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Results for “Body Patterning”

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PubMed1993

The torso receptor localizes as well as transduces the spatial signal specifying terminal body pattern in Drosophila.

Specification of the end portions of the Drosophila body depends on the torso (tor) protein, a receptor tyrosine kinase that accumulates uniformly along the entire surface of the embryo but is activated only in the vicinity of the poles. Several genes are normally required for activating tor and appear to define a system in which a gene product tethered to the extracellular vitelline membrane at each end of the egg provides a local source for an extracellular tor ligand. This ligand would have to diffuse from the membrane to the cell surface of the embryo without losing its spatial localization. Here we report that the failure to accumulate tor protein at one or both poles leads to spatially inappropriate activity of more centrally located receptor. This ectopic activity depends on the same gene functions normally required for activating tor; thus we infer that it reflects inappropriate diffusion of the ligand to more central regions of the body. We conclude that the receptor not only transduces the spatial signal imparted by the tor ligand, but also ensures its correct localization by sequestering the ligand. Ligand trapping by receptor may also localize spatial signals in other patterning systems, including specification of the dorsal-ventral axis in Drosophila and of vulval cell fates in Caenorhabditis elegans.

Animals↗
PubMed2005

Modulating Hox gene functions during animal body patterning.

With their power to shape animal morphology, few genes have captured the imagination of biologists as the evolutionarily conserved members of the Hox clusters have done. Recent research has provided new insight into how Hox proteins cause morphological diversity at the organismal and evolutionary levels. Furthermore, an expanding collection of sequences that are directly regulated by Hox proteins provides information on the specificity of target-gene activation, which might allow the successful prediction of novel Hox-response genes. Finally, the recent discovery of microRNA genes within the Hox gene clusters indicates yet another level of control by Hox genes in development and evolution.

Animals↗
PubMed2001

Mesoderm formation in Eleutherodactylus coqui: body patterning in a frog with a large egg.

The direct developing frog, Eleutherodactylus coqui, develops from a large egg (diameter 3.5 mm). To investigate the effect of egg size on germ-layer formation, we studied mesoderm formation in E. coqui and compared it to that of Xenopus laevis (diameter 1.3 mm). First, we identified the position of prospective mesoderm in the 16-cell E. coqui embryo by cell-lineage tracing. Although the animal blastomeres are small, they form most of the blastocoel roof and make extensive contributions to some mesodermal tissues. Second, we performed recombinant analysis with X. laevis animal caps to define the distribution of mesoderm-inducing activity. Mesoderm-inducing activity in E. coqui was restricted around the marginal zone with strong activity in the superficial cells. Neither the vegetal pole nor the blastocoel floor had activity, although these same regions from X. laevis induced mesoderm. Third, we cloned Ecbra, a homologue of Xbra, an early mesoderm marker in X. laevis. Ecbra was expressed in the marginal ring close to the surface, similar to X. laevis, but E. coqui had weaker expression on the dorsal side. Our results suggest that mesoderm formation is shifted more animally and superficially in E. coqui compared to X. laevis.

Animals↗
PubMed1997

Nutrient intake patterns, body mass index, and vitamin levels in patients with rheumatoid arthritis.

OBJECTIVE: To assess nutrient intakes and vitamin levels in 79 patients with rheumatoid arthritis participating in a trial and to determine whether changes in body mass index were associated with changes in disease activity. METHODS: This study evaluated baseline vitamin levels, 1-day dietary intakes, and weight every 3 months for 1 year. Linear regression analysis was used to evaluate the relationship of time to body mass index. Analysis of covariance was used to determine if body mass index, time, or treatment had an effect on disease activity. RESULTS: Deficient vitamin levels and poor nutrient intake patterns were prevalent in the study population. Changes in body mass index over time did not correlate with changes in disease activity. CONCLUSIONS: Rheumatoid arthritis patients are at high risk of obesity, abnormal vitamin levels, and poor nutrient intakes. Changes in body mass index failed to correlate with changes in disease activity.

Arthritis, Rheumatoid↗
PubMed1985

Dynamics of the control of body pattern in the development of Xenopus laevis. II. Timing and pattern in the development of single blastomeres (presumptive lateral halves) isolated at the 2-cell stage.

Xenopus embryos have been selected in which the first cleavage plane is tending strongly to correspond with that of bilateral symmetry for the future larval pattern. The two blastomeres produced by this cleavage have been separated and allowed to develop as reciprocal pairs of presumptive lateral-half isolates. The early development and the time course of the gastrulation movements, and the qualitative and quantitative aspects of larval mesodermal patterns, have been studied in relation to synchronously fertilized controls. The result is restoration of bilateral symmetry for developmental potential, and production of a pair of small gastrulae and larvae with qualitatively complete body plans but 50% of control cell numbers each (see Kageura & Yamana, 1983). Most commonly, however, the resulting small patterns deviate from the normal range in their proportions in at least one of two ways. The notochord territory is rarely, if ever, under-represented (i.e. notochords contain at least 50% control cell numbers) but it is frequently over-represented, in some cases approximating that of control whole embryos. Reciprocal pairs of isolates thus tend, on average, to produce more notochordal tissue than they would have if developing normally. Secondly, the balance of cell population sizes assigned to somites up and down the axis is altered so that relatively anterior members of the series are less scaled down than those in trunk and tail regions. The mesodermal plan developed by a lateral-half isolate is thus characteristically intermediate between that of a small, harmonious larva (the proportional presumptive fates of the materials, apart from loss of bilaterality), and that of the mosaically developing presumptive dorsoanterior cell pair from the 4-cell stage, discussed in the previous paper. A minority of the lateral isolates does develop a harmonious and thus well-regulated body plan, however, and the normality or otherwise of the schedules of gastrulation timing in isolates seems a good predictor of their morphogenetic performance in this respect. The results are discussed as informing us about the dynamics of the interactions, prior to gastrular stages, that underlie the normal mesoderm development.

