Spelling suggestions: "subject:"life stages"" "subject:"wife stages""
1 |
An integrated ecotoxicological assessment of the engineered nanoparticles, C₆₀ fullerenes, in different life stages of marine mussels, Mytilus edulisAl-Subiai, Sherain Naser January 2011 (has links)
Studies were undertaken to determine ecotoxicological effects of model manufactured or engineered nanoparticles (ENPs), either alone or in combination with a representative polycyclic aromatic hydrocarbon (i.e. PAHs: fluoranthene) at different levels of biological organisation (viz. biochemical, histological and behavioural levels) in a sentinel, widely distributed marine invertebrate species, Mytilus edulis. With the current and predicted levels of pollution in the marine and coastal environment, there is an urgent need to establish the potential effects of persistent and emerging contaminants which includes ENPs and PAHs, to protect human and environmental health. In this study, initially, it was aimed to optimise the induction of biotransformation enzyme P-450 as a robust biochemical tool and good progress (chapter 3) was made to standardise P-450 in mussel. Due to certain technical and logistic limitations however we could not apply measurement of P-450 as potential biochemical biomarkers in this species. The possibility of using glutathione levels instead in the cell-free component of haemolymph samples as an indicator of oxidative stress, in an analogous way to that used in mammals was evaluated (chapter 4). The evidence suggested that cell-free haemolymph samples collected from adductor muscle of Mytilus edulis may be significantly contaminated with intracellular contents of myocytes of this organ (i.e. adductor muscle) and adductor muscle tissue is more generally useful to determine glutathione system responses. The validation study of different assays using copper as a relevant environmental contaminant (chapter 5) suggested the existence of clear relationships between genotoxic (as determined by induction of DNA strand breaks using the Comet assay) and higher level effects. The results further suggested the feasibility of adoption of an integrated approach and robustness of selected biomarkers to evaluate short and long-term toxic effects of pollutants. A multiple biomarker approach was then used to determine the potential interactive effect of C60 fullerenes in combination with fluoranthene. Where appropriate analytical tools (i.e. ICP-MS, GC-MS) were used to determine the levels of contaminant exposure and characterise the properties of the ENPs. The combined exposure of fluoranthene and C60 fullerenes produced enhanced biological damage at approximately at an- “additive” rather than synergistic level, which appeared to be as a result of oxidative stress (chapter 6). The final experiments were carried out in both the early and adult life stages to test the potential toxicity resulting from photochemical transformation of C60 fullerenes in Mytilus edulis (chapter 7). In general, the results showed, for the first time, genotoxic and developmental impact of the photochemically transformed C60 fullerenes at different life stages of marine mussel. Further research is required to identify the degraded products of C60 fullerenes and to understand the mechanism by which fresh and aged C60 fullerenes induces biological responses including oxidative stress and affect ecologically relevant aquatic organisms at different life stages. The thesis has taken the opportunity to discuss (chapter 8) the importance of applications of biological responses in hazard and risk assessment posed by anthropogenic chemicals in a broader context.
|
2 |
Metabolic Responses to Crude Oil during Very Early Development in the Zebrafish (Danio rerio)Vazquez Roman, Karem Nathalie 08 1900 (has links)
The present study sought to determine some morphological and physiological critical windows during very early development in zebrafish exposed to crude oil. I hypothesized that exposed zebrafish would present a decrease in survival rate and body mass, and an increase in routine oxygen consumption (ṀO2), and critical oxygen tension (PCrit). To test these hypotheses, zebrafish were acutely exposed (24 h) during different days of development (1 to 6 days post-fertilization, dpf) to different concentrations of high-energy water-accommodated fractions (HEWAFs). The endpoints of survival, body mass, routine oxygen consumption, and critical oxygen partial pressure were measured at 7 dpf. Survival rate decreased based on the exposure concentration but not as a function of the day of crude oil exposure. No significant effects were found in PCrit. Body mass was reduced by the different concentrations of HEWAF, with the size of the effect varying with exposure day, with the effect strongest on when exposure occurred at 2 and 3 dpf. Oxygen consumption (ṀO2) differed significantly depending upon the day of exposure in fish exposed to crude oil. Specifically, HEWAF exposure significantly increased ṀO2 in larvae exposed at 3 dpf (9.081 µmol O2/g/h, ±0.559) versus 2 dpf (6.068 µmol O2/g/h, ±0.652) and 6 dpf (6.485 µmol O2/g/h, ±0.609). Overall, the main effects on body mass and ṀO2 occurred at crude oil exposures during 3 dpf. The presence of a critical window in fish is proposed at this developmental time, which coincides with the hatching period.
