杨树苗期合理密度与合理密度线研究

 本文以加杨(Populus Canadensis),I—214(Populus euramericana(Dode)Guinier CV—214),中保14等杨树密度试验(1988—1991)为依据,分析了初植密度、竞争对生长的抑制作用,阐述了合理密度、合理密度范围、缓冲作用、上限合理密度线的形成过程。指出在双对数图上,上限合理密度线遵从Logistic分布(1nw=K/1+e(0.732·lnN-2.429),呈左侧伸展的S型曲线。该曲线可划分为近似于lnw一lnN直线的上中下三部分,其中间部分直线式的斜率为-1.5左右,称作合理密度直线式。对密度与生长的动态作了分析、概述与讨论。     

Heterochrony and sexual dimorphism in the pigtailed macaque (Macaca nemestrina)

Somatic growth is not a simple linear process with a constant rate of growth. The most successful attempts to quantify growth as a function of age or size have employed nonlinear techniques. Sexual dimorphism of primate growth, weight vs. age, was examined using nonlinear models with Sirianni and Swindler's ([1985] Growth and Development of the Pigtailed Macaque, Boca Raton, FL: CRC Press) growth data on the pigtailed macaque (Macaca nemestrina). The best fit of several exponential growth models was the Gompertz curve: Different multiple phase models were also fit, where each phase represents a distinct exponential component. The two-phase models proved to be the best (R² = .0.84 for females, 0.91 for males), suggesting that there are two growth spurts, one in infancy and one at puberty. The timing of the beginning and end of the first spurt is the same in males and females, but the rate, and value of the asymptote for this phase, is greater in males. The timing of the second spurt is earlier, and the rate of growth for this spurt is smaller in females than males. The sexual dimorphism in these species is not a simple rate change, but a complex interaction of timing and rate over the entire period of growth. It would be impossible to separate these entities with a linear, polynomial, or single-phase model of the data. While these data and results complement much of the existing work on adult dimorphism, they also emphasize the vital role that ontogenetic data have in elucidating the underlying evolutionary mechanisms that generate sexual dimorphism. © 1994 Wiley-Liss, Inc.     

Characterization of Bacillus strains from apple and pear trees in South Africa antagonistic to Erwinia amylovora

In order to find reasons for the absence of fire blight in most countries of the Southern hemisphere, bark samples from apple and pear trees in orchards of the Western Cape region in South Africa were extracted for bacteria which could be antagonistic to Erwinia amylovora. Screening was done in the late growth season and mainly Gram-positive bacteria were isolated. Approximately half of them produced growth inhibition zones on a lawn of E. amylovora. Most isolates were classified as Bacillus megaterium by microbiological assays and in API 50 test systems. They were visualized in the light microscope as non-motile large rods. These strains may not be responsible for the absence of fire blight in orchards, but they may indicate unfavourable climatic conditions for Gram-negative bacteria including E. amylovora. They may reduce the ability of E. amylovora to establish fire blight and could also be useful for application in biological disease control.     

Immunocytochemical demonstration of somatotropin-like and prolactin-like activity in the brain of Calamoichthys calabaricus (Actinopterygii)

Summary Cellular binding of anti-bSTH and anti-oPRL IgG is demonstrated in the brain and the pituitary gland of the African freshwater fish Calamoichthys calabaricus by means of the unlabeled antibody enzyme method at the light microscopic level. In the brain, somatotropin and prolactin are demonstrated in separate neurons in the preoptic area. The somatotropinergic and prolactinergic perikarya are distinct from those of the hypothalamic-hypophysial neurosecretory neurons, i.e., those stainable with aldehyde fuchsin presumed to be vasotocinergic and isotocinergic. The somatotropinergic and prolactinergic neuronal perikarya give rise to separate beaded axons which pass either ventroposteriorly into the infundibulum, terminating in the neurohypophysis, or ventro-laterally through the wall of the preoptic recess, terminating near the superficial capillary bed covering this part of the brain surface. Moreover, coarse dendrite-like processes of both kinds of immuno-reactive neurons extend towards, and end in, the third ventricle. Binding sites in the brain to antisera against hLH, hFSH, hTSH and anti-(1–24) ACTH IgG, all reactive in the pituitary, are not observed in the neurons confined to the preoptic area.Supported by the Danish Natural Sciences Research CouncilThe authors wish to thank Professor Dr K.G. Wingstrand, University of Copenhagen, Denmark, for placing two series of C. calabaricus at their disposal. They would also like to thank the National Institute of Arthritis, Metabolism and Digestive Diseases, Bethesda, USA, for the generous gift of antisera against the subunits of human LH, TSH and FSH, and likewise Dr L. Hummer, Glostrup Hospital, Copenhagen, Denmark, for the gift of the anti-(1-24)ACTH IgG     

