Biomedical subjects

F H Wilt

Publications and source records attributed to F H Wilt.

At least 37 records · Page 2Linked to original sources

PubMed1986

Patterns of maternal messenger RNA accumulation and adenylation during oogenesis in Urechis caupo.

We have investigated the accumulation and adenylation of the maternal mRNA during oogenesis in the oocytes of the marine worm Urechis caupo. The analysis, using in vitro translation and cDNA probes to assay for specific mRNAs, demonstrates that different maternal mRNAs accumulate with different patterns during oogenesis. One class of maternal mRNAs accumulates throughout oogenesis and remains at a steady level in the full-grown oocyte. These mRNAs do not have a poly(A) tail long enough to mediate binding to oligo(dT)-cellulose in oocytes, but are rapidly adenylated immediately following fertilization. The other maternal mRNAs accumulate in growing oocytes as poly(A)+ RNA and undergo some deadenylation in full-grown oocytes and embryos. Some of these mRNAs attain their highest concentration fairly early in oogenesis, while others continue to accumulate during later stages. Many of the mRNAs that accumulate as poly(A)+ RNA in growing oocytes diminish dramatically in concentration in full-grown oocytes.

Animals↗

PubMed1984

The role of RNA polymerase initiation and elongation in control of total RNA and histone mRNA synthesis in sea urchin embryos.

The involvement of RNA polymerase initiations in regulating total RNA synthesis and the synthesis of the early histone mRNAs was investigated. Nuclei were isolated from developing sea urchin embryos from 4- to 600-cell stages, and the transcription of already initiated polymerase complexes was studied in a "run-off," or elongation, assay; this assay was optimized by using high levels of ribonucleoside triphosphates. Under these conditions the relative levels of RNA synthesis in isolated nuclei from different stages closely paralleled the known rates of synthesis in vivo. However, if sarkosyl is included in the elongation assay, the nuclei of older stages display greatly stimulated synthesis while early cleavage stage nuclei are not stimulated. Sarkosyl does not reveal any elongated transcripts from the early histone genes in nuclei from later stages of development. This has been interpreted to mean that there are many initiated polymerase II complexes that do not elongate rapidly at later stages, but the early histone genes are inactive at later stages because they do not possess any productively initiated polymerases.

Animals↗

PubMed1982

The program of Hl histone synthesis in S. purpuratus embryos and the control of its timing.

The program of Hl histone synthesis was investigated in Strongylocentrotus purpuratus embryos in order to determine when the late Hl histones are synthesized. The embryos were staged by cell number, morphological stage, and chronological age. Care was taken to ensure that conditions of rearing the embryos remained consistent. Labelling with 3H-lysine revealed that two forms of early Hl (Hl alpha 1 and Hl alpha 2) are synthesized from early cleavage stages (16-32 cells) to the blastula stage. Hl alpha 1, synthesis ceases first at around 400 cells (hatching blastula); Hl alpha 2 continues to be synthesized by the blastula but is usually absent from the labelling pattern in early gastrula (700 cells). Two forms of late Hl appear sequentially during the pre-hatching blastula stage. Hl gamma appears at 200-250 cells and Hl beta approximately 1 hr later, at 250-300 cells. The late forms of H2A and H2B are first synthesized at around hatching, several hours after late Hl forms appear. The time of synthesis of late Hl is strictly controlled by a chronological clock and is not affected by disruption of the cell cycle, cessation of DNA synthesis, or alteration of nucleocytoplasmic ratios. Polyspermic embryos and hydroxyurea-arrested embryos followed the normal temporal program of onset of late Hl synthesis.

Animals↗

PubMed1982

Direct measurement of histone peptide elongation rate in cleaving sea urchin embryos.

Regulation of protein synthesis can be exercised at a number of levels. One of the more experimentally difficult levels to approach has been the measurement of peptide elongation rate. This paper presents a new application of the cyanogen bromide (CNBr) cleavage of proteins in a direct measurement of histone peptide elongation rate in cleaving sea urchin embryos (Strongylocentrotus purpuratus). The data indicate an elongation rate (at 15 degrees C) for histones H2B and H1 alpha of 0.69 and 0.80 codons per s, respectively. These values fall within the range of previously published values of average peptide elongation rate for total protein in these cells. This method should be generally applicable to many systems for which the measurement of peptide elongation rate may provide a key to the understanding of the regulation of protein synthesis.

Animals↗

PubMed1982