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Developmental Series (developmental + series)
Selected AbstractsChondrocranial development in larval Rana sylvatica (Anura: Ranidae): Morphometric analysis of cranial allometry and ontogenetic shape changeJOURNAL OF MORPHOLOGY, Issue 2 2002Peter M. Larson Abstract This study provides baseline quantitative data on the morphological development of the chondrocranium in a larval anuran. Both linear and geometric morphometric methods are used to quantitatively analyze size-related shape change in a complete developmental series of larvae of the wood frog, Rana sylvatica. The null hypothesis of isometry was rejected in all geometric morphometric and most linear morphometric analyses. Reduced major axis regressions of 11 linear chondrocranial measurements on size indicate a mixture of allometric and isometric scaling. Measurements in the otic and oral regions tend to scale with negative allometry and those associated with the palatoquadrate and muscular process scale with isometry or positive allometry. Geometric morphometric analyses, based on a set of 11 chondrocranial landmarks, include linear regression of relative warp scores and multivariate regression of partial warp scores and uniform components on log centroid size. Body size explains about one-quarter to one-third of the total shape variation found in the sample. Areas of regional shape transformation (e.g., palatoquadrate, otic region, trabecular horns) are identified by thin-plate spline deformation grids and are concordant with linear morphometric results. Thus, the anuran chondrocranium is not a static structure during premetamorphic stages and allometric patterns generally follow scaling predictions for tetrapod cranial development. Potential implications regarding larval functional morphology, cranial development, and chondrocranial evolution in anurans are discussed. J. Morphol. 252:131,144, 2002. © 2002 Wiley-Liss, Inc. [source] Hydathodal leaf teeth of Chloranthus japonicus (Chloranthaceae) prevent guttation-induced flooding of the mesophyllPLANT CELL & ENVIRONMENT, Issue 9 2005TAYLOR S. FEILD ABSTRACT Why the leaves of cold temperate deciduous and moisture-loving angiosperms are so often toothed has long puzzled biologists because the functional consequences of teeth remain poorly understood. Here we provide functional and structural evidence that marginal leaf teeth of Chloranthus japonicus, an understory herb, enable the release of guttation sap during root pressure. When guttation from teeth hydathodes was experimentally blocked, we found that the leaf intercellular airspaces became flooded. Measurements of chlorophyll a fluorescence revealed that internal flooding resulted in an inhibition of photosynthesis, most likely through the formation of a film of water within the leaf that reduced CO2 diffusion. Comparing a developmental series of leaves with and without teeth experimentally covered with wax, we found that teeth did not affect overall leaf stomatal conductance and CO2 uptake. However, maximal and effective light-saturation PSII quantum yields of teeth were found to be lower or equal to the surrounding lamina throughout leaf ontogeny. Collectively, our results suggest hydathodes and their development on teeth apices enable the avoidance of mesophyll flooding by root pressure. We discuss how these new findings bear on the potential physiological interpretations of models that apply leaf marginal traits to infer ancient climates. [source] Effects of Temperature Regime Through Premetamorphic Ontogeny on Shape of the Chondrocranium in the American Toad, Anaxyrus americanusTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 7 2008Michael E. Jorgensen Abstract If one considers the substantial amount of information that exists about phenotypic plasticity in amphibians, it is surprising that few studies have examined abiotic factors that influence phenotype through ontogeny. Phenotypic change and stability of morphology are artifacts of organisms that bear significant relevance to evolution within and among taxonomic groups. Here, we examine development as a phenotypically plastic aspect of larval anurans. Fertilized eggs of the American Toad, Anaxyrus (= Bufo) americanus (Holbrook, 1836), were obtained from two pairs of adults, and larvae were reared in four temperature treatments (constant Mean, constant High, constant Low, and Fluctuating regime [Low night,High day]); developmental series were collected from each treatment, representing larvae of this species from Gosner Stages 28,40. Cleared and stained larvae were analyzed with landmark-based geometric morphometric methods to facilitate examination of differences in overall shape change of the larval chondrocranium through ontogeny, as a result of developmental temperature or temperature regime. Changes in shape of the chondrocranium and in amount and direction of phenotypic change through ontogeny were found in response to temperature treatment and temperature regime. Mean chondrocranial shape of the Fluctuating regime was more similar to the consensus shape of the overall data set than were those of all other treatments. Given that differences in amount and direction of shape change were observed among these treatments and throughout ontogeny, one should consider the affects of abiotic factors (such as temperature) when rearing larval anurans for studies of developmental morphology. Anat Rec, 291:818-826, 2008. © 2008 Wiley-Liss, Inc. [source] Regulation of bone morphogenetic protein signalling in human pulmonary vascular development,THE JOURNAL OF PATHOLOGY, Issue 1 2008M Southwood Abstract The bone morphogenetic protein (BMP) type II receptor (BMPR-II) is predominantly expressed on the vascular endothelium in the adult lung. Although mutations in BMPR-II are known to underlie many cases of familial pulmonary arterial hypertension (FPAH), little is known regarding the expression of BMPs and their signalling pathways during normal lung development or the impact of BMPR-II mutations on endothelial cell function. We determined the cellular localization and expression levels of BMP4, BMP receptors, and activation of downstream signalling via phospho-Smad1 in a developmental series of human embryonic and fetal lungs by immunohistochemistry. The expression of BMP4 and BMP receptors was temporally and spatially regulated during lung development. BMPR-II expression correlated with phosphorylation of tissue Smad1 and was highest during the late pseudoglandular and early canalicular stage of lung development, when vasculogenesis is intense. Phospho-Smad1 expression was associated with markers of proliferation in endothelial cells. In vitro studies confirmed that BMPs 2 and 4 induced phosphorylation of Smad1/5 and pulmonary artery endothelial cell (PAEC) migration and proliferation. Adenoviral transfection of PAECs with mutant kinase-deficient BMPR-II, or siRNA knockdown of BMPR-II, inhibited Smad signalling and the proliferative response to BMP4. Our findings support a critical role for BMPs in lung vasculogenesis. Dysfunctional BMP signalling in PAECs during development may lead to abnormal pulmonary vascular development and contribute to the pathogenesis of FPAH. Copyright © 2007 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. [source] | ||||||||||