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Results for “Developmental stage”

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PubMed2001

Developmental stage sensitivity and mode of action information for androgen agonists and antagonists.

The response from exposure to a toxic agent during development may vary depending on the dose, time of exposure and the mode of action. The mode of action and developmental stage sensitivity are established only for a limited number of chemical classes. Some aspects of developmental stage sensitivity that appear to affect the response to androgen agonists and antagonists are the levels and distribution of endogenous androgens and the androgen receptor at particular times during development. This information is summarized and discussed as it relates to two critical windows of development: the period of male reproductive tract differentiation, and the peripubertal period when male sexual maturation occurs. Developmental stage sensitivity and mode of action data for the androgen antagonist vinclozolin are reviewed. Vinclozolin acts by binding to and activating the androgen receptor and affects a number of endpoints of reproductive tract differentiation as well as pubertal maturation. Approaches to incorporating mode of action, developmental stage sensitivity, and dose/potency information into risk assessment, as well as the additional data needed for using mode of action information, both qualitatively and quantitatively, in risk assessment are discussed. These issues are also considered in the context of combining the risks of exposure to two or more chemicals with similar modes of action.

Aging↗

PubMed1985

Electrophoretic patterns of proteins from Paragonimus westermani in early developmental stages.

In order to observe the protein compositions of soluble extracts of P. westermani, and their changes during early developmental stages, the crude saline extracts of 4, 6, 8, 10 and 12 week-old worms which were harvested from experimentally infected dogs were analysed by disc-PAGE. The results were as follows: A total of 15 bands were identified from electrophoregrams of respective developmental stages. Of them, 5 bands were recognized throughout the developmental stages. The number and protein amount of identified bands changed according to the worm development from 4 weeks to 12 weeks. However, the banding patterns of 4 and 6 week-old worms and 8 and 10 week-old worms were similar each other. Of 15 identified bands, band 1 was recognized only in 12 week-old worms whereas bands 3, 4, 8, 9, 10, 11 and 15 gradually lowered their amount according to development to disappear in 12 week-old. In addition, band 5 became a major band in 12 week-old while band 6 turned to a minor band at tha same age. The possible relations of changing patterns of protein bands with worm development were discussed.

Journal Article↗

PubMed2001

The expression of substance P and its neurokinin-1 receptor mRNA in the bovine corpus luteum of early developmental stage.

Related to all leukocytes, 90% of eosinophils are recruited into the bovine corpus luteum of early developmental stage. We here describe a simultaneous appearance of substance P (SP)-positive fibre-like structures and the neurokinin-1 (NK-1) receptor mRNA for SP. Substance P was depicted by using indirect immunohistology and immunofluorescence localization. The dot blot analysis confirmed the presence of SP at the protein level. Using nested reverse transcribed-polymerase chain reaction (RT-PCR) analysis, a 358 bp long partial bovine receptor mRNA for SP (NK-1) was sequenced in the spinal cord. The mRNA for SP and for the NK-1 receptor were then detected in the corpus luteum of early developmental stage with RT-PCR and nested RT-PCR. We conclude: The production of SP and the expression of NK-1 receptor mRNA may be involved in the selective recruitment of eosinophils into the bovine corpus luteum of early developmental stage.

Animals↗

PubMed2004

[Gene expression of angiogenesis-related factors in fetal skin at different developmental stages and childhood skin].

OBJECTIVE: To explore the change in gene expression of angiogenesis-related factors vascular endothelial growth factor (VEGF), angiopoietin-1 (Ang-1), acid fibroblast growth factor (aFGF) and basic fibroblast growth factor (bFGF), in fetal skin at different developmental stages and children skin and their potential biological significances. METHODS: Fetal skin samples of human embryo were obtained from spontaneous abortion at different gestational ages ranging from 13 to 32 weeks, and children skin specimens were collected from child patients (4-12 years) undergoing plastic surgery. After morphological characteristics of skin at different developmental stages were defined histologically gene expressions of VEGF, Ang-1, aFGF and bFGF were examined with reverse transcription-polymerase chain reaction analysis (RT-PCR). RESULTS: The trend of changes in gene expression of VEGF, Ang-1, aFGF and bFGF was not same for different skin specimens at various developmental stages. In early gestational fetal skin, genes of VEGF and Ang-1 were strongly expressed, while in late gestational and childhood skins, gene expressions of VEGF and Ang-1 were apparently decreased. In skin of middle gestational stage, the level of aFGF gene expression was highest, and then it was progressively reduced. In childhood skin, this gene was weakly expressed. In marked contrast, the contents of transcripts of bFGF showed no substantial change in fetal skin at different developmental stages, whilst the mRNA content of bFGF was significantly decreased in childhood skin. CONCLUSION: VEGF, Ang-1, aFGF and bFGF might be involved in regulating angiogenesis in skin from fetuses of different gestational stages and children. The relative increase in gene transcription of VEGF and Ang-1 in younger fetal skin might be one of the reasons why cutaneous cells proliferate rapidly and the wounds heal without scar.

