Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 19 de 19
Filtrar
Más filtros










Base de datos
Intervalo de año de publicación
1.
Ambio ; 53(4): 517-533, 2024 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-38324120

RESUMEN

Drawing on collective experience from ten collaborative research projects focused on the Global South, we identify three major challenges that impede the translation of research on sustainability and resilience into better-informed choices by individuals and policy-makers that in turn can support transformation to a sustainable future. The three challenges comprise: (i) converting knowledge produced during research projects into successful knowledge application; (ii) scaling up knowledge in time when research projects are short-term and potential impacts are long-term; and (iii) scaling up knowledge across space, from local research sites to larger-scale or even global impact. Some potential pathways for funding agencies to overcome these challenges include providing targeted prolonged funding for dissemination and outreach, and facilitating collaboration and coordination across different sites, research teams, and partner organizations. By systematically documenting these challenges, we hope to pave the way for further innovations in the research cycle.


Asunto(s)
Resiliencia Psicológica , Humanos
2.
Ambio ; 52(9): 1462-1474, 2023 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-37184622

RESUMEN

This study makes an ecological economic comparison between three different rice farming strategies in the Mekong Delta. Interviews were made with 30 farmers with two crops of rice and low dikes (2RLd), 30 farmers with three crops of rice and high dikes (3RHd) and 18 farmers with two crops of rice and one crop of fish (2RF). 2RF farmers had the highest annual net income and benefit cost ratio, because of low production costs and high yields of rice and fish. 2RLd farmers had the lowest annual net income. 3RHd had the highest annual rice yield, but also used the highest amount of rice seeds and agrochemicals, generating the lowest benefit cost ratio. Most farmers (70%) preferred two crops because of a higher production efficiency. High dikes and frequent use of pesticides and fertilizers were seen to decrease the water and rice quality, connectivity and biodiversity in farms with three crops. It is concluded that rice farming with two crops, and especially if integrated with fish and applying IPM, provides a sustainable alternative to rice farming with three crops and high dikes, because it makes use of the high connectivity within the rice-field ecosystem for an efficient production of healthy food through increased recycling of nutrients and  natural pest control mechanisms.


Asunto(s)
Oryza , Plaguicidas , Animales , Ecosistema , Vietnam , Agricultura , Peces , Productos Agrícolas
3.
J Environ Manage ; 338: 117807, 2023 Jul 15.
Artículo en Inglés | MEDLINE | ID: mdl-37037143

RESUMEN

Increased agriculture and aquaculture production in the Mekong Delta during the last two decades has improved farmers' income, national export earnings and reduced poverty, but has also impacted on the environment and ecosystem services (ES) of importance to peoples' livelihoods and well-being. Through group discussions, interviews and questionnaires, this study assesses stakeholders' perceptions of the status and trends of ES in the Mekong Delta and how these have been influenced by agriculture development. 15 of 24 ES were assessed to be impacted negatively by agriculture intensification, and especially supporting and regulating ES (SRES). Only a few provisioning ES (PrES), related to farming, were assessed to be in a good and stable supply, because of human interventions to create favorable conditions for these ES. Among the ten highest ranked ES, eight belonged to PrES and two belonged to SRES. There was a positive correlation between rank and awareness of ES. The supply of most SRES was perceived to be in a low and declining status and assessed to be in a high need for improved management. Some ES, such as pest-control had been complemented with human-made substitutes, such as pesticides, which however sometimes weakened rather than strengthened the ES. Cultural ES (CES) were often ranked lower and of less management concern than the other groups of ES. It is concluded that future agriculture strategies need a more balanced management of ES for a long-term production of healthy food and increased resilience of the Mekong Delta to cope with future challenges, such as climate change and upstream dams.


Asunto(s)
Ecosistema , Plaguicidas , Humanos , Humedales , Agricultura , Renta , Conservación de los Recursos Naturales
4.
Environ Sci Pollut Res Int ; 25(17): 17207-17215, 2018 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-29713976

RESUMEN

The combined effect of Vitashield 40EC (chlorpyrifos ethyl-CPF) and Bassa 50EC (fenobucarb-F) was compared with the effects from exposure to the two pesticides separately, by measuring the brain acetylcholinesterase (AChE) activity in climbing perch fingerlings (Anabas testudineus). The experiment was conducted under controlled laboratory conditions and included three treatments containing 0.173 mg/L of CPF, 1.137 mg/L of F, 0.173 mg/L of CPF + 1.137 mg/L of F (M), and a control. The inhibition of the brain AChE activity in fish exposed to F was weaker and shorter than in fish exposed to CPF. The inhibition by the mixture of CPF and F was significantly lower and less prolonged than the inhibition by only CPF but significantly higher than the inhibition by only F.


