NITROGEN LIMITATION IN ISOCHRYSIS GALBANA (HAPTOPHYCEAE). I. PHOTOSYNTHETIC ENERGY CONVERSION AND GROWTH EFFICIENCIES1

The effect of steady-state nitrogen limitation on photo-synthetic characteristics and growth efficiency was examined in the marine haptophyte Isochrysis galbana Green. Nitrate limited chemostats were maintained at nine dilution rates, ranging from 0.18-0.96 d^?1, under continuous irradiance levels of 175 μmole quanta·m^?2·s^?1, an irradiance level which saturated photosynthesis at all growth rates. Nitrogen limitation led to an overall reduction in pigmentation and a decrease in the cellular concentration of reaction centers; however, the optical absorption cross section, normalized to Chl a, increased. Moreover, Chl c/a ratios were higher in nitrogen-limited cells: the change in Chl c/a ratios were correlated with an increase in the functional size of Photosystem II. Both light saturated photosynthetic rates normalized per cell and specific respiratory losses were positively linearly correlated with growth rate. Light saturated photosynthetic rates normalized to Chl a remained relatively insensitive to the rate of nitrogen supply. The minimum quantum requirement for gross photosynthetic oxygen evolution increased from 12.4 to 17.0 quanta/O₂. At the growth irradiance, the quantum requirement increased 88%, from 19.9 to 37.5 quauta/O₂ Photosynthesis/respiration ratios remained relatively constant at dilution rates greater than 35% of the maximum relative growth rate. Consequently, net growth efficiency, defined as the ratio of the specific growth rate, μ, to specific gross photosynthesis, P, also remained relatively constant over this range of growth rates averaging 85 ± 3%.     

HETEROTROPHIC SLIMES IN FLOWING WATERS

1. While much attention has been paid to the ecology of macro-invertebrates in flowing water, the microbial ecology of such systems has been largely ignored and our knowledge of heterotrophic slimes in particular remains far from complete. Slime-forming organisms are ubiquitous in their distribution and are part of the normal riverine flora. Slime outbreaks occur in all types of organically enriched flowing fresh waters, regardless of their chemical nature. Slimes are predominantly of heterotrophs which require a constant supply of (i) a suitable carbon source, (ii) inorganic nutrients and in particular nitrogen and phosphorous, and possibly (iii) growth factors such as vitamins. Phosphorous is not a limiting factor for growth, with slimes developing in rivers with < 0·02 mg P l^-1. Other inorganic nutrients such as nitrogen can be used in various forms and are usually present in adequate amounts, even in unpolluted streams. Therefore occurrence appears to be most closely correlated with the presence of a source of available carbon. 2. The severity of outbreaks are not closely associated with soluble organic carbon content although there is a tendency for heavy growths to occur more frequently in more severely polluted waters. Low-molecular-weight sugars are clearly the causative agents of Sphaerotilus natans dominated slimes with higher molecular weight material such as starches not immediately effective as growth promoters. Mono- to penta-saccharides are mainly used by bacterial slimes while fungal components utilize fatty acids up to C₈. It is not possible to adopt a nationwide BOD₅ standards to control slime outbreaks as even small increases in river BOD₅ (< 1·0 mg l_-1) can support slime growth. There is a need to develop new methods of assessing the slime-promoting capability of effluents such as measuring the readily degradable low-molecular-weight carbon compounds, so that threshold concentrations of soluble organic carbon below which slime will not develop can be determined. 3. The effect of effluent enrichment on slime growth diminishes downstream as there is a tendency for the soluble carbohydrate to mix and dilute. The slime also metabolizes the carbohydrate, reducing the concentration by up to 60 % depending on the stage of slime development, thus limiting its own proliferation. This is the typical pattern of self-purification in flowing waters. 4. The taxonomy of all the slime-forming species are poorly understood as is the ecology of slimes. Species composition of slimes vary temporally and spatially within individual rivers. The primary factors affecting composition are nutrient type and water velocity, although pH determines whether a slime is either predominantly fungal or bacterial. The rate of transfer of oxygen and nutrients is dependent on water velocity with zoogloeal forms predominating as velocity falls to < 0·05 m s_-1. More details of the effects of water velocity and other environmental factors on all the slime-forming organisms is required. 5. The effects of specific environmental factors on slime growth have been determined primarily from laboratory-based studies, often using pure cultures on solid medium or batch culture methods. Clearly it has been difficult to relate these results to what is happening in the field. Little quantitative information on the productivity of slimes exist and the energy budgets or role of slimes in the self-purification process of rivers is largely unknown. The effects of temperature, pH, dissolved oxygen concentration, water velocity, solar energy input and grazing on the relationship between organic nutrient concentration and slime growth needs to be fully understood. Therefore there is a need for both field-based flow channel and field studies using mixed slime populations to accurately model the effects of environmental factors on slime development. Formation of such models is a prerequisite to the development of control strategies. 6. Due to slower oxidation rates at lower temperatures and reduced sloughing resulting in more luxuriant growths, slimes are generally considered to be more frequent and extensive in winter. However this is clearly not the case with outbreaks far more abundant in the summer due to the smaller flows reducing the dilution factor of effluents, and the enhanced temperature and suppressed oxygen concentration of the water, reducing competition and grazing. 7. The presence of slimes is not always detrimental, the major effect is unsightly appearance and reduced amenity value. Slime-forming organisms are predominantly aerobic and the rate of oxygen consumption of slimes is directly related to the dissolved oxygen concentration of the water. It would appear that slimes rarely cause deoxygenation, although sudden increases in water temperature which lowers the solubility of oxygen or enhanced chemical oxygen demand of the effluent due to reduced dilution, may cause total oxygen utilization. 8. The effects of slime growths on the aquatic environment are numerous and cumulative, especially in relation to salmonid fisheries. Nearly all pollutants that are released into the environment will enter surface waters at some stage, so the ability of heterotrophic slimes to rapidly accumulate heavy metals and perhaps other pollutants by various sorption processes will result in metals being concentrated and transferred along the food chain. This will eventually result in increased residual metal concentrations in fish or toxic concentrations of metals being accumulated in macro-invertebrates normally eaten by fish. Metals can be transported out of the polluted zone via sloughed floes and be released back in to solution downstream of the site originally affected. 9. The severity of problems associated with outbreaks increase with the length of the slime growth, with the majority of the longer outbreaks (> 5 km) resulting in oxygen depletion, increased siltation, alteration in flow pattern, increase in sloughed biomass, reduction in species diversity, destruction and reduction in habitat diversity and the elimination of fisheries. Case studies on the effects of slime growth, especially those causing fish kills, need to be carefully analysed and published. 10. The potential of heterotrophic slimes in biotechnology and wastewater treatment has yet to be fully realized. The ability to grow rapidly, producing considerable biomass rich in protein could be utilized. The sorption of heavy metals by all the slime-forming organisms but especially by the iron and manganese bacteria, could be used for the removal of low concentrations of metals in wastes, treatment of metal-rich effluents or for metal recovery. The property of removing phosphorous and nitrogen from solution should also be further considered. 11. No adequate control measures are available except for full treatment of effluents prior to discharge. Even traces of low-molecular-weight carbon compounds will result in slime development. Inadequate partial treatment may enhance slime growth by partially breaking down the effluent and releasing slime-promoting compounds. Intermittent discharge can reduce the standing crop of slime per unit surface area but as the total biomass supported by an effluent will remain the same, the slime will be extended over a greater length of river. Bacterial slimes are assemblages of filamentous and dispersed bacteria, and are far more common than fungal or algal dominated slimes. The two slime-forming organisms S. natans and zoogloeal bacteria are the major components of the majority of heterotrophic slimes, therefore any attempt at control should be aimed at these two species.     

