The Experts below are selected from a list of 82713 Experts worldwide ranked by ideXlab platform

Hans A Hofmann - One of the best experts on this subject based on the ideXlab platform.

  • social status predicts how sex steroid receptors regulate complex behavior across levels of Biological Organization
    Endocrinology, 2012
    Co-Authors: Lauren A Oconnell, Hans A Hofmann
    Abstract:

    Social status strongly affects behavior and physiology, in part mediated by gonadal hormones, although how each sex steroid acts across levels of Biological Organization is not well understood. We examine the role of sex steroids in modulating social behavior in dominant (DOM) and subordinate (SUB) males of a highly social fish, Astatotilapia burtoni. We first used agonists and antagonists to each sex steroid receptor and found that androgens and progestins modulate courtship behavior only in DOM, whereas estrogens modulate aggressive behavior independent of social status. We then examined the hormonal and physiological responses to sex steroid receptor antagonist treatment and uncovered substantial changes in circulating steroid hormone levels and gonad size only in SUB, not in DOM. Consistent with status-based physiological sensitivities to drug manipulation, we found that neuropeptide and steroid receptor gene expression in the preoptic area was sensitive only in SUB. However, when we compared the transcriptomes of males that received either vehicle or an estrogen receptor antagonist, 8.25% of all genes examined changed expression in DOM in comparison with only 0.56% in SUB. Finally, we integrate behavior, physiology, and brain gene expression to infer functional modules that underlie steroid receptor regulation of behavior. Our work suggests that environmentally induced changes at one level of Biological Organization do not simply affect changes of similar magnitude at other levels, but that instead very few key pathways likely serve as conduits for executing plastic responses across multiple levels.

  • social status predicts how sex steroid receptors regulate complex behavior across levels of Biological Organization
    Endocrinology, 2012
    Co-Authors: Lauren A Oconnell, Hans A Hofmann
    Abstract:

    Social status strongly affects behavior and physiology, in part mediated by gonadal hormones, although how each sex steroid acts across levels of Biological Organization is not well understood. We examine the role of sex steroids in modulating social behavior in dominant (DOM) and subordinate (SUB) males of a highly social fish, Astatotilapia burtoni. We first used agonists and antagonists to each sex steroid receptor and found that androgens and progestins modulate courtship behavior only in DOM, whereas estrogens modulate aggressive behavior independent of social status. We then examined the hormonal and physiological responses to sex steroid receptor antagonist treatment and uncovered substantial changes in circulating steroid hormone levels and gonad size only in SUB, not in DOM. Consistent with status-based physiological sensitivities to drug manipulation, we found that neuropeptide and steroid receptor gene expression in the preoptic area was sensitive only in SUB. However, when we compared the tran...

  • the neuroendocrine action potential winner of the 2008 frank beach award in behavioral neuroendocrinology
    Hormones and Behavior, 2010
    Co-Authors: Hans A Hofmann
    Abstract:

    article i nfo Animals are remarkably well equipped to respond to changes in their environment across different time scales and levels of Biological Organization. Here, I introduce a novel perspective that incorporates the three main processes the nervous system uses to integrate and process information: electrophysiological, genomic, and neuroendocrine action potentials. After discussing several examples of neuroendocrine action potentials, I lay out the commonalities of these temporally organized responses and how they might be interrelated with electrophysiological activity and genomic responses. This framework provides a novel outlook on longstanding questions in behavioral neuroendocrinology and suggests exciting new avenues for further research that will integrate across disciplines and levels of Biological Organization.

Lauren A Oconnell - One of the best experts on this subject based on the ideXlab platform.

  • social status predicts how sex steroid receptors regulate complex behavior across levels of Biological Organization
    Endocrinology, 2012
    Co-Authors: Lauren A Oconnell, Hans A Hofmann
    Abstract:

    Social status strongly affects behavior and physiology, in part mediated by gonadal hormones, although how each sex steroid acts across levels of Biological Organization is not well understood. We examine the role of sex steroids in modulating social behavior in dominant (DOM) and subordinate (SUB) males of a highly social fish, Astatotilapia burtoni. We first used agonists and antagonists to each sex steroid receptor and found that androgens and progestins modulate courtship behavior only in DOM, whereas estrogens modulate aggressive behavior independent of social status. We then examined the hormonal and physiological responses to sex steroid receptor antagonist treatment and uncovered substantial changes in circulating steroid hormone levels and gonad size only in SUB, not in DOM. Consistent with status-based physiological sensitivities to drug manipulation, we found that neuropeptide and steroid receptor gene expression in the preoptic area was sensitive only in SUB. However, when we compared the tran...

