Inflorescence and floral development of Dahlstedtia species (Leguminosae: Papilionoideae: Millettieae)

Inflorescence and floral development of two tropical legume trees, Dahlstedtia pinnata and Dahlstedlia pentaphylla, occurring in the Atlantic Forest of south-eastern and southern Brazil, were investigated and compared with other papilionoids. Few studies have been made of floral development in tribe Millettieae, and this paper is intended to fill that gap in our knowledge. Dahlstedtia species have an unusual inflorescence type among legumes, the pseudoraceme, which comprises axillary units of three or more flowers, each with a subtending bract. Each flower exhibits a pair of opposite bractcoles. The order of flower initiation is acropetal; inception of the floral organs is as follows: sepals (5), petals (5), carpel (1) plus outer stamens (5) and finally inner stamens (5). Organ initiation in sepal, petal and inner stamen whorls is unidirectional; the carpel cleft is adaxial. The vexillum originates from a tubular-shaped primordium in mid-development and is larger than other petals at maturity, covering the keels. The filament tube develops later after initiation of inner-stamen primordia. Floral development in Dahlstedtia is almost always similar to other papilionoids, especially species of Phaseoleae and Sophoreae. But one important difference is the precocious ovule initiation (open carpel with ovules) in Dahlstedtia, the third citation of this phenomenon for papilionoids. No suppression, organ loss or anomalies occur in the order of primordia initiation or structure. Infra-generic differences in the first stages of ontogeny are rare; however, different species of Dahlstedtia are distinguished by the differing distribution pattern of secretory cavities in the flower. (C) 2009 Elsevier GmbH. All rights reserved.

Genes that code for T cell signaling proteins establish transcriptional regulatory networks during thymus ontogeny

Gene expression profiling by cDNA microarrays during murine thymus ontogeny has contributed to dissecting the large-scale molecular genetics of T cell maturation. Gene profiling, although useful for characterizing the thymus developmental phases and identifying the differentially expressed genes, does not permit the determination of possible interactions between genes. In order to reconstruct genetic interactions, on RNA level, within thymocyte differentiation, a pair of microarrays containing a total of 1,576 cDNA sequences derived from the IMAGE MTB library was applied on samples of developing thymuses (14-17 days of gestation). The data were analyzed using the GeneNetwork program. Genes that were previously identified as differentially expressed during thymus ontogeny showed their relationships with several other genes. The present method provided the detection of gene nodes coding for proteins implicated in the calcium signaling pathway, such as Prrg2 and Stxbp3, and in protein transport toward the cell membrane, such as Gosr2. The results demonstrate the feasibility of reconstructing networks based on cDNA microarray gene expression determinations, contributing to a clearer understanding of the complex interactions between genes involved in thymus/thymocyte development.

Life-history, thallus ontogeny, and the effects of temperature, irradiance and salinity on growth of the edible green seaweed Gayralia spp. (Chlorophyta) from Southern Brazil

Gayralia K.L. Vinogr. is a monostromatic green alga of commercial importance in the southern Brazil, and its cultivation is being considered. This paper reports some basic aspects of the biology of this poorly known genus. Two populations of Gayralia spp., from outer and inner sectors of Paranagua Bay, showed an asexual life history with a distinct pattern of thallus ontogeny. In one population (Gayralia sp. 1), zooids developed an expanded monostromatic blade directly, while in the other (Gayralia sp. 2) zooids produced an intermediate saccate stage, before giving rise to a monostromatic blade. Thalli of the two species differ in size and in cell diameter. The effects of temperature (16-30 degrees C), irradiance (50-100 mu mol photons m(-2) s(-1)), and salinity (5-40 psu) on the growth of both populations were assessed. Plantlets of Gayralia sp. 1 from in vitro cultures showed a broader tolerance to all salinity and irradiance levels tested, with the highest growth rate (GR; mean 17% day-1) at 21.5 degrees C and 100 mu mol photons m(-2) s(-1). Plantlets of Gayralia sp. 1 collected during the winter in the field showed higher GR, ranging from 5% day(-1) to 7.5% day(-1) in salinities from 20 to 40 psu, and 2.0% day(-1) and 4.3% day(-1) for plantlets collected during the summer. Gayralia sp. 2 from the field showed highest GR at salinity of 15 psu. These results suggest distinct physiological responses of the two species, in accordance with their distribution: Gayralia sp. 2 is limited to the inner areas of the estuary, while Gayralia sp. 1 grows in outer areas, where salinity values are higher than 20 psu. These data indicate that Gayralia sp. 1 has a higher potential for aquaculture than Gayralia sp. 2 due to its larger thalli, higher GR, and wider tolerance to environmental variations.

