Relative Elemental Rates and Anisotropy of Growth in Area: a Computer Programme

A method of analysis of growth patterns in two dimensions haspreviously been proposed by Richarads and Kavanagh (1943),whichconsists of evaluating the divergence of velocity by vectoranalysis. The method has been adpted for solution by numericalmethods, and has been programmed for an electronic computer.The method and the programme are described, and applied to theanalysis of leaf growth in Xanthium. These preliminary resultssuggest that the system could be successfully applied to a widevariety of problem of 2-dimensional growth.     

Determination of Relative Rates of Solute Uptake by Cells

From Cell to Organism. D. KENNEDY (Readings from Scientific American) W. H. Freeman and Co. London, 1967. Reviewed by K. Mansford

Laboratory Methods in Microbiology. W. F. HARRIGAN and MARGARET E. McCANCE, Pp. xi + 362 + 22 figs. London and New York: Academic Press, 1966. 79s. Reviewed by D. G. Smith

Living Embryos. An introduction to the study of Animal Development. J. COHEN, Pp. vii+156 + 49 figs.+ 15 plates. Oxford: Pergamon Press. 1967. Revised 2nd Edition. 25s. Reviewed by A. S. G. Curtis

Classwork with Fungi. H. A. DADE and JEAN GUNNELL, Pp. 55 + 86 figs. Commonwealth Mycological Institute, 1966. 10s. Reviewed by Alison Leadley-Brown

Courtship: A Zoological Study. M. BASTOCK, Pp. viii + 220. London: Heinemann Educational Books, 1967. 25s. Reviewed by A. Barker

Fundamental Concepts of Biology. G. E. NELSON, G. G. ROBINSON and R. A. BOOLOOTIAN, Pp. x +331 + 330 figs. New York: John Wiley &; Sons, Inc. 1967. Reviewed by M. H. Williamson

The Evolution of Differentiation. W. S. BULLOUGH, Pp. vii + 206 + 32 figs. London and New York: Academic Press, 1967. 45s. Reviewed by B. Bracegirdle     

The Relative Growth Rates of Three Plankton Diatoms in Relation to Underwater Radiation and Temperature

Relative growth rates of three freshwater plankton diatoms-Asterionellaformosa, Fragilaria crotonensis, and Tabellaria flocculosa var.asterionelloides-are described from cultures suspended at variousdepths and during several seasons in the lake Windermere. Seasonalvariation in rates recorded near the surface (i m. depth) isinterpreted in terms of seasonal changes in temperature anddaylength. Rates recorded for Asterionella and Fragilaria aregenerally similar, but are approximately twice the rates obtainedwith Tabellaria. Depth profiles of relative growth rates areof similar form in all species, and normally show lightsaturationnear the surface. The shape of profiles for Asterionella isin good agreement with estimates of photosynthesis integratedover the growth periods. The parallelism between photosyntheticand relative growth rates of Asterionella is further illustratedfrom laboratory experiments: an approximate interconversion,under certain conditions, is given.     

A Note on the Estimation of Microbial Growth Rates from Rates of Substrate Utilization

A graphical method is described for estimation of the specific growth rates (μ) of microbial cultures during exponential growth under constant conditions from measurements of rates of substrate utilization or product formation.     

Determination of the Rate of Transformation from Growth Curves of Transformed Streptococci

A rapid method of determining the rate of transformation of group H streptococci to streptomycin resistance has been developed. The new technique, which involves analysis of the growth response of transformed streptococci in liquid medium containing streptomycin, is independent of chain length fluctuations and is demonstrably more accurate than the standard plating method. The relatively short generation time of streptococci under these conditions permits transformation rates to be estimated in 9 to 14 hr depending on the number of transformants in the inocula as compared to 50 hr by the agar plate procedure.     

