Silicon enhances suberization and lignification in roots of rice (Oryza sativa)

The beneficial element silicon (Si) may affect radial oxygen loss (ROL) of rice roots depending on suberization of the exodermis and lignification of sclerenchyma. Thus, the effect of Si nutrition on the oxidation power of rice roots, suberization and lignification was examined. In addition, Si-induced alterations of the transcript levels of 265 genes related to suberin and lignin synthesis were studied by custom-made microarray and quantitative Real Time-PCR. Without Si supply, the oxidation zone of 12 cm long adventitious roots extended along the entire root length but with Si supply the oxidation zone was restricted to 5 cm behind the root tip. This pattern coincided with enhanced suberization of the exodermis and lignification of sclerenchyma by Si supply. Suberization of the exodermis started, with and without Si supply, at 4–5 cm and 8–9 cm distance from the root tip (drt), respectively. Si significantly increased transcript abundance of 12 genes, while two genes had a reduced transcript level. A gene coding for a leucine-rich repeat protein exhibited a 25-fold higher transcript level with Si nutrition. Physiological, histochemical, and molecular-biological data showing that Si has an active impact on rice root anatomy and gene transcription is presented here

Expression of RHOGTPase regulators in human myometrium

<p>Abstract</p> <p>Background</p> <p>RHOGTPases play a significant role in modulating myometrial contractility in uterine smooth muscle. They are regulated by at least three families of proteins, RHO guanine nucleotide exchange factors (RHOGEFs), RHOGTPase-activating proteins (RHOGAPs) and RHO guanine nucleotide inhibitors (RHOGDIs). RHOGEFs activate RHOGTPases from the inactive GDP-bound to the active GTP-bound form. RHOGAPs deactivate RHOGTPases by accelerating the intrinsic GTPase activity of the RHOGTPases, converting them from the active to the inactive form. RHOGDIs bind to GDP-bound RHOGTPases and sequester them in the cytosol, thereby inhibiting their activity. Ezrin-Radixin-Moesin (ERM) proteins regulate the cortical actin cytoskeleton, and an ERM protein, moesin (MSN), is activated by and can also activate RHOGTPases.</p> <p>Methods</p> <p>We therefore investigated the expression of various RHOGEFs, RHOGAPs, a RHOGDI and MSN in human myometrium, by semi-quantitative reverse transcription PCR, real-time fluorescence RT-PCR, western blotting and immunofluorescence microscopy. Expression of these molecules was also examined in myometrial smooth muscle cells.</p> <p>Results</p> <p>ARHGEF1, ARHGEF11, ARHGEF12, ARHGAP5, ARHGAP24, ARHGDIA and MSN mRNA and protein expression was confirmed in human myometrium at term pregnancy, at labour and in the non-pregnant state. Furthermore, their expression was detected in myometrial smooth muscle cells. It was determined that ARHGAP24 mRNA expression significantly increased at labour in comparison to the non-labour state.</p> <p>Conclusion</p> <p>This study demonstrated for the first time the expression of the RHOGTPase regulators ARHGEF1, ARHGEF11, ARHGEF12, ARHGAP5, ARHGAP24, ARHGDIA and MSN in human myometrium, at term pregnancy, at labour, in the non-pregnant state and also in myometrial smooth muscle cells. ARHGAP24 mRNA expression significantly increased at labour in comparison to the non-labouring state. Further investigation of these molecules may enable us to further our knowledge of RHOGTPase regulation in human myometrium during pregnancy and labour.</p

Prevalence and correlates of alcohol dependence disorder among TB and HIV infected patients in Zambia.

OBJECTIVES: To determine the prevalence and correlates of alcohol dependence disorders in persons receiving treatment for HIV and Tuberculosis (TB) at 16 Primary Health Care centres (PHC) across Zambia. METHODS: 649 adult patients receiving treatment for HIV and/or TB at PHCs in Zambia (363 males, 286 females) were recruited between 1st December 2009 and 31st January 2010. Data on socio-demographic variables, clinical disease features (TB and HIV), and psychopathological status were collected. The Mini International Neuropsychiatric Interview (MINI) was used to diagnose alcohol dependence disorder. Correlates of alcohol dependence were analyzed for men only, due to low prevalence in women. Univariable and multivariable logistic regression models were used to estimate odds ratios (OR) and 95% confidence intervals (CI), using general estimating equations to allow for within-PHC clustering. RESULTS: The prevalence of alcohol dependence was 27.2% (95%CI: 17.7-39.5%) for men and 3.9% (95%CI: 1.4-0.1%) for women. Factors associated with alcohol dependence disorder in men included being single, divorced or widowed compared with married (adjusted OR = 1.47, 95%CI: 1.00-2.14) and being unemployed (adjusted OR=1.30, 95%CI: 1.01-1.67). The highest prevalence of alcohol dependence was among HIV-test unknown TB patients (34.7%), and lowest was among HIV positive patients on treatment but without TB (14.1%), although the difference was not statistically significant (p=0.38). CONCLUSIONS: Male TB/HIV patients in this population have high prevalence of alcohol dependence disorder, and prevalence differs by HIV/TB status. Further work is needed to explore interventions to reduce harmful drinking in this population

The Arabidopsis cytochrome P450 CYP86A1 encodes a fatty acid ω-hydroxylase involved in suberin monomer biosynthesis

