饥饿及再投喂对日本囊对虾糖代谢的影响

研究了日本囊对虾在饥饿和再投喂下血糖、肝胰脏糖原和肌糖原含量的变化.结果表明：在饥饿状态下,日本囊对虾肝胰脏糖原含量和血糖浓度在饥饿开始时迅速下降,肌糖原含量在饥饿10 d时下降到最低值,在饥饿10~15 d时通过糖原异生作用又恢复至最初水平,但随着饥饿时间的延长,糖原含量持续下降.恢复投喂后,肝胰脏糖原含量和肌糖原含量均能得到较好恢复,饥饿10 d和 15 d组的血糖浓度在恢复投喂10 d后显著高于对照组,但饥饿25 d组的血糖浓度始终显著低于对照.表明饥饿时间过长,对血糖浓度的恢复有较大影响     

高效降解石油外生菌根真菌的室内筛选

对7个外生菌根真菌菌株在不同石油浓度培养基中的生长及其对石油的降解作用进行了研究。结果表明:(1)不同菌株在同一石油浓度培养基中生长速度不同,同一菌株在不同石油浓度培养基中的生长速度亦不同。菌株010和菌株025在不同石油浓度培养基中生长速度均较其他菌株快。菌株010的菌丝干重随着石油浓度的增加而增加,当石油质量浓度为500 mg/L时,菌丝干重达到最大值,高于对照5.27%,石油对其生长产生了促进作用;当石油质量浓度为700 mg/L时,菌丝干重低于对照,随着石油质量浓度的升高,菌株生长呈下降趋势。石油质量浓度为100 mg/L时,菌株025生长最慢,菌丝干重低于对照9.1%。随着石油浓度的增加,菌株生长加快,当石油质量浓度为500 mg/L时,菌丝干重高于对照;当石油质量浓度为700 mg/L时,菌株025菌丝干重最高,高于对照25.65%。随着石油浓度的再度升高,菌株生长呈下降趋势。(2)不同菌株在同一石油浓度下对石油的降解能力不同,同一菌株在不同石油浓度下对石油的降解能力亦不同。菌株025对石油的降解能力最强,对石油的降解能力随着石油浓度的升高而提高。当培养基中石油质量浓度为900 mg/L时,菌株025对石油的降解率最高,达到73.65%。(3)菌株0100、09、035、LH004的菌丝生物量与对石油的降解能力呈正相关。     

Continuous monitoring of lactate during exercise in humans using subcutaneous and transcutaneous microdialysis

We have evaluated the possibility of monitoring the plasma lactate concentration in human volunteers during cycle ergometer exercise using subcutaneous and transcutaneous microdialysis. In transcutaneous microdialysis, the relative increase in dialysate lactate concentration exceeded that of plasma lactate concentration by a factor of 6 during exercise due to exercise-induced lactate secretion in sweat. During exercise the subcutaneous microdialysis dialysate lactate concentration underestimated the plasma lactate concentration possibly due to diffusion limitation or adipose tissue lactate production. While it was demonstrated that microdialysis can be used for on-line lactate monitoring, neither subcutaneous nor transcutaneous dialysate lactate concentration were linearly related to the plasma lactate concentration during exercise, and it was found therefore that it was not possible to monitor directly plasma lactate concentration during exercise.     

The relation between cell size, ploidy level and nitrate concentration in lettuce

In two experiments the relation between cell size, ploidy level and nitrate concentration of genotypes of lettuce ( Lactuca saliva L.) was investigated. Artificial increase of cell size by application of gibberellic acid to young plants decreased the percentage dry weight and the concentration of organic acids in the plant sap and increased the nitrate concentration of the shoot. Application of chlormequat chloride caused the opposite effects. Tetraploid genotypes of lettuce had larger cells, a lower nitrate concentration and a higher concentration of organic solutes than diploid genotypes. Genotypical differences in nitrate concentration could not be explained by differences in cell size, but were consistently related to differences in concentration of organic acids in plant sap. The percentage dry weight of genotypes was positively correlated with the concentration of organic acids in plant sap. However, differences in nitrate concentration were also found among genotypes with comparable dry matter content. These differences could be caused by differences in partitioning of photosynthates over structural components and organic acids in the vacuoles. Mono-saccharides seem to be less important than organic acids for explaining genotypical differences in nitrate level, because the concentration of monosaccharides was much lower than that of organic acids and because a negative relation between the concentration of monosaccharides and of nitrate was not found in every case. Genotypical differences in nitrate accumulation were not related to differences in osmolarity.     