Embryonic, Larval, and Juvenile Development of the Sea Biscuit Clypeaster subdepressus (Echinodermata: Clypeasteroida)

Sea biscuits and sand dollars diverged from other irregular echinoids approximately 55 million years ago and rapidly dispersed to oceans worldwide. A series of morphological changes were associated with the occupation of sand beds such as flattening of the body, shortening of primary spines, multiplication of podia, and retention of the lantern of Aristotle into adulthood. To investigate the developmental basis of such morphological changes we documented the ontogeny of Clypeaster subdepressus. We obtained gametes from adult specimens by KCl injection and raised the embryos at 26 degrees C. Ciliated blastulae hatched 7.5 h after sperm entry. During gastrulation the archenteron elongated continuously while ectodermal red-pigmented cells migrated synchronously to the apical plate. Pluteus larvae began to feed in 3 d and were similar to 20 d old at metamorphosis; starved larvae died 17 d after fertilization. Postlarval juveniles had neither mouth nor anus nor plates on the aboral side, except for the remnants of larval spicules, but their bilateral symmetry became evident after the resorption of larval tissues. Ossicles of the lantern were present and organized in 5 groups. Each group had 1 tooth, 2 demipyramids, and 2 epiphyses with a rotula in between. Early appendages consisted of 15 spines, 15 podia (2 types), and 5 sphaeridia. Podial types were distributed in accordance to Loven's rule and the first podium of each ambulacrum was not encircled by the skeleton. Seven days after metamorphosis juveniles began to feed by rasping sand grains with the lantern. Juveniles survived in laboratory cultures for similar to 9 months and died with <500 mu m wide, a single open sphaeridium per ambulacrum, aboral anus, and no differentiated food grooves or petaloids. Tracking the morphogenesis of early juveniles is a necessary step to elucidate the developmental mechanisms of echinoid growth and important groundwork to clarify homologies between irregular urchins.

Identification of Novel Immunoregulatory Molecules in Human Thymic Regulatory CD4(+)CD25(+) T Cells by Phage Display

Thymic CD4(+)CD25(+) cells play an important role in immune regulation and are continuously developed in the thymus as an independent lineage. How these cells are generated, what are their multiple pathways of suppressive activity and which are their specific markers are questions that remain unanswered. To identify molecules involved in the function and development of human CD4(+)CD25(+) T regulatory cells we targeted thymic CD4(+)CD25(+) cells by peptide phage display. A phage library containing random peptides was screened ex vivo for binding to human thymic CD4(+)CD25(+) T cells. After four rounds of selection on CD4(+)CD25(+) enriched populations of thymocytes, we sequenced several phage displayed peptides and selected one with identity to the Vitamin D Receptor (VDR). We confirmed the binding of the VDR phage to active Vitamin D in vitro, as well as the higher expression of VDR in CD4(+)CD25(+) cells. We suggest that differential expression of VDR on natural Tregs may be related to the relevance of Vitamin D in function and ontogeny of these cells.

Intercellular transport of epidermis-expressed MADS domain transcription factors and their effect on plant morphology and floral transition

