Hepatitis viruses in southern Taiwan--mass survey of 2985 inhabitants

A survey of 2985 apparently healthy Taiwanese in southern Taiwan revealed a high prevalence (18.2%) of hepatitis B surface antigen (HBsAg). It was significantly higher in males (22.3%) than in females (13.6%), but no correlation with family origin, socioeconomic status or residence was established. About one-third of the breeding female HBsAg carriers were HBeAg-positive, and these may be an important source in the spread of HBV. Subtyping of HBsAg in 63 subjects showed adw to be dominant in this area, and 8 subjects with suspicious results had overlapping heterotypic HBV's (7 adwr and 1 adyw) in addition to 2 subjects in which coexistence of HBsAg and anti-HBs was recognized. The association between HBsAg positivity and serum transaminase elevation was significant, especially in the older groups who had a higher abnormal rate. Hepatitis A virus infection was serious too, with nearly 100% of people above 20 years of age being anti-HA antibody positive.

Non-nucleosomal packaging of a tandemly repeated DNA sequence at termini of extrachromosomal DNA coding for rRNA in Tetrahymena

A tandemly repeated DNA hexanucleotide sequence, 5'C-C-C-C-A-A3', that occurs at the termini of extrachromosomal DNA molecules coding for rRNA (rDNA) in Tetrahymena macronuclei was examined to determine whether it is packaged as nucleosomes. This repeated DNA sequence comprises the terminal few hundred base pairs at each end of the linear rDNA molecules. Digestion of macronuclei with micrococcal nuclease showed that this DNA sequence is protected from digestion but is left, following digestion, as a single but broad size class of DNA fragments several hundred base pairs long, under conditions in which bulk macronuclear DNA and rDNA were digested to fragments that were multiples of approximately 200 base pairs in length. The repeated C-C-C-C-A-A was found protected as fragments longer than the bulk macronuclear DNA digestion products at all times during digestion. Together with putative associated protein(s), this protected DNA was soluble after lysis of micrococcal nuclease-digested macronuclei at low salt concentrations but was insoluble in 0.075--0.2 M KCl, regardless of the extend of digestion. The size and solubility properties of the repeated C-C-C-C-A-A DNA nucleoprotein complex after micrococcal nuclease digestion of macronuclei are clearly distinguishable from those of nucleosomes, and it is inferred that this DNA sequence in macronuclei is packaged in chromatin by proteins other than histones.