Cloning and validation of novel miRNA from basmati rice indicates cross talk between abiotic and biotic stresses

Most of the physiological processes are controlled by the small RNAs in several organisms including plants. A huge database exists on one type of small RNA, i.e., microRNAs (miRs) identified from diverse species. However, the processes of data-mining of miRs in most of the species are still incomplete. Rice feeds the hungry trillions and hence understanding its developmental processes as well as its stress biology, which might be largely controlled by the small RNA pathways, is certainly a worthwhile task. Here, we report the cloning and identification of ~40 new putative miRs from local basmati rice variety in accordance to the annotation suggested by Meyers et al. (Plant Cell 20:3186–3190, 2008). About 23 sequences were derived from rice exposed to salt stress while 18 were derived from rice infected with tungro virus. A few of these putative miRs were common to both. Our data showed that at least two of these miRs were up-regulated in response to both abiotic and biotic stresses. The miR target predictions indicate that most of the putative miRs target specific metabolic processes. The up-regulation of similar miRs in response to two entirely different types of stresses suggests a converging functional role of miRs in managing various stresses. Our findings suggest that more rice miRs need to be identified and a thorough understanding of the function of such miRs will help unravel the mysteries of rice stress biology.     

Molecular cross talk between epithelial cells and pathogenic microorganisms

The conference brought together epithelial cell biologists and molecular microbiologists and emphasized that these seemingly diverse disciplines are intricately intertwined. The model systems discussed throughout the meeting emphasized the novel approaches available to address key issues and begin to understand the molecular details of responses triggered at the microbial-epithelial interface. For example, co-crystallization of native ligand-receptor complexes as well as biologically or chemically altered forms of these complexes will allow fine details of receptor-ligand interactions to be determined. This approach is critical in development of new generation antimicrobial agents. Furthermore, transfection techniques that allow receptor expression in model epithelia, development of representative animal model systems, and development of transgenic mouse strains will aid in dissecting microbial-epithelial interactions and will provide further advances in studies on pathogenesis and tissue and host tropism. We are only beginning to uncover the nature of the bidirectional regulatory signals that occur between microbes and hosts. We know little about how these signals relate to the disease state, to microbial virulence, or to immune function. Clearly the cross talk between cell biologists and microbiologists is an important step in unraveling the events occurring between microbes and eukaryotic cells.     

The Arabidopsis mutant alh1 illustrates a cross talk between ethylene and auxin

Ethylene or its precursor 1-aminocyclopropane-1-carboxylic acid (ACC) can stimulate hypocotyl elongation in light-grown Arabidopsis seedlings. A mutant, designated ACC-related long hypocotyl 1 (alh1), that displayed a long hypocotyl in the light in the absence of the hormone was characterized. Etiolated alh1 seedlings overproduced ethylene and had an exaggerated apical hook and a thicker hypocotyl, although no difference in hypocotyl length was observed when compared with wild type. Alh1 plants were less sensitive to ethylene, as reflected by reduction of ACC-mediated inhibition of hypocotyl growth in the dark and delay in flowering and leaf senescence. Alh1 also had an altered response to auxin, whereas auxin levels in whole alh1 seedlings remained unaffected. In contrast to wild type, alh1 seedlings showed a limited hypocotyl elongation when treated with indole-3-acetic acid. Alh1 roots had a faster response to gravity. Furthermore, the hypocotyl elongation of alh1 and of ACC-treated wild type was reverted by auxin transport inhibitors. In addition, auxin up-regulated genes were ectopically expressed in hypocotyls upon ACC treatment, suggesting that the ethylene response is mediated by auxins. Together, these data indicate that alh1 is altered in the cross talk between ethylene and auxins, probably at the level of auxin transport.     

