Summer bacterial populations in Mississippi River Pool 19: implications for secondary production

Bacterial populations were sampled at 37 sites in Mississippi River Pool 19. Bacterial biomass was calculated from direct epifluorescent cell counts. Bacterial production was estimated by incubating cells in situ in predator-free water inside membrane chambers and the frequency of dividing cells. Bacterial biomass in the water column ranged from 0.05 to 1.13 mg C ^-1, biomass in the vegetated areas of the pool was significantly higher than that in other habitats (P < 0.05, ANOVA). Biomass in sediments (to a depth of 10 cm) ranged from 24 to 1,073 mg C m^-2, biomass in muddy sediments was significantly higher (P < 0.05) than that in sandy sediments. Biomass on the submersed surfaces of hydrophytes was 0.06–4.90 mg bacterial C g^-1 dry weight of plant material. The vegetated habitat (water column plus vegetation) contained approximately 45 times the concentration of bacterial carbon found in nonvegetated main channel border areas and more than 100 times the concentration in the main river channel.Bacterial production rates in the water column of a vegetated section of the pool ranged from 0.03 to 3.28 g C m ^-3 s d ^-1 ; production (m ^-3) in a vegetation bed was 5.5 times that in the adjacent nonvegetated channel border areas and approximately 50 times that in the main channel. Aquatic macrophytes and associated microorganisms may be capable of providing significant inputs of carbon to secondary consumers in the pool during the summer low flow.     

Abundance and diversity of planktonic rotifers in the Po River

Zooplankton samples from the middle reach of the Po River were collected daily from 27 July to 24 August 1988 from a station located near Viadana. Changes in the biocoenosis structure were analyzed in relation to variations in flow rate. Rotifers accounted for more than 99% of the total zooplankton (protozoans excluded) in every sample. The dominant species were Brachionus calyciflorus, Brachionus bennini, Brachionus budapestinensis and Epiphanes macrourus. Under scanty flow conditions, the taxocoenosis showed marked stability. An increase in flow rate acts as a disturbance factor leading to a significant decrease in both total density and dominance.     

广西百色盆地更新世樟科两种植物角质层研究

本文描述的具角质层的两块叶化石,产自广西百色盆地更新统长蛇岭组。经与现代植物的角质层对比研究后,确定这两块叶化石分属于樟科的两属两种,即油丹(近似种)(Alseoda-phne cf.hainanensis Merr.)和紫楠(近似种)[Phoebe cf.sheareri(Hemsl.)Gamble]。研究结果表明,角质层在鉴定被子植物化石中具有可靠的价值。     

昆都仑鱼(Kuntulunia)的新材料及其系统位置的讨论

本文根据对宁夏六盘山群马东山组的长鳍昆都仑鱼(Kuntulunia longipterus, Liu, Ma et Liu 1982)的新材料的研究,对其形态特征做了一些补充和订正。在此基础上,笔者支持刘宪亭等人将昆都仑鱼归入华夏鱼科(Huashiidae)及华夏鱼科归入骨舌鱼类的观点。并且认为华夏鱼类代表了一新的亚目——华夏鱼亚目(Huashioidei subordo. nov.)。     

异育淇鲫及其双亲同工酶的比较研究

用4.5％聚丙烯酰胺凝胶平板电泳研究了异育淇鲫及其母本淇鲫和父本兴国红鲤的肌可溶性蛋白以及肾、肝、眼、背白肌和心等五种组织的乳酸脱氢酶(LDH)、苹果酸脱氢酶(MDH)和酯酶(EST)。结果发现:异育淇鲫的肌可溶性蛋白以及同工酶的电泳图谱与母本淇鲫相同而与父本兴国红鲤显著不同,因而认为异育淇鲫是淇鲫雌核发育的产物,父本基因对子代基本无影响。在此基础上,本文对异源精子在雌核发育中所起的生物学作用进行了初步探讨。     

Lampetra (Eudontomyzon) gracilis,a synonym of Eudontomyzon danfordi

Synopsis Evidence is presented which suggests that the nonparasitic lamprey, Lampetra (Eudontomyzon) gracilis Kux, 1965, is conspecific with the parasitic lamprey Eudontomyzon danfordi Regan, 1911. The diagnostic characters of the holotype and of the non-type material of E. gracilis are features found in E. danfordi specimens in their second and final year of adult life, thereby making the former a junior synonym of the latter.     

MASTODONT REMAINS FROM THE MIOCENE OF JUNGGAR BASIN IN XINJIANG

<正> The mastodont materials described in the present paper, associated with Amblycastor tunggurensis, Amphicyon sp., Anchitherium cf. aurelianense, Brachypotherium sp., ?Chilotherium sp., Stephanocemas thomsoni, Dicrocerus grangeri, Eotragus sp., Oioceros grangeri and O. noverca, were collected from the Haramagai formation of Junggar Basin in Xinjiang by an IVPP field team in 1982. The geology of the area has already been reported by Tong (1986, 1987). The mastodont fossils found at 5 sites on the north and west banks of the Ulungur river, Junggar Basin are abundant. They comprise 5 species, among which is one new species.The author is greatly indebted to the IVPP field team (Tong, Y., the head of the 1982 Junggar field team) allocating the mastodont materials for me to study.     

污水和污水土地处理系统中各种水质对华西蟾蜍蝌蚪红细胞微核率的影响

本文使用蝌蚪红细胞微核率作为指示器研究明通河污水和用污水土地处理系统处理后水质的致突变性。蝌蚪在各种水样品中暴露7天。采心脏血制片。在对照组中,微核率分别为4.40‰和4.68‰。1/4明通河污水组诱发蝌蚪的微核率是17.01‰。同对照组相比有明显的差异。     

柴达木盆地荒漠土壤蓝藻群落的初步研究

本文分析了柴达木盆地东部和中部具有代表性地区的丘陵、戈壁和沙丘的蓝藻种类组成、生物量及主要的土壤化学成分;采用了模糊聚类、系统聚类及多元线性回归等方法分析藻类的群落及其与环境因子的关系。共鉴定出21种蓝藻,其中6种为国内首次报道。研究表明:土壤含磷量、总盐量及与粘性和湿度有关的土壤结构是决定柴达木盆地蓝藻群落组成的重要因素。     

松辽盆地阿尔必期微体浮游植物新属种

该文描述了松辽盆地中白垩世阿尔必期泉头组三段的微体浮游植物化石1新属7新种,隶属于微咸水沟鞭藻类2属5新种(含4新亚种),淡水绿藻1属1种和疑源类1新属1新种。并对沟鞭藻 Ngktericysta Bint,1986进行了修订。