P>During the lifetime of an angiosperm plant various important processes such as floral transition, specification of floral organ identity and floral determinacy, are controlled by members of the MADS domain transcription factor family. To investigate the possible non-cell-autonomous function of MADS domain proteins, we expressed GFP-tagged clones of AGAMOUS (AG), APETALA3 (AP3), PISTILLATA (PI) and SEPALLATA3 (SEP3) under the control of the MERISTEMLAYER1 promoter in Arabidopsis thaliana plants. Morphological analyses revealed that epidermal overexpression was sufficient for homeotic changes in floral organs, but that it did not result in early flowering or terminal flower phenotypes that are associated with constitutive overexpression of these proteins. Localisations of the tagged proteins in these plants were analysed with confocal laser scanning microscopy in leaf tissue, inflorescence meristems and floral meristems. We demonstrated that only AG is able to move via secondary plasmodesmata from the epidermal cell layer to the subepidermal cell layer in the floral meristem and to a lesser extent in the inflorescence meristem. To study the homeotic effects in more detail, the capacity of trafficking AG to complement the ag mutant phenotype was compared with the capacity of the non-inwards-moving AP3 protein to complement the ap3 mutant phenotype. While epidermal expression of AG gave full complementation, AP3 appeared not to be able to drive all homeotic functions from the epidermis, perhaps reflecting the difference in mobility of these proteins.

Characterization of unisexual flower development in the endangered mahogany tree Swietenia macrophylla King. (Meliaceae)

The selection of candidate plus trees of desirable phenotypes from tropical forest trees and the rapid devastation of the natural environments in which these trees are found have created the need for a more detailed knowledge of the floral and reproductive biology of tropical tree species. In this article, the organogenic processes related to unisexual flower development in tropical mahogany, Swietenia macrophylla, are described. Mahogany inflorescences at different developmental stages were evaluated using scanning electron microscopy or optical microscopy of histological sections. The unisexual flowers of S. macrophylla are usually formed in a thyrse, in which the positions of the female and male flowers are not random. Differences between male and female flowers arise late during development. Both female and male flowers can only be structurally distinguished after stage 9, where ovule primordia development is arrested in male flowers and microspore development is aborted in female flower anthers. After this stage, male and female flowers can be distinguished by the naked eye as a result of differences in the dimensions of the gynoecium. The floral characteristics of S. macrophylla (distribution of male and female flowers within the inflorescence, and the relative number of male to female flowers) have practical implications for conservation strategies of this endangered species. (c) 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 156, 529-535.

Occurrence of secretory structures in underground systems of seven Asteraceae species

In contrast with the abundance of anatomical studies of secretory structures on aerial vegetative organs of Asteraceae species, the information about secretory structures on thickened subterranean organs is sparse. The aim of this study was to investigate the occurrence of secretory structures on thickened and nonthickened subterranean organs of seven Asteraceae species from three tribes: Eupatorieae (Chromolaena squalida and Gyptis lanigera), Vernonieae (Chresta sphaerocephala, Lessingianthus bardanoides, L. glabratus and Orthopappus angustifolius), and Plucheeae (Pterocaulon angustifolium). The specimens were collected in areas of cerrado, from the State of Sao Paulo, Brazil. All species of the tribe Vernonieae studied exhibited endodermic cells, other than the epithelial cells of the canal, with secretory activity in the roots. In C. sphaerocephala roots, two types of endodermic cell were found, but only one had secretory activity. Secretory canals were found in the tuberous and nontuberous roots of all studied species. These data agree with the results from the literature for Asteraceae species. Here, we describe for the first time in Asteraceae the presence of secretory idioblasts in C. sphaerocephala. Secretory trichomes are present in the Orthopappus angustifolius rhizophore. Histochemical tests have shown that all types of secretory structure possess substances containing lipids. (C) 2008 The Linnean Society of London.

Anatomical development of the pericarp and seed of Oncidium flexuosum Sims (ORCHIDACEAE)

Interpretation of the anatomical structure of the ovary and fruit of the Orchidaceae family is still controversial, which makes it difficult to understand the development and dehiscence of the fruit. The genus Oncidium is polyphyletic and is currently the subject of taxonomic studies. In this study, we have investigated the anatomical development of the pericarp and seed of Oncidium flexuosum Sims to determine important diagnostic characters that, along with molecular data, can assist in defining this group. We have found a new anatomical characteristic of the family: the presence of precursor cells for fruit dehiscence, which were visible from the beginning of development and located on the outer walls of the sterile valves. In contrast with what has been observed by different authors with other species, in the mature fruit of O. flexuosum, only the endocarp of the fertile valves and a few cells near the exocarp and the vascular bundle in the sterile valves show parietal thickening, while the rest remains parenchymatous. During the development of the ovule and embryo, we have shown that the embryonic sac of this species has eight nuclei and that the embryo has a long and elaborate suspensor. (C) 2011 Elsevier GmbH. All rights reserved.

