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At least 19 recordsLinked to original sources
PubMed1992

Early development in healthy children of serum opsonins against nonpathogenic Neisseria meningitidis.

In an earlier study, with the use of chemiluminescence (CL) and phagocytic killing, we could show that in the presence of serum from healthy adults polymorphonuclear leukocytes (PMNL) efficiently handle nonpathogenic Neisseria meningitidis strains, in sharp contrast to those associated with clinical disease. The major part of this difference was dependent on serum factors. In the present study 84 serum samples from children 1-3, 4-6, 7-9, and 10-14 years old were studied by the CL technique according to their ability to opsonize meningococci. There was a highly significant difference (p less than 0.001) in all four age groups when the CL indexes obtained with the pathogenic meningococci of the serogroups A, B and C were compared with those of the nonpathogenic menigococci: serogroup 29E and nongroupable meningococci. These findings imply that the ability to opsonize so-called nonpathogenic meningococci is developed early in life and may explain why they are only occasionally able to cause disease.

Adolescent↗
PubMed1978

On the development of the cerebellum of the trout, Salmo gairdneri. II. Early development.

The early histogenesis of the cerebellum of Salmo gairdneri RICHARDSON, 1836 has been studied in fish ranging in length from about 5 to 14 mm, both with light microscopical and electron microscopical techniques. Structurally, the matrix cells correspond to those of other vertebrates. Mitoses occur predominantly at the ventricular surface, but peripheral mitoses are found as well, particularly in the period of highest mitotic activity. Mantle cell somata can be distinguished from the elongated matrix cells on the basis of their rounded shape. The neurogenetic and gliogenetic periods overlap considerably. Presumably the first mantle cells are all neuroblasts: as soon as the mantle layer starts to form, axonal profiles are found. In a slightly later stage glial differentiation is manifest in the radial processes contacting the meningeal surface. In young stages a distinction between neuroblasts and glioblasts can only be made on the basis of the structure of their processes. Processes of glioblasts can be distinguished from axons and dendrites by their paucity of microtubules. Dendrites, appearing in late-embryonic stages, contain the same organelles as axons, but in larger amounts. The first differentiation of mantle cell somata is an increase of rough endoplasmic reticulum, and that to a lesser degree in glioblasts than in neuroblasts. Neuronal nuclei are rounded and more electronlucent than those of mantle cells. Apart from zonulae adhaerentes between the internal processes of matrix cells, puncta adhaerentia occur frequently in the cerebellar anlage. However, they rarely occur on young neuron;. The possible significance of these junctions is discussed. The present study indicates that growth cones and filopodia are characteristic of most and probably of all types of cells in the early developing cerebellum. Growth cones contain much vesicular and tubular endoplasmic reticulum and in filopodia a fine filamentous network is present. In the somata of mantle cells growth areas were found, i.e. areas under the cell membrane with a similar content as growth cones. It is suggested that these areas anticipate the outgrowth of a new process.

Animals↗
PubMed1992

Direct-developing sea urchins and the evolutionary reorganization of early development.

The evolution of development can be made accessible to study by exploiting closely related species that exhibit distinct ontogenies. The direct-developing sea urchin Heliocidaris erythrogramma is closely related to indirect-developing sea urchins that develop via a feeding larval stage. Superficial consideration would suggest that simple heterochronies resulting in loss of larval features and acceleration of adult features could explain the substitution of direct for indirect development. However, our experiments show that early development has in fact been extensively remodeled, with modified localization of maternal determinants coupled with dissociation of cell cleavage from axis formation resulting in novel patterns of cell lineage differentiation and fate map. Gene expression has undergone concomitant changes.

Animals↗
PubMed2026

Transcriptomic and metabolomic analyses revealed the action mechanism of nesfatin-1 gene on glucolipid metabolism during early development stage of largemouth bass.

