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PubMed2005

Comparison of early development of three grasses: Lolium perenne, Agrostis stolonifera and Poa pratensis.

BACKGROUND AND AIMS: To improve the management of grass communities, early plant development was compared in three species with contrasting growth forms, a caespitose (Lolium perenne), a rhizomatous (Poa pratensis) and a caespitose-stoloniferous species (Agrostis stolonifera). METHODS: Isolated seedlings were grown in a glasshouse without trophic constraints for 37 d (761 degrees Cd). The appearance of leaves and their location on tillers were recorded. Leaf appearance rate (LAR) on the tillers and site-filling were calculated. Tillering was modelled based on the assumption that tiller number increases with the number of leaves produced on the seedling main stem. Above- and below-ground parts were harvested to compare biomass. KEY RESULTS: Lolium perenne and A. stolonifera expressed similar bunch-type developments. However, root biomass was approx. 30 % lower in A. stolonifera than in L. perenne. Poa pratensis was rhizomatous. Nevertheless, the ratio of above-ground : below-ground biomass of P. pratensis was similar to that of L. perenne. LAR was approximately equal to 0.30 leaf d(-1) in L. perenne, and on the main stem and first primary tillers of A. stolonifera. LAR on the other tillers of A. stolonifera was 30 % higher than on L. perenne. For P. pratensis, LAR was 30 % lower than on L. perenne, but the interval between the appearance of two successive shoots from rhizomes was 30 % higher than the interval between two successive leaf stages on the main stem. Above-ground parts of P. pratensis first grew slower than in the other species to the benefit of the rhizomes, whose development enhanced tiller production. CONCLUSIONS: Lolium perenne had the fastest tiller production at the earliest stages of seedling development. Agrostis stolonifera and P. pratensis compensated almost completely for the delay due to higher LAR on tillers or ramets compared with L. perenne. This study provides a basis for modelling plant development.

Agrostis↗
PubMed1989

Early development in the mouse: would it be affected by microgravity?

Gravity has been identified as a morphogenetic signal in Amphibian and bird embryonic development so it is plausible that it might be such in mammals as well. Since early mammalian development shows some apparently significant differences to these other groups, a brief summary of mouse embryogenesis will be given identifying events in which polarity is an important feature and consequently, in which gravity may be a causative factor. These include compaction and polarization during cleavage, establishment of the radial axis, the embryonic-abembryonic axis, the dorso-ventral axis, and the anterior-posterior axis, implantation, and the later rotation of the embryo. The experimental data on these morphogenetic steps will be discussed and an assessment of the possible involvement of gravity will be made.

Animals↗
PubMed2005

Early development of infants with untreated metopic craniosynostosis.

BACKGROUND: The purpose of this archival descriptive study was to examine the associations among craniosynostosis, perinatal risk factors or complications, and early cognitive development in infants diagnosed with craniosynostosis before they underwent surgery, to provide a greater empirical basis for surgical decision making and other early interventions. Specifically, it was hypothesized that there would be a greater number of infants with developmental delays than seen in the normative population. Furthermore, it was hypothesized that greater severity of synostosis would be correlated with lower cognitive and developmental scores. The secondary purpose of this study was to examine specific developmental domains such as language and motor skills in children with metopic craniosynostosis. METHODS: The research subjects for this retrospective cross-sectional study were a consecutive series of 22 infants diagnosed with metopic synostosis: 86 percent male, ages 3.6 to 25.3 months (mean +/- SD, 10.6 +/- 6.4 months). Mean gestational age was 38.8 (2.3) months, mean birth weight was 107.7 ounces, and 48.1 percent subsequently had craniovault reconstruction. Severity of craniosynostosis was assessed by a plastic surgeon (Buchman) and a neurosurgeon (Muraszko) and was confirmed radiographically by an independent rater (Angobaldo). Cognitive status was assessed with the Bayley Scales of Infant Development, Second Edition, at a mean age 11.6 (4.8) months. RESULTS: The mean Mental Development Index score for the sample was 96.0 (14.5), falling within the average range. Severity of synostosis was not significantly correlated with the overall Mental Development Index score. The mean language quotient for the sample was 77.3 (21.1). CONCLUSIONS: Despite suspicions that increased severity of deformity in infants with metopic craniosynostosis correlates with decreased cognitive and motor development, no such associations could be demonstrated. The results of this study did suggest, however, that children with isolated metopic craniosynostosis might show specific developmental delays in language acquisition. Finally, there were no significant correlations between cognitive development and prenatal risk factors.

