银杏发展态势及其价值分析

银杏(Ginkgo Biloba L.)在中国有悠久的栽培历史。通过综合国内有关资料。从银杏的适应能力、应用价值和经济效益等方面，详尽阐述了近几年银杏栽培迅猛发展之原因，指明其发展趋势，给人们在今后的银杏栽培及开发利用方面以启迪。     

Beta adrenergic receptor localization in rat brain by light microscopic autoradiography

The characteristics of ³H-dihydroalprenolol (³H-DHA) binding to mounted tissue sections of rat brain were studied. The binding had all the characteristics of a beta-receptor. It was reversible, saturable (K_D 2.3 nM, B_max 23 fmol/mg tissue, wet wt) and was inhibited only by beta-adrenergic drugs. The forebrain binding had the properties of a beta-1 receptor, while cerebellar binding had beta-2 characteristics. Beta-adrenergic receptors were widely distributed in the rat brain. High concentrations were localized in the superficial layers of the neocortex, in the caudate-putamen, nucleus accumbens, olfactory tubercles, substantia nigra, nucleus interpeduncularis, subiculum and pia mater. Areas containing intermediate concentrations of receptors included the cerebellum, hippocampus and thalamus. Areas containing low concentrations of receptors included the hypothalamus, amygdala, brainstem and medulla. Co-incubation with low concentrations of zinterol to preferentially block beta-2 receptor resulted in an inhibition of most of the binding to the cerebellum and pia matter and produced only a small and generalized decrease in the rest of the brain. Beta receptors were found in many areas known to contain noradrenergic nerve terminals. Paradoxically some areas with high densities of dopaminergic nerve terminals, had high densities of receptors. Results of electrophysiologica and lesion studies are also discussed.     

The mechanism of inhibition and "reversal" of mitogen-induced lymphocyte activation in a model of purine-nucleoside phosphorylase deficiency

Purine-nucleoside phosphorylase (PNP) is a purine degradative enzyme that catalyzes the phosphorolysis of (deoxy) inosine or (deoxy) guanosine to their respective bases and (deoxy) ribose 1-phosphate. A severe T-cell immune deficiency syndrome with hypouricemia is associated with impaired PNP function. To study the biochemical basis for this syndrome we created an in vitro model of PNP deficiency in mitogen (phytohemagglutinin)-stimulated normal human peripheral blood lymphocytes using guanosine to competitively inhibit deoxyguanosine phosphorolysis. Guanosine-induced guanine toxicity was reversed by adenine. Under these conditions, deoxyguanosine (5-45 microM) diminished mitogen stimulation to 30% of control while increasing the deoxyguanosine triphosphate pool (dGTP) by over 20-fold. Deoxycytidine reversed deoxyguanosine toxicity with a diminution of dGTP accumulation, but no significant change in the deoxycytidine triphosphate pool. Thymidine reversed the deoxyguanosine toxicity, repleted the thymidine triphosphate (dTTP) pool, and caused an even further increase in the accumulation of dGTP. These data support a model of lymphotoxicity in PNP deficiency based on dGTP accumulation with inhibition of ribonucleotide reductase and depletion of the thymidine triphosphate pool. Thymidine triphosphate depletion is reversed by either deoxycytidine or thymidine; however, the former diminishes dGTP accumulation (probably by competition for phosphorylation) and the latter potentiates dGTP accumulation (probably through feedback augmentation of guanosine diphosphate (GDP) reduction by ribonucleotide reductase secondary to an increased dTTP pool).     

Improved method for ribonuclease zymogram

An improved method for ribonuclease zymogram in agarose overlays is described which enables significantly enhanced sensitivity and the avoidance of false-positive activity. Two critical aspects of the zymogram method—the fixation/staining technique and the RNA substrate concentration—were evaluated for the RNase activity in RNase A and in human serum and urine. The zymogram method is sensitive to at least 10 pg of RNase A and does not show a false-positive reaction from 1500 μg of non-RNase protein following electrophoresis in thin-layer polyacrylamide gel.     