  • social status predicts how sex steroid receptors regulate complex behavior across levels of Biological Organization
    Endocrinology, 2012
    Co-Authors: Lauren A Oconnell, Hans A Hofmann
    Abstract:

    Social status strongly affects behavior and physiology, in part mediated by gonadal hormones, although how each sex steroid acts across levels of Biological Organization is not well understood. We examine the role of sex steroids in modulating social behavior in dominant (DOM) and subordinate (SUB) males of a highly social fish, Astatotilapia burtoni. We first used agonists and antagonists to each sex steroid receptor and found that androgens and progestins modulate courtship behavior only in DOM, whereas estrogens modulate aggressive behavior independent of social status. We then examined the hormonal and physiological responses to sex steroid receptor antagonist treatment and uncovered substantial changes in circulating steroid hormone levels and gonad size only in SUB, not in DOM. Consistent with status-based physiological sensitivities to drug manipulation, we found that neuropeptide and steroid receptor gene expression in the preoptic area was sensitive only in SUB. However, when we compared the transcriptomes of males that received either vehicle or an estrogen receptor antagonist, 8.25% of all genes examined changed expression in DOM in comparison with only 0.56% in SUB. Finally, we integrate behavior, physiology, and brain gene expression to infer functional modules that underlie steroid receptor regulation of behavior. Our work suggests that environmentally induced changes at one level of Biological Organization do not simply affect changes of similar magnitude at other levels, but that instead very few key pathways likely serve as conduits for executing plastic responses across multiple levels.

Tollefsen Knut-erik - One of the best experts on this subject based on the ideXlab platform.

  • Integrative assessment of low-dose gamma radiation effects on Daphnia magna reproduction: Toxicity pathway assembly and AOP development
    'Elsevier BV', 2020
    Co-Authors: Song You, Li Xie, Lee Yeonkyeong, Brede, Dag Anders, Lyne Fern, Kassaye, Yetneberk Ayalew, Thaulow Jens, Caldwell, Gary S., Salbu Brit, Tollefsen Knut-erik
    Abstract:

    High energy gamma radiation is potentially hazardous to organisms, including aquatic invertebrates. Although extensively studied in a number of invertebrate species, knowledge on effects induced by gamma radiation is to a large extent limited to the induction of oxidative stress and DNA damage at the molecular/cellular level, or survival, growth and reproduction at the organismal level. As the knowledge of causal relationships between effects occurring at different levels of Biological Organization is scarce, the ability to provide mechanistic explanation for observed adverse effects is limited, and thus development of Adverse Outcome Pathways (AOPs) and larger scale implementation into next generation hazard and risk predictions is restricted. The present study was therefore conducted to assess the effects of high-energy gamma radiation from cobalt-60 across multiple levels of Biological Organization (i.e., molecular, cellular, tissue, organ and individual) and characterize the major toxicity pathways leading to impaired reproduction in the model freshwater crustacean Daphnia magna (water flea). Following gamma exposure, a number of bioassays were integrated to measure relevant toxicological endpoints such as gene expression, reactive oxygen species (ROS), lipid peroxidation (LPO), neutral lipid storage, adenosine triphosphate (ATP) content, apoptosis, ovary histology and reproduction. A non-monotonic pattern was consistently observed across the levels of Biological Organization, albeit with some variation at the lower end of the dose-rate scale, indicating a complex response to radiation doses. By integrating results from different bioassays, a novel pathway network describing the key toxicity pathways involved in the reproductive effects of gamma radiation were proposed, such as DNA damage-oocyte apoptosis pathway, LPO-ATP depletion pathway, calcium influx-endocrine disruption pathway and DNA hypermethylation pathway. Three novel AOPs were proposed for oxidative stressor-mediated excessive ROS formation leading to reproductive effect, and thus introducing the world's first AOPs for non-chemical stressors in aquatic invertebrates.publishedVersio

