Characteristics of ribonucleic acids isolated for Botryodiplodia theobromae pycnidiospores

Pattern of ribonucleic acid synthesis during germination of Allomyces macrogynus mitospores

The relationship between ribonucleic acid (RNA) synthesis and germination of Allomyces macrogynus mitospores was investigated. It was determined that the synthesis of all classes of RNA was initiated during the first 10 min of germination, around the time of encystment. It is during this stage that the membrane of the nuclear cap structure begins to break down, dispersing the cell complement of ribosomes throughout the cytoplasm. After encystment, there was an increase in the rate of synthesis of the four stable RNA species (4S, 5S, 19S, and 27S) which leveled off as the germ tube emerged. Data suggested that messenger RNA was synthesized at an increasing rate during the course of germination. Studies of RNA precursor pool behavior and RNA synthesis in the presence and absence of actinomycin D indicated that no species of RNA, including messenger RNA, was synthesized in the presence of actinomycin D. Further, precursor pool measurement indicated that the apparent increase in the rate of RNA synthesis during germination was largely due to increased specific activity of the RNA precursor pool.

Properties of polyadenylate-associated ribonucleic acid from Saccharomyces cerevisiae ascospores

Bulk ribonucleic acid (RNA) was isolated from mechanically disrupted ascospores of Saccharomyces cerevisiae. After two passes over an oligo (dT10) cellulose column, the portion which bound, called poly(A)(+), was characterized. It is heterodisperse in size with a mean molecular weight of approximately 4 X 10(5), but contains some species as large as 7 X 10(5). The base composition is similar to vegetative poly(A)(+) RNA. The polyadenylate segment is also heterogenous in size, ranging from 90 to 20 bases in length, with a peak at approximately 60 nucleotides in length. Pulse-labeling of asci with [3H-methyl]methionine yields two "caps," 7-methyl guanosine-5'-triphosphoryl-5'-adenosine (or guanosine) identical to that found in vegetative poly(A)(+) RNA. The poly(A)(+) RNA in spores is found in polyribosomes which are, on the average, smaller than vegetative ones. Long-term labeling studies indicate that the fraction of poly(A)(+) RNA in spores is similar to that in vegetative cells.

Evidence for the presence of messenger ribonucleic acid in Allomyces macrogynus mitospores

Sucrose density gradient analysis was used to show that polysomes were present in the mitospores of Allomyces macrogynus. Fifty percent of the spore monosomes were shown to be resistant to dissociation by 0.8 M KCl, indicating that messenger ribonucleic acid (mRNA) was bound to them. These polysomes and all the spore ribosomes were contained in the nuclear cap. Only 4S RNA could be demonstrated in the extra-cap fraction. Hybridization studies using 3H-labeled polydeoxythymidylic acid indicated that polyadenylate was present to the extent of 0.08% of the total spore RNA. Sixty-eight percent of the polyadenylic acid is found in the nuclear cap, and 32% is found in the extra-cap fraction. It was demonstrated that [3H]uridine was taken up by the spores and converted to uridine triphosphate. Lack of incorporation of 3H into RNA indicated that the spores do not synthesize RNA. Thus, the mRNA found in spores is synthesized prior to spore formation.

Studies on the macroconidia of Microsporum canis. Characteristics of in vitro amino acid incorporating system

The characteristics of an in vitro polyuridylic acid dependent amino acid incorporating system prepared from germinating macroconidia of Microsporum canis are described. The incorporation of 14C-phenylalanine into polyphenylalanine is dependent on S-30 extract, adenosine triphosphate, magnesium ions and polyuridylic acid. Incorporation is slightly enhanced by yeast transfer ribonucleic acid and pyruvate kinase. The system is highly sensitive to ribonuclease, puromycin and miconazole (an antifungal agent), moderately sensitive to sodium fluoride and much less sensitive to phenethylalcohol, cycloheximide, chloramphenicol and deoxyribonuclease. Cell-free extract from ungerminated conidia has less capacity to synthesize the protein and during germination a marked increase in the protein synthetic activity is observed. The results from experiments wherein ribosomes and S-100 fraction from germinated and ungerminated spores are unterchanged, revealed that the defect in the extract from the ungerminated spore is in the ribosomes.