Seasonal energy investment and metabolic patterns in a farmed fish.

The present research focuses on the seasonal changes in the energy content and metabolic patterns of red porgy (Pagrus pagrus) sampled in a fish farm in North Evoikos Gulf (Greece). The study was designed in an effort to evaluate the influence of seasonality in several physiological feauteres of high commercial importance that may affect feed intake and growth. We determined glycogen, lipids and proteins levels, and cellular energy allocation (CEA) as a valuable marker of exposure to stress, which integrates available energy (Ea) and energy consumption (Ec). Metabolic patterns and aerobic oxidation potential were based on the determination of glucose transporter (GLU), carnitine transporter (CTP), L-lactate dehydrogenase (L-LDH), citrate synthase (CS), cytochrome C oxidase subunit IV isoform 1 (COX1) and 3-hydroxyacyl CoA dehydrogenase (HOAD) relative gene expression. To integrate metabolic patterns and gene expression, L-LDH, CS, COX and HOAD activities were also determined. For further estimation of biological stores oxidized during seasonal acclimatization, we determined the blood levels of glucose, lipids and lactate. The results indicated seasonal changes in energy content, different patterns in gene expression and reorganization of metabolic patterns during cool acclimatization with increased lipid oxidation. During warm acclimatization, however, energy consumption was mostly based on carbohydrates oxidation. The decrease of Ec and COX1 activity in the warm exposed heart seem to be consistent with the OCLTT hypothesis, suggesting that the heart may be one of the first organs to be limited during seasonal warming. Overall, this study has profiled changes in energetics and metabolic patterns occurring at annual temperatures at which P. pagrus is currently farmed, suggesting that this species is living at the upper edge of their thermal window, at least during summer.

Cancer metabolism and carcinogenesis.

Metabolic reprogramming is an emerging hallmark of cancer cells, enabling them to meet increased nutrient and energy demands while withstanding the challenging microenvironment. Cancer cells can switch their metabolic pathways, allowing them to adapt to different microenvironments and therapeutic interventions. This refers to metabolic heterogeneity, in which different cell populations use different metabolic pathways to sustain their survival and proliferation and impact their response to conventional cancer therapies. Thus, targeting cancer metabolic heterogeneity represents an innovative therapeutic avenue with the potential to overcome treatment resistance and improve therapeutic outcomes. This review discusses the metabolic patterns of different cancer cell populations and developmental stages, summarizes the molecular mechanisms involved in the intricate interactions within cancer metabolism, and highlights the clinical potential of targeting metabolic vulnerabilities as a promising therapeutic regimen. We aim to unravel the complex of metabolic characteristics and develop personalized treatment approaches to address distinct metabolic traits, ultimately enhancing patient outcomes.

Anti-Diabetic Drugs Inhibit Bulimia Induced Obesity.

BACKGROUND: Obesity is primarily a consequence of food addiction. Drugs have been confirmed effective for weight loss more or less related to the functional connectivity in neural networks and metabolic patterns. Recent studies have shown that some anti-diabetic drugs, such as Metformin and Dapagliflozin have similar weight loss effects, however, their mechanisms are unclear. We hypothesized that the functional connectivity and energy metabolism might be associated with the mechanisms. METHODS: Male ob/ob mice were fed with high-fructose-fat-diet (HFFD) for 4 weeks to esteblish obesity model. Then mice were divided into normal saline (NS, as control), Metformin (Metformin, 50 mg/kg/day by gavage), and Dapagliflozin (Dapagliflozin, 10 mg/kg/day by gavage) groups. Functional connectivity amplitude of low-frequency signal fluctuations and regional cerebral blood volume (rCBV) quantification were statistically analyzed in the linear mixed model, meanwhile, metabolic pattern of intestinal cells (IECs) were also tested. RESULTS: Our results showed that Blood Oxygen on Level Depending (Bold) signaling responses, functional connectivity, and rCBV quantification tended to be attenuated in the Metformin group compared to the control and Dapagliflozin groups. While only Dapagliflozin prevented HFFD induced hyper survival of intestinal cells and hypertrophy of intestinal villus by reducing glycolysis levels. Both Metformin and Dapagliflozin are effective for weight loss. CONCLUSIONS: Our findings showed that Dapagliflozin and Metformin may inhibit bulimia induced obesity with different mechanisms. We speculate that Metformin may affect appetite regulation, while Dapagliflozin can affect the survival and metabolic patterns of intestinal cells, thus significantly affecting the absorption of nutrients. So, combining Metformin and Dapgliflozin may be more beneficial for clinical improvement in bulimia induced obesity.