Nesfatin-1 has biological roles including the suppression of food intake and the regulation of glucose and lipid metabolism. However, the information available regarding nesfatin-1 in the glycolipid metabolism in the early development stage of fish is still limited. In order to investigate the role of the nesfatin-1 gene in the early development stage of the largemouth bass (Micropterus salmoides), the nesfatin-1 gene was knocked down using siRNA interference technology. Then, we evaluated its mRNA expression levels, transcriptomes and metabolomes. The mRNA expression levels of nesfatin-1 gene were appreciably decreased at 48 h, 72 h and 96 h after injection of nesfatin-1 siRNA in the early development stage. The omics results revealed that knockdown of the nesfatin-1 gene induced 1833 differentially expressed genes (DEGs) and 2370 differentially expressed metabolites (DEMs). Bioinformatic analysis enriched the most affected molecular pathways (sphingolipid metabolism, fatty acid elongation, amino sugar and nucleotide sugar metabolism and biosynthesis of unsaturated fatty acids) and metabolic pathways (biosynthesis of unsaturated fatty acids, sphingolipid metabolism and amino sugar and nucleotide sugar metabolism) in early development stage of largemouth bass. In amino sugar and nucleotide sugar metabolism, increased expression levels of genes such as chic, chs1, and gck genes, alongside decreased expression levels of the chia.1 gene, resulted in significantly elevated concentrations of N-Acetyl-D-glucosamine, β-d-fructose 6-phosphate, β-d-Fructose, D-mannose 6-phosphate, d-glucose, d-glucose 1-phosphate, UDP-glucose, and UDP-glucuronate, whilst the concentration of UDP-N-acetyl-α-D-glucosamine was markedly reduced. Therefore, the nesfatin-1 gene may influence the early development stage of largemouth bass by affecting signaling pathways associated with glycolipid metabolism. Our findings further expand the understanding of molecular mechanisms of the nesfatin-1 gene, and provide further theoretical support for the initial breeding and feed adaptation of largemouth bass.

Animals↗
PubMed1979

Tissue-specific changes in nuclear RNA content during early development of Triturus vulgaris.

During early development of Triturus vulgaris, as a measure for nuclear activity in neuroectoderm, mesoderm and endoderm, nuclear RNA content was determined by cytochemical methods. In the first stages of gastrulation, that is to say during the early phase of neural induction, the RNA content of the inducing system is considerably higher than in the reacting system. Then, with a phase-shift of about 10 h, the RNA content of the neuroectoderm increases quickly also. In the following stages the nuclear RNA content of both regions is reduced. A second continuous increase in the RNA amount coincides with the formation of the neural tube. In the mesoderm, enhancement of RNA content correlates with cytodifferentiation of the chorda. In all stages the RNA content of the endoderm is higher than in the other tissues and it becomes successively diminished from the early gastrula to the tailbud stage.

Animals↗
PubMedDate not supplied

Behavioral consequences in rats from chronic exposure to 10 PPM halothane during early development.

Albino rats were chronically exposed for 40 hours a week to 10 ppm halothane in air during early development (conception to day 60), adult life (day 60 to day 135), or both. An unexposed group served as a control. Rats exposed during early development made 30 percent more errors than rats unexposed during this period when tested on a shock-motivated visual-discrimination task, or a food-motivated spatial-discrimination task. However, the relative rate of learning was the same for all groups. Exposure during early development also lowered the jump and flinch thresholds to electric footshock as compared to animals not so treated.

Age Factors↗
PubMed1975

Microtubule protein pools in early development.

Microtubule protein pools have been demonstrated to exist in unfertilized eggs and the early embryonic stages of several organisms. The microtubule pool of the sea urchin embryo is constant in size (about 0.4% of the total embryo protein) throughout early development. Protein withdrawn from this pool for organelle assembly is replaced by new synthesis. Eggs and embryos of Drosophila similarly contain a pool of microtubule proteins (larger than or equal to 0.4% of the total embryo protein, congruent to 3% of the soluble protein), which is constant in size throughout early development. The Drosophila egg microtubule proteins are easily purified by self-assembly in vitro of microtubules, and are similar to microtubule proteins from other organisms in molecular weight and other properties. Synthesis of microtubule proteins in sea urchin embryos is supported by oogenetic mRNA. This appears also to be the case in molluscan (Ilyanassa) embryos. It is not known whether Drosophila embryos synthesize microtubule proteins during the early stages of development.

