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Maintenance Energy Requirements (maintenance + energy_requirement)

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Life Sciences100%

Selected Abstracts

Large-scale distribution and activity patterns of an extremely low-light-adapted population of green sulfur bacteria in the Black Sea

ENVIRONMENTAL MICROBIOLOGY, Issue 5 2010
Evelyn Marschall
Summary The Black Sea chemocline represents the largest extant habitat of anoxygenic phototrophic bacteria and harbours a monospecific population of Chlorobium phylotype BS-1. High-sensitivity measurements of underwater irradiance and sulfide revealed that the optical properties of the overlying water column were similar across the Black Sea basin, whereas the vertical profiles of sulfide varied strongly between sampling sites and caused a dome-shaped three-dimensional distribution of the green sulfur bacteria. In the centres of the western and eastern basins the population of BS-1 reached upward to depths of 80 and 95 m, respectively, but were detected only at 145 m depth close to the shelf. Using highly concentrated chemocline samples from the centres of the western and eastern basins, the cells were found to be capable of anoxygenic photosynthesis under in situ light conditions and exhibited a photosynthesis,irradiance curve similar to low-light-adapted laboratory cultures of Chlorobium BS-1. Application of a highly specific RT-qPCR method which targets the internal transcribed spacer (ITS) region of the rrn operon of BS-1 demonstrated that only cells at the central station are physiologically active in contrast to those at the Black Sea periphery. Based on the detection of ITS-DNA sequences in the flocculent surface layer of deep-sea sediments across the Black Sea, the population of BS-1 has occupied the major part of the basin for the last decade. The continued presence of intact but non-growing BS-1 cells at the periphery of the Black Sea indicates that the cells can survive long-distant transport and exhibit unusually low maintenance energy requirements. According to laboratory measurements, Chlorobium BS-1 has a maintenance energy requirement of ,1.6,4.9·10,15 kJ cell,1 day,1 which is the lowest value determined for any bacterial culture so far. Chlorobium BS-1 thus is particularly well adapted to survival under the extreme low-light conditions of the Black Sea, and can be used as a laboratory model to elucidate general cellular mechanisms of long-term starvation survival. Because of its adaptation to extreme low-light marine environments, Chlorobium BS-1 also represents a suitable indicator for palaeoceanography studies of deep photic zone anoxia in ancient oceans. [source]

The effect of weight loss by energy restriction on metabolic profile and glucose tolerance in ponies

JOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 5 2008
S. Van Weyenberg
Summary In nine initially obese ponies, a weekly weight loss according to 1% of their ideal body weight was evaluated for its impact on insulin sensitivity and metabolic profile. Weight loss was obtained solely through energy restriction, initially at 70% of maintenance energy requirements, but to maintain constant weight loss, feed amount had to be decreased to 50% and 35% of maintenance energy requirement during the course of the trial. An oral glucose tolerance test (OGTT) was performed at weeks 0, 10 and 17. Fasted blood samples were taken on weeks 0, 3, 10, 17 for analysis of triglycerides (TG), non-esterified fatty acids (NEFA), creatine phosphokinase (CPK), lactate dehydrogenase (LDH), T3, T4 and leptin. Total average weight loss was 18.2%. When the OGTT was performed at weeks 0, 10 and 17, ponies had lost 0.22%, 9.9% and 16.3% of their initial weight respectively. Weight loss was associated with a decreased AUC for glucose and insulin. Moreover, greater % weight loss was associated with a significantly lower glucose peak and a lower area under the curve (AUC glucose). The lower glucose response after an OGTT in lean ponies was not the result of an increased insulin secretion, but an improved insulin sensitivity. Restricted feeding led to mobilization of TG and NEFA and to a reduced basal metabolism, with lower LDH, CPK, T3 and leptin. In conclusion: in obese Shetland ponies, weight loss at a rate of 1% of ideal body weight per week through restricted energy intake, ameliorated insulin sensitivity. [source]

Large-scale distribution and activity patterns of an extremely low-light-adapted population of green sulfur bacteria in the Black Sea

