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PubMed2001

Early development of systems analysis in natural resources management from man and nature to the miami conservancy district.

Contemporary approaches to natural resources and environmental decision-making typically draw on a "systems" perspective to assess and improve management strategies. This paper describes the early genesis of the systems analysis approach. It concentrates on a period between the mid-19th to early 20th centuries. During the early part of this period, George Marsh's Man and Nature and related works laid out an approach to problem-solving that recognized the relationship among physically disperse elements in the environment, the need to balance benefits against costs, the potential for using quantitative modeling to understand management options, and the importance of integrating human and natural components into solutions. In the early 20th century, the Miami Conservancy District project brought this approach to fruition with its use of complex simulation and optimization modeling, detailed cost-benefit analysis, and its linking of economics, engineering, science, and law into a far-reaching solution to a complex water resources problem. The objective of this paper is to describe the early development and application of this conceptual approach to problem-solving. An examination of the origins of natural resources systems analysis can broaden one's perspective of the contemporary field to understand its roots as a philosophy for environmental problem-solving.

Conservation of Natural Resources↗
PubMed1998

Observations on early development of the murine fetal oral vestibule.

Morphological and immuno/histochemical studies were performed on the vestibular lamina (VL) of gestational day 13 murine fetuses, using light microscopy (LM), confocal laser scanning microscopy (CLSM) and transmission electron microscopy (TEM), in an effort to elucidate the early development of the oral vestibule. Histochemistry employing LM demonstrated some PAS-positive glycogen particles in embryonic cells of the VL, dental lamina (DL), the primary epithelial band connecting the VL and DL, and the related stomodaeal simple epithelium. On the other hand, Gomori's aldehyde fuchsine method stained certain cystine-containing intracellular granules and intercellular amorphous substances, particularly in the central VL. Intense immunoreactivity for CK-10 intermediate-sized filament proteins was demonstrated in suprabasal and superficial cells of the VL stratified keratinized epithelium. Conversely, reactions for CK-19 filaments were found diffusely in both VL and DL cells retaining the cytokeratin characteristic of the simple epithelium. TEM of the VL revealed an increment in keratinosomes, tonofilaments and desmosomes in the suprabasal layers shifting toward superficial flat parakeratinized cells. The TUNEL method using CLSM detected programmed cell death in the VL, while TEM provided no morphological evidence of necrosis or typical apoptotic features during VL development. The present results indicate that physiological (naturally occurring) cell death and exfoliation of the oral-gingival type multilayered keratinizing epithelium are essential for degeneration and separation of the VL, ultimately leading to formation of the oral vestibule.

Animals↗
PubMed1983

Distribution of elongation factor 2 between particulate and soluble fractions of the brine shrimp Artemia during early development.

The ADP-ribosylation of elongation factor 2 (EF-2) in vitro was used to quantitate EF-2 and to determine its subcellular distribution in extracts of Artemia embryos at different stages of development. In extracts from dormant cysts of Artemia 40-45% of EF-2 is complexed to macromolecules smaller than ribosomes, whereas the remainder is soluble or free in the cytosol. During early development the amount of "complexed" EF-2 decreases markedly concomitant with an increase in the pool of soluble EF-2. Complexed EF-2 was found to be associated with macromolecules which sediment at 16S-20S and 40S-50S and not with monoribosomes or polyribosomes as reported for mammalian systems. The data show that the decrease in complexed EF-2 is associated with the resumption of development in Artemia.

Animals↗
PubMed1997

Structural abnormalities of autosomal chromosomes in the male partner do not influence fertilization and early development of embryos after intracytoplasmic sperm injection.

The objective of this study was to determine whether or not abnormalities in the autosomal structure of the male partner have any influence on fertilization and early embryo development after intracytoplasmic sperm injection (ICSI). Thirty-seven couples in whom the male partners were examined by the same andrologist were included in this study. Six couples (group I) in whom the male partner possessed autosomal structural abnormality underwent seven ICSI cycles. As a control group, 31 couples (group II) in which the male partner was karyotypically normal underwent 41 ICSI cycles. Although the normal fertilization rates seen in group I were significantly higher than those in group II (P < 0.05), there was no significant difference in the cleavage rates between the two groups. We did not perform the analysis of the female partner's chromosomes, but we surmise that structural autosomal abnormalities in the male partner do not adversely influence fertilization at ICSI and early development of embryos.

