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31.
K. T. Castle B. A. Wunder 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1995,164(8):609-617
We fed prairie voles (Microtus ochrogaster) rat chow diluted with variable amounts of -cellulose to determine 1) how much fiber the voles could tolerate in their diet; 2) changes in food intake and digestibility of dry matter and of fiber; 3) the extent to which voles utilized fiber as an energy source; and 4) whether any of these variables differed between groups of animals maintained at 5 or 22°C. Fiber content of the diets ranged from 20 to 84%. Animals held at 5°C maintained body mass through a diet containing 69% fiber, while animals held at 22°C maintained body mass through the 84% fiber diet. Dry matter intake increased with fiber level from 9.3 to 15.0 g·day-1 for animals at 5°C and from 5.6 to 14.0 g·day-1 for animals at 22°C; intake on the highest fiber diet eaten by either group was not different. Dry matter digestibility decreased significantly as the fiber in the diets increased, but was not affected by temperature treatments. Digestible dry matter intake for each group remained constant regardless of diet quality, but on each diet digestible dry matter intake for animals at 5°C was significantly higher than that of the animals held at 22°C. Digestibility of the fiber portion of the experimental diets remained constant as food quality decreased, so the percent of daily energy need met by fiber utilization increased with higher food intake. On the lowest quality diet each group tolerated, fiber digestion provided approximately 42 and 68% of the energy needs of voles at 5 and 22°C, respectively.Abbreviations BM
body mass
- BMR
basal metabolic rate
- DE
digestible energy
- DM
dry matter
- DMD
dry matter digestibility
- DDMI
digestible dry matter intake
- MR
metabolic rate
- NDF
neutral detergent fiber (=cell walls)
- NDS
neutral detergent solubles (=cell solubles)
- SEM
standard error of mean
-
T
a
ambient temperature 相似文献
32.
Assumpció Bosch Stefan Wiemann Jordi Guimerá Wilhelm Ansorge David Patterson Xavier Estivill 《Human genetics》1995,95(1):119-122
Five clones, containing polymorphic CA-repeat sequences, have been isolated from a specific human chromosome 21 phage library and have been localised to band q21 of chromosome 21 using a somatic cell hybrid panel. These highly repetitive sequences (D21S1263, D21S1264, D21S1415, D21S1417 and D21S1420) have been characterised in the CEPH reference parents and have heterozygosities ranging from 0.30 to 0.81 and an average polymorphism information content (PIC) of 0.62. The relative order of these markers, based on the somatic cell hybrid panel, is cen-D21S1417, D21S1420-D21S1263, D21S1415-D21S1264-tel. The most polymorphic marker (D21S1264) has been included in the chromosome 21 genetic map. They have also been localised in the CEPH/ Généthon YAC panel, providing a refined localisation of these polymorphic sequences. These five CA-repeat markers should provide a better characterisation of the q21 region of chromosome 21. 相似文献
33.
Selective cloning of Bacillus subtilis xylose isomerase and xylulokinase in Escherichia coli genes by IS5-mediated expression. 总被引:11,自引:0,他引:11 下载免费PDF全文
A fragment of Bacillus subtilis DNA coding for xylose isomerase and xylulokinase was isolated from a BamHI restriction pool by complementation of an isomerase-defective Escherichia coli strain. The spontaneous insertion of IS5, which occurred during the very slow growth of the E. coli xyl- cells on xylose, allowed the expression of the cloned Bacillus genes in E. coli. Without IS5 insertion, the xylose genes were inactive in E. coli. Deletion experiments indicated that the control of the expression resides within a 270-bp long region at the right end of IS5. Deletion of this region led to a loss of expression, which could be restored by insertion of the lacUV5 promoter fragment at the deletion site. Sequence analysis showed that the site of IS5 insertion is 195 bp upstream from the putative ATG initiation codon of the xylose isomerase structural gene. This ATG is preceded by a ribosome binding sequence and two hexamers also found in promoter regions of other Bacillus genes. Deletion and mutagenesis analysis led to a preliminary map of the Bacillus xylose operon. 相似文献
34.
Edvin Wilhelm Johannesen 《Nordic Journal of Botany》1984,4(4):513-520
Forty–nine species of myxomycetes are reported as new to Norway. Of these, 22 species are new to Scandinavia. Several have not, or only rarely, been reported from Europe. Two species (viz. Diderma subfloriformis and Comatricha anomala) were previously known only from their type localities. Brief discussions are given for some of the more interesting species. 相似文献
35.