Cholinergic muscarinic stimulation of steroidogenesis in bovine adrenal cortex fasciculata cell suspensions

Acetylcholine was found t acutely stimulate cortisol production by bovine fasciculata adrenocortical cell suspensions. This effect was maximal at 10^?4 M acetylcholine concentration, resulted in a 5-fold increase in cortisol production over the control after 1 h incubation, and represented about one fifth of the ACTH maximal stimulation under the same conditions. Acetylcholine-stimulated steroidogenesis was concentration-dependent (10^?8–10^?5 M), propotional to the cell numbe (5 · 10⁵–2 · 10⁶) and reached a plateau after 30 min incubation. Use of various cholinergic specific agonists and antagonists showed that thet steroidogenic action of acetylcholine was a typical muscarinic effect. This character is in agreement with the previously demonstrated presence of muscarinic receptors in bovine adrenocortical tissue. The steroidogenic effect of acetylcholine required the presence of extracellular calcium in the medium and was impaired upon addition of tetracaine and procaine. No change in cyclic AMP nor cyclic GMP levels could be detected in the system under acetylcholine stimulation. Acetylcholine appeared to exhibit a synergistic in combination with ACTH, and exogenous cyclic AMP; these observations suggest a different mechanism of action for acetylcholine and ACTH and point to a possible cholinergic participation in the regulation of adrenocortical differentiated functions in vivo.     

The histology and fine structure of the olfactory organ of the squid Lolliguncula brevis Blainville.

The olfactory organ of the squid has a thick, pseudostratified epithelium containing five morphological types of ciliated receptors. In the simplest receptors the cilia originate separately in the distal pole of the cell. All other receptors have some type of cilia filled cavity, varying from a simple pocket of cilia at the surface to a completely closed vesicle filled with cilia in cells deep in the epithelium. The receptors are compared to cells in the rhinophore of Nautilus and the olfactory organs of coleoid cephalopods. Possible functions of the olfactory organ, based on its morphology, are discussed.     

Studies on the effect of 3,4-dehydroproline on collagen metabolism in carbon tetrachloride-induced hepatic fibrosis.

The lectin from Euonymus europeus seeds was purified by adsorption onto insoluble polyleucyl hog A + H blood group substance and subsequent elution with lactose. The isolated lectin formed three lines in immunoelectrophoresis against rabbit antisera to the crude seed extract and showed three components on electrophoresis in acrylamide gel at pH 9.4. In analytical isoelectric focusing the purified lectin had six closely spaced bands with pI from 4.3 to 4.7. It sedimented as two peaks: a big symmetrical peak with s_20,w⁰ of 7.8 and another small, diffuse moving peak. The intrinsic viscosity was 0.057 dl/g and the M_r calculated from the sedimentation coefficients, intrinsic viscosity, and V? of 0.71 was about 166,000. In sodium dodecyl sulfate, it gives subunits of M_r 17,000 and 35,000; 20% of the 35,000 subunit resists reduction by dithiothreitol in 7 m guanidine-HCl. The Euonymus lectin is a glycoprotein containing 4.8% d-galactose, 2.9% d-glucose, and 2.8% N-acetyl-d-glucosamine. The purified lectin precipitated well with B and H blood group substances and with the P1 fraction of blood group B substance but not with A₁ substances. It precipitated poorly with Le^a and Le^b and precursor I blood group substances. Inhibition of precipitation with milk and blood group oligosaccharides showed the lectin to be most specific for blood group B oligosaccharides having the structure: dGalα1 → 3[lFucα1 → 2]dGalβ1 → 3 or 4dGlcNAcβ→. It is also inhibited by blood group H oligosaccharides but to a lesser degree. For 50% inhibition of precipitation, 3.5, 850, and 290,000 nmol of B and H oligosaccharides and lactose, respectively are required. The B and H specificities are an intrinsic property of a single lectin site since absorption and elution from an H immunoadsorbent gave material with B as well as H specificity. Millipore-filtered crude extracts of Euonymus europeus preserved with 0.02% sodium azide are stable in the refrigerator for many months and can be used for quantitative precipitin and for quantitative inhibition assays, results being the same as with purified lectin.