  • Integrative assessment of low-dose gamma radiation effects on Daphnia magna reproduction: Toxicity pathway assembly and AOP development
    'Elsevier BV', 2020
    Co-Authors: Song You, Li Xie, Lee Yeonkyeong, Brede, Dag Anders, Lyne Fern, Kassaye, Yetneberk Ayalew, Thaulow Jens, Caldwell, Gary S., Salbu Brit, Tollefsen Knut-erik
    Abstract:

    High energy gamma radiation is potentially hazardous to organisms, including aquatic invertebrates. Although extensively studied in a number of invertebrate species, knowledge on effects induced by gamma radiation is to a large extent limited to the induction of oxidative stress and DNA damage at the molecular/cellular level, or survival, growth and reproduction at the organismal level. As the knowledge of causal relationships between effects occurring at different levels of Biological Organization is scarce, the ability to provide mechanistic explanation for observed adverse effects is limited, and thus development of Adverse Outcome Pathways (AOPs) and larger scale implementation into next generation hazard and risk predictions is restricted. The present study was therefore conducted to assess the effects of high-energy gamma radiation from cobalt-60 across multiple levels of Biological Organization (i.e., molecular, cellular, tissue, organ and individual) and characterize the major toxicity pathways leading to impaired reproduction in the model freshwater crustacean Daphnia magna (water flea). Following gamma exposure, a number of bioassays were integrated to measure relevant toxicological endpoints such as gene expression, reactive oxygen species (ROS), lipid peroxidation (LPO), neutral lipid storage, adenosine triphosphate (ATP) content, apoptosis, ovary histology and reproduction. A non-monotonic pattern was consistently observed across the levels of Biological Organization, albeit with some variation at the lower end of the dose-rate scale, indicating a complex response to radiation doses. By integrating results from different bioassays, a novel pathway network describing the key toxicity pathways involved in the reproductive effects of gamma radiation were proposed, such as DNA damage-oocyte apoptosis pathway, LPO-ATP depletion pathway, calcium influx-endocrine disruption pathway and DNA hypermethylation pathway. Three novel AOPs were proposed for oxidative stressor-mediated excessive ROS formation leading to reproductive effect, and thus introducing the world's first AOPs for non-chemical stressors in aquatic invertebrates

  • Effects of artificial ultraviolet B radiation on the macrophyte Lemna minor: a conceptual study for toxicity pathway characterization
    2020
    Co-Authors: Li Xie, Song You, Solhaug, Knut Asbjørn, Johnsen Bjørn, Olsen, Jorunn Elisabeth, Tollefsen Knut-erik
    Abstract:

    Macrophytes inhabit waterways around the world and are used in hydroponics or aquaponics for different purposes such as feed and wastewater treatment and are thus exposed to elevated levels of UVB from natural and artificial sources. Although high UVB levels are harmful to macrophytes, mechanistic understanding of irradiance-dependent effects and associated modes of action in non-UVB acclimated plants still remains low. The present study was conducted to characterise the irradiance-dependent mechanisms of UVB leading to growth inhibition in Lemna minor as an aquatic macrophyte model. The L. minor were continuously exposed to UVB (0.008–4.2 W m−2) and constant UVA (4 W m−2) and photosynthetically active radiation, PAR (80 µmol m−2 s−1) for 7 days. A suite of bioassays was deployed to assess effects on oxidative stress, photosynthesis, DNA damage, and transcription of antioxidant biosynthesis, DNA repair, programmed cell death, pigment metabolism and respiration. The results showed that UVB triggered both irradiance-dependent and target-specific effects at multiple levels of Biological Organization, whereas exposure to UVA alone did not cause any effects. Inhibition of photosystem II and induction of carotenoids were observed at 0.23 W m−2, whereas growth inhibition, excessive reactive oxygen species, lipid peroxidation, cyclobutane pyrimidine dimer formation, mitochondrial membrane potential reduction and chlorophyll depletion were observed at 0.5–1 W m−2. Relationships between responses at different levels of Biological Organization were used to establish a putative network of toxicity pathways to improve our understanding of UVB effects in aquatic macrophytes under continuous UVB exposures. Additional studies under natural illuminations were proposed to assess whether these putative toxicity pathways may also be relevant for more ecologically relevant exposure scenarios

