Phenological growth stages of North American ginseng (Panax quinquefolius)

The BBCH (Biologische Bundesanstalt, Bundessortenamt, Chemische Industrie) scale is used to describe the phonological growth stages of North American ginseng (Panax quinquefolius). Eight principal growth stages for germination and bud development, leaf development (crop canopy), root and perennating bud formation, peduncle elongation and inflorescence development, flowering and fruit set, development of fruit, ripening of fruit and senescence, and 42 secondary growth stages are described. A practical use of the scale is proposed with reference to the timing of application of agrochemicals for disease control.     

多组多滞后区间系数定常非线性关联控制大系统的结构与关联鲁棒镇定(I)

建立了多组多滞后区间系数定常非线性控制系统的结构概念,采用鲁棒镇定的等价法,给出了具有扰动结构参数的多组多滞后区问系数定常非线性关联控制大系统的结构与关联鲁棒镇定,同时给出了扰动参数与滞后非线性项界线的估价公式。     

采后大蒜鳞茎的生理生化变化及其贮藏技术

采后大蒜鳞茎的生理生化变化及其贮藏技术刘淑娴,李月标,陈芳,张东林,蒋跃明（中国科学院华南植物研究所,广州５１０６５０）摘要大蒜鳞茎在室温下贮藏２个月后,胚芽开始生长．随着胚芽生长,呼吸速率、蛋白质和维生素Ｃ含量逐渐增高;而可溶性糖和干物质含量下降。...     

Gap formation and species diversity in Japanese beech forests: a test of the intermediate disturbance hypothesis on a geographic scale

To evaluate whether the intermediate-disturbance hypothesis applies on regional scales, the relationship between the species diversity and gap formation regime of beech forests was examined. The mean gap size and the variation of gap sizes showed no correlation with species diversity. The mean windstorm interval varied widely, but geographical trends, such as latitudinal gradient, were not observed. However, locations that sustained an intermediate frequency of disturbance had the highest species diversity. Although a latitudinal gradient of disturbance was not apparent, the intermediate-disturbance hypothesis was partly supported on a geographic scale. The most predictable model for species diversity was a multiple regression model composed of two factors, the windstorm interval and the cumulative temperature of the growing season. The fact that the temperature was of greater importance than the disturbance interval indicates that the most important factor in predicting forest species diversity is the amount of available energy on a geographic scale.     

Photoperiodic responses of a northern and southern ecotype of black cottonwood

Photoperiod is an important signal controlling the onset of dormancy in perennial plants. Short days typically induce growth cessation, the initiation of cold acclimation, the formation of a terminal bud. bud dormancy and other adaptive responses. Photoperiodic ecotypes have evolved in many species with large latitudinal distributions. The photoperiodic responses of two northern (53°35′ and 53°50′N) and two southern (34°10′ and 40°32′N) genotypes of black cottonwood (Populus trichocarpa Torr. & Gray) were characterized by growing trees under a range of photoperiods in the greenhouse and growth chamber. Short days induced bud set in both ecotypes. resulting in trees with fewer leaves and less height growth than trees grown under long days. Short days also enhanced anthocyanin accumulation in the northern ecotype and decreased branching of the southernmost genotype. Two aspects of the photoperiodic response were evaluated for each trail: critical photoperiod. which was defined as the longest photoperiod that elicited a short-day response, and photoperiodic sensitivity, which was defined as the change in response per unit change in photoperiod. For each of the traits analyzed, the northern ecotype had a longer critical photoperiod and greater photoperiodic sensitivity than did the southern ecotype. The short critical photoperiod and reduced photoperiodic sensitivity of the southern ecotype resulted in a significant delay in bud set compared to that of the northern ecotype, even under a 9-h photoperiod. Typically, photoperiodic ecotypes have been characterized as having different critical photoperiods. Ecotypic differences in photoperiodic sensitivity, however, indicate that differences in the photoperiodic response curves cannot be completely described by the critical photoperiod alone. These results also suggest that the critical photoperiod. photoperiodic sensitivity and speed of bud set have a common physiological basis. Bud set occurred earlier hi the northern ecotype primarily because bud scale leaves were initiated earlier. For one of the northern genotypes, leaf primordia that were initialed under long days subsequently differentiated into bud scale leaves after the trees were transferred to a 9-h photoperiod. This demonstrates that primordia initiated under long days are not necessarily committed to becoming foliage leaves. The response to photoperiod did not differ appreciably between the greenhouse and growth chamber conditions that were tested.     

