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Biomedical subjects

D L Anderson

Publications and source records attributed to D L Anderson.

At least 109 records · Page 6Linked to original sources
PubMed1975

Genetic analysis of bacteriophage phi29 of Bacillus subtilis: mapping of the cistrons coding for structural proteins.

Four phage phi29 suppressor-sensitive mutants of cistron O have been examined for production of 14C-labeled viral-specific proteins in restrictive infections of Bacillus subtilis and fail to produce the protein of the viral neck lower collar. Cistrons O and F have been placed on the genetic map, containing 12 cistrons, by three-factor crosses. The phenotypes of five cistron J mutants have been analyzed by sodium dodecyl sulfate gel electrophoresis and autoradiography, and in three instances fragments of the normal polypeptide were detected. Three factor crosses with these mutants and a virus with a clear plaque phenotype were used to initiate the mapping of cistron J and the determination of the orientation of transcription in this map region.

Bacillus subtilis↗
PubMed1975

Morphogenesis of bacteriophage phi29 of Bacillus subtilis: cleavage and assembly of the neck appendage protein.

Each of the 12 neck appendages of the Bacillus subtilis bacteriophage phi29 consists of a single protein molecule with a molecular weight of about 75,000, and on the mature virion the appendages are assembled to the lower of two collars. The appendage protein is cleaved from a precursor protein, P(J), with a molecular weight of about 88,000. This cleavage is independent of neck assembly, occurring during infection by mutants that cannot synthesize the proteins of the upper and lower collars of the neck. The cleaved form of the appendage protein is efficiently complemented in vitro to particles lacking appendages. Thus, cleavage of the appendage precursor protein apparently does not occur in situ on the maturing virus.

Bacillus subtilis↗
PubMed1975

Sexual dimorphism in dentition mineralization.

This study determined for 121 boys and 111 girls of the serial experimental group of the Burlington Growth Centre the age, time interval and age sequence of 14 stages of mineralization of all tooth types. The two sexes differed significantly in the age at which the stages of tooth mineralization appeared, and in the length of the interstage intervals. In the canines, there was maximum sex difference in mineralization, which was almost 20 per cent and resulted from a delay in the boys. Changes in sequence of mineralization were due to delay rather than to acceleration. Sex differences in tooth mineralization manifested themselves before puberty, and mineralization was not accelerated at puberty. In contrast, post-pubertal mineralization of third molars appeared to be accelerated in both sexes and occurred earlier in the boys.

Age Factors↗
PubMed1975

Interrelationships of dental maturity, skeletal maturity, height and weight from age 4 to 14 years.

The correlations of dental mineralization stages, skeletal mineralization, body-height and weight were determined for each year between age 4 and 14 for 121 boys and 111 girls of the serial experimental group of the Burlington Growth Centre. Dental development related more strongly to morphological development than to skeletal development in both sexes, and skeletal age was more strongly related to morphological age than to dental stage. The relationship of individual teeth to skeletal age, height and weight were different but consistent in a sex-specific pattern. In males, both skeletal mineralization and dental mineralization, particularly of the first molars, were more closely related to height than to weight. In the females, skeletal and dental mineralization, especially of the second molars, were more closely related to weight from age 7 than to height. These relationships were significant in both pre-adolescent and adolescent years. In both these periods, skeletal age and body size related most strongly to late stages of tooth formation. Hence, from an early age, the stages of dental, skeletal and morphological maturation were significantly interrelated in a pattern that was specific for individual teeth and for sex.

Adolescent↗
PubMed1974

Analysis of bacteriophage phi 29 gene function: protein synthesis in suppressor-sensitive mutant infection of Bacillus subtilis.

Phage phi29 suppressor-sensitive (sus) mutants of 14 cistrons have been examined for production of (14)C-labeled viral-specific proteins in restrictive infections of Bacillus subtilis. Proteins specified by four cistrons (H, J, L, and N) have been resolved and identified by sodium dodecyl sulfate gel electrophoresis and autoradiography, and fragments of the normal polypeptides were detected. Mutants of six cistrons (C, D, E, F, I, and M) demonstrated two or more missing bands in the gel profiles, and thus some of these gene products may have regulatory functions. Mutation was detected in at least five genes coding for low-molecular-weight proteins, but a conditionally lethal mutant in only one of these genes has been isolated. Preliminary evidence that a precursor protein is cleaved to generate the neck appendage structural protein and a low-molecular-weight product has been obtained.

Amino Acids↗
PubMed1973

Selective replication of bacteriophage phi29 deoxyribonucleic acid in 6-(p-hydroxyphenylazo)-uracil-treated Bacillus subtilis.

Phage phi29 deoxyribonucleic acid (DNA) replicated under conditions where semiconservative DNA production in Bacillus subtilis host cells was blocked with 6-(p-hydroxyphenylazo)-uracil (HPUra). The time of initiation of phi29 DNA replication was not affected by HPUra, and normal quantities of viable phage were produced in the presence of the inhibitor. Studies with conditional lethal mutants of phage phi29 demonstrated the usefulness of HPUra for detection of viral-specific DNA production.

Azo Compounds↗
PubMed1973

Transcription during the development of bacteriophage phi29: definition of "early" and "late" phi29 ribonucleic acid.

Bacteriophage phi29 messenger ribonucleic acid (mRNA) production following infection of Bacillus subtilis has been analyzed. Early (e) phi29 RNA, made prior to the onset of phage deoxyribonucleic acid (DNA) replication and exclusively from the light (L) phi29 DNA strand, has been shown by RNA-DNA hybridization-competition experiments to be present throughout the phage latent period. No repression of e RNA production during phi29 development could be demonstrated. Unmodified host RNA polymerase molecules appear to be sufficient for the synthesis of e RNA since phage-specific RNA made in the presence of chloramphenicol hybridizes only to the L strand of phi29 DNA, and this RNA can be effectively competed during hybridization by e RNA. The appearance of late (l) phi29 RNA is coincident with the onset of viral DNA replication. This RNA consists of L DNA strand transcripts which are identical to e RNA and a new class of mRNAs made exclusively from the "heavy" (H) phi29 DNA strand (lH). Protein synthesis in infected cells is required for lH RNA production. Studies with the antibiotic rifamycin demonstrated that synthesis of the major phi29 structural proteins is dependent on production of lH RNA.

Amino Acids↗