A direct solubilization procedure for the determination of DNA and protein in cultured fibroblast monolayers

A procedure for the direct solubilization of fibroblast monolayers allowing precise determination of DNA and protein content has been developed. This simple procedure is applicable to the analysis of these macromolecules in fibroblast cultures containing small numbers of cells (<1 × 10⁵).     

Rapid sex identification method of spinach (Spinacia oleracea L.) in the vegetative stage using loop-mediated isothermal amplification

Planta - A LAMP-mediated, simple and rapid method for sex identification in spinach was developed. Nutrient compositional analysis showed a higher iron content in male than female plants. Spinach...     

Analysis of the immunoadjuvant octadecyl tyrosine hydrochloride

A simple, rapid, high performance liquid chromatographic (HPLC) method for the analysis of the immunoadjuvant octadecyl tyrosine hydrochloride is described. The HPLC procedure can be applied to the direct determination of amino acid reactants present as contaminants in the adjuvant (tyrosine, ethyl tyrosine) and from this information the content of octadecanol reactant can be estimated. Further, these same determinations provide a means of monitoring immunoadjuvant stability in any vaccine preparation.     

Evaluation of the time course of neurotransmitter release from the measured PSC and MPSC

A method for obtaining delay histograms for the time course of neurotransmitter release is presented. The delay histogram is derived from the measured psc (or the sum of several psc's) and the mpsc (obtained experimentally or otherwise) by means of a simple, quick, mathematical procedure. The procedure may be automated for the greater part. No approximation of the mpsc shape is performed, and the method is applicable to all quantal contents. For low and medium quantal contents, the delay histograms obtained by the method are compared to those obtained by direct analysis. A reasonable agreement is achieved. An experiment of high quantal content, for which direct analysis is impossible, is then analysed using the new method. Difficulties which may arise when applying the procedure and methods to overcome them are discussed at length. Other methods are set forth in the Discussion.     

A diallel cross analysis of gum content in barley (Hordeum vulgare)

Summary A diallel cross analysis of gum content in barley (Hordeum vulgare) was made using six cultivars of two-rowed spring barley as parents. A Jinks-Hayman analysis of F2 progeny means showed that gum content was controlled by a simple additive-dominance genetic system and that low gum content was strongly dominant. The analysis suggested that gum content was principally controlled by two or three genes showing a high degree of dominance. Some genotype-environment interaction was detected in a comparison between the F2 and F3 generations which were grown in different years and locations. However, the character was found to be highly heritable both within and between generations, suggesting that the selection and breeding of barleys of reduced gum content should not be difficult.     

On the Evolution of Behavioral Heterogeneity in Individuals and Populations

A wide range of ecological and evolutionary models predict variety in phenotype or behavior when a population is at equilibrium. This heterogeneity can be realized in different ways. For example, it can be realized through a complex population of individuals exhibiting different simple behaviors, or through a simple population of individuals exhibiting complex, varying behaviors. In some theoretical frameworks these different realizations are treated as equivalent, but natural selection distinguishes between these two alternatives in subtle ways. By investigating an increasingly complex series of models, from a simple fluctuating selection model up to a finite population hawk/dove game, we explore the selective pressures which discriminate between pure strategists, mixed at the population level, and individual mixed strategists. Our analysis reveals some important limitations to the ESS framework often employed to investigate the evolution of complex behavior.     

A simple method for the determination of heparin content in heparin--sepharose.

A potentiometric titration method for the determination of heparin content in heparin-Sepharose is suggested. The procedure is simple and rapid.     

TLC-densitometric analysis of artemisinin for the rapid screening of high-producing plantlets of Artemisia annua L

A simple TLC-densitometric technique has been developed for the rapid and accurate analysis of artemisinin in a large number of Artemisia annua plantlets cultured in vitro. This new analytical method is based on the structural conversion of artemisinin on a silica gel layer by ammonia vapour to form 10-azadesoxyartemisinin, a chromophore-containing compound (lambdamax 320 nm) that can be detected by UV-based TLC densitometry. The TLC system was evaluated quantitatively in terms of product stability, precision, accuracy and calibration. Good linearity was obtained in the range of 0.01-0.12 microg artemisinin. The technique appeared to be accurate and sensitive as compared with the complicated pre-column reaction-HPLC technique. Among 90 samples of A. annua plantlets, the artemisinin content in the leaves appeared to be highly variable, ranging from 0.02 to 0.67% w/w dry weight. These results demonstrate that densitometric TLC can be a cheap and simple technique for the accurate screening of high-artemisinin-producing plants.     