狭窄血管远心端低密度脂蛋白浓度极化促进动脉粥样硬化形成

低密度脂蛋白（low density lipoprotein,LDL）浓度极化可能是动脉粥样硬化局灶性的重要原因,本文以狭窄血管远心端为研究对象,探讨LDL浓度极化对动脉粥样硬化发生、发展的影响。用数值计算模拟狭窄血管远心端LDL的壁面浓度分布,用激光扫描共聚焦显微镜测定狭窄血管远心端LDL沿z轴的浓度分布;用外科手术方法建立颈总动脉局部狭窄的实验模型,从整体动物水平观察LDL浓度极化对动脉粥样硬化形成的影响。数值计算和激光扫描共聚焦显微镜测定的结果表明,狭窄血管远心端存在显著的LDL浓度极化现象,且LDL壁面浓度与入口液流速度和狭窄程度有关：在相同的速率下,LDL壁面浓度在狭窄度为40％的圆管内最大;在狭窄程度相同的情况下,雷诺数（Re）为250时测得的LDL壁面浓度高于Re为500时测得的壁面浓度。整体动物实验表明,在狭窄血管远心端LDL浓度极化显著的区域形成明显的动脉粥样硬化病变,并且有大量的脂质沉积。以上结果提示,LDL浓度极化可能是导致动脉粥样硬化局灶性的重要因素。     

Eggshell biliverdin concentration does not sufficiently predict eggshell coloration

Avian eggshell coloration may have arisen due to selection on the biological, chemical, or physical properties of the pigments embedded within the eggshell, or due to selection on the coloration that emerges due to pigment deposition. Within both hypothetical frameworks, pigment‐based eggshell coloration would be related to metrics of egg quality; however, no one has evaluated the relative strength of coloration and pigment concentration in predicting egg quality. Here, we examined 66 European starling Sturnus vulgaris eggs and quantified eggshell biliverdin concentration (an antioxidant that produces the eggshell's blue coloration) and used 28 different coloration metrics derived from both photographic and spectrophotometric data. We also measured egg size, eggshell thickness, concentration of carotenoids in the yolk, and concentration of lysozyme in the albumen to capture variation in egg quality. We found that throughout the laying sequence, biliverdin concentration increased while eggshell thickness, yolk carotenoid concentration, and lysozyme concentration in the albumen all decreased, but this variation was not captured by any eggshell coloration metric. Both eggshell coloration and biliverdin concentration were negatively associated with yolk carotenoid concentration, but only eggshell biliverdin concentration was negatively associated with yolk mass. Lastly, biliverdin concentration explained, at most, only 46% of the variation for all eggshell coloration metrics. Our results suggest biliverdin concentration is a better predictor of egg quality than egg coloration in European starlings, supporting the hypothesis that eggshell pigment concentration per se may be the target of selection.     

Relation of blood composition to age in the larval female house cricket, Acheta domesticus

The blood volume, osmolality, and sugar concentration increase; the blood protein and lipid concentration decrease; and the blood ions and NPS concentration do not change during apolysis from the 7th to 8th instar of larval Acheta domesticus. The patterns of change in all blood constituents are basically identical in both of the last two larval instars. Blood volume increase is directly related to growth, but not directly to total body water. Blood protein concentration increases in exact relation to growth, resulting in a doubling of concentration by midinstar and a small decrease over the last 2 to 3 days. The concentration of clottable protein remains constant; the soluble protein concentration increase probably providing cuticular proteins prior to and following ecdysis. Blood lipid concentration increases steadily throughout both instars, even during the non-feeding phase. Total blood carbohydrate concentration decreases greatly in the first 2 days of an instar, then remains relatively constant for the remainder of the instar. Blood trehalose concentration is 85% of the total carbohydrate concentration throughout the instar, but drops to 65% with a corresponding increase in ‘other sugars’ with the onset of apolysis on the last day. Growth demands probably exceed dietary supply of amino acids resulting in a 50% decrease in NPS concentration in the first half of the instar, then NPS concentration increases in spite of a declining feeding rate because growth demands cease. Within the normal blood ion lability range, the principle blood ions, sodium and chloride, vary in an inverse proportion to NPS and sugar concentration at least in the first two-thirds of the instar. Thus blood osmolality is constant except for an unexplained drop in the last 2 days of an instar.     

