Variation In Metabolic Activity Research Articles

Influence of Contaminants Mercury and PAHs on Somatic Indexes of the European Hake (Merluccius merluccius, L. 1758).

This research investigates the dynamics of contaminant exposure in European hake (Merluccius merluccius, L. 1758) from the Adriatic Sea (Central Mediterranean Sea) by examining the levels of total mercury (THg) and polycyclic aromatic hydrocarbons (PAHs) in the muscle fish tissues. The study explores the correlations between these pollutants and somatic indexes to identify the early warning signals of pollution and ecological effects. The levels of pollutants are influenced by season and sex. Lipids appear to have a minimal effect on the PAH levels, whereas they exhibit a positive correlation with mercury levels in the muscle. No significant relationships between the pollutants and condition indexes were observed, except for a positive correlation between THg and the gonadosomatic index, indicating a potential impact on the reproductive health of fish. In contrast, PAHs showed no meaningful correlation with condition indexes. Differences in contaminant accumulations and lipid levels between sexes reflect variations in metabolic activity, reproductive costs, and adaptive strategies to seasonal changes and energy demands. This study highlights the importance of long-term monitoring to improve pollution management, environmental conservation, and the protection of marine organisms' health.

Cellular senescence and metabolic reprogramming model based on bulk/single-cell RNA sequencing reveals PTGER4 as a therapeutic target for ccRCC

Clear cell renal cell carcinoma (ccRCC) is the prevailing histological subtype of renal cell carcinoma and has unique metabolic reprogramming during its occurrence and development. Cell senescence is one of the newly identified tumor characteristics. However, there is a dearth of methodical and all-encompassing investigations regarding the correlation between the broad-ranging alterations in metabolic processes associated with aging and ccRCC. We utilized a range of analytical methodologies, such as protein‒protein interaction network analysis and least absolute shrinkage and selection operator (LASSO) regression analysis, to form and validate a risk score model known as the senescence-metabolism-related risk model (SeMRM). Our study demonstrated that SeMRM could more precisely predict the OS of ccRCC patients than the clinical prognostic markers in use. By utilizing two distinct datasets of ccRCC, ICGC-KIRC (the International Cancer Genome Consortium) and GSE29609, as well as a single-cell dataset (GSE156632) and real patient clinical information, and further confirmed the relationship between the senescence-metabolism-related risk score (SeMRS) and ccRCC patient progression. It is worth noting that patients who were classified into different subgroups based on the SeMRS exhibited notable variations in metabolic activity, immune microenvironment, immune cell type transformation, mutant landscape, and drug responsiveness. We also demonstrated that PTGER4, a key gene in SeMRM, regulated ccRCC cell proliferation, lipid levels and the cell cycle in vivo and in vitro. Together, the utilization of SeMRM has the potential to function as a dependable clinical characteristic to increase the accuracy of prognostic assessment for patients diagnosed with ccRCC, thereby facilitating the selection of suitable treatment strategies.

Seasonal lipid dynamics of four Arctic bivalves: Implications for their physiological capacities to cope with future changes in coastal ecosystems.

The Arctic is exposed to unprecedented warming, at least three times higher than the global average, which induces significant melting of the cryosphere. Freshwater inputs from melting glaciers will subsequently affect coastal primary production and organic matter quality. However, due to a lack of basic knowledge on the physiology of Arctic organisms, it remains difficult to understand how these future trophic changes will threaten the long-term survival of benthic species in coastal habitats. This study aimed to gain new insights into the seasonal lipid dynamics of four dominant benthic bivalves (Astarte moerchi, Hiatella arctica, Musculus discors, and Mya truncata) collected before and after sea ice break-up in a high-Arctic fjord (Young Sound, NE Greenland). Total lipid content and fatty acid composition of digestive gland neutral lipids were analyzed to assess bivalve energy reserves while the fatty acid composition of gill polar lipids was determined as a biochemical indicator of interspecies variations in metabolic activity and temperature acclimation. Results showed a decrease in lipid reserves between May and August, suggesting that bivalves have only limited access to fresh organic matter until sea ice break-up. The lack of seasonal variation in the fatty acid composition of neutral lipids, especially essential ω3 fatty acids, indicates that no fatty acid transfer from the digestive glands to the gonads occurs between May and August, and therefore, no reproductive investment takes place during this period. Large interspecies differences in gill fatty acid composition were observed, which appear to be related to differences in species life span and metabolic strategies. Such differences in gill fatty acid composition of polar lipids, which generally influence metabolic rates and energy needs, may imply that not all benthic species will be equally sensitive to future changes in primary production and organic matter quality in Arctic coastal habitats.