|
3 |
Emerging Adulthood as a Critical Stage in the Life CourseWood, David L., Crapnell, T., Lau, L., Bennett, A., Lotstein, D., Ferris, M., Kuo, Alice 21 November 2017 (has links)
Book Summary:
This handbook synthesizes and analyzes the growing knowledge base on life course health development (LCHD) from the prenatal period through emerging adulthood, with implications for clinical practice and public health. It presents LCHD as an innovative field with a sound theoretical framework for understanding wellness and disease from a lifespan perspective, replacing previous medical, biopsychosocial, and early genomic models of health. Interdisciplinary chapters discuss major health concerns (diabetes, obesity), important less-studied conditions (hearing, kidney health), and large-scale issues (nutrition, adversity) from a lifespan viewpoint. In addition, chapters address methodological approaches and challenges by analyzing existing measures, studies, and surveys. The book concludes with the editors’ research agenda that proposes priorities for future LCHD research and its application to health care practice and health policy.
Topics featured in the Handbook include:
The prenatal period and its effect on child obesity and metabolic outcomes. Pregnancy complications and their effect on women’s cardiovascular health. A multi-level approach for obesity prevention in children. Application of the LCHD framework to autism spectrum disorder. Socioeconomic disadvantage and its influence on health development across the lifespan. The importance of nutrition to optimal health development across the lifespan.
The Handbook of Life Course Health Development is a must-have resource for researchers, clinicians/professionals, and graduate students in developmental psychology/science; maternal and child health; social work; health economics; educational policy and politics; and medical law as well as many interrelated subdisciplines in psychology, medicine, public health, mental health, education, social welfare, economics, sociology, and law.
|
4 |
Endocrine Disruption of Levonorgestrel in Early-life Stages of Fathead Minnows, Pimephales PromelasOverturf, Matthew D. 08 1900 (has links)
Pharmaceuticals have routinely been detected in the environment resulting in a growing concern about whether these drugs could elicit effects on aquatic organisms. The concerns are centered on the highly conserved nature of mammalian therapeutic targets in fish. These pharmaceuticals are found at very low levels in the environment, which can result in sub-lethal effects in aquatic organisms. Therefore, 28 d early-life stage studies were conducted on six pharmaceuticals to assess their impacts on survival and growth fathead minnow larvae. Two pharmaceuticals tested, carbamazepine and fenofibrate, resulted in no alterations to survival and growth. However, amiodarone, clozapine, dexamethasone, and levonorgestrel (LNG) reduced survival at concentrations tested with LNG being the most potent at 462 ng/L. Survival was increased with amiodarone and clozapine; however LNG significantly decreased growth at 86 ng/L. Therefore, the most potent pharmaceutical tested was the synthetic progestin LNG with survival and growth impacts at concentrations less than 1 μg/L. Further analysis was conducted by measuring specific endocrine related mRNA transcript profiles in FHM larvae following the 28 d ELS exposure to LNG. Transcripts of 3β-HSD, 20β-HSD, and FSH were significantly down-regulated following 28 d exposure to both 16.3 and 86.9 ng/L LNG. Also, CYP19a expression was significantly down-regulated at 86.9 and 2392 ng/L LNG. Subsequently, a second study examined time periods that may be most sensitive (e.g., windows of sensitivity) for FHM larvae exposed to LNG. Larvae were exposed to a single concentration of LNG (i.e. LOECgrowth of 86.2 ng/L as determined in the 28 d ELS study) for different time periods starting with fertilized egg through 28 dph. Growth and mRNA expression of the four differentially expressed transcripts from the first study were measured. Regardless of the duration of exposure, LNG significantly decreased growth in fathead minnow larvae at day 28. For both 20β-HSD and CYP19a, mRNA expression was decreased following exposure to LNG; however, these transcripts returned to baseline levels after removal of LNG. 3β-HSD and FSH showed similar trends after exposure to LNG with 7-14 d and 14-28 d exposures exhibiting a decrease in expression; however, FSH expression returned to baseline once removed for LNG exposure. Based on these data, 3β-HSD was the only transcript to remain down regulated after LNG exposure. Together these data suggest LNG can negatively impact FHM larval survival and growth, with significant alterations in endocrine related responses. However, these changes in endocrine related responses may not directly correlate to the changes in growth demonstrated with LNG exposure to fathead minnows. Therefore, additional research is warranted to ascertain additional mechanisms, either endocrine related or non-endocrine functions, related to changes in growth of larval fathead minnows.
