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991.
992.
The taste of polycose in hamsters 总被引:2,自引:2,他引:0
Hamsters show a preference for Polycose, a mixture of starch-derived
glucose polymers, that is as strong as their preference for sucrose.
However, in the hamster, taste aversions to Polycose may be less easily
acquired than taste aversions to sucrose and the qualitative aspects of
Polycose are unknown in this species. In order to examine the taste of
Polycose in the hamster, we utilized a taste-aversion protocol with two
conditioning trials. Animals were trained to avoid one of three different
conditioning stimuli: 50 mM sucrose, 100 mM Polycose and a mixture of 50 mM
sucrose with 100 mM Polycose. Control animals were conditioned with
deionized water. After the second conditioning trial, generalization
testing began for the three conditioning stimuli plus 3 mM citric acid, 300
mM KCI and 30 mM NaCl. The results showed that aversions to Polycose,
sucrose or the Polycose/sucrose mixture cross- generalized, demonstrating
that Polycose and sucrose share a common taste percept in the hamster. None
of the aversions generalized to NaCl, citric acid or KCI. In addition,
comparisons among the patterns of taste generalizations indicated that the
tastes of Polycose and sucrose also had distinct qualitative components.
Finally, although the taste of 100 mM Polycose was more salient than the
taste of 50 mM sucrose, the taste of sucrose could still be detected in a
mixture with Polycose.
相似文献
993.
The 67-kDa laminin receptor originated from a ribosomal protein that acquired a dual function during evolution 总被引:8,自引:0,他引:8
Ardini E; Pesole G; Tagliabue E; Magnifico A; Castronovo V; Sobel ME; Colnaghi MI; Menard S 《Molecular biology and evolution》1998,15(8):1017-1025
The 67-kDa laminin receptor (67LR) is a nonintegrin cell surface receptor
that mediates high-affinity interactions between cells and laminin.
Overexpression of this protein in tumor cells has been related to tumor
invasion and metastasis. Thus far, only a full-length gene encoding a
37-kDa precursor protein (37LRP) has been isolated. The finding that the
cDNA for the 37LRP is virtually identical to a cDNA encoding the ribosomal
protein p40 has suggested that 37LRP is actually a component of the
translational machinery, with no laminin-binding activity. On the other
hand, a peptide of 20 amino acids deduced from the sequence of 37LR/p40 was
shown to exhibit high laminin-binding activity. The evolutionary
relationship between 23 sequences of 37LRP/p40 proteins was analyzed. This
phylogenetic analysis indicated that all of the protein sequences derive
from orthologous genes and that the 37LRP is indeed a ribosomal protein
that acquired the novel function of laminin receptor during evolution. The
evolutionary analysis of the sequence identified as the laminin-binding
site in the human protein suggested that the acquisition of the
laminin-binding capability is linked to the palindromic sequence LMWWML,
which appeared during evolution concomitantly with laminin.
相似文献
994.
Olga Gorbounova Anne-Lie Svensson Patrik Jönsson Malahat Mousavi Hui Miao Eva Hellström-Lindahl Agneta Nordberg 《Journal of neurochemistry》1998,70(3):1134-1142
Abstract: For a study of the underlying mechanisms of a possible interaction between ethanol and nicotinic receptors during ethanol dependence, the aim of this work was to investigate the effect of chronic ethanol exposure on nicotinic receptor subtypes in a transfected fibroblast cell line (M10 cells) stably expressing α4β2 nicotinic receptor subtype and an SH-SY5Y neuroblastoma cell line expressing α3, α5, α7, β2, and β4 nicotinic acetylcholine receptor (nAChR) subunits. A significant dose-related decrease (−30–80%) in number of [3 H]nicotine binding sites was observed in ethanol-treated (25–240 m M ) compared with untreated M10 cells. Similarly, 4-day treatment with ethanol in concentrations relevant to chronic alcoholism (100 m M ) decreased the number of nicotinic receptor binding sites in the SH-SY5Y cells when measured using [3 H]epibatidine. When M10 cells were chronically treated with nicotine, ethanol partly inhibited the up-regulation of nicotinic receptors when present in the cells together with nicotine. Chronic treatment for 4 days with 100 m M ethanol significantly decreased the mRNA level for the α3 nAChR subunit (−39%), while the mRNA levels for the α7 (+30%) and α4 (+22%) subunits were significantly increased. Chronic ethanol treatment did not affect the mRNA levels for the β2 nAChR subunit. Changes in the levels of nAChR protein and mRNA may have adaptive significance and be involved in the development of dependence, tolerance, and addiction to chronic ethanol and nicotine exposure. They also may be targets for therapeutic strategies in the treatment of ethanol and nicotine dependence. 相似文献
995.