Angiogenic Proteins↗

PubMed2000

Evidence that resistance in squash mosaic comovirus coat protein-transgenic plants is affected by plant developmental stage and enhanced by combination of transgenes from different lines.

Three transgenic lines of squash hemizygous for the coat protein genes of squash mosaic virus (SqMV) were shown previously to have resistant (SqMV-127), susceptible (SqMV-22) or recovery (SqMV-3) phenotypes. Post-transcriptional gene silencing (PTGS) was the underlying mechanism for resistance of SqMV-127. Here, experiments conducted to determine the mechanism of the recovery phenotype and whether enhanced resistance could be obtained by combining transgenes from susceptible and recovery plants are reported. Upper leaves of SqMV-3 plants were sampled for Northern analysis at 17, 31 and 45 days after germination (DAG) and a proportion of plants were inoculated with SqMV. SqMV-3 plants inoculated at a young stage (17 DAG) showed susceptible or recovery phenotypes. However, a number of plants inoculated at later developmental stages (31 or 45 DAG) were resistant to infection. Resistance of recovery plants was due to PTGS that was activated at a later developmental stage, independent of virus infection. Similar results were observed with plants grown under field conditions. To investigate the interactions of transgenes, progeny of crosses between SqMV-127, -3 and -22 were inoculated with SqMV. Progeny with the transgene of line 127 were resistant. However, a number of plants with transgenes from the recovery and susceptible lines or the self-pollinated recovery line were resistant even when inoculated at a young stage. Northern analysis suggested that resistance was due to PTGS. The results reveal that the timing of PTGS and consequent resistance of the transgenic plants were affected by their developmental stage and the interaction of transgene inserts.

Blotting, Northern↗

PubMed2006

The length of the humerus in human embryos at developmental stages 18-23.

The length of the humerus was measured in 69 staged human embryos at developmental stages 18-23 (7 and 8 weeks). It was found that the length of the humerus increases from 2.0 mm at stage 18 to 5.4 mm at stage 23. There were slight variations at certain of the stages investigated. Asymmetry between limb lengths was not found during the embryonic period under examination.

Anthropometry↗

PubMed1983

Steroid production by Xenopus ovarian follicles at different developmental stages.

Xenopus ovarian follicles at different developmental stages were compared with respect to their capacity to produce and secrete steroids and to respond to gonadotropic hormones with changes in steroid production. Individual follicles were obtained by treating ovaries with collagenase and were incubated for 10 hr in incubation medium alone or in medium containing a Xenopus pituitary homogenate (FPH, 0.04 pituitary/ml). At 10 hr oocytes were scored for meiotic maturation and ovulation and incubation media and follicles were collected separately and frozen. Both tissue and media were measured for progesterone, testosterone, and estradiol by radioimmunoassay. The smallest follicles (Dumont Stages I and II) secreted very low or nondetectable levels of these three steroids in both the presence and absence of FPH. Medium-sized follicles (Stages III and IV) were active in secreting estradiol and FPH stimulated a twofold increase in the accumulation of estradiol in the incubation medium. In follicles larger than Stage IV, estradiol secretion decreased as follicular size increased. In contrast, large follicles (Stages V and VI) secreted much more testosterone and progesterone than medium-sized follicles and FPH significantly increased the accumulation of these two steroids. Overall, follicular secretion of testosterone was much greater than secretion of progesterone or estradiol. The concentration of the three steroids in the ovarian follicles at 10 hr of incubation followed patterns that were similar in general to the patterns of accumulation of steroids in the incubation medium. Ovine LH, but not FSH, was effective in stimulating secretion of the three steroids and in triggering meiotic maturation of oocytes in Stage VI follicles. Although many of the morphological and biochemical events of oogenesis and folliculogenesis in Xenopus have been described, this is the first report of the developmental pattern of steroid production. The data indicate that growth and development of Xenopus follicles are accompanied by shifts in steroidogenic abilities, with estradiol produced by medium-sized follicles and androgen and progesterone secreted by large follicles.

Animals↗

PubMed1983

Analysis of antigens from different developmental stages of Angiostrongylus cantonensis.

