Gene transcription in Daphnia magna: effects of acute exposure to a carbamate insecticide and an acetanilide herbicide.

Daphnia magna is a key invertebrate in the freshwater environment and is used widely as a model in ecotoxicological measurements and risk assessment. Understanding the genomic responses of D. magna to chemical challenges will be of value to regulatory authorities worldwide. Here we exposed D. magna to the insecticide methomyl and the herbicide propanil to compare phenotypic effects with changes in mRNA expression levels. Both pesticides are found in drainage ditches and surface water bodies standing adjacent to crops. Methomyl, a carbamate insecticide widely used in agriculture, inhibits acetylcholinesterase, a key enzyme in nerve transmission. Propanil, an acetanilide herbicide, is used to control grass and broad-leaf weeds. The phenotypic effects of single doses of each chemical were evaluated using a standard immobilisation assay. Immobilisation was linked to global mRNA expression levels using the previously estimated 48h-EC(1)s, followed by hybridization to a cDNA microarray with more than 13,000 redundant cDNA clones representing >5000 unique genes. Following exposure to methomyl and propanil, differential expression was found for 624 and 551 cDNAs, respectively (one-way ANOVA with Bonferroni correction, P

A comparative study on the relationship between acetylcholinesterase activity and acute toxicity in Daphnia magna exposed to anticholinesterase insecticides

Acetylcholinesterase (AChE) activity was measured in Daphnia magna that had been exposed to four organophosphates (OPs; parathion, chlorpyrifos, malathion, and acephate) and one carbamate (propoxur) for 48 h. These results were related to acute toxicity (median effective concentration [EC50] for immobility). For the four OPs, the EC50s were 7.03 pM, 3.17 pM, 10.56 pM, and 309.82 microM, respectively. The EC50 for propoxur was 449.90 pM. Reduction in AChE activity was directly related to an increase in immobility in all chemicals tested. However, the ratio between the EC50 and the AChE median inhibiting concentration ranged from 0.31 to 0.90. A 50% reduction in AChE activity generally was associated with detrimental effects on mobility. However, for acephate, high levels of AChE inhibition (70%) were observed in very low concentrations and were not associated with immobility. In addition, increasing the concentration of acephate further had a slight negative effect on AChE activity but a strong detrimental effect on mobility. Binding sites other than AChE possibly are involved in acephate toxicity to D. magna. Our findings demonstrate different associations between AChE inhibition and toxicity when different chemicals are compared. Therefore, the value of using AChE activity as a biomarker in D. magna will be dependent on the chemical tested.

Efeitos de florações de cianobactérias sobre os cladóceros ceriodaphnia dubia e daphnia gessneri

Cyanobacterial blooms are common in eutrophic reservoirs in Brazilian northeastern semi-arid. Given this reality, the present study aimed to analyze the effect of potentially toxic cyanobacterial blooms in Gargalheiras reservoir (semi-arid) on the cladocerans Ceriodaphnia dubia and Daphnia gessneri. In vitro chronic bioassays were performed with reservoir water dilutions from August/2011 to May/2012 and the following effects were evaluated on: intrinsic rate of population growth (r), reproductive parameters (age of first reproduction and fecundity per capita) and cladocerans movements. Phytoplankton was dominated by Cylindrospermopsis raciborskii and Planktothrix agardhii and saxitoxin and microcystin were detected in reservoir water. In most months C. dubia showed differences in r between control (absence of cyanobacteria) and treatments, and has shown negative effects on reproductive parameters. In all months paralysis of swimming movements was observed in C. dubia when both C. raciborskii and saxitoxin (cyanotoxin neurotoxic) were present in water. While C. dubia was sensitive to the reservoir water containing cyanobacteria, D. gessneri showed less intense negative effects in r and reproductive parameters. Furthermore, D. gessneri showed no paralysis of swimming movements. These results support the hypothesis in the literature that D. gessneri is resistant to the Cylindrospermopsis effects. The clone‟s life history may be a key to understand the results. The C. dubia clone, isolated from eutrophicated environment, is in the lab for ten years and it is an exotic species in Brazil. D. gessneri is a common species in the country and this clone was isolated from the Gargalheiras reservoir (where there are constant blooms of potentially toxic cyanobacteria) a year ago. Perhaps the recent contact with cyanobacteria explain the higher resistance presented by this D. gessneri clone. In conclusion, the cladocerans studied have different levels of sensitivity to cyanobacteria, characterizing species-specific responses

Acute toxicity and environmental risk of teflubenzuron to Daphnia magna, Poecilia reticulata and Lemna minor in the absence and presence of sediment