GlucoCEST MRI for the Evaluation Response to Chemotherapeutic and Metabolic Treatments in a Murine Triple-Negative Breast Cancer: A Comparison with[18F]F-FDG-PET.

Triple-negative breast cancer (TNBC) patients have usually poor outcome after chemotherapy and early prediction of therapeutic response would be helpful. [18F]F-FDG-PET/CT acquisitions are often carried out to monitor variation in metabolic activity associated with response to the therapy, despite moderate accuracy and radiation exposure limit its application. The glucoCEST technique relies on the use of unlabelled D-glucose to assess glucose uptake with conventional MRI scanners and is currently under active investigations at clinical level. This work aims at validating the potential of MRI-glucoCEST in monitoring the therapeutic responses in a TNBC tumor murine model. Breast tumor (4T1)-bearing mice were treated with doxorubicin or dichloroacetate for 1week. PET/CT with [18F]F-FDG and MRI-glucoCEST were performed at baseline and after 3 cycles of treatment. Metabolic changes measured with [18F]F-FDG-PET and glucoCEST were compared and evaluated with changes in tumor volumes. Doxorubicin-treated mice showed a significant decrease in tumor growth when compared to the control group. GlucoCEST imaging provided metabolic response after three cycles of treatment. Conversely, no variations were detected in [18F]F-FDG uptake. Dichloroacetate-treated mice did not show any decrease either in tumor volume or in tumor metabolic activity as assessed by both glucoCEST and [18F]F-FDG-PET. Metabolic changes during doxorubicin treatment can be predicted by glucoCEST imaging that appears more sensitive than [18F]F-FDG-PET in reporting on therapeutic response. These findings support the view that glucoCEST may be a sensitive technique for monitoring metabolic response, but future studies are needed to explore the accuracy of this approach in other tumor types and treatments.

CRAGE-mediated insertion of fluorescent chromosomal markers for accurate and scalable measurement of co-culture dynamics in Escherichia coli.

Monitoring population dynamics in co-culture is necessary in engineering microbial consortia involved in distributed metabolic processes or biosensing applications. However, it remains difficult to measure strain-specific growth dynamics in high-throughput formats. This is especially vexing in plate-based functional screens leveraging whole-cell biosensors to detect specific metabolic signals. Here, we develop an experimental high-throughput co-culture system to measure and model the relationship between fluorescence and cell abundance, combining chassis-independent recombinase-assisted genome engineering (CRAGE) and whole-cell biosensing with a PemrR-green fluorescent protein (GFP) monoaromatic reporter used in plate-based functional screening. CRAGE was used to construct Escherichia coli EPI300 strains constitutively expressing red fluorescent protein (RFP) and the relationship between RFP expression and optical density (OD600) was determined throughout the EPI300 growth cycle. A linear equation describing the increase of normalized RFP fluorescence during deceleration phase was derived and used to predict biosensor strain dynamics in co-culture. Measured and predicted values were compared using flow cytometric detection methods. Induction of the biosensor lead to increased GFP fluorescence normalized to biosensor cell abundance, as expected, but a significant decrease in relative abundance of the biosensor strain in co-culture and a decrease in bulk GFP fluorescence. Taken together, these results highlight sensitivity of population dynamics to variations in metabolic activity in co-culture and the potential effect of these dynamics on the performance of functional screens in plate-based formats. The engineered strains and model used to evaluate these dynamics provide a framework for optimizing growth of synthetic co-cultures used in screening, testing and pathway engineering applications.

Cytochrome P450 2D6 polymorphism in eastern Indian population.

