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We have designed and utilized degenerate primers in the phylogenetic analysis of [FeFe] hydrogenase gene diversity in the
gut ecosystems of roaches and lower termites. H2 is an important free intermediate in the breakdown of wood by termite gut microbial communities, reaching concentrations
in some species exceeding those measured for any other biological system. The primers designed target with specificity the
largest group of enzymatic H domain proteins previously identified in a termite gut metagenome. “Family 3” hydrogenase sequences
were amplified from the guts of lower termites, Incisitermes minor, Zootermopsis nevadensis, and Reticulitermes hesperus, and two roaches, Cryptocercus punctulatus and Periplaneta americana. Subsequent analyses revealed that all termite and Cryptocercus sequences were phylogenetically distinct from non-termite-associated hydrogenases available from public databases. The abundance
of unique sequence operational taxonomic units (as many as 21 from each species) underscores the previously demonstrated physiological
importance of H2 to the gut ecosystems of these wood-feeding insects. The diversity of sequences observed might be reflective of multiple
niches that the enzymes have been evolved to accommodate. Sequences cloned from Cryptocercus and the lower termite samples, all of which are wood feeding insects, clustered closely with one another in phylogenetic
analyses to the exclusion of alleles from P. americana, an omnivorous cockroach, also cloned during this study. We present primers targeting a family of termite gut [FeFe] hydrogenases
and provide results that are consistent with a pivotal role for hydrogen in the termite gut ecosystem and point toward unique
evolutionary adaptations to the gut ecosystem. 相似文献
3.
Douglas L. Ballor Eric. T. Poehlman 《European journal of applied physiology and occupational physiology》1995,71(6):535-542
A meta-analysis was used to examine the independent and interactive effects of dietary restriction, endurance exercise training and gender on resting metabolic rate (RMR). Sixty different group means (covering 650 subjects) were identified from the scientific literature and subjected to meta-analysis techniques. Collectively (i.e., all groups combined), body weight loss was greater (P < 0.05) for men ( 18 kg) than for women ( 12 kg). There were no statistically significant exercise training or gender effects on RMR during weight loss. Collectively (i.e., all groups combined), dietary restriction resulted in a – 0.59 kJ min–1 ( – 12%) decrease in RMR (P < 0.05). When normalized to body weight, RMR was reduced by less than 2% (P < 0.05). These data suggest that exercise training does not differentially affect RMR during diet-induced weight loss. In addition, decreases in resting metabolism appear to be proportional to the loss of the metabolically active tissue. 相似文献
4.
Effect of dietary restriction and/or exercise on 23-h metabolic rate and body composition in female rats. 总被引:1,自引:0,他引:1
D L Ballor 《Journal of applied physiology》1991,71(3):801-806
This study examined the effects of three levels of dietary intake [ad libitum fed (AL), moderately severe (MSR), and severe restriction (SR)] and two levels of exercise [cage confinement (CC) and exercise training (E)] on 23-h resting metabolic rate (RMR) and body composition in 47 female Sprague-Dawley rats. At the end of the 9-wk study, the MSR and SR groups weighed approximately 81 and 61%, respectively, of the AL-CC group. RMR was depressed for the MSR and SR groups compared with the AL-CC group. This was true whether expressed on an absolute (ml/min) or relative (ml.min-1.kg-0.75) basis. On a relative basis, which accounts for changes caused by weight loss alone, the RMR decreased by approximately 12 and 19%, respectively, for the MSR and SR groups compared with the AL-CC group. Although E resulted in significant differences in fat mass, percent fat, percent water, and heart mass between the AL groups, there were no significant differences between E and CC groups at either the MSR or SR level of dietary intake for any of the variables measured (i.e., body composition, muscle mass, RMR). Thus E does not appear to affect the composition of lost weight or RMR during diet-induced weight loss for female rats of normal weight. 相似文献
5.
Exercise training elevates RMR during moderate but not severe dietary restriction in obese male rats
D L Ballor 《Journal of applied physiology》1991,70(5):2303-2310
This study examined the effects of 11 wk of exercise training (E) on resting O2 uptake (RMR) and the composition of diet-induced weight loss in obese male Sprague-Dawley rats (n = 48). The rats underwent one of three levels of dietary treatment: ad libitum (AL), moderate restriction (MR), and severe restriction (SR). Compared with AL-CC (cage confined; 647 +/- 13 g), the AL-E (84% of AL-CC), MR-CC (77%), MR-E (77%), SR-CC (63%), and SR-E (63%) groups were all reduced in body mass. At the MR level, E significantly reduced fat mass (FM; MR-CC 73 +/- 5, MR-E 45 +/- 5 g) and increased water mass (WM; MR-CC 307 +/- 5, MR-E 329 +/- 5 g) compared with CC. In contrast, no significant differences existed between the SR-CC and SR-E groups. Exercise training did not result in conservation of protein mass at any level of dietary intake. Exercise training significantly elevated RMR (on a kg0.75 basis) by approximately 7% for the AL-E and MR-E groups compared with their respective dietary counterparts. These findings may help reconcile the conflicting results present in the literature with respect to the effects of exercise training during diet-induced weight loss. That is, studies using relatively severe dietary restrictions are less likely to demonstrate exercise-induced changes in RMR, FM, and WM than those employing moderate dietary restrictions. 相似文献
6.