The cross talk between protein kinase A- and RhoA-mediated signaling in cancer cells

The cross talk between cyclic adenosine monophosphate (cAMP)/protein kinase A (PKA) and RhoA-mediated signal transductions and the effect of this cross talk on biologic features of human prostate and gastric cancer cells were investigated. In the human gastric cancer cell line, SGC-7901, lysophosphatidic acid (LPA) increased RhoA activity in a dose-dependent manner. The cellular permeable cAMP analog, 8-chlorophenylthio-cAMP (CPT-cAMP), inhibited the LPA-induced RhoA activation and caused phosphorylation of RhoA at serine(188). Immunofluorescence microscopy, Western blotting, and green fluorescent protein (GFP)-tagged RhoA location assay in live cells revealed that RhoA was distributed in both the cytoplasm and nucleus of SGC-7901 cells. Treatment with LPA and/or CPT-cAMP did not induce obvious translocation of RhoA in the cells. The LPA treatment caused formation of F-actin in SGC-7901 cells, and CPT-cAMP inhibited the formation. In a modified Boyden chamber assay, LPA stimulated the migration of SGC-7901 cells, and CPT-cAMP dose-dependently inhibited the stimulating effect of LPA. In soft agar assay, LPA stimulated early proliferation of SGC-7901 cells, and CPT-cAMP significantly inhibited the growth of LPA-stimulated cells. In the prostate cancer cell line, PC-3, LPA caused morphologic changes from polygonal to round, and transfection with plasmid DNA encoding constitutively active RhoA(63L) caused a similar change. Treatment with CPT-cAMP inhibited the changes in both cases. However, in PC-3 cells transfected with a plasmid encoding mutant RhoA188A, LPA induced rounding, but CPT-cAMP could not prevent the change. Results of this experiment indicated that cAMP/PKA inhibited RhoA activation, and serine188 phosphorylation on RhoA was necessary for PKA to exert its inhibitory effect on RhoA activation. The cross talk between cAMP/PKA and RhoA-mediated signal transductions had significant affect on biologic features of gastric and prostate cancer cells, such as morphologic and cytoskeletal change, migration, and anchorage-independent growth. The results may be helpful in implementing novel therapeutic strategies for invasive and metastatic prostate and gastric cancers.     

Molecular cross talk between Toxoplasma gondii and the host immune system

Toxoplasma gondii is an intracellular parasite that frequently infects a large spectrum of warm-blooded animals. This parasite induces abortion and establishes both chronic and silent infections, particularly in the brain. The chronic infection is therefore a permanent threat for the host in cases of immunosuppression. Parasite penetration into the host activates a strong anti-parasite immune response, but is also used by the parasite to chronically persist. In the present paper, we discuss the data obtained in the laboratory of John Boothroyd that reports the molecular cross talk between the parasite rhoptry proteins and the host cell. During host cell invasion, rhoptries participate to the constitution of the mobile junction that drives the parasite into the host cell, while building the parasitophorus vacuole in which the parasite grows. Some soluble rhoptries, such as ROP16, are shed into the cytoplasm, and then reach the nucleus where they can eventually impact different signaling pathways such as STAT3/6, key molecules in the immune response establishment.     

A cross talk between codon usage bias in human oncogenes

Background: Oncogenes are the genes that have the potential to induce cancer. The extent and origin of codon usage bias is an important indicator of the forces shaping genome evolution in living organisms. Results: We observed moderate correlations between gene expression as measured by CAI and GC content at any codon site. The findings of our results showed that there is a significant positive correlation (Spearman''s r= 0.45, P<0.01) between GC content at first and second codon position with that of third codon position. Further, striking negative correlation (r = -0.771, P < 0.01) between ENC with the GC3s values of each gene and positive correlation (r=0.644, P<0.01) in between CAI and ENC was also observed. Conclusions: The mutation pressure is the major determining factor in shaping the codon usage pattern of oncogenes rather than natural selection since its effects are present at all codon positions. The results revealed that codon usage bias determines the level of oncogene expression in human. Highly expressed oncogenes had rich GC contents with high degree of codon usage bias.     

