PubMed Health⌕ Search

Biomedical subjects

S Spiker

Publications and source records attributed to S Spiker.

At least 37 records · Page 2Linked to original sources
PubMed1990

A vertical submarine electrophoresis apparatus for polyacrylamide minigels.

A vertical submarine electrophoresis apparatus for use with minislab polyacrylamide gels is described. The design allows polyacrylamide gels to be run with the same ease and convenience that agarose gels are run with horizontal submarine apparatuses. The vertical submarine features a single buffer chamber with a restriction between the upper and the lower portions of the chamber. Acrylamide gels, cast between 9 X 10-cm glass slides, are inserted into the restriction and are completely immersed in buffer. Thus, current flows primarily through the gel itself, but some current flows through the buffer in the restriction surrounding the gel. Because water-tight separation of buffer chambers is not necessary, time-consuming and/or expensive procedures such as sealing with agarose or using fragile notched glass plates are eliminated. The apparatus can be set up to run a gel in less than 30 s. It is versatile in that gels of varying thickness (0.5, 0.8, 1.5, and 3 mm) can be run on a single apparatus. The apparatus has been used for sodium dodecyl sulfate gels, low ionic strength native gels for nucleoprotein complexes, and composite acrylamide-agarose gels.

Chemistry Techniques, Analytical↗
PubMed1987

Synthesis of nucleosomal histone variants during wheat grain development.

The synthesis and distribution of histone subfractions (variants) were investigated during early grain development and in mature tissues of wheat (Tritium aestivum L.). Histones were extracted from purified chromatin and separated by two-dimensional polyacrylamide gel electrophoresis. There were no detectable differences in the patterns of histone variants from immature grain (3-16 days after fertilization), from mature embryos, from coleoptiles and roots of 4-day-old, etiolated seedlings and from leaves of 10-day-old, light-grown seedlings. Wheat H2 histones are composed of families of closely related variants. H2A consists of three major variants, and H2B consists of two major and four minor variants. The synthesis of these variants during early grain formation was determined by calculating the specific activities of the [3H]lysine-labeled proteins synthesized between 3 and 10 days after fertilization. The rate of synthesis of the nucleosomal histones closely parallels the declining rate of cell division in developing grains. Our results indicate that all the recognized wheat histone variants are present in developing wheat grains from the earliest time investigated (3 days after fertilization) and persist with no detectable changes in relative quantities throughout grain development and in several mature tissues.

Genetic Variation↗
PubMed1987

Fractionation of plant and animal high mobility group chromosomal proteins by ion-exchange and reversed-phase high-performance liquid chromatography.

A method for purifying wheat high mobility group (HMG) chromosomal proteins using a combination of weak cation-exchange and reversed-phase high-performance liquid chromatography (HPLC) is described. Previously reported HPLC systems devised for fractionating HMG proteins of vertebrate animals are not effective for the plant proteins. The system described here can be used for the fractionation of both plant and animal HMG proteins.

Animals↗
PubMed1984

High-mobility group chromosomal proteins of wheat.

Four proteins have been extracted from purified chromatin of wheat embryos with 0.35 M NaCl. These proteins are soluble in 2% (w/v) trichloroacetic acid and thus meet the original operational requirements to be classified as "high-mobility group" (HMG) chromosomal proteins. The proteins have been characterized by one- and two-dimensional electrophoresis, amino acid analysis, and peptide mapping. Three of the proteins (HMGb, c, and d) share the mammalian HMG characteristic of being rich in both acidic and basic amino acid residues. Unlike their putative mammalian counterparts, these plant HMG proteins contain less than 7 mol % proline. The fourth wheat protein (HMGa) is rich in both proline and in basic amino acid residues. This wheat protein, however, contains only about half the proportion of acidic residues found in mammalian HMG proteins--a characteristic also found in the trout testis HMG protein, H6. Comparative peptide maps show that none of the wheat HMG proteins are degradation products of other HMG proteins or the H1 histones. The peptide maps have not, however, been useful in establishing homologies with mammalian HMG proteins. Wheat HMG proteins are released from DNase I-treated nuclei and co-isolate with micrococcal nuclease-sensitive chromatin fractions. Similar observations concerning the HMG proteins of vertebrate animals have been considered consistent with a role for these proteins as structural components of actively transcribed chromatin.

