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Results for “Growth and Development”

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At least 145 records · Page 8Linked to original sources
PubMed2006

Dehydroascorbate reductase affects leaf growth, development, and function.

Ascorbic acid (Asc) is a major antioxidant in plants that detoxifies reactive oxygen species (ROS) and maintains photosynthetic function. Expression of dehydroascorbate reductase (DHAR), responsible for regenerating Asc from an oxidized state, regulates the cellular Asc redox state, which in turn affects cell responsiveness and tolerance to environmental ROS. Because of its role in Asc recycling, we examined whether DHAR is important for plant growth. Suppression of DHAR expression resulted in a preferential loss of chlorophyll a, a lower steady state of Rubisco as measured by the amount of the large subunit of Rubisco (RbcL), and a lower rate of CO(2) assimilation. As a consequence, a slower rate of leaf expansion and reduced foliar dry weight were observed. In addition, an accelerated rate of loss of chlorophyll, RbcL, light-harvesting complex II, and photosynthetic functioning was observed in mature leaves, resulting in premature leaf aging. Reduced growth rate as measured by plant height and leaf number was consistent with the DHAR-mediated reduction of photosynthetic function. Increasing DHAR expression maintained higher levels of chlorophyll, RbcL, light-harvesting complex II, and photosynthetic functioning, resulting in delayed leaf aging. The effect of DHAR expression on leaf aging inversely correlated with the level of lipid peroxidation, indicating that DHAR functions to protect against ROS-mediated damage. These observations support the conclusion that through its Asc recycling function, DHAR affects the level of foliar ROS and photosynthetic activity during leaf development and as a consequence, influences the rate of plant growth and leaf aging.

Ascorbic Acid↗
PubMed1998

Distinct molecular phenotypes in murine cardiac muscle development, growth, and hypertrophy.

The onset of cardiac hypertrophy is associated with characteristic changes in myocardial gene expression that are thought to recapitulate a developmental gene program. We report here the first gene expression profile of the murine myocardium, using a rapid method of quantitative expression analysis based on real-time analytical RT-PCR. This assay was used to measure expression levels of 29 genes in (1) late stage development as represented by day 1 neonatal ventricles, (2) normal cardiac growth in 3 and 18 month old mice, and (3) cardiac hypertrophy following pressure overload by aortic constriction. For males and females normal growth is not associated with differential expression although there is elevated expression of skeletal and smooth muscle actin mRNA's in males compared to females. Using normal adult ventricles as a reference, there are many qualitative and quantitative differences between the day 1 neonatal myocardium and experimental cardiac hypertrophy. These data suggest that the response to POL involves a subset of re-expressed developmental genes together with altered expression of genes not necessarily associated with cardiac development.

Animals↗
PubMedDate not supplied

The interactive role of mucosal T lymphocytes in intestinal growth, development and enteropathy.

Over the past 15-20 years, research has progressively focused on the mucosal T cell as the central factor in the initiation of physiological or pathological changes, first in the growth and maturation of the early (postnatal) intestine, and second in adult-type enteropathies resulting from sensitivity to either food or pathogen-derived antigens. T cell-mediated events may be measured, for example, in terms of specific immunopathologic patterns of change and injury, such as type 1 (lymphocyte infiltration), type 2 (crypt hyperplasia) and type 3 (flat-destructive), which can be recognized and quantitated microscopically; by determination of lymphocyte reactivity through secretion of interleukin-2 receptors (IL-2R) into plasma or expression by mucosal lymphocytes; by quantitation of lymphocyte subsets emigrating into inflamed tissues by immunoperoxidase-labelled monoclonal antibodies; or by the determination of T cell receptor polymorphisms. Alterations in intestinal growth, structure and function at weaning are likely to be T cell-mediated as they are analogous to the same type 1/2 lesions that reflect modulation of adult mucosal architecture in food and parasite-induced hypersensitivity reactions. Enteropathies associated with HIV infection and T cell deficiency display a milder degree of villous flattening and impaired crypt hyperplasia than that typical of gluten-sensitivity, suggesting a reversion to lesser degrees of mucosal pathology (type 1/2). Clearly more information will accrue; meanwhile the remarks in this brief survey should provide a firm basis whereby clinician and scientist can meet, and together recognize and further dissect the modulatory effect of T lymphocytes on mucosal structure and function.

Animals↗
PubMed1996

Pre- and postembryonic development, growth and turnover of olfactory receptor neurones in crayfish antennules

The antennules of the crayfish Cherax destructor can first be observed as antero-laterally located lobes in embryos that have reached the 50 % stage of development. Clusters of cells that are probably the olfactory receptor neurones (ORNs) appear at the distal end of these lobes, which later differentiate into the lateral flagella of the antennules. New clusters of ORNs and segments are added at the proximal end of the lateral flagellum throughout the postembryonic stages and well into the juvenile adult stage. From a comparison of the exuvia and the newly emerged flagella in animals over a wide range of sizes, we conclude that, once the animals reach a certain size (approximately 7 mm carapace length), the most distal, and oldest, segments of the antennule are shed. Growth occurs from the proximal end of the flagellum, and the addition of new ORNs is the result of a delayed differentiation of the flagellar segments that takes place at the proximal end of the chemoreceptor array, about halfway along the flagellum.

