Objective:To assess the molluscicidal and cercariacidal activities of aqueous extracts of Balanites aegyptiaca(B.aegyptiaca)against EthiopianBiomphalaria pfeifferi(B.pfeifferi),Lymnaea natalensis(L.natalensis)and Schi...Objective:To assess the molluscicidal and cercariacidal activities of aqueous extracts of Balanites aegyptiaca(B.aegyptiaca)against EthiopianBiomphalaria pfeifferi(B.pfeifferi),Lymnaea natalensis(L.natalensis)and Schistosoma mansoni(S.mansoni)cercariae.Methods:Extracts of seeds,endocarp,mesocarp,and fruit of B.aegyptiacawere tested for their activities against adultB.pfeifferiandL.natalensis.The cercariacidal activity of the seeds of the plant was also evaluated againstS.mansoni.Bioassays were carried out following the methods recommended by WHO.Snail mortalities were compared between each plant part and snail species,and LC50and LC90values for the plant parts tested were computed.The cercariacidal activity of the plant was assessed by exposing the mice to the cercariae pre-exposed to aqueous extract of B.aegyptiacaseeds.Results:For the molluscicidal activities of seeds,endocarp,mesocarp and whole fruit,the LC50values againstB.pfeifferiwere 56.32,77.53,65.51 and 66.63 mg/L,respectively,while the respective LC90values were 77.70,120.04,89.50 and 97.55 mg/L.Similarly,the LC50values for the seeds,endocarp,mesocarp and whole fruit againstL.natalensiswere 80.33,92.61,83.52 and 87.84mg/L,respectively,while the respective LC90values were 102.30,138.21,115.42 and 127.69 mg/L.B.pfeifferiwere found to be more susceptible toB.aegyptiacathanL.natalensis.S.mansoni cercariae exposed to 15 mg/L of extract of seeds were incapable of infecting mice.The mean egg load of tissue was reduced in mice infected with the cercariae exposed to 5 and 10 mg/L of the extract.Conclusions:The aqueous extracts of different parts ofB.aegyptiacaexhibited reasonable molluscicidal activity againstB.pfeifferiandL.natalensis,as well as cercariacidal activity againstS.mansonicercariae.However,comprehensive laboratory evaluation is recommended prior to field tests of the plant parts since their impact on other aquatic biota is not known.展开更多
Environmental warming places physiological constraints on organisms, which may be mitigated by their feeding behavior. Theory predicts that consumers should increase their feeding selectivity for more energetically va...Environmental warming places physiological constraints on organisms, which may be mitigated by their feeding behavior. Theory predicts that consumers should increase their feeding selectivity for more energetically valuable resources in warmer environments to offset the disproportionate increase in metabolic demand relative to ingestion rate. This may also result in a change in feeding strategy or a shift towards a more specialist diet. This study used a natural warming experiment to investigate temperature effects on the feeding selectivity of three freshwater invertebrate grazers： the snail Radix balthica, the blackfly larva Simulium aureum, and the midgefly larva Eukiefferiella minor. Chesson＇s Selectivity Index was used to compare the proportional abundance of diatom species in the guts of each invertebrate species with corresponding rock biofilms sampled from streams of different tem- perature. The snails became more selective in warmer streams, choosing high profile epilithic diatoms over other guilds and feeding on a lower diversity of diatom species. The blackfly larvae appeared to switch from active collector gathering of sessile high profile diatoms to more passive filter feeding of motile diatoms in warmer streams. No changes in selectivity were observed for the midgefly larvae, whose diet was representative of resource availability in the environment. These results suggest that key primary consumers in freshwater streams, which constitute a major portion of invertebrate biomass, can change their feeding behavior in warmer waters in a range of different ways. These patterns could potentially lead to fundamental changes in the flow of energy through freshwater food webs.展开更多
Animals exhibit remarkable behavioral and molecular adaptations to cope with thermal stressors,which are crucial for survival in variable environments that are exacerbated by climate change.Aquatic poikilotherms like ...Animals exhibit remarkable behavioral and molecular adaptations to cope with thermal stressors,which are crucial for survival in variable environments that are exacerbated by climate change.Aquatic poikilotherms like our model organism-the pond snail Lymnaea stagnalis--face significant challenges due to their dependence on external temperatures.Our study provides valuable insights into the different behavioral and molecular responses of lab-inbred snails to cold and heat shock stressors(i.e.,4℃ and 30℃),particularly in the context of learning and memory formation.We found that while short-term(1 h)cold exposure transiently upregulated the expression levels of HSP70 and HSP40 in the snail's central ring ganglia,prolonged cold exposure(24 h)resulted in a significant downregulation of LymMIPII and an upregulation of LymMIPR.These data suggest,albeit at the transcriptional level,the existence of a negative feedback loop necessary for sustaining cellullar functions when metabolic demands might shift towards conserving energy during prolonged cold exposure.At the behavioral level,we found that,compared to heat shock,cold exposure did not result in a Garcia effect(i.e.,a“special form"of conditioned taste aversion).The difference in memory outcomes was associated with changes in the expression levels of selected targets involved in neuronal plasticity and the stress response.While both cold and heat shock upregulated the HSP levels in the snail's central ring ganglia,cold exposure did not affect the expression levels of the neuroplasticity genes LymGRIN1 and LymCREB1,contrasting with heat shock's neurogenic effects.Overall,this study provides insights into L.stagnalis's adaptive responses to thermal stressors,emphasizing different molecular strategies for coping with heat versus cold challenges in aquatic environments.These findings contribute to our understanding of thermal biology and stress physiology in aquatic organisms,underscoring the importance of molecular mechanisms in shaping species'resilience in dynamic environments.展开更多