Animals↗
PubMed1992

Mitochondrial DNA content and mitochondrial gene transcriptional activities in the early development of loach and goldfish.

The mitochondrial DNA (mtDNA) content of the mature eggs and embryos of loach and goldfish at early developmental stages were detected by means of dot hybridization. The transcription of mitochondrial cytochrome oxidase subunit I and II (COI and COII) genes during their early development was also detected by Northern hybridization. The experimental results showed that the mtDNA content of the mature egg as well as that of the embryos during the period from fertilized egg up to hatching stage in both fishes is maintained at a constant level, giving an average value of 7.40 x 107 molecules or 1.33 ng for every embryo in loach and an average value of 1.87 x 10(8) molecules or 3.31 ng for every embryo in goldfish. In both fish embryos, the COI and COII transcripts declined gradually after fertilization until late-blastula stage and then increased in early gastrula stage. This indicated that the transcription of mitochondrial genomes of these two freshwater fishes, which belong to different families, might be activated at the beginning of gastrulation. The steady-state amounts of mitochondrial messenger transcripts existing in the embryos during the early development in both fishes seemed to be regulated by both their half-lives and the transcriptional level of the mitochondrial genomes. The results showed that the transcription of the mitochondrial genome in the early developmental process in loach and goldfish was not regulated by a gene dosage mechanism.

Animals↗
PubMed1992

Early development and X-chromosome inactivation in mouse parthenogenetic embryos.

Early development and X-chromosome inactivation were studied in ethanol-induced mouse parthenogenones. About 24% of oocytes transferred to 0.5-day pseudopregnant recipients successfully implanted. However, only 49%, 20%, and 16% of implanted parthenogenones survived 5, 6, and 7 days later, respectively. Abnormal development was evident in every parthenogenone as early as 5 days after activation with the degenerating polar trophectoderm. These embryos were destined to become either small disorganized embryos or embryonic ectoderm vesicles bounded by the visceral endoderm. Only 2 of 51 representative 6- to 8-day parthenogenones sectioned had morphology of the normal egg cylinder, although growth retardation was evident. Spontaneous LT/Sv parthenogenones shared similar morphological features. In late blastocysts, the frequency of cells with an apparently inactivated X chromosome was lower in parthenogenones than in fertilized embryos. The failure of X-inactivation in the trophectoderm seems to contribute to the defective development of parthenogenones.

Animals↗
PubMed1975

The early development of haploid and aneuploid parthenogenetic embryos.

The early development of parthenogenetically activated oocytes had been studied in C57BL X CBA-T6T6 (F1T6) translocation heterozygote mice and C57BL X CBA-LAC (F1LAC) mice. All F1T6 oocytes had either a quadrivalent or a univalent-trivalent configuration at meiosis I; no such chromosome configurations were observed in the F1LAC oocytes. At ovulation 36-5% of the F1T6 oocytes had 19 or 21 chromosomes, whereas 97% of the F1LAC had the normal haploid chromosome number of 20. After parthenogenetic activation, chromosome counts at metaphase of the first cleavage mitosis were made of the eggs with a single pronucleus following extrusion of the second polar body. These activated eggs had similar frequencies of 19, 20 and 21 chromosomes as had the oocytes at ovulation. The activated 1-cell eggs were transferred to the oviducts of pseudopregnant recipients and the embryos recovered 3 days later. At this stage of development, most of the F1T6 embryos with 19 chromosomes were no longer found, but the frequency of 21-chromosome embryos was similar to the frequency of 21-chromosome oocytes and activated eggs. There was a similar mean number of cells in the embryos with 20 and 21 chromosomes. The results indicate that nearly all the embryos with 19 chromosomes failed to develop, probably beyond the 2-cell stage, whereas oocytes with 21 chromosomes had a similar development of oocytes with 20 chromosomes up to the morula stage.