Seston composition and the potential for Daphnia growth

A field survey was conducted to study the relationships amongst the composition of the seston, the nutritional value of the seston for herbivorous zooplankton (Daphnia), and selected water clarity parameters. Sixteen ponds in a wetland area and seven larger lakes, all located in south central Saskatchewan, Canada, were sampled for seston. The phytoplankton species were identified, and various biochemical seston variables were measured. A biotest using the zooplankter Daphnia magna, was employed to assess the nutritional value of the seston. The best seston variable to explain Daphnia growth was the phospholipid content (simple linear regression analysis: R ² _adj = 0.50). The water absorbance ratio A250/A365 was a good predictor of lipid content of the seston. Both the absorbance ratio A250/A365 and the dissolved organic carbon (DOC) concentration were negatively correlated with Daphnia growth. We hypothesize that the penetration of visible and ultraviolet radiation is an important determinant of seston quality, especially the phospholipid content, and that this has important implications for determining ultimate growth rates of herbivorous zooplankton.     

Evaluation of the normal equations for the analysis of diallels

Summary Analysis of diallel experiments usually requires specialised computer programs. A simple relationship between the normal equations for a diallel and the normal equations for a hypothetical model in which the general combining ability factor is viewed as two separate distinct simple factors may be useful in adapting general statistical analysis packages to the desired analysis.     

Purification and analysis of the major components of chum salmon protamine contained in insulin formulations using high-performance liquid chromatography

A simple high-performance liquid chromatographic method has been developed for the rapid purification and analysis of protamine components contained in insulin formulations. Only a single step is needed to separate peptides whose compositions, sizes, and unusual isoelectric points (pI 13.8) are nearly identical. The method involves their isocratic separation on a reversed-phase column using a pH 2 phosphate buffer and a low acetonitrile content as an eluant. The purified chum salmon components were analyzed by amino acid analysis, solid-phase amino acid sequencing, carboxypeptidase B digests, insulin complexation analysis, and a mass spectrophotometric procedure which gives an accurate mass of the intact peptides. This HPLC purification technique may also be applicable to protamines and other highly basic peptides isolated from other sources.     

A sensitive method for estimating the carbohydrate content of glycoproteins

A spectrophotometric method is described for estimating the carbohydrate content of acid-hydrolyzed glycoproteins. The method is based on the alkaline ferricyanide reaction with reducing sugars and is accurate in the 1–25 nmole range. Using a simple two-step ion-exchange column procedure both the total sugar content and the proportion of neutral and amino sugars can be determined.     

Crisis in Biology An Examination of the Deficiencies in the Current Pattern of Expansion in Biological Education

A method of analysing the content of biology curricula, courses, and texts on the basis of the relative emphasis laid on different levels of biological organization, is discussed. It is suggested that this method may have led to unwarranted contrasts between ‘traditional’ and ‘modern’ curricula. A simple modification to this method is proposed.     

Nitrogen partitioning and assimilation: methods for the extraction, separation and mass spectrometric analysis of nitrate, amino acid and soluble protein pools from individual plants following 15N labelling

A simple procedure is described for the separation of nitrate, amino acid and soluble protein pools in small volumes of plant extract. Recent developments in mass spectrometry and automated, on-line sample preparation facilitate the precise analysis of the ¹⁵N content of samples containing low concentrations of N (≤5 to ≥50μg) with enrichments close to the natural abundance level. When combined, these separation and analysis techniques make it possible to investigate and quantify the relationships between nitrogen uptake, storage, assimilation, and partitioning between discrete pools of N within individual plants, following ¹⁵N labelling.     

单头灰飞虱体内水稻条纹叶枯病毒的快速检测

利用RT-PCR检测感病植株和单头带毒灰飞虱,均扩增出水稻条纹叶枯病毒特有的一个长540 bp的片段,且人工饲毒虫的病毒含量高于自然感病稻田虫。以病毒S蛋白的多克隆抗血清,采用Western印迹技术从单虫体内检测到病毒抗原的2个专一性条带,大小分别为20.7和19.7 kDa。DIBA（dot immunobinding assay）检测法快速、简便,但专一性和灵敏度不及RT-PCR与Western印迹检测。对不同检测方法所得昆虫带毒率差异的原因进行了探讨。     

Simplified method for estimation of microbial activity in compost by ATP analysis

A simplified method using ATP analysis was proposed to estimate the time course of microbial activity during composting. A compost sample was suspended in distilled water and its filtrate was used to estimate the ATP content in the compost by the luciferine-luciferase fluorescence reaction. The method permitted the rapid and simple determination of ATP in the compost and was successfully applied to monitor the time course of the microbial activity in the laboratory-scale composting process. The analytical simplicity in this method greatly improved the field-applicability of the ATP analysis for the composting process monitoring.     