OBJECTIVES:Cytochrome P450 2D6 (CYP2D6) enzyme metabolizes a quarter of prescription drugs. Polymorphisms of CYP2D6 gene and resultant phenotypic variations in metabolic activity have been described in various populations. We assessed the prevalence of CYP2D6 activity phenotypes, employing dextromethorphan (DXM) as probe drug in subjects with at least two parental generations residing in eastern India.MATERIALS AND METHODS:Unrelated healthy subjects took 60 mg DXM after fasting overnight. Blood samples were collected 3 h after dosing and plasma separated. DXM and its primary metabolite dextrorphan (DXT) were measured by liquid chromatography with tandem mass spectrometry. The DXM-to-DXT metabolic ratio (MR) was obtained for each subject. Histogram of MR values suggested bimodal distribution. A polynomial regression equation derived through probit analysis was solved to identify the antimode of the MR values. Subjects with log(MR) < antimode were extensive metabolizers (EMs). Log(MR) ≥ antimode indicated poor metabolizers (PMs).RESULTS:We evaluated the results from 97 participants. The median MR was 0.209 (interquartile range: 0.090–0.609), while the antimode for MR was 3.055. From these, it was inferred that three subjects were PMs, while the rest were EMs. CYP2D6 polymorphism prevalence is low (3.09%; 95% confidence interval: 0.35%–6.54%) in the population of eastern India and matches the prevalence in other zones of the country.CONCLUSIONS:Differences in CYP2D6 activity has treatment implications and may lead to adverse events or therapeutic failure. Phenotyping of subjects receiving CYP2D6 metabolized drugs may help clinicians personalize treatment and avert adverse drug-drug interactions. However, the frequency of the PM phenotype is low in India, and routinely phenotyping for CYP2D6 activity will not be cost-effective. We cannot recommend it at this stage.

Juvenile divergence in adaptive traits among seven sympatric fish ecomorphs arises before moving to different lacustrine habitats.

Identifying the mechanisms initiating sympatric diversification in vertebrates has remained a conceptual challenge. Here, we analyse an assemblage of sympatric charr (Salvelinus malma) morphs from landlocked Lake Kronotskoe basin as a model to uncover the divergence pathways in freshwater fishes during the early life history stages. All morphs have distinct developmental biology, but a similar developmental rate retardation compared to the ancestor. Our study reveals that adult morphological differences, which acquire functionality at maturation, originate in the early juvenile stages due to heterochrony in skeletogenesis and allometric changes triggered by variation in metabolic activity. The craniofacial differences among the morphs result from asynchronous development of several skeletal modules. The accelerated ossification of teeth-armed bones occurs in predatory feeding morphs, whereas cranial cover ossification is promoted in benthivorous morphs. These contrasting growth patterns have led to seven phenotypes that span a range far beyond the ancestral variability. The most distinct morphs are a riverine spawning, epilimnetic predator and a lacustrine spawning, profundal benthic feeder. Taken together, we argue that the adaptive morphological differentiation in these sympatric freshwater fishes is driven by diverging patterns in ossification rate and metabolic activity against a background of uneven somatic growth. This divergence is primarily associated with basic environmental differences on the nursery grounds that might be unrelated to resource use. This nonheritable phenotype divergence is then exposed to natural selection that could result in further adaptive genetic changes.

Phylogenomic analysis of integral diiron membrane histidine motif-containing enzymes in ciliates provides insights into their function and evolutionary relationships

