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PubMed1990

[Effect of pigmented epithelium from different developmental stages of chick embryo on cell growth of retinal explants].

The model system to investigate the effect of retinal pigmented epithelium (PE) on the retinal development in vitro has been established in this laboratory. Chick retina separated from 5-day-old embryo (E 5) were cut into strips and explanted on the collagen substratum either in close contact with retinal PE (RPE), or without PE (R). The rates of cell proliferation of retinal strips cultured for 48 hr were measured by the uptake of radioactive thymidine and DNA contents. Both parameters in RPE were increased to values ranging from 137 to 167% when PE was taken from E5 and E6. However PE taken from E7, E8 and E9 had no effect on cell proliferation. The rate of cell proliferation of retina were increased both when separated retina and PE of E5 either from same or from an other eye closely contact again and when retina and PE of E5 were explanted together without separation. However the rates of cell proliferation were remained without much change when a millipore filter existed between retina and PE of E5 as well as the retina was inverted, the ganglion cell layer contacted with PE. The neurite outgrowth from retina explant with and without PE of E5 or E6 were also different. After culture for 24 hr the fiber length of neurite growing in RPE was only 36-39% of that in R. After 48 hr it was about 70% of that in R. This results suggested that the developmental stage of PE and the direct cell-to-cell contact of PE from E5 with photoreceptor layer of retina was important for the retinal cell proliferation. But PE had negative influence on neurite growth of retina in culture.

Animals↗
PubMed1991

Infection by coronavirus JHM of rat neurons and oligodendrocyte-type-2 astrocyte lineage cells during distinct developmental stages.

Primary telencephalic cultures derived from neonatal Wistar Furth rats were able to support the growth of coronavirus JHM if a viable neuronal population was maintained. This occurred under serum-free defined, but not serum-supplemented, growth conditions. The importance of neurons in establishing infections in mixed cultures was confirmed by immunocytochemical and electron microscopic studies. Glia, although more abundant than neurons in these cultures, were less frequently infected during the initial 48 h postinoculation. The two glial lineages present in mixed telencephalic cultures were separated into type-1 astrocytes and oligodendrocyte-type-2 astrocyte (O-2A) lineage cells and individually assessed for their ability to support virus growth. Infection could not be established in type-1 astrocytes regardless of the culture conditions employed, consistent with our previous study (S. Beushausen and S. Dales, Virology 141:89-101, 1985). In contrast, infections could be initiated in selected O-2A lineage cells grown in serum-free medium. Virus multiplication was however significantly reduced by preconditioning the medium with mixed telencephalic or enriched type-1 astrocyte cultures, suggesting that intercellular interactions mediated by soluble factor(s) can influence the infectious process in O-2A lineage cells. This presumption was supported by eliciting similar effects with basic fibroblast growth factor and platelet-derived growth factor, two central nervous system cytokines known to control O-2A differentiation. The presence of these cytokines, which synergistically block O-2A cells from differentiating into oligodendrocytes was correlated with specific and reversible resistance to JHM virus (JHMV) infection. These data, combined with our finding that accelerated terminal differentiation of the oligodendrocyte phenotype confers resistance to JHMV (Beushausen and Dales, Virology, 1985), suggest that the permissiveness of O-2A cells for JHMV is restricted to a discrete developmental stage.

Animals↗
PubMed1980

Interaction between External and Internal Conditions in the Development of Photosynthetic Features in a Grass Leaf: II. REVERSIBILITY OF LIGHT-INDUCED RESPONSES AS A FUNCTION OF DEVELOPMENTAL STAGES.

Lolium multiflorum plants were grown under a low- or high-light regime until third leaves had emerged to one-third their final length and then were transferred to a contrasting light regime. At this stage, the leaf possesses a tissue-age gradient from tip to base; thus, the reversibility of light-acclimated responses as a function of the degree of differentiation was analyzed in individual leaves.Regional responses in the apical, medial, and basal zones of leaves of transferred plants were analyzed before and after light transfer and compared to leaves from plants kept in constant light. Leaves transferred from low to high light showed rapid recovery and attained light-saturated rates and ribulose bisphosphate carboxylase activities equivalent to those of high-light controls. However, fresh or dry weight and chlorophyll content were intermediate between those for the two irradiances. In the reciprocal experiment, the apical leaf zone retained high-light characteristics for maximum photosynthesis, whereas all the other functional parameters adapted rapidly to values characteristic of their low-light counterparts (equivalent foliar zones).On the ultrastructural level, chloroplasts in the apical zone of transferred leaves surpassed their respective constant light controls in absolute membrane content and size. However, a shift to high light induced an increase in plastid volume and, in relative terms, the plastid membrane content was diluted. A shift to low-light treatment led to smaller membrane-dense plastids. The ultrastructural readaptation is realized through differential rates of increase in plastid volume and lamellar content. Proplastids (leaf base), or juvenile plastids having reached an intermediate developmental stage (leaf middle zone) at the time of transfer, took on characteristics of the latter light regime (equivalent to controls).These results provide evidence for rapid reacclimation processes under changing light regimes and suggest a capacity for regional light responses along the leaf.