The effect of cessation of growth on protein synthesis in a mutant of Chinese hamster ovary cells with a temperature-sensitive leucyl-tRNA synthetase

A temperature-sensitive mutant of Chinese hamster ovary cells with an altered leucyl-tRNA synthetase fails to grow and to incorporate amino acids into protein properly at or near the non-permissive temperature. This mutant was used to determine whether cessation of growth at the elevated temperature affected elongation factor EF-1, since the activity of EF-1 is markedly lower in non-growing cells in stationary phase than in rapidly-growing cells in exponential phase. Cell-free extracts prepared from cells maintained at 39°C for 24 h showed a marked decrease in the ability to translate natural mRNAs, compared to cells incubated at 34°C. However, the ability to translate poly(U), which requires elongation factor EF-1 (and EF-2), was not affected. Analyses of activities involved in the initiation of protein synthesis and in the activation of amino acids revealed that, with the exception of leucyl-tRNA synthetase, the rest of the components required for translation also appeared to be relatively stable even after 24 h at the elevated temperature. The effects of elevated temperature on cell-free extracts were also investigated. The results were similar to those obtained with intact cells; that is, except for leucyl-tRNA synthetase which was rapidly inactivated in vitro at 39°C, other aminoacyl-tRNA synthetases and translational components involved in chain initiation and elongation were relatively stable. Thus, no change in EF-1 activity was detected as a result of arrested cell growth, an inherent lability of the elongation factor, or metabolic degradation as a consequence of a rapid turnover rate in the absence of protein synthesis.     

高碳水化合物日粮对翘嘴红鲌生长、GK及GK mRNA表达的影响

探讨不同碳水化合物(CHO)水平对翘嘴红NFDA5生长、葡萄糖激酶(GK)及GK基因表达的影响.选用540尾(40.73±0.44)g翘嘴红鲌,随机分成为高CHO组、中CHO组、无CHO组,每组设三个重复,饲养8周,测定鱼体生长、血液指标、GK活性及GK mRNA水平等指标.结果显示,随着CHO添加量的增加,鱼体特定生长率与死亡率呈下降趋势,饵料系数刚好相反.摄食后,血糖先上升后趋于平缓,其中高CHO组相对高,无糖组低;血浆甘油三酯先上升后下降再上升又下降,其中高CHO组相对高,中CHO组最低;无CHO组血浆胆固醇、中CHO组HK活性、高CHO组GDH相对较低,其他各组在投喂后都呈先上升后下降.GK活性总体呈上升趋势,各组在禁食时,检测不到GK活性,饲料CHO含量越高,GK活性也越高,但是GK mRNA的水平与CHO含量并不呈线性关系.血糖、GK活性与GK mRNA的水平之间有一定的相关性,摄食高CHO饲料可诱导GK酶活性及基因的表达,造成持续高血糖,这可能不利于生长.     

