Evidence of prokaryote like protein associated with nickel resistance in higher plants: horizontal transfer of TonB-dependent receptor/protein in Betula genus or de novo mechanisms?

Mechanisms of metal resistance have been reported in many plants but knowledge in woody species is scarce. The TonB-dependent receptors family (TBDTs) is a large group of proteins that facilitate the transport of molecules across the membrane of Gram-negative bacteria. Some evidence exists that TBDTs are involved in metal stress. The existence of a TonB-like mechanism in non-prokaryotes has not been established. The recent development of the Betula papyrifera (white birch) transcriptome has allowed the discovery of genes involved in plant adaptation to stress. The main objective of the present study was to identify novel genes associated with nickel resistance in B. papyrifera. Our results from next generation sequencing and RT-qPCR analyses show that genes involved in transport activities are upregulated in nickel-resistant genotypes compared with susceptible forms. Detailed analysis of gene expression and genome analysis shows for the first time the existence of a TonB-dependent receptor and TonB-like family protein in non-prokaryotes. In addition, we have found that these proteins are associated with nickel resistance in B. papyrifera. Our experiments suggest that the TonB-dependent receptor may be exclusive to the Betula genus, suggesting that Betula species may have acquired the gene via horizontal gene transfer from prokaryotes or fungi.

Impact of supervisor support on work ability in an IT company.

BACKGROUND: Work ability is the ability of a worker to perform his job. The authors hypothesized that supervisor support influences the work ability of workers working in an information technology company located in Tokyo. AIMS: To assess whether or not support from supervisors influences work ability. METHODS: Two surveys using the Brief Job Scale Questionnaire and the Work Ability Index (WAI) were conducted, one in October 2007 and the other in October 2008 on the same cohort. Two cross-sectional analyses and a 1-year longitudinal analysis were conducted using multiple regression analysis. In addition, the relationships between supervisor support and each dimension of WAI were analysed separately. RESULTS: The number of participants was 1157 males. Significant relationships were observed between supervisor support and WAI scores in both survey periods after adjusting for age, job demand, job control, work group size, job rank and job type. The 2007 Supervisor support was a significant predictor of 2008 WAI that raised the possibility that supervisor support does influence WAI scores. From the analysis of each dimension of WAI, a strong relationship between supervisor support and WAI was observed for the sections of the WAI that assessed work capacity but not for the sections that assessed the personal health status of respondents. CONCLUSIONS: Supervisor support is an important predictor of work ability. Supervisor support is associated with the questions of the WAI that assess not only work demands but also person's resources of the work ability model.

Occupational rhinitis in workers investigated for occupational asthma.

BACKGROUND: The links between asthma and rhinitis are now referred to as united airways disease (UAD). Current evidence shows that the UAD model seems to be applicable to occupational rhinitis (OR) and occupational asthma (OA). A study was undertaken to objectively assess, in the context of specific inhalation challenge (SIC) testing, the concomitance of bronchial and nasal reaction in the investigation of OR and OA. METHODS: 43 subjects with a history of work-related asthma symptoms underwent SIC for confirmation of OA and investigation of OR. Changes in bronchial calibre were measured by spirometry and nasal patency and airway inflammation were assessed by acoustic rhinometry and nasal lavage. RESULTS: A positive nasal challenge was observed in 25 SIC tests and a positive bronchial challenge was observed in 17 SIC tests. A concomitant positive nasal and bronchial challenge was observed in 13 instances. This association was significant (risk ratio = 1.7; 95% CI 1.0 to 2.4; p = 0.04) and more frequent in subjects challenged with high molecular weight agents (n = 11/22) than with low molecular weight agents (n = 2/21). In subjects with a positive nasal challenge, nasal lavage showed a significant increase in eosinophils 30 min after exposure which correlated with changes in nasal patency. CONCLUSION: The results of this study provide objective evidence to support the concept of UAD using OR and OA as a model to demonstrate a significant concomitant physiological reaction of the nose and lungs after challenge. This study shows that OR can be assessed by objective means; it often coexists with OA but can be present without OA.

Nitrogen fertilizer impact on the Wilmot watershed aquifer in Prince Edward Island, Canada.