The binding of the natural and unnatural diastereoisomers 25-hydroxyvitamin D3-26,23-lactone and 1,25 dihydroxyvitamin D3-26,23-lactone to the vitamin D-binding protein (DBP) and 1,25 dihydroxyvitamin D3 [1,25(OH)2D3] chick intestinal receptor have been investigated. Also, the biological activities, under in vivo conditions, of these compounds, in terms of intestinal calcium absorption (ICA) and bone calcium mobilization (BCM), in the chick are reported. The presence of the lactone ring in the C23-C26 position of the seco-steroid side chain increased two to three times the ability of both 25(OH)D3 and 1,25(OH)2D3 to displace 25(OH)[3H]D3 from the D-binding protein; however, the DBP could not distinguish between the various diastereoisomers. In contrast, the unnatural form (23R,25S) of the 25-hydroxy-lactone was found to be 10-fold more potent than the natural form, and the unnatural (23R,25S)1,25(OH)2D3-26,23-lactone three times more potent than the natural 1,25-dihydroxy-lactone in displacing 1,25(OH)2[3H]D3 from its intestinal receptor. While studying the biological activity of these lactone compounds, it was found that the natural form of the 25-hydroxy-lactone increased the intestinal calcium absorption 48 h after injection (16.25 nmol), while bone calcium mobilization was decreased by the same dose of the 25-hydroxy-lactone. The 1,25-dihydroxyvitamin D3-26,23-lactone in both its natural and unnatural forms was found to be active in stimulating ICA and BCM. These results suggest that the 25-hydroxy-lactone has some biological activity in the chick and that 1,25(OH)2D3-26,23-lactone can mediate ICA and BCM biological responses, probably through an interaction with 1,25-(OH)2D3 specific receptors in these target tissues. 相似文献
36.
37.
Paul Kuppert Siegrun Wilhelm Klaus-Dieter Spindler 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1978,128(2):95-100
Summary From in vitro experiments using different binding assays it is in crayfish demonstrated that the cytosol of target tissues is able to bind both ecdysone and ecdysterone. The ability to bind ecdysteroids is destroyed by heating and by treatment with -chymotrypsin and N-ethyl-maleinimide (NEM) (Figs. 4, 5). In target tissues there is a strong positive correlation between protein content and binding (Fig. 6). The association of the hormone-protein-complex is rapid, taking only a few min even at 5° C (Fig. 3). The binding of the two hormones to the cytosol is both specific and saturable. The association constants for the cytoplasmic receptors from hypodermis, hindgut and midgut gland are in the range of 3–6×107 M–1 for ecdysone and 5–7×108 M–1 for ecdysterone (Fig. 8). The data suggest the existence of cytoplasmic ecdysteroid receptors. 相似文献
38.
39.
40.
Epidermal and seed surface characters of plants: systematic applicability and some evolutionary aspects 总被引:1,自引:0,他引:1
Wilhelm Barthlott 《Nordic Journal of Botany》1981,1(3):345-355
Based on SEM examinations of about 5000 species of seed plants, this is a survey of their epidermal surface characters with an aim to application in taxonomy. Surface characters may be grouped into four categories: (1) Cellular arrangement or cellular pattern. (2) Shape of cells (the "primary sculpture" of a surface). (3) Relief of outer cell walls (the "secondary sculpture" superimposed on the primary sculpture), caused mainly by cuticular striations and superficially visible wall inclusions and wall thickenings. (4) Epicuticular secretions (the "tertiary sculpture" superimposed on the secondary sculpture), i.e. mainly waxes and related substances.
The systematic applicability is discussed for each of these structural groups. Epidermal characters are only slightly influenced by environmental conditions. Their high structural diversity provides most valuable criteria for the classification between species and family level. There is also some evidence for their systematic applicability above the family level.
The possible evolutionary–ecological significance of surface sculpturing is discussed briefly. There is evidence that these features may be seen primarily under the aspects of reduced ability of plants to contaminate and as temperature control mechanisms of the surfaces. 相似文献
The systematic applicability is discussed for each of these structural groups. Epidermal characters are only slightly influenced by environmental conditions. Their high structural diversity provides most valuable criteria for the classification between species and family level. There is also some evidence for their systematic applicability above the family level.
The possible evolutionary–ecological significance of surface sculpturing is discussed briefly. There is evidence that these features may be seen primarily under the aspects of reduced ability of plants to contaminate and as temperature control mechanisms of the surfaces. 相似文献