基金Financially supported by School of Graduate Studies,Addis Ababa University(Grant No.GSR/2830/02)
文摘Objective:To assess the molluscicidal and cercariacidal activities of aqueous extracts of Balanites aegyptiaca(B.aegyptiaca)against EthiopianBiomphalaria pfeifferi(B.pfeifferi),Lymnaea natalensis(L.natalensis)and Schistosoma mansoni(S.mansoni)cercariae.Methods:Extracts of seeds,endocarp,mesocarp,and fruit of B.aegyptiacawere tested for their activities against adultB.pfeifferiandL.natalensis.The cercariacidal activity of the seeds of the plant was also evaluated againstS.mansoni.Bioassays were carried out following the methods recommended by WHO.Snail mortalities were compared between each plant part and snail species,and LC50and LC90values for the plant parts tested were computed.The cercariacidal activity of the plant was assessed by exposing the mice to the cercariae pre-exposed to aqueous extract of B.aegyptiacaseeds.Results:For the molluscicidal activities of seeds,endocarp,mesocarp and whole fruit,the LC50values againstB.pfeifferiwere 56.32,77.53,65.51 and 66.63 mg/L,respectively,while the respective LC90values were 77.70,120.04,89.50 and 97.55 mg/L.Similarly,the LC50values for the seeds,endocarp,mesocarp and whole fruit againstL.natalensiswere 80.33,92.61,83.52 and 87.84mg/L,respectively,while the respective LC90values were 102.30,138.21,115.42 and 127.69 mg/L.B.pfeifferiwere found to be more susceptible toB.aegyptiacathanL.natalensis.S.mansoni cercariae exposed to 15 mg/L of extract of seeds were incapable of infecting mice.The mean egg load of tissue was reduced in mice infected with the cercariae exposed to 5 and 10 mg/L of the extract.Conclusions:The aqueous extracts of different parts ofB.aegyptiacaexhibited reasonable molluscicidal activity againstB.pfeifferiandL.natalensis,as well as cercariacidal activity againstS.mansonicercariae.However,comprehensive laboratory evaluation is recommended prior to field tests of the plant parts since their impact on other aquatic biota is not known.
文摘Environmental warming places physiological constraints on organisms, which may be mitigated by their feeding behavior. Theory predicts that consumers should increase their feeding selectivity for more energetically valuable resources in warmer environments to offset the disproportionate increase in metabolic demand relative to ingestion rate. This may also result in a change in feeding strategy or a shift towards a more specialist diet. This study used a natural warming experiment to investigate temperature effects on the feeding selectivity of three freshwater invertebrate grazers： the snail Radix balthica, the blackfly larva Simulium aureum, and the midgefly larva Eukiefferiella minor. Chesson＇s Selectivity Index was used to compare the proportional abundance of diatom species in the guts of each invertebrate species with corresponding rock biofilms sampled from streams of different tem- perature. The snails became more selective in warmer streams, choosing high profile epilithic diatoms over other guilds and feeding on a lower diversity of diatom species. The blackfly larvae appeared to switch from active collector gathering of sessile high profile diatoms to more passive filter feeding of motile diatoms in warmer streams. No changes in selectivity were observed for the midgefly larvae, whose diet was representative of resource availability in the environment. These results suggest that key primary consumers in freshwater streams, which constitute a major portion of invertebrate biomass, can change their feeding behavior in warmer waters in a range of different ways. These patterns could potentially lead to fundamental changes in the flow of energy through freshwater food webs.
基金funded by Regione Emilia Romagna L.R.N.20/2002 PROGETTI DI RICERCA SUI METODI ALTERNATIVE ALL’UTILIZZO DI ANIMALIFAR 2016 Department of Life Sciences,University of Modena and Reggio Emilia,and the Natural Sciences and Engineering Research Council of Canada.
文摘Animals exhibit remarkable behavioral and molecular adaptations to cope with thermal stressors,which are crucial for survival in variable environments that are exacerbated by climate change.Aquatic poikilotherms like our model organism-the pond snail Lymnaea stagnalis--face significant challenges due to their dependence on external temperatures.Our study provides valuable insights into the different behavioral and molecular responses of lab-inbred snails to cold and heat shock stressors(i.e.,4℃ and 30℃),particularly in the context of learning and memory formation.We found that while short-term(1 h)cold exposure transiently upregulated the expression levels of HSP70 and HSP40 in the snail's central ring ganglia,prolonged cold exposure(24 h)resulted in a significant downregulation of LymMIPII and an upregulation of LymMIPR.These data suggest,albeit at the transcriptional level,the existence of a negative feedback loop necessary for sustaining cellullar functions when metabolic demands might shift towards conserving energy during prolonged cold exposure.At the behavioral level,we found that,compared to heat shock,cold exposure did not result in a Garcia effect(i.e.,a“special form"of conditioned taste aversion).The difference in memory outcomes was associated with changes in the expression levels of selected targets involved in neuronal plasticity and the stress response.While both cold and heat shock upregulated the HSP levels in the snail's central ring ganglia,cold exposure did not affect the expression levels of the neuroplasticity genes LymGRIN1 and LymCREB1,contrasting with heat shock's neurogenic effects.Overall,this study provides insights into L.stagnalis's adaptive responses to thermal stressors,emphasizing different molecular strategies for coping with heat versus cold challenges in aquatic environments.These findings contribute to our understanding of thermal biology and stress physiology in aquatic organisms,underscoring the importance of molecular mechanisms in shaping species'resilience in dynamic environments.
