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41.
This study was conducted with 16 male growing pigs (eight pigs with an end-to-end ileo-rectal anastomosis, eight intact pigs) to investigate in metabolic trials the influence of different pre-, pro-, and synbiotics on the precaecal and faecal digestibility of thiamin, riboflavin, pantothenic acid and biotin. A basic experimental diet was supplemented with either pre-, pro-, or synbiotic additives as follows: lactulose (2%), inulin (2%), mannanoligosaccharides (0.3%), Enterococcus faecium DSM 10663 (8 x 10(9) cfu/kg), Enterococcusfaecium DSM 7134 (5 x 10(8) cfu/kg), inulin + Enterococcusfaecium DSM 10663, mannanoligosaccharides + Enterococcus faecium DSM 7134. The precaecal and faecal digestibilities of the investigated B-vitamins were not affected significantly by the administered pre-, pro-, and synbiotics independent of the application period. A higher faecal vitamin excretion vs. the precaecal indicated that thiamin and biotin were synthesized in the colon. On the contrary, for riboflavin and pantothenic acid a higher precaecal vitamin flow compared to the faecal excretion was detected indicating to a certain extent an absorption in the colon. 相似文献
42.
In seasonal environments with limited time and energy resources, double‐brooded birds face trade‐offs in the timing of their two reproductive attempts and in the effort allocated to the first and the second broods. In the Barn Swallow Hirundo rustica a long care period for the first brood enhances the survival of first‐brood chicks, but also delays the start of the second brood, which in turn reduces the survival prospects of second‐brood chicks. Probably as a response to this trade‐off, double‐brooded Barn Swallows reduce the period of post‐fledging care for first‐brood fledglings. By radiotracking whole families, we investigated the determinants of this behaviour and its consequences for the survival of the first‐brood fledglings. The end of the females’ investment in post‐fledging care of the first brood was related to the beginning of egg synthesis for the second clutch. With the start of egg synthesis, females significantly reduced provisioning rates to the first‐brood fledglings to less than one‐fifth of the previous rates, while the proportion of time they spent foraging remained high. Assuming that the females’ foraging success was constant, we conclude that their energy income was allocated to egg production rather than fledgling provision. Males did not compensate for the females’ reduced feeding rates. Thus the start of egg production for the second clutch had a marked effect on the quantity of food received by first‐brood fledglings. In parallel with the changes in parental behaviour and provisioning rates, we observed a marked drop in the daily survival rate of first‐brood chicks. These results support the hypothesis that females face a strong trade‐off in the allocation of energy to subsequent broods. Energy allocation to a second clutch involves a cost in terms of reduced provisioning, and as a result the survival of first‐brood chicks is compromised. This is probably outweighed by the improved success of an early second brood. 相似文献
43.
Richter E Branner B 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2002,778(1-2):49-62
Haemoglobin (Hb) adducts from aromatic amines (AAs) are well established biomarkers of exposure. Tobacco smoking and occupational exposure are major sources of AA Hb adducts. The origin of background levels in non-smokers and non-occupationally exposed humans are largely unknown. Here we examine the determination of AA Hb adducts, focussing on the analytical strategies for Hb isolation, removal of unbound AAs from Hb solutions, hydrolysis of the Hb bound AAs, extraction, preconcentration, clean-up and derivatisation of the free amines for determination by gas chromatography-mass spectrometry. Finally, a detailed summary of available results on the determination of AA Hb adducts is given. 相似文献
44.
Howe GT; Bucciaglia PA; Hackett WP; Furnier GR; Cordonnier-Pratt MM; Gardner G 《Molecular biology and evolution》1998,15(2):160-175
The phytochrome photoreceptors play important roles in the photoperiodic
control of vegetative bud set, growth cessation, dormancy induction, and
cold-hardiness in trees. Interestingly, ecotypic differences in
photoperiodic responses are observed in many temperate- zone tree species.
