STUDIES ON LUMINOUS BACTERIA : II. THE INFLUENCE OF TEMPERATURE ON THE INTENSITY OF THE LIGHT OF LUMINOUS BACTERIA.

1. A method has been described whereby the intensity of the light of luminous bacteria may be measured in a quantitative manner. 2. It is pointed out that the temperature coefficients for light intensity do not follow the van''t Hoff rule, but are higher and vary with each 10° temperature interval. 3. From a comparison with other data it is found that the process is not a simple one, but that the observed curve is the resultant of several reactions which proceed simultaneously. 4. The discrepancies in the temperature coefficients in the neighborhood of the "optimum temperature" may be due to a process of coagulation of the colloidal particles of the enzyme. This coagulation will tend to cause a deviation of the curve away from that normal for chemical reactions.     

THE TOTAL LUMINOUS EFFICIENCY OF LUMINOUS BACTERIA

Methods are described for measuring the light emitted by an emulsion of luminous bacteria of given thickness, and calculating the light emitted by a single bacterium, measuring 1.1 x 2.2 micra, provided there is no absorption of light in the emulsion. At the same time, the oxygen consumed by a single bacterium was measured by recording the time for the bacteria to use up .9 of the oxygen dissolved in sea water from air (20 per cent oxygen). The luminescence intensity does not diminish until the oxygen concentration falls below 2 per cent, when the luminescence diminishes rapidly. Above 2 per cent oxygen (when the oxygen dissolving in sea water from pure oxygen at 760 mm. Hg pressure = 100 per cent) the bacteria use equal amounts of oxygen in equal times, while below 2 per cent oxygen it seems very likely that rate of oxygen absorption is proportional to oxygen concentration. By measuring the time for a tube of luminous bacteria of known concentration saturated with air (20 per cent oxygen) to begin to darken (2 per cent oxygen) we can calculate the oxygen absorbed by one bacterium per second. The bacteria per cc. are counted on a blood counting slide or by a centrifugal method, after measuring the volume of a single bacterium (1.695 x 10^–12 cc.). Both methods gave results in good agreement with each other. The maximum value for the light from a single bacterium was 24 x 10^–14 lumens or 1.9 x 10^–14 candles. The maximum value for lumen-seconds per mg. of oxygen absorbed was 14. The average value for lumen-seconds per mg. O₂ was 9.25. The maximum values were selected in calculating the efficiency of light production, since some of the bacteria counted may not be producing light, although they may still be using oxygen. The "diet" of the bacteria was 60 per cent glycerol and 40 per cent peptone. To oxidize this mixture each mg. of oxygen would yield 3.38 gm. calories or 14.1 watts per second. 1 lumen per watt is therefore produced by a normal bacterium which emits 14 lumen-seconds per mg. O₂ absorbed. Since the maximum lumens per watt are 640, representing 100 per cent efficiency, the total luminous efficiency if .00156. As some of the oxygen is used in respiratory oxidation which may have nothing to do with luminescence, the luminescence efficiency must be higher than 1 lumen per watt. Experiments with KCN show that this substance may reduce the oxygen consumption to 1/20 of its former value while reducing the luminescence intensity only ¼. A partial separation of respiratory from luminescence oxidations is therefore effected by KCN, and our efficiency becomes 5 lumens per watt, or .0078. This is an over-all efficiency, based on the energy value of the "fuel" of the bacteria, regarded as a power plant for producing light. It compares very favorably with the 1.6 lumens per watt of a tungsten vacuum lamp or the 3.9 lumens per watt of a tungsten nitrogen lamp, if we correct the usual values for these illuminants, based on watts at the lamp terminals, for a 20 per cent efficiency of the power plant converting the energy of coal fuel into electric current. The specific luminous emission of the bacteria is 3.14 x 10^–6 lumens per cm². One bacterium absorbs 215,000 molecules of oxygen per second and emits 1,280 quanta of light at λ_max = 510µµ. If we suppose that a molecule of oxygen uniting with luminous material gives rise to the emission of 1 quantum of light energy, only 1/168 of the oxygen absorbed is used in luminescence. On this basis the efficiency becomes 168 lumens per watt or 26.2 per cent.     