The objective of this study is to estimate the soil N flux from the vadose zone to the aquifer of the Wilmot watershed (Prince Edward Island, Canada) for a typical three-year cropping rotation (barley-red clover-potato). A conceptual model estimates that 199-221 tons of N were yearly available for leaching at the watershed scale. A significant portion of this N amount was available for leaching at the end of the crop season representing 80-90% of the annual N balance. Drainage water nitrate concentrations were significantly higher after the potato-rotation year than during the crop season. Low nitrate concentrations were measured at spring thaw indicating that most of the nitrate available from the preceding potato crop season was likely leached at the end of fall or during winter. Early spring ionic exchange membrane sampling show a large availability of nitrate in soil possibly throughout winter as well, resulting from soil N mineralization and nitrification over the winter period. These findings are corroborated by the isotope natural abundance analysis of nitrate in groundwater implying that nitrifiers are significantly active during winter, as well as during the crop season, and that leaching of soil nitrates with seasonal signals takes place whenever recharge is occurring.

Indicator of risk of water contamination by phosphorus from Canadian agricultural land.

The indicator of risk of water contamination by phosphorus (IROWC_P) is designed to estimate where the risk of water P contamination by agriculture is high, and how this risk is changing over time based on the five-year period of data Census frequency. Firstly developed for the province of Quebec (2000), this paper presents an improved version of IROWC_P (intended to be released in 2008), which will be extended to all watersheds and Soil Landscape of Canada (SLC) polygons (scale 1:1, 000, 000) with more than 5% of agriculture. There are three objectives: (i) create a soil phosphorus saturation database for dominant and subdominant soil series of SLC polygons--the soil P saturation values are estimated by the ratio of soil test P to soil P sorption capacity; (ii) calculate an annual P balance considering crop residue P, manure P, and inorganic fertilizer P--agricultural and manure management practices will also be considered; and (iii) develop a transport-hydrology component including P transport estimation by runoff mechanisms (water balance factor, topographic index) and soil erosion, and the area connectivity to water (artificial drainage, soil macropores, and surface water bodies).

Role of deep abdominal fat in the association between regional adipose tissue distribution and glucose tolerance in obese women.

Computed tomography (CT) was used to study the association between adipose tissue localization and glucose tolerance in a sample of 52 premenopausal obese women aged 35.7 +/- 5.5 yr (mean +/- SD) and with a body fat of 45.9 +/- 5.5%. Body-fat mass and the body mass index (BMI) were significantly correlated with plasma glucose, insulin, and connecting peptide (C-peptide) areas after glucose (75 g) ingestion (.40 less than or equal to r less than or equal to .51, P less than .01). Trunk-fat accumulation and the size of fat cells in the abdomen displayed highly significant correlations with postglucose insulin levels. The C-peptide area was also positively correlated with abdominal fat cell size (r = .76, P less than .01) and was more closely associated with the sum of trunk skin folds (r = .59, P less than .001) than with the extremity skin folds (r = .29, P less than .05). Subcutaneous and deep-abdominal-fat areas measured by CT displayed comparable associations with the plasma insulin area (r = .44 and .49, respectively; P less than .001) but marked differences in the associations with glucose tolerance. Indeed, subcutaneous abdominal fat was not significantly correlated with the glucose area, whereas deep abdominal fat showed a significant correlation (r = .57, P less than .001) with the glucose area. Midthigh fat deposition measured by CT was not, however, correlated with plasma glucose, insulin, or C-peptide areas.(ABSTRACT TRUNCATED AT 250 WORDS)

Thyroid hormones and thyrotropin variations during long term overfeeding in identical twins.

The aim of this study was to evaluate variations in plasma thyroid hormones and TSH during a standardized long term overfeeding protocol (4.2 megajoules/day [corrected] during a 100-day period) in 24 lean adults (12 pairs of monozygotic twins) and to assess their relationships with body composition and resting metabolic rate (RMR) changes. Compared to preoverfeeding values, basal plasma T3 concentrations were increased on day 25, but not later; basal plasma T4 and free T4 (FT4) concentrations were unchanged; basal plasma rT3 concentrations were persistently decreased throughout the entire protocol; and the TSH response to TRH stimulation was persistently enhanced. The TSH response to TRH before overfeeding was positively correlated with the changes in RMR with overfeeding (r = -0.53; P < 0.01). No association was found between changes in basal plasma T3 concentrations and changes in RMR. However, changes in basal T3 were positively related to changes in body weight (r = 0.46; P < 0.05). A significant within-pair similarity was found for changes in T4 and FT4 with overfeeding (P < 0.05). We conclude that 1) during overfeeding, the early increase in T3 concentrations is a transitory phenomenon, whereas the decrease in rT3 concentrations and the increased TSH response to TRH are more sustained; 2) the TSH responsiveness to TRH stimulation could be a predictor of the changes in RMR during times of increased energy intake; 3) there is no evidence for a direct role of T3 in the adaptation of resting energy expenditure during a long term overfeeding protocol; and 4) the genotype could be involved in the changes in T4 and FT4 during a prolonged positive energy balance period.

