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PubMed1995

Image analytical observation on the growth and development of Clonorchis sinensis in rats.

For the two-dimensional observation on the growth and development of Clonorchis sinensis, an image analysis system (IBAS 2000, Kontron, Germany) was used in this study. On 3, 6, 9, 12, 15, 21, 30 and 90 days of infection, 474 worms were collected from rats infected with 50 metacercariae each. The overall recovery rate was 31.6%. The worms grew rapidly in their length and width up to 30 days of infection and then, did slowly to 90 days of infection. However, the growth pattern of body area was not similar to that of body length and width, because the body area increased continuously even after 30 days of infection. With the image analysis system, the sizes of irregular-shaped genital organs were measured easily, which showed sigmoidal growth patterns. The growth rate of genital organs increased rapidly until 21 days of infection when the uterus was filled with numerous eggs, and then gradually slowed down to 90 days. There was no difference in growth pattern between the anterior and posterior testis. The seminal receptacle, however, showed an abrupt increase in size between 15 to 21 days of infection when it was filled with condensed semen. Therefore, the growth pattern of seminal receptacle might be used as another criteria to estimate the extent of sexual maturation of C. sinensis. From this study, it is suggested that image analysis system is very useful to reveal the growth and development pattern of C. sinensis, especially of their internal organs.

Animals↗
PubMed2003

Developmental changes in expression patterns of two dopamine receptor genes in mushroom bodies of the honeybee, Apis mellifera.

The expression patterns of two dopamine receptor genes, Amdop1 and Amdop2, in the developing mushroom bodies of the honeybee brain were determined by using in situ hybridisation. Both genes were expressed throughout pupal development, but their patterns of expression in the three major divisions of mushroom body intrinsic neurons (outer compact cells, noncompact cells, and inner compact cells) were quite distinct. Amdop1 expression could be detected in all three mushroom body cell groups throughout development. Staining for Amdop1 mRNA was particularly intense in newly born Kenyon cells, suggesting that levels of Amdop1 expression are higher in newborn cells than in more mature mushroom body neurons. This was not the case for Amdop2. Amdop2 expression in the mushroom bodies was restricted to inner and outer compact cells during most of pupal development, appearing in noncompact cells only late in metamorphosis or at adult eclosion. In contrast to the case with Amdop1, staining for Amdop2 mRNA was observed in glial cells. Expression of Amdop2 in glial cells was detected only at early stages of glial cell development, when the cells are reported to be actively dividing. This study not only implicates dopamine in the development of honeybee mushroom bodies but also suggests different roles for the two dopamine receptors investigated.

Animals↗
PubMed1975

On the regulation of the renal response blood volume expansion by vascular parameters in the rat.

The dynamic patterns of body fluid volume distribution, of cardiovascular variables and of renal water, sodium and potassium excretion were studied in the anaesthetized rat following acute, iso-oncotic blood volume expansion. The increased renal excretion following expansion was soon reversed and its pattern to termination was not correlated with changes in pulse and mean arterial pressure, in plasma electrolyte concentration or in haematocrit. At the end of the renal response the change in extracellular fluid volume was not usually corrected, the blood volume was always well above its control value and the interstitial fluid was below its control value. In all cases the temporal pattern and the termination of the renal response corresponded closely with the temporal pattern and the return to the control value of the central venous mean and pulse pressure. The findings of thse experiments are not consistent with the view that any of the measured body fluid volumes directly and always determine renal excretion. It is proposed that in response to an acute blood volume expansion an animal may initially regulate neither its blood volume nor its extracellular fluid volume but rather a factor which is reflected in or related to the central venous pressure.

Animals↗
PubMedDate not supplied

Predicting success in antihypertensive drug therapy: the importance of nondrug variables.