Fluorometric determination of the DNA concentration in municipal drinking water

DNA concentrations in municipal drinking water samples were measured by fluorometry, using Hoechst 33258 fluorochrome. The concentration, extraction, and detection methods used were adapted from existing techniques. The method is reproducible, fast, accurate, and simple. The amounts of DNA per cell for five different bacterial isolates obtained from drinking water samples were determined by measuring DNA concentration and total cell concentration (acridine orange epifluorescence direct cell counting) in stationary pure cultures. The relationship between DNA concentration and epifluorescence total direct cell concentration in 11 different drinking water samples was linear and positive; the amounts of DNA per cell in these samples did not differ significantly from the amounts in pure culture isolates. We found significant linear correlations between DNA concentration and colony-forming unit concentration, as well as between epifluorescence direct cell counts and colony-forming unit concentration. DNA concentration measurements of municipal drinking water samples appear to monitor changes in bacteriological quality at least as well as total heterotrophic plate counting and epifluorescence direct cell counting.     

Fluorometric determination of the DNA concentration in municipal drinking water.

DNA concentrations in municipal drinking water samples were measured by fluorometry, using Hoechst 33258 fluorochrome. The concentration, extraction, and detection methods used were adapted from existing techniques. The method is reproducible, fast, accurate, and simple. The amounts of DNA per cell for five different bacterial isolates obtained from drinking water samples were determined by measuring DNA concentration and total cell concentration (acridine orange epifluorescence direct cell counting) in stationary pure cultures. The relationship between DNA concentration and epifluorescence total direct cell concentration in 11 different drinking water samples was linear and positive; the amounts of DNA per cell in these samples did not differ significantly from the amounts in pure culture isolates. We found significant linear correlations between DNA concentration and colony-forming unit concentration, as well as between epifluorescence direct cell counts and colony-forming unit concentration. DNA concentration measurements of municipal drinking water samples appear to monitor changes in bacteriological quality at least as well as total heterotrophic plate counting and epifluorescence direct cell counting.     

Intracellular ion concentrations in the frog cornea epithelium during stimulation and inhibition of Cl secretion

Summary The intracellular electrolyte concentrations in the isolated cornea of the American bullfrog were determined in thin freeze-dried cryosections using energy-dispersive X-ray microanalysis. Stimulation of Cl secretion by isoproterenol resulted in a significant increase in the intracellular Na concentration but did not change the intracellular Cl concentration. Similar results were obtained when Cl secretion was stimulated by the Ca ionophore A23187. Inhibition of Cl secretion by ouabain produced a large increase in the intracellular Na concentration and an equivalent fall in the K concentration. Again, no increase or decrease in the intracellular Cl concentration was detectable. Clamping of the transepithelial potential to ±50 mV resulted in parallel changes in the transepithelial current and intracellular Na concentration, but, with the exception of the outermost cell layer, in no changes of the Cl concentration. Only when Cl secretion was inhibited by bumetanide or furosemide, together with a decrease in the Na concentration, was a large fall in the Cl concentration observed. Application of loop diuretics also produced significant increases in the P concentration and dry weight, consistent with some shrinkage of the epithelial cells. The results suggest the existence of a potent regulatory mechanism which maintains a constant intracellular Cl concentration and, thereby, a constant epithelial cell volume. Through the operation of this system any variation in the apical Cl efflux is compensated for by an equal change in the rate of Cl uptake across the basolateral membrane. Cl uptake is sensitive to loop diuretics, directly coupled to an uptake of Na, and dependent on the Na and K concentration gradients across the basolateral membrane. Isoproterenol and A23187 seem to increase the Cl permeability of the apical membrane and thus stimulate Cl efflux. Ouabain inhibits Cl secretion by abolishing the driving Na concentration gradient for Cl uptake across the basolateral membrane.     

