Do plants adjust their sex allocation and secondary sexual morphology in response to their neighbours?

BACKGROUND AND AIMS: Changes in the sex allocation (i.e. in pollen versus seed production) of hermaphroditic plants often occur in response to the environment. In some homosporous ferns, gametophytes choose their gender in response to chemical cues sent by neighbours, such that spores develop as male gametophytes if they perceive a female or hermaphrodite nearby. Here it is considered whether a similar process might occur in the androdioecious angiosperm species Mercurialis annua, in which males co-occur with hermaphrodites; previous work on a Spanish population of M. annua found that individuals were more likely to develop as males at high density. METHODS: Using a novel approach to treat plants with leachate from pots containing males or hermaphrodites of M. annua, the hypothesis that individuals assess their mating opportunities, and adjust their sex expression accordingly, was tested through an exchange of chemical cues through the soil. KEY RESULTS: For the population under study, from Morocco, no evidence was found for soil-signal-dependent sex expression: neither sex ratios nor sex allocation differed among experimental treatments. CONCLUSIONS: The results imply either that the Moroccan population under study behaves differently from that previously studied in Spain (pointing to potential geographical variation in plasticity for sex expression), or that our method failed to capture the signals used by M. annua for adjustment of sex expression.

A repeated GGA motif is critical for the activity and stability of the riboregulator RsmY of Pseudomonas fluorescens.

The riboregulator RsmY of Pseudomonas fluorescens strain CHA0 is an example of small regulatory RNAs belonging to the global Rsm/Csr regulatory systems controlling diverse cellular processes such as glycogen accumulation, motility, or formation of extracellular products in various bacteria. By binding multiple molecules of the small regulatory protein RsmA, RsmY relieves the negative effect of RsmA on the translation of several target genes involved in the biocontrol properties of strain CHA0. RsmY and functionally related riboregulators have repeated GGA motifs predicted to be exposed in single-stranded regions, notably in the loops of hairpins. The secondary structure of RsmY was corroborated by in vivo cleavage with lead acetate. RsmY mutants lacking three or five (out of six) of the GGA motifs showed reduced ability to derepress the expression of target genes in vivo and failed to bind the RsmA protein efficiently in vitro. The absence of GGA motifs in RsmY mutants resulted in reduced abundance of these transcripts and in a shorter half-life (< or = 6 min as compared with 27 min for wild type RsmY). These results suggest that both the interaction of RsmY with RsmA and the stability of RsmY strongly depend on the GGA repeats and that the ability of RsmY to interact with small regulatory proteins such as RsmA may protect this RNA from degradation.

The gene for the ligand binding chain of the human interferon gamma receptor.

In order to characterize the gene encoding the ligand binding (1(st); alpha) chain of the human IFN-gamma receptor, two overlapping cosmid clones were analyzed. The gene spans over 25 kilobases (kb) of the genomic DNA and has seven exons. The extracellular domain is encoded by exons 1 to 5 and by part of exon 6. The transmembrane region is also encoded by exon 6. Exon 7 encodes the intracellular domain and the 3' untranslated portion. The gene was located on chromosome 6q23.1, as determined by in situ hybridization. The 4 kb region upstream (5') of the gene was sequenced and analyzed for promoter activity. No consensus-matching TATA or CAAT boxes in the 5' region were found. Potential binding sites for Sp1, AP-1, AP-2, and CREB nuclear factors were identified. Compatible with the presence of the Sp1/AP-2 sites and the lack of TATA box, S1-nuclease mapping experiments showed multiple transcription initiation sites. Promoter activity of the 5' flanking region was analyzed with two different reporter genes: the Escherichia coli chloramphenicol acetyltransferase and human growth hormone. The smallest 5' region of the gene that still had full promoter activity was 692 base pairs in length. In addition, we found sequences belonging to the oldest family of Alu repeats, 2 - 3 kb upstream of the gene, which could be useful for genetic studies.

