An improved acriflavine-Feulgen method.

The acriflavine-Feulgen method for the histochemical demonstration of deoxyribonucleic acid was modified by staining hydrolyzed cells with 0.01% acriflavine dissolved in 90% ethanol. This method offered the following advantages: (a) it simplified the preparation of the acriflavine-Feulgen reagent; (b) it left the cytoplasm essentially unstained while staining the nuclei bright green in hydrolyzed cells and left the cytoplasm and nuclei essentially unstained in unhydrolyzed cells; (c) it eliminated poorly defined reagents from the staining solutions. Because of these staining properties, this technique may be especially useful in the quantitative determination of deoxyribonucleic acid by cytofluorometry.     

A general theory of life table construction and a precise abridged life table method

"In this paper we lay the foundation of life table construction by unifying the existing life table methods. We also present a new method of constructing current (period) abridged life tables.... The development includes (1) a careful formulation and computation of age-specific death rates, (2) derivation of a new set of formulas for computing the survivorship function from the observed age-specific death rates and populations, (3) estimation of the main life table functions by spline interpolation, integration and differentiation, and (4) use of a quadratic and a Gompertz function to close the life table.... The method is illustrated with construction of abridged life tables using Canadian data."     

An improved method of light-induced pigmentation.

An improved procedure was developed whereby a primary light signal can be intensified and made visible by activation of a pre-tyrosinase (pre-phenoloxidase) enzyme [isolated from silkworm (Bombyx mori)] by alpha-chymotrypsin; this activation results from the light-activated conversion of the inactive cis-cinnamoyl-alpha-chymotrypsin.     

An improved method for purifying sialidase.

An adsorbent specific for sialidase (EC 3.2.1.18) was prepared by coupling a glycoprotein containing glycosidically linked sialic acid to Sepharose. This adsorbent does not display the non-specific adsorption that occurs in previously reported methods.     

An improved method for screening alpha-acetolactate producing mutants.

Alpha-Acetolactate-deficient Lactococcus lactis ssp. lactis biovar. diacelylactis are utilised in several industrial processes for producing diacetyl and alpha-acetolactate. They can be selected by screening after random mutagenesis. We improved a previously described screening method [Monnet, C., Schmitt, P., Diviès, C., 1997. Appl. Environ. Microbiol. 63, 793-795], which makes it possible to screen up to 1000 colonies per agar plate, whereas the previous method allowed to screen only 60 colonies per agar plate. The new screening method facilitates selection of alpha-acetolactate-deficient mutants.     

An improved phycobilin extraction method

One unique feature in cyanoprokaryotes, rhodophytes, and cryptophytes is the presence of phycobilin pigments-these water soluble pigments can absorb red, orange, yellow, and green light enhancing the spectral range available for cellular conversion to chemical energy. The presence of phycobilin pigment complexes can be detected using fluorescence, or absorbance measures. Efficient detection of these compounds is essential for use in calibrating absorbance in remote sensing or in physiological studies. The standard procedure for phycobilin analysis involves sonication, extraction in buffer potentially coupled with additional digestion steps using enzymes, repeated freeze and thawing cycles, followed by filtration, and spectrophotometric analyses. An alternative method, using asolectin-CHAPS ((3-[(3-cholamidopropyl)dimethylammonio]propanesulfonic acid – AC)) solution for extraction, and three cycles of freeze/thawing/sonication, was compared to the phosphate buffer (PB) standard procedure. Cultures of both coccoid and filamentous cyanoprokaryota had improved extraction efficiency (38–80%) using AC. After two complete extractions, no pigment was detectable in AC and near baseline fluorescence was observed in the cell pellet, whereas the PB extraction method removed <90% of the phycobilins after two extractions. Phycocyanin concentration measured by AC extraction was better correlated to lipophilic pigment concentration than using phosphate buffer extraction. AC buffered to pH 6.7 was more effective than AC 3.75. One potential source of experimental error was determined to be the use of a baseline correction for the extraction buffer, not the sample.     

An improved method for repeated plasmapheresis in the rat.

An improved method for plasmapheresis in the rat was designed. The rat was anesthetized with ketamine hydrochloride, and venipuncture of the iliac vein was performed with a 21-ga butterfly infusion set with 12' of flexible tubing. Six ml of blood were drawn into a heparinized syringe and centrifugated. After the plasma was separated, the rbc were reinfused through the phlebotomy apparatus. This procedure was performed on each rat weekly for 10 wk without apparent harm to the animals. There were no changes in total serum protein and albumin, and body weights in most animals remained constant. This method should prove valuable in studies in which long-term plasmapheresis is indicated.