Asunto(s)
Acetilcolinesterasa/metabolismo , Encéfalo/enzimología , Carbamatos/química , Insecticidas/farmacología , Compuestos Organotiofosforados/química , Percas/metabolismo , Plaguicidas/farmacología , Acetilcolinesterasa/química , Animales , Cloropirifos , Insecticidas/toxicidad
5.
Environ Sci Pollut Res Int ; 25(14): 13322-13334, 2018 May.
Artículo en Inglés | MEDLINE | ID: mdl-27854060

RESUMEN

This study evaluates the risks of pesticides applied in rice-fish and rice farming, with and without integrated pest management (IPM) strategies, to non-target aquatic organisms in two provinces of the Mekong Delta, Vietnam. Pesticide inventories and application patterns were collected from 120 Vietnamese farmers through interviews. Risks were assessed using (1) Pesticide RIsks in the Tropics to Man, Environment, and Trade (PRIMET), a first-tier model, which calculates predicted environmental concentrations (PECs) of pesticides in the rice field, based on the compound's physico-chemical properties and the application pattern, and then compares the PECs to safe concentrations based on literature data, and (2) species sensitivity distribution (SSD), a second-tier assessment model using species sensitivity distributions to calculate potentially affected fraction (PAF) of species based on the PECs from PRIMET. Our results show that several of the used insecticides pose a high risk to fish and arthropods and that the risks are higher among rice farmers than among rice-fish farmers. This study indicates that the PRIMET model in combination with SSDs offer suitable approaches to help farmers and plant protection staff to identify pesticides that may cause high risk to the environment and therefore should be substituted with safer alternatives.


Asunto(s)
Insecticidas/análisis , Plaguicidas/análisis , Agricultura , Animales , Organismos Acuáticos , Agricultores , Granjas , Humanos , Insecticidas/química , Oryza , Control de Plagas , Plaguicidas/química , Vietnam
6.
Sci Total Environ ; 619-620: 319-327, 2018 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-29154050

RESUMEN

This study assesses the use of pesticides and the attitude to pest management strategies among rice and rice-fish farmers in the Can Tho and Tien Giang provinces in Vietnam. Interviews were made with 80 farmers. The farmers were divided in to farmers cultivating only rice with a high use (RHP) and low use (RLP) of pesticides, and farmers cultivating rice and fish with a high use (RFHP) and low use (RFLP) of pesticides. 80% of the HP farmers relied mainly on pesticides to control pests, while >80% of the LP farmers also applied IPM strategies. Insecticides were the most commonly used pesticides. 85% of all farmers experienced health effects from using pesticides. 80% of the farmers felt that the yield of fish had decreased over the last three years, and that this mainly was caused by pesticides. The RFHP farmers had lower fish survival and fish yields as compared to the RFLP farmers. The RFHP farmers also had significant lower rice yields than the RFLP farmers, and there were significant correlations between both decreased fish yields and rice yields with increased use of pesticides among rice-fish farmers. Increased rice yields were positively correlated with increased fish survival, indicating the synergistic effects between rice and fish production. Overall, the RFLP farmers had the highest income of the four farmers´ groups, while RFHP farmers had the lowest income. This shows that rice-fish farming provides a competitive and sustainable alternative to intensive rice-farming, but only if the farmer restricts the use of pesticides. This would not only help to reduce the production costs, but also to decrease environmental and health effects, and it is proposed that rice-fish farming with a low use of pesticides provides an attractive alternative to rice-monocropping for a sustainable and diversified food production in the Mekong Delta.