Atenção pré-natal por enfermeiros na Zona Leste da cidade de São Paulo - Brasil

Com o objetivo de analisar o exercício das competências dos enfermeiros para a atenção pré-natal por meio da identificação das atividades que desempenham e sua frequência, bem como dos possíveis obstáculos que encontram, realizou-se estudo quantitativo, descritivo-exploratório, em 59 Unidades Básicas de Saúde da Zona Leste da cidade de São Paulo, de outubro de 2006 a dezembro de 2007. A amostra foi constituída de 131 enfermeiros. Os resultados mostraram que os enfermeiros não exercem as competências essenciais para a atenção qualificada ao pré-natal, devido às barreiras pessoais e institucionais com que se defrontam em seu trabalho. Conclui-se pela necessidade das estruturas públicas de saúde municipais revisarem suas políticas de modo a garantir a implementação das diretrizes do SUS no que se refere à melhoria da atenção à saúde materno-infantil, e à destinação de recursos humanos e financeiros nessa direção.

T-Cell Receptors Binding Orientation over Peptide/MHC Class I Is Driven by Long-Range Interactions.

Crystallographic data about T-Cell Receptor - peptide - major histocompatibility complex class I (TCRpMHC) interaction have revealed extremely diverse TCR binding modes triggering antigen recognition. Understanding the molecular basis that governs TCR orientation over pMHC is still a considerable challenge. We present a simplified rigid approach applied on all non-redundant TCRpMHC crystal structures available. The CHARMM force field in combination with the FACTS implicit solvation model is used to study the role of long-distance interactions between the TCR and pMHC. We demonstrate that the sum of the coulomb interactions and the electrostatic solvation energies is sufficient to identify two orientations corresponding to energetic minima at 0° and 180° from the native orientation. Interestingly, these results are shown to be robust upon small structural variations of the TCR such as changes induced by Molecular Dynamics simulations, suggesting that shape complementarity is not required to obtain a reliable signal. Accurate energy minima are also identified by confronting unbound TCR crystal structures to pMHC. Furthermore, we decompose the electrostatic energy into residue contributions to estimate their role in the overall orientation. Results show that most of the driving force leading to the formation of the complex is defined by CDR1,2/MHC interactions. This long-distance contribution appears to be independent from the binding process itself, since it is reliably identified without considering neither short-range energy terms nor CDR induced fit upon binding. Ultimately, we present an attempt to predict the TCR/pMHC binding mode for a TCR structure obtained by homology modeling. The simplicity of the approach and the absence of any fitted parameters make it also easily applicable to other types of macromolecular protein complexes.

Final Report, Secondary Road Fund Distribution Advisory Committee, 2002-2005

This report presents the findings and recommendations of the Secondary Road Fund Distribution Advisory Committee (SRFDAC) established by SF 2192 of the 2002 Iowa Acts.

Synthesis, binding affinity and SAR of new benzolactam derivatives as dopamine D3 receptor ligands

A series of new benzolactam derivatives was synthesized and the derivatives were evaluated for theiraffinities at the dopamine D1, D2, and D3 receptors. Some of these compounds showed high D2 and/orD3 affinity and selectivity over the D1 receptor. The SAR study of these compounds revealed structuralcharacteristics that decisively influenced their D2 and D3 affinities. Structural models of the complexesbetween some of the most representative compounds of this series and the D2 and D3 receptors wereobtained with the aim of rationalizing the observed experimental results. Moreover, selected compoundsshowed moderate binding affinity on 5-HT2A which could contribute to reducing the occurrence of extrapyramidalside effects as potential antipsychotics.