不同植物脂肪源对吉富罗非鱼生长性能、肌肉脂肪酸和生理生化指标的影响

配制了6种等氮等脂的饲料饲喂(12.320.02) g的吉富罗非鱼8周, 探讨罗非鱼对不同脂肪源的利用效果,筛选出适合吉富罗非鱼的植物脂肪源。6种饲料中分别添加大豆油(SO)、棕榈油(PO)、棉籽油(CO)、菜籽油(RO)、磷脂(SL)和1:1:1:1:1大豆油-棕榈油-棉籽油-菜籽油-磷脂混合油(MIX)。结果显示: (1)菜籽油组特定生长率显著高于棕榈油组、棉籽油组、磷脂油组和混合油组(P0.05), 大豆油组显著高于棉籽油组和棕榈油组(P0.05)。菜籽油组饲料系数显著低于棉籽油组、磷脂油组和棕榈油组(P0.05), 与其他各组无显著性差异(P0.05); (2)肌肉脂肪酸明显受饲料脂肪源影响, 棕榈油组肌肉脂肪酸组成与饲料脂肪酸组成相关性最大(P0.05), 棉籽油组肌肉脂肪酸组成与饲料脂肪酸组成相关性最小(P0.05); (3)棕榈油组天冬氨酸转氨酶活性显著高于菜籽油组(P0.05)。棉籽油组高密度脂蛋白胆固醇含量和低密度脂蛋白胆固醇含量显著高于菜籽油组(P0.05), 大豆油组肝脏脂蛋白酯酶活性显著高于棉籽油组和菜籽油组(P0.05)。研究结果表明: 菜籽油、大豆油可以作为吉富罗非鱼饲料中良好的脂肪源, 棉籽油不利于吉富罗非鱼生长。     

Growth patterns of Juncus gerardi clonal populations in a coastal habitat

Juncus gerardi populations demonstrated a logistic growth curve during the colonization stage. Shoot production by vegetative multiplication was virtually continuous from December to June. Experiments suggested that the stabilisation stage of the demographic curve reflected water deficit. Taller, fertile, winter and early spring cohorts could be distinguished from shorter, infertile end of spring and beginning of summer cohorts. Shoot emergence began in March and terminated at the end of June, when water becomes a limiting factor due to a period of water shortage, typical of the thermo-atlantic climate. Spatial extension of populations was due to rhizome growth, which ceased during flowering.Flowering in May temporarily checked growth in shoot height of all emerged cohorts. No cost of reproduction was demonstrated concerning the rate of appearance of new shoots.Although fertile shoots were taller than vegetative shoots, their growth rates were significantly lower from April onwards. The tallest fertile shoots produced the most capsules.Energy allocation to seed production is the only possible means for long-term establishment of new genotypes, and vegetative multiplication appears as the principal source of recruitment of new modules in Juncus gerardi.Resource allocation patterns in this clonal species are discussed in relation to the ecological background in the concerned marshlands and with theoretical proposals derived from models of spatial colonization strategies in clonal plants.Nomenclature: follows Flora Europaea (Tutin et al., 1964ndash;1980).     

林下人参生理特性和生长与林内生态因子的关系

结合模拟试验,对林下人参的生理活动及生长过程与林内生态因子的关系进行 了观测研究．结果表明,林内光照、水分、温度等因子与林下人参生长的关系极为密切．一 般林内光照在中等条件下,即相对光照在１０～３５％左右．林分郁闭度约０．６～０．８,土壤含 水量在 ３５～４０％时人参生长最好;林下人参的物候进程及生长与温度的关系密切．林内 温度在５℃左右人参芽胞开始萌动,１５℃左右地上茎高生长进入速生期,６月上旬生长停 止．因此,人为调节各种生态因子在适宜的范围内有利于林下人参的生长．     

Growth factor effects on costal chondrocytes for tissue engineering fibrocartilage

Tissue-engineered fibrocartilage could become a feasible option for replacing tissues such as the knee meniscus or temporomandibular joint disc. This study employed five growth factors (insulin-like growth factor-I, transforming growth factor-beta1, epidermal growth factor, platelet-derived growth factor-BB, and basic fibroblast growth factor) in a scaffoldless approach with costal chondrocytes, attempting to improve biochemical and mechanical properties of engineered constructs. Samples were quantitatively assessed for total collagen, glycosaminoglycans, collagen type I, collagen type II, cells, compressive properties, and tensile properties at two time points. Most treated constructs had lower biomechanical and biochemical properties than the controls with no growth factors, suggesting a detrimental effect, but the treatment with insulin-like growth factor-I tended to improve the constructs. Additionally, the 6-week time point was consistently better than that at 3 weeks, with total collagen, glycosaminoglycans, and aggregate modulus doubling during this time. Further optimization of the time in culture and exogenous stimuli will be important in making a more functional replacement tissue.