Floral anatomy of the Lecointea clade (Leguminosae, Papilionoideae, Swartzieae sensu lato)

Flower and inflorescence anatomy and morphology of Exostyles, Harleyodendron, Holocalyx, Lecointea, and Zollernia (Leguminosae, Lecointea clade) were studied. Features common to all genera but otherwise rare within the Leguminosae include: (1) the presence of phenolic compounds in the epidermal cells of the anthers and subepidermal cells of the bracteoles, sepals, petals, and ovaries (absent in Holocalyx balansae); (2) simple trichomes on the adaxial base of the bracteoles and on the surface of the calyx and ovaries; and (3) tapetum persisting until the androspores are formed. Other notable anatomical features are: (1) colleters on the adaxial bases of the bracts and bracteoles of Holocalyx balansae and Zollernia ilicifolia; (2) trichomes on the anthers of Harleyodendron unifoliolatum, Holocalyx balansae, Lecointea hatschbachii, Zollernia ilicifolia and Z. magnifica; (3) osmophores on the petals of Exostyles godoyensis; (4) asynchronous pollen development in the anthers of Holocalyx balansae and Zollernia magnifica; and (5) vascular bundles surrounded by lignified fibers in Harleyodendron unifoliolatum. These anatomical characters are discussed according to their possible phylogenetic implications.

The oleoresin secretory system in seedlings and adult plants of copaiba (Copaifera langsdorffii Desf., Leguminosae-Caesalpinioideae)

The ecological and economic importance of oleoresin produced by Copaifera langsdorffii is well established. This study aims to investigate the ontogeny, anatomy and ultrastructure of the internal glands of C. langsdorffii during plant development. Samples were processed for light and electron microscopy and a specific technique was applied to impregnate endomembranes. Internal secretory glands were observed in the hypocotyl, epicotyl and eophylls of seedlings, and in the primary stem, pulvinus, petiole, rachis and leaf blade of adult plants. Canals and cavities show differential distribution. They arise from ground meristem cells, and the lumen is first formed by schizogenesis followed by later schizolysigenous development. The dense cytoplasm of epithelial cells shows mitochondria, plastids without thylakoids, polyribosomes and endoplasmic reticulum. A periplastidial reticulum was also observed. Secretion is released by eccrine, granulocrine and holocrine processes. Lipophilic and hydrophilic compounds were histochemically detected in both canals and cavities, whereas resin was detected only in canals. The presence of these substances has been associated with plants` defences against dehydration, as well as against attacks from herbivores and pathogens, from seedling stage onwards. (C) 2011 Elsevier GmbH. All rights reserved.

ELUCIDATING ENIGMATIC FLORAL ISSUES IN COPAIFERA LANGSDORFFII DESF. (LEGUMINOSAE, CAESALPINIOIDEAE)

This study focuses on the floral development of Copaifera langsdorffii to elucidate uncertain features in its floral morphology, such as the tetramerous calyx, lack of petals, blackened anthers and their supposed sterility, as well as polyembryony. Buds and flowers were dissected and prepared for examination under scanning electron and light microscopes. The floral apex initiates two bracteoles, five sepals, five petals, five outer stamens, five inner stamens, and one carpel. Order is helical for sepals, reversed unidirectional for the petals, and unidirectional for two whorls of stamens. The tetramerous calyx results from the union of two adaxial sepal primordia, which forms one large sepal and three other smaller sepals. Although the flower lacks petals, the petal primordia are initiated but do not elongate like the other floral organs, remaining as petal rudiments. Ten stamens are formed in two distinct whorls. Formation within each whorl is almost simultaneous, and the inner whorl is formed shortly after the outer. During organ elongation, the inner stamen primordia bases are reoriented outward, resulting in a single whorl of stamens. The darkened anthers have viable pollen grains. Thus, there is no relation between sterility and the dark coloration of the anthers. No signs of extranumerary embryos are observed; therefore, polyembryony is not confirmed. Although studies on floral development of Detarieae have been reported, few Neotropical genera of the tribe (such as Copaifera) have been studied.

