Assessing the amount of heterogeneity in random-effects meta-analysis

In a random-effects meta-analysis, a new confidence interval for the heterogeneity parameter is proposed. With this interval, the amount of heterogeneity in a meta-analysis can be assessed so that it can be judged whether the pooling of the estimates is meaningful. Through suitable corrections of the lower bound, based on the treatment effect measure of interest, the resulting interval yields satisfactory results with respect to the predefined confidence coefficient. Lower and upper bound of the interval can be used for one-sided hypothesis testing on the amount of the underlying between-trial variability.     

Manipulation of the amount of RNA in post-mitotic nuclei

Because all (or almost all) nuclear RNAs are liberated to the cytoplasm during mitosis and then return to the post-mitotic nuclei, we expected that if cytoplasm were amputated from mitotic cells the post-division nuclei would possess less than normal amounts of RNA. Experiments performed with amebae (A. proteus) show that this is in fact what happens. Furthermore, since the enucleate fragment cut from a mitotic cell possesses an “excess” of returnable nuclear RNAs, a normal interphase nucleus implanted into such mitotic cytoplasm might be expected to acquire above-normal amounts of RNA. Experiments reported here show that this expectation also is realized. Thus, the regulation of the normal nuclear concentration of these RNAs involves mechanisms other than a limited number of intranuclear “binding” sites and most likely is restricted by the rate of synthesis of these RNAs.The demonstration that nuclei can be depleted or enriched for RNAs, many of which are unique to nuclei, makes it possible to determine the consequences for cell metabolism of altered amounts of nuclear RNA. Hopefully, such studies will reveal the function(s) of these RNAs.     

饮茶摄氟量的探讨

饮茶摄氟量取决于三个要素：饮茶方式、茶氟富集量与氟浸出率,其中茶氟富集量是首要因素。茶水含氟量以一泡茶水最高,二泡茶水次之,三泡及其以后的茶水含氟量急剧下降。茶叶中富集的氟,基本上是水溶性化合物。饮茶过程中约有４２％～８６％的氟溶于茶汤被人体摄入。饮茶摄氟量关系到饮茶与人体健康,摄氟量过高,会造成氟中毒。     

稻-鸭复合生态系统产甲烷细菌数量

采用厌氧培养箱技术 ,用最大或然数计数法 (MPN法 )和滚管法同时测定稻 -鸭复合系统和常规稻作系统早稻不同生育期土壤中的产甲烷细菌数量。结果表明 :(1)两系统产甲烷菌数量具有明显的季节变化规律。水稻返青期前 ,两系统的产甲烷菌数量相差不大 ,随着水稻生育期的推进 ,两处理的产甲烷菌数量逐渐增加 ,均在分蘖盛期明显增高 ,孕穗期达到最高 ,乳熟期又显著减少 ,生长后期又有所回升。(2 )稻田围栏养鸭能减少稻田中的产甲烷菌数量 ,特别是减少了稻田甲烷排放高峰期的产甲烷菌数量。在水稻分蘖盛期和孕穗期 ,MPN计数法中 ,稻 -鸭复合生态系统低于常规稻作系统 2 0 .0 %～ 96 .9% ;滚管法计数中 ,前者比后者降低 33.3%～ 98.1% ,两系统的产甲烷菌数量之间的差异均达极显著水平。 (3)产甲烷细菌对甲醇、异丙醇、CO2 / H2 、乙酸钠有嗜好表现 ,对甲胺、甲酸、甲胺 甲醇 甲酸 异丙醇 乙酸钠 (混合基质 1)、甲酸 甲醇 异丙醇 乙酸钠 (混合基质2 )、甲醇 异丙醇 乙酸钠 (混合基质 3)有不适应的表现     

A method for determining in peacultures,the amount of molecular nitrogen fixed and the amount of combined nitrogen taken up from the soil