Prostanoid signal integration and cross talk

The enzymatic machinery for the production of prostanoids and the receptors responsible for detecting their presence are widely distributed in the body. One pair of prostanoids, prostacyclin and thromboxane A(2), are particularly important in the control of haemodynamics and haemostasis. Prostacyclin achieves its antiplatelet effect by acting as a physiological antagonist, but displays some selectivity towards thromboxane A(2)-mediated platelet activation, possibly by virtue of the inability of thromboxane A(2) receptors to couple directly to G(i) proteins, and because platelet-derived endoperoxides can act as substrates for prostacyclin synthesis in endothelial cells. At low concentrations, prostaglandin E(2) can synergize with thromboxane A(2) by acting on the EP(3) subtype of prostaglandin E(2) receptor, resulting in opposition to the protective function of prostacyclin. In contrast, high concentrations of prostaglandin E(2) act on the prostacyclin receptor, and possibly the prostaglandin D(2) receptor, to turn off platelet activation. Integration of prostanoid signalling in the vascular system is similarly complex, and interpretation of data is further complicated by the regional distribution of prostanoid receptors in different vascular beds, and the poor selectivity of agonists and antagonists.     

The R-Ras GTPase mediates cross talk between estrogen and insulin signaling in breast cancer cells

The signaling cascades activated by insulin and IGF-1 contribute to the control of multiple cellular functions, including glucose metabolism and cell proliferation. In most cases these effects are mediated, at least in part, by insulin receptor substrates (IRS), one of which is insulin receptor substrate 1 (IRS-1). R-Ras is a member of the Ras family of GTPases and is involved in a variety of biological processes, including integrin activation, cell migration, and control of cell proliferation. Here we demonstrate that both R-Ras and BCAR3, a regulator of R-Ras activity that has been implicated in breast cancer, regulate the level of IRS-1 protein in estrogen-dependent MCF-7 and ZR75 breast cancer cells. In particular, expression of a constitutively activated R-Ras mutant, R-Ras38V, or of BCAR3 accelerates the degradation of IRS-1, leading to the impairment of signaling through insulin but not epidermal growth factor receptors. Moreover, knockdown of endogenous R-Ras levels in MCF-7 cells inhibits IRS-1 degradation induced by estrogen signaling blockade but not by long-term insulin treatment. Consistent with these results, both R-Ras38V expression and estrogen signaling blockade lead to the degradation of IRS-1, at least in part, through calpain activity. These findings show that R-Ras activity mediates inhibition of insulin signaling associated with suppression of estrogen action, implicating this GTPase in a growth-inhibitory mechanism associated with antiestrogen treatment of breast cancer.     

Response and relation of allantoin production in different rice cultivars to competing barnyardgrass

The production of secondary metabolites and biomass of plants may be altered by coexistence and competition. Rice has coexisted with barnyardgrass in paddy systems for centuries and represents a model system for understanding plant–plant interactions. Despite increasing knowledge of allelochemicals produced and released by rice involved in coexistence of these two species, relatively little is known about the role and production of beneficial chemicals of rice in response to competing barnyardgrass. The purpose of this study was to quantify the growth-stimulating allantoin (5-ureidohydantoin) and its effect on barnyardgrass growth in a rice–barnyardgrass system. In this system, rice produced and released allantoin but barnyardgrass did not. The production of allantoin by rice responded to competition from barnyardgrass, and its concentration varied among rice cultivars tested. At 1:1 barnyardgrass and rice mixture proportion, allantoin concentration in allelopathic cultivars was obviously lowered by competing barnyardgrass, while no significant variation of allantoin concentration was observed in non-allelopathic cultivars. Barnyardgrass biomass was reduced in mixed-culture with rice cultivars, in particular, allelopathic cultivars. There was a positive relationship between allantoin concentration in rice cultivars and barnyardgrass biomass. Furthermore, allantoin stimulated the growth of barnyardgrass once released from rice or added to soil. The results suggest that rice plants of allelopathic cultivars appear to be able to detect the presence of competing barnyardgrass and respond by decreasing production of growth-stimulating allantoin, regulating the growth of barnyardgrass. In this manner, given rice cultivars may alleviate the competition of barnyardgrass and provide greater benefit to their own growth.     

