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51.
棕色固氮菌在正常培养过程中所产生的含肽物质,有络合特征峰出现。含肽物质与钼(V)络合的EPR信号g值为1.94。与钼酸盐的络合稳定常数K为2.5×10~9。棕色固氮菌变种UW1(Av1~-,Av2~-),UW38(Av1~-,Av2~ )和UW91(Av1~ ,Av2~-)都能产生类似的含肽物质。培养基中钼的存在是含肽物质产生和分泌所必需的,含肽物质排出的量与培养基中钼的水准呈正相关。不能积累钼的变种UW71在高钼培养基中只能限量地分泌含肽物质。氨培养条件下仍能产生和分泌含肽物质。这种含肽物质与该菌粗提液中的某种成分(除固氮酶组分外)具同源性,它既能从菌体中分泌出来,又能进入菌体,在菌体和培养液之间往返运行,可能在该菌钼酸盐运输中起载体作用。 相似文献
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Summary Using the monotone dependence function (mdf) together with correlation coefficient it was found that the Ma-DNA content as well as total protein content are regularly, linearly, positively and strongly dependent in sister cells (proter-opisthe) ofChilodonella steini. Additionally it was shown that proter-opisthe ordering is irrelevant to Ma-DNA and protein contents.Analysis of sister cell generation times (TG) confirmed the existence of regular, linear, positive and strong codependence.The relations between Ma-DNA and total protein contents, between protein content and TG, and between Ma-DNA content and TG were also described. There is a weak, linear dependence between Ma-DNA and total protein contents. Relations of TG and Ma-DNA content or TG and total protein content are non-linear and not even monotone. Low and high levels of DNA or proteins are connected with long generation times. 相似文献
55.
Most previously published electromyographic (EMG) studies have indicated that the temporalis muscles in humans become almost
electrically quiet during incisai biting. These data have led various workers to conclude that these muscles may contribute
little to the incisai bite force. The feeding behavior and comparative anatomy of the incisors and temporalis muscles of certain
catarrhine primates, however, suggest that the temporalis muscle is an important and powerful contributor to the bite force
during incision. One purpose of this study is to analyze the EMG activity of the masseter and temporalis muscles in both humans
and macaques with the intention of focusing on the conflict between published EMG data on humans and inferences of muscle
function based on the comparative anatomy and behavior of catarrhine primates. The EMG data collected from humans in the present
study indicate that, in five of seven subjects, the masseter,anterior temporalis, and posterior temporalis muscles are very active during apple incision (i.e., relative to EMG activity
levels during apple and almond mastication). In the other two human subjects the EMG levels of these muscles are lower during
incision than during mastication, but in no instance are these muscles ever close to becoming electrically quiet. The EMG
data on macaques indicate that, in all six subjects, the masseter, anterior temporalis, and posterior temporalis muscles are
very active during incision. These data are in general agreement with inferences on muscle function that have been drawn from
the comparative anatomy and behavior of primates, but they do not agree with previous experimental data. The reason for this
disagreement is probably due to differences in the experimental procedure. In previous studies subjects simply bit isometrically
on their incisors and the resulting EMG pattern was compared to the pattern associated with powerful clenching in centric
occlusion. In the present study the subjects incised into actual food objects, and the resulting EMG pattern was compared
to the pattern associated with mastication of various foods. It is not surprising that these two procedures result in markedly
different EMG patterns, which in turn result in markedly different interpretations of jaw-muscle function. In an attempt to
explain the evolution of the postorbital septum in anthropoids, it has been suggested that the anterior temporalis is more
active than the masseter during incision (Cachel, 1979). The human and macaque EMG data do not support this hypothesis; during
incision, the two muscles show no consistent differences in humans and the masseter appears to be in fact more active than
the anterior temporalis in macaques. 相似文献
56.
Regulation of the loss of frost hardiness in Pinus radiata by photoperiod and temperature 总被引:2,自引:1,他引:1
Abstract. In controlled environments, the interactive effects of warm (16: 8°C, day: night) and cool (12: 4°C, day: night) temperatures and long (13.5 h) and short (10 h) photoperiods on the dehardening of seedlings of Pinus radiata D. Don were investigated. In another experiment, the effect of four photoperiods from 9 to 14 h was examined. In a third, dehardening at constant temperatures from 5 to 17°C was followed. There was no evidence for an interaction between photoperiod and temperature. Dehardening was temporarily delayed by photoperiods below about 10 h, but there was no other quantitative effect of photoperiod. At constant temperatures, the rate of dehardening was initially constant but declined as the minimum summer frost hardiness was reached. In the initial phase the rate of dehardening was a linear function of temperature, increasing from 0.05°C day−1 at 8°C to 0.30 °C day−1 at 17°C. Temperature controlled the loss of frost hardiness by regulating the rate of dehardening. 相似文献
57.
Synopsis Laboratory studies were conducted on 15 schools of blackchin shiners, Notropis heterodon, to determine if they altered their structure in response to changing environmental demands. The hypothesis tested was that fish schools should sacrifice a flat, hydrodynamically efficient structure in favour of an unobstructed visual field in the presence of a predator by staggering in the vertical plane. Ten schools were exposed for two weeks to a simple environment with only a current. For the next two-week period a predator was added. Five control schools were exposed to the simple environment for both two-week periods. Six of the ten treated schools increased their staggering in the vertical dimension as predicted while none of the control schools changed. This result was suggestive that hydrodynamic advantages were sacrificed. Respirometer experiments indicated these fish were capable of achieving some hydrodynamic benefits from schooling but these benefits may be a function of fish size. 相似文献
58.
A direct radioimmunoassay for measuring urinary 20-hydroxyprogesterone cross-reactivity to monitor and assess luteal function and detect pregnancy in the lion-tailed macaque (Macaca silenus) is described. Urine samples were collected daily during ten nonconceptive and five conceptive ovarian cycles of five dult female lion-tailed macaques. Urine was analyzed for concentrations of 20α-hydroxypro-gesterone cross-reactivity, estrone conjugates, and creatinine. The strength of the luteal phase in normal nonconceptive cycles (n = 8) is characterized by a maximum sevenfold increase (day 9) in mean 20α-hydroxyprogesterone cross-reactivity over follicular phase levels; the duration, by a 13-day sustained elevation of mean 20α-hydroxyprogesterone cross-reactivity levels. Pregnancy is detectable from 20α-hydroxyprogesterone cross-reactivity values approximately 20 days after the periovulatory estrone conjugate peak (n = 4). Apparent anovulation (n = 1), extended follicular phase (n = 1), and early abortion (n = 1) also are detectable using 20α-hydroxyprogesterone cross-reactivity measurements. 相似文献
59.
60.
应用酶联免疫吸附试验检测马铃薯卷叶病毒 总被引:2,自引:0,他引:2
以辣根过氧化物酶标记马铃薯卷叶病毒抗体,采用双抗体夹心ELISA方法鉴定了马铃薯和洋酸浆的茎、叶、根及马铃薯块茎中的马铃薯卷叶病毒(Potato Leafroll Virus,PLRV),结果表明,对提纯的PLRV可测出的最低浓度为25ng/ml,当包被抗体浓度为40μg/ml、酶标记抗体稀释度为1/120时,可测出马铃薯茎、叶和根汁液中的PLRV,感染PLRV的洋酸浆茎、叶和根汁液的消光值,均比无病对照者高二倍以上,虽然感染PLRV的马铃薯休眠块茎维管束组织汁液的消光值高于无病毒对照,且脐部维管束组织消光值高于顶端,但测定打破休眠的感病块茎顶端维管束组织的阳性结果更为可靠和明显。 相似文献