Adult↗
PubMed2006

Early development of chick embryo respiratory nervous system: an immunohistochemical study.

The extrinsic and intrinsic respiratory nervous systems receive specific contributions from the vagal and sympathetic components. Using specific markers for vagal and sympathetic structures, we studied the distribution patterns of immunoreactivity to galanin (GAL), pituitary adenylate cyclase-activating polypeptide-27 (PACAP) and the tachykinin substance P in extrinsic and intrinsic nerve of chick embryo respiratory system, during development from the very early age to hatching. All peptides studied appeared in the intrinsic and extrinsic nervous systems early. We found substance P in both the vagal and sympathetic systems, PACAP in vagal components alone and GAL mainly in the sympathetic system. The intrinsic nervous system showed high immunoreactivity for all peptides studied. These data accord with the well known early trophic functions that peptides have on the development of nervous networks and modulatory activity on the intrinsic nervous system. The GAL again proves to be the main peptide in chick embryo sympathetic respiratory system.

Animals↗
PubMed1975

[Studies on the effects of dental amalgam upon the fertilization and early development of sea urchin eggs (Hemicentrotus pulcherrimus) (author's transl)].

Silver-tin amalgam that has been used as a filling material in routine dental clinic contains a large amount of mercury and the cytotoxity of metal mercury may hazard to patients. There have been a number of papers reporting that the dental amalgam has not any toxic action to living cells in animal experiments in vivo. However, the mechanism of cytotoxic action and effects of these metals for tissues and cells were not reported so far. In the present experiments, the analysis of the cytotoxic action of silver-tin alloys and their amalgam in vitro cytological experiments with fertilized eggs and developing embryos of sea urchin, Hemicentrotus pulcherrimus, were examined. When the silver-tin alloy powder was incubated in normal sea water medium there are non or weak cytotoxic reaction upon fertilized eggs and early embryos of sea urchin. Metal mercury in the medium effects remarkable cytotoxic action upon the development of early embryos; the cleavage and early development were delayed and all of the embryos show deformity. Immediately after the alloy powder was triturated with mercury, it shows strong cytotoxic action as the metal mercury was incubated, however, the cytotoxic action decreased and almost disappeared in 5 hours after trituration. The mechanism of cytotoxic action and the adequacy of clinical application of the amalgam were discussed.

Animals↗
PubMed1985

Histone messenger RNA synthesis and accumulation during early development in the echiuroid worm, Urechis caupo.

RNA isolated from Urechis caupo mature oocytes and embryos was analyzed for the presence of histone messenger RNAs (mRNAs) by in vitro translation and by filter blot hybridization to determine the contribution of maternal and newly transcribed histone mRNAs to the pattern of histone synthesis during early development. Histone mRNAs were not detected in mature oocyte RNA which suggests that relatively few if any maternal histone mRNAs are sequestered in the mature oocytes. Histone mRNAs were detected in cleavage-stage RNA and increased in amount from midcleavage through late gastrula stages. The in vitro translation analysis also demonstrated that the amount of H1 histone mRNA in late cleavage- and early blastula-stage embryos exceeds that of the individual core histone mRNAs. The disproportionate accumulation of individual histone mRNAs correlates with the noncoordinate synthesis of H1 and core histones which occurs during early embryogenesis.

Animals↗
PubMed2006

Four-dimensional imaging and quantification of gene expression in early developing zebrafish (Danio rerio) embryos.