  • Effects of artificial ultraviolet B radiation on the macrophyte Lemna minor: a conceptual study for toxicity pathway characterization
    'Springer Science and Business Media LLC', 2020
    Co-Authors: Li Xie, Song You, Solhaug, Knut Asbjørn, Johnsen Bjørn, Olsen, Jorunn Elisabeth, Tollefsen Knut-erik
    Abstract:

    Macrophytes inhabit waterways around the world and are used in hydroponics or aquaponics for different purposes such as feed and wastewater treatment and are thus exposed to elevated levels of UVB from natural and artificial sources. Although high UVB levels are harmful to macrophytes, mechanistic understanding of irradiance-dependent effects and associated modes of action in non-UVB acclimated plants still remains low. The present study was conducted to characterise the irradiance-dependent mechanisms of UVB leading to growth inhibition in Lemna minor as an aquatic macrophyte model. The L. minor were continuously exposed to UVB (0.008–4.2 W m−2) and constant UVA (4 W m−2) and photosynthetically active radiation, PAR (80 µmol m−2 s−1) for 7 days. A suite of bioassays was deployed to assess effects on oxidative stress, photosynthesis, DNA damage, and transcription of antioxidant biosynthesis, DNA repair, programmed cell death, pigment metabolism and respiration. The results showed that UVB triggered both irradiance-dependent and target-specific effects at multiple levels of Biological Organization, whereas exposure to UVA alone did not cause any effects. Inhibition of photosystem II and induction of carotenoids were observed at 0.23 W m−2, whereas growth inhibition, excessive reactive oxygen species, lipid peroxidation, cyclobutane pyrimidine dimer formation, mitochondrial membrane potential reduction and chlorophyll depletion were observed at 0.5–1 W m−2. Relationships between responses at different levels of Biological Organization were used to establish a putative network of toxicity pathways to improve our understanding of UVB effects in aquatic macrophytes under continuous UVB exposures. Additional studies under natural illuminations were proposed to assess whether these putative toxicity pathways may also be relevant for more ecologically relevant exposure scenarios.publishedVersio

Rosario Planello - One of the best experts on this subject based on the ideXlab platform.

  • exposure to heavy metal contaminated sediments disrupts gene expression lipid profile and life history traits in the midge chironomus riparius
    Water Research, 2020
    Co-Authors: Helene Arambourou, Lola Llorente, Inigo Morenoocio, Oscar Herrero, Carlos Barata, Inmaculada Fuertes, Nicolas Delorme, Leire Mendezfernandez, Rosario Planello
    Abstract:

    Abstract Despite the concern about anthropogenic heavy metal accumulation, there remain few multi-level ecotoxicological studies to evaluate their effects in fluvial ecosystems. The toxicity of field-collected sediments exhibiting a gradient of heavy metal contamination (Cd, Pb, and Zn) was assessed in Chironomus riparius. For this purpose, larvae were exposed throughout their entire life cycle to these sediments, and toxic effects were measured at different levels of Biological Organization, from the molecular (lipidomic analysis and transcriptional profile) to the whole organism response (respiration rate, shape markers, and emergence rate). Alterations in the activity of relevant genes, as well as an increase of storage lipids and decrease in membrane fluidity, were detected in larvae exposed to the most contaminated sediments. Moreover, reduced larval and adult mass, decrease of larval respiration rate, and delayed emergence were observed, along with increased mentum and mandible size in larvae and decreased wing loading in adults. This study points out the deleterious effects of heavy metal exposure at various levels of Biological Organization and provides some clues regarding the mode of toxic action. This integrative approach provides new insights into the multi-level effects on aquatic insects exposed to heavy metal mixtures in field sediments, providing useful tools for ecological risk assessment in freshwater ecosystems.

Song You - One of the best experts on this subject based on the ideXlab platform.

