RESUMO
BACKGROUND: Cladocera is an important group of freshwater zooplankton, and the species plays an important role in energy transfer and in aquatic food webs. Oxyurella longicaudis is a Chydoridae species that has been recorded in North and South America. The aim of this study is to investigate the life cycle aspects of parthenogenetic females of O. longicaudis cultured in laboratory under controlled conditions: temperature (23°C ± 05°C), photoperiod (12 h light/12 h dark), food supply, and reconstituted water. RESULTS: Embryonic development duration (2.3 ± 0.5 days), post-embryonic development (5.2 ± 0.69 days), mean fecundity (two eggs female-1 brood-1), total egg production (22.55 ± 3.98 eggs), average longevity (58 days), and body growth of the species were recorded. We also report the first DNA barcode for O. longicaudis isolated in Brazil, which will allow for easy identification in future zooplankton community studies. The analysis shows a genetic divergence of around 7% between our Brazilian isolate and O. longicaudisisolates from Mexico. CONCLUSIONS: The time of embryonic and post-embryonic development of O. longicaudis was higher than that of the other species of the same family, which contributed to lower total egg production throughout its life cycle. The genetic divergence appears to be sufficient to classify the two isolates as different species.
RESUMO
Knowledge of reproductive rates and life cycle of the Cladocera species is essential for population dynamic studies, secondary production and food webs, as well as the management and preservation of aquatic ecosystems. The present study aimed to understand the life cycle and growth of Alona iheringula Kotov & Sinev, 2004 (Crustacea, Anomopoda, Chydoridae), a Neotropical species, as well as its DNA barcoding, providing new information on the Aloninae taxonomy. The specimens were collected in the dammed portion of the Cabo Verde River (21°26'05â³ S and 46°10'57â³ W), in the Furnas Reservoir, Minas Gerais State, Brazil. Forty neonates were observed individually two or three times a day under controlled temperature (25±1°C), photoperiod (12 h light/12 h dark) and feeding (Pseudokirchneriella subcapitata at a concentration of 105 cells.mL-1 and a mixed suspension of yeast and fish feed in equal proportion). Individual body growth was measured daily under optical microscope using a micrometric grid and 40× magnification. The species had a mean size of 413(±29) µm, a maximum size of 510 µm and reached maturity at 3.24(±0.69) days of age. Mean fecundity was 2 eggs per female per brood and the mean number of eggs produced per female during the entire life cycle was 47.6(±6.3) eggs per female. The embryonic development time was 1.79(±0.23) days and the maximum longevity was 54 days. The species had eight instars throughout its life cycle and four instars between neonate and primipara stage. The present study using molecular data (a 461 bp smaller COI fragment) demonstrated a deep divergence in the Aloninae subfamily.
Assuntos
Cladocera/classificação , Cladocera/crescimento & desenvolvimento , Código de Barras de DNA Taxonômico , Estágios do Ciclo de Vida , Animais , Biodiversidade , Cladocera/enzimologia , Cladocera/genética , Complexo IV da Cadeia de Transporte de Elétrons/genética , FemininoRESUMO
Species of Chydoridae provide the main diversity of the Cladocera. These organisms have been the subject of many studies; some dealing with their role in energy flow in aquatic ecosystems, since they inhabit the littoral region of water bodies which undergo the first impacts from anthropic activities. The aim of this study is to increase knowledge about the life cycle of Coronatella rectangula (Sars, 1861), a species found in several water bodies in the state of Minas Gerais, Brazil. The life cycle was determined by the culture of parthenogenetic females under controlled conditions in the laboratory. Experimental cultures were maintained in growth chambers at a constant temperature of 23.6(±0.5)ºC, through a 12 h light/12 h dark photoperiod. The organisms were fed on a suspension of Pseudokirchneriella subcapitata (Chlorophyceae) (10(5) cells.mL⁻¹), and 0.02 mL of a mixed suspension of yeast and fish ration added per organism in equal proportions (1:1). Fifty parthenogenetic females with eggs were isolated and maintained until they produced neonates. Thirty of these neonates that had less than 24 hours were put in polypropylene bottles of 50 mL and kept in a germination chamber. These organisms were observed daily to obtain the parameters of the life cycle. Biomass and secondary production were also calculated. The embryonic development time of the specimens of C. rectangula was 1.68(±0.13) days and the time to reach primipara, was 2.48(±0.45) days. The mean fecundity of C. rectangula was two eggs/female/brood and the total number of eggs produced by the female during its life cycle was 27.8 eggs. During the whole life cycle, specimens of C. rectangula had a maximum of 14 seedlings, with two instars in the juvenile stage