Summary A method has been described for the determination of the rate of nitrogen fixation when peas are grown in a soil from which they can take up combined nitrogen. This method is based on an earlier observation that previous nodule formation by an ineffective strain of the peaRhizobium H VIII prevents later nodulation by effective strains. Parallel pot experiments (muddy clay soil) in which pea plants were inoculated either with the ineffective strain VIII or with the effective strain H 47, showed that no effective nodules were produced by the former within a period of 2 months. Differences between the nitrogen contents of the peas in the two cultures can therefore be assumed to indicate the amount of atmospheric nitrogen fixed. Two successive oat crops were grown after the peas in order to determine the after-effect of the peas.The oats took up from the soil much more nitrogen than did the peas.     

Determination of plasmid copy number reveals the total plasmid DNA amount is greater than the chromosomal DNA amount in Bacillus thuringiensis YBT-1520

Bacillus thuringiensis is the most widely used bacterial bio-insecticide, and most insecticidal crystal protein-coding genes are located on plasmids. Most strains of B. thuringiensis harbor numerous diverse plasmids, although the plasmid copy numbers (PCNs) of all native plasmids in this host and the corresponding total plasmid DNA amount remains unknown. In this study, we determined the PCNs of 11 plasmids (ranging from 2 kb to 416 kb) in a sequenced B. thuringiensis subsp. kurstaki strain YBT-1520 using real-time qPCR. PCNs were found to range from 1.38 to 172, and were negatively correlated to plasmid size. The amount of total plasmid DNA (∼8.7 Mbp) was 1.62-fold greater than the amount of chromosomal DNA (∼5.4 Mbp) at the mid-exponential growth stage (OD₆₀₀ = 2.0) of the organism. Furthermore, we selected three plasmids with different sizes and replication mechanisms to determine the PCNs over the entire life cycle. We found that the PCNs dynamically shifted at different stages, reaching their maximum during the mid-exponential growth or stationary phases and remaining stable and close to their minimum after the prespore formation stage. The PCN of pBMB2062, which is the smallest plasmid (2062 bp) and has the highest PCN of those tested, varied in strain YBT-1520, HD-1, and HD-136 (172, 115, and 94, respectively). These findings provide insight into both the total plasmid DNA amount of B. thuringiensis and the strong ability of the species to harbor plasmids.     

Muscle force depends on the amount of transversal muscle loading

Skeletal muscles are embedded in an environment of other muscles, connective tissue, and bones, which may transfer transversal forces to the muscle tissue, thereby compressing it. In a recent study we demonstrated that transversal loading of a muscle with 1.3 N cm⁻² reduces maximum isometric force (F_im) and rate of force development by approximately 5% and 25%, respectively. The aim of the present study was to examine the influence of increasing transversal muscle loading on contraction dynamics.     

A long-term evolutionary pressure on the amount of noncoding DNA

A significant part of eukaryotic noncoding DNA is viewed as the passive result of mutational processes, such as the proliferation of mobile elements. However, sequences lacking an immediate utility can nonetheless play a major role in the long-term evolvability of a lineage, for instance by promoting genomic rearrangements. They could thus be subject to an indirect selection. Yet, such a long-term effect is difficult to isolate either in vivo or in vitro. Here, by performing in silico experimental evolution, we demonstrate that, under low mutation rates, the indirect selection of variability promotes the accumulation of noncoding sequences: Even in the absence of self-replicating elements and mutational bias, noncoding sequences constituted an important fraction of the evolved genome because the indirectly selected genomes were those that were variable enough to discover beneficial mutations. On the other hand, high mutation rates lead to compact genomes, much like the viral ones, although no selective cost of genome size was applied: The indirectly selected genomes were those that were small enough for the genetic information to be reliably transmitted. Thus, the spontaneous evolution of the amount of noncoding DNA strongly depends on the mutation rate. Our results suggest the existence of an additional pressure on the amount of noncoding DNA, namely the indirect selection of an appropriate trade-off between the fidelity of the transmission of the genetic information and the exploration of the mutational neighborhood. Interestingly, this trade-off resulted robustly in the accumulation of noncoding DNA so that the best individual leaves one offspring without mutation (or only neutral ones) per generation.     