The Integral Membrane Histidine Motif-containing Enzymes (IMHME) are a class of binuclear non-heme iron proteins widely distributed among prokaryotes and eukaryotes. They are characterized by a conserved tripartite motif consisting of eight to ten histidine residues. Their known function is the activation of the dioxygen moiety to serve as efficient catalysts for reactions of hydroxylation, desaturation or reduction. To date most studies on IMHME were carried out in metazoan, phototrophic or parasitic organisms, whereas genome-wide analysis in heterotrophic free living protozoa, such as the Ciliophora phylum, has not been undertaken. In the seven fully sequenced genomes available we retrieved 118 putative sequences of the IMHME type, albeit with large differences in number among the ciliates: 11 sequences in Euplotes octocarinatus, 7 in Ichthyophthirius multifiliis, 13 in Oxytricha trifallax, 18 in Stylonychia lemnae, 25 in Tetrahymena thermophila, 31 in Paramecium tetraurelia and 13 in Pseudocohnilembus persalinus.The pool of putative sequences was classified in 16 orthologous groups from which 11 were related to fatty acid desaturase (FAD) and 5 to the fatty acid hydroxylase (FAH) superfamilies. Noteworthy, a large diversity on the number and type of FAD / FAH proteins were found among the ciliates, a feature that, in principle, may be attributed to peculiarities of the evolutionary process, such as gene expansion and reduction, but also to horizontal gene transfer, as we demonstrate in this work. We identified twelve putative enzymatic activities, from which four were newly assigned activities: sphingolipid Δ4-desaturase, ω3/Δ15 fatty acid desaturase, a large group of alkane 1-monooxygenases, and acylamide-delta-3(E)-desaturase, although unequivocal allocation would require additional experiments. We also combined the phylogenetics analysis with lipids analysis, thereby allowing the detection of two enzymatic activities not previously reported: a C-5 sterol desaturase in P. tetraurelia and a delta-9 fatty acid desaturase in Cohnilembus reniformis.The analysis revealed a significant lower number of FAD’s sequences in the spirotrichea ciliates than in the oligohymenophorea, emphasizing the importance of fatty acids trophic transfer among aquatic organisms as a source of variation in metabolic activity, individual and population growth rates, and reproduction.

Challenges in CYP2D6 Phenotype Assignment from Genotype Data: A Critical Assessment and Call for Standardization

The cytochrome P450 2D6 (CYP2D6) enzyme contributes to the metabolism and/or bioactivation of approximately 25% of clinically used drugs. The CYP2D6 gene locus is highly polymorphic and complex, and variants within this gene locus affect CYP2D6 enzymatic function resulting in a wide range of metabolic activity from little to no activity to ultrarapid metabolism. For many of the drugs metabolized by CYP2D6, the variation in metabolic activity is one of the most important factors responsible for interindividual drug response. Therefore, determining an individual's CYP2D6 phenotype, or metabolic status, will help identify individuals that may benefit from a change in drug or drug dosage. Genotype analysis has become the method of choice to predict a person's metabolic status. Numerous reference laboratories now offer CYP2D6 genotyping; however, there can be substantial differences in the number of genetic variants interrogated as well as test interpretation. Furthermore, there is no standardized process of how a CYP2D6 genotype result is translated into a phenotype assignment. This review summarizes the complexity of CYP2D6 genotyping and highlights the major challenges for phenotype classification. We call for the implementation of a universally accepted system for CYP2D6 phenotype assignment to promote consistency of test interpretation among reference laboratories and medical institutions. We propose a system that utilizes the CYP2D6 activity score system to place individuals into a continuum of activity scores - rather than using the traditional poor, intermediate, extensive and ultra-rapid metabolizer categorizations - and directly translating activity scores into clinically actionable recommendations.

Generation of red blood cells in vitro: monitoring the process for improved efficiency

Generation of red blood cells in vitro: monitoring the process for improved efficiency

Seasonal variations in metabolic activity of spermatozoa and antioxidant enzyme activity in the reproductive tract fluids of wild boar/domestic pig hybrids

Seasonal variations in metabolic activity of spermatozoa and antioxidant enzyme activity in the reproductive tract fluids of wild boar/domestic pig hybrids

Risk Statification of Follicular Lymphomas Using Two Independent Prognostic Factors: Lymphoma Cell Size Assessment by Flow Cytometry and FDG PET Based Metabolic Activity