Aneuploidy↗
PubMed1992

Early development of the human area postrema and subfornical organ.

The first appearance and early development of two circumventricular organs, the area postrema (AP) and the subfornical organ (SFO), were investigated in human embryos and fetuses from the 4th to the 40th gestational weeks (GW). The AP appears very early in development, during the GW 10; its high vascularization can be seen from GW14, and differentiated neurons are observed from GW 16. The SFO is characterized by a late onset of development. It can first be distinguished at GW 17, but it does not attain cytological differentiation until the last weeks of gestation. It is suggested that the AP has important functions during fetal life, which are related to normal fetal weight and growth; in contrast the SFO, which is connected with drinking behavior and salt/water balance, seems to play a less essential role in early fetal life.

Body Weight↗
PubMed1975

The early development of the lymphatic system in mouse embryos.

The early development of the lymphatic system was studied in embryos of an inbred strain of the laboratory mouse. During the first stage of its development the system is represented by a more or less regular series of small and blind-ending outgrowths of the major embryonic veins which develop in a cranio-caudalward direction from the jugular to the pelvic region. As a result of differences in growth rates of adjacent anatomical structures this series of early lymphatic primordia becomes subdivided into 4 singular primordia and 12 groups of primordia. After the constituents of each group of early primordia have fused, 16 isolated lymphatic plexuses (sacs) are formed of which 14 are in bilaterally symmetric and 2 are in a median line position: i.e. bilaterally: (1) the jugulo-axillary lymph sac situated lateral to the anterior cardinal vein and dorsal to the primitive ulnar vein and its major branch, the external mammary vein, (2) the paratracheal lymph plexus situated medial to the anterior cardinal vein, (3) the internal thoracic lymph plexus situated lateral to the thoracic part of the posterior cardinal vein, (4) the thoracic ducts situated medial to the thoracic part of the posterior cardinal vein, (5) the lumbar lymph plexus situated dorso-lateral to the abdominal part of the posterior cardinal vein, (6) the subcardinal lymph plexus and (7) the iliac lymph plexus situated ventro-lateral to the abdominal part of the posterior cardinal vein; and in the median line: (8) the subtracheal lymph plexus situated at the confluence of the pulmonary veins and (9) the mesenteric lymph plexus situated near the confluence of the splenic and the superior mesenteric veins. Except for some openings at the jugulo-subclavian confluence all connections with the veins disappear. From the primordia extensions grow out centrifugally. They invade the surrounding tissues and, in part, fuse with similar sprouts of adjacent primordia. In this way a continuous system of lymph truncs is formed that opens into the venous system at the jugulo-subclavian confluence.

Animals↗
PubMed1992

Changes in whole body concentrations of cortisol, thyroid hormones, and sex steroids during early development of the chum salmon, Oncorhynchus keta.

Significant amounts of cortisol (20 ng/g) and thyroid hormones thyroxine (T4, 20 ng/g) and triiodothyronine (T3, 10 ng/g), as well as estradiol (8 ng/g) and testosterone (4 ng/g), are present in fertilized eggs of chum salmon. Changes in the concentrations of these hormones in the developing embryo and larvae were monitored until after the emergence of the fry from the gravel bed. Cortisol concentrations in the developing embryo fell steadily from 20 ng/g at fertilization to 2.5 ng/g after 3 weeks, increased slightly to 10 ng/g by 1 week before hatching, and maintained this level during the early stages of yolk sac absorption. During the later stages of yolk sac absorption, cortisol concentrations increased markedly and remained at about 30 ng/g until emergence, when they declined to 10-15 ng/g. In contrast, both T4 and T3 levels were stable during early development, decreased gradually during yolk sac absorption, and increased slightly during emergence. Estradiol and testosterone profiles were similar to that of cortisol during early development. Testosterone levels remained low throughout emergence. Likewise, estradiol levels were low during yolk sac absorption but showed a transient increase at the time of emergence. These hormonal changes are discussed in the context of egg development and subsequent downstream migration.

Animals↗
PubMed1992

Observations on the early development of the optic nerve and tract of the mouse.