Child, Preschool↗
PubMed1997

Turnover of histone acetyl groups during sea urchin early development is not required for histone, heat shock and actin gene transcription.

Histone acetylation is an extremely complex, reversible and specific process. In order to evaluate the importance of this modification for gene expression during sea urchin development, acetyl group turnover of histone lysine residues was blocked by sodium butyrate. The continuous presence of 15 Mm sodium butyrate in the incubation medium from the onset of development blocked gastrulation and resulted in chromatin containing hyperacetylated histone molecules in amounts usually not found in nature. At the mesenchyme blastula stage, the expression of the early histone genes was shut off and the expression of the late genes was switched on both in control and sodium butyrate-treated embryos. Investigation of the early histone gene chromatin structure in butyrate-treated embryos revealed a random distribution of nucleosomes when the genes were transcriptionally active as compared to regular nucleosomal packaging when genes were inactive. These changes in chromatin structure during development mimicked the chromatin structural transition of the early histone genes in control embryos. In addition, the ability of heat shock genes to be induced at elevated temperature and repressed at normal temperature was unaffected in butyrate treatment of embryos. Finally, the developmental profiles of the cytoskeletal CyIIIa actin gene expression in control and butyrate-treated embryos were very similar. The data presented suggest that turnover of histone acetyl groups and the overall level of histone acetylation are not determining factors in the up and down regulation of a number of genes during early development of sea urchin.

Acetylation↗
PubMed2005

Human embryonic stem cells as a model for studying epigenetic regulation during early development.

In order to exploit the exceptional potential of human embryonic stem cells (hESCs) in cell-replacement therapies, the genetic and epigenetic factors controlling early human development must be better defined. Limitations in human embryonic material restrict the scale of studies that can be performed, and therefore an in vitro model in which to study epigenetic regulation in human preimplantation cell types would be desirable. HESCs could provide such a model, but since they are derived from a stage in mammalian development when the genome is undergoing global epigenetic remodelling, it is unclear whether their epigenetic status would be stable or subject to variation. Herein, we discuss recent work that examines allele-specific imprinted gene expression and methylation patterns, thereby demonstrating that hESCs maintain a substantial degree of epigenetic stability during culture. Therefore, we suggest that hESCs could provide a model for studying epigenetic regulation during the early stages of human cellular pluripotency and differentiation. Furthermore, we propose specific experiments using such a model to address important questions pertaining to epigenetic mechanisms of certain human disorders.

Animals↗
PubMed2002

REM sleep and the early development of posttraumatic stress disorder.

OBJECTIVE: The potential for chronicity and treatment resistance once posttraumatic stress disorder (PTSD) has become established has stimulated interest in understanding the early pathogenesis of the disorder. Arousal regulation and memory consolidation appear to be important in determining the development of PTSD; both are functions of sleep. Sleep findings from patients with chronic PTSD are complex and somewhat contradictory, and data from the acute phase are quite limited. The aim of the present study was to obtain polysomnographic recordings during an acute period after life-threatening experiences and injury and to relate measures of sleep duration and maintenance and the timing, intensity, and continuity of REM sleep to the early development of PTSD. METHOD: Twenty-one injured subjects meeting study criteria received at least one polysomnographic recording close to the time of medical/surgical stabilization and within a month of injury. PTSD symptoms were assessed concurrently and 6 weeks later. Sleep measures were compared among injured subjects with and without significant PTSD symptoms at follow-up and 10 noninjured comparison subjects and were also correlated with PTSD severity. RESULTS: There was more wake time after the onset of sleep in injured, trauma-exposed patients than in noninjured comparison subjects. Development of PTSD symptoms was associated with shorter average duration of REM sleep before a stage change and more periods of REM sleep. CONCLUSIONS: The development of PTSD symptoms after traumatic injury is associated with a more fragmented pattern of REM sleep.