Protein profiles of somatic extracts from different developmental stages and excretory and secretory products of third-state larvae of Angiostrongylus cantonensis were analyzed and characterized by polyacrylamide gel electrophoresis in sodium dodecyl sulfate under both reduced and unreduced conditions. Immunological identification of common and stage-specific antigens was determined by radioimmunoprecipitation using chronically infected rat serum and antisera from rats immunized with somatic extracts of third-stage larvae and adult female worms. The somatic extracts of first-and third-stage larvae and of adult worms were found to be highly complex, each consisting of more than 20 different peptides with molecular weights varying from higher than 130,000 to 8,200 daltons. Most proteins were composed of single polypeptide chains. Polypeptides with molecular weights of 80,000, 39,500 and 22,000 daltons were present in more than one developmental stages and were antigenically related. Those with molecular weight of 15,500 dalton, was present primarily in L3S and its possible usefulness in immunodiagnosis of infection that occurs in man was discussed.

Angiostrongylus↗

PubMed2004

Adolescent adjustment in a nationally collected sample: identifying group differences by adoption status, adoption subtype, developmental stage and gender.

The current study investigated group differences in adolescent adjustment by adoption status and adoption subtype in a national sample, in contrast to group differences based on developmental stage or gender. Secondary analyses of the National Longitudinal Study of Adolescent Health were performed to describe group differences in a broad range of adjustment measures (a) between adoptees and non-adoptees, (b) between different-race adoptees and same-race adoptees and, (c) across adolescent developmental stage and gender groups. Based upon a developmental deviance hypothesis, the current study hypothesized that early adolescent different-race adoptees would fair better across measures of academic performance, familial relationships, psychological adjustment, and physical health than their middle and late adolescent counterparts. Group comparisons revealed little evidence of increased maladjustment among adopted adolescents compared to non-adopted study participants. In addition, group comparisons revealed few differences across indices of adolescent adjustment by adoption subtype (i.e. by the degree of racial congruence adopted child and adoptive parent). However, significant group differences in adolescent adjustment were found based on participants' developmental stage and gender. The implications of the findings are discussed.

Adaptation, Psychological↗

PubMed1982

Developmental stages of Trypanosoma cruzi-like flagellates in Cavernicola pilosa.

The developmental stages of Trypanosoma cruzi ssp., found in the intestinal tract of Cavernicola pilosa, are described and measurements given for nine life stages. The frequencies of the various stages in foregut, midgut and hindgut of the triatomines are provided; parasites were rare in the foregut and metatrypomastigotes were seen only in the mid- and hindguts. All adult bugs examined harboured intestinal infections of T. cruzi-like flagellates, large clumps of amastigotes were frequently observed in the midgut. The faeces of C. pilosa, containing metacyclic trypomastigotes, did not produce patent parasitaemia when inoculated into mice. Inoculated mice were not protected against subsequent challenge infections with the highly virulent Tulahuen stock of T. c. cruzi. The blood of bats also failed to produce parasitaemia when inoculated into mice, nor were the mice protected against subsequent challenges with T. c. cruzi. Although the developmental stages described were very similar to those of T. c. cruzi it is presumed that they were stages of T. c. marinkellei because of their failure to infect mice and Rhodnius prolixus, and their failure to protect inoculated mice against challenge with T. c. cruzi.

Animals↗

PubMed1990

Effects of equilibration time, precooling and developmental stage on the survival of mouse embryos cryopreserved by vitrification.

Factorial experiments were carried out to examine the effects of equilibration time, precooling and developmental stage on the postthaw in vitro survival of vitrified mouse embryos. Eight-cell embryos, compacted morulae, or blastocysts were cryopreserved using vitrification Solution 1 (VS1; 10% glycerol + 20% propylene glycol), and vitrification Solution 2 (VS2; 25% glycerol + 25% propylene glycol) in phosphate buffered saline + 10% calf serum. Each embryo stage group was first equilibrated in VS1 for 5, 10 or 20 min and then exposed to either a precooled ( approximately 4 degrees C) or nonprecooled ( approximately 20 degrees C) VS2 in a 0.25-ml straw before they were plunged directly into liquid nitrogen. Results of this study showed an interaction between precooling, equilibration time and developmental stage which affect significantly post-thaw embryo survival (P< 0.05). High survival rates were obtained after 10 min equilibration in VS1 irrespective of the embryo developmental stage. Precooling of the VS2 significantly improved the survival mainly of blastocysts. However, eight-cell and morula-stage embryos also showed high survival rates when they were exposed to precooled VS2 after 5 min equilibration in VS1. It was further observed that morulae usually exhibit high survival rates, and vitrification conditions are more critical for early and advanced stage embryo development.

