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PubMed2003

Strain-specific caspase-3-dependent programmed cell death in the early developing mouse forebrain.

Caspase-3-deficient 129/Sv mice show hyperplasia of the forebrain at embryonic day (E) 10.5, which suggests that caspase-3-dependent programmed cell death (PCD) plays an essential role in brain morphogenesis prior to neurogenesis. However, little is known about region-specific caspase-3-dependent PCD in the developing forebrain. We examined the PCD region in the early developmental brain at E9.5 by whole mount terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling (TUNEL). In addition to hindbrain, TUNEL-reactivity was detected in the ventral forebrain and in the caudal portion of the front nasal region, just behind the regions expressing fgf-8 and otx-2. It has been shown recently that brain hyperplasia induced by caspase-3-deficiency is mouse strain-dependent; such that brain abnormalities were observed in caspase-3-deficient 129/Sv mice but not in caspase-3-deficient C57BL/6 mice. We examined the caspase-3-dependent PCD in the ventral forebrain of 129/Sv and C57BL/6 mouse embryos (E8.5-9 and E9.5) by double staining of TUNEL and antiserum against the active form of caspase-3 (anti-m3D175). TUNEL/anti-m3D175 reactivity in the ventral forebrain was mouse strain-dependent, such that many TUNEL/anti-m3D175-positive cells were detected in the ventral forebrains of 129/Sv mice, but were not observed in C57BL/6 mice. Thus, it is likely that this region is the site of the strain-specific caspase-3-dependent PCD. A strain-dependent 'modulator' that regulates both caspase-3-dependent and -independent cell death pathways may control PCD in the ventral forebrain at E8.5-9.5.

Animals↗

PubMed1989

Gangliosides of sea urchin embryos. Their localization and participation in early development.

The influence of antibodies to gangliosides of sea urchin Strongylocentrotus intermedius eggs on early embryos of this species was studied. gamma-Globulins were isolated from rabbit anti-ganglioside serum by micropreparative electrophoresis. These gamma-globulins produced anomalies in the development of embryos permeabilized in Triton X-100. The anomalies were not observed when anti-ganglioside gamma-globulins were added to the incubation medium together with gangliosides or when the permeabilized embryos were incubated with gamma-globulins of normal rabbit serum. Pretreatment of S. intermedius embryos with serotonin, tryptamine or some other indole derivatives led to the disappearance of ganglioside determinants from the cell surface and sharply increased immunofluorescence within the cell. Such pretreatment of embryos increased the amount of cell-associated gangliosides more than threefold as compared to untreated embryos. Serotonin was shown to bind specifically to sea urchin gangliosides immobilized on octyl-Sepharose. These observations suggest that cell-surface gangliosides, after binding drugs, are internalized and that serotonin and its antagonists inhibit the transport of newly synthesized gangliosides to the cell-surface membrane.

Animals↗

PubMed1986

Testosterone induces hypothalamic aromatase during early development in quail.

The effects of testosterone on androgen metabolizing enzymes were examined in the developing hypothalamus of male and female quail using an in vitro radiometric assay which measures metabolite formation in individual brain samples. Testosterone (T) administered by subcutaneous silastic implants to gonadectomized 4-day-old chicks increased formation of estradiol-17 beta (E2) in both preoptic area + anterior hypothalamus (PA) and posterior hypothalamus + tuberal area (HT) to adult levels. The T-induced increase in E2 formation occurred to the same degree in both sexes. The increase was very small in control non-target areas, neostriatum intermediale + hyperstriatum ventrale (VN), of either sex. Testosterone had no effect on formation of 5 alpha-dihydrotestosterone (5 alpha-DHT), 5 beta-dihydrotestosterone (5 beta-DHT) and 5 beta-androstane 3 alpha, 17 beta-diol (5 beta, 3 alpha-diol) in PA. Kinetic analysis of the rate of E2 production by hypothalamic tissue from castrated chicks (CX-chicks) and castrates treated with T (CX + T-chicks) indicates that the increase in hypothalamic aromatase activity by T corresponds to induction of the enzyme: the Vmax (maximum velocity) was increased by T (CX-chicks, 21; CX + T-chicks, 91 fmol/mg FW/h), whereas the Km was unaffected (CX-chicks, 5.5; CX + T-chicks, 4.7 X 10(-8) M). Testosterone treatment, effective for inducing PA and HT aromatase activity, also activated crowing and caused cloacal gland development; neither of these effects were sexually dimorphic. Our results indicate that: (1) T induces aromatase specifically in the hypothalamus during early post-hatching development, other pathways of T metabolism are not affected; and (2) the inducible aromatase is not sexually dimorphic in the developing brain. Since there are sex differences in adult brain aromatase, we conclude that capacity for induction of the hypothalamic aromatase becomes sexually differentiated after the post-hatching period.