Journal Article↗
PubMed1995

Expression of the cartilage matrix protein gene at different chondrocyte developmental stages.

Cartilage matrix protein (CMP), a major noncollagenous component of certain types of hyaline cartilage, is synthesized by chondrocytes in a developmentally regulated manner. In this study, we monitored the accumulation of CMP in the developing chicken limb and sternum by immunostaining. In older embryos, the specific extracellular staining was restricted to the resting/proliferative zone of metaphyseal cartilage and to the immediately adjacent hypertrophic cartilage. A lack of staining was observed in the peripheral layers of articular cartilage. Data were compared with the accumulation of CMP mRNA measured by Northern analysis relative to other cartilage-specific messages in cell cultures representing different stages of chondrocyte differentiation, as well as with the steady state mRNA levels in tissue samples. We found a correlation between the gene expression pattern of the in vitro cultures and the one observed in certain in vivo differentiation stages. The high-density mesenchyme culture was utilized as a model for studying the events at early stage I (stage Ia) of chondrogenesis. This culture was characterized by relatively low steady state mRNA levels for cartilage proteins, including the later activation of the CMP gene as compared to type II collagen or link protein genes, and relatively high steady state mRNA levels for type VI collagen and beta-actin. Chicken embryo chondrocyte cultures obtained from sterna of 14-day-old embryos, however, consisted predominantly of stage Ib chondrocytes, and showed high steady state levels for cartilage proteins, but relatively lower levels for type VI collagen and beta-actin mRNAs. In accordance with the in vivo data, a relatively high steady state level was detected for CMP mRNA in cultures of hypertrophic (stage II) chondrocytes. We also performed transient expression assays in the various culture systems to study the role of the promoter upstream and intronic control regions in the tissue- and developmental stage-specific regulation of the CMP gene. We showed that the enhancer worked in a lineage-specific manner, by further stimulating the minimal promoter activity independent of the developmental stage of chondrocytes, while it did not in other tissues. The promoter upstream control regions, however, seemed to play a role in restricting the promoter activity to a certain chondrocyte developmental stage.

Animals↗
PubMed1998

Study and characterization of different developmental stages of Leishmania major.

The complete developmental cycle of Leishmania major in axenic culture was achieved by simply changing the temperature whether sudden from 22 degrees C to 37 degrees C or stepwise 22 degrees C, 29 degrees C and then 37 degrees C. The morphology by light microscopy, GPI isoenzyme pattern and PCR amplification of minicircle of kinetoplast DNA of the different stages were studied. The amastigotes obtained from the foot pads of mice were compared to those obtained from axenic culture. The GPI isoenzyme pattern and the PCR amplification products showed distinct differences between the promastigotes and the amastigotes. The amastigotes of the two sources also showed differences after temperature changes.

Animals↗
PubMed1993

Effect of temperature on the developmental stages of Wohlfahrtia nuba (Diptera:Sarcophagidae).

Total developmental time of flesh flies Wohlfahrtia nuba (Wiedemann) from first larval stage to adult emergence was 34.7, 23.5, 18.7, 13.4 and 13.6 days when reared at 21, 25, 29, 33 and 37 degrees C, respectively. There were no significant differences between both sexes (P > 0.05). The overall mean of the larval duration periods was shorter (P < 0.05) than pupal duration periods. Estimates of the lower developmental threshold temperatures (tL) were 12.8, 14.0 and 13.6 degrees C and the thermal constant (K) were 116.8, 152.2 and 268.2 degree-days for larvae, pupae and total developmental time, respectively. Pupal mortality was low at all temperatures used. The fly reached their maximum weight in pupal and adult stages at 21 degrees C. At all temperatures, the mean weight of pupa and adult was smaller (P < 0.001) in males than in females. The developmental rate, low mortality and greatest weight reached their optimal condition between 21 to 33 degrees C.