  • Integrative assessment of low-dose gamma radiation effects on Daphnia magna reproduction: Toxicity pathway assembly and AOP development
    'Elsevier BV', 2020
    Co-Authors: Song You, Li Xie, Lee Yeonkyeong, Brede, Dag Anders, Lyne Fern, Kassaye, Yetneberk Ayalew, Thaulow Jens, Caldwell, Gary S., Salbu Brit, Tollefsen Knut-erik
    Abstract:

    High energy gamma radiation is potentially hazardous to organisms, including aquatic invertebrates. Although extensively studied in a number of invertebrate species, knowledge on effects induced by gamma radiation is to a large extent limited to the induction of oxidative stress and DNA damage at the molecular/cellular level, or survival, growth and reproduction at the organismal level. As the knowledge of causal relationships between effects occurring at different levels of Biological Organization is scarce, the ability to provide mechanistic explanation for observed adverse effects is limited, and thus development of Adverse Outcome Pathways (AOPs) and larger scale implementation into next generation hazard and risk predictions is restricted. The present study was therefore conducted to assess the effects of high-energy gamma radiation from cobalt-60 across multiple levels of Biological Organization (i.e., molecular, cellular, tissue, organ and individual) and characterize the major toxicity pathways leading to impaired reproduction in the model freshwater crustacean Daphnia magna (water flea). Following gamma exposure, a number of bioassays were integrated to measure relevant toxicological endpoints such as gene expression, reactive oxygen species (ROS), lipid peroxidation (LPO), neutral lipid storage, adenosine triphosphate (ATP) content, apoptosis, ovary histology and reproduction. A non-monotonic pattern was consistently observed across the levels of Biological Organization, albeit with some variation at the lower end of the dose-rate scale, indicating a complex response to radiation doses. By integrating results from different bioassays, a novel pathway network describing the key toxicity pathways involved in the reproductive effects of gamma radiation were proposed, such as DNA damage-oocyte apoptosis pathway, LPO-ATP depletion pathway, calcium influx-endocrine disruption pathway and DNA hypermethylation pathway. Three novel AOPs were proposed for oxidative stressor-mediated excessive ROS formation leading to reproductive effect, and thus introducing the world's first AOPs for non-chemical stressors in aquatic invertebrates.publishedVersio

  • Integrative assessment of low-dose gamma radiation effects on Daphnia magna reproduction: Toxicity pathway assembly and AOP development
    'Elsevier BV', 2020
    Co-Authors: Song You, Li Xie, Lee Yeonkyeong, Brede, Dag Anders, Lyne Fern, Kassaye, Yetneberk Ayalew, Thaulow Jens, Caldwell, Gary S., Salbu Brit, Tollefsen Knut-erik
    Abstract:

    High energy gamma radiation is potentially hazardous to organisms, including aquatic invertebrates. Although extensively studied in a number of invertebrate species, knowledge on effects induced by gamma radiation is to a large extent limited to the induction of oxidative stress and DNA damage at the molecular/cellular level, or survival, growth and reproduction at the organismal level. As the knowledge of causal relationships between effects occurring at different levels of Biological Organization is scarce, the ability to provide mechanistic explanation for observed adverse effects is limited, and thus development of Adverse Outcome Pathways (AOPs) and larger scale implementation into next generation hazard and risk predictions is restricted. The present study was therefore conducted to assess the effects of high-energy gamma radiation from cobalt-60 across multiple levels of Biological Organization (i.e., molecular, cellular, tissue, organ and individual) and characterize the major toxicity pathways leading to impaired reproduction in the model freshwater crustacean Daphnia magna (water flea). Following gamma exposure, a number of bioassays were integrated to measure relevant toxicological endpoints such as gene expression, reactive oxygen species (ROS), lipid peroxidation (LPO), neutral lipid storage, adenosine triphosphate (ATP) content, apoptosis, ovary histology and reproduction. A non-monotonic pattern was consistently observed across the levels of Biological Organization, albeit with some variation at the lower end of the dose-rate scale, indicating a complex response to radiation doses. By integrating results from different bioassays, a novel pathway network describing the key toxicity pathways involved in the reproductive effects of gamma radiation were proposed, such as DNA damage-oocyte apoptosis pathway, LPO-ATP depletion pathway, calcium influx-endocrine disruption pathway and DNA hypermethylation pathway. Three novel AOPs were proposed for oxidative stressor-mediated excessive ROS formation leading to reproductive effect, and thus introducing the world's first AOPs for non-chemical stressors in aquatic invertebrates