Northern and southern ecotypes of black cottonwood (Populus trichocarpa
Torr. & Gray), for example, exhibit marked differences in the timing of
short-day-induced bud set and growth cessation, and these responses are
controlled by phytochrome. Therefore, as a first step toward determining
the molecular genetic basis of photoperiodic ecotypes in trees, we
characterized the phytochrome gene (PHY) family in black cottonwood. We
recovered fragments of one PHYA and two PHYB using PCR-based cloning and by
screening a genomic library. Results from Southern analyses confirmed that
black cottonwood has one PHYA locus and two PHYB loci, which we arbitrarily
designated PHYB1 and PHYB2. Phylogenetic analyses which included PHY from
black cottonwood, Arabidopsis thaliana and tomato (Solanum lycopersicum)
suggest that the PHYB/D duplications in these species occurred
independently. When Southern blots were probed with PHYC, PHYE, and PHYE
heterologous probes, the strongest bands that we detected were those of
black cottonwood PHYA and/or PHYB. These results suggest that black
cottonwood lacks members of the PHYC/F and PHYE subfamilies. Although black
cottonwood could contain additional PHY that are distantly related to known
angiosperm PHY, our results imply that the PHY family of black cottonwood
is less complex than that of other well-characterized dicot species such as
Arabidopsis and tomato. Based on Southern analyses of five black cottonwood
genotypes representing three photoperiodic ecotypes, substantial
polymorphism was detected for at least one of the PHYB loci but not for the
PHYA locus. The novel character of the PHY family in black cottonwood, as
well as the differences in polymorphism we observed between the PHYA and
PHYB subfamilies, indicates that a number of fundamental macro- and
microevolutionary questions remain to be answered about the PHY family in
dicots.
相似文献
45.
46.
Floyd Matthew Mizuyama Masaru Obuchi Masami Sommer Brigitte Miller Mark GR Kawamura Iori Kise Hiroki Reimer James D. Beger Maria 《Coral reefs (Online)》2020,39(5):1361-1376
Coral Reefs - Global warming is leading to range shifts of marine species, threatening the structure and functioning of ecological communities and human populations that rely on them. The largest... 相似文献
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48.
Mice of the TO Swiss strain received diets containing different amounts of saturated or unsaturated fat throughout life. These diets produced characteristic changes in cardiac phospholipid fatty acid composition, but produced no significant differences in fatty acid composition of phospholipids from a crude membrane fraction of brain. When littermates of these animals were exposed to ethanol vapour in an inhalation chamber it was observed that mice which had received a diet high in saturated fat lost the righting reflex at an estimated concentration of ethanol in blood higher than that required for mice receiving a control diet, or a diet rich in polyunsaturated fat. Analysis of the brain membrane fraction from those animals which had received ethanol revealed that mice receiving the highly saturated fat diet now had a significantly greater proportion of saturated fatty acids in brain membrane phospholipids. These results are discussed in relation to the hypothesis that brain membrane lipid composition may influence the behavioural response to ethanol. 相似文献
49.
Phylogenetic relationships among prokaryotic and eukaryotic catalases 总被引:13,自引:1,他引:12
Seventy-four catalase protein sequences, including 29 bacterial, 8 fungal,
7 animal, and 30 plant sequences, were compiled, and 70 were used for
phylogenetic reconstruction. The core of the resulting tree revealed
unique, separate groups of plant and animal catalases, two groups of fungal
catalases, and three groups of bacterial catalases. The only overlap of
kingdoms occurred within one branch and involved fungal and bacterial
large-subunit enzymes. The other fungal branch was closely linked to the
group of animal enzymes. Group I bacterial catalases were more closely
related to the plant enzymes and contained such diverse taxa as the
Gram-positive Listeria seeligeri, Deinocococcus radiodurans, and
gamma-proteobacteria. Group III bacterial sequences were more closely
related to fungal and animal sequences and included enzymes from a broad
range of bacteria including high- and low-GC Gram positives,
proteobacteria, and a bacteroides species. Group II was composed of
large-subunit catalases from diverse sources including Gram positives
(low-GC Bacilli and high-GC Mycobacteria), proteobacteria, and species of
the filamentous fungus Aspergillus. These data can be interpreted in terms
of two gene duplication events that produced a minimum of three catalase
gene family members that subsequently evolved in response to environmental
demands. Horizontal gene transfer may have been responsible for the group
II mixture of bacterial and fungal large-subunit catalases.
相似文献
50.
Dipeptidyl peptidase IV (DPP-IV/CD26) is a multifunctional type II transmembrane serine peptidase. This enzyme contributes to the regulation of various physiological processes, including blood sugar homeostasis, by cleaving peptide hormones, chemokines and neuropeptides. We have determined the 2.5 A structure of the extracellular region of DPP-IV in complex with the inhibitor valine-pyrrolidide. The catalytic site is located in a large cavity formed between the alpha/beta-hydrolase domain and an eight-bladed beta-propeller domain. Both domains participate in inhibitor binding. The structure indicates how substrate specificity is achieved and reveals a new and unexpected opening to the active site. 相似文献