Pre-clinical Investigations of Therapeutic Markers Associated with Acute and Chronic Restraint Stress: A Nuclear Magnetic Resonance Based Contrast Metabolic Approach.

Stress can be defined by two parameters, first the psychological sensing of pressure and second is the body's response. However, the exposure time to stress depicts the biological response produced against it. The effect of acute and chronic restraint stress on anxiety and the production of systemic metabolites were investigated in male Sprague-Dawley (SD) rats. Behavioural test was performed on elevated plus maze (EPM) in conjunction with the statistical analysis that exhibited the habituation during long term exposure to stress when compared with the short-term stress. These behaviour-based changes resulted in interpolated concentration of some serum metabolites like carbohydrates, amino acids and lipids as analysed by NMR. Metabolic analysis along with the multivariate analysis demonstrated that the expression of concentration of metabolites including glutamate, proline, succinate, citrate, and tyrosine is higher in the acute stress than the chronic stress, while glucose and lipids i.e., LDL and VLDL changed in the opposite trends. Thus, the aforesaid study provides an analytical strategy for the characterization of perturbed metabolites induced due to the behavioural modifications in an organism. It may further aid in developing potential therapeutic markers at the metabolic levels which may broaden the treatment options for stress and anxiety related disorders.

Metabolic remodeling caused by heat hardening in the Mediterranean mussel Mytilus galloprovincialis.

Organisms can modify and increase their thermal tolerance faster and more efficiently after a brief exposure to sublethal thermal stress. This response is called 'heat hardening' as it leads to the generation of phenotypes with increased heat tolerance. The aim of this study was to investigate the impact of heat hardening on the metabolomic profile of Mytilus galloprovincialis in order to identify the associated adjustments of biochemical pathways that might benefit the mussels' thermal tolerance. Thus, mussels were exposed sequentially to two different phases (heat hardening and acclimation phases). To gain further insight into the possible mechanisms underlying the metabolic response of the heat-hardened M. galloprovincialis, metabolomics analysis was complemented by the estimation of mRNA expression of phosphoenolpyruvate carboxykinase (PEPCK), pyruvate kinase (PK) and alternative oxidase (AOX) implicated in the metabolic pathways of gluconeogenesis, glycolysis and redox homeostasis, respectively. Heat-hardened mussels showed evidence of higher activity of the tricarboxylic acid (TCA) cycle and diversification of upregulated metabolic pathways, possibly as a mechanism to increase ATP production and extend survival under heat stress. Moreover, formate and taurine accumulation provide an antioxidant and cytoprotective role in mussels during hypoxia and thermal stress. Overall, the metabolic responses in non-heat-hardened and heat-hardened mussels underline the upper thermal limits of M. galloprovincialis, set at 26°C, and are in accordance with the OCLTT concept. The ability of heat-hardened mussels to undergo a rapid gain and slow loss of heat tolerance may be an advantageous strategy for coping with intermittent and often extreme temperatures.

Characteristics and metabolic patterns of soil methanogenic archaea communities in the high-latitude natural forested wetlands of China.