AbstractAbstract 5098 Introduction:Follicular Lymphoma (FL) comprises of 20–30% of Non-Hodgkin’s Lymphomas. It is the most common lymphoma with varied clinical aggressiveness, depending on morphological grading on histology. The prognosis of FL is heterogeneous. Therefore therapeutic options for FL are increasingly becoming more risk-adopted. Pathologically, FL has been graded into grade 1–2 (FL1–2) and grade 3 (FL3) by visual counting or estimating the absolute number of centroblasts in neoplastic follicles. Recent studies found that the average tumor cell size of FL is highly variable, but is consistently reproducible, achieved by an objective measurement using flow cytometry. A significant variation in metabolic activity has also been observed in FL studied by PET scan. The purpose of this study was to investigate a new risk stratification method for FL using a combined criterion of Flow cytometry based cell size of FL cells and metabolic activity based on FDG PET scan to further evaluate their prognostic values. Materials and Methods:Retrospective study of 64 patients (25 males and 39 females with median age of 61 years), diagnosed with FL between 2006 –2010 in Beaumont Health System with proper HIC approval was performed. 44 cases were graded morphologically into low risk (FL 1–2) and 20 into high risk (FL 3), based on current WHO classification. The average tumor cell size was measured based flow cytometric analysis of the relative forward scatters (FSC) of tumor cells relative to that of internal T-cells in the lymphoma tissue. The metabolic activity was measured as in maximal standardized uptake value (SUV max) of the involved lymph node by PET scan based F-18 FDG uptake. The SUV was normalized to a glucose level of 100 using the formula: SUV100={[100 mg/dl]/[glc]}g where g=[-0. 5] from our prior publication and [Glc] was the glucose level of the patient recorded at the time of PET scan. The difference of average lymphoma cell size between grade 1–2 (FL 1–2, indolent) and grade 3 (FL 3, aggressive) was compared with Student t test. The difference of size distribution between FL with low SUV100 and FL with high SUV100 were compared with Chi square and Kappa tests. A two-tail p-value less than 0. 05 was considered significant in all tests. FSC and Metabolic activity were cross tabbed and correlated using cut off values determined by discriminant analysis. Results:The FSC of B-cells were significantly lower in low grade FL than that in high grade FL (p=0. 00002). In contrast, FSC of residual T-cells in low grade FL and high grade FL were about the same (p=0. 2). Average lymphoma cell size of the low risk group (relative FSC of −15, range of −83 to 153) was significantly smaller than that of high risk group(relative FSC of 92, range of −32 to 243), (P<0. 0005)(figure 1). Using a cut off value FSC= −18 from discriminant analysis, and group them into aggressive and indolent FL, there was significant difference in metabolic activity (SUV 100) between the lymphoma with small and large tumor cell sizes (p=0. 021, by Chi-Square test)(figure 2). Combining these two objective independent measurements could accurately place low risk FL into observation with 95% confidence. Conclusion:The significance of average lymphoma cell size identified by FSC in this study between FL grade 3 and grade 1–2 validate potential utility of flow cytometry in grading FL in refining the grading because the measurement of average lymphoma cell size by flow cytometry it is more reproducible, objective, and easy to use than manual counting centroblasts microscopically. Since increased metabolic activity is often associated with more aggressive clinical behavior, combining tumor cell size by flow cytometry and metabolic activity by FDG PET imaging can potentially serve as an independent criterion in risk stratification and better grading of FL. Further clinical correlation is in progress. [Display omitted] [Display omitted] Disclosures:No relevant conflicts of interest to declare.

FMRI response to blue light delivery in the naïve brain: Implications for combined optogenetic fMRI studies

The combination of optogenetics and functional magnetic resonance imaging (fMRI) is referred to as opto-fMRI. Optogenetics utilises genetic engineering to introduce light sensitive actuator proteins into cells. Functional MRI (fMRI) is a specialist form of magnetic resonance imaging concerned with imaging changes in blood flow and oxygenation, linked to regional variation in metabolic activity, in the brain. This study describes a methodological concern regarding the effects of light delivery into the brain for the purposes of opto-fMRI. We show that blue light delivery to the naïve rat brain causes profound fMRI responses, despite the absence of optogenetic activation. We demonstrate that these fMRI responses are dependent upon laser power and show that the laser causes significant heating. We identify how heating impacts upon the MR signal causing NMR frequency shifts, and T1 and T2* changes. This study brings attention to a possible confounder which must be taken into account when opto-fMRI experiments are designed.