Free amino acids in the spinal cord and ganglia of dogs after ligation of the abdominal aorta

The authors studied the effect of 40 min and 6 days occlusion of the abdominal aorta on the aspartate [Asp], glutamic acid [Glu], glutamine [Gln], glycine [Gly] and alanine [Ala] concentration in both parts of the grey matter of the lumbosacral cord, in the spinal ganglia and along the dorsal fasciculi. After 40 min ischaemia, an increase was found in the Glu, Gln, Gly and Ala concentration in the dorsal part of the grey matter and in the Glu, Gly and Ala concentration in the spinal ganglia. In the ventral part of the grey matter only the Ala concentration was increased. After 6-day ligation, the Asp and Gly concentration fell in the ventral horns, while the Gly concentration rose in the dorsal horns. The Ala and Asp concentration in the spinal ganglia rose. After this interval the Asp and Glu concentration also rose in the fasciculus gracilis. The Ala/Glu concentration ratio showed the most pronounced increase in the central horns of the grey matter.     

Zinc concentration in erythrocyte membranes in normal volunteers and in patients with taste and smell dysfunction

Erythrocyte membrane zinc concentration was measured in 14 normal volunteers and in 36 patients with taste and smell dysfunction, and compared with zinc concentration in erythrocyte cytosol and blood plasma in the normal volunteers and with zinc concentration in erythrocyte cytosol, blood serum, urine, and parotid saliva in the patients. A A significant negative correlation was found between age and membrane zinc concentration in the normals. A significant positive correlation was found between parotid saliva zinc and erythrocyte membrane zinc concentrations in the patients. Concentration of zinc in the erythrocyte membrane is 50% greater than its concentration in cytosol, and three times greater than the zinc concentration in plasma or serum; membrane zinc concentration in humans is approximately one-half that reported in the dog or in the mouse.     

2012—2016年海淀区气传花粉物候特征及其与气象要素的关系

利用重力沉淀法对2012—2016年海淀区气传花粉种类及含量进行监测,分析海淀区的花粉种类、峰值分布特征和含量变化、以及花粉浓度的不连续变化特征,在此基础上采用集合经验模态分解法对花粉浓度进行多时间尺度分析,并分析了花粉浓度与气象要素之间的关系.结果表明: 研究期间,海淀区的主要气传花粉种类已经发生改变,柏科、杨柳科等木本植物代替草本植物成为含量最多的气传花粉类别;花粉浓度的年内峰值分布并无明显改变;近5年花粉浓度整体呈下降趋势,但橘科等草本植物花粉浓度呈上升趋势;统计时段内,花粉浓度在4月上旬、5月下旬及8月上旬共发生3次不连续变化;花粉浓度存在准2 d、准51 d、准128 d的变化周期;温度对于花粉浓度的影响在各气象要素中占有主导地位,16～18 ℃范围内花粉浓度明显升高;气温的变化对逐日花粉浓度的影响具有一定的滞后性和持续性,通常与滞后2～7 d的花粉浓度相关性较高,日照时数和风速对当天的花粉浓度影响最显著.     

Quantitating the concentration of Py-Im polyamide-fluorescein conjugates in live cells

Quantitative fluorescence-based methods have been developed to determine the nuclear concentration of polyamide-fluorescein conjugates in cell culture. Confocal laser scanning microscopy and flow cytometry techniques are utilized to plot calibration curves, from which the nuclear concentration can be interpolated. Upon treatment with polyamide, the concentration in the nucleus of live HeLa cells is calculated to be between 0.1 and 0.5microM, which is significantly lower than the 2microM dosage concentration. In contrast, the observed nuclear concentration in U251 cells is closer to the dosage concentration, indicating a cell line-specific increase in uptake for this class of compounds. Although confocal microscopy and flow cytometry generate disparate values, taken together these experiments suggest that the polyamide concentration inside the cell nucleus is lower than it is outside the cell.     

