海南岛尖峰岭热带林土壤渗透水的初步研究

 本文应用开口托盘式集水器收集不同土层的渗透水,研究尖峰岭热带山地雨林,半落叶季雨林及其游耕地的土壤渗透水状况,分析了不同植被—土壤类型与利用状况的渗透特点、降水与渗透水的关系、渗透水量与水质的动态变化,初步揭示了尖峰岭热带林对水分的输导—涵贮性能,及热带林生态系统中物质迁移的特点,并据此分析了游耕农业的生态恶果。     

幼龄小白鼠全脑5SrRNA的全核苷酸序列测定

<正> 5S rRNA是一种稳定的独立小分子,在原核和真核细胞中都牢固地结合在核糖体的大亚基上。它在蛋白质生物合成过程中具有重要作用。微生物、大鼠肝细胞及某些植物细胞5S rRNA的一级结构都已经测定,脑细胞5SrRNA的一级结构尚未见报道。因此,我们对幼龄小鼠全脑5S rRNA的序列进行了分析。我们用辜祥荣等人的方法分离和纯化5S rRNA,5S rRNA3′-末端标记参照Peattie的方法(2)。3′-末端标记5S rRNA的序列分析用化学降解-凝胶直读法及特异RNa8e降解直     

Hemodynamic interactions between intrinsic blood flow control mechanisms in the rat kidney

In order to reconcile the controversial concepts of myogenically and tubuloglomerular-feedback (TGF)-mediated control of renal vascular resistance, a hypothesis is advanced according to which both mechanisms interact hemodynamically because of their serial arrangement. Whereas the myogenic mechanism is suggested to be localized in the more upstream segments of the preglomerular resistance vessels, the TGF mechanism is assumed to control the pre- and/or postglomerular vascular segment(s), close to the glomerular vascular pole. The efferent vascular resistance, however, is assumed to function generally akin to a 'passive' flow resistor. These assumptions together with elementary hemodynamic considerations, allow formulation of a simple renal hemodynamic model whose quantitative predications regarding the characteristics of RBF, GFR and TGF control are remarkably consistent with the literature: (1) the magnitude of TGF response is mainly dependent upon the myogenic cooperative amplification and (2) although the TGF mechanism is not involved in the autoregulative control of RBF and GFR, changes of the TGF function may shift the autoregulation curve to higher or lower RBF and blood pressure levels.     

Shoot-bud regeneration in subcultured callus of engelmann spruce

Summary Callus cultures ofPicea engelmannii (Parry, Engelmann spruce) were initiated and established from mature embryos cultured on von Arnold and Eriksson’s medium (AE) supplemented with N⁶-benzyladenine (10μM) and naphthalene acetic acid (10 μM). Cultures were maintained by subculture at 3-to-4-wk intervals. After three subcultures, callus was transferred to AE medium with only N⁶-benzyladenine (25 μM). Adventitious buds appeared on the surface of the callus after 2-to 4-wk and grew to adventitious shoots on AE medium without growth hormones or on AE medium with kinetin (0.1 μM). Shoot-forming capacity was maintained through 7 further subcultures. This study was supported by the Natural Sciences and Engineering Research Council of Canada grant G1438 to T. A. Thorpe and D. I. Dunstan.     

Restriction analysis of Thiobacillus ferrooxidans DNA using pulsed field electrophoresis]

The DNA of Thiobacillus ferrooxidans digested by any of the five restriction endonucleases (DraI, EcoRI, Eco321, HindIII, XbaI) was studied by electrophoresis in the pulsating differently directed electric fields (PF). The influence of PF conditions on the sized row of the divided DNA fragments was studied. Only the XbaI restriction endonuclease was shown to cleave the Thiobacillus ferrooxidans DNA into a number of fragments permitting one to define the sizes of fragments and genome (no more than 2300 bp). The prospects of using the restriction analysis of Thiobacillus ferrooxidans wild type culture for improving its properties in obtaining heavy metals are discussed.     

Lesion and regeneration in the medial cerebral cortex of lizards.

