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Biomedical subjects

W F Reynolds

Publications and source records attributed to W F Reynolds.

50 records · Page 3Linked to original sources
PubMed1984

Protamines in plant sperm.

Sperm protamines have been isolated from representatives of three major plant groups: algae (Chara corallina ), bryophytes ( Marchantia polymorpha), and ferns ( Marsilea vestitia ). We previously reported the complete displacement of histones by protamines in Marchantia (Reynolds W F & Wolfe, S L, Exp cell res 116 (1978) 269 [8] ). Marchantia protamines appear as four components on acid-urea gels, whereas Chara and Marsilea protamines comigrate as a single band with a mobility comparable to salmon protamine. The amino acid compositions of the plant protamines show these to be arginine-rich, highly basic (35-42%) proteins which display overall similarity in amino acid composition (84-91%). The molecular weights of Chara and Marsilea protamines are approx. 4700-5300 D.

Amino Acids↗
PubMed1983

Control of 5S RNA transcription in Xenopus somatic cell chromatin: activation with an oocyte extract.

A chromatin fraction enriched for Xenopus 5S RNA genes has been isolated by restriction endonuclease digestion and sucrose gradient velocity sedimentation. Soluble chromatin sedimenting at 70-80S contains approximately 50% of the oocyte-expressed 5S RNA genes and only 1.5-3% of total chromatin DNA; this represents a 15- to 30-fold purification of the 5S genes. Such chromatin isolated from somatic cells (blood and cultured kidney cells) retains the transcriptionally-inactive state of the oocyte-expressed 5S genes. Soluble chromatin from somatic cells prepared by micrococcal nuclease digestion also retains the inactive state of the oocyte-type 5S genes. It is likely that the level of chromatin structure responsible for inactivity of the oocyte genes in somatic cells is the nucleosome or short chains of nucleosomes and not supranucleosomal structures. The oocyte-type genes can be rendered transcriptionally active in somatic cell chromatin either by salt extraction of some chromosomal proteins or by treatment with the ion exchange resin Dowex A50W-X2. Alternatively, activation of these genes can be achieved by incubating somatic cell chromatin or nuclei with an extract prepared from Xenopus oocytes. This effect is not specific for 5S RNA genes as the transcription of other small RNAs (including pre-tRNA) is stimulated by the oocyte extract. The activating factor(s) is resistant to micrococcal nuclease, nondialyzable, heat labile and sensitive to trypsin; thus it is highly likely to be a protein or a group of proteins. Partial purification of the activating factor(s) has been achieved by ion exchange chromatography.

Animals↗
PubMed1983

5S rRNA gene transcription factor IIIA alters the helical configuration of DNA.

Relaxation of Xenopus 5S plasmid DNA (pX1o8) in the presence of transcription factor (TF) IIIA reduces the linking number of the DNA. Parallel experiments with plasmid pMB9 or cloned hepatitis B viral DNA indicate a degree of non-specific unwinding by TF; however, 60% of the effect observed for pX1o8 is due to specific interaction of TF IIIA with the 5S rRNA gene internal promoter sequence. The extent of unwinding (0.2-0.4 helical turn per TF IIIA binding site) is not consistent with the complete denaturation of the 50-base-pair TF binding site; however, it is consistent with a change in helix rotation, denaturation of 2-4 nucleotides per binding site, or DNA wrapping about a protein core. We show that proteins other than TF IIIA (bovine serum albumin and RNase) have no effect on the linking number of DNA when present during relaxation and that the unwinding activity associated with TF is heat labile. These results suggest that TF IIIA may facilitate transcription by altering the helical configuration of 5S DNA.

Animals↗
PubMed1978

Uncommon radiologic observations in renal milk-of-calcium stone.

Milk-of-calcium stone is a rare finding in the kidney. It is diagnosed radiologically based on the fact that the opacity takes a semilunar shape and layers according to the position of the patient. An unusual observations is that layering may require some time to take place and that the semilunar configuration may be found incidentally in the supine position as well.

Adult↗
PubMed1977

Diagnostic problems of epithelial tumors of penis.

Malignant epithelial tumors of the penis often present aspects which make difficult an accurate clinical and pathologic diagnosis. Frequently, repeated biopsies yield a benign diagnosis while the tumor continues to progress and sections through it indicate malignant components. It is suggested that epithelial tumors of the penis may consist, in many instances from their start, of a mixture of benign and malignant elements in ratios varying from one extreme to the other. This may explain why biopsies are frequently misleading, yielding a benign result while, in fact, the tumor is malignant.

Aged↗
PubMed1977

Seeding mechanism of urothelium over nonepithelialized surfaces.

To study urothelial spreading over nonepithelialized tissue surfaces, bladder defects in rabbits were patched with pedicled prevesical fat. Using serial sections and scanning electron microscopic studies, it was concluded that urothelium in the process of covering nonepithelialized surfaces is able to seed at a distance from the periphery of the defect as one means of epithelializing a defect.

Adipose Tissue↗
PubMed1977

Determination of the preferred tautomeric form histamine by 13C nmr spectroscopy.

The pH-dependent 13C chemical shifts for histamine indicate an approximate 4: 1 preference for the N-H tautomer of the imidazole ring, similar to that previously deduced for L-histidine. It is concluded that the 13C chemical shift method is a complimentary technique to the method of determining tautomer preference from pK values. Factors determining the tautomer preference in histamine and L-histidine are discussed.

Histamine↗