The energetics of starvation and growth after refeeding in juveniles of three cyprinid species

Synopsis Experiments were conducted to monitor changes in body mass and metabolic energy expenditure before, during, and after periods of starvation in juveniles of three species of cyprinids: Leuciscus cephalus, Chalcalburnus chalcoides mento, and Scardinius erythrophthalmus. During the starvation period all fish lost weight at about the same rate and the total amount of oxygen consumed during an experimental period of 20 h was about 40% lower in the starved than in the fed groups. Upon refeeding, both mass specific maintenance; and routine rates of metabolism as well as relative growth rates increased rapidly, the peaks of these increases being directly proportional to the length of the starvation period. Maximum compensatory growth was observed after four weeks of starvation in C. chalcoides and S. erythrophthalmus, with relative growth rates reaching 30% d^-1 during the first measuring interval after refeeding. The pattern of time-dependent compensatory growth displayed by these fish is similar to the responses of a colonial hydroid in which the rate of catch-up growth increased with the amount of stress to which the animals had been exposed. The exact cost of compensatory growth cannot be calculated because oxygen consumption and growth were not measured simultaneously. However, on the basis of data and calculations reported by Wieser & Medgyesy (1990) it appears that compensatory growth, if fuelled by the metabolic power indicated by our measurements of oxygen consumption, would have to be about twice as efficient as normal growth in the related species Rutilus rutilus.     

Oxidative phosphorylation in Micrococcus denitrificans

P/O ratios were measured in membrane particles obtained from cells of Micrococcus denitrificans, while growing on different carbon sources. The membrane particles obtained from cells growing actively on glucose, succinate, ethanol and propanol as the carbon and energy sources catalyzed oxidative phosphorylation and yielded respective P/O ratios of 1.4, 1.2, 0.8, and 0.5 with NADH, and 0.8, 0.6, 0.6, and 0.5 with succinate as the electron donors. Not such a difference in P/O ratio is observed in intact resting cells grown with different carbon sources. It is concluded that the influence of the carbon source is probably directed towards the efficiency of oxidative phosphorylation in membrane particles and not in the growing cells.For the aerobic carbon source-limited chemostat cultures the following maximum growth yields were determined: 40.2 and 34.2 for succinate and oxgen, 41.7 and 36.5 for malate and oxygen, 81.4 and 39.4 for mannitol and oxygen, and 77.8 and 43.4 for gluconate and oxygen respectively. With a mathematical model (de K waadsteniet et al., in press) the P/O ratio was valued at 1.4–1.7. Y _ATP at =0.2 was valued at 8.7–10.9; Y _ATP ^max at 9.6–13.2 and m _e at 0.6–4.5 for the most precise experiment (gluconate-limited). The calculation of these growth parameters has been discussed.     

Energetics of the growth of Methanobacterium thermoautotrophicum and Methanococcus thermolithotrophicus on ammonium chloride and dinitrogen

Methanobacterium thermoautotrophicum was grown in continuous culture in a fermenter gassed with H₂ and CO₂ as sole carbon and energy sources, and in a medium which contained either NH₄Cl or gaseous N₂ as nitrogen source. Growth was possible with N₂. Steady states were obtained at various gas flow rates with NH₄Cl and with and the maintenance coefficient varied with the gas input and with the nitrogen source. Growth of Methanococcus thermolithotrophicus in continuous culture in a fermenter gassed with H₂, CO₂ as nitrogen, carbon and energy sources was also examined.Abbreviations molecular growth yield (g dry weight of cells per mol of CH₄ evolved) - growth rate (h^-1) - D dilution rate (h^-1) - rate (h_-1); relation of Neijssel and Tempest and of Stouthamer and Bettenhaussen - energy     

Energy requirement for maintenance of the transmembrane potassium gradient in Klebsiella aerogenes NCTC 418: A continuous culture study

Molar growth yield studies on chemostat cultures of Thiobacillus neapolitanus grown in thiosulfate-minerals medium have confirmed earlier observations that the dry weight increased linearly with the dilution rate. The observed increase can be explained neither by a change in cell composition nor by the observed excretion of organic compounds. The increase of the molar growth yield over the full range of growth rates, that is also observed in other obligate chemolithotrophs, was not found in the facultatively chemolithotrophic Thiobacillus A2, grown on thiosulfate or formate. The interpretation of the results in terms of maintenance energy requirement is discussed. It is concluded that these results do not allow a mathematical treatment according to the empirical formula of Pirt.Abbreviation APS Adenosine-5-phosphosulfate     

We can eliminate invasions or live with them. Successful management projects

Pessimism about the prospects of eradicating invasive species or managing them at acceptably low densities is fostered by publicity about failures, but it is often unwarranted. Many species, including insects, plants, and aquatic invaders of various taxa, have been eradicated, and a variety of management techniques have maintained others at low densities for long periods. Many of these projects entailed low-tech, scorched-earth approaches, often using mechanical, physical, or chemical means. Others required sophisticated scientific research. There are at best rough guidelines rather than general rules about what approach to undertake. It is therefore important in each case to consider the full range of possible methods for eradication or long-term control, including the possibility of marshalling a massive amount of physical labor.     

