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101.
Fatty-acid synthesis has been measured in vivo with3H2O in cafeteria-fed rats exhibiting diet-induced thermogenesis. Synthesis was decreased in brown adipose tissue, the liver, white adipose tissue, and the carcass of the cafeteria-fed animals compared to rats fed the normal stock diet. Whole-body synthesis was also decreased in the cafeteria-fed group. Diet-induced thermogenesis, in contrast to cold-induced non-shivering thermogenesis does not lead to increased fatty-acid synthesis and this is presumably due to the inhibitory effects on lipogenesis of the high dietary fat intake characteristic of cafeteria diets. The results also indicate that the energy cost of body fat deposition in cafeteria-fed rats is lower than in animals fed a low-fat/high-carbohydrate stock diet. 相似文献
102.
Nirmala SundarRaj Judith Martin Nancy Hrinya 《Biochemical and biophysical research communications》1982,106(1):48-57
Hybridomas which secrete monoclonal antibodies against human type III procollagen have been developed. By an enzyme-linked immunosorbent assay, three of the monoclonal antibodies have been determined to be against non-helical extensions of the molecules while two of the antibodies are against helical portion of the molecules which is sensitive to bacterial collagenase action. These findings have been further confirmed by carrying out immuno-reaction of the pro α-chains transferred on nitrocellulose paper from sodium dodecyl sulfate polyacrylamide gels. These monoclonal antibodies have been found to be suitable reagents for immunohistochemical studies as well as for immunoassays of type III procollagen and collagen. 相似文献
103.
Nancy B. Wurster George Lust 《Biochemical and biophysical research communications》1982,109(4):1094-1101
A large non-collagenous protein was extracted from degenerated cartilage of osteoarthritic canine joints. Evidence was presented that this protein is fibronectin. It had a molecular weight identical to that of fibronectin isolated from canine serum, required the presence of heparin and urea in the extraction buffer for solubilization, reacted with both polyclonal and monoclonal antibodies to fibronectin in an enzyme-linked immunosorbent assay (ELISA), and exhibited gelatin binding properties. Fibronectin was detected in normal cartilage as well, although in lesser amounts than observed in osteoarthritic cartilage. 相似文献
104.
Nancy Auestad Rose A. Korsak Jack W. Morrow John Edmond 《Journal of neurochemistry》1991,56(4):1376-1386
The oxidation of the fatty acids octanoate and palmitate to CO2 and the ketone bodies acetoacetate and D-(-)-3-hydroxybutyrate was examined in astrocytes that were prepared from cortex of 2-day-old rat brain and grown in primary culture to confluence. Accumulation of acetoacetate (by mass) in the culture medium of astrocytes incubated with octanoate (0.3-0.5 mM) was 50-90 nmol C2 units h-1 mg of protein-1. A similar rate was obtained using radiolabeled tracer methodology with [1-14C]octanoate as labeled substrate. The results from the radiolabeled tracer studies using [1-14C]- and [7-14C]octanoate and [1-14C]-, [13-14C]-, and [15-14C]palmitate indicated that a substantial proportion of the omega-terminal four-carbon unit of these fatty acids bypassed the beta-ketothiolase step of the beta-oxidation pathway and the 3-hydroxy-3-methylglutaryl (HMG)-CoA cycle of the classic ketogenic pathway. The [14C]acetoacetate formed from the 1-14C-labeled fatty acids, obligated to pass through the acetyl-CoA pool, contained 50% of the label at carbon 3 and 50% at carbon 1. By contrast, the [14C]acetoacetate formed from (omega-1)-labeled fatty acids contained 90% of the label at carbon 3 and 10% at carbon 1, whereas that formed from the (omega-3)-labeled fatty acid contained 20% of the label at carbon 3 and 80% at carbon 1. These results indicate that acetoacetate is primarily formed either by the action of 3-oxo-acid-CoA transferase (EC 2.8.3.5) or acetoacetyl-CoA deacylase (EC 3.1.2.11) or both on acetoacetyl-CoA and not by the action of the mitochondrial HMG-CoA cycle involving HMG-CoA lyase (EC 4.1.3.4), which was readily detected, and HMG-CoA synthase (EC 4.1.3.5), which was barely measurable. 相似文献
105.