Animals↗
PubMed2004

Predictive value of menstrual cycle pattern, body mass index, hormone levels and polycystic ovaries at age 15 years for oligo-amenorrhoea at age 18 years.

BACKGROUND: On the question of how to counsel adolescents with irregular menstrual cycles or oligomenorrhoea, no clear answer has been given. Adolescents with oligomenorrhoea especially show endocrine abnormalities and may be at risk for ovulatory dysfunction and the polycystic ovary syndrome in adulthood. METHODS: We followed a cohort of adolescents to document changes in menstrual cycle pattern between ages 15 and 18 years in the general population. RESULTS: Two per cent (2/128) of adolescents with regular menstrual cycles developed oligomenorrhoea, and 12% (17/148) of those with irregular menstrual cycles did so. Fifty-one per cent (34/67) of the oligomenorrhoeic adolescents remained oligomenorrhoeic. Increase in body mass index (BMI), concentration of LH, androstenedione or testosterone, and polycystic ovaries (PCO) were associated with persistence of oligomenorrhoea. In multivariate analysis only a normal to high BMI (>19.6 kg/m(2)) consistently contributed significantly to predict persistent oligomenorrhoea. Glucose:insulin ratio as a marker for insulin resistance was not associated with an increased risk for oligomenorrhoea. CONCLUSIONS: Oligomenorrhoea at age 18 years is better predicted by menstrual cycle pattern at age 15 years than by LH or androgen concentrations or PCO at this age. Not only obese, but also normal weight oligomenorrhoeic, adolescents have a high risk of remaining oligomenorrhoeic.

Adolescent↗
PubMed1997

Disordered eating patterns, body image, self-esteem, and physical activity in preadolescent school children.

OBJECTIVE: Eating disorders have been typically defined as an "adolescent problem." As a result of emerging evidence which indicated this health problem to be evident in the prepubescent age range, this study aimed to establish prevalence and factors associated with eating/dieting, physical activity, and body image among a nonclinical, naturalistically-derived sample of preadolescent (aged 10 and 11) school children (n = 61). METHOD: This cohort of children, which represented the entire grade 6 class of a suburban Elementary school, was measured for body image satisfaction [silhouettes], a participation in activity index, a self-worth scale and a measure of eating attitudes & behavior [Eating and Me scale [E & M]]. RESULTS: The longitudinal assessment of body image [3 measures over 9 months] indicated signs of stability of "actual" assessments of body image for males, but marked changes for females who preferred to be ideally "chunkier" in stature over time. Physical activity was only implicated with bulimia for the male sub-group. The E & M scale reported a Cronbach's alpha of .76, with two factors [bulimia; drive for thinness/anorexia] representing 65% of the total variance. Moderate internal validity [r .58] between body dissatisfaction on the E & M scale and the silhouette measure was observed. DISCUSSION: These results demonstrated that body image views and concerns appeared before puberty, that gender differences prevailed with respect to eating/dieting, activity and body image, and that the E & M scale has emerged as a promising research tool. The longitudinal nature of this study of eating disorders also promotes the need for qualitative research methodology and attention to pre-pubertal cognitive/perceptual processes.

Anorexia↗
PubMed1984

The effect of liver denervation on meal patterns, body weight and body composition of rats.

Neural liver glucoreceptors have been proposed as a primary controller of food intake (FI). Male Sprague-Dawley rats were either sham operated or liver denervated (LD). LD rats had all tissue cut between the liver and the esophagus, stomach and upper 1 cm of the duodenum. The hepatic artery and surrounding tissue were also removed. Finally the hepatic portal vein and the bile duct were stripped clean and the former phenol treated. Three days after surgery animals were placed in modules for continuous computer monitoring of feeding behavior. At no time after surgery did the daily food intake or body weight of the groups differ significantly. Meal size and frequency (light-dark distribution) were determined for 6 days and averaged. Neither parameter was altered by LD. During the next 6 months food intake and body weights of the groups did not differ significantly. At sacrifice, body composition was directly determined with no significant differences observed between LD and sham operated rats. LD were confirmed histologically. Monoamine histofluorescence of the livers of rats subjected to liver denervation revealed an absence of the normal fluorescence seen on small blood vessels in liver parenchyma of sham operated rats. The data do not support the concept that liver glucoreceptors are a major controller of FI.

