Energy Expenditure and Adiposity in Nigerian and African‐American Women

Objective: Obesity is a prevalent condition in industrialized societies and is increasing around the world. We sought to assess the relative importance of resting energy expenditure (REE) and activity EE (AEE) in two populations with different rates of obesity. Methods and Procedures: Women of African descent between 18 and 59 years of age were recruited from rural Nigeria and from metropolitan Chicago. Total EE (TEE) was measured using the doubly labeled water (DLW) technique and REE by indirect calorimetry; AEE was calculated as the difference between TEE and the sum of REE plus a factor for the thermic effect of food. In the analyses all EE parameters were adjusted for body size using a regression method. Comparisons were made between the groups and associations between EE and adiposity examined. Results: A total of 149 Nigerian and 172 African‐American women completed the protocol. All body size measurements were lower in the Nigerian women. Adjusted TEE and REE were higher in the Nigerian cohort but adjusted AEE did not differ significantly. Adjustment for parity, seasonality, and recent illness did not modify mean AEE or adiposity. In neither cohort was there a meaningful association between measures of AEE and adiposity. Discussion: In these cohorts of women from very different environments, AEE did not differ significantly nor was it associated cross‐sectionally with adiposity. If generalizable, these findings suggest that reduction in AEE may have less of a role in the development of obesity than anticipated. The possibility remains that variation in type and duration of activity plays a role not captured by total AEE.     

Closing the gap between science and management of cold-water refuges in rivers and streams

Human activities and climate change threaten coldwater organisms in freshwater ecosystems by causing rivers and streams to warm, increasing the intensity and frequency of warm temperature events, and reducing thermal heterogeneity. Cold-water refuges are discrete patches of relatively cool water that are used by coldwater organisms for thermal relief and short-term survival. Globally, cohesive management approaches are needed that consider interlinked physical, biological, and social factors of cold-water refuges. We review current understanding of cold-water refuges, identify gaps between science and management, and evaluate policies aimed at protecting thermally sensitive species. Existing policies include designating cold-water habitats, restricting fishing during warm periods, and implementing threshold temperature standards or guidelines. However, these policies are rare and uncoordinated across spatial scales and often do not consider input from Indigenous peoples. We propose that cold-water refuges be managed as distinct operational landscape units, which provide a social and ecological context that is relevant at the watershed scale. These operational landscape units provide the foundation for an integrated framework that links science and management by (1) mapping and characterizing cold-water refuges to prioritize management and conservation actions, (2) leveraging existing and new policies, (3) improving coordination across jurisdictions, and (4) implementing adaptive management practices across scales. Our findings show that while there are many opportunities for scientific advancement, the current state of the sciences is sufficient to inform policy and management. Our proposed framework provides a path forward for managing and protecting cold-water refuges using existing and new policies to protect coldwater organisms in the face of global change.     

Warming up the system: higher predator feeding rates but lower energetic efficiencies

Predictions on the consequences of the rapidly increasing atmospheric CO₂ levels and associated climate warming for population dynamics, ecological community structure and ecosystem functioning depend on mechanistic energetic models of temperature effects on populations and their interactions. However, such mechanistic approaches combining warming effects on metabolic (energy loss of organisms) and feeding rates (energy gain by organisms) remain a key, yet elusive, goal. Aiming to fill this void, we studied the metabolic rates and functional responses of three differently sized, predatory ground beetles on one mobile and one more resident prey species across a temperature gradient (5, 10, 15, 20, 25 and 30 °C). Synthesizing metabolic and functional‐response theory, we develop novel mechanistic predictions how predator–prey interaction strengths (i.e., functional responses) should respond to warming. Corroborating prior theory, warming caused strong increases in metabolism and decreases in handling time. Consistent with our novel model, we found increases in predator attack rates on a mobile prey, whereas attack rates on a mostly resident prey remained constant across the temperature gradient. Together, these results provide critically important information that environmental warming generally increases the direct short‐term per capita interaction strengths between predators and their prey as described by functional‐response models. Nevertheless, the several fold stronger increase in metabolism with warming caused decreases in energetic efficiencies (ratio of per capita feeding rate to metabolic rate) for all predator–prey interactions. This implies that warming of natural ecosystems may dampen predator–prey oscillations thus stabilizing their dynamics. The severe long‐term implications; however, include predator starvation due to energetic inefficiency despite abundant resources.     

Mean power frequency and amplitude of the mechanomyographic and electromyographic signals during incremental cycle ergometry.

The purpose of this investigation was to determine the relationships for mechanomyographic (MMG) amplitude, MMG mean power frequency (MPF), electromyographic (EMG) amplitude, and EMG MPF versus power output during incremental cycle ergometry. Seventeen adults volunteered to perform an incremental test to exhaustion on a cycle ergometer. The test began at 50 W and the power output was increased by 30 W every 2 min until the subject could no longer maintain 70 rev min(-1). The MMG and EMG signals were recorded simultaneously from the vastus lateralis during the final 10 s of each power output and analyzed. MMG amplitude, MMG MPF, EMG amplitude, EMG MPF, and power output were normalized as a percentage of the maximal value from the cycle ergometer test. Polynomial regression analyses indicated that MMG amplitude increased (P<0.05) linearly across power output, but there was no change (P>0.05) in MMG MPF. EMG amplitude and MPF were fit best (P<0.05) with quadratic models. These results demonstrated dissociations among the time and frequency domains of MMG and EMG signals, which may provide information about motor control strategies during incremental cycle ergometry. The patterns for amplitude and frequency of the MMG signal may be useful for examining the relationship between motor-unit recruitment and firing rate during dynamic tasks.     