We investigated the lifetime mating potential and the reproductive behavior of male and female turnip moths Agrotis segetum (Schiff.) under field and laboratory conditions. The sex ratio was 1 : 1 in a lab-reared population as well as in two wild populations. Males were capable of mating repetitively a relatively large number of times (mean of 6.7 ± 2.7 matings) when given access to new virgin females throughout their lifetimes. Females seldom mated more than once (mean ± 1.3 ± 0.6 matings), indicating a male-biased operational sex ratio. The mean potential lifetime mating was five times higher in males, while the coefficient of variance was lower in males. There was no differences in longevity between animals that were allowed to mate and animals not allowed to mate, indicating no direct costs or benefits of mating in physiological terms. In males, the number of matings was positively correlated with longevity, but this was not the case in females. Nor was there a correlation between the number of female matings and the number of fertilized eggs. There was a negative correlation between the number of eggs fertilized and the number of times males had previously mated, indicating that male ejaculates were limited. Male spermatophore size also decreased with number of achieved matings. Laboratory-reared females attracted males in the field throughout their lifetimes, with a peak at 3–7 days of age. Wild males, allowed to choose between pairs of caged females in the field, were attracted in equal numbers to females of different ages. Females did not show any mate-rejection behavior in the field. They mated with the first male that courted them. No incidence of mate replacement by males arriving later to already courted females were recorded. 相似文献
996.
997.
Anaerobic degradation of phthalic acid esters during digestion of municipal solid waste under landfilling conditions 总被引:6,自引:0,他引:6
Anaerobic microorganisms in municipal solid waste samples from laboratory-scale landfill reactors and a pilot-plant biogas digestor were investigated with the aim of assessing their ability to transform four commercially used phthalic acid esters (PAEs) and phthalic acid (PA). The PAEs studied were diethyl phthalate (DEP), butylbenzyl phthalate (BBP), dibutyl phthalate (DBP) and bis(2-ethylhexyl) phthalate (DEHP). No biological transformation of DEHP could be detected in any of the experiments. Together with waste samples from the simulated landfilling conditions, the PAEs (except DEHP) were hydrolytically transformed to their corresponding monoesters. These accumulated as end products, and in most cases they were not further degraded. During incubation with waste from the biogas digestor, the PAEs (except DEHP) were completely degraded to methane and carbon dioxide. The influence of the landfill development phase on the transformations was investigated utilizing PA and DEP as model substances. We found that during both the intense and stable methanogenic (but not the acidogenic) phases, the microoganisms in the samples had the potential to transform PA. A shorter lag phase was observed for the PA transformation in the samples from the stable methanogenic phase as compared with earlier phases. This indicates an increased capacity to degrade PA during the aging phases of the municipal solid waste in landfills. No enhancement of the DEP transformation could be observed as conditions in the methanogenic landfill model changed over a year's time. The results indicate that microorganisms developing in a methanogenic landfill environment have a substantially lower potential to degrade PAEs compared with those developing in a biogas reactor.Abbreviations BBP
butylbenzyl phthalate
- DEHP
bis(2-ethylhexyl) phthalate
- CoA
coenzyme A
- DBP
dibutyl phthalate
- DEP
diethyl phthalate
- DS
dry solids
- MBeP
monobenzyl phthalate
- MBuP
monobutyl phthalate
- MEP
monoethyl phthalate
- MSW
municipal solid waste
- PA
phthalic acid
- PAE(s)
phthalic acid ester(s)
- VFA
volatile fatty acids 相似文献
998.
