Body weight,metabolic rate,and trace substance turnover in animals

Summary Consequences of size-dependent metabolic rate on the turnover of trace substances in animals are investigated. At steady state, the biological half-life, body burden, and whole body concentration of a trace substance are shown to be proportional to body weight raised to (1-b), 1, and 0, respectively, where b is the exponent relating body weight to standard metabolic rate. The condition is that the trace substance is turned over in proportion to the standard metabolic rate; the derived equations can accordingly be used to test whether a given substance is feasible as a tracer of energy flow in ecologic systems.     

Body weight and metabolic level in growing chickens

Body weight and metabolic level in growing chickens. Acta Physiol. Pol., 1977, 28 (6): 575-583. In the investigations carried out on 128 White Rock chicken the metabolic level was determined under standard conditions in chickens characterising by different growth rate resulted from different feeding levels. It was shown that the feeding level of growing chicken has an essential influence on the character of the regression between the metabolic level and body weight. It was also found that this regression is not necessarily ot the character of Kleiber's function H = aWb. The differences in the metabolic level between the chickens maintained on different feeding levels did not disappear even after 4 days of starvation. In the light of the obtained results and recent investigations by other authors the usefulness of the so-called metabolic unit of the body size based on W0.75 in context to growing animals within one species has bee criticized.     

植物干旱胁迫下水分代谢、碳饥饿与死亡机理

植物在生长发育过程中受众多环境因子共同作用。随着全球气候变化,气温升高、降水量下降等问题频繁出现。目前气象学家一致预测未来环境变暖会使干旱更加频繁剧烈,这一环境改变使植物死亡更加严重。植物在水分胁迫、特别是干旱胁迫条件下,体内水分代谢与碳代谢会发生失衡现象:光合速率降低、蒸腾速率降低,带来生长降低;为维持植物新陈代谢,植物呼吸作用必然下调。在长期干旱胁迫条件下植物体内碳水化合物储存发生失衡现象,这种失衡使植物陷入碳饥饿现象。另外,由于水分失衡而出现的木质部栓塞和空穴会进一步加剧水分运输障碍,而修复空穴则需要大量非结构性碳水化合物(NSC),这使植物陷入两难选择。总结了植物干旱胁迫下,碳饥饿与水分代谢、植物死亡关系的相关研究,对未来的研究方向和重点提出建议,以期对未来的植物死亡研究提供帮助。     

Possible metabolic constraints on human brain weight at birth

Having humans born with adult-size brains would entail only a small and readily evolved increase in the size of the human female birth canal. The explanation for the present size of the human brain at birth is then plausibly based on the upper limit of brain that can be nourished by present human nutritional strategies. This limit turns out to be about 10% of the body weight of the newborn infant, in agreement with the actual value.     

Body weight and tissue composition in rats made obese by a cafeteria diet. Effect of 24 hours starvation

Rat body size and tissue composition changes from pre-weaning to three months age resulted from voluntary hyperphagia triggered by offering a cafeteria diet. The effects of a 24 hour starvation period in both cafeteria and chow fed controls were compared. Obesity develops earlier in females than in males. This difference is related to the growth patterns in both sexes. Obesity occurs at the stages of development when growth rate decreases. Cafeteria fed female rats attained a 32% greater weight than their controls, with lumbar adipose cords that were 4 times heavier and brown interscapular adipose tissue 2 times heavier than controls. The overall cafeteria fed versus chow fed rat differences in the effects of a 24 hour starvation, were minor but less liver glycogen and much more skeletal muscle lipids were mobilized in the cafeteria fed rats than in controls.     

Physiological and metabolic adjustments of Hoplosternum littorale (Teleostei,Callichthyidae) during starvation

All animals face the possibility of limitations in food resources that could ultimately lead to mortality caused by starvation. The primary goal of this study was to characterize the various physiological strategies that allow fish to survive starvation. A multiparametric approach, including morphological biomarkers, blood plasma metabolites, oxidative stress and energy reserves, was used to assess starvation effects on the fish Hoplosternum littorale. Adult specimens were maintained at four experimental groups: control (fed ad libitum), and starved (not fed) fish for 7 and 28 days. Significant changes were observed not only after 28 days, but also after 7 days of starvation. In the shorter period, the hepatosomatic index as well as plasma triglycerides and glucose were significantly lower in starved fish than in the control ones. These results were accompanied by reduced lipid, glycogen and protein reserves in liver and diminished glycogen content in muscle, suggesting the need of these macromolecules as fuel sources. In addition, increased antioxidant enzyme activities were observed in gills, without evidence of oxidative stress in any of the evaluated tissues. Most significant differences were found in 28-days starved fish: total body weight together with the hepatosomatic index was lower when compared to control fish. The plasmatic metabolites tested (glucose, triglyceride, cholesterol and protein), all energy reserves in liver and glycogen content in muscle decreased in 28-days starved fish. Lipid oxidative damage was reported in liver, kidney and brain, and antioxidant enzymes (GST, GR, GPx and CAT) were activated in gills. According to the multivariate analysis, oxidative stress markers and metabolic parameters were key biomarkers that contributed in separating starved from fed fish. Our study allowed an integrated assessment of the fish response to this particular condition.     