Background
Metabolically versatile soil bacteria Burkholderia cepacia complex (Bcc) have emerged as opportunistic pathogens, especially of cystic fibrosis (CF). Previously, we initiated the characterization of the phenylacetic acid (PA) degradation pathway in B. cenocepacia, a member of the Bcc, and demonstrated the necessity of a functional PA catabolic pathway for full virulence in Caenorhabditis elegans. In this study, we aimed to characterize regulatory elements and nutritional requirements that control the PA catabolic genes in B. cenocepacia K56-2. 相似文献7.
Jessica G Borger Sheila L Brown Lisa M Connor Adam NR Cartwright Annette M Dougall Ruud HP Wilbers Peter C Cook Lucy H Jackson‐Jones Alexander T Phythian‐Adams Cecilia Johansson Daniel M Davis Benjamin G Dewals Franca Ronchese Andrew S MacDonald 《The EMBO journal》2017,36(16):2404-2418
Type 2 inflammation is a defining feature of infection with parasitic worms (helminths), as well as being responsible for widespread suffering in allergies. However, the precise mechanisms involved in T helper (Th) 2 polarization by dendritic cells (DCs) are currently unclear. We have identified a previously unrecognized role for type I IFN (IFN‐I) in enabling this process. An IFN‐I signature was evident in DCs responding to the helminth Schistosoma mansoni or the allergen house dust mite (HDM). Further, IFN‐I signaling was required for optimal DC phenotypic activation in response to helminth antigen (Ag), and efficient migration to, and localization with, T cells in the draining lymph node (dLN). Importantly, DCs generated from Ifnar1?/? mice were incapable of initiating Th2 responses in vivo. These data demonstrate for the first time that the influence of IFN‐I is not limited to antiviral or bacterial settings but also has a central role to play in DC initiation of Th2 responses. 相似文献
8.
The utility of employing biogenerated ferric iron as an oxidant for the recycling of scrap metal has been demonstrated using continuously growing cells of the extremophilic organism Acidithiobacillus ferrooxidans. A ferric iron rich (70 mol%) lixiviant resulting from bioreactor based growth of A. ferrooxidans readily solubilized target scrap metal with the resultant generation of a leachate containing elevated ferrous iron levels and solubilized copper previously resident in the scrap metal. Recovery of the copper value was easily accomplished via a cementation reaction and the clarified leachate containing a replenished level of ferrous iron as growth substrate was shown to support the growth of A. ferrooxidans and be fully recyclable. The described process for scrap metal recycling and copper recovery was shown to be efficient and economically attractive. Additionally, the utility of employing the E(h) of the growth medium as a means for monitoring fluctuations in cell density in cultures of A. ferrooxidans is demonstrated. 相似文献
9.
We have completed a bioinformatic analysis of the hydrogenases encoded in the genomes of three termite gut treponeme isolates:
hydrogenotrophic, homoacetogenic Treponema primitia strains ZAS-1 and ZAS-2, and the hydrogen-producing, sugar-fermenting Treponema azotonutricium ZAS-9. H2 is an important free intermediate in the breakdown of wood by termite gut microbial communities, reaching concentrations
in some species exceeding those measured for any other biological system. The spirochetes encoded 4, 8, and 5 [FeFe] hydrogenase-like
proteins, identified by their H domains, respectively, but no other recognizable hydrogenases. The [FeFe] hydrogenases represented
many sequence families previously proposed in an analysis of termite gut metagenomic data. Each strain encoded both putative
[FeFe] hydrogenase enzymes and evolutionarily related hydrogen sensor/transducer proteins likely involved in phosphorelay
or methylation pathways, and possibly even chemotaxis. A new family of [FeFe] hydrogenases (FDH-Linked) is proposed that may
form a multimeric complex with formate dehydrogenase to provide reducing equivalents for reductive acetogenesis in T. primitia. The many and diverse [FeFe] hydrogenase-like proteins encoded within the sequenced genomes of the termite gut treponemes
has enabled the discovery of a putative new class of [FeFe] hydrogenase proteins potentially involved in acetogenesis and
furthered present understanding of many families, including sensory, of H domain proteins beyond what was possible through
the use of fragmentary termite gut metagenome sequence data alone, from which they were initially defined. 相似文献
10.
D L Ballor L J Tommerup D P Thomas D B Smith R E Keesey 《Journal of applied physiology》1990,68(6):2612-2617
The combined influence of exercise training and dietary restriction on daily energy expenditure was evaluated by exposing 48 male Sprague-Dawley rats to one of three food intake conditions [ad libitum (AL), moderately restricted (MR), or severely restricted (SR)] and to one of two exercise conditions [treadmill exercised (E) or cage confined (CC)]. After 10 wk of exercise and dietary restriction, the MR-CC and MR-E rats weighed 84 and 86%, respectively, of AL-CC, whereas the SR-CC and SR-E rats weighed 66 and 68% of AL-CC. Dietary restriction and subsequent weight loss produced significant reductions in both total and resting daily energy expenditure. Exercise partially reversed this effect, but the extent of this reversal diminished as the severity of dietary restriction was increased. These results raise the distinct possibility that inconsistencies in the current literature concerning the effects of exercise on whole body metabolism during periods of dietary restriction might be reconciled by an appreciation and an understanding of the influence that duration of exercise training and severity of food restriction have on this measure. 相似文献