Soil methanogenic microorganisms are one of the primary methane-producing microbes in wetlands. However, we still poorly understand the community characteristic and metabolic patterns of these microorganisms according to vegetation type and seasonal changes. Therefore, to better elucidate the effects of the vegetation type and seasonal factors on the methanogenic community structure and metabolic patterns, we detected the characteristics of the soil methanogenic mcrA gene from three types of natural wetlands in different seasons in the Xiaoxing'an Mountain region, China. The results indicated that the distribution of Methanobacteriaceae (hydrogenotrophic methanogens) was higher in winter, while Methanosarcinaceae and Methanosaetaceae accounted for a higher proportion in summer. Hydrogenotrophic methanogenesis was the dominant trophic pattern in each wetland. The results of principal coordinate analysis and cluster analysis showed that the vegetation type considerably influenced the methanogenic community composition. The methanogenic community structure in the Betula platyphylla-Larix gmelinii wetland was relatively different from the structure of the other two wetland types. Indicator species analysis further demonstrated that the corresponding species of indicator operational taxonomic units from the Alnus sibirica wetland and the Betula ovalifolia wetland were similar. Network analysis showed that cooperative and competitive relationships exist both within and between the same or different trophic methanogens. The core methanogens with higher abundance in each wetland were conducive to the adaptation to environmental disturbances. This information is crucial for the assessment of metabolic patterns of soil methanogenic archaea and future fluxes in the wetlands of the Xiaoxing'an Mountain region given their vulnerability.

Metabolic patterns reveal enhanced anammox activity at low nitrogen conditions in the integrated I-ABR.

Substrate concentrations greatly influence bacterial growth and metabolism. However, optimal nitrogen concentrations for anammox bacteria in nitrogen-limited environments remain unclear. Here, we observed enhanced nitrogen metabolism and anabolism of anammox bacteria at low nitrogen conditions. Efficient nitrogen removal was achieved at ammonium and nitrite influent concentration of 30 mg/L under HRT of 1 hr, with an average nitrogen removal rate (NRR) of 0.73 kg N/(m3 ·day) in I-ABR composed of four compartments. The highest anammox activity of 6.25 mmol N/ (gVSS·hr) was observed in the fourth compartment (C4) with the lowest substrate levels (ammonium and nitrite of 11.6 mg/L and 7 mg/L). This could be resulted from the highest expression level of genes involved in nitrogen metabolism in C4, which was 1.49-1.67 times higher than that in other compartments. Besides, the second compartment (C2) exhibited the most active anabolism at ammonium and nitrite of 17 mg/L and 13 mg/L, respectively, which contributed to the most active amino acid synthesis and thus the highest EPS (1.35 times higher) in C2. This enhanced amino acid auxotrophy between anammox bacteria with heterotrophs, and consequently, heterotrophs thrived and competed for nitrite. These results hint at the potential application of anammox process in micro-polluted water. PRACTITIONER POINTS: High nitrogen removal and efficient biomass retention at low nitrogen concentrations under short HRT was achieved in I-ABR. Optimal concentrations for anammox nitrogen removal and anabolism were discussed under low nitrogen concentrations. More active anabolism contributed to enhanced amino acid synthesis and thus higher EPS contents. Low substrate levels led to enhanced expression of genes involved in nitrogen metabolism and thus high anammox activity.

Parallel metabolomics and lipidomics enables the comprehensive study of mouse brain regional metabolite and lipid patterns.

