The Brown Dwarf Kinematics Project (BDKP): V. Radial and rotational velocities of T Dwarfs from Keck/NIRSPEC high-resolution spectroscopy

Stars and planetary system

A genomic approach to elucidating grass flower development

In sugarcane (Saccharum sp) as with other species of grass, at a certain moment of its life cycle the vegetative meristem is converted into an inflorescence meristem which has at least two distinct inflorescence branching steps before the spikelet meristem terminates in the production of a flower (floret). In model dicotyledonous species such successive conversions of meristem identities and the concentric arrangement of floral organs in specific whorls have both been shown to be genetically controlled. Using data from the Sugarcane Expressed Sequence Tag (EST) Project (SUCEST) database, we have identified all sugarcane proteins and genes putatively involved in reproductive meristem and flower development. Sequence comparisons of known flower-related genes have uncovered conserved evolutionary pathways of flower development and flower pattern formation between dicotyledons and monocotyledons, such as some grass species. We have paid special attention to the analysis of the MADS-box multigene family of transcription factors that together with the APETALA2 (AP2) family are the key elements of the transcriptional networks controlling plant reproductive development. Considerations on the evolutionary developmental genetics of grass flowers and their relation to the ABC homeotic gene activity model of flower development are also presented.<br>Como na maior parte das gramíneas, num determinado momento do seu ciclo de vida, o meristema vegetativo da cana-de-açúcar é convertido em meristema reprodutivo. Em cana-de-açúcar há pelo menos duas conversões meristemáticas distintas entre a indução para o florescimento e a formação do florete. Em espécies dicotiledôneas modelo, a conversão sucessiva das identidades dos meristemas, bem como o arranjo concêntrico de órgãos florais são controlados geneticamente. Todos os genes e/ou proteínas sabidamente envolvidos no desenvolvimento floral foram anotados e identificados no banco de dados do SUCEST (Sugarcane EST Project). Comparações de seqüências entre genes reconhecidamente envolvidos no controle do desenvolvimento floral revelaram a conservação evolutiva entre os mecanismos de formação do padrão de desenvolvimento floral entre mono- e dicotiledôneas, bem como entre as gramíneas. Nossos estudos se concentraram na análise das famílias multigênicas dos fatores de transcrição do tipo MADS-box e AP2, uma vez que estes têm um papel importante na regulação do desenvolvimento reprodutivo vegetal. Também são apresentadas considerações sobre a genética evolutiva do desenvolvimento das flores de gramíneas e sua relação com o modelo ABC do desenvolvimento floral

Evo-devo and the search for homology (“sameness”) in biological systems

Developmental biology and evolutionary studies have merged into evolutionary developmental biology ("evo-devo”). This synthesis already influenced and still continues to change the conceptual framework of structural biology. One of the cornerstones of structural biology is the concept of homology. But the search for homology ("sameness”) of biological structures depends on our favourite perspectives (axioms, paradigms). Five levels of homology ("sameness”) can be identified in the literature, although they overlap to some degree: (i) serial homology (homonomy) within modular organisms, (ii) historical homology (synapomorphy), which is taken as the only acceptable homology by many biologists, (iii) underlying homology (i.e., parallelism) in closely related taxa, (iv) deep evolutionary homology due to the "same” master genes in distantly related phyla, and (v) molecular homology exclusively at gene level. The following essay gives emphasis on the heuristic advantages of seemingly opposing perspectives in structural biology, with examples mainly from comparative plant morphology. The organization of the plant body in the majority of angiosperms led to the recognition of the classical root-shoot model. In some lineages bauplan rules were transcended during evolution and development. This resulted in morphological misfits such as the Podostemaceae, peculiar eudicots adapted to submerged river rocks. Their transformed "roots” and "shoots” fit only to a limited degree into the classical model which is based on either-or thinking. It has to be widened into a continuum model by taking over elements of fuzzy logic and fractal geometry to accommodate for lineages such as the Podostemacea

"Jairus, His Daughter, and the Haemorrhaging Woman (Mk. 5:21-43; Mt. 9:18-26; Lk. 8:40-56): Research Survey of a Gospel Story about People in Distress."

This article examines the history of interpretation of the pericope of the healing of the haemorrhaging woman and the raising of Jairus’ daughter (Mk 5.21-43; Mt. 9.18-26; Lk. 8.40-56). It starts with the earliest attempts to harmonize the synoptic accounts, and reviews medieval allegorical interpretations, historical-critical theories, including the apparent death (coma) theory, D.F. Strauss and mythical interpretation, form-criticism, the question of sources, literary and narrative approaches, socio-critical (feminist) interpretation, psychoanalytical criticism, and contextual (poststructural) readings

Flower Development

Flowers are the most complex structures of plants. Studies of Arabidopsis thaliana, which has typical eudicot flowers, have been fundamental in advancing the structural and molecular understanding of flower development. The main processes and stages of Arabidopsis flower development are summarized to provide a framework in which to interpret the detailed molecular genetic studies of genes assigned functions during flower development and is extended to recent genomics studies uncovering the key regulatory modules involved. Computational models have been used to study the concerted action and dynamics of the gene regulatory module that underlies patterning of the Arabidopsis inflorescence meristem and specification of the primordial cell types during early stages of flower development. This includes the gene combinations that specify sepal, petal, stamen and carpel identity, and genes that interact with them. As a dynamic gene regulatory network this module has been shown to converge to stable multigenic profiles that depend upon the overall network topology and are thus robust, which can explain the canalization of flower organ determination and the overall conservation of the basic flower plan among eudicots. Comparative and evolutionary approaches derived from Arabidopsis studies pave the way to studying the molecular basis of diverse floral morphologies