Animals↗

PubMed1985

Mapping the distribution of differentiation potential for intestine, muscle, and hypodermis during early development in Caenorhabditis elegans.

We have analyzed the differentiation potential of cells in early embryos of Caenorhabditis elegans by assessing the production of markers for intestinal, muscle, and hypodermal cell differentiation in cleavage-arrested blastomeres. Our results show that differentiation potential does not always segregate during cleavage in a linear fashion, i.e., a blastomere can express a differentiation potential that is absent in its parent blastomere and vice versa. Furthermore, the expression of a particular differentiation program by certain cleavage-arrested blastomeres is an exclusive event in that each cell will express only one program of differentiation, even though it may have the potential to express several.

Animals↗

PubMed1984

Transcription and polyadenylation processes during early development of quail embryo.

Transcription of tRNA and mRNA occurs in quail as early as during cleavage while rRNA transcription becomes measurable during blastulation. The polyadenylated fraction content is newly synthesized RNA amounting to 6% during cleavage and blastulation decreases to 3% during gastrulation. Up to 3/4 adenylic residues incorporated into RNA during cleavage are accumulated in the polyadenylated molecules mainly in the form of RNAse-resistant tracts.

Animals↗

PubMedDate not supplied

Phosphorylation of brain and liver ribosomal proteins during early development of chick embryo.

32P-ortophosphate was introduced intraamnionally into 5, 9, 12, 15 and 19 day-old chick embryos. After 4 hours the specific activity of brain and liver ribosomal proteins and their fractions were determined. It was found that the specific activities of those in both tissues were highest at the early stages of development, and they declined rapidly to reach the lowest value at day 19. The observed differences between brain and liver ribosomal proteins are consistent with an unequal rhythm of ontogenesis.

Animals↗

PubMed2005

Superantigen hypothesis for the early development of chronic hyperplastic sinusitis with massive nasal polyposis.

PURPOSE OF REVIEW: The pathogenesis, pathophysiology, and immunobiology of chronic hyperplastic sinusitis with massive nasal polyposis are starting to become unraveled. Allergy, viral infection, bacterial infection, fungal infection, and environmental pollution have all been suggested as possible initial triggers that may upregulate inflammation of the lateral wall of the nose to develop nasal polyposis. The purpose of this review is to present data from our laboratory that suggest that one of the possible early events in the development of inflammation of the lateral wall of the nose in chronic hyperplastic sinusitis with massive nasal polyposis is the production of exotoxins from Staphylococcus aureus. The exotoxins may act as superantigens and cause activation and clonal expansion of lymphocytes with specific Vbeta regions, resulting in massive cytokine production. RECENT FINDINGS: Recent published studies suggest that S. aureus is the most common organism isolated from the mucus adjacent to massive nasal polyposis. Staphylococci produce exotoxins. These exotoxins, sometimes known as enterotoxins, include SEA, SEB, and TSST-1. These exotoxins are capable of acting as superantigens and therefore, reacting with T lymphocytes with specific Vbetas in the lateral wall of the nose. Thereafter, it is possible that these lymphocytes are stimulated to produce both TH1 and TH2 cytokines, which have also been demonstrated in the nasal polyp. The consequence of these findings may be the upregulation and increased survival of eosinophils in the nasal polyp. SUMMARY: Staphylococcus aureus is present in the mucin adjacent to nasal polyps in about 60 to 70% of cases of massive nasal polyposis. These organism, as studied up to the present, always produce exotoxins, which may act as superantigens, causing activation and clonal expansion of lymphocytes with specific Vbeta region in the lateral wall of the nose. The present review suggests that activation of these lymphocytes produce both TH1 and TH2 cytokines. The potential damage to the nasal mucosa from eosinophils is briefly discussed. Theoretically, topical antibiotics to suppress the colonization of S. aureus may be a logical approach to downregulate the production of superantigen in the lateral wall of the nose after appropriate endoscopic sinus surgery.