|
5 |
Amino acid metabolism and requirement in teleost during their early life stages and implications in fish formulated dietsZhang, Yongfang 08 January 2008 (has links)
No description available.
|
6 |
Men’s reflections on their body image at different life stages: A thematic analysis of interview accounts from middle-aged menMalik, Mohammed, Grogan, S., Cole, J., Gough, B. 26 August 2019 (has links)
Yes / This study investigates how men’s body image develops over time. 14 men aged between 45 and 67 years completed in-depth interviews where they discussed their body image since childhood, prompted in some cases by photographs of themselves at different ages that they brought to the interviews. Transcripts were analysed using inductive thematic analysis. From the participants’ accounts it was evident that body concerns did not steadily improve or worsen, but waxed and waned over time. Results are discussed in relation to understanding changing body concerns in men’s lives, and the implications of these for future research and practice.
|
7 |
Gender Differences and Similarities in the Work-family Interface: The Importance of Considering Family Life StagesMartinengo, Giuseppe 26 October 2007 (has links) (PDF)
This study focuses on the importance of considering the interaction between gender and family life stages to properly understand gender similarities and differences in the work and family interface. Data for this study come from the IBM 2004 Global Work and Life Issues Survey representing 79 countries (N=41,813). This study is a first step toward a better understanding of similarities and differences among male and female workers across the life course and it shows that work, family and life outcomes are similar across groups, independent of life stages or gender. Six family life stage groups were created: no children and workers age 35 or less, transition to parenthood, preschool children, elementary children, teenagers, and empty nest (workers age 50 years or older and no children dependent). The findings indicate that gender differences increase when young children are present. Parenthood creates or maintains a more gendered family and work life. A key characteristic of the first stage is that gender differences are smaller than in later stages. In the transition to parenthood stage, gender differences increase substantially. For example, the difference in work hours increases four times from the previous life stage and males experience substantially more work-to-family conflict than females. The preschool stage is the stage in which gender differences in work hours and work-to-family conflict reach their highest point. In the elementary children stage, gender differences in work hours and work-to-family conflict decrease to a level very similar to the transition to parenthood stage. In the teenager children stage, differences in work-to-family conflict decrease to levels similar to the first life stage and differences in access-use of work-family programs decrease to levels similar to the transition to parenthood stages. Finally, in the empty nest stage gender differences are small and some are unique to this stage. Future research could benefit from exploring how the fit of the model may change with the addition of other important work-family variables that were not adequately measured in this study because the data were collected in a corporate setting. Employers could benefit from applying these research findings to the development of work policies and programs attentive to shifts in work-family linkages over the life course.
