Human ovarian tissue samples were collected from five transsexual women. In the laboratory, the ovarian medullary part was removed by a surgical blade, and the cortical tissue was cut into small pieces. Some pieces were vitrified and warmed and the others were considered as non-vitrified group (control). Follicular normality was assessed with morphological observation by a light microscope, and the expression of FIGLA, KIT LIGAND, GDF-9,, and FSHR genes was examined using real-time RT-PCR in both the vitrified and non-vitrified groups.

Results:

Overall, 85% of the follicles preserved their normal morphologic feature after warming. The percentage of normal follicles and the expression of FIGLA, KIT LIGAND, GDF-9, and FSHR genes were similar in both vitrified and non-vitrified groups (P > 0.05).

Conclusion:

Vitrification/warming of human ovarian tissue had no remarkable effect on the expression of folliculogenesis-related genes. Key Words: Vitrification, Gene expression, Humans     

An Enterovirus-Like RNA Construct for Colon Cancer Suicide Gene Therapy

Background:

In gene therapy, the use of RNA molecules as therapeutic agents has shown advantages over plasmid DNA, including higher levels of safety. However, transient nature of RNA has been a major obstacle in application of RNA in gene therapy.

Methods:

Here, we used the internal ribosomal entry site of encephalomyocarditis virus and the 3’ non-translated region of Poliovirus to design an enterovirus-like RNA for the expression of a reporter gene (enhanced green fluorescent protein) and a suicide gene (thymidine kinase of herpes simplex virus). The expression of these genes was evaluated by flow cytometry and cytotoxicity assay in human colorectal adenocarcinoma cell line (SW480). We then armed RNA molecules with a target sequence for hsa-miR-143 to regulate their expression by microRNA (miRNA) mimics.

Results:

The results showed effective expression of both genes by Entrovirus-like RNA constructs. The data also showed that the restoration of hsa-miR-143 expression in SW480 leads to a significant translation repression of the introduced reporter and suicide genes.

Conclusion:

Collectively, our data suggest the potential use of Entrovirus-like RNA molecules in suicide gene therapy. Additionally, as a consequence of the possible downregulated miRNA expression in cancerous tissues, a decreased expression of gene therapy constructs armed with target sequences for such miRNA in cancer tissue is expected.Key Words: Thymidine kinase, Polio 3’NCR, miR-143     

Molecular Genetic Analysis of the Variable Number of Tandem-Repeat Alleles at the Phenylalanine Hydroxylase Gene in Iranian Azeri Turkish Population

Background:

The variable numbers of tandem-repeat (VNTR) alleles at the phenylalanine hydroxylase (PAH) gene have been used in carrier detection and prenatal diagnosis in phenylketonuria families. This study was carried out to analyze VNTR alleles at the PAH gene in Iranian Azeri Turkish population.

Methods:

In this study, 200 alleles from general population were studied by PCR.

Results:

The frequencies of VNTR alleles were 45%, 46%, 2%, 3%, 1%, and 3% in studied group regarding 3, 8, 9, 11, 12, and 13 repeat copies, respectively. Statistically significant differences were not found between expected and observed frequencies of VNTR genotypes (P > 0.05).

Conclusions:

VNTR alleles with three and eight repeats were frequent, and the VNTR alleles with 13 repeats showed 3% frequency in the tested group. This study is the first report on tested population genetic structure using VNTR alleles at the PAH gene. Key Words: Phenylalanine hydroxylase, Population genetics, Variable numbers of tandem-repeat     

Protective Role of Oleuropein against Acute Deltamethrin-Induced Neurotoxicity in Rat Brain

Background:

Deltamethrin (DM) is a synthetic pyrethroid insecticide that can elicit neurotoxicity, leading to apoptosis. There is accumulating evidence that oleuropein (OE) has anti-apoptotic effect. The purpose of this study was to determine the anti-apoptotic effect of OE pretreatment in the neuronal cells of cerebral cortex.

Methods:

Rats were randomly divided into four groups each containing five rats: DM-treated group (12.5 mg/kg, a single dose), OE-treated group (20 mg/kg per day), DM + OE-treated group, and vehicle group. Sections of the brain were obtained 24 hours after DM injection and studied for histopathological and immunohistochemistry assessment.

Results:

The histopathological assessments showed lesser characteristics of neural degeneration in DM + OE group compared with DM group. Greater Bcl-2 and attenuated Bax expression could be detected in the DM + OE treated-mice compared with DM group.

Conclusion:

The results suggested that DM-induced neurotoxicity can be subsided by OE.Key Words: Deltamethrin, Oleuropein, Apoptosis     

Progressive drought alters architectural and anatomical traits of rice roots

Background

Root architectural and anatomical phenotypes are important for adaptation to drought. Many rice-growing regions face increasing water scarcity. This study describes drought responses of 11 Egyptian rice cultivars with emphasis on plastic root responses that may enhance drought adaptation.

Results

Eleven Egyptian rice cultivars were phenotyped for root architectural and anatomical traits after 6 weeks growth in soil mesocosms under well-watered conditions. Four of these cultivars were more intensively phenotyped under progressive drought stress in mesocosms, using a system where more moisture was available at depth than near the surface. In response to drought stress, all cultivars significantly reduced nodal root number while increasing large lateral root branching density and total lateral root length in the deepest portions of the mesocosm, where moisture was available. Nodal root cross-sectional area, but not stele area, was reduced by drought stress, especially in the basal segments of the root, and the number of late metaxylem vessels was reduced in only one cultivar. Alterations in deposition of lignin were detected by UV illumination from laser ablation tomography, enhanced by digital staining, and confirmed with standard histochemical methods. In well-watered plants, the sclerenchyma and endodermis were heavily lignified, and lignin was also visible throughout the epidermis and cortex. Under drought stress, very little lignin was detected in the outer cell layers and none in the cortex of nodal roots, but lignin deposition was enhanced in the stele. Root anatomical phenes, including cross-section area and metaxylem vessel number and lignin deposition varied dramatically along large lateral root axes under drought stress, with increasing diameter and less lignification of the stele in successive samples taken from the base to the root apex.