THE OXYGEN CONSUMPTION OF LUMINOUS BACTERIA

Oxygen consumption of luminous bacteria determined by the Thunberg micro respirometer and by the time which elapses before the luminescence of an emulsion of luminous bacteria in sea water begins to dim, when over 99 per cent of the dissolved oxygen has been consumed, agree exactly. Average values for oxygen consumption at an average temperature of 21.5°C. are 4.26 x 10^–11 mg. O₂ per bacterium; 2.5 x 10⁴ mg. per kilo and 5.6 mg. O₂ per sq. m. of bacterial surface. The only correct comparison of the oxygen consumption of different organisms or tissues is in terms of oxygen used per unit weight with a sufficient oxygen tension so that oxygen consumption is independent of oxygen tension. Measurement of the oxygen concentration which just allows full luminescence, compared with a calculation of the oxygen concentration at the surface of a bacterial cell just necessary to allow the observed respiration throughout all parts of the cell, indicates that oxygen must diffuse into the bacterium much more slowly than through gelatin or connective tissue but not as slowly as through chitin.     

THE EFFECTS OF LIGHT ON LUMINOUS BACTERIA

A conservative statement would therefore be that luminous bacteria show no changes in luminescence as a result of illumination by 625 foot candles for 1.5 minutes when examined 1/200 of a second after exposure, and none as the result of illumination by 15,000 foot candles for 6 minutes when examined ⅙ of a second after exposure.     

THE MINIMUM CONCENTRATION OF OXYGEN FOR LUMINESCENCE BY LUMINOUS BACTERIA

A method is described for measuring the concentration of oxygen to allow just perceptible luminescence of luminous bacteria. The value turns out to be extraordinarily low, about 0.005 mm. Hg pressure O₂ or 1 part by weight oxygen dissolved in 3,700,000,000 cc. sea water.     

硫酸盐还原菌耐药性研究

硫酸盐还原菌（简称SRB）对杀菌剂十二烷基二甲基等基氯化铵（简称“1227”）的耐药性是由药物诱导产生,这种由适应所产生的耐药性获得快而且是可逆的,随着时间的推迟抗药性减弱,6个月后抗药性逐渐消失。研究还表明SRB对甲硝叹没有明显的交叉耐药性。     

THE RESPIRATION OF LUMINOUS BACTERIA AND THE EFFECT OF OXYGEN TENSION UPON OXYGEN CONSUMPTION

1. The respiration of luminous bacteria has been studied by colorimetric and manometric methods. 2. Limulus oxyhaemocyanin has been used as a colorimetric indicator of oxygen consumption and indicator dyes were used for colorimetric determination of carbon dioxide production. 3. The Thunberg-Winterstein microrespirometer has been used for the measurement of the rate of oxygen consumption by luminous bacteria at different partial pressures of oxygen. 4. The effect of oxygen concentration upon oxygen consumption has been followed from equilibrium with air to low pressures of oxygen. 5. Luminous bacteria consume oxygen and produce carbon dioxide independent of oxygen pressures from equilibrium with air (152 mm.) to approximately 22.80 mm. oxygen or 0.03 atmosphere. 6. Dimming of a suspension of luminous bacteria occurs when oxygen tension is lowered to approximately 2 mm. Hg (0.0026 atmosphere) and when the rate of respiration becomes diminished one-half. 7. Pure nitrogen stops respiratory activity and pure oxygen irreversibly inhibits oxygen consumption. 8. The curve for rate of oxygen consumption with oxygen concentration is similar to curves for adsorption of gasses at catalytic surfaces, and agrees with the Langmuir equation for the expression of the amount of gas adsorbed in unimolecular layer at catalytic surfaces with gas pressure. 9. A constant and maximum rate of oxygen consumption occurs in small cells when oxygen concentration becomes sufficient to entirely saturate the surface of the oxidative catalyst of the cell.     