The hypothesis of this study was that specific lifestyle patterns would be predictive of, or increase the risk for, uncontrolled hypertension in drug-treated hypertensive subjects. By means of a previously validated questionnaire, alcohol consumption, smoking, exercise, calcium intake, sodium intake, caffeine intake, body weight pattern and perceived stress level were evaluated in 364 subjects who attended a hypertension clinic in a large urban teaching hospital. The subjects were divided into controlled and uncontrolled categories on the basis of a clinic blood pressure reading. The number of prescribed drugs was not different between the two groups. Stratified analysis identified a high perceived stress level, a high calcium intake, and a lower body mass index as predictive of uncontrolled hypertension. Other variables showed no significant correlation. The conclusion of the study is that traditional risk factors for hypertension may assume less importance in drug-treated hypertensive patients than in untreated hypertensive patients.

Adolescent↗
PubMed1997

Ontogenetic variation in small-bodied New World primates: implications for patterns of reproduction and infant care.

This paper explores relations of ontogeny, life history strategies and patterns of infant care in 11 species of small-bodied New World monkeys. Analysis of these data suggests that differences in the social systems of Aotus, Callicebus, Saimiri, Callimico, Saguinus, Leontopithecus, Cebuella and Callithrix are closely tied to both the costs of reproduction and to the ontogenetic requirements of maturing young. In Saimiri, both rapid prenatal body weight and perinatal brain growth result in relatively high metabolic costs to breeding females. These costs, coupled with minimal nonmaternal assistance in caregiving, appear to favor a reproductive strategy that limits offspring production to a single birth at 2-year intervals. In contrast, tamarins and marmosets are capable of producing twins twice in the same year. Prenatal investment in each offspring is relatively low, and the potentially high postnatal costs of nursing 2 infants are minimized by the evolution of a social system involving extensive extramaternal care-giving. Cooperative infant care in callitrichins (tamarins and marmosets) serves to distribute the metabolic costs of infant ontogeny among several group members. Callimico is also characterized by a high reproductive output, with females capable of producing a single infant twice during the year. Infants continue to grow rapidly after weaning. Patterns of infant development in Callimico are similar to those found in tamarins and marmosets and support a close phylogenetic relationship among these taxa. Aotus and Callicebus are characterized by an alternative strategy. In these taxa, a monogamous mating system is associated with paternal certainty, male parental care, and provisioning of the young. The transfer of male energetic resources to a single offspring allows night and titi monkeys to maintain a comparatively short interbirth interval (1 year). Ecological and social factors, such as predation and feeding competition, do not appear to adequately explain much of the observed variation in infant development and preadult growth rates in these platyrrhines. Instead, reproductive strategies are strongly linked to ontogenetic patterns and life histories.

Aging↗
PubMed2006

The deuterostome ancestor.

Hemichordates, the phylum of bilateral animals closest to chordates, can illuminate the evolutionary origins of various chordate traits to determine whether these were already present in a shared ancestor (the deuterostome ancestor) or were evolved within the chordate line. We find that an anteroposterior map of gene expression domains, representing 42 genes of neural patterning, is closely similar in hemichordates and chordates, though it is restricted to the neural ectoderm in chordates whereas in hemichordates, which have a diffuse nervous system, it encircles the whole body. This map allows an accurate alignment of the anterioposterior axes of members of the two groups. We propose that this map dates back at least to the deuterostome ancestor. The map of dorsoventral expression domains, organized along a Bmp-Chordin developmental axis, is also similar in the two groups in terms of many gene expression domains and for the placement of the gill slits, heart, and post-anal tail. The two groups, however, differ in two major respects along this axis. The nervous system and epidermis are not segregated into distinct territories in hemichordates, as they are in chordates, and furthermore, the mouth is on the Chordin side in hemichordates but the Bmp side in chordates. The dorsoventral dimension has undergone extensive modification in the chordate line, including centralization of the nervous system, segregation of epidermis, derivation of the notochord, perhaps from the gut midline, and relocation of the mouth. Based on the shared domain maps, speculations can be made for the remodeling of the body axis in the chordate line.

Animals↗
PubMed2001

Constitutive expression and localization of COX-1 and COX-2 in rabbit iris and ciliary body.

