Ef fects of Dieldrin on Life Stages of the African Catfish,Clarias gariepinus(Burchell)

Borokini

2014

Advances in Zoology

Raphia hookerifruits are used for fishing in Nigeria due to their ichthyotoxic properties. This study investigated the toxic effects ofR. hookerion the reproductive capacity ofClarias gariepinus. The results from both short-term (96-hour test) and long-term (3-month sublethal test) bioassays revealed a linear relationship betweenR. hookeriextract dose and negative effects on the catfish. The percentage survival of both sexes of the catfish decreased with increasing extract concentration at short-term exposure, with LC50values of 600 mg/L and 800 mg/L for male and female, respectively. At long-term exposure, the reproductive capacity of 10–12-month-old male and female brood-stocks diminished at relatively higher concentrations ofR. hookerifruit extract, with the gravid females producing fewer and mostly unviable eggs. The fruit extract also affected the eggs’ hatchability and fry survival when the exposed gravid females were treated with pituitary hormone and sperms from unexposed males, while the exposed males were unable to sexually stimulate female brooders. Sperms and pituitary hormone from exposed males were infertile, leading to low percentage of hatched eggs and mortality of the few hatched fries within 24 hours. These results confirmed the ethnobotanical use of this fruit extract for fishing in Nigeria.

Section: Discussionsupporting

confidence: 69%

Sublethal Effects of Methanolic Extract of Raphia hookeri on the Reproductive Capacity of Clarias gariepinus

Borokini

2014

Advances in Zoology

“…In catfish, dieldrin has been shown to bind GABA-A receptors in P2 membrane preparations from brain with relatively high affinity (IC 50 = 592.5 ± 105 nM; Carr et al, 1999). In addition, dieldrin is highly lipophilic and studies in teleost fishes have demonstrated that dieldrin bioaccumulates in fatty tissues such as the brain and liver (Lamai et al, 1999; Satyanarayan et al, 2005). There is also evidence that dieldrin-mediated neurotoxicity occurs in the teleostean CNS.…”

Section: Introductionmentioning

confidence: 99%

Effects of acute dieldrin exposure on neurotransmitters and global gene transcription in largemouth bass (Micropterus salmoides) hypothalamus

et al. 2010

Exposure to dieldrin induces neurotoxic effects in the vertebrate CNS and disrupts reproductive processes in teleost fish. Reproductive impairment observed in fish by dieldrin is likely the result of multiple effects along the hypothalamic-pituitary-gonadal axis but the molecular signaling cascades are not well characterized. To better elucidate the mode of action of dieldrin in the hypothalamus, this study measured neurotransmitter levels and examined the transcriptomic response in female largemouth bass (LMB) to an acute treatment of dieldrin. Male and female LMB were injected with either vehicle or 10 mg dieldrin/kg and sacrificed after seven days. There were no significant changes in dopamine or DOPAC concentrations in the neuroendocrine brain of males and females after treatment but GABA levels in females were moderately increased 20–30% in the hypothalamus and cerebellum. In the female hypothalamus, there were 227 transcripts (p<0.001) identified as being differentially regulated by dieldrin. Functional enrichment analysis revealed transcription, DNA repair, ubiquitin-proteasome pathway, and cell communication, as biological processes over-represented in the microarray analysis. Pathway analysis identified DNA damage, inflammation, regeneration, and Alzheimer’s disease as major cell processes and diseases affected by dieldrin. Using multiple bioinformatics approaches, this study demonstrates that the teleostean hypothalamus is a target for dieldrin-induced neurotoxicity and provides mechanistic evidence that dieldrin activates similar cell pathways and biological processes that are also associated with the etiology of human neurological disorders.

“…-48 mg/L) sont équivalentes aux CL = 1,1 à 41 mg/L chez les poissons, notamment chez Clarias gariepinus de 57 jours (11,7 mg/L) et chez Oreochromis niloticus de 57 jours (4,95 mg/ L)(Lamai et al, 1999). Résidus de pesticides organochlorés identifiés et quantifiés dans les sédiments collectés dans le lac Nokoué, le long du fleuve Ouémé et dans la rivière Agbado (mg/kg MO).…”

unclassified

Current status of the contamination of aquatic ecosystems by organochlorine pesticides in the cotton basin of Benin

Agbohessi¹,

Toko²,

Kestemont

2012

Cahiers Agricultures

État des lieux de la contamination des écosystèmes aquatiques par les pesticides organochlorés dans le Bassin cotonnier béninois Résumé Les pesticides organochlorés avaient été recommandés au Bénin dans les années 1960 (DDT, lindane, dieldrine, heptachlore, etc.) et de 1999 à 2007 (endosulfan) pour le contrôle des ravageurs du cotonnier. En dehors de ces périodes, l'utilisation illicite de certaines molécules de cette famille de pesticide a été signalée dans le bassin cotonnier. Les molécules d'organochlorés sont très lipophiles et très rémanentes. Par ailleurs, elles se dégradent rapidement sous l'action des rayons ultraviolets en des produits dérivés généralement plus toxiques et plus stables que les composés initiaux. Utilisés dans les champs, ces pesticides sont même retrouvés plusieurs années plus tard dans les écosystèmes aquatiques. Un travail de synthèse documentaire nous a permis de faire l'état des lieux de la contamination des biotopes aquatiques béninois par ces produits dangereux. Ainsi, des taux alarmants d'endosulfan, de DDT, de dieldrine et d'heptachlore ont été trouvés dans certaines eaux dont les eaux du parc W. Dans les sédiments à Bétérou, des taux élevés de DDT, d'endosulfan et de lindane ont été également mis en évidence. Des analyses sur des tilapias Sarotherodon melanotheron mâles capturés le long du fleuve Ouémé ont montré la présence de lindane, de dieldrine, d'heptachlore, de pp'-TDE ainsi qu'une concentration plasmatique élevée en vitellogénine. Des taux alarmants de DDT, d'endosulfan, de lindane et de dieldrine ont également été trouvés chez des polyptères Polypterus endlicheri capturés dans les eaux de la Pendjari.