Bacterial Toxins↗

PubMed1988

A unique membrane protein is expressed on early developing limbic system axons and cortical targets.

The limbic system-associated membrane protein (LAMP) is a 64 kDa protein that, in the adult brain, is present in cortical and subcortical regions comprising the limbic system (Levitt, 1984). The developmental expression of LAMP was studied in fetal rat brains to determine the specific patterns of distribution and the cellular elements that exhibit LAMP immunoreactivity. Light microscopic immunocytochemical analysis revealed that LAMP is expressed on neurons and their growing axons early in fetal development, at a time coincident with pathway formation and differentiation of limbic system nuclei. In the forebrain, where limbic system structures are heavily concentrated, immunoreactivity appears on subpopulations of axons in a temporal sequence that correlates with the time of formation of pathways carrying limbic system axons. Thus, staining is evident first at embryonic day (E) 15 on fibers within the internal capsule coursing from the diencephalon to cortex. LAMP immunoreactivity appears over the next 3 d in the anterior commissure, fornix, and corpus callosum. Ultrastructural immunocytochemical analysis reveals dense surface staining of fascicles of developing axons and growth cones. The axonal staining is transient, disappearing during the second postnatal week of development. In cerebral cortex, cells in presumptive limbic cortical regions such as lateral perirhinal sulcal cortex and prefrontal cortex are LAMP immunoreactive from the inception of the cortical plate. These cortical regions are clearly delineated from surrounding unstained nonlimbic areas as early as E15. Thus, LAMP expression in the cortex may represent one of the earliest markers of specific cytoarchitectonic areas.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1999

Early development of the müllerian duct in avian embryos with reference to the human. An ultrastructural and immunohistochemical study.

In vertebrates, the female reproductive system arises from the Müllerian (paramesonephric) duct which develops in both sexes under the influence of the Wolffian (mesonephric) duct. For a better understanding of the interactions between the Müllerian duct and its adjacent tissues, we present a systematic scanning and transmission electron microscopic investigation of early stages of avian Müllerian duct development. This starts within the cranial part of the Müllerian ridge from a placode-like thickening and deepening of the coelomic epithelium containing nephrostomes as remnants of the last pronephric and first mesonephric tubules. Groups of cells detach from this placode and rapidly expand caudally as a solid cord. This becomes canalized, but the tip region remains mesenchymal and is found enclosed within the basal lamina of the Wolffian duct. Immunostaining reveals that the Müllerian duct migrates within a matrix rich in laminin and entactin. When the canalized duct has opened into the coelomic cavity, one or more secondary ducts are found immediately caudal of the main funnel, for a short period only, possibly to supply material to the expanding duct. BrdU-anti-BrdU reaction reveals a high proliferation of the duct epithelium. The thickened epithelium of the Müllerian ridge dissolves to form the mesenchymal layers of the duct. Immunostaining with vimentin argues against a cellular contribution of Wolffian duct cells to the Müllerian duct. Comparing the data from avian embryos with those of human indicates that the modalities of early Müllerian duct development are similar in both species.

Animals↗

PubMedDate not supplied

Changes in plasma membrane protein composition during early development of the frog Rana ridibunda.