Asunto(s)
Agricultura/métodos , Peces , Oryza/crecimiento & desarrollo , Plaguicidas , Animales , Vietnam
7.
Gen Comp Endocrinol ; 257: 130-136, 2018 02 01.
Artículo en Inglés | MEDLINE | ID: mdl-28479083

RESUMEN

Rapid, androgen actions initiated at the cell surface have been reported in a variety of vertebrate cells, including several macrophage and prostate cancer cell lines that lack the nuclear androgen receptor. However, until recently the identity of the novel membrane androgen receptor (mAR) mediating these nonclassical androgen actions remained unknown. In 2014, a novel mAR unrelated to nuclear androgen receptors was identified in Atlantic croaker ovaries as the zinc transporter protein, ZIP9. ZIP9 is one of the 14 members of the ZIP (ZRT-and Irt-like Protein, SLC39A) family that regulates zinc homeostasis by transporting zinc across cell and organelle membranes into the cytoplasm. Zinc is a micronutrient critical for the maintenance of physiological and cellular processes, such as development, growth, protein assembly and activity, signaling, and apoptosis. Both croaker ZIP9 and human ZIP9 proteins have the binding characteristics of high affinity, specific mARs, and are coupled to G proteins. Testosterone induces apoptosis through ZIP9 in croaker granulosa cells and in human breast and prostate cancer cells by a unique mechanism involving increases in both second messengers and intracellular free zinc concentrations. ZIP9 also mediates testosterone regulation of tight junction formation in Sertoli cells and nonclassical testosterone signaling in spermatogenic cells. ZIP9 acts through several signal transduction pathways, a stimulatory G protein (Gs) in granulosa cells, an inhibitory one (Gi) in cancer cells, and a Gq11 one (Gnα11) in spermatogenic cells. ZIP9 has a very broad tissue distribution and is predicted to mediate numerous and diverse nonclassical androgen actions in vertebrates.


Asunto(s)
Proteínas Portadoras/metabolismo , Perciformes , Receptores Androgénicos/metabolismo , Animales , Apoptosis , Femenino , Humanos , Masculino , Zinc/metabolismo
8.
Environ Sci Pollut Res Int ; 25(14): 13226-13234, 2018 May.
Artículo en Inglés | MEDLINE | ID: mdl-27250094

RESUMEN

Organophosphates (e.g. chlorpyrifos ethyl) and carbamates (e.g. fenobucarb) are commonly used to control a wide range of pests in rice fields of the Mekong Delta in Vietnam. This study assesses the combined effect of chlorpyrifos ethyl (CPF) and fenobucarb (F), applied at concentrations used by rice farmers, on the brain acetylcholinesterase (AChE) activity in climbing perch fingerlings from rice fields in the Mekong Delta. It also investigates if Pyridine-2-aldoxime methiodide (2-PAM) can be used to reactivate cholinesterase that has been blocked by CPF. Three days after spraying, the water concentrations of both insecticides decreased quickly below the detection levels. However, the brain AChE activity in fish was inhibited for more than 7 days. The results indicate a quicker but less prolonged inhibition of the brain AChE activity by the mixture than by only CPF. The inhibition levels were above 70 % only during the first 48 h, which could explain why all fish survived. 2-PAM resulted in a significant reactivation of the cholinesterase blocked by a combination of CPF and F, and it is proposed that the reactivation by 2-PAM could provide a way to assess the AChE inhibition levels in organisms, when no unexposed individuals are available as controls. The results indicate that the current use of CPF and F in rice farming in the Mekong Delta is likely to cause negative effects on non-target organisms. Many of these effects may be sub-lethal, and there is a need to develop biomarkers that are relevant, inexpensive and easy to apply. The results show that brain AChE in climbing perch fingerling is a relevant biomarker for monitoring of exposure to, and sub-lethal impacts from organophosphates and carbamates under tropical conditions in developing countries.


Asunto(s)
Carbamatos/toxicidad , Insecticidas/toxicidad , Compuestos Organotiofosforados/toxicidad , Oryza , Percas , Acetilcolinesterasa/metabolismo , Animales , Encéfalo/efectos de los fármacos , Encéfalo/enzimología , Cloropirifos , Exposición a Riesgos Ambientales , Compuestos de Pralidoxima/farmacología , Vietnam , Contaminantes Químicos del Agua/toxicidad
9.
Sci Total Environ ; 584-585: 1138-1146, 2017 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-28159303