Acute Disease↗
PubMed1988

Chronic illness and early development. The parent's perspective.

While many chronic illnesses are diagnosed in infancy, there is little systematic study of the impact of chronic illness on early social development and how parental adjustment to a chronically ill infant contributes to subsequent outcomes. This paper outlines some of the factors which affect parents' ability to care for chronically ill infants and preschoolers. It draws upon studies of infants with other medical problems, ongoing longitudinal study of infants with cystic fibrosis and congenital heart disease by the authors; and the authors' clinical experience.

Child↗
PubMed2006

The expression of cell proliferation-related genes in early developing flowers is affected by a fruit load reduction in tomato plants.

Changes in photoassimilate partitioning between source and sink organs significantly affect fruit development and size. In this study, a comparison was made of tomato plants (Solanum lycopersicum L.) grown under a low fruit load (one fruit per truss, L1 plants) and under a standard fruit load (five fruits per truss, L5 plants), at morphological, biochemical, and molecular levels. Fruit load reduction resulted in increased photoassimilate availability in the plant and in increased growth rates in all plant organs analysed (root, stem, leaf, flower, and fruit). Larger flower and fruit size in L1 plants were correlated with higher cell number in the pre-anthesis ovary. This was probably due to the acceleration of the flower growth rate since other flower developmental parameters (schedule and time-course) remained otherwise unaffected. Using RT-PCR, it was shown that the transcript levels of CYCB2;1 (cyclin) and CDKB2;1 (cyclin-dependent kinase), two mitosis-specific genes, strongly increased early in developing flower buds. Remarkably, the transcript abundance of CYCD3;1, a D-type cyclin potentially involved in cell cycle regulation in response to mitogenic signals, also increased by more than 5-fold at very early stages of L1 flower development. By contrast, transcripts from fw2.2, a putative negative regulator of cell division in tomato fruit, strongly decreased in developing flower bud, as confirmed by in situ hybridization studies. Taken together, these results suggest that changes in carbohydrate partitioning could control fruit size through the regulation of cell proliferation-related genes at very early stages of flower development.

Cell Cycle Proteins↗
PubMed2003

Early development of multiple epithelial neoplasms in Netherton syndrome.

We report a case of Netherton syndrome manifested as congenital ichthyosiform erythroderma, trichorrhexis invaginata and atopy, who in early adulthood developed multiple, aggressive epithelial neoplasms in sun-exposed areas of the skin, in areas with papillomatous skin hyperplasia and at the left parotid region. The occurrence of cutaneous neoplasia has been reported in syndromes with congenital ichthyosis and suggests that the underlying genetic defects may cause the development of cancer in prone patients.

Adult↗
PubMed1999

Organization of early development by calcium patterns.

This survey focuses on early or primitive developmental phenomena for which the location of a steady high calcium region or the direction of a calcium wave is critical and calcium is more than a trigger. It starts with the long studied roles of calcium in fucoid eggs and in Dictyostelium and progresses to newer work on high calcium regions in medaka fish, zebrafish, and Drosophila eggs. It then proposes that propagated, ultraslow developmental waves in six diverse systems indicate a new and important class of calcium waves. These include the morphogenetic furrow in Drosophila eye discs, floret formation in sunflowers, DNA replication waves in protozoan macronuclei, growth-cone like waves in hippocampal neurons, and two others. It then considers the possible organizing roles of slow calcium waves. Here, it emphasizes surface contractile waves during primary neural induction and elsewhere as well as the possibility of cellular peristalsis. Finally, it reviews the organizing roles of fast calcium waves in ascidian eggs.

Animals↗
PubMed1985

Cell surface glycoproteins mediate compaction, trophoblast attachment, and endoderm formation during early mouse development.

Early mouse embryos undergo several morphogenetic processes, such as compaction, trophoblast attachment, and endoderm formation that can be studied in vitro. Several polyspecific and monospecific antisera have been used to perturb these processes in a nontoxic, reversible fashion. One of the antibody-defined molecules, cell CAM 120/80, promotes epithelial cell adhesion, embryo compaction, and endoderm formation. The results suggest the presence of another such molecule(s) involved in these same processes. Evidence is also presented that another set of antibody-defined molecules, GP 140, involved in attachment of somatic cells to the substrate, mediates trophoblast attachment of the mouse blastocyst. The possible role of these molecules in governing the processes leading to cell lineages in the mouse embryo is discussed.

