Consecutive Developmental Stages Research Articles

Growth and cellular patterns in the petal epidermis of Antirrhinum majus: empirical studies.

Analysis of cellular patterns in plant organs provides information about the orientation of cell divisions and predominant growth directions. Such an approach was employed in the present study in order to characterize growth of the asymmetrical wild-type dorsal petal and the symmetrical dorsalized petal of the backpetals mutant in Antirrhinum majus. The aims were to determine how growth in an initially symmetrical petal primordium leads to the development of mature petals differing in their symmetry, and to determine how specific cellular patterns in the petal epidermis are formed. Cellular patterns in the epidermis in both petal types over consecutive developmental stages were visualized and characterized quantitatively in terms of cell wall orientation and predominant types of four-cell packets. The data obtained were interpreted in terms of principal directions of growth (PDGs). Both petal types grew predominantly along the proximo-distal axis. Anticlinal cell walls in the epidermis exhibited a characteristic fountain-like pattern that was only slightly modified in time. New cell walls were mostly perpendicular to PDG trajectories, but this alignment could change with wall age. The results indicate that the predominant orientation of cell division planes and the fountain-like cellular pattern observed in both petal types may be related to PDGs. The difference in symmetry between the two petal types arises because PDG trajectories in the field of growth rates (growth field) controlling petal growth undergo gradual redefinition. This redefinition probably takes place in both petal types but only in the wild-type does it eventually lead to asymmetry in the growth field. Two scenarios of how redefinition of PDGs may contribute to this asymmetry are considered.

Gene-Sharing Networks Reveal Organizing Principles of Transcriptomes in Arabidopsis and Other Multicellular Organisms

Understanding tissue-related gene expression patterns can provide important insights into gene, tissue, and organ function. Transcriptome analyses often have focused on housekeeping or tissue-specific genes or on gene coexpression. However, by analyzing thousands of single-gene expression distributions in multiple tissues of Arabidopsis thaliana, rice (Oryza sativa), human (Homo sapiens), and mouse (Mus musculus), we found that these organisms primarily operate by gene sharing, a phenomenon where, in each organism, most genes exhibit a high expression level in a few key tissues. We designed an analytical pipeline to characterize this phenomenon and then derived Arabidopsis and human gene-sharing networks, in which tissues are connected solely based on the extent of shared preferentially expressed genes. The results show that tissues or cell types from the same organ system tend to group together to form network modules. Tissues that are in consecutive developmental stages or have common physiological functions are connected in these networks, revealing the importance of shared preferentially expressed genes in conferring specialized functions of each tissue type. The networks provide predictive power for each tissue type regarding gene functions of both known and heretofore unknown genes, as shown by the identification of four new genes with functions in guard cell and abscisic acid response. We provide a Web interface that enables, based on the extent of gene sharing, both prediction of tissue-related functions for any Arabidopsis gene of interest and predictions concerning the relatedness of tissues. Common gene-sharing patterns observed in the four model organisms suggest that gene sharing evolved as a fundamental organizing principle of gene expression in diverse multicellular eukaryotes.

Occupational strategy of runner reed ( Phragmites japonica): Change of growth patterns with developmental aging

The characteristics of P. japonica stands growing along ten transect in an AFP were assessed. Especially those of the reproductive organs in terms of developmental stages were focused. Four consecutive stages were observed based on the existence of reproductive organs (flowers and stolons). Plants in the ‘stolon’ and ‘flower and stolon’ stages played a role as a colonizer by stolonization (the longest length of stolon was more than 9 m) while those in the ‘flower’ stage played a role as an occupant via forming tall and dense shoots on tussocks (more than 2 m and about 20 shoots per tussock including dead standing shoots). Consecutive developmental stages according to changes in growth patterns, particularly in the conversion of reproductive organ from asexual (stolon) to sexual (flower), was the critical strategy of P. japonica for efficient monotypic occupation. This occupational strategy of P. japonica also resulted in a sharp decrease of the plant species richness (two to three including P. japonica) growing in the same area with P. japonica in the mature (‘flower’) stage.

