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41.
Summary Isolated nerve cells fromLymnaea stagnalis were studied using the internal-perfusion and patch-clamp techniques. Patch excision frequently activated a voltage-independent Ba2+-permeable channel with a slope conductance of 27 pS at negative potentials (50mm Ba2+). This channel is not seen in patches on healthy cells and, unlike the voltage-dependent Ca channel, is not labile in isolated patches. The activity of the channel in inside-out patches is unaffected by intracellular ATP, Ca2+ below 1mm or the catalytic subunit of cAMP-dependent protein kinase but is reversibly blocked by millimolar intracellular Ca2+ or Ba2+. The channel can be activated in on-cell patches by either internal perfusion with high Ca2+ or the long-term internal perfusion of low Ca2+ solutions not containing ATP. These channels may carry the inward Ca2+ current which causes a regenerative increase in intracellular Ca+ when snail neurons are perfused with high Ca2+ solutions. High internal Ca2+, or long periods of internal perfusion with ATP-free solutions, induces an increase in a resting (–50 mV) whole-cell Ba2+ conductance. This conductance can be turned off by returning the intracellular perfusate to a low Ca2+ solution containing ATP and Mg2+. The activity of this channel appears to have an opposite dependence on intracellular conditions to that of the voltage-dependent Ca channel. 相似文献
42.
Grain sorghum can substitute for corn as a full season crop and replace soybeans in double cropping systems with wheat in the southeastern United States. Relatively few studies have been conducted to measure the response of grain sorghum to tillage, weed control method, and row spacing. These experiments were designed to determine the effects of weed control method and row spacing on no-till planted grain sorghum (Sorghum bicolor L. Moench G1516-BR) after wheat (Triticum aestivum L. Coker 68–15) and crimson clover (Trifolium incarnatum L. Bigbee) grown for winter forage in comparison to sorghum planted on a conventionally prepared seedbed. The experiment included 45, 60, and 90 cm row spacings and three weed control regimes: none, mechanical, and chemical. Grain sorghum planted no-till in crimson clover or wheat sod yielded considerably more grain than conventionally planted sorghum. Grain sorghum produced significantly higher yields in 45-cm rows than in 60-and 90-cm row spacings with all three planting methods. Effects of chemical weed control on weed population with all tillage methods and on grain yield with conventional tillage were significant. There were no significant differences in grain protein content due to row spacing or weed control method. 相似文献
43.
The major developments in the field of nuclear activation analysis, from 1936 to 1989, are discussed. The developments are
grouped into five consecutive time periods. The impact of various scientists on the development of the field in the first
35 years is also discussed. 相似文献
44.
Ryousuke Takahashi Katsumi Kawamura Jianguo Hu †Michiyuki Hayashi Takeo Deguchi 《Journal of neurochemistry》1996,67(2):525-529
Abstract: To study the level of ciliary neurotrophic factor (CNTF) in human nervous tissues, we developed a sensitive enzyme-linked immunoassay using a specific antibody against human CNTF. This method allowed us to detect as little as 0.3 ng/ml of human CNTF with good linearity and accuracy. Using this method, CNTF levels were determined in human sciatic nerves obtained at autopsy from 21 amyotrophic lateral sclerosis (ALS) patients and 48 subjects who had died of other neurological diseases. CNTF genotypes were also determined. The results indicated that CNTF levels were high in the normal homozygotes and approximately halved in the heterozygote subjects. There was, however, no significant difference in CNTF levels in the sciatic nerves between ALS and other neurological disease patients, indicating that the CNTF level was mainly determined by its genotypes and that the level in the sciatic nerves was not reduced in ALS patients. 相似文献
45.
Experiments were conducted in greenhouse, growth chamber, and laboratory conditions to determine the effect of ammonium sulfate [(NH4)2SO4] on the phytotoxicity, foliar uptake, and translocation of imazamethabenz on wild oat. Rates of (NH4)2SO4 up to 5% (w/v) applied with a greenhouse sprayer did not affect the phytotoxicity of the herbicide when the mix was applied at the one- to two-leaf stage. However, inclusion of 1 and 2% (NH4)2SO4 increased the phytotoxicity of the herbicide when the mix was sprayed at the two- to three-leaf, or the three- to four-leaf stage. At 10%, (NH4)2SO4 decreased the phytotoxicity of the sublethal dosage of the herbicide. When the herbicide was applied as individual drops to the growth chamber-grown plants, inclusion of (NH4)2SO4 at 1% did not affect phytotoxicity as measured by shoot growth. The presence of (NH4)2SO4 did not affect the amount of imazamethabenz retained by wild oat foliage, but it decreased [14C]imazamethabenz absorption, slightly antagonized acropetal translocation, and increased the basipetal translocation of [14C]imazamethabenz. It was concluded that application methods greatly modify the effect of (NH4)2SO4 on imazamethabenz phytotoxicity. Herbicide absorption and translocation as determined by one method do not necessarily represent the absorption and translocation patterns when different application methods are used. Absorption and translocation were not the factors that were responsible for the observed effect of (NH4)2SO4 on the herbicide phytotoxicity.Abbreviations SC
suspension concentrate 相似文献
46.