Biological features of a puzzling symbiotic association between the hermit crab Dardanus insignis and the porcellanid crab Porcellana Sayana (Crustacea)

The symbiotic lifestyle is widespread among porcellanid crabs, which maintain ecological and co-evolutionary associations with annelid polychaetes, poriferans, cnidarians, echinoderms, gastropod. mollusks, and other crustaceans such as shrimps and hermit crabs, among others. We investigated the ecological association between the hermit crab Dardanus insignis and the porcellanid Porcellana sayana, in southeastern Brazil. Porcellanid crabs, hermit crabs, and available shells were collected monthly from July 2001 to June 2003, with a shrimp boat equipped with two double-rig trawl nets. The majority of P. sayana specimens were collected in shells occupied by D. insignis (96.6%); a few were found in empty shells (3.4%). The catch of both symbionts and hosts increased with increasing depth, with the highest occurrence at 35 m. The F. sayana crabs of various sizes could be found solitary or forming aggregations of up to 14 individuals per host, showing no sex or size segregation. In spite of the high diversity of shell species occupied by the hermit crabs and also available in the field, only a few of them were also utilized by P. sayana. The majority (93%) of shells utilized by P. sayana also hosted other symbiont species, constituting the basis of extensive symbiotic complexes. Thus, the ecological relationship between D. insignis and P. sayana may be classified as a non-obligate and non-specific symbiosis that may also involve other facultative organisms such as sea anemones. (C) 2008 Elsevier B.V. All rights reserved.

Floral developmental morphology of three Indigofera species (Leguminosae) and its systematic significance within Papilionoideae

Inflorescence and floral development of three species of Indigofera (Leguminosae-Papilionoideae), I. lespedezioides, I. spicata, and I. suffruticosa, were investigated and compared with that of other papilionoid groups, especially with members of the recently circumscribed Millettioid clade, which was merged as sister to Indigofereae in a recent cladistic analysis. Although Indigofera is a genus of special interest, because of its great richness in species and its economic importance, few studies have been made of floral development in the genus or in Indigofereae as a whole. Flower buds and inflorescences were analysed at several stages of development in the three species. Our results confirmed that Indigofera species bear a usual inflorescence type among legumes, the raceme, which comprises flowers initiated in acropetal succession, each with a subtending bract and no bracteoles initiated. The inception of the floral organs is as follows: sepals (5), petals (5), carpel (1), outer stamens (5), and, finally, inner stamens (5). Organ initiation in the sepal, petal, and both stamen whorls is unidirectional, from the abaxial side; the carpel cleft is adaxial. The vexillum is larger than other petals at maturity, covering the keels, which are fused edge-to-edge. Nine filaments are fused to form an adaxially open sheath, and the adaxial stamen of the inner whorl remains free (diadelphous androecium) in the mid-stage of development. Most of the infra-generic differences occurred in the later stages of development. Data on floral development in Indigofera obtained here were also compared with those from other members of Papilionoideae. This comparison showed that the early expression of zygomorphy is shared with other members of the Millettioid clade but is rarely found in other papilionoids, corresponding to a hypothetically morphological synapomorphy in the pair Indigoferae plus millettioids.

Insights into the organization of dorsal spinal cord pathways from an evolutionarily conserved raldh2 intronic enhancer

Comparative studies of the tetrapod raldh2 (aldh1a2) gene, which encodes a retinoic acid (RA) synthesis enzyme, have led to the identification of a dorsal spinal cord enhancer. Enhancer activity is directed dorsally to the roof plate and dorsal-most (dl1) interneurons through predicted Tcf- and Cdx-homeodomain binding sites and is repressed ventrally via predicted Tgif homeobox and ventral Lim-homeodomain binding sites. Raldh2 and Math1/Cath1 expression in mouse and chicken highlights a novel, transient, endogenous Raldh2 expression domain in dl1 interneurons, which give rise to ascending circuits and intraspinal commissural interneurons, suggesting roles for RA in the ontogeny of spinocerebellar and intraspinal proprioceptive circuits. Consistent with expression of raldh2 in the dorsal interneurons of tetrapods, we also found that raldh2 is expressed in dorsal interneurons throughout the agnathan spinal cord, suggesting ancestral roles for RA signaling in the ontogenesis of intraspinal proprioception.