Growth Analysis of Perennial Plants: The Relative Production Rate and its Yield Components

A new formulation for plant growth analysis, called the relativeproduction rate, is proposed for use in the study of perennialplants. The new measure and its yield components are similarto current growth analysis, but use the annual increment ofgrowth, rather than total accumulated growth, as the basis forassessing performance. The relative production rate removesaccumulated past growth of the perennating structure, a majordeterminant of relative growth rate, and acts independentlyof tree size as a measure of the vigour of growth. The multiplicativeyield components of this relative production rate also providebetter insight into the current morphological and physiologicalfeatures of the tree than the standard growth analysis formulations.Examples are given using Douglas-fir (Pseudotsuga menziesii(Mirb.) Franco) and red pine (Pinus resinosa Ait.) plantationsto illustrate the methodology proposed. Pseudotsuga menziesii (Mirb.) Franco, Pinus resinosa Ait., Douglas-fir, red pine, growth analysis, relative production rate, tree development, competition     

Separation of Respiratory Influences from the Tachogram: A Methodological Evaluation

The variability of the heart rate (HRV) is widely studied as it contains information about the activity of the autonomic nervous system (ANS). However, HRV is influenced by breathing, independently of ANS activity. It is therefore important to include respiratory information in HRV analyses in order to correctly interpret the results. In this paper, we propose to record respiratory activity and use this information to separate the tachogram in two components: one which is related to breathing and one which contains all heart rate variations that are unrelated to respiration. Several algorithms to achieve this have been suggested in the literature, but no comparison between the methods has been performed yet. In this paper, we conduct two studies to evaluate the methods'' performances to accurately decompose the tachogram in two components and to assess the robustness of the algorithms. The results show that orthogonal subspace projection and an ARMAX model yield the best performances over the two comparison studies. In addition, a real-life example of stress classification is presented to demonstrate that this approach to separate respiratory information in HRV studies can reveal changes in the heart rate variations that are otherwise masked by differing respiratory patterns.     

Plant Growth Analysis: A Re-examination of the Methods of Calculation of Relative Growth and Net Assimilation Rates Without Using Fitted Functions

A method is proposed for estimating expected values of meanrelative growth and net assimilation rates, and their variances,over an interval of time, from replicated plant weight and leafarea data at each end of the time interval. The advantage ofthe method is that it avoids the necessity of pairing replicateplants at each of the two harvests, and gives exact resultsfor relative growth rate. The results for net assimilation rateare approximate, but the method proposed still avoids the pairingprocess which is regarded as an artificial necessity inherentin the conventional method. net assimilation rate, relative growth rate, mathematical analysis, Helianthus annuusL, sunflower, Triticum aestiuumL, wheat     

A Photometric Method for Determining the Growth Rate of Yeast (Saccharomyces cereviciae)

There have been several investigations into students' conceptions of animal classification. Previous research has generally failed to study the criteria of classification used by the students. This study shows that students prefer to classify creatures along the criteria of habitat and locomotion (method of movement). They continue using these criteria even after learning the categories of biological taxonomy. The results lead to the assumption of an implicit theory of natural kinship of animals. The educational consequences for biology instruction, especially with regard to biological taxonomy, biodiversity, and evolution, are discussed.     

The Power of Relative Rates Tests Depends on the Data

One of the most useful features of molecular phylogenetic analyses is the potential for estimating dates of divergence of evolutionary lineages from the DNA of extant species. But lineage-specific variation in rate of molecular evolution complicates molecular dating, because a calibration rate estimated from one lineage may not be an accurate representation of the rate in other lineages. Many molecular dating studies use a ``clock test' to identify and exclude sequences that vary in rate between lineages. However, these clock tests should not be relied upon without a critical examination of their effectiveness at removing rate variable sequences from any given data set, particularly with regard to the sequence length and number of variable sites. As an illustration of this problem we present a power test of a frequently employed triplet relative rates test. We conclude that (1) relative rates tests are unlikely to detect moderate levels of lineage-specific rate variation (where one lineage has a rate of molecular evolution 1.5 to 4.0 times the other) for most commonly used sequences in molecular dating analyses, and (2) this lack of power is likely to result in substantial error in the estimation of dates of divergence. As an example, we show that the well-studied rate difference between murid rodents and great apes will not be detected for many of the sequences used to date the divergence between these two lineages and that this failure to detect rate variation is likely to result in consistent overestimation the date of the rodent–primate split. Received: 9 June 1999 / Accepted: 22 October 1999     