High molecular weight water-soluble chitosan protects against apoptosis induced by serum starvation in human astrocytes

The effect of high molecular weight water-soluble chitosan (WSC) on serum starvation-induced apoptosis in human astrocytes (CCF-STTG1 Cells) was investigated. WSC, having an average molecular weight of 300 kDa and a degree of deacetylation over 90%, can be produced using a simple multi-step membrane separation process. Serum starvation led to growth arrest, rounding up of cells and appearance of p53 bands. Prolonged (48 h) incubation in serum starved medium led to cell detachment and death. WSC significantly protected the serum starvation-induced cellular rounding up and protected the serum starvation-induced cell death as tested by flow cytometry. WSC also protected serum starvation-induced p53 activation as determined by Western blot. These results suggest that WSC may prevent serum starvation-induced apoptosis of CCF-STTG1 cells via p53 inactivation.     

Body composition, weight status, body image and weight control practices among female adolescents from eastern Austria

The prevalence rates of obesity, but also of altered eating behaviour up to clinically manifested eating disorders have increased dramatically during the last years. In the present study the weight status, body composition and eating behaviour as well as weight controlling strategies of 1752 female adolescents ageing between 12 and 18 years (x=14.6) from Eastern Austria were documented. Furthermore, data regarding socioeconomic status and educational level of the probands were collected. It could be shown, that a higher educational level or a higher socioeconomic status was associated with a significantly lower fat percentage and a significantly lower prevalence of overweight and obesity. Underweight and severe underweight was predominantly found among girls ageing between 15 and 18 years of higher educational level. Weight controlling behaviour such as stepping on scale and altered or restricted eating behaviour was widespread among the probands, independent of weight status and socioeconomic parameters. Body weight and shape concerns were also found very frequently independent of educational level. The results of the present study corroborate the findings of former investigations, that disturbed eating behaviour and concerns regarding body weight and shape are found among all socioeconomic groups.     

Exogenous strigolactones impact metabolic profiles and phosphate starvation signalling in roots

Strigolactones (SLs) are important ex-planta signalling molecules in the rhizosphere, promoting the association with beneficial microorganisms, but also affecting plant interactions with harmful organisms. They are also plant hormones in-planta, acting as modulators of plant responses under nutrient-deficient conditions, mainly phosphate (Pi) starvation. In the present work, we investigate the potential role of SLs as regulators of early Pi starvation signalling in plants. A short-term pulse of the synthetic SL analogue 2′-epi-GR24 promoted SL accumulation and the expression of Pi starvation markers in tomato and wheat under Pi deprivation. 2′-epi-GR24 application also increased SL production and the expression of Pi starvation markers under normal Pi conditions, being its effect dependent on the endogenous SL levels. Remarkably, 2′-epi-GR24 also impacted the root metabolic profile under these conditions, promoting the levels of metabolites associated to plant responses to Pi limitation, thus partially mimicking the pattern observed under Pi deprivation. The results suggest an endogenous role for SLs as Pi starvation signals. In agreement with this idea, SL-deficient plants were less sensitive to this stress. Based on the results, we propose that SLs may act as early modulators of plant responses to P starvation.     

Body weight,energy metabolism,and time in the life of birds

The breeding of birds, both large and small, is affected by two specific factors: (1) hypometry of egg weight relative to female body weight and (2) seasonality of breeding, with the favorable period being limited and almost equal for birds of different body sizes. Dozens of published allometric formulas describing the dependence of energy parameters of eggs and nestlings at different growth stages and the energy cost of parental care on the body weight of parents, eggs, and nestlings, respectively, are reviewed. It is shown that birds, especially species with a large body weight, repeatedly change their metabolic parameters during ontogeny in order to shorten the period of breeding and growth. In most species, the energy costs of breeding in both sexes are approximately equal. Bringing food in the bill allows birds to supply nestlings with the amount of energy that is dozens of times greater than that expended for obtaining the food. In placental mammals, only females are involved in offspring development. Therefore, the growth rate of embryos and energy expenditures for milk feeding are limited by the metabolic potential of the mother. As a consequence, mammalian offspring grow ten times slower than bird nestlings, the body weights of females being equal.