Abdominal fat cell lipolysis, body fat distribution, and metabolic variables in premenopausal women.

It is well established that abdominal obesity is related to numerous metabolic abnormalities and that this correlation represents a significant risk factor for coronary heart disease and related mortality. In the present study the relationships among the regional distribution of body fat, selected metabolic variables, and abdominal adipose cell lipolysis were investigated in 30 premenopausal women, 34 +/- 8 yr (mean +/- SD) of age, with body mass indices ranging from 17-45 kg/m2. Basal as well as epinephrine- and isoproterenol-stimulated lipolyses were positively correlated with fasting plasma insulin and triglyceride levels (0.48 less than r less than 0.64; 0.05 greater than P less than 0.0005 and 0.46 less than r less than 0.60; 0.05 greater than P less than 0.005, respectively) and with the insulin area measured during an oral glucose tolerance test (0.49 less than r less than 0.67; 0.005 greater than P less than 0.0005). With the exception of epinephrine-stimulated lipolysis, these correlations remained significant when lipolysis was corrected for cell surface area. Basal and maximal epinephrine- and isoproterenol-induced lipolyses were also negatively related to plasma high density lipoprotein cholesterol (-0.52 less than r less than -0.36; 0.05 greater than P less than 0.005). However, these relationships were no longer significant after control for fat cell surface. The associations between abdominal lipolysis and fat distribution did not remain significant when data were adjusted for total adiposity. Taken together, these results support the notion that variations in abdominal adipocyte lipolysis 1) depend more on total body fatness than on fat distribution, and 2) may be involved in the metabolic complications associated with abdominal obesity, particularly those pertaining to plasma insulin and triglyceride metabolism.

Cloning of Pseudomonas plasmid pMG7 and its restriction-modification system in Escherichia coli.

Plasmid pMG7 of Pseudomonas aeruginosa codes for a type II DNA restriction-modification (r-m) system, PaeR7. This plasmid has not been observed to transfer to Escherichia coli either by conjugation or by transformation. We have cloned BglII linears (42 kb) and the BamHI large fragment (37 kb) of pMG7 into cosmid pHC79 (6.4 kb) and introduced the recombinant molecules into E. coli by in vitro packaging. Several clones were obtained which demonstrated in vivo restriction of phage phi 80. One of these clones, GT138, was further tested and showed in vivo modification of phi 80. Extracts from two clones, GT138 and GT125, yielded a restriction endonuclease activity which produced fragments of phi 80 DNA identical to those produced by PaeR7. Cosmid cloning should be useful for obtaining substantial yields of large fragments of plasmids that are difficult to purify in their native strains.

Overfeeding and energy expenditure in humans.

The effect of overfeeding on energy expenditure was investigated in 23 young men subjected to a 353-MJ energy intake surplus over 100 d. The major part of this excess (222 MJ) was stored as body energy. The increase in energy cost of weight maintenance amounted to 52 MJ and was proportional to body weight gain. When it was added to the obligatory cost of fat and fat-free mass gains, the overall increase in energy expenditure amounted to a mean of 100 MJ. Four months after overfeeding, subjects had lost 82%, 74%, and 100% of the overfeeding gain in body weight, fat mass, and fat-free mass, respectively. We conclude that 1) in response to overfeeding, two-thirds of the excess energy intake is stored as body energy; 2) overfeeding induces an increase in energy cost of weight maintenance proportional to body weight gain, and 3) preoverfeeding energy balance tends to be restored when nonobese individuals return to their normal daily-life habits.

Human resting energy expenditure in relation to dietary potassium.