A PRELIMINARY STUDY OF THE OKAVANGO LECHWE

• 1. Lechwe herds in the Okavango exist only where the flood plain is of sufficient breadth (over 100 m in the low-water season) and where open water is present. During the season of greatest breeding activity groups may show either territorial or non-territorial forms of social organization depending upon the size and degree of fragmentation of the flood plain area occupied.
• 2. Lechwe employ bounding and trotting gaits when frightened or fleeing predators. These gaits seem well suited for rapid movement through shallow water.
• 3. Male courtship behaviour includes the use of an outstretched neck posture, frequent inspection of the female anogenital area, performance of “Laufschlag” and “driving”. The Laufschlag is believed to be a ritualized act derived from the mounting motion. Receptive females display outstretched neck posture with head lowered, hunched body conformation, spreading of hindlegs and curling of tail to one side.
• 4. Most calves are born in the summer months soon after the high waters recede. Young calves are cached in tall riverine vegetation during the day and nursed in early morning and evening.
• 5. The daily activity cycle and other aspects of behaviour are described.

     

A STUDY OF THE EFFECT OF TANNINS ON THE GROWTH OF SULPHATE-REDUCING BACTERIA

SUMMARY: The inhibition by tannins of sulphate-reducing bacteria in pure culture has been shown to be due primarily to the establishment of an unfavourable pH. High concentrations were required to inhibit when the physico-chemical conditions were otherwise favourable.     

稀的Ju鲫的染色体核型初报

稀有鲫 (ＧｏｂｉｏｃｙｐｒｉｓｒａｒｕｓＹｅｅｔＦｕ)是我国特产的一种小型鲤科 (Ｃｙｐｒｉｎｉｄａｅ)鱼类 ,属于亚科(Ｄａｎｉｏｎｉｎａｅ)鲫属[1 ] 。稀有鲫具有适应力强、性成熟周期短、繁殖季节长、产卵频次多等特点 ,是一种有发展前途的实验动物 ,已经被越来越多地应用到生态、遗传、生理和环境毒理等研究领域。但是 ,有关稀有鲫的细胞学背景研究还不够充分 ,其染色体核型仅有个别非正式的研究报告。本文对稀有鲫的染色体核型以及核仁组织区的银染结果作了初步研究 ,现将结果报道如下。1　材料与方法稀有鲫由本所…     

天蛾科外生殖器的初步研究

本文描述了34种天蛾雌雄外生殖器主要部分的基本构造和变异类型。根据比较观察的结果,作者认为在各亚科之间,雄史的钩形突、抱器、抱器鳞和抱器桥等有所不同,而抱器腹突,阳茎端上的突起,交配囊以及交配囊体上的标记等在各个种间的差别亦相当显著,可做为鉴别的特征。     

中国肉疣衣属地衣的初步研究*

肉疣衣属地衣为世界广布属之一,该属为壳状地衣,地衣体通常龟裂具疣,子囊果盘状一般无柄贴生,盘缘明显,侧丝分枝结网状,孢子大型。本文对中国肉疣衣属地衣进行了初步研究,并报道了该属地衣共16种,其中中国新记录5种,即寒生肉疣衣、柱芽肉疣衣、粉末肉疣衣、亚裂芽肉疣衣、亚绿肉疣衣。     

黄嘴白鹭的繁殖生物学

The Chinese egret is a globally endangered species. This paper describes the breeding behavior of the Chinese egret (Egretta eulophotes) on Xingrentuo Islet, Changhai County, Liaoning Province between April and August 2001. 150 breeding pairs were found at this site, and 60 more pairs were found on nearby Yuanbaotuo Islet, the largest breeding colony in China. Chinese egret arrived at the islet from mid April and departed from late August. Their nests were built in the branches of low trees and fleabanes. 2～6 light greenish blue eggs were layed in each clutch. 40 eggs averaged 45 56(±2 05)mm×33 57(±0 74)mm in size,and 26 46±1 88)g in weight. The hatching period was 21～23 days.     

牛蛙（Rana catesbeiana）染色体高分辨带显示的初步探讨

本文报道显示牛蛙染色体高分辨带的一种方法。通过2—巯基乙醇的预处理和Ohnuki低渗液和低渗及火焰干燥可使染色体伸长并显出高分辨带纹,且这种带纹和人的高分辨G带类似。初步探讨了牛蛙染色体高分辨显带机理。