Journal Article↗
PubMed2006

Spatiotemporal distribution of heparan sulfate epitopes during murine cartilage growth plate development.

Heparan sulfate proteoglycans (HSPGs) are abundant in the pericellular matrix of both developing and mature cartilage. Increasing evidence suggests the action of numerous chondroregulatory molecules depends on HSPGs. In addition to specific functions attributed to their core protein, the complexity of heparan sulfate (HS) synthesis provides extraordinary structural and functional heterogeneity. Understanding the interactions of chondroregulatory molecules with HSPGs and their subsequent outcomes has been limited by the absence of a detailed analysis of HS species in cartilage. In this study, we characterize the distribution and variety of HS species in developing cartilage of normal mice. Cryo-sections of femur and tibia from normal mouse embryos were evaluated using immunostaining techniques. A panel of unique phage display antibodies specific to particular HS species were employed and visualized with secondary antibodies conjugated to Alexa-fluor dyes. Confocal microscopy demonstrates that HS species are dynamic structures within developing growth plate cartilage and the perichondrium. GlcNS6S-IdoUA2S-GlcNS6S species are down regulated and localization of GlcNS6S-IdoUA-GlcNS6S species within the hypertrophic zone of the growth plate is lost during normal development. Regional differences in HS structures are present within developing growth plates, implying that interactions with and responses to HS-binding proteins also may display regional specialization.

Animals↗
PubMed1978

Growth, development, and site location of the trematode Himasthla quissetensis in the chick following cloacal drop infections with cercariae.

Infections with Himasthla quissentensis were obtained per cloaca in the domestic chick using cercariae. Worms showed a preference for the ileum where they grew and developed to maturity at a rate comparable to those raised in the gull (Stunkard, 1938). Those from the bursa of Fabricius showed relatively little growth and exhibited gonadal atrophy in some instances.

Age Factors↗
PubMed1975

Protein synthesis, development, growth and life span.

To test the hypothesis that reduced protein synthesis may increase life span by retarding genetic informational transfer during early life and reducing the use of the genetic code and thereby minimizing genetic imperfections as they may occur during late life, two approaches were used. In the first protein synthesis was depressed by the administration of cycloheximide, in the second by reducing the dietary protein level. One-day-old chick embryos were injected with either 0.8 gamma or 1.0 gamma of cycloheximide. On the second and third day of incubation both stage of development and heart rate were lower in the treated embryos. Growth was retarded throughout the 17 days of incubation as measured by size and DNA contents. As estimated by the activities of various enzymes per unit DNA, cells of the treated embryos were the same as normal ones of the same age. Sixteen-month-old female Wistar rats which had been previously maintained on a commercial diet (23.4% protein) were fed diets which contained either 24, 12, 8 or 4% casein throughout their remaining life span. Except for a lowering of the body weights of the animals fed the 4% casein diet, the body weights of the remaining animals were unchanged. Reducing the dietary protein level from 24% to 12% increased the life span (25%) of the animals.

Animals↗
PubMed1981

[Determination of skeletal age in children of Western Germany with normal and abnormal growth development].

The most important methods for the determination of skeletal age according to Greulich and Pyle (1959) and Tanner et al. (1975) were tested for their applicability to West-German children. The validity of both methods was good with an intra- and interobserver error between 1,8 and 4,7 months. The practicability of both methods however was different, on average it takes 2--3 minutes for the Greulich-Pyle-inspection-method, whereas the Tanner-20-B-method required 8--9 minutes. The Tanner-20-B-method had to be corrected only for 6--10 years old girls, whereas the Greulich-Pyle-bone-specific-method required correction factors for all age groups from 2--16 years. Both, the Greulich-Pyle-and the Tanner-method can be recommended for use in West-Germany children when the described correction tables are applied. Also in children with abnormal growth both methods may be used without systemic error. However the cause of growth disturbance has to be taken into consideration for the individual case.

Adolescent↗
PubMed2004

Nerve development, growth and differentiation during regeneration in Enchytraeus fragmentosus and Stylaria lacustris (Oligochaeta).

Enchytraeus fragmentosus (Enchytraeidae) and Stylaria lacustris (Naididae) are small terrestrial and limnetic oligochaetes that exclusively or seasonally reproduce by fragmentation and regeneration, respectively. We traced the neuronal development and differentiation during regeneration in order to gain information on the basic organization and evolution of the oligochaete nervous system. Subsequent to artificial amputation, the nervous systems have been stained with antibodies directed against acetylated alpha-tubulin. The staining was analyzed by indirect fluorescence in combination with confocal laser scanning microscopy. Both species show unique oligochaete neuronal regeneration patterns: (i) numerous fibers branch off from segmental nerves near the wound site and innervate the blastema; and (ii) the ventral cord is partly reestablished before the circumesophageal connectives develop. In the investigated 'Oligochaeta' the outgrowing fibers of the ventral nerve cord are soon bundled into at least two distinct connective pairs, which prolong into dorsal and ventral roots next to the mouth. Subsequent complete fusion of the doubled roots forms simple connectives. Thus, dorsal roots are not a unique feature for 'Polychaeta'. They occur as a transient structure in 'Oligochaeta' and might be part of the neuronal ground pattern of Annelida. The initially tetra or even pentaneuronal ventral nerve cord also differentiates into an unineuronal one by fusion.

Animals↗