Characterization of Human Endplate Biopsies: Preliminary Results on Cellular Composition, Metabolic Activity and Interactions with Disk Cells

Introduction Tissue alterations that result in an impaired endplate (EP) permeability are assumed to play a crucial role in the pathogenesis of intervertebral disk (IVD) degeneration. Therefore, disturbance of endplate permeability is one of the main problems that need to be solved for successful disk tissue engineering. However, the biological mechanisms underlying these alterations are poorly understood. To shed light on this aspect, a standardized analysis of EP structure and cellular composition is essential to understand the degeneration processes. Purpose of this study was the development of standardized protocols for a descriptive characterization of EP samples by histology, transmission electron microscopy (TEM), analysis of differentiation and metabolic activity of EP cells. In first preliminary experiments we also aimed to detect possible interactions of the EP with disk cells of the same donor patients in a bioassay with EP-conditioned media. The suitability of these methods for EP characterization and possible correlations with degenerative alterations is discussed. Materials and Methods Cartilaginous endplates obtained during spine surgery of total 27 human donors underwent the following procedures: (1) isolation of endplate cells, in vitro expansion and characterization of chondrogenic differentiation in 3D pellet cultures ( n = 6), (2) preparation of standardized EP-sections for histological and ultrastructural analyses ( n = 8), and (3) preparation of standardized endplate punches that were incubated for 24 hours in serum-free culture medium followed by determination of metabolic activity of endplate cells by MTT-test ( n = 13) and further analysis of conditioned media (CM) in a bioassay with NP cells of the same donor ( n = 2). Pellet cultures of EP cells were characterized for matrix protein expression by Alcian blue staining. Influences of CM on gene expression of matrix proteins, matrix degrading enzymes, and inflammation factors by NP cells were determined. Results Differentiation of endplate cells in pellet cultures varied strongly not only between the six individual donors, but also in different disk levels of the same patient. Part of the samples exhibited a very low proteoglycan production whereas others were strongly positive in the Alcian blue staining intensity suggesting high variations in the differentiation capacity of EP cells. Histological examination of the endplate samples allowed a characterization of both the endplates and an observation of the adjacent structures as the very thin endplate layer could not be clearly separated from adjacent tissue structures. High variations between tissue samples from different donors could be found. TEM images showed signs of degeneration both in the matrix and the EP cells whereas higher numbers of apoptotic cells and matrix degradation products could be found in stronger degenerated tissue samples. Standardized EP punches that were cultured for 24 hours in DMEM and incubated for 4 hours with MTT showed different staining intensities suggesting donor-specific variations in metabolic activity of EP cells. In first two experiments with CM of EP samples, a dose-dependent upregulation of inflammation-factors and matrix metalloproteinases (Interleukins IL-1β, IL-6, IL-8, MMP-3, and MMP13) by NP-cells of the same donors could be detected. The extent of this effect differed strongly between the two patients with different degeneration degree. Conclusion The present results suggest that a combination of different methods allows the characterization of EP tissue and possible interactions with the adjacent disk tissue. As the cartilaginous EP itself is very thin and with low cellularity, isolation of an almost homogeneous EP population is very difficult and the cell yield is very poor. Therefore, methods that directly analyze the cells in situ for example by laser capture micro-dissection might be more suitable to determine the gene expression profile of EP cells. Analysis of metabolic activity of standardized EP punches by MTT test is a promising approach provided that the samples are standardized with regard to diameter and height with no adjacent other tissue regions. TEM investigation is appropriate to investigate cellular details, but also with this method, the poor cellularity of EP tissue is a challenge. A very promising approach is the analysis of CM in a bioassay with NP cells of the same donor that allows the detection of possible interactions between both tissue areas. In ongoing investigations, we analyze higher numbers of EP samples with different degrees of degeneration to enable a correlation between the biological and clinical data of the patients. For this purpose, analyses of nondegenerated control samples are essential. In summary, all these methods together allow a holistic view on the mechanisms that contribute to the morphological and pathophysiological changes of the EP and potential interaction with the adjacent disk tissue. Acknowledgement Part of this research work was supported by the EU framework 7 project Geneodisc (FP7, 2007–2013) under grant agreement no. HEALTH-F2-2008-201626. I confirm having declared any potential conflict of interest for all authors listed on this abstract Yes Disclosure of Interest None declared

Variability of heterotrophic metabolism in small stream corridors of an early successional watershed