Journal Article↗

PubMedDate not supplied

[Laboratory investigation of the chemical disinfection against different developmental stages of the housefly (Musca domestica Linnaeus, 1758)].

Possibilities for disinfection of the developmental stages from the housefly (Musca domestica) were investigated under laboratory conditions. The developmental stages (eggs, larvae I, II, III, pupae and adults) were sprayed with solutions of disinfectants on the basis of p-chlorine-m-cresol and o-phenylphenol at different concentrations (0.025%-3%). The effectiveness of both disinfectants was established by determining the emergence rate of eggs and pupae and of the live evidence of larvae and adults. Transmission electron microscopic investigations of the cover of the eggs revealed the bactericidal effect of both disinfectants. These results show the necessity of extending its use also to noxious arthropods.

Animals↗

PubMed1990

Trypanosoma cruzi: differential expression and distribution of an 85-kDa polypeptide epitope by in vitro developmental stages.

The expression by Trypanosoma cruzi developmental stages of an 85-kDa polypeptide epitope defined by the 155D3 monoclonal antibody (mAb) has been investigated. Immunoprecipitation revealed the presence of an 85-kDa antigen in the NP-40 soluble extract of parasites freshly released from infected fibroblasts; this antigen was not found in epimastigote and Leishmania infantum promastigote. Indirect immunofluorescence revealed that the mAb 155D3 failed to react with trypomastigotes, whereas extracellular amastigotes were heavily stained. Positive organisms displayed either surface or polar fluorescence. Since the same mAb immunoprecipitated the 85-kDa antigen in both radioactive iodine- and methionine-labeled trypomastigote detergent soluble extracts, the reactive epitope is likely to be hidden in a cryptic site in trypomastigotes. An alternative explanation for the negative immunofluorescence on trypomastigotes and the positive immunoprecipitation is the presence, in the extracts, of a small population of parasites already expressing the 155D3 epitope. Immunoelectron microscopy revealed that the target epitope is heterogenously distributed among the populations of differentiating parasites. Two types of immunogold labeling were observed: (a) mAb revealed a high amount of reactive material associated with the periphery of the parasites and (b) a label was observed on the inner surface of peripheral vacuoles that might correspond to cross sections of inflated flagellar pockets and in association with vesicles which were released by the parasites. The surface expression of the epitope recognized by the 155D3 mAb was followed by fluorescence-activated cell-sorting analysis. The results showed that the epitope is increasingly accessible during trypomastigote differentiation in vitro. Taken together, these results suggest that the epitope reacting with the 155D3 mAb is heavily expressed on extracellular amastigotes after the transformation process and, thus, appears to be developmentally regulated.

Animals↗

PubMed1983

Schistosoma mansoni: complement activation in human and rodent sera by living parasites of various developmental stages.

Living Schistosoma mansoni of various developmental stages were studied with respect to their ability to activate the complement system in sera of humans, mice and rats. Immunofluorescence assays demonstrated that binding of human C3 occurred on fresh schistosomula as well as on schistosomula prepared from mouse lymph-nodes or lungs and on adult schistosomes. However, rodent C3 was deposited only on fresh schistosomula. Deposition of human C3 on the worms' surface required activation of the complement system. The alternative pathway was shown to be involved in deposition of human C3 on schistosomes of all ages, whereas activation of the classical pathway was demonstrable only with fresh schistosomula. Immunoelectrophoretic studies demonstrated a dose-dependent cleavage of human C3 and conversion of factor B by living adult schistosomes. The results demonstrate that the ability of living schistosomes to activate complement in vitro is dependent not only on their development stage but also on the species of the serum.

Animals↗

PubMed1994

[Surface ultrastructure of Parvatrema timondavidi (Digenea: Gymnophallidae) according to its developmental stages].

Surface ultrastructure of Parvatrema timondavidi developmental stages was studied using a scanning electron microscope. The metacercariae were collected from the marine clam. Tapes philippinarum, and juvenile and adult worms were recovered at 1, 2, 3 and 7 days after experimental infection of mice. The metacercariae had a large oral sucker and characteristic lateral projections. Around the lip of the oral sucker many type I and type II sensory papillae were observed, and type III papillae were located symmetrically on the medial side of the lateral projection. Numerous type I papillae were grouped around the genital pore. The tegumental spines were distributed over the worm surface except the lip of the suckers and genital pore. The 1-day old worm had a well-developed ventral sucker, with 6 type II sensory papillae on its outer surface and another 6 type I papillae on the inner side. Two small type I papillae were seen on the anterior side of the ventral sucker. The genital pore was small and opened separately from the ventral sucker and 15 type I papillae were grouped around it. The 2-, 3-, and 7-day worms revealed that as they grew to be adults, the spine tips became multipointed, the genital pore formed a genital atrium, and the cytoplasmic process became well differentiated. In 2- and 3-day worms 10 type II papillae encircling the lip of the oral sucker, and additional 4 papillae at the dorsal side of 4 dorsal type II papillae were a characteristic feature. The distribution pattern of sensory papillae around the oral sucker and genital pore, and 2 type I papillae on the anterior side of the ventral sucker, was so peculiar in P. timondavidi, that they seem to be useful keys for taxonomic differentiation from other gymnophallids.