Animals↗
PubMed1997

Ouabain sensitivity and expression of Na/K-ATPase alpha- and beta-subunit isoform genes during bovine early development.

The fluid movements that arise during blastocyst formation (cavitation) are, at least in part, driven by the Na/K-ATPase. In this study, the reverse transcriptase-polymerase chain reaction (RT-PCR) was used to survey bovine pre-attachment embryos for transcripts encoding known isoforms of the Na/K-ATPase alpha- and beta-subunits, including isoforms not previously detected during the first week of mammalian development. Transcripts encoding the Na-K-ATPase alpha 1, alpha 2, alpha 3 and beta 2 isoforms were detected throughout bovine preattachment development. This is the first indication that alpha 2, alpha 3 and beta 2 mRNAs are expressed during this early developmental interval. As in the mouse, beta 1-subunit transcripts were not detected until the morula stage and were also present in blastocysts. Thus, in two mammalian species an increase in abundance of beta 1 isoform transcripts in the morula stage is coincident with the onset of cavitation. Transcripts encoding the recently characterized alpha 4 isoform were not detected. The sensitivity of bovine blastocysts to ouabain (a potent inhibitor of Na/K-ATPase) was determined by assessing the ability of bovine blastocysts to recover in ouabain supplemental culture medium following cytochalasin-induced blastocyst collapse. Re-expansion of bovine blastocysts was inhibited in all ouabain concentrations down to 10(-9) M. Mouse blastocysts, in contrast, were sensitive to ouabain at or above 10(-3)M. These results have established that transcripts encoding multiple isoforms of both the alpha and beta subunits of the Na/K-ATPase are expressed throughout early bovine development and that bovine blastocysts display a greater sensitivity to ouabain than murine blastocysts. Future analysis will determine the possible individual and collective roles of these isoforms during blastocyst formation.

Animals↗
PubMed2001

Selective expression of the small GTPase RhoB in the early developing mouse lens.

This report describes the expression and distribution pattern of RhoB GTPase in the developing mouse lens. RhoB expression was confirmed by sequencing an reverse transcriptase-polymerase chain reaction-generated DNA fragment of RhoB. Immunohistochemical analysis of RhoB revealed expression in the lens vesicle (both anterior and posterior vesicle) at embryonic day (E) 11.5, and in the epithelium and primary fibers of the E14.5 lens. Compared with the neonatal stage (day 1), where RhoB is detected in the entire lens (epithelium, primary, and secondary fibers), expression of this protein is restricted to the epithelial and outer cortical secondary fibers in postnatal lenses (from day 7 to day18). Interestingly, in E11.5 and E14.5 lenses, RhoB is localized predominantly in the lens, but not detectable in the retina, cornea, or other ocular tissues. RhoB expression appears to be down-regulated in the postnatal lens with concomitant up-regulation in the retina and cornea, compared with earlier stages of development (eyes of E11.5, E14.5, and neonatal mice). This study reveals the selective expression of RhoB in the lens during early eye development and suggests a potential role for this small GTPase in cytoskeletal reorganization associated with lens epithelial cell elongation and differentiation.

Animals↗
PubMed2002

Early development of neuronal hypothalamic thermosensitivity in birds: influence of epigenetic temperature adaptation.

The aim of the study was to investigate the prenatal influence of different incubation temperatures on the early postnatal development of neuronal hypothalamic thermosensitivity in birds. The experiments were carried out in brain slices of 1-, 5- and 10-days-old Muscovy ducklings incubated at 35, 37.5 (control) or 38.5 degrees C during the last week of incubation. Firing rate of neuronal activity was recorded extracellularly during sinusoidal temperature changes. The results show that the temperature experienced prenatally has a clear influence on postnatal neuronal hypothalamic thermosensitivity. For instance, at the 10th day post-hatching, exposure to the cooler prenatal incubation temperature resulted in elevated neuronal hypothalamic warm sensitivity through an increased proportion of warm sensitive neurons and a reduced proportion of cold sensitive neurons in comparison with the control group. Exposure to the warmer prenatal incubation temperature induced the opposite effect. In these age group changes in neuronal hypothalamic thermosensitivity occur in relation to the prenatal temperature experienced (proximate adaptive). During the first days of life, prenatal temperature load induced a significant change in the thermosensitivity of hypothalamic neurons which was independent of the direction of change in incubation temperature in comparison with control conditions (proximate non-adaptive). Changes in the thermosensitivity of hypothalamic neurons after prenatal temperature experiences observed in all age groups may be the result of epigenetic temperature adaptation.