Four-dimensional (4D) imaging is a powerful tool for studying three-dimensional (3D) changes in an organism through time. Different imaging systems for obtaining 3D data from in vivo specimens have been developed but usually involved large and expensive machines. We successfully used a simple inverted compound microscope and a commercially available program to study and quantify in vivo changes in sonic hedgehog (shh) expression during early development in a green fluorescence protein (GFP) transgenic zebrafish (Danio rerio) line. We applied the 4D system to study the effect of 100 microM cadmium exposure on shh expression. In control zebrafish embryos, shh:GFP expression was detected at about 9 h post-fertilization (hpf) and increased steadily in the next 7 h, peaking at about 17 hpf and decreasing in the following 4 h. In the same time period, different shh expression volumes were observed in cadmium-treated and control embryos. Embryos affected by cadmium-exposure demonstrated a down-regulation in shh expression. The number of GFP-expressing cells measured by flow cytometry decreased, and expression of neurogenin-1, a downstream target of the shh signaling pathway, was down-regulated, providing additional supporting data on the effects of cadmium on shh. In summary, we demonstrated the setup of a 4D imaging system and its application to the quantification of gene expression.

Animals↗
PubMed1997

A functional analysis of p53 during early development of Xenopus laevis.

p53 is a nuclear protein that acts like a tumor suppressor and is involved in regulation of cellular growth. In Xenopus, the p53 protein is highly expressed during oogenesis and is strictly cytoplasmic in the oocyte. We have analysed its participation in DNA replication and transcription during early development, using the egg and oocyte as model-systems. The injection of sperm nuclei into Xenopus eggs is followed by DNA replication and mitotic events. We show that the endogenous p53 enters the nuclei and moves through a series of discrete sub-nuclear loci whose distribution is S-phase specific. A specific peripheral nuclear localization of p53 is observed before entry into S-phase, followed by an internal localization which is strictly dependent on ongoing DNA synthesis. At no stage in the cell cycle, however, did we observe any co-localization with RPA or PCNA, which were used as initiation or elongation markers for DNA replication. We also show that injection into the nucleus of the oocyte of small amounts of either Xenopus or human p53 - less than 10% of the cytoplasmic storage - is sufficient to block RNA polymerase II-dependent transcription from a coinjected TATA-box-containing reporter plasmid. Transcription is rescued by microinjection of the TATA-box binding protein (TBP), suggesting that nuclear exclusion of p53 during oogenesis may be necessary for transcription of maternal genes. These characteristics are discussed in relation to the regulation of nuclear activities during early embryogenesis.

Animals↗
PubMed1981

Genetically associated similarities and differences in the generation of neurons comprising an early developing reflex pathway in mouse spinal cord.

Tritiated thymidine autoradiography has been used to study the generation of lateral motor neurons (LMNs), association interneurons (ANs) and dorsal root ganglion cells (DRGNs) in the spinal cords of genetically diverse strains of mice. The neuronal populations analyzed in this study form an early developing reflex pathway and the ontogeny of this circuit exhibits genetically associated variability. The strains of mice used in this investigation have been shown to differ in the embryonic age at which forelimb reflex movements are first manifest and in the timing of synapse formation within the reflex pathway. A precocious development of these reflex traits occurs in strain C57BL/6J in comparison to embryos of intermediate (CBA/CaJ) and late developing (LP/J) strains. All three inbred strains show the same basic generation sequence for the neuronal populations comprising the forelimb reflex pathway. The generation of LMNs precedes that of ANs, and the generation of ANs, in turn, precedes that of DRGNs. Since this is the same sequence as that observed for the formation of synaptic junctions in all three strains, it is suggested that synaptogenic sequences in reflex circuits may be determined by the generation sequence of the component neuronal populations. Although the strains all exhibit the same basic sequence of neuronal generation, the temporal relationships of the generation of each cell population within this sequence show significant strain dependent variations. C57BL/6J displays a larger temporal separation between the generation of each cell type than LP/J, and CBA/CaJ is intermediate to the other two strains in this respect. The fact that this strain order is identical to that observed for the development of reflex traits suggests that genetically associated differences in the timing of neuronal birthdays within a common generation sequence may have a substantial influence on the timing of synaptogenesis within the reflex pathway.

Animals↗
PubMed1977

Early development of X-cells in kitten lateral geniculate nucleus.

Lateral geniculate nucleus cells of the kitten were classified as X-cells or Y-cells with a contrast reversal test and their latencies to optic chiasm shock were measured. X-cells with mature latencies were found as early as 21 days. Y-cells did not have adult latencies at 40 days. The early development of some X-cells may be due to differential rates of fiber myelination and synaptic maturation within the lateral geniculate nucleus.