Prostaglandins are involved in the regulation of intraocular pressure and the blood-aqueous barrier of the eye, and are used for the treatment of glaucoma. The decrease of the constitutively expressed PG-synthesizing enzyme cyclooxygenase-2 (COX-2) has been demonstrated in the ciliary non-pigmented epithelial layer of patients with primary open angle glaucoma. Little is known about the distribution of COX-1 and COX-2 in animals. We investigated this in the iris and ciliary body of the normal rabbit eye. The presence of COX-1 and COX-2 in freshly excised iris and ciliary body tissue from adult New Zealand White albino rabbits was demonstrated by real-time RT-PCR, and Western blot analysis. The localization of both isoforms and of the neuron-specific protein gene product 9.5 was determined by indirect immunofluorescence. Both enzymes are expressed in the iris and the ciliary body. Immunofluorescence studies including double staining techniques localized COX-1 and COX-2 to about 50% of cells in the stromal tissue of iris and ciliary body, mainly on the corneal side. They were co-localized in about 75% of these cells. Whereas all stained cells were positive for COX-1, COX-2 showed a gradient-like distribution in the stroma, with some restriction of expression near the epithelial layers, which we clearly showed to be completely negative for both COX-1 and COX-2. Also, neuronal elements did not show COX-1 or COX-2 immunoreactivity. These results establish the presence of COX-1 and COX-2 on the RNA and protein levels in normal, unstimulated rabbit iris and ciliary body. The pattern of distribution suggests a role for both enzymes in maintaining the physiology of the eye. In contrast to our results in man, non-pigmented epithelial cells of the ciliary body did not express immunoreactivity. This could account for differences in the regulation of intraocular pressure and/or blood-aqueous barrier between human and rabbit eyes.

Animals↗
PubMed1985

Developmental control of Drosophila yolk protein 1 gene by cis-acting DNA elements.

In this paper we have demonstrated that at least two tissue-specific cis-acting DNA elements are necessary for the normal developmental pattern of Drosophila yp1 gene expression. One of these elements is necessary for expression in the adult female follicle cells and the other is necessary for expression in adult female fat bodies. We have localized the fat body expression element to a 125-bp fragment that lies between nucleotides -196 and -321 of the yp1 gene. This small fragment has at least one of the characteristics of enhancer sequences because it can direct a heterologous Drosophila promoter to be transcribed with the yp1 fat body expression pattern.

Animals↗
PubMed1999

Genetics of epithelial polarity and pattern in the Drosophila retina.

This review is focused on recent advances in our understanding of the development of coordinated cell polarity, through experiments on the Drosophila compound eye. Each eye facet (or "ommatidium") contains a set of eight photoreceptor cells, placed so that their rhabdomeres form an asymmetric trapezoid. The array of ommatidia is organized so that these trapezoids are aligned in two mirror-image fields, dorsal and ventral to the eye midline (or "equator"). The development of this pattern depends on two systems of positional information that inform the cluster of cells that will form an ommatidium of anterior/posterior (a/p) and dorsal/ventral (d/v) direction. The former (a/p) is encoded by a progressive wave of development (the morphogenetic furrow). The latter (d/v) involves molecules known to act in tissue polarity in other organs and organisms. Our understanding of the function of these molecules rests not only on their mutant phenotypes, biochemistry, and expression patterns, but also on the spatial effects when mutant patches of cells are made (genetic mosaics).

Animals↗
PubMed2000

Pallial and subpallial derivatives in the embryonic chick and mouse telencephalon, traced by the expression of the genes Dlx-2, Emx-1, Nkx-2.1, Pax-6, and Tbr-1.

