Search PubMed⌕ Search

Biomedical subjects

E Jay

Publications and source records attributed to E Jay.

47 records · Page 3Linked to original sources
PubMed1976

Terminal labeling and addition of homopolymer tracts to duplex DNA fragments by terminal deoxynucleotidyl transferase.

Terminal deoxynucleotidyl transferase, which requires a single-stranded DNA primer under the usual assay conditions, can be made to accept double-stranded DNA as primer for the addition of either rNMP or dNMP, if Mg+2 ion is replaced by Co+2 ion. The priming efficiency in the presence of Co+2 ion with respect to initial rate tested with 2 single-stranded primer, is 5-6 fold higher than that observed with Mg+2 ion. In the presence of Co+2 ion, the primer specificity is altered so that all forms of duplex DNA molecules can be labeled at their unique 3'-ends regardless of whether such ends are staggered or even. Thus, using ribonucleotide incorporation, we have for the first time employed this reaction for sequence analysis of duplex DNA fragments generated by restriction endonuclease cleavages. Furthermore, by using Co+2 ion, it is possible to add a long homopolymer tract of deoxyribonucleotides to the 3'-terminus of double-stranded DNA. Therefore, without prior treatment with lambda exonuclease to expose the 3' terminus as single-stranded primer, this reaction now permits insertion of homopolymer tails at the 3'-ends of all types of DNA molecules for the purpose of in vitro construction of recombinant DNA.

Cobalt↗
PubMed1975

Influence of modified atmosphere storage on aflatoxin production in high moisture corn.

Samples of freshly harvested corn and remoistened corn were inoculated with Asphergillus flavus and stored for 4 weeks at about 27 C in air and three modified atmospheres. Aflatoxins and fat acidity were determined weekly. Corn stored in the modified atmospheres did not accumulate over 15 mug of total aflatoxins per kg. Corn from the high CO2 treatment (61.7 per cent CO2, 8.7 per cent O2, and 29.6 per cent N2) was visibly molded at 4 weeks and had a higher fat acidity than the other treatments. In the N2 (99.7 per cent N2 and 0.3 per cent O2) and controlled atmosphere (13.5 per cent CO2, 0.5 per cent O2, 84.5 per cent N2) treatments, a fermentation-like odor was detected. When the corn was removed from the modified atmospheres it deteriorated rapidly and was soon contaminated with aflatoxins.

Aflatoxins↗
PubMed1975

Survival of Aspergillus flavus and Fusarium moniliforme in high-moisture corn stored under modified atmospheres.

Freshly harvested high-moisture corn with 29.4% moisture and corn remoistened to 19.6% moisture were inoculated with Aspergillus flavus Link ex Fr. and stored for 4 weeks at about 27 C in air (0.03% CO2, 21% O2, and 78% N2) and three modified atmospheres: (i) 99.7% N2 and 0.3% O2; (ii) 61.7% CO2, 8.7% O2, and 29.6% N2; and (iii) 13.5% CO2, 0.5% O2, and 84.8% N2. Kernel infections by A. flavus, Fusarium moniliforme (Sheld.) Snyd. et Hans., and other fungi were monitored weekly. The modified-atmosphere treatments delayed deterioration by A. flavus and F. moniliforme, but their growth was not completely stopped. A. flavus survived better in the remoistened than in the freshly harvested corn. F. moniliforme survived in both. A. flavus and F. moniliforme were the dominant fungi in corn removed from the modified atmospheres and exposed to normal air for 1 week.

Air↗
PubMed1974

Chemical synthesis of a primer and its use in the sequence analysis of the lysozyme gene of bacteriophage T4.

We have developed a general approach for determining the nucleotide sequence of a gene, with the aid of a deoxyribonucleotide primer of defined sequence. The selection of the primer sequence was based on a short segment of mRNA sequence of T4 phage lysozyme. A tetradecadeoxyribonucleotide primer was chemically synthesized and its sequence verified by sequence analysis. This primer was found to bind to the single-stranded region of the exonuclease III-treated T4 DNA, and specific nucleotides were incorporated to its 3' end. The result indicated that this primer was bound to the expected location on the T4 DNA. Therefore, long sequences of the T4 lysozyme gene can now be determined from this specific starting point.

Base Sequence↗
PubMed1974

DNA sequence analysis: a formula to predict electrophoretic mobilities of oligonucleotides on cellulose acetate.

A simple method has recently become available for sequence analysis of large oligonucleotide fragments. Sequences are derived from the characteristic mobility shifts of the sequential partial degradation products of the oligonucleotide on two dimensional homochromatography. We have now developed an empirical formula for predicting the relative mobilities of each of the partial products in the first dimension (electrophoresis on cellulose acetate gel). The formula allows a more precise interpretation of the sequence of the oligonucleotide. It eliminates the ambiguities present in the method previously reported for sequence analysis by simple inspection of the mobility shifts. In order to amplify the mobility shifts so that they may be more easily and accurately measured, methods have been developed for preparing and fractionating the oligonucleotides on 40 x 40 cm DEAE-cellulose plates. Both improvements have proven valuable for direct sequence analysis by mapping.

Algorithms↗
PubMed1974

DNA sequence analysis: a general, simple and rapid method for sequencing large oligodeoxyribonucleotide fragments by mapping.

Several electrophoretic and chromatographic systems have been investigated and compared for sequence analysis of oligodeoxyribonucleotides. Three systems were found to be useful for the separation of a series of sequential degradation products resulting from a labeled oligonucleotide: (I) 2-D electrophoresisdagger; (II) 2-D PEI-cellulose; and (III) 2-D homochromatography. System (III) proved generally most informative regardless of base composition and sequence. Furthermore, only in this system will the omission of an oligonucleotide in a series of oligonucleotides be self-evident from the two-dimensional map. The sequence of up to fifteen nucleotides can be determined solely by the characteristic mobility shifts of its sequential degradation products distributed on the two-dimensional map. With this method, ten nucleotides from the double-stranded region adjacent to the left-hand 3'-terminus and seven from the right-hand 3'-terminus of bacteriophage lambda DNA have been sequenced. Similarly, nine nucleotides from the double-stranded region adjacent to the left-hand 3'-terminus and five nucleotides from the right-hand terminus of bacteriophage phi80 DNA have also been sequenced. The advantages and disadvantages of each separation system with respect to sequence analysis are discussed.

Base Sequence↗