What is hemimethylated DNA?

De novo methylation of a CG dinucleotide pair by murine DNA methyltransferase is stimulated by the presence of a single methylcytosine positioned close to the target site.     

免疫的代价

免疫系统发育的代价主要是为B淋巴细胞和T淋巴细胞发育抗原识别多样性时的低效率过程提供能量 ,为开始形成白血球提供基质 (如氨基酸和脂肪 ) ,并为胚胎和雏鸟提供白细胞。维持免疫系统的代价与持续产生白细胞、免疫球蛋白以及其它血浆蛋白时的营养分配有关 ,这些血浆蛋白用于取代在正常的细胞代谢中丢失的蛋白质以及细胞间的蛋白质。利用免疫系统阻碍可能的病源体入侵的代价有两种主要形式。第一 ,由于白细胞参与效应子机制时发生的损害、组织整合性以及寄主细胞的存活力的损伤 ,组织功能有一些损失。第二 ,在活化相应类型的细胞并产生其效应子作用时存在着营养耗费。病源体挑战所带来的主要代价是系统的急性期反应(特别是肝脏的复原 )通过产生保护性的蛋白质来帮助免疫系统     

Maintenance behavior of cattle in a young tree plantation in southern Kyushu,Japan

This 4-year study monitored maintenance behavior of beef cattle (Japanese Black) foraging in a young Chamaecyparis obtusa (an evergreen conifer) plantation in southwestern Japan. The animals spent 551 ± 8 min (mean ± SE) per day grazing, 436 ± 4 min ruminating, 313 ± 9 min resting, 44 ± 2 min moving, and 96 ± 4 min on other activities. Grazing activity was high during 0600–1800 h and low during 2200–0600 h. Ruminating activity was high during 2200–0600 h and low during 0600–1800 h. Resting activity was high during 2200–0600 h and low for the remainder of the day. Air temperature was not a dominant factor determining the daily duration of grazing, rumination, or resting. The activity of the animals was usually synchronized, with the degree of synchronization being highest in grazing followed by ruminating and resting. Daily liveweight change of the animals was positively related with daily ruminating time, i.e., animals gained more when they ruminated longer. The maintenance behavior of cattle in the young tree plantation, as compared with that on grasslands, is characterized by (1) high grazing activity around midday, (2) low ruminating activity in the daytime, and (3) midday adjustment of the daily total grazing time. Daily rumination time may be used as an indicator of animal performance on the bases of a herd (not individual animals) and a period of 2–15 weeks (not individual days).     

Direct estimation of the oxygen requirements of Achromobacter xylosoxidans for aerobic degradation of monoaromatic hydrocarbons (BTEX) in a bioscrubber

The O₂ requirements for biomass production and supplying maintenance energy demands during the degradation of both benzene and ethylbenzene by Achromobacter xylosoxidans Y234 were measured using a newly proposed technique involving a bioscrubber. Using this approach, relevant microbial parameter estimates were directly and simultaneously obtained via linear regression of pseudo steady-state data. For benzene and ethylbenzene, the biomass yield on O₂, , was estimated on a cell dry weight (CDW) basis as 1.96 ±.25 mg CDW mgO₂ and 0.98 ±.17 mg CDW mgO₂, while the specific rate of O₂ consumption for maintenance, , was estimated as 0.041 ±.008 mgO₂ mg CDW^h and 0.053 ±.022 mgO₂ mg CDW^h, respectively.     

益生菌对维持性血液透析慢性肾脏病患者肠道菌群失调的影响

目的探究益生菌对维持性血液透析慢性肾脏病患者肠道菌群失调的影响,为此类患者的治疗提供参考。方法选取2017年4月到2019年4月我院收治的78例维持性血液透析慢性肾病患者,按照随机数字法分为观察组和对照组各39例。对照组患者给予常规治疗,观察组患者给予常规治疗联合益生菌。检测两组患者肠道菌群变化,同时检测血清炎性因子(IL6、TNFα、CRP)、肠道屏障功能(D乳酸、内毒素)及肾功能指标[肌酐(serum creatinine,Scr)、尿素氮(blood urea nitrogen,BUN)]水平。结果治疗后两组患者Scr、BUN水平均下降(均P<0.05),观察组与对照组比较有减少趋势,但差异无统计学意义(均P>0.05)。治疗后两组患者肠道双歧杆菌、乳杆菌数量均增加,大肠埃希菌、肠球菌数量均下降,且观察组患者改善情况优于对照组,差异有统计学意义(t=4.226、9.634、6.157、2.739,P<0.001、<0.001、<0.001、=0.008)。治疗后两组患者D乳酸、内毒素水平均降低,且观察组低于对照组,差异有统计学意义(t=2.856、3.125,P=0.007、0.003)。治疗后两组患者血清IL6、TNFα、CRP水平均下降,且观察组下降幅度更大,差异具有统计学意义(t=3.124、4.025、8.024,P=0.007、<0.001、<0.001)。结论益生菌对维持性血液透析慢性肾脏病患者肠道菌群失衡、肠道屏障功能和微炎症状态均具有改善作用,可为该类患者临床治疗提供一定参考。