Interpreting the carboxyhaemoglobin concentration in fetal cord blood

We calculated the fetal-to-maternal carboxyhaemoglobin concentration ratio in 19 mother-infant pairs at the time of term delivery. Mothers, who had a less than 10% drop in their carboxyhaemoglobin concentration during labour, had an average ratio of 1.40 +/- 0.19. For mothers whose carboxyhaemoglobin concentrations dropped by 10% or more during labour, the average fetal-to-maternal carboxyhaemoglobin concentration ratio was 1.83 +/- 0.48. There was a strong correlation (r = 0.82) between the percent change in maternal carboxyhaemoglobin concentration during labour and the fetal-to-maternal carboxyhaemoglobin concentration ratio at the time of delivery. We conclude that increased CO elimination during labour may be accompanied by rapid changes in the maternal carboxyhaemoglobin concentration, leading to a spuriously high fetal-to-maternal carboxyhemoglobin concentration ratio at the time of delivery.     

A possible role for guanosine 3′,5′-monophosphate in the stimulus-secretion coupling in exocrine pancreas

Carbamylcholine, caerulein and cholecystokinin octapeptide rapidly increased the cyclic GMP concentration and amylase secretion in isolated guinea pig pancreatic slices. The cyclic GMP concentration was increased eight-fold over the basal concentration in 30 s, with concomitant increase in the rate of amylase secretion. The tissue concentration of cyclic GMP then rapidly declined to a plateau value of approx. 16% of the peak level within 10 min and was maintained at that concentration for the duration of the experiment. We have shown earlier (Kapoor, C.L. and Krishna, G. (1977) Science 196, 1003–1005) that the decrease of tissue cyclic GMP was due mainly to the secretion of cyclic GMP into the medium. The cyclic AMP concentration in the tissue was not changed, nor was it secreted into the medium.There was a correlation between the concentration response to various agents for the increase in cyclic GMP concentration and amylase secretion in pancreatic slices. Carbamylcholine increased both the cyclic GMP concentration and amylase secretion; the half-maximal effect was achieved at 1.5 μM concentration. Caerulein and cholecystokinin octapeptide were 5000 times more potent than carbamylcholine in increasing cyclic GMP concentration and amylase secretion; the half-maximal effect was achieved at 0.3 nM concentration. Atropine, which completely inhibited the increase in cyclic GMP and amylase secretion induced by carbamylcholine, did not block the effects of caerulein or cholecystokinin octapeptide. These results suggest that various secretagogues induced amylase secretion by increasing the cyclic GMP concentration, but the mechanism by which cyclic GMP caused amylase secretion remains to be elucidated.     

A possible role for guanosine 3',5'-monophosphate in the stimulus-secretion coupling in exocrine pancreas.

Carbamylcholine, caerulein and cholecystokinin octapeptide rapidly increased the cyclic GMP concentration and amylase secretion in isolated guinea pig pancreatic slices. The cyclic GMP concentration was increased eight-fold over the basal concentration in 30 s, with concomitant increase in the rate of amylase secretion. The tissue concentration of cyclic GMP then rapidly declined to a plateau value of approx. 16% of the peak level within 10 min and was maintained at that concentration for the duration of the experiment. We have shown earlier (Kapoor, CL. and Krishna, G. (1977) Science 196, 1003--1005) that the decrease of tissue cyclic GMP was due mainly to the secretion of cyclic GMP into the medium. The cyclic AMP concentration in the tissue was not changed, nor was it secreted into the medium. There was a correlation between the concentration response to various agents for the increase in cyclic GMP concentration and amylase secretion in pancreatic slices. Carbamylcholine increased both the cyclic GMP concentration and amylase secretion; the half-maximal effect was achieved at 1.5 micrometer concentration. Caerulein and cholecystokinin octapeptide were 5000 times more potent than carbamylcholine in increasing cyclic GMP concentration and amylase secretion; the half-maximal effect was achieved at 0.3 nM concentration. Atropine, which completely inhibited the increase in cyclic GMP and amylase secretion induced by carbamylcholine, did not block the effects of caerulein or cholecystokinin octapeptide. These results suggest that various secretagogues induced amylase secretion by increasing the cyclic GMP concentration, but the mechanism by which cyclic GMP caused amylase secretion remains to be elucidated.     

