Selection of a yeast strain with optimal utilization of straw hydrolyzates

The dry nonseparated straw hydrolyzates prepared by mild acid hydrolysis of milled straw contains 25--30% of reducing substances, mostly saccharides with prevalence of xylose. A strain utilizing the neutralized nonseparated hydrolyzates without any growth substances added was obtained by selection and long-term adaptation of an array of yeast strains. The strain, identified as Candida tropicalis 2838, exhibited high cell-growth rate and considerable yield of protein-rich biomass.     

The two-wavelength method of microspectrophotometry. II. A set of tables to facilitate the calculations

The calculations required for two-wavelength measurements are time consuming and laborious. In order to circumvent this limitation of the method, a set of tables which combined four operations into one has been designed and is reproduced within. The tables are based on Patau's formulae. The two transmission readings obtained according to the photometric method provide the coordinates which lead directly to a value for the relative absorbance. The product of this absorbance and the area of the photometric field gives the relative amount of chromophore in the field. The range of transmission values covered in the table corresponds to the effective range of the two-wavelength method.     

The two-wavelength method of microspectrophotometry. III. An extension based on photographic color transparencies

The two-wavelength method of microspectrophotometry corrects for distributional error and measures the amount of absorbing material by taking advantage of certain spectral characteristics of the specimen. Under certain circumstances, such as the absorption of nucleic acids in the ultraviolet and of black or multiple stains in the visible, the spectral characteristics are not suitable for the application of the method. To circumvent this, a photomicrograph of the object is taken with monochromatic light of a suitable wavelength. A second plate is exposed as a contact print of the photomicrograph and is developed in the presence of a coupling agent. After bleaching and fixation, the positive appears as a monochromatic color transparency. Two-wavelength analysis of such a transparency can be made in terms of the new color. The measurements will be free of distributional error and can be equated to the original object. The necessary formulae are derived, and a method which has proven suitable for color development is given. The photographic and the direct two-wavelength method were found to give equivalent results when both were used on the same series of liver nuclei. The application of the photographic method to ultraviolet absorption has been demonstrated. The new method is potentially applicable to other types of photographic densitometry involving heterogeneous images.     

The two-wavelength method of microspectrophotometry. I. A microspectrophotometer and tests on model systems

In spite of a number of examples of the apparently successful application of the two-wavelength method of microspectrophotometry to biological materials, a demonstration of the effective transition from the theoretical to the practical aspects of the method has never been given. The following tests were carried out on model systems in order to confirm the practical validity of the method: (1) Spherical droplets of Sudan blue or Sudan IV (varying in volume by as much as 400 times) were measured with the surrounding blank field included and were found to have amounts of chromophore which conformed to the estimated droplet volume to within 3 to 6 per cent. (2) Repeated determinations on the same isolated nucleus gave results which did not vary in spite of wide variations in the area of the photometric field. (3) The results of repeated determinations on the same droplet of dye were unaffected by gross changes in the focus of the objective. The microspectrophotometer on which these measurements were made has been briefly described; it was designed specifically for the two-wavelength method. Some of the details of instrumentation have been discussed, in particular, the effects of non-uniform illumination and the contrasting demands of the two integral parts of this type of photometry. Although it has certain limitations, the two-wavelength method conforms to its theoretical promise and is a practical method of measuring light absorption in complex objects.     

Determination of the optimal method of numerical taxonomy

A great number of numeric taxonomy methods, varying in the techniques of coding signs, similarity calculations and group analysis, as well as the insufficiency of criteria for the evaluation of numeric taxonomy methods, permitted us to propose the quantitative approach to the evaluation of the optimum method of numeric taxonomy. The dendrograms obtained by different methods were compared by calculating the measure of "proximity" which was assumed to be the sum of distances between divisions on different grouping levels.     

Factors affecting the estimation of the relative amount of chromophore and chromophore area by the two-wavelength method of patau and ornstein

Summary Factors influencing the calculation of the relative amount of chromophore and the chromophore area by the two-wavelength method are examined. The study was carried out with the help of models and further tested on Feulgen stained preparations. Except for certain restrictions the difference between the chromophore area as calculated from the two transmissions measurements and the chromophore area obtained by planimetry can be used as a guide for determining the proper measuring conditions, including the choise of the two wavelengths.     