Global profiling of the metabolome and lipidome of specific brain regions is essential to understanding the cellular and molecular mechanisms regulating brain activity. Given the limited amount of starting material, conventional mouse studies comparing brain regions have mainly targeted a set of known metabolites in large brain regions (e.g., cerebrum, cortex). In this work, we developed a multimodal analytical pipeline enabling parallel analyses of metabolomic and lipidomic profiles from anatomically distinct mouse brain regions starting with less than 0.2 mg of protein content. This analytical pipeline is composed of (1) sonication-based tissue homogenization, (2) parallel metabolite and lipid extraction, (3) BCA-based sample normalization, (4) ultrahigh performance liquid chromatography-mass spectrometry-based multimodal metabolome and lipidome profiling, (5) streamlined data processing, and (6) chord plot-based data visualization. We applied this pipeline to the study of four brain regions in males including the amygdala, dorsal hippocampus, nucleus accumbens and ventral tegmental area. With this novel approach, we detected over 5000 metabolic and 6000 lipid features, among which 134 metabolites and 479 lipids were directly confirmed via automated MS2 spectral matching. Interestingly, our analysis identified unique metabolic and lipid profiles in each brain regions. Furthermore, we identified functional relationships amongst metabolic and lipid subclasses, potentially underlying cellular and functional differences across all four brain regions. Overall, our novel workflow generates comprehensive region-specific metabolomic and lipidomic profiles using very low amount of brain sub-regional tissue sample, which could be readily integrated with region-specific genomic, transcriptomic, and proteomic data to reveal novel insights into the molecular mechanisms underlying the activity of distinct brain regions.

Are pigs a suitable animal model for in vivo metabolism studies of new psychoactive substances? A comparison study using different in vitro/in vivo tools and U-47700 as model drug.

Being highly potent, New Synthetic Opioids (NSO) have become a public health concern. Little is known though about the metabolism and toxicokinetics (TK) of many of the non fentanyl NSO such as U-47700. Obtaining such data in humans is challenging and so we investigated if pigs were a suitable model species as TK model for U-47700. The metabolic fate of U-47700 was elucidated after intravenous administration to one pig in vivo and results were compared to metabolic patterns formed by different other in vitro systems (human and pig liver microsomes, human liver S9 fraction) and compared to rat and human in vivo data. Furthermore, monooxygenase isozymes responsible for the major metabolic steps were elucidated. In total, 12 phase I and 8 phase II metabolites of U-47700 could be identified. The predominant reactions were N-demethylation, hydroxylation, and combination of them followed by glucuronidation or sulfation. The most predominant monooxygenase catalyzed conversions were N-demethylation, and hydroxylation by CYP3A4 and 2B6, and FMO3 catalyzed N-oxidation. Similar main phase I metabolites were found in vitro as compared to in vivo (pig/human). The metabolic pattern elucidated in the pig was comparable to human in vivo data. Thus, pigs seem to be a suitable animal model for metabolism and further TK of U-47700.

Dietary habits and physical activity in first-episode psychosis patients treated in community services. Effect on early anthropometric and cardio-metabolic alterations.

People with psychosis often develop metabolic and cardiovascular disorders, due to several factors including unhealthy lifestyle and antipsychotic treatment. This study aims to evaluate in a sample of first episode psychosis (FEP) patients lifestyle factors, with a specific emphasis on dietary habits and physical activity, and cardio-metabolic and anthropometric profile at illness onset and at 9 months. Moreover, this study aims to evaluate the impact of lifestyle factors on short term changes in cardio-metabolic and anthropometric profile. A 9-month follow-up study was conducted on a sample of 96 FEP patients recruited within the context of the GET UP program. Standardised assessments of dietary habits (EPIC) and physical activity (IPAQ) were retrospectively performed at 9 months; cardiovascular measures (blood pressure, heart rate), metabolic parameters (glucose, cholesterol, triglycerides), BMI and antipsychotic treatment were assessed at illness onset and at 9 months. We found that most FEP patients (60%) displayed poor dietary habits, as defined in terms of adherence to the Mediterranean diet. A significant increase for both BMI and cholesterol levels was found in the overall sample over 9 months. However, when considering the effect of lifestyle factors, BMI and total cholesterol were specifically raised in patients with low adherence to Mediterranean diet. The association with antipsychotic medication was found for SGA only, with a significant increase in both BMI and total cholesterol overtime. Our findings confirm the need to implement specific and early strategies to promote healthy lifestyle in people with FEP, since metabolic alterations occur within the first months of treatment.

Bacterial IAA-Delivery into Medicago Root Nodules Triggers a Balanced Stimulation of C and N Metabolism Leading to a Biomass Increase.