Active concentration measurements of recombinant biomolecules using biosensor technology

Whereas the concentration of a biomolecule simply refers to the amount of chemical substance per unit of volume, its active concentration refers to a relational parameter that has meaning only with respect to the molecule's ability to interact specifically with one particular ligand. When proteins are studied in a biological context, it is the biologically active concentration that is relevant, and not the total concentration of correctly and incorrectly folded molecules. Using a biosensor instrument the concentration of active biomolecules in a preparation can be measured by injecting the preparation at different flow rates onto a sensor chip surface presenting a high concentration of a specific ligand. The method can be used under conditions of partial mass transport limitation and does not require a pre-established standard curve. When the method was used to measure the active concentration of several recombinant proteins it was found that the active concentration was much lower than the nominal concentration determined by conventional methods. The active concentration also depended on the ligand used in the binding assay, reflecting the fact that active concentration can only be defined with respect to one specific probe. Such discrepancies in concentration values, if undetected, may lead to erroneous conclusions regarding the properties and behaviour of recombinant proteins tested in different assays.     

圆红冬孢酵母利用生物乙醇废水-木薯粉水解液发酵产油

【目的】获得能够高效降解生物乙醇废水化学需氧量(COD)的圆红冬孢酵母菌株,评估废水初始COD浓度对驯化菌株生长的影响,将木薯粉生产微生物油脂和高浓度有机废水降解过程整合,以生物乙醇废水为水源制备生物乙醇废水-木薯粉水解液培养基,明确产油效率高、生物乙醇废水COD降解率高的初始还原糖浓度。【方法】采用在高浓度的生物乙醇废水中进行多次驯化的方法,获得能够适应废水环境的圆红冬孢酵母菌株;采用双酶水解法对加入乙醇废水中的木薯粉进行水解;采用重量法监测生物量浓度变化,采用酸热法提取油脂,重铬酸钾法监测COD,DNS法测定废水还原糖浓度,凯氏定氮法测定总氮,钼酸铵比色法测定总磷。【结果】通过驯化筛选得到一株能耐受高浓度生物乙醇废水的优势菌株Rhodosporidium toruloides D5。以未稀释的废水为培养基,驯化菌株的最终生物量浓度和COD降解率分别为3.8 g/L和75.0%。采用生物乙醇废水-木薯粉水解液发酵时,控制初始还原糖浓度低于30 g/L时,生物量浓度和油脂浓度随初始还原糖浓度的升高而升高,均在120 h时达到最高COD降解率,初始还原糖浓度对达到的最大COD降解率无明显影响,废水N、P去除率分别达到99%和92%以上。【结论】在未经稀释的高浓度生物乙醇废水中可获得较高的生物量浓度;采用高浓度生物乙醇废水-木薯粉水解液培养基发酵产油,初始还原糖浓度为30 g/L,可在保证高油脂产量的同时,实现废水COD的高效降解,有效回收利用废水中残余的N、P源,从而降低微生物油脂生产和废水处理成本,研究结果可为开发廉价微生物油脂生产技术提供有用的参考。     

Copper concentration in plants and in the rhizosphere as influenced by the iron status of tomato (Lycopersicon esculentum L.)

Changes of metal concentration that occur in the rhizosphere may arise from several processes including variation in the concentration of complexing ligands, pH or redox potential that can be influenced by the Fe status of the plant. The aim of this study was to assess for both acidic and calcareous, Cu-contaminated soils how Cu concentration in plants and in the rhizosphere was affected by the Fe status of a strategy I plant species. The change of soil solution pH, total solution Cu concentration and soil redox potential was monitored for 8 days in the rhizosphere of tomato (Lycopersicon esculentum L.) in response to contrasting Fe supply. The concentration of Cu in roots was enhanced under Fe deficiency in the acidic soils. Shoot Cu however did not vary with the Fe status of the plant. The plant Fe status had little effect on rhizosphere pH, redox potential or Cu concentration in solution in either acidic or calcareous soils. Marked differences in pH and solution Cu concentration were observed between rhizosphere and uncropped soils. Roots induced an increase in pH of acidic soils and a decrease in solution Cu concentration in all soils. The decrease in solution Cu concentration in acidic soils may be explained by the increase in rhizosphere pH. The proposed device provided new data on the fate of Cu in the rhizosphere and showed a positive correlation for the four soils considered together between the total Cu concentration in soil solution and root Cu concentration.