Plasma membranes of fully-grown oocytes and early developmental stage embryos of Rana ridibunda were isolated by differential and density gradient centrifugation; they were purified 18-fold as indicated by 5'-nucleotidase. The plasma membrane protein pattern of five different developmental stages was studied by two-dimensional polyacrylamide gel electrophoresis. More than 60 protein species could be detected by silver staining. Most of them are largely conserved during development. The rest either show precise stage specificity or exhibit stronger staining intensity at particular stages. The number of proteins specific for each stage is small, neurula being exempted. The changes observed in the plasma membrane profile during development are mostly prominent in a group of proteins with similar molecular weights (40-45 kDa) but with different pI values. The differences observed in the plasma membrane patterns are discussed in relation to the significance of each stage during development.

Animals↗

PubMed1995

Critical periods of early development created by the coordinate modulation of ion channel properties.

The development of ion channel properties in excitable cells begins in the very early embryo and continues throughout differentiation. The pattern of ion channel development in a given cell type is not a simple linear progression to the mature state, but rather is a complex sequence of modulatory events that create windows of time during which excitability is qualitatively different from that in the mature cell. These windows are likely candidates for critical periods when electrical activity influences later development.

Animals↗

PubMed2004

Immunolocalization of Na+,K+-ATPase in the branchial cavity during the early development of the crayfish Astacus leptodactylus (Crustacea, Decapoda).

The ontogeny of osmoregulation was examined in the branchial cavity of embryonic and early post-embryonic stages of the crayfish Astacus leptodactylus maintained in freshwater, at the sub-cellular level through the detection of the sodium-potassium adenosine triphosphatase (Na(+),K(+)-ATPase). The embryonic rate of development was calculated according to the eye index (EI) which was 430-450 microm at hatching. The distribution of the enzyme was identified by immunofluorescence microscopy using a monoclonal antibody IgGalpha5 raised against the avian alpha-subunit of the Na(+),K(+)-ATPase. Immunoreactivity staining, indicating the presence of Na(+), K(+)-ATPase appeared in the gills of late embryos (EI>/=400 microm), i.e. a few days before hatching time, and steadily increased throughout the late embryonic and early post-embryonic development. The appearance of the enzyme correlates with the ability to osmoregulate which also occurs late in the embryonic development at EI 410-420 microm and with tissue differentiation within the gill filaments. These observations indicate that the physiological shift from osmoconforming embryos to hyper-regulating late embryos and post-hatching stages in freshwater must originate partly from the differentiation in the gill epithelia of ionocytes which are the site of ion pumping, as suggested by the location of Na(+),K(+)-ATPase. Only the gills were immunostained and a lack of specific staining was noted in the lamina and the branchiostegites. Therefore, osmoregulation through Na(+)active uptake is likely achieved in embryos at the gill level; all the newly formed gills in embryos function in ion regulation; other parts of the branchial chamber such as the branchiostegites and lamina do not appear to be involved in osmoregulation.

Animals↗

PubMed2004

Global changes in genomic methylation levels during early development of the zebrafish embryo.

We have examined the methylation status of the zebrafish genome during early embryogenesis and we find evidence that methylation fluxes do occur in that organism. The parental genetic contributions to the zygote are, initially, differently methylated with the genome of the sperm being hypermethylated relative to the genome of the oocyte. Post-fertilization there is an immediate decrease in methylation of the embryonic genome but the methylation begins to increase rapidly and is re-established by the gastrulation stage. These results are consistent with the results of Santos et al. (Dev Biol 241:172-182, 2002), who examined the methylation of early mouse embryos, and this conservation argues that demethylation/re-methylation is an important part of vertebrate development.

Animals↗

PubMed1977

An experimental investigation into the early development of the chick elbow joint.

The theory that differential growth of opposed chondrogenic centres is important in early joint formation has been tested experimentally by removing structures in relation to the chick elbow joint. The humerus and its cap of differentiating joint cells were found to develop independently of structures distal to them. Removal of the presumptive joint region at early stages resulted in fusion of the humerus with the radius and ulna. Results are discussed in terms of concepts concerning pattern formation of cell types in the early wing-bud.

Animals↗

PubMed1996

Pathological study of Japanese quail embryo with acid alpha-glucosidase deficiency during early development.