Indole-3-acetic acid (IAA) is the main auxin acting as a phytohormone in many plant developmental processes. The ability to synthesize IAA is widely associated with plant growth-promoting rhizobacteria (PGPR). Several studies have been published on the potential application of PGPR to improve plant growth through the enhancement of their main metabolic processes. In this study, the IAA-overproducing Ensifer meliloti strain RD64 and its parental strain 1021 were used to inoculate Medicago sativa plants. After verifying that the endogenous biosynthesis of IAA did not lead to genomic changes during the initial phases of the symbiotic process, we analyzed whether the overproduction of bacterial IAA inside root nodules influenced, in a coordinated manner, the activity of the nitrogen-fixing apparatus and the photosynthetic function, which are the two processes playing a key role in legume plant growth and productivity. Higher nitrogen-fixing activity and a greater amount of total nitrogen (N), carbon (C), Rubisco, nitrogen-rich amino acids, soluble sugars, and organic acids were measured for RD64-nodulated plants compared to the plants nodulated by the wild-type strain 1021. Furthermore, the RD64-nodulated plants showed a biomass increase over time, with the highest increment (more than 60%) being reached at six weeks after infection. Our findings show that the RD64-nodulated plants need more substrate derived from photosynthesis to generate the ATP required for their increased nitrogenase activity. This high carbohydrate demand further stimulates the photosynthetic function with the production of molecules that can be used to promote plant growth. We thus speculate that the use of PGPR able to stimulate both C and N metabolism with a balanced C/N ratio represents an efficient strategy to obtain substantial gains in plant productivity.

Seasonal Changes in Metabolism and Cellular Stress Phenomena in the Gilthead Sea Bream (Sparus aurata).

Seasonal temperature changes may take organisms to the upper and lower limit of their thermal range, with respective variations in their biochemical and metabolic profile. To elucidate these traits, we investigated metabolic and antioxidant patterns in tissues of sea bream Sparus aurata during seasonal acclimatization for 1 yr in the field. Metabolic patterns were assessed by determining lactate dehydrogenase, citrate synthase, and ß-hydroxyacyl CoA dehydrogenase activities, their kinetic properties and plasma levels of glucose, lactate, and triglycerides and tissue succinate levels. Oxidative stress was assessed by determining antioxidant enzymes superoxide dismutase, catalase, and glutathione reductase activities and levels of thiobarbituric acid reactive substances. Xanthine oxidase (XO) activity was determined as another source of reactive oxygen species (ROS) production. Furthermore, we studied the antiapoptotic protein indicator Bcl-2 and the apoptotic protein indicators Bax, Bad, ubiquitin, and caspase as well as indexes of autophagy (LC3B II/LC3B I and SQSTM1/p62) in the liver and the heart to identify possible relationships between oxidative stress and cell death. The results indicate clear seasonal metabolic patterns involving oxidative stress during summer as well as winter. During cold acclimatization, lipid oxidation is induced, while during increased temperatures, warm-induced metabolic activation and carbohydrate oxidation are observed. Thus, oxidative stress seems to be more prominent during warming because of the increased aerobic metabolism. The seasonal profile of apoptosis and XO as another source of ROS matches the results obtained in the laboratory and are interpreted within the framework of oxygen- and capacity-limited thermal tolerance.

Metabolic patterns of JWH-210, RCS-4, and THC in pig urine elucidated using LC-HR-MS/MS: Do they reflect patterns in humans?