Adaptation, Physiological↗
PubMed1992

The regulation of translation by the 5' untranslated region of Xenopus c-myc I mRNA during early development.

The translational efficiency of chloramphenicol acetyltransferase (CAT) mRNA containing 5' untranslated region (UTR) sequences of Xenopus c-myc I mRNA was examined in the Xenopus oocyte and early embryo. In contrast to their reduced translation in the oocyte, CAT mRNAs containing 5' UTR sequences located between the c-myc I P0 and P2 promoters translate as efficiently as CAT mRNA controls when injected into early embryos. This pattern of differential regulation of c-myc I translation is similar to that observed for mouse c-myc 5' UTR-containing CAT transcripts during Xenopus oogenesis and early embryogenesis [Lazarus, P., Parkin, N. & Sonenberg, N. (1988). Oncogene, 3, 517-521]. Oocyte-specific translational inhibition was not observed for CAT mRNAs containing c-myc I 5' UTR sequences located 3' of the P2 promoter. No significant alteration in c-myc I 5' UTR/CAT mRNA stability was observed in the oocyte as compared with CAT mRNA controls. The significance of this promoter-dependent translational regulation with respect to c-myc expression and early Xenopus development is discussed.

Animals↗
PubMed2004

Genetic networks in the early development of Caenorhabditis elegans.

One of the best-studied model organisms in biology is Caenorhabditis elegans. Because of its simple architecture and other biological advantages, considerable data have been collected about the regulation of its development. In this review, currently available data concerning the early phase of embryonic development are presented in the form of genetic networks. We performed computer simulations of regulatory mechanisms in embryonic development, and the results are described and compared with experimental observations.

Animals↗
PubMed2001

Inhibitory effect of interleukin 3 on early development of human B-lymphopoiesis.

Interleukin 3 (IL-3) is known as a stimulator of proliferation and differentiation of non-lymphoid cells, but information about the activity of IL-3 in lymphopoiesis is limited. In the present study, we examined the effect of IL-3 on human B-lymphopoiesis using the co-culture system on a murine stromal cell line, MS-5, with stem cell factor (SCF) and granulocyte colony-stimulating factor (G-CSF). Although a large number of CD45+CD19+ B cells were generated in the co-culture of cord blood CD34+ cells, the addition of IL-3 to the co-culture suppressed the B-cell generation in a dose-dependent manner. In the co-culture, CD34+IL-3 receptor alpha-chain (IL-3Ralpha)+ cells, but not IL-3Ralpha- cells, produced B cells, and IL-3 suppressed the B-cell generation from CD34+IL-3Ralpha+ cells, suggesting that IL-3 exerts an inhibitory effect through the binding to IL-3Ralpha on CD34+ cells. Because the delayed addition of IL-3 and the short-term exposure to IL-3 showed that IL-3 acted as an inhibitor at an early stage of B-cell development from CD34+ cells, before the generation of CD19+ B cells, the effect of IL-3 on the early development of B cells from immature CD34+CD38- cells was examined. Individual colonies, produced from clone-sorted CD34+CD38- cells by SCF, thrombopoietin and a complex of IL-6/soluble IL-6R with or without IL-3, were divided into two fractions and analysed for B-cell potential using co-culture on MS-5 with SCF and G-CSF, and haematopoietic potential using methylcellulose clonal culture. Although some colonies cultured without IL-3 showed both B-cell and haematopoietic potential, all the colonies cultured with IL-3 showed only haematopoietic potential. These results indicate that IL-3 has an inhibitory effect on the B-cell generation from human lymphohaematopoietic progenitor cells.

Animals↗