RESUMEN

Metals released into the environment continue to be of concern for human health. However, risk assessment of metal exposure is often based on total metal levels and usually does not take bioavailability data, metal speciation or matrix effects into consideration. The continued development of biological endpoint analyses are therefore of high importance for improved eco-toxicological risk analyses. While there is an on-going debate concerning synergistic or additive effects of low-level mixed exposures there is little environmental data confirming the observations obtained from laboratory experiments. In the present study we utilized qRT-PCR analysis to identify key metal response genes to develop a method for biomonitoring and risk-assessment of metal pollution. The gene expression patterns were determined for juvenile zebrafish exposed to waters from sites down-stream of a closed mining operation. Genes representing different physiological processes including stress response, inflammation, apoptosis, drug metabolism, ion channels and receptors, and genotoxicity were analyzed. The gene expression patterns of zebrafish exposed to laboratory prepared metal mixes were compared to the patterns obtained with fish exposed to the environmental samples with the same metal composition and concentrations. Exposure to environmental samples resulted in fewer alterations in gene expression compared to laboratory mixes. A biotic ligand model (BLM) was used to approximate the bioavailability of the metals in the environmental setting. However, the BLM results were not in agreement with the experimental data, suggesting that the BLM may be overestimating the risk in the environment. The present study therefore supports the inclusion of site-specific biological analyses to complement the present chemical based assays used for environmental risk-assessment.


Asunto(s)
Monitoreo del Ambiente , Metales , Contaminantes Químicos del Agua , Pez Cebra/genética , Animales , Expresión Génica , Humanos , Minería , Medición de Riesgo
10.
Sustain Sci ; 12(1): 137-154, 2017.
Artículo en Inglés | MEDLINE | ID: mdl-30174748

RESUMEN

The increased rice production in the Mekong Delta during the last two decades has improved agricultural income and reduced poverty, but it has also had negative impacts on the environment and human health. This study shows that integrated rice-fish farming and integrated pest management strategies provide sustainable options to intensive rice farming, because of a more balanced use of multiple ecosystem services that benefit the farmers' health, economy and the environment. The study investigates and compares farming strategies among 40 rice and 20 rice-fish farmers in two locations in the Mekong Delta. Production costs and income are used to compare the systems' financial sustainability. The farmers' perception on how their farming practices influence on ecosystem services and their livelihoods are used as an indication of the systems' ecological and social sustainability. Although rice-fish farmers used lower amount of pesticides and fertilisers than rice farmers, there were no statistical differences in their rice yields or net income. Rice was seen as the most important ecosystem service from rice fields and related wetlands, but also several other ecosystem services, such as water quality, aquatic animals, plants, habitats, and natural enemies to pests, were seen as important to the farmers' livelihoods and wellbeing. All farmers perceived that there had been a general reduction in all these other ecosystem services, due to intensive rice farming during the last 15 years, and that they will continue to decline. The majority of the farmers were willing to reduce their rice yields slightly for an improved quality of the other ecosystem services.

11.
Bull Environ Contam Toxicol ; 97(1): 98-104, 2016 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-27075585

RESUMEN

This study assesses the effects of sequential applications of the insecticides Bassa 50EC (fenobucarb-F) and Vitashield 40EC (chlorpyrifos ethyl-CPF), sprayed at concentrations used by rice farmers in the Mekong Delta, on the brain acetylcholinesterase (AChE) in climbing perch fingerlings. After spraying the pesticides on the rice fields, the water concentrations of both insecticides decreased below the detection levels within 3 days. The sequential applications caused significant inhibition on the brain AChE activity in the exposed fish. The inhibition by F was quicker, but less prolonged, than for CPF. The inhibition levels caused by the sequential applications were lower than those caused by only CPF and by a mixture of CPF and F. The results indicate that sequential applications of pesticides could have a negative impact on aquatic organisms and fish yields, with implication for the aquatic biodiversity, local people's livelihood and the aquaculture industry in the Mekong Delta.


Asunto(s)
Acetilcolinesterasa/metabolismo , Carbamatos/toxicidad , Insecticidas/toxicidad , Compuestos Organotiofosforados/toxicidad , Oryza , Percas/metabolismo , Animales , Encéfalo/enzimología , Cloropirifos , Vietnam
12.
Arch Environ Contam Toxicol ; 69(4): 515-24, 2015 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-26135300