The functional cross talk between cancer cells and cancer associated fibroblasts from a cancer mechanics perspective

The function of biological tissues in health and disease is regulated at cellular level and is highly influenced by the physical microenvironment, through the interaction of forces between cells and ECM, which are perceived through mechanosensing pathways. In cancer, both chemical and physical signaling cascades and their interactions are involved during cell-cell and cell-ECM communications to meet requirements of tumor growth. Among stroma cells, cancer associated fibroblasts (CAFs) play key role in tumor growth and pave the way for cancer cells to initiate metastasis and invasion to other tissues, and without recruitment of CAFs, the process of cancer invasion is dysfunctional. This is through an intense chemical and physical cross talks with tumor cells, and interactive remodeling of ECM. During such interaction CAFs apply traction forces and depending on the mechanical properties, deform ECM and in return receive physical signals from the micromechanical environment. Such interaction leads to ECM remodeling by manipulating ECM structure and its mechanical properties. The results are in form of deposition of extra fibers, stiffening, rearrangement and reorganization of fibrous structure, and degradation which are due to a complex secretion and expression of different markers triggered by mechanosensing of tumor cells, specially CAFs. Such events define cancer progress and invasion of cancer cells.A systemic knowledge of chemical and physical factors provides a holistic view of how cancer process and enhances the current treatment methods to provide more diversity among targets that involves tumor cells and ECM structure.     

Separation of allelopathy from resource competition using rice/barnyardgrass mixed-cultures

Plant-plant interference is the combined effect of allelopathy, resource competition, and many other factors. Separating allelopathy from resource competition is almost impossible in natural systems but it is important to evaluate the relative contribution of each of the two mechanisms on plant interference. Research on allelopathy in natural and cultivated plant communities has been hindered in the absence of a reliable method that can separate allelopathic effect from resource competition. In this paper, the interactions between allelopathic rice accession PI312777, non-allelopathic rice accession Lemont and barnyardgrass were explored respectively by using a target (rice)-neighbor (barnyardgrass) mixed-culture in hydroponic system. The relative competitive intensity (RCI), the relative neighbor effect (RNE) and the competitive ratio (CR) were used to quantify the intensity of competition between each of the two different potentially allelopathic rice accessions and barnyardgrass. Use of hydroponic culture system enabled us to exclude any uncontrolled factors that might operate in the soil and we were able to separate allelopathy from resource competition between each rice accession and barnyardgrass. The RCI and RNE values showed that the plant-plant interaction was positive (facilitation) for PI312777 but that was negative (competition) for Lemont and barnyardgrass in rice/barnyardgrass mixed-cultures. The CR values showed that one PI312777 plant was more competitive than 2 barnyardgrass plants. The allelopathic effects of PI312777 were much more intense than the resource competition in rice/barnyardgrass mixed cultures. The reverse was true for Lemont. These results demonstrate that the allelopathic effect of PI312777 was predominant in rice/barnyardgrass mixed-cultures. The most significant result of our study is the discovery of an experimental design, target-neighbor mixed-culture in combination with competition indices, can successfully separate allelopathic effects from competition.     

Organ cross talk modulates pelvic pain

Interstitial cystitis (IC) is a chronic bladder inflammatory disease of unknown etiology that is often regarded as a neurogenic cystitis. IC is associated with urothelial lesions, voiding dysfunction, and pain in the pelvic/perineal area, and diet can exacerbate IC symptoms. In this study, we used a murine neurogenic cystitis model to investigate the development of pelvic pain behavior. Neurogenic cystitis was induced by the injection of Bartha's strain of pseudorabies virus (PRV) into the abductor caudalis dorsalis tail base muscle of female C57BL/6J mice. Infectious PRV virions were isolated only from the spinal cord, confirming the centrally mediated nature of this neurogenic cystitis model. Pelvic pain was assessed using von Frey filament stimulation to the pelvic region, and mice infected with PRV developed progressive pelvic pain. Pelvic pain was alleviated by 2% lidocaine instillation into either the bladder or the colon but not following lidocaine instillation into the uterus. The bladders of PRV-infected mice showed markers of inflammation and increased vascular permeability compared with controls. In contrast, colon histology was normal and vascular permeability was unchanged, suggesting that development of pelvic pain was due only to bladder inflammation. Bladder-induced pelvic pain was also exacerbated by colonic administration of a subthreshold dose of capsaicin. These data indicate organ cross talk in pelvic pain and modulation of pain responses by visceral inputs distinct from the inflamed site. Furthermore, these data suggest a mechanism by which dietary modification benefits pelvic pain symptoms.     