|
8 |
Habitat utilisation of burnet moths (<em>Zygaena</em> spp.) in southern Sweden: a multi-stage and multi-scale perspectiveSarin, Camilla January 2009 (has links)
<p>Three species of burnet moths (<em>Zygaena</em> <em>filipendulae</em>,<em> Z</em>. <em>lonicerae</em> and <em>Z</em>. <em>viciae</em>) were studied on the Baltic island Öland, Sweden, in order to reveal the habitat requirements of different life stages. Larvae were found among a higher cover of their most important host plant, <em>Lotus corniculatus</em>, <em>Trifolium medium</em>/<em>pratense </em>or<em> Vicia </em>spp., than were pupae or imagines, and were also observed on plants larger than randomly examined plants. Imagines actively selected nectar plants of <em>Centaurea </em>and <em>Cirsium</em>, growing in sunny conditions, but other red and violet Asteraceae flowers were also favoured. Pupae of <em>Z</em>.<em> filipendulae</em> appeared in taller vegetation than larvae and imagines, probably because the cocoons are spun high on stems of grasses and other plants. The chance of finding such suitable substrates rises with increasing vegetation height. A large scale analysis of occupancy patterns was also made, evaluating the relationship between burnet presence or absence and the area of meadows and pastures within 10 x 10 km grid cells in southern Sweden. All three species showed a positive relationship with increasing area of semi-natural grassland. Thresholds for the amount of habitat, below which the likelihood of occurrence declined more rapidly, could be distinguished around a 40-50 % probability of occurrence. Conservational work should aim at preserving and restoring open and sunny areas, rich in the respective host plants and nectar sources, but vegetation management must be executed with great care or late in the season to not harm unhatched pupae and to maintain substrates suitable for <em>Z</em>. <em>filipendulae</em> pupation.</p>
|
9 |
Habitat utilisation of burnet moths (Zygaena spp.) in southern Sweden: a multi-stage and multi-scale perspectiveSarin, Camilla January 2009 (has links)
Three species of burnet moths (Zygaena filipendulae, Z. lonicerae and Z. viciae) were studied on the Baltic island Öland, Sweden, in order to reveal the habitat requirements of different life stages. Larvae were found among a higher cover of their most important host plant, Lotus corniculatus, Trifolium medium/pratense or Vicia spp., than were pupae or imagines, and were also observed on plants larger than randomly examined plants. Imagines actively selected nectar plants of Centaurea and Cirsium, growing in sunny conditions, but other red and violet Asteraceae flowers were also favoured. Pupae of Z. filipendulae appeared in taller vegetation than larvae and imagines, probably because the cocoons are spun high on stems of grasses and other plants. The chance of finding such suitable substrates rises with increasing vegetation height. A large scale analysis of occupancy patterns was also made, evaluating the relationship between burnet presence or absence and the area of meadows and pastures within 10 x 10 km grid cells in southern Sweden. All three species showed a positive relationship with increasing area of semi-natural grassland. Thresholds for the amount of habitat, below which the likelihood of occurrence declined more rapidly, could be distinguished around a 40-50 % probability of occurrence. Conservational work should aim at preserving and restoring open and sunny areas, rich in the respective host plants and nectar sources, but vegetation management must be executed with great care or late in the season to not harm unhatched pupae and to maintain substrates suitable for Z. filipendulae pupation.
|
10 |
Habitat selection and oviposition of the endangered butterfly Scolitantides orion in Sweden.Jansson, Camilla January 2013 (has links)
Detailed knowledge about the habitat requirements of butterflies is vital for successful conservation. The aim of the present study was to examine the habitat requirements of the endangered butterfly Scolitantides orion on 15 sites in Östergötland, Sweden. The requirements of adults and ovipositing females were studied with regard to several environmental variables measured at three scales; small, transect and large scale. The probability of finding adults increased with decreasing tree cover at the small scale, and adult numbers increased with the proportion of bare rock at the large scale. In contrast, ovipositing females mainly responded to the small scale. The main finding was that females oviposited in areas with higher tree cover (< 70 %) than that preferred by dwelling adults (< 20 %). However, there was a greater probability of finding eggs when tree cover was less than 50 %. Furthermore, egg numbers on host plants increased with the number of leaves on the stem and with the proportion of surrounding bare rock or bare ground. At the transect scale, females oviposited in areas with a higher density of host plants. To conclude, S. orion predominately inhabits open areas with warm microclimatic conditions for dwelling and oviposition. To conserve this species, suitable areas containing nectar plants and high densities of host plants with large leaf numbers and surrounded by large proportions of bare rock or bare ground, should be preserved. The areas should be maintained by selective clearing at regular intervals to uphold canopy openness and heterogeneity.
|
Page generated in 0.0552 seconds