Attention demand and postural control in children with hearing deficit

To elucidate the mechanisms responsible for deteriorated postural control in children with hearing deficit (CwHD), we measured center-of-pressure (COP) variability, mean velocity and entropy in bipedal quiet stance (feet together) with or without the concurrent cognitive task (reaction to visual stimulus) on hard or foam surface in 29 CwHD and a control group of 29 typically developing children (CON). The CwHD displayed an overall decreased postural performance as compared to the CON in the medial–lateral plane ( p < 0.05). Standing on foam pad revealed slower simple reaction time in the CwHD ( p < 0.05) while the results on hard surface were not different. The CwHD decreased ( p < 0.05) the amount of attention invested in posture during dual task which accounted for the need of more cognitive resources to handle two tasks simultaneously than controls. It was unmistakable that the intergroup differences emerged when the tasks performed were relatively novel and untrained: feet together, foam pad, and reaction time. All these tasks, while being very easy for the CON, made the CwHD deteriorate postural or cognitive performance. These results unravel the difficulty in reaching the consecutive developmental stages in the CwHD and call for specific therapeutic modalities that might facilitate this development.

Fulvic acid affects proliferation and maturation phases in Abies cephalonica embryogenic cells

Embryogenic cell masses (ECM) of Abies cephalonica were grown on proliferation media in the presence and absence of fulvic acid (FA), whose molecular composition and conformational rigidity were evaluated by CPMAS- 13C NMR spectroscopy. To assess the physiological effects of this humic material during proliferation and maturation stages of somatic embryogenesis (SE), proliferation rate, proportion of consecutive developmental stages of pro-embryogenic masses (PEM), cellular ATP and glucose-6-phosphate were evaluated at regular intervals. FA increased the proliferation rate, especially during the early sampling days, and the percentage of PEM in their advanced developmental stage. Cellular ATP and glucose-6-phospahte were increased by FA pre-treatment during the maturation phase. Furthermore, the effects of the anti-auxin p-chlorophenoxyisobutyric acid (PCIB), such as a decrease of growth and the enhancement of PEM III induction, were inverted by FA. Proton pumping ATPase and PPase activities were decreased in microsomes from PCIB-treated ECM, while they increased in the presence of FA. This fulvic matter also induced a delay in somatic embryo formation during the maturation phase. Both the improvement of the PEM proliferation and the reduction of the subsequent maturation process of A. cephalonica are explained by a release from the complex humic structure of low molecular-weight molecules, which may interact with the plant hormonal signaling pathway. These effects appear to be related to the hydrophilic and conformationally labile nature of FA. The structure–activity relationship observed here suggests that the influence of FA on ECM may be attributed to specific bioactive molecules that are preferentially released from the FA loose superstructure.

Analysis of early embryonic great-vessel microcirculation in zebrafish using high-speed confocal μPIV

In the developing cardiovascular system, hemodynamic vascular loading is critical for angiogenesis and cardiovascular adaptation. Normal zebrafish embryos with transgenically-labeled endothelial and red blood cells provide an excellent in vivo model for studying the fluid-flow induced vascular loading. To characterize the developmental hemodynamics of early embryonic great-vessel microcirculation in the zebrafish embryo, two complementary studies (experimental and numerical) are presented. Quantitative comparison of the wall shear stress (WSS) at the first aortic arch (AA1) of wild-type zebrafish embryos during two consecutive developmental stages is presented, using time-resolved confocal micro-particle image velocimetry (μPIV). Analysis showed that there was significant WSS difference between 32 and 48 h post-fertilization (hpf) wild-type embryos, which correlates with normal arch morphogenesis. The vascular distensibility of the arch wall at systole and the acceleration/deceleration rates of time-lapse phase-averaged streamwise blood flow curves were also analyzed. To estimate the influence of a novel intermittent red-blood cell (RBC) loading on the endothelium, a numerical two-phase, volume of fluid (VOF) flow model was further developed with realistic in vivo conditions. These studies showed that near-wall effects and cell clustering increased WSS augmentation at a minimum of 15% when the distance of RBC from arch vessel wall was less than 3 μm or when RBC cell-to-cell distance was less than 3 μm. When compared to a smooth wall, the WSS augmentation increased by a factor of ~1.4 due to the roughness of the wall created by the endothelial cell profile. These results quantitatively highlight the contribution of individual RBC flow patterns on endothelial WSS in great-vessel microcirculation and will benefit the quantitative understanding of mechanotransduction in embryonic great vessel biology, including arteriovenous malformations (AVM).

