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Doctoral Thesis
DOI
https://doi.org/10.11606/T.11.2001.tde-20210104-201651
Document
Author
Full name
Fagoni Fayer Calegario
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
Piracicaba, 2001
Supervisor
Title in Portuguese
Ativação de proteína mitocondrial desacopladora e oxidase alternativa em tubérculos de batata armazenados sob refrigeração
Keywords in Portuguese
ARMAZENAMENTO
BATATA
MITOCÔNDRIAS
OXIDASE
PROTEÍNAS
REFRIGERAÇÃO
RESPIRAÇÃO VEGETAL
Abstract in Portuguese
Uma proteína mitocondrial desacopladora de plantas (PUMP), possivelmente envolvida em produção de calor em vegetais, foi isolada, reconstituída em lipossomos e clonada (Vercesi et al., 1995; Maia et al., 1998). Com o objetivo de investigar um possível papel termogênico da PUMP em tecidos intactos, avaliamos a atividade respiratória de tubérculos de batata (Solanum tuberosum L., cv. Bintje) inteiros armazenados por dez dias a 5±1°C e 25±2°C. Essas taxas foram comparadas com a atividade e expressão da PUMP e com a capacidade da proteína oxidase alternativa (AOX) em mitocôndrias isoladas destes tecidos. Um sistema de análise em fluxo acoplado a um detetor condutométrico de CO2 foi construído visando medir a taxa respiratória de tubérculos inteiros. O método foi testado utilizando-se frutos do tomateiro e mostrou-se capaz de fornecer resultados precisos, a baixo custo. A taxa de produção de CO2, medida a 20°C, nos tubérculos de batata caiu rapidamente de 13 a 8 mg kg-1 h-1 durante os dois primeiros dias de armazenamento a 25±2°C e diminuiu lentamente de 8 a 6,5 mg kg-1 h-1 durante os 7 dias seguintes. Em contraste, a evolução de CO2 das batatas armazenadas a 5±1°C não se alterou significativamente no primeiro dia, subiu para 14,5 mg kg-1 h-1 durante os 2 dias seguintes e então diminuiu para cerca de 12 mg kg-1 h-1 nos 7 dias seguintes. A atividade respiratória mais alta dos tubérculos intactos armazenados a 5±1°C foi associada a um aumento na expressão da PUMP, evidenciado na imunodetecção desta proteína, e a aumentos de 44% na atividade da PUMP e de cerca de dez vezes na capacidade da AOX, estimados pelo consumo de oxigênio mitocondrial. Conclui-se que a refrigeração causou aumento da taxa respiratória em tubérculos inteiros associado a aumentos na atividade e expressão da PUMP e na capacidade da AOX em mitocôndrias isoladas.
Title in English
Activation of uncoupling mitochondrial protein and alternative oxidase in potato tubers stored under refrigeration
Keywords in English

Abstract in English
A plant uncoupling mitochondrial protein (PUMP), possibly involved in heat generation in plants, was isolated, reconstituted into liposomes, and cloned (Vercesi et al., 1995; Maia et al., 1998). ln order to investigate a possible thermogenic role of PUMP in intact tissues, we evaluated the respiratory activity in intact potato (Solanum tuberosum L., cv. Bintje) tubers stored for 10 days at 5±1°C and 25±2°C. These respiration rates were compared with PUMP activity and expression and with the capacity of the alternative oxidase protein (AOX) in mitochondria isolated from these tissues. A flow analysis system coupled to a conductometric CO2 detector was built in order to measure the respiration rate of intact potato tubers. The method was tested using tomato fruit and showed to be reliable to supply precise results, at a low cost. The rate of CO2 production by potato tubers, measured at 20°C, sharply declined from 13.0 to 8.0 mg kg-1 h-1 during the first two days of storage at 25±2°C and decreased slowly from 8.0 to 6.5 mg kg-1 h-1 during the following 7 days. ln contrast, CO2 evolution from potatoes stored at 5±1°C did not significantly change during the first day, increased up to 14.5 mg kg-1 h-1 during the following 2 days and then decreased to about 12.0 mg kg-1 h-1 in the following 7 days. The higher respiratory activity of the intact tubers stored at 5±1°C was associated with an increased expression of PUMP, shown by the immunodetection of this protein, and with a 44% increase in the activity of PUMP and a 10 times increase in the capacity of the AOX, estimated by O2 consumption by mitochondria. In conclusion, refrigeration caused an increase of the respiration rate of the intact potatoes associated with increase in PUMP activity and expression, and with increase in the AOX capacity in mitochondria isolated.
 
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Publishing Date
2021-01-07
 
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