Animals↗

PubMed2003

The influence of cooling rate, developmental stage, and the addition of sugar on the cryopreservation of larvae of the pearl oyster Pinctada fucata martensii.

This paper examines the effects of cooling rate, developmental stage, and the addition of sugar on the cryopreservation of the larvae of the pearl oyster, Pinctada fucata martensii. The survival rates of frozen-thawed trochophores was 43.1% at a cooling rate of 1.0 degrees C/min. The survival rate of frozen-thawed larvae increased with developmental stage, except for umbo stage larvae, and the late D-shaped larvae showed a survival rate as high as 91%. The addition of sugar (0.2M glucose or sucrose) improved the survival rate of larvae. These results indicate that the preferred cooling rate, developmental stage, and sugar for the cryopreservation of pearl oyster larvae are 1 degrees C/min, late D-shaped larvae and 0.2M glucose or sucrose.

Animals↗

PubMedDate not supplied

[Identification of developmental stages of wisdom teeth on orthopantomograms of adolescents and young adults as an aid for forensic-odontological age-estimations: predictive values for the chronological age of 18 years].

UNLABELLED: Dental findings are an important source of information regarding forensic-odontologic determination of identity and age. A main part of dental age assessment is the determination of the wisdom teeth' development. The aim of this study was to answer the question whether the development of wisdom teeth can give information for the task of individual age estimation. Thereby, the investigation could contribute to age estimation efforts that are carried out on persons with an unknown age and where it is of high importance to know as exactly as possible the age of a person, e.g. the age of 18 years or older, for determining the punishment for a criminal offence. MATERIAL AND METHODS: The orthopantomograms of 1053 outpatients were evaluated. The patients were aged 14 to 24 years. The developmental stages of the wisdom teeth were determined according to Demirjian. The data were calculated using statistical tools, like descriptive and inferential statistics in order to provide predictive values for the age to be above or below 18 years. RESULTS: The correlation between the developmental stages of wisdom teeth and the chronological age was high in general. Some values allowed the prediction of an age above 18 years with a probability of more than 70% to 80%, in some instances even more than 90%. The most appropriate developmental stage to determine the age of 18 years was A 1/2 (completed root development, apex open). The positive predictive value of this finding was 94%. DISCUSSION: This study provides for the first time predictive values for the estimation whether or not a person is 18 years of age, based on the evaluation of developmental stages of wisdom teeth on orthopantomograms only. These results should be compared to data from other populations gained by the same method.

Adolescent↗

PubMedDate not supplied

Isolation and metabolism of glycogen and poly-betahydroxybutyrate in Nocardia asteroides at different developmental stages.

Sudanophilic and iodine-staining cytoplasmic granules were isolated at various developmental stages during growth of Nocardia asteroides (strain 55) and identified as poly-beta-hydroxybutyrate (PHB) and glycogen granules, respectively. During growth in nutrient broth containing 1% glucose, maximal accumulation of PHB and glycogen granules, up to 10 and 20% respectively, of its dry-weight was obtained in the filamentous cells at 16 h just prior to the onset of cell fragmentation during the stationary phase. The decrease of the cytoplasmic granules was concomitant with fragmentation of the cells to rod-like and spherical cells, suggesting that the polymers may serve as carbon and energy source during morphogenesis. Both granules were detected in the three cell-forms. At higher concentrations of glucose (4%) more glycogen granules (9 times) accumulated than PHB (4 times) and glycogen hydrolysis was also faster than that of PHB, suggesting preferences of glycogen over PHB as energy and carbon source under this growth condition. Growth and biosynthesis of granules were significantly reduced by very high glucose concentration (10%) and the usual pleomorphic developmental stages were reduced to a dimorphic life cycle. Thus, biosynthesis of both granules and morphogenesis are under catabolite repression. Both polymers were also found in N. brasiliensis and N. otitidis-caviarum, indicating that cytoplasmic accumulation of multiple granules is common in the genus.

Cytoplasmic Granules↗