Sugar and acid-related quality attributes and enzyme activities in strawberry fruits: Invertase is the main sucrose hydrolysing enzyme

This paper presents sugar and organic acid content and composition, the principal determinants of flavour, of strawberries of the cultivars Festival and Ventana at four consecutive developmental stages. The metabolite profiles of these two cultivars were very similar. Glucose was the predominant sugar at approximately twice the concentration of fructose and sucrose. Total acid concentrations were five times lower than total sugar concentrations in ripe berries, with citrate comprising roughly two thirds of the total acid content. The maximum extractable catalytic activities of key enzymes in the relevant metabolic pathways were also quantified during berry development, in an attempt to elucidate possible correlations. Sucrose synthase activity was very low or undetected, while neutral invertase activity was relatively high, suggesting that sucrose synthase does not make a significant contribution to sink strength in these cultivars. Three enzymes, invertase, pyrophosphate-dependent phosphofructokinase (PFP) and fructose-1,6-bisphosphatase (FBPase), showed distinct activity patterns during development and may affect sugar and acid accumulation and sugar composition of strawberries.

Differential expression of hippocampal connexins after acute hypoxia in the developing brain

Acute hypoxia at postnatal day (P) 10 is an accepted model of human neonatal hypoxia which results, among other consequences, in increased hippocampal excitability. Hypoxic–ischemic injury, which mimics stroke, has been shown to result in changes in connexins (Cxs), however, changes in Cxs have not been studied in the P10 hypoxia model. The aim of this study was to investigate changes in the hippocampal expression of three different connexins at consecutive developmental stages after acute hypoxia at P10 (10 min and 30 min after reoxygenation, P11, P14, P17, P29, and P45) as compared to sham manipulated pups. After acute hypoxia at P10, Cx30 protein levels were increased at 30 min after reoxygenation, at P11 and at P14, and then returned to control levels. Cx36 protein levels transiently decreased at P11 after acute hypoxia then returned to control levels. Cx43 protein levels did not change at any of the time points. Although changes in mRNA expression were observed during development for Cx30 only, acute hypoxia did not result in changes in mRNA expression of all these Cxs when compared to age matched controls suggesting that acute hypoxia induced posttranslational changes in protein expression.

Activated cAMP receptors switch encystation into sporulation.

Metazoan embryogenesis is controlled by a limited number of signaling modules that are used repetitively at successive developmental stages. The development of social amoebas shows similar reiterated use of cAMP-mediated signaling. In the model Dictyostelium discoideum, secreted cAMP acting on 4 cAMP receptors (cARs1-4) coordinates cell movement during aggregation and fruiting body formation, and induces the expression of aggregation and sporulation genes at consecutive developmental stages. To identify hierarchy in the multiple roles of cAMP, we investigated cAR heterogeneity and function across the social amoeba phylogeny. The gene duplications that yielded cARs 2-4 occurred late in evolution. Many species have only a cAR1 ortholog that duplicated independently in the Polysphondylids and Acytostelids. Disruption of both cAR genes of Polysphondylium pallidum (Ppal) did not affect aggregation, but caused complete collapse of fruiting body morphogenesis. The stunted structures contained disorganized stalk cells, which supported a mass of cysts instead of spores; cAMP triggered spore gene expression in Ppal, but not in the cAR null mutant, explaining its sporulation defect. Encystation is the survival strategy of solitary amoebas, and lower taxa, like Ppal, can still encyst as single cells. Recent findings showed that intracellular cAMP accumulation suffices to trigger encystation, whereas it is a complementary requirement for sporulation. Combined, the data suggest that cAMP signaling in social amoebas evolved from cAMP-mediated encystation in solitary amoebas; cAMP secretion in aggregates prompted the starving cells to form spores and not cysts, and additionally organized fruiting body morphogenesis. cAMP-mediated aggregation was the most recent innovation.