  • Effects of artificial ultraviolet B radiation on the macrophyte Lemna minor: a conceptual study for toxicity pathway characterization
    2020
    Co-Authors: Li Xie, Song You, Solhaug, Knut Asbjørn, Johnsen Bjørn, Olsen, Jorunn Elisabeth, Tollefsen Knut-erik
    Abstract:

    Macrophytes inhabit waterways around the world and are used in hydroponics or aquaponics for different purposes such as feed and wastewater treatment and are thus exposed to elevated levels of UVB from natural and artificial sources. Although high UVB levels are harmful to macrophytes, mechanistic understanding of irradiance-dependent effects and associated modes of action in non-UVB acclimated plants still remains low. The present study was conducted to characterise the irradiance-dependent mechanisms of UVB leading to growth inhibition in Lemna minor as an aquatic macrophyte model. The L. minor were continuously exposed to UVB (0.008–4.2 W m−2) and constant UVA (4 W m−2) and photosynthetically active radiation, PAR (80 µmol m−2 s−1) for 7 days. A suite of bioassays was deployed to assess effects on oxidative stress, photosynthesis, DNA damage, and transcription of antioxidant biosynthesis, DNA repair, programmed cell death, pigment metabolism and respiration. The results showed that UVB triggered both irradiance-dependent and target-specific effects at multiple levels of Biological Organization, whereas exposure to UVA alone did not cause any effects. Inhibition of photosystem II and induction of carotenoids were observed at 0.23 W m−2, whereas growth inhibition, excessive reactive oxygen species, lipid peroxidation, cyclobutane pyrimidine dimer formation, mitochondrial membrane potential reduction and chlorophyll depletion were observed at 0.5–1 W m−2. Relationships between responses at different levels of Biological Organization were used to establish a putative network of toxicity pathways to improve our understanding of UVB effects in aquatic macrophytes under continuous UVB exposures. Additional studies under natural illuminations were proposed to assess whether these putative toxicity pathways may also be relevant for more ecologically relevant exposure scenarios

  • Effects of artificial ultraviolet B radiation on the macrophyte Lemna minor: a conceptual study for toxicity pathway characterization
    'Springer Science and Business Media LLC', 2020
    Co-Authors: Li Xie, Song You, Solhaug, Knut Asbjørn, Johnsen Bjørn, Olsen, Jorunn Elisabeth, Tollefsen Knut-erik
    Abstract:

    Macrophytes inhabit waterways around the world and are used in hydroponics or aquaponics for different purposes such as feed and wastewater treatment and are thus exposed to elevated levels of UVB from natural and artificial sources. Although high UVB levels are harmful to macrophytes, mechanistic understanding of irradiance-dependent effects and associated modes of action in non-UVB acclimated plants still remains low. The present study was conducted to characterise the irradiance-dependent mechanisms of UVB leading to growth inhibition in Lemna minor as an aquatic macrophyte model. The L. minor were continuously exposed to UVB (0.008–4.2 W m−2) and constant UVA (4 W m−2) and photosynthetically active radiation, PAR (80 µmol m−2 s−1) for 7 days. A suite of bioassays was deployed to assess effects on oxidative stress, photosynthesis, DNA damage, and transcription of antioxidant biosynthesis, DNA repair, programmed cell death, pigment metabolism and respiration. The results showed that UVB triggered both irradiance-dependent and target-specific effects at multiple levels of Biological Organization, whereas exposure to UVA alone did not cause any effects. Inhibition of photosystem II and induction of carotenoids were observed at 0.23 W m−2, whereas growth inhibition, excessive reactive oxygen species, lipid peroxidation, cyclobutane pyrimidine dimer formation, mitochondrial membrane potential reduction and chlorophyll depletion were observed at 0.5–1 W m−2. Relationships between responses at different levels of Biological Organization were used to establish a putative network of toxicity pathways to improve our understanding of UVB effects in aquatic macrophytes under continuous UVB exposures. Additional studies under natural illuminations were proposed to assess whether these putative toxicity pathways may also be relevant for more ecologically relevant exposure scenarios.publishedVersio