Multi-receptor binding profile of clozapine and olanzapine: a structural study based on the new beta (2) adrenergic receptor template

Schizophrenia is a devastating mental disorder that has a largeimpact on the quality of life for those who are afflicted and isvery costly for families and society.[1] Although the etiology ofschizophrenia is still unknown and no cure has yet beenfound, it is treatable, and pharmacological therapy often producessatisfactory results. Among the various antipsychoticdrugs in use, clozapine is widely recognized as one ofthemost clinically effective agents, even if it elicits significant sideeffects such as metabolic disorders and agranulocytosis. Clozapineand the closely related compound olanzapine are goodexamples ofdrug s with a complex multi-receptor profile ;[2]they have affinities toward serotonin, dopamine, a adrenergic,muscarinic, and histamine receptors, among others.

Assessment of angiotensin II receptor blockade in humans using a standardized angiotensin II receptor-binding assay.

An in vitro angiotensin II (AngII) receptor-binding assay was developed to monitor the degree of receptor blockade in standardized conditions. This in vitro method was validated by comparing its results with those obtained in vivo with the injection of exogenous AngII and the measurement of the AngII-induced changes in systolic blood pressure. For this purpose, 12 normotensive subjects were enrolled in a double-blind, four-way cross-over study comparing the AngII receptor blockade induced by a single oral dose of losartan (50 mg), valsartan (80 mg), irbesartan (150 mg), and placebo. A significant linear relationship between the two methods was found (r = 0.723, n = 191, P<.001). However, there exists a wide scatter of the in vivo data in the absence of active AngII receptor blockade. Thus, the relationship between the two methods is markedly improved (r = 0.87, n = 47, P<.001) when only measurements done 4 h after administration of the drugs are considered (maximal antagonist activity observed in vivo) suggesting that the two methods are equally effective in assessing the degree of AT-1 receptor blockade, but with a greatly reduced variability in the in vitro assay. In addition, the pharmacokinetic/pharmacodynamic analysis performed with the three antagonists suggest that the AT-1 receptor-binding assay works as a bioassay that integrates the antagonistic property of all active drug components of the plasma. This standardized in vitro-binding assay represents a simple, reproducible, and precise tool to characterize the pharmacodynamic profile of AngII receptor antagonists in humans.

A short motif in Drosophila SECIS Binding Protein 2 provides differential binding affinity to SECIS RNA hairpins

Selenoproteins contain the amino acid selenocysteine which is encoded by a UGA Sec codon. Recoding UGA Sec requires a complex mechanism, comprising the cis-acting SECIS RNA hairpin in the 3′UTR of selenoprotein mRNAs, and trans-acting factors. Among these, the SECIS Binding Protein 2 (SBP2) is central to the mechanism. SBP2 has been so far functionally characterized only in rats and humans. In this work, we report the characterization of the Drosophila melanogaster SBP2 (dSBP2). Despite its shorter length, it retained the same selenoprotein synthesis-promoting capabilities as the mammalian counterpart. However, a major difference resides in the SECIS recognition pattern: while human SBP2 (hSBP2) binds the distinct form 1 and 2 SECIS RNAs with similar affinities, dSBP2 exhibits high affinity toward form 2 only. In addition, we report the identification of a K (lysine)-rich domain in all SBP2s, essential for SECIS and 60S ribosomal subunit binding, differing from the well-characterized L7Ae RNA-binding domain. Swapping only five amino acids between dSBP2 and hSBP2 in the K-rich domain conferred reversed SECIS-binding properties to the proteins, thus unveiling an important sequence for form 1 binding.

The loss of GLUT2 expression in the pancreatic beta-cells of diabetic db/db mice is associated with an impaired DNA-binding activity of islet-specific trans-acting factors.