RESUMEN

The high use of pesticides in intensive rice farming in the Mekong Delta constitutes a potential hazard to the environment and to people's health. Chlorpyrifos ethyl (CPF) is a commonly used organophosphate (OP) insecticide, but information about its potential negative impacts on the aquatic environment in the Mekong Delta is scarce. Both acute and subacute toxicity tests were performed in a static nonrenewable system to investigate the effects of CPF on brain acetylcholinesterase (AChE) activity in native climbing perch fingerlings (Anabas testudineus, Bloch, 1972). Environmental parameters, such as dissolved oxygen, water temperature, and pH, were similar to field conditions in the Mekong Delta. In a 96-h lethal concentration (LC50) test, fingerlings of climbing perch were randomly exposed to five levels of CPF ranging from 0.8 to 4.5 ppm. Five sublethal levels of CPF (1, 5, 10, 15, and 20 % of the 96-h LC50 value) were tested to assess the sensitivity and recovery of the brain AChE activity in climbing perch fingerlings exposed to CPF. The results showed that CPF were moderately toxic to climbing perch with a 96-h median LC50 of 1.73 ppm. CPF also caused long-term AChE inhibition with 70 % inhibition remaining after 96 h for the four highest test concentrations. The recovery of brain AChE activity in fish placed in CPF-free water was very slow, and after 7 days the brain AChE activity was still significant lower in fish from the four highest concentrations compared with the control. The results from this study indicate that OP insecticides, such as CPF, can have long-lasting sublethal effects on aquatic species in the Mekong Delta.


Asunto(s)
Acetilcolinesterasa/metabolismo , Insecticidas/toxicidad , Compuestos Organotiofosforados/toxicidad , Percas/fisiología , Contaminantes Químicos del Agua/toxicidad , Animales , Cloropirifos , Inhibidores de la Colinesterasa/toxicidad , Pruebas de Toxicidad Aguda
13.
Ecotoxicol Environ Saf ; 117: 34-40, 2015 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-25828891

RESUMEN

Climbing perch is commonly harvested in rice fields and associated wetlands in the Mekong Delta. Despite its importance in providing food and income to local households, there is little information how this fish species is affected by the high use of pesticides in rice farming. Organophosphate insecticides, such as chlorpyrifos ethyl, which are highly toxic to aquatic organisms, are commonly used in the Mekong Delta. This study shows that the brain acetylcholinesterase (AChE) activity in climbing perch fingerlings cultured in rice fields, was significantly inhibited by a single application of chlorpyrifos ethyl, at doses commonly applied by rice farmers (0.32-0.64 kg/ha). The water concentration of chlorpyrifos ethyl decreased below the detection level within 3 days, but the inhibition of brain AChE activity remained for more than 12 days. In addition, the chlorpyrifos ethyl treatments had a significant impact on the survival and growth rates of climbing perch fingerlings, which were proportional to the exposure levels. The results indicate that the high use of pesticides among rice farmers in the Mekong Delta could have a negative impact on aquatic organisms and fish yields, with implications for the aquatic biodiversity, local people's livelihoods and the aquaculture industry in the Mekong Delta.


Asunto(s)
Acetilcolinesterasa/metabolismo , Encéfalo/efectos de los fármacos , Cloropirifos/toxicidad , Insecticidas/toxicidad , Percas , Agricultura , Animales , Encéfalo/enzimología , Oryza , Plaguicidas/toxicidad , Vietnam
14.
Reprod Biol Endocrinol ; 7: 46, 2009 May 14.
Artículo en Inglés | MEDLINE | ID: mdl-19442269

RESUMEN

Spiggin is an adhesive glycoprotein produced in the kidney of sticklebacks during the breeding season and is subsequently secreted into the urinary bladder from where it is employed for nest building. Since the production of the protein has been shown to be under androgenic control, spiggin has been suggested to be a useful biomarker for androgenic substances in the environment. In this study, two polyclonal spiggin antibodies based on synthetic peptides and one polyclonal antibody directed against native spiggin have been characterized. The antibodies ability to identify spiggin was investigated by quantitative immunoassay. For both peptide antibodies the quantification range was determined to be between 1 and 80 ng spiggin and determination of renal spiggin levels from immature and mature males displayed a 15-fold increase in total spiggin content of the kidney resulting in a 6-fold increase in male kidney weight due to hypertrophy. The kidney somatic index (KSI) was found to correlate well with the total renal spiggin content and therefore it appears that KSI in sticklebacks could be used as an initial method to identify substances displaying androgenic effects. Furthermore, western blot analysis revealed that the polyclonal antibodies recognize different spiggin isoforms and that spiggin can be detected in the urinary bladder and kidney of both males and female sticklebacks. In order to develop a quantitative detection method for native spiggin it is necessary to produce a standard that can be used in a bioassay. Due to the adhesive and polymerization characteristics of spiggin the protein is difficult to use as a standard in bioassays. So far spiggin has been shown to exist in at least 14 isoforms, all of which contain polymerization domains. To overcome the solubility problem we have produced recombinant spiggin gamma, with only one polymerization domain, that can be expressed in E. coli. Western blot analysis demonstrated that the polyclonal antibodies were able to detect recombinant spiggin gamma protein in bacterial cell lysate, suggesting that it may be developed into a useful source of standard spiggin to be used for quantitative determination of androgen induced spiggin production in sticklebacks.


