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81.
大鼠下丘脑室旁核神经元对电刺激蓝斑和中缝背核的反应 总被引:2,自引:2,他引:0
用玻璃微电极细胞外记录大鼠室旁核(PVH)神经元的单位放电,观察它对电刺激蓝斑(LC)和中缝背核(DR)的反应。 在435个被试验单位中,5个单位对LC电刺激呈现逆行反应,75个单位呈现顺行反应。在这75个顺行反应单位中,27个对单刺激发生反应,48个对串刺激发生反应。对电刺激DR发生反应的有74个单位,其中15个对单刺激发生反应,59个对串刺激发生反应而对单刺激不反应。值得注意的是有23个PVH神经元既对LG刺激又对DR刺激发生顺行反应。实验结果提示,PVH与LC、DR之间存在神经联系。 相似文献
82.
83.
A role for haemoglobin in all plant roots? 总被引:4,自引:2,他引:2
Abstract. We have found haemoglobin in plant roots whereas previously it has been recorded only in nitrogen fixing nodules of plants. Haemoglobin occurs not only in the roots of those plants that are capable of nodulation but also in the roots of species that are not known to nodulate. We suggest that a haemoglobin gene may be a component of the genome of all plants. The gene structure and sequence in two unrelated families of plants suggests that the plant haemoglobins have had a single origin and that this origin relates to the haemoglobin gene of the animal kingdom. At present we cannot completely rule out the possibility of a horizontal transfer of the gene from the animal kingdom to a progenitor of the dicotyledonous angiosperms but we favour a single origin of the gene from a progenitor organism to both the plant and animal kingdoms. We speculate about the possible functions of haemoglobin in plant roots and put the case that it is unlikely to have a function in facilitating oxygen diffusion. We suggest that haemoglobin may act as a signal molecule indicating oxygen deficit and the consequent need to shift plant metabolism from an oxidative to a fermentative pathway of energy generation. 相似文献
84.
Serum copper and zinc levels were determined in 20 healthy women and in 100 women with gynecological tumors. Malignant and
benign tumor cases were separated according to their postoperative, histopathological examinations. The stages of malignant
and benign tumors were also established histologically. Seventy benign and 30 malignant genital tumors (carcinoma of cervix
in situ, cervix, ovary endometrium, and vulva) of the patients were differentiated histopathologically.
The serum Cu/Zn ratios of patients were increased significantly from the control group (0.32±0.35) to the benign group (1.22±0.63)
and from the benign group to the malignant group (2.24±1.03). Nine of 30 malignant cases were determined as false negative
(30%) and 15 of 70 benign cases were determined as false positive (14.2%) according to the serum Cu/Zn ratios of patients.
Serum copper levels of 30 malignant and 10 benign tumor cases showed linear correlation with serum ceruloplasmin values. 相似文献
85.
John I. Yoder Joe Palys Kevin Alpert Michael Lassner 《Molecular & general genetics : MGG》1988,213(2-3):291-296
Summary As an initial step towards developing a transposon mutagenesis system in tomato, the maize transposable element Ac was transformed into tomato plants via Agrobacterium tumefaciens. Southern analysis of leaf tissue indicated that in nine out of eleven transgenic plants, Ac excised from the T-DNA and reintegrated into new chromosomal locations. The comparison of Ac banding pattern in different leaves of the same primary transformant provided evidnece for transposition during later stages of transgenic plant development. There was no evidence of Ds mobilization in tomato transformants. 相似文献
86.
87.
Summary We evaluated three methods for the analysis of functional response data by asking whether a given method could discriminate among functional responses and whether it could accurately identify regions of positive density-dependent predation. We evaluated comparative curve fitting with foraging models, linear least-squares analysis using the angular transformation, and logit analysis. Using data from nature and simulations, we found that the analyses of predation rates with the angular transformation and logit analysis were best at consistently determining the true functional response, i.e. the model used to generate simulated data. These methods also produced the most accurate estimates of the true regions of density dependence. Of these two methods, functional response data best fulfill the assumptions of logit analysis. Angularly transformed predation rates only approximate the assumptions of linear leastsquares analysis for predation rates between 0.1 and 0.9. Lack-of-fit statistics can reveal inadequate fit of a model to a data set where simple regression statistics might erroneously suggest a good match. 相似文献
88.
Dose responses of gibberellins 总被引:4,自引:0,他引:4
Per Nissen 《Physiologia plantarum》1988,72(1):197-203
To determine the response type, published data for the most widely used bioassays for gibberellins have been analyzed by means of a computer program for estimating sensitivity parameters, or by interpolation. The dose response data are almost uniformly subsensitive, i. e. more than an 81-fold increase in external gibberellin concentration is required for a change from 10 to 90% of maximal response (S90 /S10 ). Data for the interaction of gibberellins with artificial membranes are, in contrast, markedly ultrasensitive (S90 /S10 ± 10). This difference further strengthens the view that lipid structures do not function as receptors for gibberellins. Most of the subsensitive dose responses for gibberellins can be quite precisely represented by cooperative isotherms. However, available data are insufficiently detailed for an unequivocal choice among cooperative, multiphasic or more complex kinetics. 相似文献
89.
Maize (Zea mays L.) and ricebean (Vigna umbellata [Thumb.] Ohwi and Ohashi) were grown in intercrop and monoculture on Tropaqualf soils under rainfed conditions in Northern
Thailand yearly from 1983 to 1986. De Wit's replacement design was used to compare intercrops and monocultures with a constant
plant density equivalent to 80 000 maize or 160 000 ricebean plants ha−1. Combined nitrogen was applied at varying levels to 200 kg N ha−1. In the final two seasons the intercrop ratio of maize: ricebean was also varied. At the time of maize maturity intercrops
yielded upt 49 kg ha−1 more N in the above ground plant parts than the best monoculture. Dry matter, grain and nitrogen yield of maize and ricebean
in intercrop relative to their monoculture yields (RY, relative yield) were significantly greater than their respective share
of the plant population. Relative yield totals (RYT) for grain, dry matter and nitrogen were always greater than 1.
Nitrogen uptake per maize plant increased with progressive replacement of maize by ricebean plants. This increase was similar
to that obtained by applying combined N. Available soil nitrogen tended to decrease with increasing maize:ricebean ratio.
Increasing the maize:ricebean ratio increased the % of nitrogen derived from fixation in ricebean, the increase being equivalent
to that obtained by decreasing combined nitrogen application. Approximately the same amount of fertilizer and soil nitrogen
was taken up by maize plus ricebean in intercrop as the maize monoculture. The results suggest that the improved nitrogen
economy of the intercrop resulted from the strong competitiveness of maize in the use of mineral nitrogen and the enhancement
of nitrogen fixation in intercropped ricebean which made it less dependent on the depleted pool of soil nitrogen. 相似文献
90.
P. Bebeli A. Karp P. J. Kaltsikes 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1988,75(6):929-936
Summary Plants were regenerated from cultured immature embryos of two pairs of sister lines of triticale (X Triticosecale) cvs Rosner and Drira and five sister lines of rye (Secale cereale). The triticale lines differ in heterochromatic content of a particular rye chromosome (6R or 7R), while the rye lines differ in only one heterochromatic band. Variation in morphogenetic response was present between the triticale cultivars and between the rye lines. One of the rye lines (7RL+ +) showed a distinctive superior response in terms of somatic embryogenesis. These findings are discussed in relation to factors affecting morphogenetic response and genetic stability in culture. 相似文献