Tokics Leif; Hedenstierna Goran; Svensson Leif; Brismar Bo; Cederlund Torsten; Lundquist Hans; Strandberg Ake 《Journal of applied physiology》1996,81(4):1822-1833
Tokics, Leif, Göran Hedenstierna, Leif Svensson, BoBrismar, Torsten Cederlund, Hans Lundquist, and ÅkeStrandberg. / distributionand correlation to atelectasis in anesthetized paralyzed humans.J. Appl. Physiol. 81(4):1822-1833, 1996.Regional ventilation and perfusion were studiedin 10 anesthetized paralyzed supine patients by single-photon emissioncomputerized tomography. Atelectasis was estimated from twotransaxial computerized tomography scans. The ventilation-perfusion(/) distribution was alsoevaluated by multiple inert gas elimination. While the patients wereawake, inert gas / ratio wasnormal, and shunt did not exceed 1% in any patient. Computerizedtomography showed no atelectasis. During anesthesia, shunt ranged from0.4 to 12.2%. Nine patients displayed atelectasis (0.6-7.2% ofthe intrathoracic area), and shunt correlated with the atelectasis(r = 0.91, P < 0.001). Shunt was located independent lung regions corresponding to the atelectatic area. There wasconsiderable / mismatch, withventilation mainly of ventral lung regions and perfusion of dorsalregions. Little perfusion was seen in the most ventral parts (zone 1)of caudal (diaphragmatic) lung regions. In summary, shunt during anesthesia is due to atelectasis in dependent lung regions. The / distributions differ fromthose shown earlier in awake subjects. 相似文献
999.
Attraction of maleAgrotis segetum Dennis & Schiffermüller (Lepidoptera: Noctuidae) to sex pheromone traps in fields, which were treated with one or three pheromone
components was investigated. Small plots of 1/4ha size were treated with synthetic pheromone, released by 25 evenly dispersed
latex rubber tube dispensers. The dispensers were loaded with either 500 μg Z5-10:OAc (50 mg/ha), or 1000 μg Z7-12:OAc (100
mg/ha), or a 3-component mixture consisting of 500 μg Z5-10:OAc+1000 μg Z7-12:OAc+1000 μg Z9-14:OAc. Pheromone traps were
placed both within and outside of the treated area in a cross design, with an intertrap spacing of 15 m. Release rates from
disruption dispensers were measured in the laboratory after being exposed in the field. The release rates of the components
were estimated to be 0.44, 0.11, and 0.06 μg/h/dispenser for Z5-10:OAc, Z7-12:OAc and Z9-14:OAc, respectively. The highest
effect of disruption was achieved by the three-component blend, resulting in a significant suppression of trap catches extending
5 m outside of the treated area. The Z5-10:OAc treatment resulted in reduced trap catches inside the treated area, but the
effect did not extend outside. Z7-12:OAc alone did not result in any significant reduction in trap catch. The results indicate
that different mechanisms may explain the disruptive effect of the treatments and that the single pheromone components are
not as effective as the three-component blend. 相似文献
1000.
Recurrence of the R408W Mutation in the Phenylalanine Hydroxylase Locus in Europeans 总被引:8,自引:3,他引:5
Randy C. Eisensmith Alexei A. Goltsov Charles O'Neill Linda A. Tyfield Eugene I. Schwartz Alexei I. Kuzmin Svetlana S. Baranovskaya Gennady L. Tsukerman Eileen Treacy Charles R. Scriver Flemming Güttler Per Guldberg Hans G. Eiken Jaran Apold Elisabeth Svensson Eileen Naughten Seamus F. Cahalane David T. Croke Forrester Cockburn Savio L. C. Woo 《American journal of human genetics》1995,56(1):278-286
The relative frequency of the common phenylalanine hydroxylase (PAH) mutation R408W and its associations with polymorphic RFLP, VNTR, and short-tandem-repeat (STR) sites in the PAH gene were examined in many European populations and one representative North American population of defined European descent. This mutation was found to cluster in two regions: in northwest Europe among Irish and Scottish peoples, and in eastern Europe, including the Commonwealth of Independent States. This allele was significantly less frequent in intervening populations. In eastern European populations, the R408W mutation is strongly associated with RFLP haplotype 2, the three-copy VNTR allele (VNTR 3), and the 240-bp STR allele. In northwestern European populations, it is strongly associated with RFLP haplotype 1, the VNTR allele containing eight repeats (VNTR 8), and the 244-bp STR allele. An examination of the linkage between the R408W mutation and highly polymorphic RFLP, VNTR, and STR haplotypes suggests that recurrence is the most likely mechanism to account for the two different major haplotype associations of R408W in Europe. 相似文献