Optical melting curves of seven DNA dumbbells with the 16 base-pair duplex sequence 5'G-C-A-T-A-G-A-T-G-A-G-A-A-T-G-C3' linked on both ends by Tn (n = 2, 3, 4, 6, 8, 10, and 14) loops measured in 30, 70, and 120 mM Na+ are analyzed in terms of the numerically exact statistical thermodynamic model of DNA melting. The construction and characterization of these molecules were described in the previous paper (Amaratunga et al., 1992). As was recently reported for hairpins (T. M. Paner, M. Amaratunga, M. J. Doktycz, and A. S. Benight, 1990, Biopolymers, Vol. 29, pp. 1715-1734) theoretically calculated melting curves were fitted to experimental curves by simultaneously adjusting the parameters representing loop and circle formation to optimize the fits. The systematically determined empirical parameters provide evaluations of the free energies of hairpin loop formation delta Gloop (n) and single-strand circles delta Gcircle (N), as a function of end loop size, n = 2-14, and circle size, N = 32 + 2n. The dependence of these quantities on solvent ionic strength over the range from 30 to 120 mM Na+ was evaluated. An approximately analytical expression for the partition function Q(T) of the dumbbells was formulated that allowed a means for determining the transition enthalpy delta H degrees and entropy delta S degrees for every dumbbell, revealing the dependence of these quantities on loop size. In this multistate approach a manifold of partially melted intermediate microstates are considered and therefore no assumptions regarding the nature of the melting transitions (that they are two-state) are required. The transition thermodynamic parameters were also determined from a van't Hoff analysis of the melting curves. Comparisons between the results of the multistate analysis and the two-state van't Hoff analysis revealed significant differences for the dumbbells with larger end loops, indicating that the melting transitions of the larger looped dumbbells deviate considerably from two-state behavior. Results are then compared with published melting studies of much larger DNA dumbbells (D. B. Naritsin and Y. L. Lyubchenko, 1990, Journal of Biomolecular Structure and Dynamics, Vol. 8, pp. 1-13), of small hairpins (Paner et al., 1990; M. J. Doktycz, T. M. Paner, M. Amaratunga and A. S. Benight, 1990, Biopolymers, Vol. 30, pp. 829-845) and another dumbbell (A. S. Benight, J. M. Schurr, P. F. Flynn, B. R. Reid, and D. E. Wemmer, 1988) Journal of Molecular Biology, Vol. 200, pp. 377-399).(ABSTRACT TRUNCATED AT 400 WORDS) 相似文献
106.
Summary To examine the effects of predators and plant genotype on the behavior, patterns of herbivory, growth and survivorship of caterpillars, we used an experimental garden in which we contrasted two hostplant genotypes of plantain (Plantago lanceolata), two kinds of herbivores (specialist Junonia coenia vs. generalist Pyrrharctia isabella) and two levels of caterpillar predation (with and without Podisus maculiventris stinkbugs). Each of the replicate plots per treatment contained two plants of the same genotype. The stinkbugs reduced the survivorship of the specialist caterpillars but not that of the generalists, which reflects the differences in predatoravoidance behaviors of these species. Nonetheless, the stinkbugs influenced the behavior of both caterpillar species. When stinkbugs were present, both specialist and generalist caterpillars were less likely to be found on the plant upon which they were initially placed (=initial plant), and they were more likely to be off both plants within the plot than larvae in the absence of predators. Consequently in the presence of the stinkbug predators, the proportion of the initial plants consumed was less than in the absence of the predators. Plant genotype influenced plant size and the proportion of individual plants eaten, but it did not affect larval location on the plots. Neither presence of predators nor plant genotype had an effect on relative growth rate of the caterpillars. 相似文献
107.
Biogeographic comparisons of marine algal polyphenolics: evidence against a latitudinal trend 总被引:5,自引:1,他引:4
Nancy M. Targett Loren D. Coen Anne A. Boettcher Christopher E. Tanner 《Oecologia》1992,89(4):464-470
Summary Marine allelochemicals generally are present in greater quantity and diversity in tropical than in temperate regions. Marine algal polyphenolics have been reported as an apparent exception to this biogeographic trend, with literature values for phenolic concentrations significantly higher in temperate than in tropical brown algae. In contrast, our results, the first reported for Caribbean brown algae (orders Dictyotales and Fucales), show that many species have high phenolic levels. In addition, both our study and previous studies with north temperate and tropical species demonstrate that there is marked variation in algal phenolic levels within species from different locations. We conclude that high phenolic concentrations occur in species from both temperate and tropical regions, indicating that latitude alone is not a reasonable predictor of plant phenolic concentrations. 相似文献
108.