The mitosis-to-interphase transition is coordinated by cross talk between the SIN and MOR pathways in Schizosaccharomyces pombe

The mechanisms that regulate cytoskeletal remodeling during the transition between mitosis and interphase are poorly understood. In fission yeast the MOR pathway promotes actin polarization to cell tips in interphase, whereas the SIN signaling pathway drives actomyosin ring assembly and cytokinesis. We show that the SIN inhibits MOR signaling in mitosis by interfering with Nak1 kinase-mediated activation of the most downstream MOR component, the NDR family kinase Orb6. Inactivation of the MOR may be a key function of the SIN because attenuation of MOR signaling rescued the cytokinetic defects of SIN mutants and allowed weak SIN signaling to trigger ectopic cytokinesis. Furthermore, failure to inhibit the MOR is toxic when the cell division apparatus is compromised. Together, our results reveal a mutually antagonistic relationship between the SIN and MOR pathways, which is important for completion of cytokinesis and coordination of cytoskeletal remodeling at the mitosis-to-interphase transition.     

The cell pole: the site of cross talk between the DNA uptake and genetic recombination machinery

Natural transformation is a programmed mechanism characterized by binding of free double-stranded (ds) DNA from the environment to the cell pole in rod-shaped bacteria. In Bacillus subtilis some competence proteins, which process the dsDNA and translocate single-stranded (ss) DNA into the cytosol, recruit a set of recombination proteins mainly to one of the cell poles. A subset of single-stranded binding proteins, working as “guardians”, protects ssDNA from degradation and limit the RecA recombinase loading. Then, the “mediators” overcome the inhibitory role of guardians, and recruit RecA onto ssDNA. A RecA·ssDNA filament searches for homology on the chromosome and, in a process that is controlled by “modulators”, catalyzes strand invasion with the generation of a displacement loop (D-loop). A D-loop resolvase or “resolver” cleaves this intermediate, limited DNA replication restores missing information and a DNA ligase seals the DNA ends. However, if any step fails, the “rescuers” will repair the broken end to rescue chromosomal transformation. If the ssDNA does not share homology with resident DNA, but it contains information for autonomous replication, guardian and mediator proteins catalyze plasmid establishment after inhibition of RecA. DNA replication and ligation reconstitute the molecule (plasmid transformation). In this review, the interacting network that leads to a cross talk between proteins of the uptake and genetic recombination machinery will be placed into prospective.     

Study of cross talk between phosphatases and OGA on a ZO-3-derived peptide

Amino Acids - O-GlcNAcylation, like phosphorylation, is a dynamic and rapid posttranslational modification which regulates many cellular processes. Phosphorylation on tyrosine and O-GlcNAcylation...     

水稻移栽密度和早期水管理对无芒稗生态控制效果的影响

在 5 0株·m-2 无芒稗的干扰下 ,杂交水稻Ⅱ优 2 0 70移栽密度 1 9 8cm× 2 6 4cm处理对无芒稗的生态控制效果显著高于较稀密度的 1 9 8cm× 4 6 2cm ,无芒稗颖果减少 71 %。移栽密度 1 9 8cm× 2 6 4cm保证了较高的水稻有效穗和千粒重 ,比移栽密度 1 9 8cm× 4 6 2cm的水稻增产 1 3 3%。早期深水灌溉能有效控制萌芽期的无芒稗 ,但不能防治 3叶龄的无芒稗