As espécies de Chydoridae correspondem a maior diversidade de Cladocera. Estes organismos tem sido objeto de diversos estudos, com enfoque para seu papel no fluxo de energia nos ambientes aquáticos, uma vez que habitam a região litoral dos corpos d'água que recebem os primeiros impactos decorrentes das atividades antrópicas. O objetivo deste estudo é conhecer o ciclo de vida de Coronatella rectangula (Sars, 1861), espécie encontrada em vários corpos d'água de Minas Gerais, Brasil. O ciclo de vida foi determinado através do cultivo em laboratório de fêmeas partenogenéticas, sob condições controladas. Culturas experimentais foram mantidas em câmaras de germinação com temperatura de 23,6(±0,5)ºC e fotoperíodo constante (12h claro/12h escuro). Os organismos foram alimentados com uma suspensão de 10(5) células.mL⁻¹ da clorofícea Pseudokirchneriella subcapitata e 0,02 mL de uma suspensão mista de levedura e ração de peixe em igual proporção (1:1). Cinquenta fêmeas com ovos foram isoladas e mantidas até a produção de neonatas. Trinta neonatas com menos de 24 horas foram colocadas em potes de 50 mL de polipropileno e conservadas em câmara de germinação. Estes organismos foram observados diariamente para obtenção dos parâmetros do ciclo de vida. Foram calculadas também a biomassa e a produção secundária. O tempo de desenvolvimento embrionário dos espécimes de C. rectangula foi de 1,68 (±0,13) dias e a idade da primípara (tempo de desenvolvimento pós- embrionário) foi de 2,48 (±0,45) dias. A fecundidade média foi de 2 ovos/fêmea/ninhada e o número total de ovos produzidos durante todo o ciclo de vida foi de 27,8 ovos. Durante todo o ciclo de vida, espécimes de C. rectangula tiveram um máximo de 14 mudas, sendo dois ínstares no estágio juvenil...
Assuntos
Animais , Biomassa , Cladocera , Crustáceos/crescimento & desenvolvimento , Características de História de VidaRESUMO
Species of Chydoridae provide the main diversity of the Cladocera. These organisms have been the subject of many studies; some dealing with their role in energy flow in aquatic ecosystems, since they inhabit the littoral region of water bodies which undergo the first impacts from anthropic activities. The aim of this study is to increase knowledge about the life cycle of Coronatella rectangula (Sars, 1861), a species found in several water bodies in the state of Minas Gerais, Brazil. The life cycle was determined by the culture of parthenogenetic females under controlled conditions in the laboratory. Experimental cultures were maintained in growth chambers at a constant temperature of 23.6(±0.5)ºC, through a 12 h light/12 h dark photoperiod. The organisms were fed on a suspension of Pseudokirchneriella subcapitata (Chlorophyceae) (10(5) cells.mL⁻¹), and 0.02 mL of a mixed suspension of yeast and fish ration added per organism in equal proportions (1:1). Fifty parthenogenetic females with eggs were isolated and maintained until they produced neonates. Thirty of these neonates that had less than 24 hours were put in polypropylene bottles of 50 mL and kept in a germination chamber. These organisms were observed daily to obtain the parameters of the life cycle. Biomass and secondary production were also calculated. The embryonic development time of the specimens of C. rectangula was 1.68(±0.13) days and the time to reach primipara, was 2.48(±0.45) days. The mean fecundity of C. rectangula was two eggs/female/brood and the total number of eggs produced by the female during its life cycle was 27.8 eggs. During the whole life cycle, specimens of C. rectangula had a maximum of 14 seedlings, with two instars in the juvenile stage (AU)