ENVIRONMENTAL MICROBIOLOGY, Issue 5 2010
Evelyn Marschall
Summary The Black Sea chemocline represents the largest extant habitat of anoxygenic phototrophic bacteria and harbours a monospecific population of Chlorobium phylotype BS-1. High-sensitivity measurements of underwater irradiance and sulfide revealed that the optical properties of the overlying water column were similar across the Black Sea basin, whereas the vertical profiles of sulfide varied strongly between sampling sites and caused a dome-shaped three-dimensional distribution of the green sulfur bacteria. In the centres of the western and eastern basins the population of BS-1 reached upward to depths of 80 and 95 m, respectively, but were detected only at 145 m depth close to the shelf. Using highly concentrated chemocline samples from the centres of the western and eastern basins, the cells were found to be capable of anoxygenic photosynthesis under in situ light conditions and exhibited a photosynthesis,irradiance curve similar to low-light-adapted laboratory cultures of Chlorobium BS-1. Application of a highly specific RT-qPCR method which targets the internal transcribed spacer (ITS) region of the rrn operon of BS-1 demonstrated that only cells at the central station are physiologically active in contrast to those at the Black Sea periphery. Based on the detection of ITS-DNA sequences in the flocculent surface layer of deep-sea sediments across the Black Sea, the population of BS-1 has occupied the major part of the basin for the last decade. The continued presence of intact but non-growing BS-1 cells at the periphery of the Black Sea indicates that the cells can survive long-distant transport and exhibit unusually low maintenance energy requirements. According to laboratory measurements, Chlorobium BS-1 has a maintenance energy requirement of ,1.6,4.9·10,15 kJ cell,1 day,1 which is the lowest value determined for any bacterial culture so far. Chlorobium BS-1 thus is particularly well adapted to survival under the extreme low-light conditions of the Black Sea, and can be used as a laboratory model to elucidate general cellular mechanisms of long-term starvation survival. Because of its adaptation to extreme low-light marine environments, Chlorobium BS-1 also represents a suitable indicator for palaeoceanography studies of deep photic zone anoxia in ancient oceans. [source]

The effect of weight loss by energy restriction on metabolic profile and glucose tolerance in ponies

JOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 5 2008
S. Van Weyenberg
Summary In nine initially obese ponies, a weekly weight loss according to 1% of their ideal body weight was evaluated for its impact on insulin sensitivity and metabolic profile. Weight loss was obtained solely through energy restriction, initially at 70% of maintenance energy requirements, but to maintain constant weight loss, feed amount had to be decreased to 50% and 35% of maintenance energy requirement during the course of the trial. An oral glucose tolerance test (OGTT) was performed at weeks 0, 10 and 17. Fasted blood samples were taken on weeks 0, 3, 10, 17 for analysis of triglycerides (TG), non-esterified fatty acids (NEFA), creatine phosphokinase (CPK), lactate dehydrogenase (LDH), T3, T4 and leptin. Total average weight loss was 18.2%. When the OGTT was performed at weeks 0, 10 and 17, ponies had lost 0.22%, 9.9% and 16.3% of their initial weight respectively. Weight loss was associated with a decreased AUC for glucose and insulin. Moreover, greater % weight loss was associated with a significantly lower glucose peak and a lower area under the curve (AUC glucose). The lower glucose response after an OGTT in lean ponies was not the result of an increased insulin secretion, but an improved insulin sensitivity. Restricted feeding led to mobilization of TG and NEFA and to a reduced basal metabolism, with lower LDH, CPK, T3 and leptin. In conclusion: in obese Shetland ponies, weight loss at a rate of 1% of ideal body weight per week through restricted energy intake, ameliorated insulin sensitivity. [source]

Metabolic changes during the perinatal period in dairy sheep in relation to level of nutrition and breed.

JOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 3-4 2000

Summary The effect of level of nutrition during pregnancy was investigated on various plasma parameters, on energy intake, body weight, energy balance and milk yield, after parturition in two Greek dairy breeds. Thirteen Chios (CH) and 17 Karagouniko (K) pregnant ewes were assigned to groups A and B, which received 110% of their energy requirements for maintenance plus pregnancy for two foetuses and 90% of their maintenance energy requirements, respectively. After parturition all ewes were fed ad libitum. Body weights of group A and K ewes were higher (p 0.05) compared with group B and CH ewes, during lactation, although daily energy intakes tended to be greater in group B than in A ewes, during the first 3 weeks and in CH than K ewes (p 0.05), after the second week post-partum. Total mean milk production was 114 ± 11 l and 82 ± 10 l for groups A and B (p 0.05) and 120 ± 12 l and 70 ± 7 l for CH and K ewes (p 0.001), respectively. Positive energy balance appeared after the day 15 and 7 of lactation, for groups A and B ewes and after the day 15 and 5 of lactation, for CH and K ewes, respectively. The group B and K ewes tended to have higher mean plasma glucose concentrations than group A and CH ewes, during early lactation. There were no significant differences in free fatty acids, ,-hydroxybutyric acid, insulin and T4 concentrations between A and B ewes. CH had higher free fatty acids (p 0.05) and ,-hydroxybutyric acid (p 0.05), and lower T4 (p 0.01) and insulin (p 0.05) concentrations than K ewes. It was concluded that under-nutrition during pregnancy results in low milk yields of ewes fed ad libitum in early lactation, due to the poor development of the udder during late gestation. [source]