Determination of Maximal Growth Rate Using Continuous Culture1

Study of microorganism growth kinetics requires measurement of maximal specific growth rate. Standard methods of measurement-batch, semicontinuous and continuous steady state-have sources of imprecision that can be substantially reduced by a modification of the continuous steady-state method. Data are presented, using the ciliate Tetrahymena pyriformis, that indicate that the theoretical foundation of the new method is firm and that precision can be increased.     

Net Assimilation Rate Determines the Growth Rates of 14 Species of Subtropical Forest Trees

Growth rates are of fundamental importance for plants, as individual size affects myriad ecological processes. We determined the factors that generate variation in RGR among 14 species of trees and shrubs that are abundant in subtropical Chinese forests. We grew seedlings for two years at four light levels in a shade-house experiment. We monitored the growth of every juvenile plant every two weeks. After one and two years, we destructively harvested individuals and measured their functional traits and gas-exchange rates. After calculating individual biomass trajectories, we estimated relative growth rates using nonlinear growth functions. We decomposed the variance in log(RGR) to evaluate the relationships of RGR with its components: specific leaf area (SLA), net assimilation rate (NAR) and leaf mass ratio (LMR). We found that variation in NAR was the primary determinant of variation in RGR at all light levels, whereas SLA and LMR made smaller contributions. Furthermore, NAR was strongly and positively associated with area-based photosynthetic rate and leaf nitrogen content. Photosynthetic rate and leaf nitrogen concentration can, therefore, be good predictors of growth in woody species.     

Response of Insect Relative Growth Rate to Temperature and Host-Plant Phenology: Estimation and Validation from Field Data

Between 1975 to 2011, aphid Relative Growth Rates (RGR) were modelled as a function of mean outdoor temperature and host plant phenology. The model was applied to the grain aphid Sitobion avenae using data on aphid counts in winter wheat at two different climate regions in France (oceanic climate, Rennes (western France); continental climate, Paris). Mean observed aphid RGR was higher in Paris compared to the Rennes region. RGR increased with mean temperature, which is explained by aphid reproduction, growth and development being dependent on ambient temperature. From the stem extension to the heading stage in wheat, there was either a plateau in RGR values (Rennes) or an increase with a maximum at heading (Paris) due to high intrinsic rates of increase in aphids and also to aphid immigration. From the wheat flowering to the ripening stage, RGR decreased in both regions due to the low intrinsic rate of increase in aphids and high emigration rate linked to reduced nutrient quality in maturing wheat. The model validation process showed that the fitted models have more predictive power in the Paris region than in the Rennes region.     

Analysis of Mycelial Growth Rates and RAPD-PCR Profiles in a Population of Gaeumannomyces graminis var. tritici Originating from Wheat Plants Grown from Fungicide-treated Seed

Linear mycelial growth rates of 70 isolates of Gaeumannomyces graminis var. tritici on agar medium amended or unamended with the fungicide silthiofam were not correlated. Mycelial growth rate was not influenced by the fungicide applied to the seed of the plants from, which the isolates originated. DNA polymorphism determined by randomly amplified polymorphic DNA (RAPD) polymerase chain reaction was used to assess genetic variation among isolates. Thirty RAPD markers generated with five arbitrary 10‐mer primers revealed DNA polymorphism suitable for assessing variability in this fungal population. Cluster analysis of RAPD data identified two groups at the 54% similarity level. There was a significant relationship between the presence of 11 markers and sensitivity to silthiofam.     