As espécies de Chydoridae correspondem a maior diversidade de Cladocera. Estes organismos tem sido objeto de diversos estudos, com enfoque para seu papel no fluxo de energia nos ambientes aquáticos, uma vez que habitam a região litoral dos corpos d'água que recebem os primeiros impactos decorrentes das atividades antrópicas. O objetivo deste estudo é conhecer o ciclo de vida de Coronatella rectangula (Sars, 1861), espécie encontrada em vários corpos d'água de Minas Gerais, Brasil. O ciclo de vida foi determinado através do cultivo em laboratório de fêmeas partenogenéticas, sob condições controladas. Culturas experimentais foram mantidas em câmaras de germinação com temperatura de 23,6(±0,5)ºC e fotoperíodo constante (12h claro/12h escuro). Os organismos foram alimentados com uma suspensão de 10(5) células.mL⁻¹ da clorofícea Pseudokirchneriella subcapitata e 0,02 mL de uma suspensão mista de levedura e ração de peixe em igual proporção (1:1). Cinquenta fêmeas com ovos foram isoladas e mantidas até a produção de neonatas. Trinta neonatas com menos de 24 horas foram colocadas em potes de 50 mL de polipropileno e conservadas em câmara de germinação. Estes organismos foram observados diariamente para obtenção dos parâmetros do ciclo de vida. Foram calculadas também a biomassa e a produção secundária. O tempo de desenvolvimento embrionário dos espécimes de C. rectangula foi de 1,68 (±0,13) dias e a idade da primípara (tempo de desenvolvimento pós- embrionário) foi de 2,48 (±0,45) dias. A fecundidade média foi de 2 ovos/fêmea/ninhada e o número total de ovos produzidos durante todo o ciclo de vida foi de 27,8 ovos. Durante todo o ciclo de vida, espécimes de C. rectangula tiveram um máximo de 14 mudas, sendo dois ínstares no estágio juvenil...(AU)
Assuntos
Animais , Crustáceos/crescimento & desenvolvimento , Características de História de Vida , Biomassa , CladoceraRESUMO
Leishmania (Sauroleishmania) tarentolae has biotechnological potential for use as live vaccine against visceral leishmaniasis and as a system for the over expression of eukaryotic proteins that possess accurate post-translational modifications. For both purposes, new systems for protein expression in this non-pathogenic protozoan are necessary. The ribosomal RNA promoter proved to be a stronger transcription driver since its use yielded increased levels of recombinant protein in organisms of both genera Trypanosoma or Leishmania. We have evaluated heterologous expression systems using vectors with two different polypyrimidine tracts in the splice acceptor site by measuring a reporter gene transcribed from L. tarentolae RNA polymerase I promoter. Our data indicate that the efficiency of chloramphenicol acetyl transferase expression changed drastically with homologous or heterologous sequences, depending on the polypyrimidine tract used in the construct and differences in size and/or distance from the AG dinucleotide. In relation to the promoter sequence the reporter expression was higher in heterologous lizard-infecting species than in the homologous L. tarentolae or in the mammalian-infecting L. (Leishmania) amazonensis.
Assuntos
Leishmania/genética , Regiões Promotoras Genéticas/genética , RNA Polimerase I/genética , Sítios de Splice de RNA/genética , Animais , Expressão Gênica , Leishmania/classificaçãoRESUMO
Leishmania (Sauroleishmania) tarentolae has biotechnological potential for use as live vaccine against visceral leishmaniasis and as a system for the over expression of eukaryotic proteins that possess accurate post-translational modifications. For both purposes, new systems for protein expression in this non-pathogenic protozoan are necessary. The ribosomal RNA promoter proved to be a stronger transcription driver since its use yielded increased levels of recombinant protein in organisms of both genera Trypanosoma or Leishmania. We have evaluated heterologous expression systems using vectors with two different polypyrimidine tracts in the splice acceptor site by measuring a reporter gene transcribed from L. tarentolae RNA polymerase I promoter. Our data indicate that the efficiency of chloramphenicol acetyl transferase expression changed drastically with homologous or heterologous sequences, depending on the polypyrimidine tract used in the construct and differences in size and/or distance from the AG dinucleotide. In relation to the promoter sequence the reporter expression was higher in heterologous lizard-infecting species than in the homologous L. tarentolae or in the mammalian-infecting L. (Leishmania) amazonensis.