Use of a Plasmid DNA Probe To Monitor Populations of Bacillus pumilus Inoculant Strains in Hay 总被引:2,自引:0,他引:2 下载免费PDF全文
Carol A. Hendrick Brenda K. Smiley Terrence H. Shelley Nancy J. Tomes 《Applied microbiology》1991,57(3):686-693
We are evaluating naturally occurring isolates of Bacillus pumilus for use as microbial hay preservatives. Seven isolates of B. pumilus from hay contained a 42-kb cryptic plasmid (pMGD296). We wished to determine whether pMGD296 could be used as a molecular marker to follow populations of these isolates in hay over time. Southern blots and colony blots of 69 isolates of B. pumilus and other Bacillus spp. were probed with 32P-labeled pMGD296. Twenty-nine probe-positive isolates were identified; of these, 28 contained a plasmid with a restriction profile identical to that of pMGD296. One isolate from untreated hay contained a 40-kb plasmid (pMGD150) that was homologous to pMGD296 but had a different restriction fragment pattern. Regions of homology between the two plasmids were identified by Southern blotting, and a 1.9-kb HindIII-PstI fragment of pMGD296 lacking strong homology to pMGD150 was cloned in pUC18. The cloned fragment hybridized only with isolates containing pMGD296 and was used to estimate populations of these isolates in treated and untreated hay. 相似文献
109.
Nancy Lynn Rosenberg-Nicolson 《Journal of cellular biochemistry》1991,47(1):11-17
Nucleosome cores were digested with α-chymotrypsin until histone H3 was degraded to a partial histone, CP1. As we reported previously, cleavage occurred at leucine 20 to H3 and resulted in an increase in circular dichroism between 265 to 285 nm. Some modest core unfolding was also observed as determined by a small decrease in the sedimentation coefficient. Studies reported here deal with the analysis of core secondary structure and subsequent perturbation caused by treatment with α-chymotrypsin. Raman spectroscopy indicated that chymotryptic treatment promoted a change in the conformational environment of a population of core histone tyrosines. In addition, a shift from B-form to an intermediate B- or A-form was observed for core DNA. High-resolution thermal denaturation was used to determine alterations in the stabilization of core DNA related to perturbation of the core histones. Brief chymotryptic treatment indicated changes in both pre-melt and irreversible transitions. 相似文献
110.
Summary During late spring, 1987, observations were made of nitrate and ammonium uptake in two regions of the Greenland Sea, the Arctic Front and the Polar Front. In the area of the Arctic Front, mixed layers were relatively deep (generally below 100m), and the 1% isolume averaged 35 m. Ambient nitrate concentrations were always greater than 6 M, whereas ammonium levels were always less than 0.6 M. Surface nitrate and ammonium specific uptake rates averages 4.4 and 2.3×10–3 h–1, respectively. The Polar Front generally coincided spatially with the location of the ice edge, and vertical mixed layers were shallow (pycnocline depth ranged from 8–14 m), and the 1 % isolume averaged 37 m. Nitrate concentrations were somewhat lower than in the Arctic Front, but remained above 3 M at all times. Ammonium levels reached 1.2 M. Nitrate and ammonium specific uptake rates at the surface averaged 4.8×10–3 and 10×10–3 h–1, respectively. Integrated water column f-ratios for the Arctic and Polar Front regions averaged 0.63 and 0.31, and the ammonium relative preference indices at all depths within each study area were always greater than 8, indicating that ammonium remained the preferred nitrogen source for phytoplankton. New production in the two regions was approximately equal, but the Polar Front had a substantially greater amount of regenerated production, and hence total production as well. Irradiance (and not nutrient concentration) seems to be the most important environmental factor in controlling nitrogen uptake. The spatial variability observed within the Greenland Sea suggest that inclusion of this region in global carbon models will require increased spatial resolution of both the models and the data included. 相似文献