主养鲢鳙非鲫高产鱼塘的初级生产力与能量转化效率的研究

分析测定了主养鲢鳙非鲫高产池塘浮游植物初级生产力的垂直、周日、周年变化及其与主要生态因素、鱼产量水平的关系。探讨了初级生产力在能量转化中的生态学效率:毛初级生产力对太阳辐射能的利用率为0.84％—1.64％;鲢鳙非鲫净产量对浮游植物净产量的直接利用率为8.46％—15.56％;太阳能转化为成产量的生态学效率为0.058％—0.156％。     

主养青鱼高产池塘的初级生产力及其能量转化为鲢、鳙产量的效率

本文论述了主养青鱼高产池塘浮游植物初级生产力的测定结果,揭示了其垂直、季节变化及其与主要生态因子、鱼产量水平、鲢、鳙鱼产量的关系,分析了D/B、P_G/R_W、N/P的作用。研究查明:1米以上水柱的光合产氧量占水柱总产氧量的90％以上。水柱日毛产氧量变动在5.00—17.04克氧/平方米·日之间,水柱年产氧量达2063—2814克氧/平方米·年。初级生产量全年只有一个高峰,常出现在7—8月。主养青鱼型年净产鱼量7500、11250、15000公斤/公顷级池塘的浮游植物鲜重净产量分别为100 674.4、118 560、128 197.6公斤/公顷·年,青鱼、草鱼并重型年净产鱼量15000公斤/公顷级池塘的浮游植物鲜重净产量为137 323.2公斤/公顷·年。 4—11月,毛初级生产力对太阳辐射能的利用率为0.81—1.11％;鲢、鳙产量对浮游植物净产量的直接利用率为3.49—5.13％;太阳能转移为鱼产量的生态学效率为0.028—0.055％。     

INFECTIVE ORGANISMS IN THE CYTOPLASM OF AMOEBA PROTEUS

Evidence from electron and phase microscopy is given which shows that infective organisms are present in the cytoplasm of Amoeba proteus. Vesicles containing living organisms have been observed after repeated washing and starvation of the amebae for a period of 2 weeks. Exposure to γ-radiation in conjunction with starvation, repeated washing, isolation of single amebae, refeeding with contaminant-free Tetrahymena, and clone selection has produced clones with reduced cytoplasmic infection. These findings are discussed in regard to the autoradiographic studies of other investigators on Amoeba proteus. The controversies over whether DNA and RNA are synthesized in the cytoplasm may be resolved by the finding of cytoplasmic infection.     