Yuzuru Hamada Toshifumi Udono Migaku Teramoto Tsutomu Sugawara 《Primates; journal of primatology》1996,37(3):279-295
Growth of chimpanzees reared at the Kumamoto Primates Park of Sanwa Kagaku Kenkyusho Co. Ltd. was studied cross-sectionally
from the viewpoints of somatic growth and reproductive maturation. Distance and velocity curves were expressed using spline
function method. Males showed adolescent growth acceleration in body weight, with a peak at 7.86 yrs of age, but not in trunk
length. Females showed continuous rapid growth from mid-juvenile to adolescent phase in both body weight and trunk length,
but no isolated adolescent spurt. The Sanwa chimpanzees matured at about 12.5 yrs of age for females and 15.0 yrs for males.
The mean adult weights and trunk lengths were 53.2 kg and 507.8 mm for males and 42.7 kg and 481.6 mm for females. The Sanwa
chimpanzees had similar growth patterns to those of the Yerkes chimpanzees, although they showed a slight delay in infancy,
and a higher growth rate from the early juvenile phase onwards. Growth patterns in these two laboratories may be regarded
as “normative” for laboratory-reared chimpanzees. They matured earlier than wild chimpanzees by more than two years. The major
reason for the retarded maturation in wild chimpanzees is the delay of growth from infant to the early juvenile phases (0–4
yrs of age), probably owing to a limited nutritional supply from the mother. Development of the testes comprised three phases:
slow growth from infant to juvenile (until 6.4 yrs); rapid growth around adolescence (until 9.2 yrs); and adult (mean testicular
volume, 187 cm3). Setting the nutritional standard at 2,000–2,600 Cal/day (= Kcal/day) per adult, calories were considered for captive chimpanzees
in each age class. 相似文献
47.
G. Thaller I. Hoeschele 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1996,93(7):1161-1166
A Bayesian approach to the statistical mapping of Quantitative Trait Loci (QTLs) using single markers was implemented via Markov Chain Monte Carlo (MCMC) algorithms for parameter estimation and hypothesis testing. Parameter estimators were marginal posterior means computed using a Gibbs sampler with data augmentation. Variables sampled included the augmented data (marker-QTL genotypes, polygenic effects), an indicator variable for linkage, and the parameters (allele frequency, QTL substitution effect, recombination rate, polygenic and residual variances). Several MCMC algorithms were derived for computing Bayesian tests of linkage, which consisted of the marginal posterior probability of linkage and the marginal likelihood of the QTL variance associated with the marker. 相似文献
48.
Estimation of the position and effect of a lethal factor locus on a molecular marker linkage map 总被引:3,自引:0,他引:3
R. Cheng A. Saito Y. Takano Y. Ukai 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1996,93(4):494-502
In the mapping of DNA markers the distortion of segregation of marker genotypes is often observed, which may be caused by a lethal factor acting in filial generations derived from distant crosses. A method is presented for estimating the recombination values between a lethal factor locus and neighboring molecular markers, and the relative viability or fertilization ability of gametes or zygotes affected by the lethal factor in an F2 population using the maximum likelihood method and the expectation conditional maximization (ECM) algorithm. Three selection models of gamete or zygote were considered, and the most likely one was determined by goodness of fit of the observed frequency of the phenotypes to the expected ones under the models. The method was applied to segregation data of molecular markers of an F2 population consisting of 144 individuals derived from a cross between an Indica and a Japonica rice variety. The presence of a lethal factor locus (L) located on chromosome III that caused partial gametic selection in both the male and female sides was suggested. The locus L was tightly linked to RFLP marker number 23 of the RFLP linkage map of Saito et al. (1991a), and the fertilization chance of a male or female gamete possessing the lethal factor was, on average, 41.5% of that of the normal gamete. 相似文献
49.
Peter T. Katzmarzyk William R. Leonard Merrill A. Stephen Peter R. Berti Allen G. P. Ross 《American journal of physical anthropology》1996,99(4):537-545
Estimates of daily energy expenditure are important for many areas of research in human ecology and adaptability. The most common technique for estimating human energy expenditure under field conditions, the factorial method, generally relies on activity-specific energy costs derived from published sources, based largely on North American and European subjects. There is concern that such data may not be appropriate for non-Western populations because of differences in metabolic costs. The present study addresses this concern by comparing measured vs. predicted energy costs at rest and during sub-maximal exercise in 83 subjects (52 males, 31 females) from three subsistence-level populations (Siberian herders and high-land and coastal Ecuadorian farmers). Energy costs at rest (i.e., lying, sitting and standing) and while performing a standard stepping exercise did not significantly differ among the three groups. However, resting energy costs were significantly elevated over predicted levels (+16% in men, +11% in women), whereas exercising costs were comparable to predicted values (?6% in men, +3% in women). Elevations in resting energy needs appear to reflect responses to thermal stress. These results indicate that temperature adjustments of resting energy costs are critical for accurately predicting daily energy needs among traditionally living populations. o 1996 Wiley-Liss, Inc. 相似文献
50.
We examined the applicability of radiotelemetry to studies of acorn dispersal byApodemus mice and compared its efficiency with the of this spool-and-line method. Installation of a transmitter (2.2 g) onto acorns
did not interfere with the transporting and feeding behavior of the mice. We were able to detect all transmitter-installed
acorns and follow the daily changes in the sites in which they were hoarded, while we missed 59% of the spool-tied acorns
due to mice breaking the threads. Mice carried transmitter-installed acorns farther than spool-tied ones. The radiotelemetry
method is superior to the spool-and-line method and useful for the study of hoarding behavior in rodents. 相似文献