This study investigates the putative effect of potassium on energy expenditure. Eight young adult men were submitted to two different normocaloric mixed diets in a randomized order, containing either 163 +/- 9 or 69 +/- 2 mmol potassium/d. On the fifth day of each diet, after an overnight fast, resting metabolic rate (RMR) was measured over a 1-h period. After these measurements, either a potassium load (50 mmol) or a placebo were given to subjects submitted to the low- or the high-potassium diet, respectively. RMR was then measured again for 3 h and the last hour was kept for further analysis. Results showed that acute and chronic variations in potassium intake do not induce significant changes in RMR, and chronic but not acute changes in serum potassium concentration were significantly correlated with changes in energy expenditure (r = 0.74, P less than 0.05) by mechanisms that remain to be elucidated.

Genotype-controlled changes in body composition and fat morphology following overfeeding in twins.

This study investigated the effects of overfeeding on the body composition and fat morphology characteristics of 6 pairs of male monozygotic twins. Each participant was submitted to a 22-day overfeeding period, supplemented by an additional 1000 kcal/day. Significant changes were observed in body composition and fat morphology as shown by increases in body weight, fat mass, sum of 9 skinfolds, and fat cell diameter. Significant within-pair resemblance for absolute changes was observed for body weight, percent body fat, fat mass, sum of skinfolds, trunk skinfolds, and extremity skinfolds, suggesting a role for the genotype in determining the sensitivity of the response to an energy surplus. Significant within-pair resemblance was noted for the biceps, triceps, and thigh with less resemblance noted in the subscapular, abdomen, suprailiac, calf, axillary, and chest sites, suggesting a variation in genotype dependency for subcutaneous fat. The results suggest that changes in body fat following short-term overfeeding appear to have a genetic basis.

A method to assess energy expenditure in children and adults.

A variety of studies has a need to estimate the amount and pattern of daily energy expenditure. To this end, a 3-day activity record was developed and is described. Every 15-min period over 3 days, including a weekend day, was qualified in terms of energy cost on a 1 to 9 scale corresponding to a range of 1.0 MET to 7.8 METs and higher. A reliability study of 61 subjects indicated a highly reproducible procedure as shown by an intraclass correlation of 0.96 for mean kcal of energy expenditure over 3 days. Repeatability was unchanged whether or not the hours of sleep were included in the record. Samples of 150 children and 150 adults were also drawn to investigate the relationship between energy expenditure, physical working capacity, and body fatness. Results support the hypothesis that mean energy expenditure per kg of body weight is significantly correlated with physical working capacity expressed per kg of body weight (r = 0.31; p less than 0.01). Mean energy expenditure per kg of body weight is negatively related to body fat (-0.08 less than or equal to r less than or equal to -0.13). It is concluded that the 3-day activity record is a procedure suitable to estimate energy expenditure in population studies.

Linkage of the Na,K-ATPase alpha 2 and beta 1 genes with resting and exercise heart rate and blood pressure: cross-sectional and longitudinal observations from the Quebec Family Study.

OBJECTIVE: To investigate whether genetic variations in the genes encoding the alpha and beta subunits of the Na,K-ATPase are linked with hemodynamic phenotypes. DESIGN AND PARTICIPANTS: Cross-sectional data based on 533 subjects (no antihypertensive medication) were obtained from 150 families of phase 2 of the Quebec Family Study, together with longitudinal data from 338 subjects (105 families) who had been measured 12 years earlier in phase 1 of the Quebec Family Study. MAIN OUTCOME MEASURES: Restriction fragment length polymorphisms were examined at the alpha 2 (exon 1 and exon 21-22 with BglII) and beta 1 (Msp I and Pvu II) loci of Na,K-ATPase. Hemodynamic phenotypes measured included systolic and diastolic blood pressure, heart rate and rate-pressure product at rest and during low-intensity exercise. RESULTS: Sib-pair analysis revealed relatively strong linkages (P = 0.0003-0.002) between the resting heart rate and rate-pressure product and the alpha 2 exon 21-22 marker and alpha 2 haplotype. Moreover, the alpha 2 exon 21-22 marker showed suggestive linkages (P = 0.01 to 0.043) with resting systolic blood pressure and exercise diastolic blood pressure, heart rate and rate-pressure product, and the alpha 2 haplotype with exercise diastolic blood pressure and rate-pressure product and the 12-year change in resting systolic blood pressure (P = 0.03 to 0.05). Both the beta 1 Msp I marker and the beta 1 haplotype were linked with the resting rate-pressure product (P = 0.007 and 0.003, respectively), and all beta 1 markers showed linkage with the change in resting systolic blood pressure (P = 0.00005 to 0.024). In men, there was a significant (P = 0.01) interaction between the alpha 2 exon 21-22 genotype and the postglucose plasma insulin level with regard to resting systolic blood pressure. CONCLUSIONS: These data suggest that the alpha 2 and beta 1 genes of Na,K-ATPase contribute to the regulation of hemodynamic phenotypes in healthy subjects.