The distribution of motor proteins in the muscles and flame cells of the Schistosoma mansoni miracidium and primary sporocyst

Schistosoma mansoni eggs, miracidia and primary sporocysts were labelled with phalloidin-rhodamine to visualize filamentous actin structures. Analysis of these forms by confocal fluorescence microscopy revealed the presence of previously well-defined circular and longitudinal muscle layers. Besides these muscular layers that sustain and provide motility to these parasite forms, we found in these 3 consecutive developmental stages of the parasite previously unidentified actin-rich tubular structures. In the 3 forms, 4 actin-rich tubules could be observed by optical sectioning underneath the well-developed muscle layers. The tubules appear in pairs, transversal to the length of the parasite, and located towards the extremities. By using an anti-flame cell specific antibody we confirmed that the tubules co-localize with flame cells and also determined that the tubule core is filled with microtubules. The additional presence of myosin in these tubules strongly suggests that they are contractile structures.

Drinking and Na +/K + ATPase activity during early development of European sea bass, Dicentrarchus labrax: Ontogeny and short-term regulation following acute salinity changes

The short-term osmoregulatory capacity of sea bass ( Dicentrarchus labrax) larvae and juveniles at consecutive developmental stages was evaluated by an analysis of drinking rates and whole-body and branchial Na +/K + ATPase activity. The effect of acute salinity stress on those parameters was assessed from hatching to the juvenile stage. Drinking rate normalised to body weight (DR bw) decreased throughout postembryonic development. DR bw was not affected by salinity in yolk sac larvae. However, significant differences were observed in older larvae and in juveniles submitted to hypo- and hyperosmotic challenges. Post yolk sac larvae and juveniles always drink, but at a lower rate in hypoosmotic media compared to hyperosmotic media. A correlation was established between DR bw and blood osmolality during the postembryonic development of the sea bass. Na +/K + ATPase specific and total activity in whole larval homogenates decreased from hatching to the 5-mm yolk sac larva stage and increased in 10-mm stage larvae. The enzyme specific activity in the gills, from post yolk sac larvae to juveniles, decreased whereas the total activity increased during the same period. Developing sea bass have a better capacity to cope with hypoosmotic than hyperosmotic media.

In situ-RT-PCR and immunohistochemistry for the localisation of the mRNA of the alpha 3 chain of laminin and laminin-5 during human organogenesis.

Laminin-5 is known to be an integral part of the hemidesmosome and therefore responsible for the integrity of the connection of the epithelium to the basement membrane. This is also an important mechanism during embryonic development, as documented by studies in mice. In an attempt to elucidate its implication for human development we localised the mRNA of the alpha3 chain of laminin with the help of in situ RT-PCR, and the laminin-5 protein immunohistochemically. We systematically investigated kidney, lung, skin and intestinal tissue of consecutive developmental stages during human embryogenesis. From gw 6.5 onwards, the mRNA of the alpha3 chain of laminin was found exclusively in the cytoplasm of epithelial cells of the developing kidney, lung, skin and intestine. Interestingly, in the skin and intestine from gw 8 onwards, the superficial cell layers also stained positive for the mRNA, while the protein was still only found in the dermal-epidermal and enteric basement membrane zones. In all developing organs investigated, the mRNA of the alpha3 chain of laminin is strictly of epithelial origin and the corresponding protein localised in the underlying basement membrane zones. Due to this discrepancy, we postulate a broader role for laminin-5 during human embryogenesis, for example, for epithelial cell development, beyond its involvement in hemidesmosome formation and cell adhesion.

B cells are programmed to activate kappa and lambda for rearrangement at consecutive developmental stages.

Kappa and lambda, the two types of immunoglobulin light (L) chains present in mammals, contribute differently to the L chain pool of each species. Here we show that the extreme preponderance of kappa in the mouse results from programmed sequential activation of the kappa and lambda loci. Activation--a prerequisite of rearrangement--was monitored by analyzing transcription of unrearranged J-C clusters. Upon in vitro differentiation of a rearrangement-deficient pro/pre-B line, germ-line transcripts of the lambda J-C clusters, that are newly described here, became detectable 2 days later than their counterparts of J-C kappa. Clear differences could also be observed in vivo: germ-line transcripts of kappa were already present in large B220+ CD25+ pre B-II cells whereas germ-line lambda transcripts first became detectable at the consecutive developmental stage of small B220+ CD25+ pre-B-II cells. This activation pattern was found to be identical in mice which can not rearrange kappa due to a targeted deletion or inactivation of kappa. This suggests that pre-B-II cells follow a hit-and-run mechanism of development which includes programmed transitions and differential activation of the L chain loci, i.e. kappa first, then lambda. Thus, privileged activation of kappa might be the decisive factor in setting the 10:1 ratio of kappa to lambda present in the mouse.

