Genome-wide identification and expression profiling of auxin response factor (ARF) gene family in maize

<p>Abstract</p> <p>Background</p> <p>Auxin signaling is vital for plant growth and development, and plays important role in apical dominance, tropic response, lateral root formation, vascular differentiation, embryo patterning and shoot elongation. Auxin Response Factors (ARFs) are the transcription factors that regulate the expression of auxin responsive genes. The <it>ARF </it>genes are represented by a large multigene family in plants. The first draft of full maize genome assembly has recently been released, however, to our knowledge, the <it>ARF </it>gene family from maize (<it>ZmARF </it>genes) has not been characterized in detail.</p> <p>Results</p> <p>In this study, 31 maize (<it>Zea mays </it>L.) genes that encode ARF proteins were identified in maize genome. It was shown that maize <it>ARF </it>genes fall into related sister pairs and chromosomal mapping revealed that duplication of <it>ZmARFs </it>was associated with the chromosomal block duplications. As expected, duplication of some <it>ZmARFs </it>showed a conserved intron/exon structure, whereas some others were more divergent, suggesting the possibility of functional diversification for these genes. Out of these 31 <it>ZmARF </it>genes, 14 possess auxin-responsive element in their promoter region, among which 7 appear to show small or negligible response to exogenous auxin. The 18 <it>ZmARF </it>genes were predicted to be the potential targets of small RNAs. Transgenic analysis revealed that increased miR167 level could cause degradation of transcripts of six potential targets (<it>ZmARF3</it>, <it>9</it>, <it>16</it>, <it>18</it>, <it>22 </it>and <it>30</it>). The expressions of maize <it>ARF </it>genes are responsive to exogenous auxin treatment. Dynamic expression patterns of <it>ZmARF </it>genes were observed in different stages of embryo development.</p> <p>Conclusions</p> <p>Maize <it>ARF </it>gene family is expanded (31 genes) as compared to <it>Arabidopsis </it>(23 genes) and rice (25 genes). The expression of these genes in maize is regulated by auxin and small RNAs. Dynamic expression patterns of <it>ZmARF </it>genes in embryo at different stages were detected which suggest that maize <it>ARF </it>genes may be involved in seed development and germination.</p

Iodine-125 brachytherapy for brain tumours - a review

Iodine-125 brachytherapy has been applied to brain tumours since 1979. Even though the physical and biological characteristics make these implants particularly attractive for minimal invasive treatment, the place for stereotactic brachytherapy is still poorly defined

Tendências da aquisição lexical em crianças em desenvolvimento normal e crianças com Alterações Específicas no Desenvolvimento da Linguagem Trends on lexical acquisition in children within normal development and children with developmental language disorder

O objetivo do presente estudo foi descrever as semelhanças e diferenças encontradas ao longo da aquisição lexical por crianças em desenvolvimento normal e crianças com Alterações Específicas no Desenvolvimento da Linguagem (AEDL), por meio de um amplo levantamento bibliográfico em bases de dados (SciELO, Lilacs, PubMed, Web of Science, Dedalus), que abrangeu as últimas décadas de estudos na área. Os estudos selecionados, de natureza observacional ou experimental, mostraram grande variedade de achados relacionados ao desenvolvimento do vocabulário, abrangendo as tendências e variações e também outras habilidades envolvidas no processo de aquisição lexical. De maneira geral, os resultados sugerem que as alterações lexicais que constituem um dos marcos inicialmente observados em crianças com AEDL são justificadas por dificuldades observadas em habilidades e/ou características influenciadas ou diretamente relacionadas aos mecanismos envolvidos no processamento da informação, que comprometem a qualidade e a recuperação das representações fonológicas e semânticas correspondentes a um novo item lexical. Entretanto, vários estudos sugerem que situações ostensivas e de grande suporte contextual que enfoquem poucas novas palavras favorecem a aquisição lexical de crianças com AEDL.<br>The aim of the present study was to describe the similarities and differences found throughout lexical acquisition between normally developing children and children with developmental language disorder through an extensive literature review. The search was carried out in the databases SciELO, Lilacs, PubMed, Web of Science and Dedalus, and covered the last decades of studies in the area. The selected studies, of observational or experimental nature, showed great variability of findings related to vocabulary development, describing tendencies and variations, and also other abilities enrolled in the lexical acquisition process. Generally, the results suggest that the lexical difficulties that constitute one of the first alterations observed in children with developmental language disorder are justified by difficulties in abilities and/or characteristics influenced or directly related to mechanisms involved in information processing, which compromise the quality and the retrieval of phonological and semantic representations corresponding to a new lexical item. However, many studies suggest that ostensive situations and great contextual support emphasizing few novel words facilitate the lexical acquisition of children with developmental language disorder