Age Factors↗
PubMed2005

Effect of beta-mercaptoethanol during in vitro fertilization procedures on sperm penetration into porcine oocytes and the early development in vitro.

This study was carried out to determine the effects of beta-mercaptoethanol (bME) during a transient co-culture of gametes for 10 min, and/or the following culture until 6-9 h after insemination, on sperm penetration of porcine in vitro maturation (IVM) oocytes and the early development in vitro. When fresh spermatozoa were cultured in various concentrations of bME for 2 h, bME neutralized the stimulatory effect of caffeine-benzoate on sperm capacitation and the spontaneous acrosome reaction at 50-250 micromol/l. When 50 micromol/l bME were added during a transient co-culture of gametes for 10 min, the sperm penetration rate was reduced 9 h after insemination (70.5-82.0% vs 90.5-94.0% in the absence of bME), but the incidence of monospermic penetration was not affected. When 50 micromol/l bME were supplemented during culture after a transient co-culture, the sperm penetration rate was not affected, but the incidence of monospermy oocytes was increased (43.9-45.8% vs 31.7-34.3% in the absence of bME). The presence of bME following a transient co-culture minimized a decrease of oocyte glutathione content at 6 h after insemination (7.9 pmol/oocyte before in vitro fertilization (IVF), 6.7 pmol/oocyte in the presence of bME vs 5.5 pmol/oocyte in the absence of bME). When the distribution of cortical granules was evaluated 1 h after activation with calcium ionophore, mean pixel intensity of fluorescein isothiocyanate-labeled peanut agglutinin (FITC-PNA) at the cortex region was lower in the oocytes activated and cultured in the presence of 50 micromol/l bME. Although the presence of 50 micromol/l bME during a transient co-culture for 10 min and the following culture did not increased blastocyst formation (29.6-37.7%), 50 micromol/l bME during the following culture significantly increased the mean cell numbers per blastocyst (73.3-76.4 vs 51.2 in the presence and absence of bME respectively). These results demonstrate that supplementation with bME during IVF procedures, except during a transient co-culture period of gametes in the presence of caffeine, has a beneficial effect in maintaining the function of gametes, the incidence of normal fertilization and, consequently, the quality of IVF embryos.

Animals↗
PubMed1987

The development of an assay to detect mRNAs that affect early development.

We have constructed an assay to identify developmental effects of injected RNA molecules. The RNA is injected into the animal pole region of a 2- to 8-cell embryo. At the blastula stage, the animal cap is removed and its development in isolation tested. In controls, only epidermis is produced, but several of the injected RNA preparations, though not all, also form dorsal and ventral mesoderm and nervous tissue. This assay should be suitable for selecting cDNA clones complementary to mRNAs that direct development.

Animals↗
PubMed1982

Development of the optic nerve in Xenopus laevis. I. Early development and organization.

Development of the Xenopus laevis optic nerve was studied by light and electron microscopy from embryonic stage 26, before the retina has formed, to juveniles, 8 months postmetamorphic. Low-power EM photographs of sections through the retinal optic nerve (RON), middle optic nerve (MON) and chiasmatic optic nerve (CON) were prepared at different stages and the areas containing large axons (0.5 micron) were traced in optic nerve reconstructions. Ordering of fibre size along a dorsoventral axis was noted in the embryonic nerve, and this pattern persisted throughout development. Most large fibres, myelinated and unmyelinated, occupy an eccentric dorsocentral position in the MON while small axons are seen in a ventral peripheral crescent. In the CON, the dorsal one third to one half is occupied by large fibres while the ventral CON contains small fibres exclusively. If, as assumed, large axons are older than small axons (0.1-0.3 micron), then patterns of large and small axons along the nerve might reveal a chronotopic fibre ordering. Chronotopic ordering was confirmed by autoradiographic analysis of the distribution of old, labelled fibres and young, unlabelled newly arriving fibres in optic nerves between stage 51 and 57. The young-old labelling pattern corresponds to the small and large axon patterns respectively, in all sections of the optic nerve. Chronotopic ordering of fibres in the developing optic nerve can be explained, in part, by the dorsoventral asymmetric marginal growth of the developing retina and the phenomenon of fibre following as ganglion cell axons join near neighbour fascicles in the retina, converge at the optic disc and grow through the optic nerve.