The cerebral cortex of Squamate reptiles (lizards and snakes) may be regarded as an archicortex or "reptilian hippocampus". In lizards, one cortical area, the medial cortex, may be considered as a true "fascia dentata" on grounds of its anatomy, connectivity and cyto- chemo-architectonics of its main zinc-rich axonal projection. Moreover, its late ontogenesis and postnatal development support this view. In normal conditions, it shows delayed postnatal neurogenesis and growth during the lizard's life span. Remnant neuroblasts in the medial cortical ependyma of adult lizards seasonally proliferate. The late-produced immature neurocytes migrate to the medial cortex cell layer where they differentiate and give off zinc-containing axons directed to the rest of cortical areas. This results in a continuous growth of the medial cortex and its zinc-rich axonal projection. Perhaps the most important characteristic of the lizard medial cortex is that it can regenerate after having been almost completely destroyed. Recent experiments in our laboratory have shown that chemical lesion of its neurons (up to 95%) results in a cascade of events; first, those related with massive neuronal death and axonal-dendritic retraction and, secondly, those related with a triggered neuroblast proliferation and subsequent neo-histogenesis, and the regeneration of an almost new medial cortex that shows itself undistinguishable from a normal undamaged one. This is the only report to our knowledge that an amniote central nervous centre may regenerate by new neuron production and neo-histogenesis. Perhaps the medial cortex of lizards may be used as a model for neuronal regeneration and/or transplant experiments in mammals or even in primates.     

Comparative effectiveness of various antibiotics in the treatment of patients with meningococcal meningitis]

The results of treating 322 patients with various forms of meningococcal infection accepted to a hospital within a year are presented. The patients were divided into 3 groups by the character of etiotropic therapy. The patients of group I were treated with benzylpenicillin and those of group 2 were treated with levomycetin sodium succinate. Group 3 included the patients, the therapy of whom with the above two antibiotics failed and they were subjected to treatment with cefazolin, cefotaxime, amikacin and other broad spectrum antibiotics. Benzylpenicillin generally proved to be the drug of choice in the antibacterial therapy of meningococcal infection. In comparison to levomycetin (chloramphenicol) it provide more rapid clinical recovery of the patients and normalization of the indices of the cerebrospinal fluid. Only failure of benzylpenicillin therapy was considered as an indication to the broad-spectrum antibiotics to be in the complex treatment of the patients. As additional methods for estimating the efficacy of antibacterial therapy it was recommended to employ calculation of the integral indices of hemograms (the leukocyte index of intoxication and the hematologic index of intoxication).     

Protein synthesis in the hippocampus associated with memory facilitation by corticotropin-releasing factor in rats.

The present study used pharmacological, biochemical, and behavioral methods to examine the role of protein synthesis in the hippocampus in memory processes of a passive avoidance learning in rats. Results indicated that corticotropin-releasing factor (CRF) significantly improved memory retention in rats. Both cycloheximide (CHX) and actinomycin-D (ACT-D) impaired memory at high doses. At doses of CHX and ACT-D that did not affect memory alone, they both antagonized the memory-enhancing effect of CRF. Biochemically, there were specific increases in the optical density of three protein bands in the cytosolic fraction of hippocampal cells in rats showing good memory. There were also marked increases in the optical density of two protein bands in the nucleus fraction of the same animals. Similar results were observed in animals injected with CRF. However, no significant protein alteration was observed in animals receiving stress. These results together suggest that there are new protein syntheses in the hippocampus that are specifically associated with passive avoidance learning in rats.     

Current methods for the laboratory diagnosis of campylobacteriosis]

An analytical review of recent publications of home and foreign authors on the problem of laboratory diagnosis of campylobacteriosis is presented. The commercial nutrient media, methods of creation of the microaerophilic conditions for cultivation of campylobacter are presented. The filtration method is preferable for isolation of these agents from the studied material highly contaminated by accompanying microflora. A special attention is paid to immunodiagnosis of campylobacteriosis: agglutination reaction, coagglutination reaction, passive hemagglutination reaction, immunoenzyme and radioimmune analyses. Seroepidemiological examination of the staff at one of meat-packing factories in the Republic carried out by the method of indirect immunoenzyme analysis has revealed high levels of anticampylobacteriosis antibodies in 17.9% of examinees. The promising trends in perfection of the methods for laboratory diagnosis of campylobacteriosis are outlined.     

Functional asymmetry of the brain and effectiveness of sensorimotor function of oral cavity organs]

It has been established that in healthy persons functional brain asymmetry positively influences the effective performance of sensomotor function of oral cavity organs. Individual brain asymmetry is of considerable importance, the higher it is, the quicker the final results of sensomotor function are achieved. The character of brain asymmetry (right hand or left hand) does not practically influence the performance of sensomotor functions.