Animals↗
PubMed1998

Immunohistochemical analysis of developmental stage of external granular layer neurons which undergo apoptosis in postnatal rat cerebellum.

Some granule neurons naturally undergo apoptosis in the external granular layer (EGL) of the postnatally developing rat cerebellum. We analyzed the developmental stage-specificity of this apoptosis using double staining by in situ nick end labeling and immunohistochemistry against three proteins expressed at specific stages of granule neuron development. The amount of apoptosis of EGL neurons peaked on postnatal day 9. In the 9-day-old rat cerebellum, 54.0% of apoptotic EGL neurons expressed proliferating cell nuclear antigen. On the other hand, 22.2 and 15.4% of apoptotic EGL neurons existed in the postmitotic and premigratory zone defined by expression of TAG-1 and 440 kDa ankyrinB, respectively. Thus, proliferative granule neurons undergo apoptosis more frequently than postmitotic granule neurons in EGL of the developing cerebellum. This suggests that there are developmental stage-specific mechanisms of apoptosis of cerebellar granule neurons.

Age Factors↗
PubMed2006

Molecular analysis of microbial communities identified in different developmental stages of Ixodes scapularis ticks from Westchester and Dutchess Counties, New York.

Ixodes scapularis ticks play an important role in the transmission of a wide variety of pathogens between various mammalian species, including humans. Pathogens transmitted by ticks include Borrelia, Anaplasma and Babesia. Although ticks may harbour both pathogenic and non-pathogenic microflora, little is known about how the diversity of the microflora within ticks may influence the transmission of pathogens. To begin addressing this question, we examined the composition of bacterial communities present in Ixodes scapularis collected from Westchester and Dutchess Counties, New York State, at different developmental and nutritional stages. Genetic fingerprints of bacterial populations were generated by temporal temperature gradient gel electrophoresis (TTGE) separation of individual polymerase chain reaction (PCR)-amplified 16S rRNA gene fragments, followed by DNA sequence analysis for bacterial identification. The fingerprints of the TTGE bands were grouped into five clusters. The most abundant DNA sequence found in all the samples was Rickettsia, followed by Pseudomonas and Borrelia. Ralstonia, Anaplasma, Enterobacterias, Moraxella, Rhodococcus and uncultured proteobacterium were present as well. We also determined the prevalence of Anaplasma phagocytophilum and Borrelia burgdorferi by PCR and DNA sequence analysis. Statistical analyses indicated significant variations in the bacterial communities depending on tick developmental stage and degree of engorgement. We suggest that these two elements affect microbial diversity within the tick and may in turn influence pathogen transmission to humans and animals after tick bite.

Animals↗
PubMed2005

Commentary: developmental stages of forensic psychiatry fellowship training--from theoretical underpinnings to assessment outcomes.

Dr. Pinals' paper provides an excellent foundation for studying the developmental process of forensic psychiatry fellows during their training year. She proposes three stages: (1) transformation, (2) growth of confidence and adaptation, and (3) identification and realization. This commentary compares Dr. Pinals' proposed developmental stages to Margaret Mahler's theory of infant development and to Dr. Lev Vygotsky's social learning theory. Assessment methods to evaluate core competencies suggested by the American Council on Graduate Medical Education (ACGME) and American Board of Medical Specialties (ABMS) are reviewed. A potential survey of forensic psychiatry fellowship program directors to validate Dr. Pinals' proposed developmental model is described.

Achievement↗
PubMed1988

Complement binding by two developmental stages of Leishmania major promastigotes varying in expression of a surface lipophosphoglycan.

The binding of complement by two developmentally distinct stages of Leishmania major has been studied. Noninfective log phase growth (LOG) promastigotes (serum sensitive) activate complement with deposition of covalently bound C3b onto the surface of the parasite. Infective, peanut agglutinin (PNA-) metacyclic stage promastigotes (serum resistant) also bear mainly C3b after incubation in serum, but a major portion of deposited C3 is present as a 110 X 10(3) mol wt C3 fragment. Whereas deposition of C3b on LOG promastigotes is mediated through the alternative pathway. PNA- parasites are unable to activate the alternative pathway in nonimmune serum. C3 is released from the parasite surface by proteolytic cleavage, at a rate which is nearly threefold greater for LOG than for PNA- promastigotes. Immunoprecipitation experiments show that the developmentally regulated lipophosphoglycan is a major C3 acceptor on both LOG and PNA- parasites. These experiments, which are the first to compare the form and processing of complement on infective and noninfective promastigotes of Leishmania, provide a framework for further definition of the differential C3 receptor-dependent uptake and survival of these parasites within mononuclear phagocytes.