GLUT2 expression is reduced in the pancreatic beta-cells of several diabetic animals. The transcriptional control of the gene in beta-cells involves at least two islet-specific DNA-binding proteins, GTIIa and PDX-1, which also transactivates the insulin, somatostatin and glucokinase genes. In this report, we assessed the DNA-binding activities of GTIIa and PDX-1 to their respective cis-elements of the GLUT2 promoter using nuclear extracts prepared from pancreatic islets of 12 week old db/db diabetic mice. We show that the decreased GLUT2 mRNA expression correlates with a decrease of the GTIIa DNA-binding activity, whereas the PDX-1 binding activity is increased. In these diabetic animals, insulin mRNA expression remains normal. The adjunction of dexamethasone to isolated pancreatic islets, a treatment previously shown to decrease PDX-1 expression in the insulin-secreting HIT-T15 cells, has no effect on the GTIIa and PDX-1 DNA-binding activities. These data suggest that the decreased activity of GTIIa, in contrast to PDX-1, may be a major initial step in the development of the beta-cell dysfunction in this model of diabetes.

Synthesis, binding affinity, and molecular docking analysis of new benzofuranone derivative as pontential antipsychotics

The complex etiology of schizophrenia has prompted researchers to develop clozapine-related multitargetstrategies to combat its symptoms. Here we describe a series of new 6-aminomethylbenzofuranones in aneffort to find new chemical structures with balanced affinities for 5-HT2 and dopamine receptors. Throughbiological and computational studies of 5-HT2A and D2 receptors, we identified the receptor serine residuesS3.36 and S5.46 as the molecular keys to explaining the differences in affinity and selectivity betweenthese new compounds for this group of receptors. Specifically, the ability of these compounds to establishone or two H-bonds with these key residues appears to explain their difference in affinity. In addition, wedescribe compound 2 (QF1004B) as a tool to elucidate the role of 5-HT2C receptors in mediating antipsychoticeffects and metabolic adverse events. The compound 16a (QF1018B) showed moderate to high affinitiesfor D2 and 5-HT2A receptors, and a 5-HT2A/D2 ratio was predictive of an atypical antipsychotic profile.

Deletion of the RNA-binding proteins ZFP36L1 and ZFP36L2 leads to perturbed thymic development and T lymphoblastic leukemia.

ZFP36L1 and ZFP36L2 are RNA-binding proteins (RBPs) that interact with AU-rich elements in the 3' untranslated region of mRNA, which leads to mRNA degradation and translational repression. Here we show that mice that lacked ZFP36L1 and ZFP36L2 during thymopoiesis developed a T cell acute lymphoblastic leukemia (T-ALL) dependent on the oncogenic transcription factor Notch1. Before the onset of T-ALL, thymic development was perturbed, with accumulation of cells that had passed through the beta-selection checkpoint without first expressing the T cell antigen receptor beta-chain (TCRbeta). Notch1 expression was higher in untransformed thymocytes in the absence of ZFP36L1 and ZFP36L2. Both RBPs interacted with evolutionarily conserved AU-rich elements in the 3' untranslated region of Notch1 and suppressed its expression. Our data establish a role for ZFP36L1 and ZFP36L2 during thymocyte development and in the prevention of malignant transformation.

Tumor necrosis factor and transforming growth factor β regulate clock genes by controlling the expression of the cold inducible RNA-binding protein (CIRBP).

The circadian clock drives the rhythmic expression of a broad array of genes that orchestrate metabolism, sleep wake behavior, and the immune response. Clock genes are transcriptional regulators engaged in the generation of circadian rhythms. The cold inducible RNA-binding protein (CIRBP) guarantees high amplitude expression of clock. The cytokines TNF and TGFβ impair the expression of clock genes, namely the period genes and the proline- and acidic amino acid-rich basic leucine zipper (PAR-bZip) clock-controlled genes. Here, we show that TNF and TGFβ impair the expression of Cirbp in fibroblasts and neuronal cells. IL-1β, IL-6, IFNα, and IFNγ do not exert such effects. Depletion of Cirbp is found to increase the susceptibility of cells to the TNF-mediated inhibition of high amplitude expression of clock genes and modulates the TNF-induced cytokine response. Our findings reveal a new mechanism of cytokine-regulated expression of clock genes.