Animals↗
PubMed1991

RNA regulatory elements mediate control of Drosophila body pattern by the posterior morphogen nanos.

In Drosophila embryos, graded activity of the posterior determinant nanos (nos) generates abdominal segmentation by blocking protein expression from maternal transcripts of the hunchback (hb) gene. When active inappropriately at the anterior pole, nos can also block expression of the anterior determinant bicoid (bcd). We show that both regulatory interactions are mediated by similar sequences in the 3' untranslated region of each transcript. These nos response elements (NREs) are both necessary and sufficient to confer nos-dependent regulation, the degree of regulation determined by the number and quality of the elements and the level of nos in vivo. Based on these and other results, we argue that nos acts as a morphogen, controlling hb expression (and hence abdominal pattern) as a function of its concentration-dependent interaction with the NREs.

Animals↗
PubMed1992

Control of Drosophila body pattern by the hunchback morphogen gradient.

Most of the thoracic and abdominal segments of Drosophila are specified early in embryogenesis by the overlapping activities of the hunchback (hb), Krüppel, knirps, and giant gap genes. The orderly expression of these genes depends on two maternal determinants: bicoid, which activates hb transcription anteriorly, and nanos, which blocks translation of hb transcripts posteriorly. Here we provide evidence that the resulting gradient of hb protein dictates where the Krüppel, knirps, and giant genes are expressed by providing a series of concentration thresholds that regulate each gene independently. Thus, hb protein functions as a classical morphogen, triggering several distinct responses as a function of its graded distribution.

Animals↗
PubMed1994

Receptor serine/threonine kinases implicated in the control of Drosophila body pattern by decapentaplegic.

Members of the TGF beta superfamily of secreted signaling molecules regulate growth and cellular patterning during development and interact with specific type I and type II membrane receptors possessing a cytoplasmic serine/threonine kinase domain. We describe two members of the type I receptor family in Drosophila and demonstrate that they are encoded by the genes saxophone (sax) and thick veins (tkv). Further, we show that mutations that abolish sax or tkv activity cause phenotypes similar to partial or complete loss of activity, respectively, of the TGF beta homolog decapentaplegic (dpp). We propose that specification of distinct cell fates in response to different concentrations of dpp may be achieved combinatorially by the sax and tkv receptors.

Amino Acid Sequence↗
PubMed1994

Xenopus laevis embryos can establish their spatial bilateral symmetrical body pattern without gravity.

One assumes that gravity cooperates with the sperm in the establishment of bilateral symmetry in the embryo, particularly in species with yolky eggs. However, only experiments under genuine microgravity can prove this. May 2nd 1988 on the TEXUS-17 Sounding Rocket, eggs of Xenopus laevis became the first vertebrate eggs ever successfully fertilized in Space. Fertilization was done in fully automated hardware; the experiment was successfully repeated and extended in 1989. Here we report a "Space First" from the IML-1 Space Shuttle mission (January 1992): In similar hardware and under microgravity, artificially fertilized Xenopus eggs started embryonic development. Histological fixation was pre-programmed at the time gastrulation would occur on Earth and indeed, gastrulae were fixed. Thus after fertilization in near weightlessness Xenopus embryos do develop bilaterally symmetrically, very probably cued by the sperm alone.

Animals↗
PubMed2005

Changes in growth pattern, body composition and biochemical markers of growth after adenotonsillectomy in prepubertal children.

OBJECTIVE: Adenotonsillar hypertrophy (ATH) is associated with growth interruption during childhood. The aim of this study was to determine the changes in growth, body composition and biochemical markers associated with growth following adenotonsillectomy (A&T) in prepubertal children. STUDY DESIGN: Twenty-eight children aged 3-10 years (mean age 73.90 +/- 20.97 months) with ATH were followed up for 1 year after A&T. During the same period of time, 20 healthy children of similar ages (mean age 73.7 +/- 18.2 months) were followed up too. METHODS: Height, weight as well as insulin-like growth factor-1 (IGF-1) and insulin-like growth factor binding protein-3 (IGFBP-3) were measured during the preoperative period, 6 months and 1 year after surgery. RESULTS: Height and weight of the patient group significantly increased during the first year after A&T (p < 0.01). Increase in height standard deviation score (SDS) during the first postoperative year reflected a true acceleration of growth (p = 0.04). Height and weight of patients were not significantly below those of their healthy peers at the preoperative measurement. Height velocity of the patients (p = 0.118), which was similar to that of their healthy peers in the first 6 months postoperatively, was significantly higher at the end of the second 6-month period after the operation (p = 0.048). IGF-1 levels of the patient group, which were significantly lower than those of the controls preoperatively (p < 0.001), increased to similar levels 1 year after the operation. IGFBP-3 levels of the patient group increased significantly after postoperative sixth month (p = 0.002). CONCLUSION: Although children with ATH do not have significant growth retardation, their growth rate is slower. Increase in weight and IGF-1 levels followed by the increase in height leads to an acceleration in growth rate after A&T. These results have led to the conclusion that either the levels or effect of growth hormone (GH) increase following A&T.

Adenoidectomy↗