The lipophilic biopolyester suberin forms important boundaries to protect the plant from its surrounding environment or to separate different tissues within the plant. In roots, suberin can be found in the cell walls of the endodermis and the hypodermis or periderm. Apoplastic barriers composed of suberin accomplish the challenge to restrict water and nutrient loss and prevent the invasion of pathogens. Despite the physiological importance of suberin and the knowledge of the suberin composition of many plants, very little is known about its biosynthesis and the genes involved. Here, a detailed analysis of the Arabidopsis aliphatic suberin in roots at different developmental stages is presented. This study demonstrates some variability in suberin amount and composition along the root axis and indicates the importance of ω-hydroxylation for suberin biosynthesis. Using reverse genetics, the cytochrome P450 fatty acid ω-hydroxylase CYP86A1 (At5g58860) has been identified as a key enzyme for aliphatic root suberin biosynthesis in Arabidopsis. The corresponding horst mutants show a substantial reduction in ω-hydroxyacids with a chain length <C20, demonstrating that CYP86A1 functions as a hydroxylase of root suberized tissue. Detailed expression studies revealed a strong root specificity and a localized expression in the root endodermis. Transgenic expression of CYP86A1 fused to GFP distributed CYP86A1 to the endoplasmic reticulum, indicating that suberin monomer biosynthesis takes place in this sub-cellular compartment before intermediates are exported in the apoplast

Molecular targets in the discovery and development of novel antimetastatic agents: current progress and future prospects

Tumour invasion and metastasis have been recognized as major causal factors in the morbidity and mortality among cancer patients. Many advances in the knowledge of cancer metastasis have yielded an impressive array of attractive drug targets, including enzymes, receptors and multiple signalling pathways. The present review summarizes the molecular pathogenesis of metastasis and the identification of novel molecular targets used in the discovery of antimetastatic agents. Several promising targets have been highlighted, including receptor tyrosine kinases, effector molecules involved in angiogenesis, matrix metalloproteinases (MMPs), urokinase plasminogen activator, adhesion molecules and their receptors, signalling pathways (e.g. phosphatidylinositol 3-kinase, phospholipase Cγ1, mitogen-activated protein kinases, c-Src kinase, c-Met kinases and heat shock protein. The discovery and development of potential novel therapeutics for each of the targets are also discussed in this review. Among these, the most promising agents that have shown remarkable clinical outcome are anti-angiogenic agents (e.g. bevacizumab). Newer agents, such as c-Met kinase inhibitors, are still undergoing preclinical studies and are yet to have their clinical efficacy proven. Some therapeutics, such as first-generation MMP inhibitors (MMPIs; e.g. marimastat) and more selective versions of them (e.g. prinomastat, tanomastat), have undergone clinical trials. Unfortunately, these drugs produced serious adverse effects that led to the premature termination of their development. In the future, third-generation MMPIs and inhibitors of signalling pathways and adhesion molecules could form valuable novel classes of drugs in the anticancer armamentarium to combat metastasis

Tumor interactions with soluble factors and the nervous system

In the genomic era of cancer research, the development of metastases has been attributed to mutations in the tumor that enable the cells to migrate. However, gene analyses revealed that primary tumors and metastases were in some cases genetically identical and the question was raised whether metastasis formation might be an inherent feature of certain tumor cells. In contradiction to this view, the last decade of cancer research has brought to light, that tumor cell migration, similar to leukocyte and fibroblast migration, is a highly regulated process. The nervous system plays an important role in this regulation, at least in two respects: firstly, neurotransmitters are known to regulate the migratory activity of tumor cells, and secondly, nerve fibers are used as routes for perineural invasion. We also summarize here the current knowledge on the innervation of tumors. Such a process might establish a neuro-neoplastic synapse, with the close interaction of tumor cells and nerve cells supporting metastasis formation

Leukocyte Tyrosine Kinase Functions in Pigment Cell Development

A fundamental problem in developmental biology concerns how multipotent precursors choose specific fates. Neural crest cells (NCCs) are multipotent, yet the mechanisms driving specific fate choices remain incompletely understood. Sox10 is required for specification of neural cells and melanocytes from NCCs. Like sox10 mutants, zebrafish shady mutants lack iridophores; we have proposed that sox10 and shady are required for iridophore specification from NCCs. We show using diverse approaches that shady encodes zebrafish leukocyte tyrosine kinase (Ltk). Cell transplantation studies show that Ltk acts cell-autonomously within the iridophore lineage. Consistent with this, ltk is expressed in a subset of NCCs, before becoming restricted to the iridophore lineage. Marker analysis reveals a primary defect in iridophore specification in ltk mutants. We saw no evidence for a fate-shift of neural crest cells into other pigment cell fates and some NCCs were subsequently lost by apoptosis. These features are also characteristic of the neural crest cell phenotype in sox10 mutants, leading us to examine iridophores in sox10 mutants. As expected, sox10 mutants largely lacked iridophore markers at late stages. In addition, sox10 mutants unexpectedly showed more ltk-expressing cells than wild-type siblings. These cells remained in a premigratory position and expressed sox10 but not the earliest neural crest markers and may represent multipotent, but partially-restricted, progenitors. In summary, we have discovered a novel signalling pathway in NCC development and demonstrate fate specification of iridophores as the first identified role for Ltk