The early development of the retinofugal pathway of mice has been studied by light and electron microscopic methods in order to define the spatial distribution and the structure of the growth cones as they advance from the eye to the brain. We have studied the relationships of the growth cones to each other, to the glia and, in the older individuals, to the nerve fibers that are already terminating in the brain. We have looked at the rate of advance of the growth cones and have paid particular attention to the changing relationships of the growth cones as they approach the optic chiasm. We have also looked to see whether, at early stages, it is possible to recognise any characteristic features distinguishing the fibers destined to be the thickest in the adult, which come from ganglion cells that are generated among the earliest ganglion cells. In transverse sections through the optic stalk about 50-100 microns behind the eye, the first bundles of fibers are seen on embryonic day 12.5 (E12.5) as a mixture of thin (less than 0.5 micron) axons, thicker growth cones, and fine filopodial and foliopodial extensions. During the next two days, as these bundles in the intraorbital nerve increase in size and number, growth cones can be seen in all of the bundles and in all parts of the bundles. They show only a slight preference for one part of the nerve relative to another, and our material provides no evidence for the view that axons are particularly inclined to follow pre-existing bundles. The structure of the pathway changes significantly as it is traced towards the chiasm, and no section or small stretch of sections can be regarded as representative of the nerve as a whole. As the fibers approach the optic chiasm the growth cones come to lie predominantly close to the pial surface, with the deeper regions occupied almost entirely by fine axons. The change occurs in a region where the glial environment also changes, and where a characteristic neural tube-like organization first becomes recognizable. Here the glial cells lie in a periventricular position and send slender radial processes out towards the subpial surface. The newly invading axons in the early optic nerve taper from a broad growth cone back to an extremely slender axon, less than 0.5 micron in diameter. The tapered region is of the order of 100-300 microns in length and advances through the nerve at approximately 60 microns per hour.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1976

[Histochemical localization of lactate dehydrogenase in blastomeres during early development of the rainbow trout embryo (Salmo irideus Gibb)].

During the early development of the trout egg, some blastomers display a certain activity of the L.D.H., variable according to their position in the embryo. At the morula stage, the histochemical ltion of those blastomeres. On the contrary, during the gastrula stage, the blastomeres which have a high L.D.H. activity concentrate in the deep layer of the germ, in the "embryonic button", and in the germinal ring.

Age Factors↗
PubMed1992

[Observation on the early development of inoculated Brugia malayi microfilariae in mosquitoes].

This paper reports the early development and variation of inoculated Brugia malayi microfilariae in 3 groups of mosquitoes, i. e. young Anopheles sinensis, young Culex quinquefasciatus and old Cx. quinquefasciatus. Significant differences were observed among these groups. Sixty hours after inoculation, the percentage of normally developing filarial larvae in young An. sinensis was 72.3%; the percentage of melanized microfilariae in young Cx. quinquefasciatus was 75.4% and the percentage of filarial larvae which developed abnormally or remained in diapause status in old Cx. quinquefasciatus was 67.1%, each being much higher than that in the other groups. It was suggested that the immune competence of the mosquitoes had influence upon the filarial development. The intensity of the immune response not only varied with the species, but also diminished with the aging of mosquitoes.

Aging↗
PubMed1975

Aspartate aminotransferase activity during early development of chicken embryo.

Aspartate aminotransferase (AAT) activity is studied, employing two different procedures, during early development stages of chicken embryo. ATT activity is steady from pre-streak to the definitive primitive streak stage after which it suddenly increases as growth proceeds. INH or IIH administration in this embryonic system led to almost instantaneous and complete disappearance of AAT activity which could be reversed to 80 percent by treatment with equimolar pyridoxal phosphate. Histochemical studies from the literature support a view that the period of intense differentiation coincides with an increased RNA content. The present study shows more AAT activity per mg wet embryo during the same development stages. Whether this is due to availability of more aspartic acid for pyrimidine is not clear due to possible presence of two AAT activities, the many competing reactions that can use aspartic acid, and in situ conditions during differentiation.

Animals↗