Tatsuichi Iwamura

High-flow-rate hydroxylapatites

We have established a novel and simple method for preparing rigidly crystallized or granulated hydroxylapatites, which showed flow rates one order of magnitude higher in column chromatography than those of the Tiselius specimen (1). The essential difference in the procedures from the Tiselius method is that calcium phosphate, the precursor of hydroxylapatite, is generated not at room temperature but at either 45 or 95 degrees C. The capacities of the two hydroxylapatites for binding and fractionating protein, RNA, and DNA upon column chromatography were similar to those of Tiseliuss hydroxylapatite. The 95 degrees C specimen can be dried with no change in the properties. Because of the reproducibly observed properties, including the extremely high flow rate with ease in handling as well as low cost and simple procedures with no additives and with no special equipment in preparation, our hydroxylapatites seem to be best so far for routine laboratory use.

Unique repetitive sequences of 170 bp inChlorella

SummaryCot analysis ofChlorella DNA revealed that the genome of the unicellular green alga contained a small amount of repetitive sequences (at most 15% of the total DNA). Short repetitive sequences (SRS) of 170 bp produced by enzymatic digestion of algal DNA with eitherHaeIII,HinfI, orPstI, were found by polyacrylamide gel electrophoresis, and their copy number was estimated to be a few hundred (about 2% of the total repetitive sequences). All three members showed high sequence homology and could be be unified into one family, ‘HaeIII family’. The family was divided further into two subfamilies,HinfI- (HaeIII-andHinfI-SRS) andPstI-(PstI-SRS) subfamilies, based on small sequence differences among the members. TheHaeIII family had characteristic structural features, including a considerable number of small unique sequence units (purine-CC) and both direct and inverted repeats, and were organized in tandem arrays in the genome.

Exclusion chromatography with controlled-pore glass beads to isolate Chlorella chromatin and its applications

A simple and rapid method was developed to isolate chromatin from the unicellular alga, Chlorella, by exclusion chromatography utilizing controlled-pore glass beads. This method takes advantage of the giant size of the chromatin supramolecules and does not require the preliminary isolation of cell nuclei. In order to raise the histone yield, commercially available materials were silanized with dimethyldichlorosilane. The isolated algal chromatin had properties similar to those of other organisms, and the histones contained all five components found in calf thymus. A hierarchy of the higher order structures was also observed in the algal chromatin. This method can be used for the study of chromatin in various cell types, especially in microbial cells, from the viewpoints of not only mere preparation but also cell dynamics and fractionation in relation to the specific components or activities. Some application examples are presented.