Asunto(s)
Especificidad de Anticuerpos , Ensayo de Inmunoadsorción Enzimática/métodos , Proteínas de Peces/inmunología , Proteínas de Peces/metabolismo , Reproducción/fisiología , Smegmamorpha/metabolismo , Secuencia de Aminoácidos , Animales , Anticuerpos/farmacología , Western Blotting , Peso Corporal/fisiología , Femenino , Proteínas de Peces/genética , Riñón/metabolismo , Masculino , Datos de Secuencia Molecular , Proteínas Recombinantes/genética , Proteínas Recombinantes/inmunología , Proteínas Recombinantes/metabolismo , Testosterona/análogos & derivados , Testosterona/farmacología
15.
Environ Health Perspect ; 117(12): 1853-9, 2009 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-20049203

RESUMEN

BACKGROUND: Reported incidences of prostate cancer and masculinization of animals indicate a release of compounds with androgenic properties into the environment. Large numbers of environmental pollutants have been screened to identify such compounds; however, not until recently was 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (TBECH) identified as the first potent activator of the human androgen receptor (hAR). TBECH has been found in beluga whales and bird eggs and has also been found to be maternally transferred in zebrafish. OBJECTIVES: In the present study we investigated interaction energies between TBECH diastereomers (alpha, beta, gamma, and delta) and the hAR, and their ability to activate the receptor and induce prostate-specific antigen (PSA) expression in vitro. METHODS: We performed computational modeling to determine interaction energies between the ligand and the AR ligand-binding site, and measured in vitro competitive binding assays for AR by polarization fluorometry analysis. We used enzyme-linked immunosorbent assays to determine PSA activity in LNCaP and HepG2 cells. RESULTS: We found the gamma and delta diastereomers to be more potent activators of hAR than the alpha and beta diastereomers, which was confirmed in receptor binding studies. All TBECH diastereomers induced PSA expression in LNCaP cells even though the AR present in these cells is mutated (T877A). Modeling studies of LNCaP AR revealed that TBECH diastereomers bound to the receptor with a closer distance to the key amino acids in the ligand-binding domain, indicating stronger binding to the mutated receptor. CONCLUSIONS: The present study demonstrates the ability of TBECH to activate the hAR, indicating that it is a potential endocrine disruptor.


Asunto(s)
Ciclohexanos/toxicidad , Disruptores Endocrinos/toxicidad , Retardadores de Llama/toxicidad , Receptores Androgénicos/efectos de los fármacos , Línea Celular Tumoral , Ensayo de Inmunoadsorción Enzimática , Células Hep G2 , Humanos , Masculino , Neoplasias de la Próstata/patología , Receptores Androgénicos/metabolismo , Estereoisomerismo
16.
Environ Toxicol Chem ; 25(6): 1465-73, 2006 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-16764463

RESUMEN

The fate of chiral organochlorine compounds (OCs) and selected metabolites in exposed Arctic char (Salvelinus alpinus) was investigated. The contaminants alpha-hexachlorocyclohexane (alpha-HCH), cis-chlordane, 13C4-heptachlor, o,p'-DDT, and the atropisomeric chlorinated biphenyls (CBs) 95, 132, 136, 149, and 174 were solved in peanut oil and injected into the peritoneal cavity. The exposed fish were sampled three times during a five-week period, and the OC residues and detected metabolites (heptachlorexo-epoxide) were quantified in muscle and liver tissues by chiral and achiral gas chromatography-mass spectrometry and gas chromatography-electron-capture detection. Peak concentrations were reached after one to two weeks, and thereafter, the levels declined. At the end of the experiment, liver concentrations had decreased 76 to 92% relative to peak concentrations, whereas muscle concentrations showed a moderate decline (5-38%), with the exception of alpha-HCH (91%). Hydrophobicity and steric hindrance were shown to influence the assimilation process, and a significant linear relationship between the product of the steric hindrance coefficients and the inverse of the octanol-water partition coefficients (Kow) versus peak concentration was found for the CBs (r2 = 0.86, p = 0.02). The assimilation of the contaminants into muscle and liver tissues generally resulted in racemic mixtures, whereas elimination was enantioselective for alpha-HCH, cis-chlordane, o,p'-DDT, CB-132, and CB-136. The chiral heptachlor metabolite 13C4-heptachlor-exo-epoxide was formed in the fish. The enantiomeric composition of the formed metabolite indicated racemic formation, whereas the elimination process appeared to be enantioselective.