This study aimed to estimate the acute toxicity of teflubenzuron (1-(3,5-dichloro-2,4-difluorophenyl)-3-(2,6-difluorobenzoyl)urea) (TFB) for Daphnia magna, Lemna minor and Poecilia reticulata, in the absence and presence of sediment; evaluate the effect of sediment on the TFB bioavailability; and to classify this insecticide according to its environmental poisoning risk for agricultural and aquaculture uses. The tests of TFB acute toxicity were conducted in static system in a completely randomized design with increasing TFB concentrations, and a control group. The TFB has been classified according to the estimated values of EC50 and LC50 by its acute toxicity and environmental risk. The sediment significantly reduced toxicity and bioavailability of TFB in water column. Therefore, the insecticide can be classified as being highly toxic to Daphnia magna, which means the agricultural and aquacultural uses of TFB pose a high risk of environmental toxicity to non-target organisms. However, it was practically non-toxic to L. minor and P. reticulata. © 2013 Copyright Taylor and Francis Group, LLC.

Avaliação ecotoxicológica e risco ambiental dos inseticidas utilizados no controle da larva de Aedes aegypti para Daphnia magna, Lemna minor e peixes

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Toxicidade aguda e risco ambiental do diflubenzuron para Daphnia magna, Poecilia reticulata e Lemna minor na ausência e presença de sedimento

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Toxidade aguda e risco ambiental do inseticida teflubenzuron para Daphnia magna, Lemna minor e Poecilia reticulata

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Análise temporal da composição, abundância, diversidade dos Cladocera e crescimento alométrico da Daphnia spp. O. F. Müeller, 1785 na Lagoa do Camargo, lateral ao Rio Paranapanena em sua zona de desembocadura na Represa do Jurumirim

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

ECOTOXICITY AND ENVIRONMENTAL RISK ASSESSMENT OF LARVICIDES USED IN THE CONTROL OF Aedes aegypti TO Daphnia magna ( CRUSTACEA, CLADOCERA)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Vaccination of grazing calves with antigens from the intestinal membranes of Haemonchus contortus: effects against natural challenge with Haemonchus placei and Haemonchus similis

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Host-specificity and morphometrics of female Haemonchus contortus, H. placei and H. similis (Nematoda: Trichostrongylidae) in cattle and sheep from shared pastures in Sao Paulo State, Brazil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Detection of hormones in surface and drinking water in Brazil by LC-ESI-MS/MS and ecotoxicological assessment with Daphnia magna

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Ultrastructure of the Interface Between Stages of Eimeria funduli/i> (Apicomplexa) and Hepatocytes of the Longnose Killifish, Fundulus similis

The interface between stages of Eimeria funduli and hepatocytes of the experimentally infected killifish Fundulus similis was studied ultrastructurally. Parasitophorous vacuoles (PV's) in which meronts, macrogamonts, and microgamonts developed were lined by an inner, smooth membrane and an outer, ribosome-studded membrane. The outer membrane bordered on the cytoplasm of the host cell, whereas the inner one limited the PV. The origins of these membranes have not been determined with certainty, but images were observed in which both membranes appeared to be continuous with the outer nuclear membrane of the host cell. Furthermore, the outer PV membrane was continuous with membranes of rough endoplasmic reticulum in the host cell. For stages which were rapidly growing or differentiating, the inner membrane blebbed into the PV. Blebbing ceased and ribosomes detached from the outer membrane after maturation of the meront or fertilization of the macrogamont. Blebbing appears to be a mechanism by which nutrients transfer from the host to the parasite. During sporogony, the inner PV membrane acquired a thin layer of electron dense material, but otherwise membranes lining the PV remained intact. The two PV membranes, probably together with dense material of parasitic origin lining the inner membrane, appear to serve as the oocyst wall enclosing the sporocysts until they are released in the intermediate host.

Ctenosaura similis (Black Spiny-Tailed Iguana), ,i>Gopherus Polyphemus (Gopher Tortoise) Concurrent Burrow Use

Ctenosaura similis is exotic to Florida (Meshaka et al. 2004. The Exotic Amphibians and Reptiles of Florida, Krieger Publ. Co., Malabar, Florida. 155 pp.), whereas Gopherus polyphemus is listed as a species of special concern by the state of Florida (Florida Wildlife Code Chap. 39 F.A.C.), and as a threatened species by the Florida Committee on Rare and Endangered Plants and Animals (FCREPA) (Moler 1992. Rare and Endangered Biota of Florida: Volume III, Reptiles and Amphibians. University Press of Florida, Gainesville, Florida. 291 pp.).