[1] Metabolic activity in stream corridors is regulated by a complex combination of factors that are difficult to disentangle in mature ecosystems. Chicken Creek in Germany, an experimentally created watershed in an early successional stage, offers the opportunity to assess the spatiotemporal variation in metabolic activity in a simplified system. We measured microbial respiration in soils and sediments along the hydrologic flow path from upland terrestrial to ephemeral to perennial sites of three stream corridors. Dry soils and sediments were rewetted before respiration measurements to mimic periods of activity during and after rainfall. Respiration rates and organic matter contents of soil and sediment were generally low. The presence of algae and accretion of vascular plant fragments in the perennial stream reaches increased respiration rates, pointing to the importance of particulate organic matter. Contrary to expectation, respiration rates of rewetted soil and sediment from dry stream channels were similar to rates measured with sediments collected in the perennial channel sections. This suggests that permanent water availability was not a main factor determining metabolic potential in the early successional Chicken Creek watershed. Carbon turnover in perennial channels was fourfold to eightfold higher than in ephemeral channels and terrestrial sites, as water was permanently available. However, this magnitude was insufficient for perennial channels to compensate for the large surface area of terrestrial soils: extrapolated to a year and the whole watershed, stream channels contributed only 5% to total carbon turnover, 95% being due to soils during and after rainfall events.

Developmental Stability in Chickens Local to Warm Climatic Region 2. Variation in Blood Metabolites Due to Genetic Selection and Crossing

An experiment was conducted to assess the variation in blood metabolic constituents in a local chicken line (CE1) selected five generations for increased 6-wk body weight. Also, line CE1 was reciprocally crossed with a Slow-Growing Commercial Broiler Strain (SGB). The local genetic control line (CRB) was used for genetic comparison. No significant differences were observed in the blood levels of total proteins, albumin, globulin and Albumin/Globulin (A/G) ratio among lines CE1 and CRB in both parental (P) and progeny (F1) generations. In P generation, total protein levels of 2.22 and 2.16 g/dl were obtained for lines CE1 and CRB and were significantly higher than 1.78 g/dl for strain SGB. Line CE1 had triglyceride level of 178.76 mg/dl which was significantly higher than 122.13 mg/dl for line CRB. Similar trend for the blood lipid metabolites were obtained in F1 generation. Sex variation in body weight although was obvious, the selection pressure on sex variation in metabolic activity was not existed. Significant heterosis estimates of -22.56 and 5.0% were obtained for the levels of total lipids and cholesterol. The heterosis estimates in the levels of total proteins, albumin, globulin, A/G ratio and triglycerides were -23.71, 9.94, -33.66, 14.97 and -3.63%, but lacked significance. Although heterosis estimates were mostly insignificant, they indicated that the metabolic activity could be drastically changed by crossing. The drastic change in the metabolic activity was too early to be noticeable in a short-term selection program. Selection pressure was more obvious in lipid metabolites, particularly triglycerides, than in protein metabolites. Highly moderate negative and significant correlation coefficient was obtained between globulin level and cholesterol level. The variable correlation relationships among blood metabolites and the insignificant correlations between blood metabolites and body weights did not reflect the continuous metabolic and tissue remodeling associated with growth. This could be due to the small size that characterizes local chickens of warm regions or the shortness of selection scheme that did not result in an obvious change in the metabolic activity.

Seasonality of metabolic capacity in resident tropical birds

Temperature seasonality drives variation in metabolic activity of temperate zone resident bird species. Contrary to predictions from life history theory, energetic capacity is not maximal during the breeding season, but is instead highest during winter when survival is the animal's primary concern. Tropical residents do not experience the large annual temperature cycles characteristic of temperate zones. Reflecting their relatively constant environment, we predicted that tropical birds would either: 1) show no annual variation in metabolic capacity, or 2) show increased metabolic capacity during the breeding season. We collected data at the Smithsonian Tropical Research Institute station in Bocas del Toro, Republic of Panama (9°N) during either February (winter) or June (summer) on several avian species including several taxonomic groups and dietary preference. In all cases, birds measured in winter had lower metabolic capacity than the same species measured in summer. We conclude that although breeding efforts are less intense in tropical birds, that they are able to increase metabolic effort toward breeding over maintenance during the rest of the year.