A retrospective mortality study among Canadian petroleum marketing and distribution workers.

We conducted a retrospective mortality study among 6672 petroleum marketing and distribution workers from 226 locations throughout Canada. These employees worked for at least 1 year in the marketing distribution segment from 1964 through 1983 or were annuitants as of 1964. Industrial hygienists assigned hydrocarbon (HC) exposure frequency scores for several jobs, departments, and job functions. We computed standardized mortality ratios for the total cohort, HC exposure frequency groups, and tank truck drivers, and we also used Poisson regression techniques to model mortality for selected causes of death according to HC exposure frequency. Results indicate overall mortality below that of the general Canadian population for all marketing distribution workers [Standardized mortality ratio (SMR) = 0.88]. Mortality from aortic aneurysms was significantly elevated in all marketing/distribution workers (SMR = 1.79) but was due to raised mortality in nonexposed workers (SMR = 2.80). Tank truck drivers showed significantly elevated mortality due to leukemia (SMR = 3.35) based on five deaths. The leukemia findings were not evident in the larger group of marketing distribution workers classified as exposed to hydrocarbons (SMR = 1.01). No other cause of death was elevated in truck drivers. The leukemia findings are suggestive of a possible influence due to exposure to HCs in tank truck drivers, although other explanations cannot be ruled out. Other findings of elevated mortality in the marketing distribution group are generally not statistically significant. These included moderately increased mortality due to multiple myeloma, malignant melanoma, and kidney cancer. Small numbers of observed and expected deaths limit concise interpretations for these diseases.

Relationships between body fatness, adipose tissue distribution and blood pressure in men and women.

The relationships between body fatness, fat distribution and blood pressure (BP) were studied in 234 women and 238 men, aged 18-50 years. In both sexes, subcutaneous (s.c.) fat (assessed by the measurement of s.c. skinfolds) and percent body fat (measured by underwater weighing) were correlated significantly with diastolic (0.27 less than or equal to r less than or equal to 0.37, p less than 0.0005) and systolic (0.17 less than or equal to r less than or equal to 0.29, p less than 0.01) BP. In either sex, the proportion of s.c. trunk fat as reflected by the ratio of trunk/extremity skinfolds showed significant associations with diastolic (men: r = 0.35, women: r = 0.20, p less than 0.01) and systolic BP (men: r = 0.15, women: r = 0.17, p less than 0.05). Control for the effects of covariables potentially affecting BP (energy intake, energy expenditure, maximal oxygen consumption, cigarette smoking, alcohol intake and age) revealed significant effects of age and alcohol intake on BP in men. In women, only age appeared to be associated with BP variation. Partial correlations after control for age and alcohol intake indicated a significant association between the trunk/extremity skinfolds ratio and diastolic BP in men. Such a correlation was not found in women after control for the effect of age. Analysis of variance (2 x 2 factorial with fixed effects) confirmed that, in men, the distribution of s.c. body fat was, per se, associated with diastolic BP (F = 8.43, p less than 0.01), whereas the proportional of s.c. trunk fat was not related to systolic BP in both sexes.(ABSTRACT TRUNCATED AT 250 WORDS)

Mortality in a historical cohort of bus drivers.

In an attempt to address previously reported excesses of ischaemic heart disease (IHD), lung cancer and bladder cancer among professional drivers, the mortality (SMR) of 2134 Montreal city bus drivers employed for at least five years as of January 1962 and followed until 31 December 1985 was compared with that of the male population of greater Montreal. The vital status of 94% of the cohort was ascertained. The number of deaths observed was 804. The overall mortality was somewhat lower than expected (SMR = 97). A small, non-significant excess mortality was found for ischaemic heart disease (IHD) (O/E = 313/295, SMR = 106, 95% CI: 95-118) and circulatory system diseases (O/E = 441/405, SMR = 109, 95% CI: 99-119). However, no excesses were observed for lung cancer (O/E = 78/84.4, SMR = 92, 95% CI: 73-114) or bladder cancer (O/E = 4/7.4, SMR = 54, 95% CI: 15-138). These results are compatible with other studies which have found a small risk of IHD for bus drivers.