Conclusions

Root architectural and anatomical traits varied significantly among a set of Egyptian cultivars. Most traits were plastic, i.e. changed significantly with drought treatment, and, in many cases, plasticity was cultivar-dependent. These phenotypic alterations may function to enhance water uptake efficiency. Increased large lateral root branching in the deep soil should maintain water acquisition, while water transport during drought should be secured with a more extensively lignified stele.

     

Role of GABAB Receptor and L-Arg in GABA-Induced Vasorelaxation in Non-diabetic and Streptozotocin-Induced Diabetic Rat Vessels

Background:

Hypertension is considered an independent risk factor for cardiovascular mortality in diabetic patients. The present study was designed to determine the role of gamma amino butyric acid B (GABA_B) receptor and L-arginine (L-Arg) in GABA-induced vasorelaxation in normal and streptozotocin-induced diabetic rat vessels.

Methods:

Diabetes was induced by a single i.p. injection of streptozotocin (STZ, 60 mg/kg). Eight weeks later, superior mesenteric arteries of all groups were isolated and perfused according to the McGregor method.

Results:

Baseline perfusion pressure of STZ diabetic rats was significantly higher than non-diabetic rats in both intact and denuded endothelium. In the presence of faclofen, a selective GABA_B receptor blocker, GABA-induced relaxation in intact and denuded endothelium mesenteric beds of STZ diabetic rats was suppressed, but this response in non-diabetic rats was not suppressed. Our results showed that in the presence of L-Arg, a nitric oxide precursor, GABA induced vasorelaxation in both diabetic and non-diabetic vessels.

Conclusion:

From the results of this study, it may be concluded that the vasorelaxatory effect of GABA in diabetic vessel is mediated by the GABA_B receptor and nitric oxide, but it seems that in non-diabetic vessel GABA_B receptor does not play any role in GABA-induced vasorelaxation, but nitric oxide induced GABA relaxation in non-diabetic vessel. Key Words: Gamma amino butyric acid (GABA), Diabetes, GABA_B receptor     

Genetic interaction between rice PLASTOCHRON genes and the gibberellin pathway in leaf development

Background

The rice PLASTOCHRON (PLA) genes PLA1 and PLA2 regulate leaf maturation and the temporal pattern of leaf initiation. Although the function of PLA genes in the leaf initiation process has been analyzed, little is known about how they affect leaf growth. Previously, we suggested that PLA1 and PLA2 function downstream of the gibberellin (GA) signal transduction pathway. In the present study, we examined the phenotype of a double mutant of pla and slender rice 1 (slr1), which is a constitutive GA response mutant. By analyzing these double mutants, we discuss the relationship between PLA-related and GA-dependent pathways and the possible function of PLA genes in leaf growth.

Findings

Single slr1 and pla mutants exhibited elongated and dwarf phenotypes in the vegetative stage, respectively. The stature and leaf size of the pla1/slr1 and pla2/slr1 double mutants were intermediate between those of the pla and slr1 single mutants. However, the effects of slr1 on leaf elongation were markedly suppressed in the pla1 and pla2 mutant backgrounds. On the other hand, the change in cell length in the double mutants was almost the same as that in the single mutants. An expression analysis of genes involved in GA biosynthesis and catabolism indicated that feedback regulation functioned normally in the pla/slr1 double mutants.

Conclusions

Our genetic results confirm that PLA genes regulate leaf growth downstream of the GA pathway. Our findings also suggest that PLA1 and PLA2 are partly required for GA-dependent leaf elongation, mainly by affecting cellular proliferation.     

Is Bax/Bcl-2 Ratio Considered as a Prognostic Marker with Age and Tumor Location in Colorectal Cancer?

Background:

Bax and Bcl-2 are the major members of Bcl-2 family whose play a key role in tumor progression or inhibition of intrinsic apoptotic pathway triggered by mitochondrial dysfunction. Therefore, the balance between pro- and anti-apoptotic members of this family can determine the cellular fate.

Methods:

In this study, the relative level of mRNA expression of Bax and Bcl-2 genes was determined using RNA extraction, cDNA synthesis and RT-qPCR technique from 22 tumoral tissues and adjacent non-tumoral tissues from adenocarcinoma colorectal cancer.

Results:

The potential prognostic and predictive significance of Bax and Bcl-2 gene expression and Bax/Bcl-2 ratio were demonstrated in colorectal cancer. The significant correlation between qPCR data and different clinicopathologic parameters of colorectal carcinoma, including age, gender, tumor size, tumor stage, tumor location, and tumor differentiation was also examined. Interestingly, no significant correlation was seen between Bax and Bcl-2 expressions and clinicopathological parameters of colorectal cancer. However, Bax/Bcl-2 ratio was statistically correlated with age and tumor location. Patients with age above 50 showed decreased levels of Bax/Bcl-2 ratio. Moreover, the Bax/Bcl-2 ratio was significantly lower in tumors resected from colon compared to sigmoid colon, rectosigmoid and rectum tumors.

Conclusion:

This study indicates a significant correlation between age and tumor location with Bax/Bcl-2 expression ratio, suggesting predictive value as a potential molecular marker of colorectal cancer.Key Words: Colorectal cancer, Bax/Bcl-2 ratio, Bax expression, Bcl-2 expression