A pathological study was performed on the tissues of 11 Japanese quail embryos with type II glycogen storage disease (GSD II) between incubation day (ID) 3 and ID 15. Accumulation of glycogen in vacuoles derived from lysosomes was first seen in cardiac muscle at ID 3, in liver at ID 5, in wing muscle at ID 7, and in pectoral muscle at ID 10. The number and size of the glycogen vacuoles gradually increased during development, especially in cardiac muscle. Cytoplasmic glycogen particles, showing the same density as membrane-enclosed glycogen particles, were first seen as masses in cardiac muscle at ID 3, in liver at ID 5, in pectoral muscle at ID 10, and in wing muscle at ID 15. The area of cytoplasm occupied by the glycogen particles increased during development. Myofibrillar degeneration was not seen, although myofibrils appeared in disarray in the early stages, as in normal embryos. This is the first study of the development of embryonic tissues of Japanese quails with GSD II. GSD II in the Japanese quail appears to be clinically analogous to the human late (juvenile)-onset disease, although the disorder starts at very early stages in quail embryos. Therefore, Japanese quails with GSD II can provide a model for elucidating the pathogenetic process of human GSD II.

Animals↗

PubMed1969

Maternal and embryonic contributions to the functional messenger RNA of early development.

Some of the DNA-like RNA synthesized during oögenesis remains available up to early blastula (stage 7). This RNA then begins to disappear from the embryo, so that by early gastrulation half of its sequences have been lost. Total maternal RNA of embryos represents more sequences than can be recovered at early stages from polyribosomes. Some of it must therefore reside in cytoplasmic fractions that do not cosediment with polyribosomes. Most of the maternal DNA-like RNA is eventually translated before it is lost. Messenger RNA transcribed on the embryonic genomes appears very early on polyribosomes and is translated there along with maternal RNA.

Animals↗

PubMed1999

Early development of descending supraspinal pathways: a tracing study in fixed and isolated rat embryos.

Early brainstem-spinal cord projections were studied in the rat using the carbocyanine dye DiI in fixed embryos and biotinylated dextran amine (BDA) in an isolated embryonic brain-spinal cord preparation. A system of staging embryos was used that allows direct comparison with data in other mammals. With both techniques it was shown that in embryos of at least 12 days of age (E12), i.e., at the time of closure of the posterior neuropore, already a variety of brainstem centers innervate the spinal cord. In the interstitial nucleus of the fasciculus longitudinalis medialis and various parts of the reticular formation - mesencephalic, pontine as well as medullary - DiI or BDA labelled neurons were observed. Mainly large immature, bipolar neurons were labeled. In later stages (E13, E14) the number of labeled neurons increased and more mature, multipolar cells were found. Labeled neurons were also observed in the vestibular nuclear complex and in the medullary raphe. Just below the cerebellum a conspicuous small group of neurons was found labeled in a position reminiscent of the locus coeruleus. Comparison with available data on the time of neuron origin of brainstem neurons suggests that interstitiospinal and reticulospinal neurons start projecting spinalwards shortly after they are generated. The earliest brainstem projections to the spinal cord all pass via the fasciculus longitudinalis medialis.

Animals↗

PubMed1990

Aromatase, 5-alpha-reductase, and androgen receptor levels in the fetal monkey brain during early development.

Aromatase, 5 alpha-reductase and cytosolic androgen receptor levels were measured in the medial basal hypothalamus (MHB), amygdala (AMG), cerebellum and cerebral cortex of male and female fetal rhesus monkeys on day 70 of gestation. Higher aromatase activities were noted in the MBH and AMG of male than female fetuses. In contrast, no sex differences were found for 5 alpha-reductase and androgen receptor levels. These data suggest that at this early stage of development, differentiation of the MBH and AMG of the male fetus may be more susceptible to androgen modification, by way of aromatization to estrogens, than corresponding areas in the female fetus. Moreover, based upon a comparison of the current data to that published previously for later stages of development, it is suggested that the sex differences in aromatase activity are not the result of androgen stimulation.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