Plasma glucose, insulin, and glucagon before and after long-term overfeeding in identical twins.

Plasma glucose, insulin, and glucagon levels were measured before and after long-term overfeeding (4.2 MJ/d during a 100-day period) in 24 lean adults (12 pairs of monozygotic twins). Fasting plasma glucose, insulin, and glucagon were significantly increased by overfeeding. During a 75-g oral glucose tolerance test (OGTT), no major alteration in glucose tolerance was observed and insulin area under the curve was increased. During a meal test, insulin and glucagon areas under the curve were increased. The pre-overfeeding values for glucose, insulin, and glucagon (fasting and areas) were not correlated with the gains in body weight and in fat mass. However, fasting glucagon before overfeeding was positively correlated with the gains in abdominal visceral fat and in femoral fat. The changes with overfeeding in insulin area during the OGTT were positively correlated with the changes in total subcutaneous fat, even after adjustment for total body fat gain. Significant twin intrapair similarity was observed for fasting plasma glucagon before overfeeding and for the changes in fasting insulin and glucagon with overfeeding. These results indicate that (1) in response to long-term overfeeding, both fasting insulin and glucagon are increased; (2) initial levels of glucose, insulin, and glucagon do not predict the gains in body weight and total body fat during overfeeding, but are related to changes in indicators of fat topography; (3) the changes in total subcutaneous fat represent an important correlate of insulin changes with overfeeding; and (4) the genotype could be an important determinant of insulin and glucagon responses to a prolonged positive-energy-balance period.

Acute effects of endurance exercise on human adipose tissue metabolism.

In order to study the acute effects of exercise on adipose tissue metabolism, 27 sedentary male subjects, 18 to 27 years of age, performed a prolonged aerobic exercise test. Biopsies of adipose tissue were obtained from the suprailiac fat depot before and immediately after a 90-minute period of exercise on ergocycle at an average intensity of 88% of maximal heart rate. Fat cells, isolated by collagenase digestion, were measured for their glucose conversion into triglycerides and for lipolytic activity. Adipose tissue lipoprotein lipase activity released by heparin was also determined. Mean basal and insulin-stimulated glucose conversion into triglycerides decreased significantly with exercise (P less than .05) while adipose tissue lipoprotein lipase activity increased (P less than .01). Fat cell lipolysis increased during exercise only for its epinephrine-stimulated values (P less than .05). The total amount of work performed during the test was correlated only with changes in lipoprotein lipase activity (r = .42, P less than .05). Finally, the changes induced by exercise in lipoprotein lipase activity (r = .37, P less than .05) and insulin-stimulated glucose conversion into triglycerides (r = .61, P less than .01) were positively correlated with fat cell weight. These results indicate that adipose tissue metabolic activities are selectively influenced by endurance exercise. They also suggest that these metabolic changes are not closely coupled with the amount of work performed in a prolonged exercise bout.

Endurance training with constant energy intake in identical twins: changes over time in energy expenditure and related hormones.

The effects of exercise training and of its interaction with the genotype on components of energy expenditure and related hormones were examined in young male monozygotic twins. Energy intake was maintained at the pretraining level for a 93-day training period. The estimated net energy deficit induced by training was 244 MJ and was associated with a 5-kg body weight loss that was almost entirely explained by body fat loss. Resting metabolic rate (RMR) was significantly decreased by 8% after training despite the preservation of fat-free mass (FFM). Accordingly, plasma norepinephrine (NE) concentrations, NE appearance rate, and plasma levels of triiodothyronine (T3), free T3, and total thyroxine (T4) were lower after training. The energy cost of standardized exercise was also reduced after the training program. A modest to significant within-twin-pair resemblance was observed for absolute changes in the RMR, thermic effect of food, energy cost of exercise, NE clearance, and plasma concentrations of thyroid hormones. These results suggest that when exercise training is associated with a substantial negative energy balance, energy expenditure and levels of related hormones are decreased, and this effect is partly accounted for by heredity.