Pallial and subpallial morphological subdivisions of the developing chicken telencephalon were examined by means of gene markers, compared with their expression pattern in the mouse. Nested expression domains of the genes Dlx-2 and Nkx-2.1, plus Pax-6-expressing migrated cells, are characteristic for the mouse subpallium. The genes Pax-6, Tbr-1, and Emx-1 are expressed in the pallium. The pallio-subpallial boundary lies at the interface between the Tbr-1 and Dlx-2 expression domains. Differences in the expression topography of Tbr-1 and Emx-1 suggest the existence of a novel "ventral pallium" subdivision, which is an Emx-1-negative pallial territory intercalated between the striatum and the lateral pallium. Its derivatives in the mouse belong to the claustroamygdaloid complex. Chicken genes homologous to these mouse genes are expressed in topologically comparable patterns during development. The avian subpallium, called "paleostriatum," shows nested Dlx-2 and Nkx-2.1 domains and migrated Pax-6-positive neurons; the avian pallium expresses Pax-6, Tbr-1, and Emx-1 and also contains a distinct Emx-1-negative ventral pallium, formed by the massive domain confusingly called "neostriatum." These expression patterns extend into the septum and the archistriatum, as they do into the mouse septum and amygdala, suggesting that the concepts of pallium and subpallium can be extended to these areas. The similarity of such molecular profiles in the mouse and chicken pallium and subpallium points to common sets of causal determinants. These may underlie similar histogenetic specification processes and field homologies, including some comparable connectivity patterns.

Age Factors↗
PubMed2002

Revisions to the Xenopus gastrula fate map: implications for mesoderm induction and patterning.

A revised fate map of the gastrula Xenopus embryo predicts the existence of patterning mechanisms that operate within the animal/vegetal axis of the mesoderm-forming marginal zone. We review here molecular and embryologic data that demonstrate that such mechanisms are present and that they operate independently of the Spemann organizer. Evidence suggests that polarized fibroblast growth factor activity in the animal/vegetal axis patterns this axis. We present a model of mesoderm induction and patterning that integrates the new data on Spemann organizer-independent animal/vegetal patterning with data on other inductive pathways known to act on the gastrula marginal zone.

Animals↗
PubMed2005

Identification of neural genes using Xenopus DNA microarrays.

To isolate novel genes regulating neural induction, we used a DNA microarray approach. As neural induction is thought to occur by means of the inhibition of bone morphogenetic protein (BMP) signaling, BMP signaling was inhibited in ectodermal cells by overexpression of a dominant-negative receptor. RNAs were isolated from control animal cap explants and from dominant-negative BMP receptor expressing animal caps and subjected to a microarray experiment using newly generated high-density Xenopus DNA microarray chips representing over 17,000 unigenes. We have identified 77 genes that are induced in animal caps after inhibition of BMP signaling, and all of these genes were subjected to whole-mount in situ hybridization analysis. Thirty-two genes showed specific expression in neural tissues. Of the 32, 14 genes have never been linked to neural induction. Two genes that are highly induced by BMP inhibition are inhibitors of Wnt signaling, suggesting that a key step in neural induction is to produce Wnt antagonists to promote anterior neural plate development. Our current analysis also proves that a microarray approach is useful in identifying novel candidate factors involved in neural induction and patterning.

Animals↗
PubMed2005

Studies on epidermal growth factor receptor signaling in vertebrate limb patterning.

The epidermal growth factor receptor (EGFR) regulates multiple patterning events in Drosophila limb development, but its role in vertebrate limb morphogenesis has received little attention. The EGFR and several of its ligands are expressed in developing vertebrate limbs in manners consistent with potential patterning roles. To gain insight into functions of EGFR signaling in vertebrate limb development, we expressed a constitutively active EGFR in developing chick limbs in ovo. Expression of activated EGFR causes pre- and postaxial polydactyly, including mirror-image-type digit duplication, likely due to induction of ectopic expression and/or modulation of genes involved in anterior-posterior (AP) patterning such as Sonic hedgehog (Shh), dHand, Patched (Ptc), Gli3, Hoxd13, Hoxd11, bone morphogenetic protein 2 (Bmp2), Gremlin, and FGF4. Activation of EGFR signaling dorsalizes the limb and alters expression of the dorsal-ventral (DV) patterning genes Wnt7a, Lmx, and En1. Ectopic and/or extended FGF8 expressing apical ectodermal ridges (AERs) are also seen. Interdigital regression is inhibited and the digits fail to separate, leading to syndactyly, likely due to antiapoptotic and pro-proliferative effects of activated EGFR signaling on limb mesoderm, and/or attenuation of interdigital Bmp4 expression. These findings suggest potential roles for EGFR signaling in AP and DV patterning, AER formation, and cell survival during limb morphogenesis.