活性污泥中好气性异养细菌的初步研究

用活性污泥处理工业废水和生活污水是目前应用很广泛的一种生物处理法。此法近年来在我国已逐渐推广应用和发展,但对在处理过程中起主导作用的细菌却缺乏系统的研究。我们于1972年5月到12月对武汉印染厂废水处理场活性污泥中的微生物进行了一些观察,初步研究了好气性异养细菌的优势种类和数量,进行了一些菌株去除有机物能力的试验,希望通过这项工作取得生物处理中细菌学的资料,为进一步研究生物处理的原理和解决生产实践问题提供理论基础。       

HETEROTROPHIC UTILIZATION OF ACETATE AND GLUCOSE IN SWARTVLEI,SOUTH AFRICA

SUMMARY

The utilization of dissolved organic compounds in Swartvlei was measured by the addition of single concentrations of ¹⁴C-labelled acetate and glucose to water samples, The results indicated acetate uptake was greatest in the aerobic zone while glucose was predominantly utilized in the anaerobic zone. With the exception of two months, integral glucose uptake was usually greater than the uptake of acetate. In August and September 1971 acetate was indicated as being utilized predominantly by flagellates and in December 1971 by dinoflagellates. During the remainder of the study, bacteria were assumed to be responsible for the uptake of acetate. The extensive weed beds which surround the upper reaches of Swartvlei may be a major source of acetate and glucose in the pelagic water column.     

SODIUM CHLORIDE AND SELECTIVE DIFFUSION IN LIVING ORGANISMS

1. It is shown that NaCl acts like CaCl₂ or LaCl₃ in preventing the diffusion of strong acids through the membrane of the egg of Fundulus with this difference only that a M/8 solution of NaCl acts like a M/1,000 solution of CaCl₂ and like a M/30,000 solution of LaCl₃. 2. It is shown that these salts inhibit the diffusion of non-dissociated weak acid through the membrane of the Fundulus egg but slightly if at all. 3. Both NaCl and CaCl₂ accelerate the diffusion of dissociated strong alkali through the egg membrane of Fundulus and CaCl₂ is more efficient in this respect than NaCl. 4. It is shown that in moderate concentrations NaCl accelerates the rate of diffusion of KCl through the membrane of the egg of Fundulus while CaCl₂ does not.     

狗胃内幽门螺杆菌相关菌的调查研究

本实验对２５只成年狗和１２只幼犬,通过胃镜下活检或处死后立即取胃及十二指肠球部的六个部位的粘膜标本作尿素酶试验、涂片革兰氏染色、细菌培养和组织学检查。结果显示：（１）全部成年狗均有尿素酶试验阳性、革兰氏染色阴性的人胃螺旋菌相似菌定植,而无Ｈｐ相似菌定植。（２）该螺旋菌定植于胃小凹、腺管、和腺腔的底部,且在壁细胞内常可见到螺旋菌,少数出现壁细胞破坏。（３）粘膜有弥漫性慢性胃炎改变,胃底腺壁细胞数量减少。（４）经隔离的幼犬,在生后第６０天胃粘膜均见螺旋菌定植,以胃窦多见。结果表明：（１）狗胃中的螺旋菌具有一定致病性,可破坏壁细胞。（２）狗可能是人胃螺旋菌的传染源,而不是Ｈｐ的传染源。（３）不宜选用成年狗或较大的幼犬建立Ｈｐ感染普通狗模型,所选幼犬也需隔离。     

光合抑制剂DCMU对异养生长蓝藻叶绿素合成的作用

与被子植物不同,蓝藻叶绿素的合成存在依赖于光和不依赖于光的两条途径1,故异养生长的蓝藻在黑暗条件下同样合成叶绿素。在不同营养条件下,蓝藻的叶绿素合成也相对稳定,其含量常作为生物量的指标。已知DCMU是一种光合作用抑制剂,阻断光系统向质体醌的电子传递。有报道显示,DCMU可调控蓝藻Calothrix的细胞分化2。但DCMU对于蓝藻叶绿素合成的作用从未见报道。在对表达glk和lac ZYA基因蓝藻的异养生长研究中3,作者发现DCMU显著抑制丝状固氮蓝藻的叶绿素合成,而对单细胞蓝藻没有影响。       

猪胃螺杆样细菌与幽门螺杆菌的比较研究

我们检测１０例普通猪的胄组织,有８例分离到螺杆菌样细菌（ＨＬＯ）。其菌落、菌体形态和某些生化反应与幽门螺杆菌（ＨＰ）相似,但其尿素酶活性较低,ＨＬＯ全菌蛋白的ＳＤＳ一ｐＡＧＥ图谱也与ＨＰ的不同。本文就ＨＰ和ＨＬＯ及其伴发的人、猪慢性胃炎的特点,作了比较和讨论。