Microcomputer interface for computer-controlled enzyme kinetic studies with the monolayer technique

Periodic acid oxidation in methanol followed by incubation with 1, 1-dimethylhydrazine results in release of diacylglycerols from 1,2-diacyl-3-glycosyl-sn-glycerols. During hydrazinolysis of oxidized monogalactosyl diacylglycerol, an intermediate hydrazone derivative was observed which was isolated and identified. The diacylglycerols recovered are 1,2-diacyl isomers containing the same fatty acid mixtures as the intact glycolipids. The yields of diacylglycerols released from plant monogalactosyl-, digalactosyl-, and sulfoquinovosyl diacylglycerols were in the range of 30-50%. The method may be used for analysis of molecular species and for preparative purposes.     

Studies on formation and resorption of fish scales

Summary Scale formation in Cyprinodon variegatus was found to be initiated at about 26 to 30 days after hatching. Ultrastructural investigation revealed that within 4 to 6 h in the first-formed scales the marginal cells begin to flatten and differentiate into osteogenic cells, which later change to osteoblasts and fibroblasts. These cells are separated from the surrounding epithelial cells by a basal lamina. The osteoid is formed by the marginal and osteogenic cells; the osseous layer by the osteoblasts; and the fibrillary plate by the fibroblasts.The osteoid is formed within 2 to 3 h after the initiation of the scale, and within 20 to 24 h the osseous layer is formed. Hydroxyapatite crystals are deposited in the matrix of the osseous layer without apparent association with collagen fibers. No matrix vesicles or dense bodies are evident at the sites of calcification. The fibrillary plate arises 18 to 20 h after the initiation of the scale. It is also partially calcified, but not before the third week of scale formation. The crystals develop almost exclusively between the collagen fibers at the extreme edge of the calcifying front, but solid calcification of the fibers results with further growth of the crystals. The fibroblasts appear to participate in calcification of the fibrillary plate.Contribution No. 332, Belle W. Baruch Institute for Marine Biology and Coastal Research, University of South Carolina, Columbia, South Carolina, 29208, USA     

通风结构林带背风面湍流相关特征初步分析

本文根据湍流统计理论和野外观测数据,详细分析了林带背风面湍流自相关、空间相关和湍流积分尺度特征。在林带背风面的林缘附近,由于湍流尺度较小,使湍流相关系数不紧密。这时的时间尺度在2—3s(1.5m)和3—8s(5m),而空间尺度为10—20m左右。在远离林带以后,林带的作用减弱,随着湍流尺度增大,导致湍流相关系数增大。这时的时间尺度在15—20s,空间尺度在70—80m范围内,且湍流自相关系数服从2/3的指数定律。     

Properties of Muscarinic-Stimulated Adenylate Cyclase Activity in Rat Olfactory Bulb

The muscarinic stimulation of adenylate cyclase activity in rat olfactory bulb was characterized, with the aim of elucidating the nature of the molecular mechanism involved. Carbachol (CCh) stimulated the enzyme activity in either crude or purified cell membrane preparations and increased cyclic AMP accumulation in miniprisms of olfactory bulb. The CCh stimulation of adenylate cyclase activity displayed a fast onset and was rapidly reversed by addition of atropine. The stimulation was associated with an increase in the apparent Vmax of the enzyme, with no change in the Km for Mg-ATP. The affinity of the enzyme for Mg2+ was enhanced by CCh. The muscarinic effect required GTP at concentrations higher than those needed for enzyme stimulation with either l-isoproterenol or vasoactive intestinal peptide. Moreover, contrary to the beta-adrenergic stimulation, the muscarinic effect disappeared when guanosine 5'-O-(3'-thiotriphosphate) was substituted for GTP. In vivo treatment of olfactory bulbs with pertussis toxin completely prevented the muscarinic stimulation of adenylate cyclase, whereas cholera toxin was without effect. These results indicate that in rat olfactory bulb muscarinic receptors increase adenylate cyclase activity by interacting with a pertussis toxin-sensitive GTP-binding protein different from the stimulatory GTP-binding protein.     

Neuroethology of olfactory preference development

Young mammals come to approach the odor of their mother, a response that facilitates their survival during early life. Young rats induce a cascade of events in their mother to induce the emission of her odor. The pups increase circulating prolactin levels, which increases food intake and the emission of large quantities of cecotrophe containing the maternal odor. This odor is synthesized by the action of cecal microorganisms and changes with maternal diet. The diet-dependence of the odor requires the pups to acquire their attraction to the odor postnatally. The acquisition of this preference occurs when an odor is paired with the tactile stimulation that pups receive during maternal care. The action of the tactile stimulation appears to be mediated by noradrenaline. The development of this type of olfactory attraction is accompanied by changes in the regions of the olfactory bulb that are responsive to the attractive odor. Metabolic, anatomical, and neurophysiological changes in response to the attractive odor emerge in such regions of the bulb after early olfactory preference training. © 1992 John Wiley & Sons, Inc.