Animals↗
PubMed2006

Definitive endoderm of the mouse embryo: formation, cell fates, and morphogenetic function.

The endoderm is one of the primary germ layers but, in comparison to ectoderm and mesoderm, has received less attention. The definitive endoderm forms during gastrulation and replaces the extraembryonic visceral endoderm. It participates in the complex morphogenesis of the gut tube and contributes to the associated visceral organs. This review highlights the role of the definitive endoderm as a source of patterning cues for the morphogenesis of other germ-layer tissues, such as the anterior neurectoderm and the pharyngeal region, and also emphasizes the intricate patterning that the endoderm itself undergoes enabling the acquisition of regionalized cell fates.

Animals↗
PubMed1996

Pattern formation by lateral inhibition with feedback: a mathematical model of delta-notch intercellular signalling.

In many developing tissues, adjacent cells diverge in character so as to create a fine-grained pattern of cells in contrasting states of differentiation. It has been proposed that such patterns can be generated through lateral inhibition--a type of cell-cell interaction whereby a cell that adopts a particular fate inhibits its immediate neighbors from doing likewise. Lateral inhibition is well documented in flies, worms and vertebrates. In all of these organisms, the transmembrane proteins Notch and Delta (or their homologues) have been identified as mediators of the interaction--Notch as receptor, Delta as its ligand on adjacent cells. However, it is not clear under precisely what conditions the Delta-Notch mechanism of lateral inhibition can generate the observed types of pattern, or indeed whether this mechanism is capable of generating such patterns by itself. Here we construct and analyse a simple and general mathematical model of such contact-mediated lateral inhibition. In accordance with experimental data, the model postulates that receipt of inhibition (i.e. activation of Notch) diminished the ability to deliver inhibition (i.e. to produce active Delta). This gives rise to a feedback loop that can amplify differences between adjacent cells. We investigate the pattern-forming potential and temporal behaviour of this model both analytically and through numerical simulation. Inhomogeneities are self-amplifying and develop without need of any other machinery, provided the feedback is sufficiently strong. For a wide range of initial and boundary conditions, the model generates fine-grained patterns similar to those observed in living systems.

Animals↗
PubMed1997

Eph-related receptors and their ligands: mediators of contact dependent cell interactions.

Recent studies of the large families of Eph-related receptor tyrosine kinases and their ligands suggest that they have key roles in embryonic development. These receptors mediate cell contact dependent signalling by binding to membrane-bound ligands, and certain ligands may themselves transduce signals. Functional studies indicate that in a number of tissues the receptors and ligands are expressed in complementary domains and mediate repulsive interactions that restrict cell and axon migration. In addition, they can also stimulate cell migration. Eph-related receptors and their ligands are therefore mediators of cell interactions required for tissue patterning and neuronal pathfinding during development. The potential clinical implications of these findings are discussed.

Animals↗
PubMed2004

Emerging asymmetry and embryonic patterning in early mouse development.

Recent studies have revealed asymmetries in the mouse zygote and preimplantation embryo, well before the establishment of anterior-posterior polarity after implantation. Whether these asymmetries are causally related to embryonic patterning or are coincidental outcomes of the topology of normal development remains uncertain.

Animals↗
PubMed2006

Quantitative models of developmental pattern formation.

Pattern formation in developing organisms can be regulated at a variety of levels, from gene sequence to anatomy. At this level of complexity, mechanistic models of development become essential for integrating data, guiding future experiments, and predicting the effects of genetic and physical perturbations. However, the formulation and analysis of quantitative models of development are limited by high levels of uncertainty in experimental measurements, a large number of both known and unknown system components, and the multiscale nature of development. At the same time, an expanding arsenal of experimental tools can constrain models and directly test their predictions, making the modeling efforts not only necessary, but feasible. Using a number of problems in fruit fly development, we discuss how models can be used to test the feasibility of proposed patterning mechanisms and characterize their systems-level properties.

Animals↗