A Comparison of 2-Hydroxyestradiol and U-0521 (3'4'-Dihydroxy-2-methylpropiophenone, Upjohn) as In Situ and In Vitro Inhibitors of Tyro sine Hydroxylase

Abstract: Feedback inhibition of tyrosine hydroxylase by catechols was evaluated using in situ and in vitro enzyme assays. The three catechol compounds used were norepinephrine, 2-hydroxyestradiol, and 3'4'-dihydroxy-2-methylpropiophenone (U-0521, Upjohn); representing endogenous catechol-amines, catechol estrogens, and a synthetic catechol, respectively. The in situ experiments were performed with dissociated retinal cells from rats and with stationary phase adrenergic-like neuroblastoma cells (N1E-115). The catechol estrogen, 2-hydroxyestradiol, resembled the endogenous catecholamines in its potency to inhibit in vitro and in situ tyrosine hydroxylations with IC₅₀ values of 10 μM in vitro and 100 μM in situ. The drug U-0521, which has been used as an inhibitor of catechol- O -methyltransferase (COMT), was also found to be an inhibitor of tyrosine hydroxylase. Further, it was shown to be more potent than the natural catechols, both in vitro and in situ , with IC₅₀ values of 30–600 nM.     

A key phase in the recruitment dynamics of coral reef fishes: post-settlement transition

Synopsis Recent studies of recruitment dynamics in demersal fishes have placed major emphasis on presettlement mortality, and little on events bridging late larval and early juvenile periods. Observations on 68 taxa of Caribbean coral reef fishes before and during settlement revealed the existence of a distinct post-settlement life phase called the transition juvenile, associated with the act of recruitment. Transition juveniles were found as solitary individuals, in conspecific groups, or in heterospecific groups. The groups were either uniform or heterogenous in appearance. The complexity of the transition phase and its apparently widespread occurrence in coral reef fishes suggests that important aspects of population structure may be determined between settlement and first appearance as a full-fledged juvenile.     

Mechanomyographic and electromyographic responses to unilateral isometric training

The purpose of this investigation was to examine the effects of unilateral, isometric training of the forearm flexors on strength and the mechanomyographic (MMG) and electromyographic (EMG) responses of the biceps brachii in the trained and untrained limb at three joint angles. Seventeen adult females (mean age +/- SD = 21 +/- 2 years) were randomly assigned to a control (CTL; N=7) or a training (TRN; N=10) group. The TRN group performed isometric training of the non-dominant forearm flexors on a Cybex II Dynamometer at a joint angle such that the Cybex lever arm was positioned 60 degrees above the horizontal plane. The training consisted of 3 to 5 sets of 8, 6-second repetitions at 80% of maximal voluntary contraction 3 times per week for 8 weeks. The results indicated a significant increase in flexed arm circumference as well as isometric strength in the trained limb at all three joint angles. There were, however, no changes in MMG or EMG amplitude in the trained or untrained limb and no cross-training effect for strength or flexed arm circumference. These findings suggested that the increased strength may have been due to factors associated with hypertrophy, independent of neural adaptations in the biceps brachii. Furthermore, hypertrophy may have had counteractive effects on the MMG signal that could be responsible for the lack of a training-induced change in the MMG amplitude.     

Identification, isolation, and characterization of the 42-kilodalton major outer membrane protein (MompA) from Treponema pectinovorum ATCC 33768.

The major protein present in the isolated outer membrane of Treponema pectinovorum ATCC 33768, MompA, was identified, purified, and characterized. Immuno-gold electron microscopy, using anti-MompA serum, and cell fractionation experiments confirmed the localization of MompA to the outer membrane. MompA was determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis to have a molecular mass of 42 kDa when heat denatured, whereas native MompA formed a number of detergent-stable forms with molecular masses of 71, 76, and 83 kDa. A temperature of 60 degrees C was required to convert the native protein to the 42-kDa form. A number of detergents and chemical agents that are capable of breaking ionic and hydrogen bonds of proteins did not convert native MompA to the 42-kDa species. The native forms of the protein were resistant to the combined action of proteinase K, trypsin, and chymotrypsin, whereas the 42-kDa form of MompA was not. The N-terminal amino acid sequence of MompA was determined to be DVTVNINSRVRPVLYTT, and database searches did not identify any homology with known protein sequences. Amino acid compositional analysis showed the protein to be rich in proline and glycine, with these amino acids accounting for 28 and 13%, respectively, of the total amino acids. Antiserum raised against the major outer membrane protein of T. denticola GM-1 and ATCC 35405 did not cross-react with MompA, and antiserum raised against MompA did not react with any cellular components of Treponema denticola, Treponema vincentii, or Treponema socranskii. A major outer membrane protein similar in molecular mass to MompA was identified in eight clinical isolates of T. pectinovorum. The major outer membrane protein produced by four of the clinical isolates reacted strongly, by Western blotting, with anti-MompA serum, whereas proteins of the other strains did not.