Animals↗
PubMed1995

Roles of hepatocyte growth factor/scatter factor and the met receptor in the early development of the metanephros.

Several lines of evidence suggest that hepatocyte growth factor/scatter factor (HGF/SF), a soluble protein secreted by embryo fibroblasts and several fibroblast lines, may elicit morphogenesis in adjacent epithelial cells. We investigated the role of HGF/SF and its membrane receptor, the product of the c-met protooncogene, in the early development of the metanephric kidney. At the inception of the mouse metanephros at embryonic day 11, HGF/SF was expressed in the mesenchyme, while met was expressed in both the ureteric bud and the mesenchyme, as assessed by reverse transcription PCR, in situ hybridization, and immunohistochemistry. To further investigate the expression of met in renal mesenchyme, we isolated 13 conditionally immortal clonal cell lines from transgenic mice expressing a temperature-sensitive mutant of the SV-40 large T antigen. Five had the HGF/SF+/met+ phenotype and eight had the HGF/SF-/met+ phenotype. None had the HGF/SF+/met- nor the HGF/SF-/met- phenotypes. Thus the renal mesenchyme contains cells that express HGF/SF and met or met alone. When metanephric rudiments were grown in serum-free organ culture, anti-HGF/SF antibodies (a) inhibited the differentiation of metanephric mesenchymal cells into the epithelial precursors of the nephron; (b) increased cell death within the renal mesenchyme; and (c) perturbed branching morphogenesis of the ureteric bud. These data provide the first demonstration for coexpression of the HGF/SF and met genes in mesenchymal cells during embryonic development and also imply an autocrine and/or paracrine role for HGF/SF and met in the survival of the renal mesenchyme and in the mesenchymal-epithelial transition that occurs during nephrogenesis. They also confirm the postulated paracrine role of HGF/SF in the branching of the ureteric bud.

Animals↗
PubMed1993

Expression of two distinct homologues of Xenopus Max during early development.

The Max protein belongs to the basic region-helix-loop-helix-leucine zipper family of transcriptional regulators. Max heterodimerizes with Myc family proteins to form sequence-specific DNA-binding complexes. In order to elucidate the potential role of Myc and Max during amphibian embryogenesis, we have isolated and analyzed the expression of two Xenopus Max complementary DNAs: XMax1 and XMax2. Comparison of XMax1 and XMax2 with their mammalian counterparts demonstrates a strikingly high degree of conservation at both the nucleotide and amino acid levels, with the exception of a 24-residue deletion in both XMax proteins within their COOH termini. In addition, the two Xenopus Max proteins differ in that XMax2 contains a unique 27-amino acid insertion that interrupts the COOH-terminal end of the zipper domain; XMax1 lacks this insertion. Despite these differences, both XMax1 and XMax2 can form complexes with either Xenopus or human c-Myc proteins. Analysis of XMax expression during embryogenesis reveals that both mRNA and protein are expressed throughout early development, including the egg, 32-cell stage, and midblastula transition. Although the expression of XMax1 RNA appears to predominate at all stages examined, the ratios of XMax1 to XMax2 protein vary during development as well as between different tissue culture cell lines, suggesting a potential for cell type-specific regulation. Our results demonstrate the presence of Xenopus Max throughout frog development, raising the possibility that Myc and Max could function as a complex even during early embryogenesis.

Amino Acid Sequence↗
PubMed1995

pDcsA vectors for strictly regulated protein synthesis during early development of Dictyostelium discoideum.

Two expression vectors have been constructed to express proteins exclusively in developing cells of Dictyostellium discoideum. In these Escherichia coli/D. discoideum shuttle vectors, proteins are synthesized under control of the promoter of the contact site A (csA) gene, which is efficiently suppressed during growth and becomes strongly activated during early development of D. discoideum. The pDcsA vectors appear to be valuable tools for the production of proteins that are not compatible with growth of D. discoideum cells.

Ampicillin Resistance↗