Determination of In Situ Bacterial Growth Rates in Aquifers and Aquifer Sediments

Laboratory and field-scale studies with stained cells were performed to monitor cell growth in groundwater systems. During cell division, the fluorescence intensity of the protein stain 5-(and 6-)-carboxyfluorescein diacetate succinimidyl ester (CFDA/SE) for each cell is halved, and the intensity can be tracked with a flow cytometer. Two strains of bacteria, Comamonas sp. strain DA001 and Acidovorax sp. strain OY-107, both isolated from a shallow aquifer, were utilized in this study. The change in the average generation or the average fluorescence intensity of the CFDA/SE-stained cells could be used to obtain estimates of doubling times. In microcosm experiments, the CFDA/SE-based doubling times were similar to the values calculated by total cell counting and were independent of cell concentration. Intact and repacked sediment core experiments with the same bacteria indicated that changes in groundwater chemistry were just as important as growth rates in determining planktonic cell concentrations. The growth rates within the sediment cores were similar to those calculated in microcosm experiments, and preferential transport of the daughter cells was not observed. The experiments indicated that the growth rates could be determined in systems with cell losses due to other phenomena, such as attachment to sediment or predation. Application of this growth rate estimation method to data from a field-scale bacterial transport experiment indicated that the doubling time was approximately 15 days, which is the first known direct determination of an in situ growth rate for bacteria in an aquifer.     

杨柳田头菇交配型因子与菌丝生长速度关系

以杨柳田头菇（Agrocybe salicacola）菌株711子实体为材料,经担孢子弹射,用稀释分离法获得224个单孢菌株,其中单核菌株210个,交配试验及单孢出菇证明其性遗传模式为四极异宗结合,4种交配型的比例为AxBx∶AxBy∶AyBx∶AyBy为47∶59∶53∶51。研究结果还表明,杨柳田头菇4种交配型的数量、比例与单孢萌发速度、生长速度相关,生长速度较慢的菌株基本上属于一种交配型,只有少数生长慢的菌株属于另外两种交配型。值得注意的是,尽管快（F）-慢（S）配对的异核体与快（F）-快（F）配对的异核体在YPD平板上生长速度无明显差别,但在聚丙烯栽培袋上F-S异核体的生长速度明显快于F-F异核体,这说明交配因子A和B与生长速度基因可能连锁,且存在重组现象,F-S交配的异核体在生长上有优势,可能是人工选择后交配因子亚基减少导致偏分离发生的原因。     

Variation of Relative Growth Rate and Survival in Ecologically Contrasting Populations of Agrostis stolonifera

Abstract Significant differentiation in relative growth rate (RGR) was found among three ecologically contrasting populations of Agrostis stolonifera. Under low nitrogen conditions the sand dune population had the highest mean RGR. The plastic response in RGR to different levels of nitrogen supply was significantly higher in the inland meadow population than in the polder and sand dune populations. The (colonizing) polder population tended to have the highest variation for RGR. Variation in RGR within populations was mainly environmentally determined, although in the polder population significant effects of genotype and of genotype × nitrogen level were found. The repeatability for RGR in this population proved to be different from zero under both nitrogen conditions. Root/shoot ratios of the three populations were not different from each other, independent of the level of nitrogen supply. Correlations between RGR and survival of genotypes within the populations were not significant, which points at the influence of genotype × environment interactions or the possibility that genotypic differences in RGR do not necessarily indicate an adaptation to any habitat, not even the home site.     

温度对拟目乌贼幼体日生长率和存活率的影响

以温度为单因素变量,在人工饲养环境中,分析水温对拟目乌贼幼体日生长率与存活率的影响。实验结果表明,当水温处于28.1～32℃之间时,拟目乌贼幼体的日生长率与水温呈正相关关系;当水温处于32～32.67℃时,拟目乌贼幼体的日生长率与水温呈负相关关系;当水温处于29.5～32.6℃时,拟目乌贼幼体不易出现幼体死亡(死亡率<6.25%),适宜拟目乌贼幼体的存活;而当水温处于32.3～34℃之间时,拟目乌贼幼体出现了13.16%～61.16%的幼体死亡,不适宜拟目乌贼幼体的存活。实验结果表明,当水温处于29.5～32℃之间时,拟目乌贼幼体的存活率高(存活率>93.75%),且日生长率处于0.24%～1.76%,适宜拟目乌贼幼体的存活。