Animals↗
PubMed1995

Functional roles of in vivo footprinted DNA motifs within an alpha-globin enhancer. Erythroid lineage and developmental stage specificities.

Transcriptional regulation of the human alpha-like globin genes, embryonic zeta 2 and adult alpha, during erythroid development is mediated by a distal enhancer, HS-40. Previous protein-DNA binding studies have shown that HS-40 consists of multiple nuclear factor binding motifs that are occupied in vivo in an erythroid lineage- and developmental stage-specific manner. We have systematically analyzed the functional roles of these factor binding motifs of HS-40 by site-directed mutagenesis and transient expression assay in erythroid cell cultures. Three of these HS-40 enhancer motifs, 5'NF-E2/AP1, GT II, and GATA-1(c), positively regulate the zeta 2-globin promoter activity in embryonic/fetal erythroid K562 cells and the adult alpha-globin promoter activity in adult erythroid MEL cells. On the other hand, the 3'NF-E2/AP1 motif is able to exert both positive and negative regulatory effects on the zeta 2-globin promoter activity in K562 cells, and this dual function appears to be modulated through differential binding of the ubiquitous AP1 factors and the erythroid-enriched NF-E2 factor. Mutation in the GATA-1(d) motif, which exhibits an adult erythroid-specific genomic footprint, decreases the HS-40 enhancer function in dimethyl sulfoxide-induced MEL cells but not in K562 cells. These studies have defined the regulatory roles of the different HS-40 motifs. The remarkable correlation between genomic footprinting data and the mutagenesis results also suggests that the erythroid lineage- and developmental stage-specific regulation of human alpha-like globin promoters is indeed modulated by stable binding of specific nuclear factors in vivo.

Adult↗
PubMed1998

Coiled body numbers in the Arabidopsis root epidermis are regulated by cell type, developmental stage and cell cycle parameters.

We have used whole mount immunofluorescence labelling with the antibody 4G3, raised against the human snRNP-specific protein U2B", and whole mount in situ hybridization with an anti-sense probe to a conserved region of U2 snRNA, in combination with confocal microscopy, to examine the organization of spliceosomal components throughout the development of the Arabidopsis thaliana root epidermis. We show that the number of coiled bodies, nuclear organelles in which splicing snRNPs and snRNAs concentrate, is developmentally regulated in the Arabidopsis root epidermis. Firstly, there is a progression from a small number of coiled bodies in the quiescent centre and initial cells, to a larger number in the cell division zone, returning to a lower number in the cell elongation and differentiation zone. Secondly, trichoblasts (root-hair forming epidermal cells) have on average 1.5 times more and often smaller coiled bodies than atrichoblasts (hairless epidermal cells). Moreover, we have shown that these differences in coiled body numbers are related to differences in cell cycle stage, cell type and developmental stage, but are not due to differences in nucleolar or general metabolic activity per se. We discuss possible explanations, including a model in which coiled bodies coalesce during interphase, for the developmental dynamics of coiled bodies.

Arabidopsis↗
PubMed2006

Evoecotoxicology: environmental changes and life features development during the evolutionary process-the record of the past at developmental stages of living organisms.

For most of evolutionary history, scientific understanding of the environment and life forms is extremely limited. In this commentary I discuss the hypothesis that ontogenetic features of living organisms can be considered biomarkers of coevolution between organisms and physicochemical agents during Earth's history. I provide a new vision of evolution based on correlations between metabolic features and stage-dependent susceptibility of organisms to physicochemical agents with well-known environmental signatures. Thus, developmental features potentially reflect environmental changes during evolution. From this perspective, early multicellular life forms would have flourished in the anoxic Earth more than 2 billion years ago, which is at least 1.2 billion years in advance of available fossil evidence. The remarkable transition to aerobic metabolism in gastrula-stage embryos potentially reflects evolution toward tridermic organisms by 2 billion years ago. Noteworthy changes in embryonic resistance to physicochemical agents at different developmental stages that can be observed in living organisms potentially reflect the influence of environmental stress conditions during different periods of evolutionary history. Evoecotoxicology, as a multidisciplinary and transdisciplinary approach, can enhance our understanding of evolution, including the phylogenetic significance of differences in susceptibility/resistance to physicochemical agents in different organisms.

