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F Wilt

Publications and source records attributed to F Wilt.

25 records · Page 2Linked to original sources
PubMed1986

Site and stage specific action of endogenous nuclease and micrococcal nuclease on histone genes of sea urchin embryos.

The early histone genes of sea urchin embryos are expressed exclusively during cleavage stages of embryogenesis. The chromatin containing these genes was examined by nuclease sensitivity. An endogenous nuclease active during cleavage, produces 1300-bp segments containing early histone genes. The cutting sites have been mapped; there are very sensitive sites close to the cap site for H1, H2A, H2B, and H4. Chromatin obtained from embryos of later stages, when the genes are not expressed, do not display this pattern of nuclease sensitivity. Micrococcal nuclease produces nucleosomes that contain histone genes when used with nuclei from later stages, but not with nuclei from cleavage stages.

Animals↗
PubMed1986

The organic matrix of the skeletal spicule of sea urchin embryos.

The micromeres that arise at the fourth cell division in developing sea urchin embryos give rise to primary mesenchyme, which in turn differentiates and produces calcareous endoskeletal spicules. These spicules have been isolated and purified from pluteus larvae by washing in combinations of ionic and nonionic detergents followed by brief exposure to sodium hypochlorite. The spicules may be demineralized and the integral matrix dissolves. The matrix is composed of a limited number of glycoproteins rich in aspx, glux, gly, ser, and ala, a composition not unlike that found in matrix proteins of biomineralized tissues of molluscs, sponges, and arthropods. There is no evidence for collagen as a component of the matrix. The matrix contains N-linked glycoproteins of the complex type. The matrix arises primarily from proteins synthesized from late gastrulation onward, during the time that spicule deposition occurs. The mixture of proteins binds calcium and is an effective immunogen. Electrophoresis of the glycoproteins on SDS-containing acrylamide gels, followed by blotting and immunocytochemical detection, reveals major components of approximately 47, 50, 57, and 64 kD, and several minor components. These same components may be detected with silver staining or fluorography of amino acid-labeled proteins. In addition to providing convenient molecular marker for the study of the development of the micromere lineage, the spicule matrix glycoproteins provide an interesting system for investigations in biomineralization.

Amino Acids↗
PubMed1986

The art of pharmacotherapy in depressed outpatients.

There is an art to prescribing medications to depressed patients. Both patient and therapist factors are important to a successful outcome with appropriate timing and prescribing of treatment. Two case reports are provided as examples. Specific strategies used by experienced clinicians are presented in the discussion.

Adult↗
PubMed1983

Morphology of the organic matrix of the spicule of the sea urchin larva.

The morphology of the organic matrix of the skeletal spicule of the sea urchin pluteus larva has been analyzed by light and electron microscopy. Purified isolated spicules can be demineralized, and they reveal lamellae of an irregular fibrillar nature with overall outlines similar to the shape of the intact spicule. Sections through the spicule show the fibrous lamella is probably composed of interconnected concentric sleeves.

Animals↗
PubMedDate not supplied

Immunogold detection of glycoprotein antigens in sea urchin embryos.

Four developmental stages of sea urchin embryos were labeled with colloidal gold in an attempt to elucidate the intracellular trafficking patterns within the cells that produce the glycoprotein matrix of the embryonic spicule. The primary mesenchyme cells (PMCs) form a syncytium and secrete an organic matrix on which calcium carbonate is laid down to form an endoskeletal spicule. The organic matrix has been isolated and characterized as glycoprotein consisting of four major bands. Polyclonal antibodies to these glycoproteins were used to label embryos from the mesenchyme blastula, early gastrula, late gastrula, and plutei stages of development. The label is concentrated in the Golgi complex and associated vesicles, in secretory vesicles, and in the organic matrix. The density of the labeling increases as development proceeds.

Animals↗