SeqMap: mapping massive amount of oligonucleotides to the genome

SeqMap is a tool for mapping large amount of short sequences to the genome. It is designed for finding all the places in a reference genome where each sequence may come from. This task is essential to the analysis of data from ultra high-throughput sequencing machines. With a carefully designed index-filtering algorithm and an efficient implementation, SeqMap can map tens of millions of short sequences to a genome of several billions of nucleotides. Multiple substitutions and insertions/deletions of the nucleotide bases in the sequences can be tolerated and therefore detected. SeqMap supports FASTA input format and various output formats, and provides command line options for tuning almost every aspect of the mapping process. A typical mapping can be done in a few hours on a desktop PC. Parallel use of SeqMap on a cluster is also very straightforward.     

Estimating the amount of compositional change in late-Quaternary pollen-stratigraphical data

Detrended canonical correspondence analysis is used to estimate the amount of palynological change or compositional turnover in ten Holocene pollen-stratigraphical sequences from Setesdal, southern Norway. The results, when the analyses are standardised for the same time interval, show that the highest amounts of change occurred at sites in the south of Setesdal where there is a richer tree flora. This primarily methodological study provides a robust approach to answering the question as to how much change is recorded within a pollen sequence, and to summarising the amount of change between sequences.     

Influence of the amount of antigen and the interval on the secondary reaction

The course of the revaccination reaction in mice immunized with different doses of sheep red blood cells was determined at different intervals after the primary stimulus. The maximum level of haemagglutinating antibodies in the secondary reaction was found after a high primary and secondary antigenic stimulus. On the contrary, if the level of haemolytic antibodies was determined, the higher was the primary antigenic stimulus, the lower was the secondary antibody response. Differences between haemagglutinins and haemolytic antibodies were also manifested in the earlier onset of the maximum haemolytic secondary reaction (five months after the first dose of antigen); the maximum haemagglutination response was not attained until eight months after the primary dose of antigen. The results comfirm that the basis of preparation for the secondary reaction is proliferation of immunologically activated Y cells; differences in the haemolytic and haemagglutination response are related to differences in the character of the antigenic determinants of sheep red cells.     

Estimation of the amount of dietary starch available to different populations

The daily per capita availability of dietary starch was estimated for 38 selected countries using food disappearance data from the FAO provisional food balance sheets (1972-1974 average); starch availability was also estimated for Canada from 1960 to 1987 using Agriculture Canada disappearance data. Total starch availability varies fourfold among the difference countries; the availability of different sources of starch vary up to 80-fold. Wheat and roots-tubers were the major sources of starch in countries with low total starch availability. Either corn and pulses, rice and pulses, or wheat and potatoes were the major sources of starch in those countries with high total starch availability. Starch availability in Canada, both total and by source, has been relatively constant over the 27 years examined. Slight increases in total starch and starch from cereals and pulses in 1987 will need to be followed to determine whether these represent the beginning of a real change in per capita starch availability.     

Undermatching in humans to amount of reinforcement

Human subjects were exposed to a concurrent-chain procedure in which amount of reinforcement in the terminal links was varied. The experimental procedure was designed to resemble as closely as possible animal operant procedures: verbal instructions were eliminated, the key-press operant response was shaped, and a “consummatory” response was required to receive reward. In addition to varying amount of reward, three different pairs of initial-link values in the concurrent chain were studied. The human subjects showed undermatching to amount of reinforcement (as do animal subjects). Moreover, the degree of undermatching tended to increase as the values of the initial links increased, consistent with Fantino's delay reduction hypothesis (1977) that choice for a larger reward decreases as the length of the initial link increases.