大鼠睾丸组织固定法的优选研究

目的选择一种最优势、合理的固定方式以提高对睾丸组织制片效果,以配合不同种类的科学研究。方法选用10％甲醛溶液、NBF—Bouin’s、Bouin’s和改良Davidson’s四种不同的固定液对大鼠睾丸进行充分固定后,制作石蜡切片,进行HE染色,比较不同固定液中的睾丸组织学形态的差异;利用糖原特殊染色（PAS）,探讨不同固定液对睾丸糖原观察的影响;采用免疫组织化染色,测评睾丸组织内雄激素受体的固定效果。结果改良Davidson’8固定液较NBF—Bouin’s引起的曲细精管萎缩轻,形态更为清晰,用免疫组织化学方法检测雄激素更为敏感,并且改良Davidson＇s固定液在需要对精子发生进行分期时,其PAS染色的效果与Bouin＇s液固定后等同。结论与苴守圈常浦相№曲冉David0Rnn浦对女宙奥由的圈索特罩掂杯     

Factors affecting the estimation of the relative amount of chromophore and chromophore area by the two-wavelength method of Patau and Ornstein.

Factors influencing the calculation of the relative amount of chromophore and the chromophore area by the two-wavelength method are examined. The study was carried out with the help of models and further tested on Feulgen stained preparations. Except for certain restrictions the difference between the chromophore area as calculated from the two transmissions measurements and the chromophore area obtained by planimetry can be used as a guide for determining the proper measuring conditions, including the choise of the two wavelengths.     

Selection of an optimal system for measurement of blood pressure

The "pop-test" method was used to design an optimal system for precise measurement of fast arterial pressure oscillations by means of selecting optimal parameters of cardiovascular catheters and pressure transducers.     

Selection of optimal reference genes for normalization in quantitative RT-PCR

Background  

Normalization in real-time qRT-PCR is necessary to compensate for experimental variation. A popular normalization strategy employs reference gene(s), which may introduce additional variability into normalized expression levels due to innate variation (between tissues, individuals, etc). To minimize this innate variability, multiple reference genes are used. Current methods of selecting reference genes make an assumption of independence in their innate variation. This assumption is not always justified, which may lead to selecting a suboptimal set of reference genes.     

Selection of optimal DNA oligos for gene expression arrays.

MOTIVATION: High density DNA oligo microarrays are widely used in biomedical research. Selection of optimal DNA oligos that are deposited on the microarrays is critical. Based on sequence information and hybridization free energy, we developed a new algorithm to select optimal short (20-25 bases) or long (50 or 70 bases) oligos from genes or open reading frames (ORFs) and predict their hybridization behavior. Having optimized probes for each gene is valuable for two reasons. By minimizing background hybridization they provide more accurate determinations of true expression levels. Having optimum probes minimizes the number of probes needed per gene, thereby decreasing the cost of each microarray, raising the number of genes on each chip and increasing its usage. RESULTS: In this paper we describe algorithms to optimize the selection of specific probes for each gene in an entire genome. The criteria for truly optimum probes are easily stated but they are not computable at all levels currently. We have developed an heuristic approach that is efficiently computable at all levels and should provide a good approximation to the true optimum set. We have run the program on the complete genomes for several model organisms and deposited the results in a database that is available on-line (http://ural.wustl.edu/~lif/probe.pl). AVAILABILITY: The program is available upon request.     

Reconstituted skin in culture:a simple method with optimal differentiation

Human skin is a unique organ, which can be reconstituted in vitro and represents an interesting system for studying cell proliferation and differentiation. A simple technique for producing reconstituted skin with optimal epidermal differentiation is described and characterized. A 4-mm punch biopsy of normal human skin is deposited on the epidermal side of mortified de-epidermized human dermis maintained at the air-liquid interface with a metallic support. The culture medium contains insulin, epidermal growth factor (EGF), cholera toxin, hydrocortisone, penicillin/streptomycin and fungizone. A well-differentiated epidermis develops within 15 days. Morphological and ultrastructural studies show a neoepidermis resembling normal skin. Differentiation markers such as involucrin, filaggrin, and various cytokeratins detected with pancytokeratin antibody are present and confirm this resemblance. The keratin profile is comparable to that observed in other skin culture models. A basement-membrane-like structure is reconstituted with hemidesmosomes and anchoring-filament formation. Bullous pemphigoid (BP) antigen is observed at the dermo-epidermal junction after 21 days of culture. Moreover, both dermal substrates and punch biopsies can be kept frozen for long-term storage, with little or no loss of epidermal growth kinetics and morphology. This skin culture technique is rapid, simple, economical and reproducible. Characterization has here shown high-quality epidermal differentiation. Scientists interested in epidermal in vitro studies should take interest in all these advantages.