B cells are programmed to activate κ and λ for rearrangement at consecutive developmental stages

B cells are programmed to activate κ and λ for rearrangement at consecutive developmental stages

Temporal and Spatial Patterns of Gene Expression for the Hatching Enzyme in the Teleost Embryo, Oryzias latipes

The hatching enzyme of the medaka, Oryzias latipes, consists of two proteases, high choriolytic enzyme (HCE) and low choriolytic enzyme (LCE). They are synthesized and accumulated in the same unicellular hatching glands and are secreted from them at the end of embryonic development to digest the egg envelope. Recently, these enzymes were purified, and their cDNA clones were isolated. In the present study, we examined temporal and spatial patterns of expression of the hatching enzyme genes during embryogenesis using cDNAs for HCE and LCE as probes. According to Northern blotting analysis, the expression of both genes started at the same time (stage 21-22 embryos: brain differentiation and lens formation) and the patterns of expression changed in parallel during development. In situ hybridization to whole embryo and the sections revealed that the expression of the HCE genes was detected first in the anterior end of the hypoblast layer in stage 16-17 (late gastrula) embryos. Distinct signals of the HCE gene expression were then detected in a group of cells located at the front of the head rudiment of embryos at stage 18-19 (1 somite). Treatment of the embryos with retinoic acid, which is known to affect the anterior differentiation of embryos, suppressed the hatching gland cell differentiation in accordance with the result of in situ hybridization. In stage 22 embryos, the HCE-positive cells dispersed in an ectodermal layer under the forebrain and optic vesicles. Thereafter, the hatching gland cells expressing the HCE mRNA were aligned along the branchial arches and finally rearranged to the inner wall of the pharyngeal cavity, following a marked elongation of the lower jaw. The results of in situ hybridization to whole embryos at consecutive developmental stages demonstrated that the hatching gland cells located at the most anterior portion of the hypoblast migrated posteriorward to endoderm (pharyngeal endoderm) by way of ectoderm, while they were expressing mRNA for the hatching enzyme. Retinoic acid treatment of embryos gave rise to aberrations in the final location of the hatching gland cells probably by disturbing their migration. Moreover, the number of hatching gland cells increased markedly during their migration. This fact strongly suggested a concurrence of gene expression and mitosis of a gland cell and/or a successive initiation of gene expression in maturing gland cells during migration.

Promoter region of mouse Tcrg genes.

The mouse T-cell receptor (Tcr){gamma} chain is characterized by a specific expression of V gene segments in the thymus corresponding to consecutive developmental stages; i.e., the Vg5 in fetal, Vg6 in neonatal, and Vg4 and Vg7 in adult. The order of the Vg gene usage correlates with the localization of the Vg gene segment on the chromosome; i.e., the Vg5 gene, being most proximal to the Jg1, is used first, followed by the Vg segments away from the Jg1 in a sequential manner. Since they all rearrange to the same Jg1 gene segment, the sequences in the coding region and/or in the 5{prime} upstream region are responsible for the stage-specific transcription. Also, Goldman and co-workers reported the germline transcription of Vg genes preceding their rearrangement. Therefore, the stage-specific transcription may be involved in the regulation of the stage-specific rearrangement; we sequenced and analyzed the 5{prime} flanking regions of the Vg5, Vg6, Vg4, and Vg7 genes to study the transcriptional relation. 18 refs., 2 figs., 1 tab.

Growth, composition and eating quality of Longissimus dorsi from young bulls fed the β-agonist cimaterol at consecutive developmental stages