Asunto(s)
Hidrocarburos Clorados/farmacocinética , Animales , Cromatografía de Gases y Espectrometría de Masas , Hidrocarburos Clorados/administración & dosificación , Inyecciones Intraperitoneales , Hígado/metabolismo , Músculos/metabolismo , Estereoisomerismo , Distribución Tisular , Trucha
17.
Steroids ; 71(4): 310-6, 2006 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-16289637

RESUMEN

The identities of the membrane receptors mediating the majority of rapid, cell surface-initiated, nongenomic (i.e. nonclassical) steroid actions described to date are unclear. Two novel 7-transmembrane spanning proteins, representing two distinct classes of steroid membrane receptors, membrane progestin receptor alpha (mPRalpha) and a membrane estrogen receptor (mER), GPR30, have recently been identified in several vertebrate species. Evidence that both receptors activate G-proteins and function as G-protein coupled receptors (GPCRs) is briefly reviewed. New data on progestin actions on fish gametes suggest a widespread involvement of mPRalpha in oocyte maturation and sperm hyperactivity in this vertebrate group. Information on the second messenger pathways activated upon estrogen binding to a membrane estrogen receptor in croaker gonads and preliminary evidence for the presence of a GPR30-like protein in fish gonads are discussed. Finally, initial characterization of the ligand binding, G-protein activation and molecular size of a membrane androgen receptor (mAR) in croaker ovaries suggests the presence of a third unique steroid receptor in fish gonads that also may function as a GPCR.


Asunto(s)
Ovario/metabolismo , Perciformes/metabolismo , Receptores Acoplados a Proteínas G/fisiología , Testículo/metabolismo , Animales , Femenino , Masculino , Ovario/fisiología , Perciformes/fisiología , Receptores Androgénicos/fisiología , Receptores de Estrógenos/fisiología , Receptores de Progesterona/fisiología , Testículo/fisiología
18.
Reprod Biol Endocrinol ; 2: 62, 2004 Sep 02.
Artículo en Inglés | MEDLINE | ID: mdl-15345061

RESUMEN

This study was performed to investigate stress effects on the synthesis of egg yolk precursor, vitellogenin (Vtg) in Arctic char (Salvelinus alpinus). In particular the effect of cortisol (F) was determined since this stress hormone has been suggested to interfere with vitellogenesis and is upregulated during sexual maturation in teleosts. Arctic char Vtg was purified and polyclonal antibodies were produced in order to develop tools to study regulation of vitellogenesis. The Vtg antibodies were used to develop an enzyme-linked immunosorbent assay. The corresponding Vtg cDNA was cloned from a hepatic cDNA library in order to obtain DNA probes to measure Vtg mRNA expression. Analysis of plasma from juvenile Arctic char, of both sexes, exposed to different steroids showed that production of Vtg was induced in a dose dependent fashion by 17beta-estradiol (E2), estrone and estriol. Apart from estrogens a high dose of F also upregulated Vtg. In addition, F, progesterone (P) and tamoxifen were tested to determine these compounds ability to modulate E2 induced Vtg synthesis at both the mRNA and protein level. Tamoxifen was found to inhibit E2 induced Vtg mRNA and protein upregulation. P did not alter the Vtg induction while F reduced the Vtg protein levels without affecting the Vtg mRNA levels. Furthermore the inhibition of Vtg protein was found to be dose dependent. Thus, the inhibitory effect of F on Vtg appears to be mediated at the post-transcriptional level.


Asunto(s)
Estradiol/metabolismo , Estradiol/farmacología , Antagonistas de Estrógenos/farmacología , Hidrocortisona/farmacología , Procesamiento Postranscripcional del ARN/efectos de los fármacos , Testosterona/análogos & derivados , Trucha/genética , Vitelogénesis/efectos de los fármacos , Animales , Clonación Molecular/métodos , Corticosterona/farmacología , Cortisona/farmacología , Progesterona/farmacología , ARN/genética , Procesamiento Postranscripcional del ARN/genética , Testosterona/farmacología , Vitelogénesis/genética
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA
...