Emotions beyond the laboratory: Theoretical fundaments, study design, and analytic strategies for advanced ambulatory assessment

Questionnaire and interview assessment can provide reliable data on attitudes and self-perceptions on emotion, and experimental laboratory assessment can examine functional relations between stimuli and reactions under controlled conditions. On the other hand, ambulatory assessment is less constrained and provides naturalistic data on emotion in daily life, with the potential to (1) assure external validity of laboratory findings, (2) provide normative data on prevalence, quality and intensity of real-life emotion and associated processes, (3) characterize previously unidentified emotional phenomena, and (4) model real-life stimuli for representative laboratory research design. Technological innovations now allow for detailed ambulatory study of emotion across domains of subjective experience, overt behavior and physiology. However, methodological challenges abound that may compromise attempts to characterize biobehavioral aspects of emotion in the real world. For example, emotional effects can be masked by social engagement, mental and physical workloads, as well as by food intake and circadian and quasi-random variation in metabolic activity. The complexity of data streams and multitude of factors that influence them require a high degree of context specification for meaningful data interpretation. We consider possible solutions to typical and often overlooked issues related to ambulatory emotion research, including aspects of study design decisions, recording devices and channels, electronic diary implementation, and data analysis.

Temporal and spatial metabolic rate variation in the Antarctic springtail Gomphiocephalus hodgsoni

Spatial and temporal environmental variation in terrestrial Antarctic ecosystems are known to impact species strongly at a local scale, but the ways in which organisms respond (e.g. physiologically, behaviourally) to such variation are poorly understood. Further, very few studies have attempted to assess inter-annual variability of such responses.Building on previous work demonstrating intra-seasonal variation in standard metabolic rate in the springtail Gomphiocephalushodgsoni, we investigated variation in metabolic activity of G. hodgsoni across two austral summer periods at Cape Bird, Ross Island. We also examined the influence of spatial variation by comparing metabolic rates of G. hodgsoni at Cape Bird with those from two other isolated continental locations within Victoria Land (Garwood and Taylor Valleys).We found significant differences between metabolic rates across the 2 years of measurement at Cape Bird. In addition, standard metabolic rates of G. hodgsoni obtained from Garwood and Taylor Valleys were significantly higher than those at Cape Bird where habitats are comparable, but environmental characteristics differ (e.g. microclimatic temperatures are higher).We discuss potential underlying causes of these metabolic rate variation patterns, including those related to differences among individuals (e.g. physiological and genetic differences), locations (e.g. habitat quality and microclimatic regime differences) and populations (e.g. acclimation differences among G. hodgsoni populations in the form of metabolic cold adaptation (MCA)).

Determinants of the rate of nicotine metabolism and effects on smoking behavior

Studies on cytochrome P450 (CYP) 2A6 suggest that genotype affects the rate of nicotine metabolism and, consequently, cigarette consumption. However, known alleles of CYP2A6 associated with fast or slow metabolism are relatively uncommon, and there remains considerable variation in metabolic activity among those with presumed wild-type CYP2A6 alleles, suggesting that other genetic or environmental factors also influence the rate of nicotine metabolism. We investigated determinants of the rate of nicotine metabolism and effects on smoking behavior in a United Kingdom cohort who participated in a placebo-controlled trial of smoking cessation via nicotine replacement therapy. Those who continued to smoke cigarettes at the 8-year follow-up formed our study group (N = 545). The ratio of the nicotine metabolite trans-3'-hydroxycotinine to cotinine in plasma was used as an index of CYP2A6 activity and thus as a marker of the rate of nicotine metabolism. The nicotine metabolite ratio was associated with sex (P < .0001), CYP2A6 genotype (*1B, *2, *4, *9, and *12) (P < .0001), CYP2B6 haplotype (*4-dominant) (P = .02), plasma nicotine concentration (P < .0001), and age (P = .02) but was not associated with dependence score (P > .20). The ratio also predicted the number of cigarettes smoked at will per day, although the association was weak (F(1, 492) = 4.05, P = .04). In this cohort the rate of nicotine metabolism is related to age, sex, CYP2A6 genotype, and CYP2B6 genotype and may affect the level of tobacco consumption.