Animals↗
PubMed2006

Effects of copper on early developmental stages of Lessonia nigrescens Bory (Phaeophyceae).

Copper effects on the early developmental gametophytic and sporophytic stages of the kelp Lessonia nigrescens were tested in gradients of increasing concentrations of ASV-labile copper. The results demonstrated a high sensitivity to copper of all life-history stages of the alga, where even the lowest tested concentration affected spore release as well as their subsequent settlement. More significant, concentrations higher than 7.87 microg L(-1) totally interrupted the development of the spores after they settle. This effect led to a failure in the formation of male and female gametophytes and, as a consequence, to a complete disruption of the normal life cycle of the kelp. Thus, we suggest that the absence of L. nigrescens from copper-enriched environments results from the high sensitivity of its early life cycle stages, which limits growth and maturation of the gametophytic microscopic phase and, as a consequence, prevents development of the macroscopic sporophytic phase.

Copper↗
PubMed1978

[Cytochemical study of various stages of life cycle of Toxoplasma gondii. 10. Phosphatases in the parasites during developmental stages in cat's intestines].

Several methods of acid and alkaline phosphatese and ATPase detection using both natural and artificial substrates were applied to the intestinal stages of Toxoplasma gondii with negative results to reveal enzymatic activity in all the stages except the microgametocyte. Possible explanation of this unexpected phenomenon is discussed taking into account host-parasite relationships with intestinal stages of Toxoplasma and with coccidia in general.

Acid Phosphatase↗
PubMed1983

Developmental-stage-dependent teratogenic effects of maternal spontaneous diabetes in the chinese hamster.

The effect of maternal diabetes on teratogenesis was examined utilizing female Chinese hamsters with typical diabetic symptoms from our closed colony (CHA) and F13-F19 of the brother-sister mating generations of a diabetic strain (CHAD). Both groups were mated with nondiabetic males from CHA. Embryologic studies on day 2.5, 4.5, and 18.5 of gestation were performed with 30, 31, 71 diabetic females that were impregnated during a normal 4-day estrous cycle. The preimplantation embryos of day 2.5 and 4.5 were also karyotyped. The results indicated that: (1) There was no decrease in the number of ovulated ova, of collected embryos, and of implantation sites in the diabetic females. (2) As far as the preimplantation stages were concerned, there was no decrease in the cleavage activity and no increase in the incidence of developmental anomalies. (3) There was no increase of chromosomal aberrations in the preimplantation embryos. (4) With respect to the postimplantation development, however, there were significant increases in embryonic death (P less than 0.001), gross malformation (P less than 0.001), and fetal hypoplasia (P less than 0.001). Results (1), (2), and (3) indicated that in diabetic females capable of conceiving during a normal estrous cycle, the maternal diabetic milieu did not affect oogenesis, ovulation, fertilization, cleavage division, implantation, and chromosomal behavior. Result (4), however, showed definitely that maternal diabetes exerted deleterious effects on fetal development during the stage of organogenesis, and also markedly reduced fetal growth during later developmental stages.

Animals↗
PubMed1993

The developmental stages of osteoblast growth and differentiation exhibit selective responses of genes to growth factors (TGF beta 1) and hormones (vitamin D and glucocorticoids).

Osteoblasts in vitro undergo a developmental sequence of growth and differentiation characterized by a stage-specific expression of cell growth and bone-related genes. Our studies show that contributions to development of the osteoblast phenotype include: (1) the down-regulation of proliferation, (2) biosynthesis and organization of type 1 collagen extracellular matrix, and (3) mineralization of this matrix. Hormones and growth factors added to isolated osteoblasts during the initial proliferation period can dramatically alter the subsequent program of developmental stages of differentiation. Studies are presented that demonstrate alterations in gene expression in response to: (1) transforming growth factor beta (TGF beta 1), that prevents differentiation of the cells and their ability to form bony tissue-like nodules; (2) glucocorticoids, which induce and accelerate development of the bone-cell phenotype; and (3) the active metabolite of vitamin D, 1,25(OH)2D3, which results in both inhibitory and stimulatory effects of the hormone on growth and differentiation--effects that are dependent upon the differentiated state of the osteoblast. Thus, in the presence of these physiological mediators of bone-cell phenotype development, many of the growth and differentiation relationships operative in osteoblasts are modified or abrogated, precluding expression of the structural and functional properties of mature bone cells and tissue. These findings have significant implications for use of hormones or growth factors in the treatment of disorders where bone is involved.

Animals↗