The knowledge of pharmacokinetic (PK) properties of synthetic cannabinoids (SCs) is important for interpretation of analytical results found for example in intoxicated individuals. In the absence of human data from controlled studies, animal models elucidating SC PK have to be established. Pigs providing large biofluid sample volumes were tested for prediction of human PK data. In this context, the metabolic fate of two model SCs, namely 4-ethylnaphthalen-1-yl-(1-pentylindol-3-yl)methanone (JWH-210) and 2-(4-methoxyphenyl)-1-(1-pentyl-indol-3-yl)methanone (RCS-4), was elucidated in addition to Δ9 -tetrahydrocannabinol (THC). After intravenous administration of the compounds, hourly collected pig urine was analyzed by liquid chromatography-high resolution mass spectrometry. The following pathways were observed: for JWH-210, hydroxylation at the ethyl side chain or pentyl chain and combinations of them followed by glucuronidation; for RCS-4, hydroxylation at the methoxyphenyl moiety or pentyl chain followed by glucuronidation as well as O-demethylation followed by glucuronidation or sulfation; for THC, THC glucuronidation, 11-hydroxylation, followed by carboxylation and glucuronidation. For both SCs, parent compounds could not be detected in urine in contrast to THC. These results were consistent with those obtained from human hepatocyte and/or human case studies. Urinary markers for the consumption of JWH-210 were the glucuronide of the N-hydroxypentyl metabolite (detectable for 3-4 h) and of RCS-4 the glucuronides of the N-hydroxypentyl, hydroxy-methoxyphenyl (detectable for at least 6 h), and the O-demethyl-hydroxy metabolites (detectable for 4 h). Copyright © 2016 John Wiley & Sons, Ltd.

Consistent 1,3-propanediol production from glycerol in mixed culture fermentation over a wide range of pH.

BACKGROUND: Glycerol is currently an over-produced chemical that can be used as substrate for the production of high value products such as 1,3-propanediol (1,3-PDO) in fermentation processes. The aim of this study was to investigate the effect of initial pH on a batch mixed culture fermentation of glycerol, considering both the bacterial community composition and the fermentation patterns. RESULTS: For pH values between 5 and 9, 1,3-PDO production yields ranged from 0.52 ± 0.01 to 0.64 ± 0.00 [Formula: see text], with the highest values obtained at pH 7 and 8. An Enterobacteriaceae member closely related to Citrobacter freundii was strongly enriched at all pH values. Within the less dominant bacterial species, two different microbial community structures were found, one at acid pH values and another at neutral to basic pH values. CONCLUSIONS: 1,3-PDO production was improved at pH values over 7. It was anti-correlated with lactate and ethanol production but positively correlated with acetate production. No direct correlation between 1,3-PDO production and a specific family of bacteria was found, suggesting functional redundancies in the microbial community. However, 1,3-PDO production yield remained high over the range of pH studied and was comparable to the best obtained in the same conditions in the literature.

The pattern of lipids and lipoproteins during the menopausal transition in Chinese women.

Objective To investigate changes in levels of lipids and lipoproteins in Chinese women during perimenopause and postmenopause as primary study endpoints, for the first time including lipoprotein(a). Methods The retrospective study was performed in 1015 women without hormone therapy aged 34-76 years from 20 provinces of China who visited the Beijing Obstetrics & Gynecology hospital. Menopausal status was defined by the criteria of the 2011 Stages of Reproductive Aging Workshop. Results Levels of total cholesterol, triglycerides and low density lipoprotein (LDL) cholesterol increased and that of high density lipoprotein (HDL) cholesterol decreased in the postmenopausal compared to the perimenopausal group. In the women with body mass index (BMI) ≥ 25 kg/m(2), total cholesterol and LDL cholesterol increased, HDL cholesterol decreased and changes in triglyceride levels were not significant. In the women with BMI < 25 kg/m(2), the increase in triglyceride levels during the transition was significant. Changes in lipoprotein(a), apolipoprotein A1 and apolipoprotein B were not significant. Comparing the groups with BMI ≥ 25 kg/m(2) vs. BMI < 25 kg/m(2), only the differences for apolipoprotein A1 and for triglycerides were significant. Triglycerides correlated positively with follicle stimulating hormone and BMI, and total cholesterol correlated positively with follicle stimulating hormone and age (all p < 0.05). Conclusions Some changes in lipids can be related to menopausal status, some to increasing age, some to both; especially triglycerides and apolipoprotein A1 were found also to be related to BMI. Surprisingly lipoprotein(a) did not change either with increasing age or during the transition despite known possible interference with estrogenic status.