The objective was to investigate the effect of the β-adrenergic agonist, cimaterol, on gain, composition and meat quality of primerib ( M. longissimus dorsi) from Friesian young bulls slaughtered at different developmental stages. Twelve pairs of monozygotic twins were allocated to three liveweight (LW) groups (162, 299 and 407 kg, respectively). Within each pair, one animal was given 0·056 mg cimaterol per kg LW for 90 days, while the other served as a control. Cimaterol treatment increased the estimated gain and the weight of primerib by 55 and 20%, respectively (both P < 0·001), and lean and protein content of the longissimus dorsi muscle by 26 and 25%, respectively (both P < 0·001), and concomitantly reduced fat content of primerib by 16% (P < 0·01) and intramuscular fat in longissimus dorsi by 36% (P < 0·001). Cimaterol treatment reduced total collagen content (P < 0·02), but not collagen solubility (P > 0·55). Meat colour was slightly lighter (lightness, P < 0·06), but pH 24 and pH final was not affected by cimaterol. Cimaterol increased Volodkevich shear force values (P < 0·001). In general, the effect of cimaterol on meat quality characteristics was evident in all three LW groups, and LW only affected percent fat in primerib, intramuscular fat content in longissimus dorsi, meat colour and absolute contents of protein, fat and bone.

Relationship between stock levels and the population structure of the Japanese anchovy

The anchovies distributed around Japan are only one species of Engraulis japonica Houttuyn although there are eight major species in the genus Engraulis in the world. Japanese anchovy stocks show considerable stability, fluctuating within a narrow range of 3–4 times, 1906–1984. This is in contrast to that of the Japanese sardine which shows fluctuations of up to 400 times. This phenomenon, together with the positive correlation found in abundance between consecutive developmental stages, makes it difficult to explain changes in abundance merely by chance or probability, in other words, by the “critical period”; concept The most important factor concerning mechanisms that stabilise stock levels is the population structure. Several local populations of the Japanese anchovy are dispersed geographically over a wide area, each of which is composed of various year classes and seasonal reproduction groups. The existence of these various groupings adapted to diverse environmental conditions maintains the stability of the overall stock. The second major factor is the existence of a population regulation mechanism that changes the reproduction mode and regulates the number of individuals in response to environmental conditions. In the 1950s to 1960s the stock level was maintained by spring spawnings of the large‐sized group. Since the end of the 1960s, the condition factor and maturity coefficient of the large‐sized group gradually decreased, their spawning activity in spring declined and the abundance of the large‐sized group also decreased. The decrease in abundance of the large‐sized group appeared to trigger or increase the spawning potential of the small‐sized group which spawns in summer‐autumn. Biological characteristics of the small‐sized group include relatively high spawning frequency and spawning batch fecundity compared with the large‐sized group, with shortened longevity. In this way, there are two types of reproduction modes, and the longevity, migration and maturing period of the anchovy change according to the reproduction mode. The Japanese anchovy skilfully adapted to its environment by changing its mode of life and population structure and a population regulation mechanism is working throughout the life of the species.

Development of congenital laryngeal atresias and clefts.

Congenital supraglottic laryngeal obstruction still is being described as subglottic stenosis. There are three clearly defined types of congenital laryngeal atresia, which result from arrest at consecutive developmental stages. Type 1 consists of a supraglottic obstruction, absent vestibule, and stenotic infraglottis, and type 2 is a supraglottic obstruction that separates a shallow primitive vestibule above from a nonstenotic infraglottis. These two types usually are accompanied by other defects, many of them severe. In type 3, a perforated membrane partly obstructs the glottis. Arrest of the dorsal advance of the chondrifying cricoid before the ends meet to form the dorsal lamina results in a complete laryngeal cleft, and incomplete fusion of the ends may leave a notch and/or foramen within the lamina. Failure of the interarytenoid tissue to develop will produce a local cleft, and maldevelopment of the cricoid cartilage or infraglottic submucosa can result in true subglottic stenosis without supraglottic obstruction.

Determination of Instar of the European Corn Borer (Lepidoptera: Pyralidae) Based on a Distribution Model of Head Capsule Widths

The European corn borer, Ostrinia nubilalis (Hubner), is a major pest of corn in France. Width of larval head capsules cannot be used directly to determine developmental stages of individuals because the ranges of measurements of two consecutive developmental stages overlap. A distribution model of head capsule widths of different instars, composed of five normal distributions, is fitted, and a discrimination method is proposed based on the probability of misclassification of larvae. Different infestation dates are compared during two years. Goodness-of-fit and assumptions are tested and criticized in relation to experimental conditions. It appears that statistical hypotheses are often not verified in field experiments, and that the validity of tests should be reconsidered. However, the model proposed is useful to criticize usual assumptions and to propose a practical solution.