Carl R. Merril

Mitochondrial DNA Sequence Analysis of Human Skeletal Remains: Identification of Remains from the Vietnam War

Deoxyribonucleic acid (DNA) sequence analysis of the control region of the mitochondrial DNA (mtDNA) genome was used to identify human skeletal remains returned to the United States government by the Vietnamese government in 1984. The postmortem interval was thought to be 24 years at the time of testing, and the remains presumed to be an American service member. DNA typing methods using nuclear genomic DNA, HLA-DQ alpha and the variable number of tandem repeat (VNTR) locus D1S80, were unsuccessful using the polymerase chain reaction (PCR). Amplification of a portion of the mtDNA control region was performed, and the resulting PCR product subjected to DNA sequence analysis. The DNA sequence generated from the skeletal remains was identical to the maternal reference sequence, as well as the sequence generated from two siblings (sisters). The sequence was unique when compared to more than 650 DNA sequences found both in the literature and provided by personal communications. The individual sequence polymorphisms were present in only 23 of the more than 1300 nucleotide positions analyzed. These results support the observation that in cases where conventional DNA typing is unavailable, mtDNA sequencing can be used for human remains identification.

Heat shock proteins protect against stress-related phosphorylation of tau in neuronal PC12 cells that have acquired thermotolerance

A68, or PHF-tau, is an abnormally phosphorylated form of the microtubule-associated protein tau, which is a primary protein constituent of paired helical filaments (PHFs) and, ultimately, of Alzheimers disease-associated neurofibrillary tangles (NFTs). Previously, we have shown that in heat-shocked neuronal PC12 cells, tau is hyperphosphorylated and transformed to an A68-like state as determined by immunologic and biochemical criteria. In the present study, we investigated the role of heat shock protein of 72 kDa (hsp72) in the protection of tau against hyperphosphorylation during heat shock. Neuronal PC12 cells were exposed either directly to a heat shock (45 degrees C for 30 min) or to a conditioning heat stress (43 degrees C for 90 min followed by a 4 hr recovery at 37 degrees C) followed by the heat shock. Hsp72 was maximally induced immediately after heat shock in conditioned (acquired thermotolerant, ATT) cells, while unconditioned (nonacquired thermotolerant, non-ATT) cells required 9 hr of recovery to exhibit maximal hsp72 induction. The differential time course of hsp72 induction during recovery of ATT and non-ATT cells correlated with the presence of normal tau. Immediately after the heat shock, when hsps were maximally induced, ATT cells exhibited the normal form of tau. With longer recovery times, the levels of hsp72 were reduced and tau was hyperphosphorylated. A similar correlation was observed in non-ATT cells. In the presence of L-azetidyl 2-carboxylic acid, ATT cells synthesized nonfunctional hsp72, as exhibited by the inability of the cells to recover from the effects of heat shock.(ABSTRACT TRUNCATED AT 250 WORDS)

Disco-ordinate expression of the Escherichia coli gal operon after prophage lambda induction

Abstract The three cistrons of the Escherichia coli gal operon are normally expressed co-ordinately. When the operon is transcribed from a prophage λ promoter, however, the expression is disco-ordinate. The product of the first cistron, galE , is found in much lower amounts than the products of the second and third cistrons, galT and galK . We find that the transcription of the operon under phage control is roughly co-ordinate, and conclude that the messenger RNA encoding galE is translated abnormally.

Reconstruction of protein and nucleic acid sequences: IV. The algebra of free monoids and the fragmentation stratagem

The problem of determining the sequence of a biopolymer from its fragments is stated in mathematical terms. Using concrete properties of a free monoid, certain general classes of biopolymers are shown to be insolvable from fragment data produced by complete digestion where enzymes specific for any possible combination of chemical bonds are employed.

On procaryotic gene expression in eucaryotic systems

SummaryNumerous types of interaction between pro-and eucaryotes exist in nature, from the endosymbiosis of some bacteria with unicellular organisms and insects to the complex systems of bacterial flora associated with the skin and intestines of animals and man, and nitrogen-fixation and crown-gall tumor induction in plants. Until recently, such interactions were not thought to include genetic transfer, but an increasing body of evidence points to the probability of similar naturally-occuring exchanges with wide-ranging implications for evolution and genetic manipulation.Experiments to elucidate the possible effects of procaryotic genes in eucaryotic systems have included in vitro and in vivo studies with both plant and animal systems, for instance the translation of bacterial messenger RNAs in the wheat germ and rabbit reticulocyte systems and the introduction of bacterial genes into plant protoplasts, animal cells and whole organisms.In the present paper we have tried to summarize the results of experiments involving the uptake, replication, transcription, translation and integration of procaryotic genes in various eucaryotic systems and to discuss the implications of such findings for basic research as well as for possible biomedical applications. Awareness of the possibility of procaryotic-eucaryotic genetic interactions may help to elucidate unresolved questions in pathology, such as possible involvement of the intestinal flora in carcinogenesis, as well as to provide valuable probes of eucaryotic control mechanisms and new approaches in agricultural genetic engineering.