Validación de l fórmula de friedewald para la determinación del perfil lipídico en oovinos / Valiation of friiedewald's formula for determining cattle lipid profile

Objetivo: Validar la fórmula de Friedewald para la determinación de los valores de colesterol LDL en bovinos, una especie con patrón metabólico HDL. Materiales y Métodos: Fueron tomadas 100 muestras de sangre de bovinos de diferente edad, raza y sexo. Luego de extraer el suero, fueron determinados los niveles de colesterol LDL mediante el método directo, posteriormente se determinaron los mismos valores utilizando la fórmula de Friedewald. Los resultados fueron analizados estadísticamente mediante ANOVA de una vía. Resultados: El método directo reportó valores (mg/dl) de promedio, mínimo, máximo, y desviación estándar de 40,769; 2,438; 126,751; 29,814, respectivamente, y el método de Friedewald mostró resultados en promedio, mínimo, máximo y desviación estándar de 34,659; 1,349; 145,31; 29,108, correspondientemente. El valor de P en el test F en la comparación del método Directo vs. Friedewald fue mayor o igual a 0,05 (0,154), por lo cual no se evidenció diferencia significativa a un nivel de confianza del 95% entre los valores obtenidos por los dos métodos. Conclusión: Puede ser utilizada la fórmula de Friedewald para la determinación del colesterol LDL en especies con patrón HDL.

Objective: To validate Friedewald's formula for determing LDL cholesterol levels in cattle, species with HDL metabolic pattern. Materials and Methods: One hundred (100) blood samples from different age, race and gender cattle were taken. After removing the serum, the LDL cholesterol levels were determined using the direct method and later the same values were determined using Friedewald's formula. Results were statistically analyzed using one-way ANOVA. Results: The direct method reported values (mg/dl) of average, minimum range, maximum range, and standard deviation of 40.769, 2.438, 126.751, 29.814, respectively, and Friedewald method results showed minimum, maximum and standard deviation averages of 34.659, 1.349, 145.31, 29.108, respectively. The value of P in the F test Direct in the comparison of the direct method and Friedewald's method was greater than or equal to 0.05 (0.154), reason why no significant difference was evident at a level of confidence of 95% between the values obtained through the two methods. Conclusion: Friedewald's formula can be used for determining LDL cholesterol in species with HDL pattern.

Moult and basal metabolic costs in males of two subspecies of stonechats: the European Saxicola torquata rubicula and the East African S. t. axillaris.

The circannual patterns in resting metabolic rate (RMR) of males of two subspecies of stonechats, the European Saxicola torquata rubicula and the East African S. t. axillaris, are compared. As the birds from the two subspecies were raised and kept under comparable laboratory conditions, differences in metabolic rate between the two subspecies had to be genetically determined. RMR peaked during moult in both subspecies. During the rest of the year RMR was fairly constant in both subspecies and assumed to reflect basal metabolic rate (BMR). African stonechats had a 22% lower mass specific BMR than European stonechats, which is thought to reflect a genetical physiological adaptation to the differences in environmental circumstances they experience in the field. A low BMR makes an animal more susceptible to cold. Hence, the relatively high plumage mass in the African compared to the European stonechat may be functionally linked to its relatively low BMR. Moult costs, calculated from the plumage masses and the differences in RMR inside and outside the moult period, tended to be higher in the European compared to the African stonechats. These data and an interspecific comparison of moult costs over various species of birds support the earlier notion by Lindström et al. (1993) that moult costs are more closely linked with BMR than with body mass or rate of moult. The relation between moult costs and BMR and the fact that the efficiency of moult is extremely low (3.8 and 6.4% for European and African stonechats, respectively) suggest that the maintenance of specific tissues necessary for moult is a large cost factor. Alternatively, impaired insulation during moult may necessitate an increased metabolic capacity which may be associated with an increased RMR.