Development of a digital image analysis method for real-time estimation of chlorophyll content in micropropagated potato plants

The present work describes a digital image analysis method based on leaf color analysis to estimate chlorophyll content of leaves of micropropagated potato plantlets. For estimation of chlorophyll content, a simple leaf digital analysis procedure using a simple digital still camera was applied in parallel to a SPAD chlorophyll content meter. RGB features were extracted from the image and correlated with the SPAD values. None of the mean brightness parameters (RGB) were correlated with the actual chlorophyll content following simple correlation studies. However, a correlation between the chromaticity co-ordinates ‘r’, ‘b’ and chlorophyll content was observed, while co-ordinate ‘g’ was not significantly correlated with chlorophyll content. Linear regression and artificial neural networks (ANN) were applied for correlating the mean brightness (RGB) and mean brightness ratio (rgb) features to chlorophyll content of plantlet leaves determined through a SPAD meter. The chlorophyll content as determined by the SPAD meter was significantly correlated (RMSE = 3.97 and 3.59, respectively, for linear and ANN models) to the rgb values of leaf image analysis. Both the models indicate successful prediction of chlorophyll content of leaves of micropropagated plants with high correlation. The developed RGB-based digital image analysis has the advantage over conventional subjective methods for being objective, fast, non-invasive, and inexpensive. The system could be utilized for real-time estimation of chlorophyll content and subsequent analysis of photosynthetic and hyperhydric status of the micropropagated plants for better ex vitro survival.     

Mathematical model of the simple cells in the visual cortex

A mathematical model for the spatial computations performed by simple cells in the mammalian visual cortex is derived. The construction uses as organizing principles the experimentally observed simple cell linearity and rotational symmetry breaking, together with the constraint that simple cell inputs must effectively be ganglion cell outputs. This leads to a closed form expression for the simple cellkernel in terms of Jacobi-functions. Using a-function identity, it is also shown how Gabor sampling arises as an approximation to this exact kernel for most cells. In addition, the model provides a natural mechanism for introducing the type of nonlinearity observed in some simple cells. The cell's responses to a variety of visual stimuli are calculated using the exact kernel and compared to single cell recordings. In all cases, the model's predictions are in agreement with available experimental data.Work supported by the National Science Foundation, grant PHYS86-20266Work supported by the Department of Energy, contract DE-AC02-76ERO2220     

An Analysis of the Heterogeneity of Albumin

A simple and rapid procedure for characterization of serum albumin samples and for the isolation of fractions from fresh serum or commercial sources has been developed, based on DEAE Sepharose CL-6B ion exchange chromatography. Characterization of the fractions included sulfhydryl analysis, gel electrophoresis, and immunoelectrophoresis. Both analytical and preparative procedures were used. It has been shown that the relative content of the fractions varies from individual to individual. It has also been shown that certain fractions found in commercial preparations are artifacts which should be removed before performing serious studies with serum albumin.     

用一个相对简单的方法来探测核苷酸替代模型的异质性

对于可观察到的分子序列进化模型的不同,提出一个相对简单的方法——卡方检测,来检测在DNA序列间替代过程的同质性。这个卡方检测方法不管在座位间下列3个条件是否满足皆是成立的：（1）替代率的异质性;（2）进化率／模型的相关性;（3）替代模型的变异。计算机模拟也显示出卡方检测在各种生物学条件下的序列进化模型是非常有效的。在真实数据中,11种节肢动物线粒体DNA的比较中发现,水蚤或卤虫与其他9种节肢动物以高百分比违背了同质性进化模型假设,显然是由于AT含量高而引起的,且在两种蚊子的线粒体DNA比较中发现,其满足同质性假设仅有7．69％。还比较了卡方淦测与Kumar and Gadagkar的ID检测之间的效能差异：在较为复杂的模型下,卡方检测效率在许多情况下较ID检测方法略高;并且在犯Ⅰ-型错误以及卡方测验的效率曲线中清楚地表明我们的方法是保守的,而Kumar等的方法是不保守的。