Complementarity of genes for resistance to greenbug [Schizaphis graminum (Rondani)], biotype E,in sorghum [Sorghum bicolor (L.) Moench]

Summary Gene complementarity among various sources of resistance to greenbug biotype E was assessed. Analysis of the F₂ generation of crosses between susceptible and resistant parents (mating 1) and among sources of resistance (mating 2) suggested that resistance in sorghum to greenbug biotype E was complexly inherited and, to some extent, dependent on the nature of both the resistant and susceptible parents. Positive transgressive segregation in the F₂ generations of both matings was found to be due to effective plus factors, contributed by both parents in a cross, which complemented each other. The number of plus factors ranged from one to two in the susceptible parents and from two to five in the resistant parents of mating 1, and from one to five in the parents of mating 2. The consistently significant reciprocal effects shown by Sarvasi and PI264453 indicated that these sources had major factors for resistance in their cytoplasms, which were expressed in all their crosses. The results from this study indicated that the sources of resistance complemented each other to give increased number of F₂ segregates with increased resistance. Thus, it should be possible to increase and diversify resistance of sorghum to greenbug biotype E by accumulating different, effective plus factors from various sources through recurrent selection.Contribution No. 90-106-J from the Kansas Agricultural Experiment Station, Kansas State University, Manhattan, KS 66506, USA     

Studies of the relationship between isoprene emission rate and CO2 or photon-flux density using a real-time isoprene analyser

Abstract. Studies of the isoprene emission rate in response to changes in photon-flux density and CO₂ partial pressure were conducted using a recently developed on-line isoprene analyser combined with a gas exchange system and chlorophyll fluorometer. Upon darkening, the isoprene emission rate from leaves of aspen ( Populus tremuloides Michaux.) began to decline immediately, demonstrating that the internal pool of isoprene, or its precursors, is small and that the instantaneous emission rate is tightly coupled to the rate of synthesis. A post-illumination burst of isoprene was observed within 5 min after darkening and lasted for 15–20 min in four isoprene-emitting species that were examined. In leaves of eucalyptus ( Eucalyptus globulus Labill.), the magnitude of the post-illumination burst was dependent on the photon-flux density that existed before darkening, but not on ambient CO₂ partial pressure. The dependence of the post-illumination burst on photon-flux density paralleled that for the steady-state rate of isoprene emission. A step-wise increase in intercellular CO₂ partial pressure from 24.5 to 60 Pa resulted in an immediate decrease in isoprene emission rate and non-photochemical fluorescence quenching, but an increase in CO₂ assimilation rate. Given the several recent studies that link isoprene emission to chloroplastic processes, the results of this study indicate that the linkage is not dependent on the rate of CO₂ flux through the reductive pentose phosphate pathway, but rather on more complex relationships involving metabolites not appreciably influenced by CO₂ partial pressure.     

美洲蜚蠊机械感受器输出信号的计算机分析

对蜚蠊单个机械感受器诱发反应峰电位的历程及幅度,使用系列分析、栅分析、时序分布、累加密度函数、栅—频分析、特征参数的伪三维隐线显示、峰电位幅度概率密度函数、峰电位间隔概率密度函数等分析方法,获得较多的神经信号间隔编码信息,以揭示刺激和反应之间的复杂关系。峰电位间隔和栅—频分析图由函数经曲线拟合后,分别求得描述其动态过程的时间常数τ_1,τ_2和τ_3,应用上述多种分析显示方法,使研究者更为直观地观察和定量描述刺激—反应间的动态关系。     

神农架拐棍竹林的初步研究

拐棍竹(Fargesia spathacea Franch.)是中国特有分布种类,主要分布川、滇、陕、甘等省。是极有开发价值的植物资源,又是大熊猫取食主要竹种之一。本文研究了神农架拐棍竹林的生态生物学特点,客观地估算了其蕴藏量,进行了营养成分分析。现报道如下:     

Effects of naloxone-precipitated withdrawal after a single dose of morphine on catecholamine concentrations in guinea-pig brain

The effect of naloxone-precipitated withdrawal after acute morphine was studied on the concentrations of noradrenaline (NA), 4-hydroxy-3-methoxyphenylethyleneglycol (MHPG), dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), and on the metabolite/parent amine ratios MHPG/NA, DOPAC/DA and HVA/DA, in eight regions of the guineapig brain. Guinea-pigs were treated with a single dose of morphine sulphate (15 mg/kg s.c.) or saline (control) and 2h later with naloxone hydrochloride (15 mg/kg s.c.) to precipitate withdrawal. The animals were decapitated at 0.5 h or 1 h after naloxone injections and their brains analysed for monoamine concentrations by HPLC-ECD. At 0.5 h after naloxone-precipitated withdrawal NA and MHPG levels, and the MHPG/NA ratio, were increased in the hypothalamus, and the NA levels were increased in the hypothalamus, medulla/pons and cortex 1 h after naloxone. Naloxoneprecipitated withdrawal also produced increased DA metabolism in the cortex, midbrain and medulla 0.5 h later, and in the cortex, hypothalamus and striatum 1 h later. Hence naloxone-precipitated withdrawal from acute morphine treatment produced a complex pattern of increased synthesis and metabolism of NA and DA which varied over time and with the brain region examined.     

Nearshore and pelagic abundances of Artemia monica in Mono Lake,California

The spatial distribution and abundance of the brine shrimp, Artemia monica, in Mono Lake, California were determined during 1982 and 1983. Peak abundances of shrimp occur in midsummer and reach densities of 15–17 individuals l^-1 in the nearshore regions and 6–8 individuals 1^-1 in the pelagic region. The brine shrimp were non-uniformly distributed both vertically and horizontally. The coefficient of variation in shrimp abundance among stations within the nearshore region was similar to that found in the pelagic region. On two of the nine dates, nearshore densities were 3 to 4 times greater than those in the pelagic zone, and on average the brine shrimp appear to be slightly over-dispersed to the nearshore region. However, including nearshore abundances in lakewide estimates will usually result in a change of less than a 10%.     

On some freshwater harpacticois from Japan,closely related to Canthocamptus mirabilis Štěrba

Preliminary comparisons are presented, of certain diagnostic characters of four species of Canthocamptus, all the specimens examined here being collected from freshwater bodies throughout Japan. The geographical distribution of each species is also discussed.Contribution No. 69 from the Itako Hydrobiological Station, Ibaraki University.     

The species composition,occurrence and temporal stability of submerged aquatic macrophyte patches along the main channel border of pool 5A,Upper Mississippi River

Species composition, relative abundance, distribution and physical habitat associations of submerged aquatic macrophytes in the main channel border (MCB) habitat of Pool 5A, Upper Mississippi River (UMR) were investigated during the summers of 1980 and 1983. The submerged aquatic macrophytes in Pool .5A MCB were a small and stable component of the river ecosystem. Submerged plants occurred primarily in small, monospecific clumps. Clumps in close proximity to each other formed plant patches. Plant patches were stable in location and number between 1980 and 1983; 82.5% of the patches first observed in 1980 were present in 1983. Submerged macrophytes covered about 10–12 ha of the 201 ha MCB in Pool 5A. Submerged plants were most common in the lower two-thirds of the pool. Ten species of aquatic macrophytes occurred on rock channel-training structures and eleven occurred on non-rock substrates in the MCB. The most common submerged plants, in order of abundance, were Vallisneria americana Michx., Heteranthra dubia Jacq., Potamogeton pectinatus L., Ceratophyllum demersum L. and Potamogeton americanus C. & S.