Amino Acids↗
PubMed1983

DNase I sensitivity of transcriptionally active genes in intact nuclei and isolated chromatin of plants.

We have investigated the DNase I sensitivity of transcriptionally active DNA sequences in intact nuclei and isolated chromatin from embryos of wheat (Triticum aestivum L.). Nuclei or isolated chromatin was incubated with DNase I, and the extent of DNA digestion was monitored as percentage acid solubility. The resistant DNA and DNA from sham-digested controls were used to drive reassociation reactions with cDNA populations corresponding to either total poly(A)+RNA from unimbibed wheat embryos or polysomal poly(A)+RNA from embryos that had imbibed for 3 hr. Sequences complementary to either probe were depleted in DNase I-resistant DNA from nuclei and from chromatin isolated under low-ionic-strength conditions. This indicates that transcriptionally active sequences are preferentially DNase I sensitive in plants. In chromatin isolated at higher ionic strength, cDNA complementary sequences were not preferentially depleted by DNase I treatment. Therefore, the chromatin structure that confers preferential DNase I sensitivity to transcriptionally active genes appears to be lost when the higher-ionic-strength method of preparation is used. Treatment of wheat nuclei with DNase I causes the release of four prominent nonhistone chromosomal proteins that comigrate with wheat high mobility group proteins on NaDodSO4 gels.

Cell Nucleus↗
PubMed1982

Histone variants in plants. Evidence for primary structure variants differing in molecular weight.

Variants of H2a and H2b histones from wheat embryos and pea shoots have been isolated and characterized by two-dimensional gel electrophoresis, amino acid content, and peptide mapping. In striking contrast to the animal H2a or H2b variants which co-migrate on sodium dodecyl sulfate polyacrylamide gels, their plant counterparts have differential electrophoretic mobilities. The estimated molecular weights of the wheat H2a variants range from 16,600 to 19,000. The H2b variants range from 15,300 to 19,000. Correlating with their electrophoretic mobilities, the plant histone variants elute differentially from gel exclusion columns in a manner consistent with the molecular weight differences inferred from the sodium dodecyl sulfate gels. The differences in peptide maps of the wheat H2a variants are extensive and indicate amino acid substitutions throughout the molecules. The maps of the plant H2a histones are also distinct from those of the major calf thymus H2a histones. The peptide maps of the plant H2b variants are very similar to each other but are markedly different from those of calf thymus H2b histones.

Amino Acid Sequence↗
PubMed1977

Cross-complexing pattern of plant histones.

Pea histones H2a, H2b, H3, and H4 have been isolated and their interactions studied by fluorescence anisotropy, light scatter, and circular dichroism. Histones H3 and H4 are almost identical in plants and animals, but plant histones H2a and H2b differ markedly from their mammalian counterparts. Pea H2b has a molecular weight approximately 20% greater than that of calf thymus H2b; the amino acid compositions of the two proteins are different. Calf thymus H2a exists as a single molecular weight species, while pea H2a exists as two species which differ by about 1500 daltons. The larger plant H2a is about 19% greater in molecular weight than calf thymus H2a. The smaller is about 8% greater. Despite these differences between calf and pea histones, the strong interactions between histone pairs H3 and H4, H2b and H4, and H2a and H2b, previously demonstrated for calf histones, also exist for pea histones. There are also weak interactions between pea H2a and H4 and between pea H2b and H3, and an interaction of intermediate strength between H2a and H3. The cross-complexing pattern of the plant histones is therefore the same as that reported for calf thymus histones [D'Anna, J. A., Jr., and Isenberg, I. (1974), Biochemistry 13, 4992], despite the dissimilarities of H2a and H2b.

Amino Acids↗
PubMed1975

An evolutionary comparison of plant histones.

Histones were extracted from chromatin of the following: a moss (Polytrichum juniperinum); the primitive vascular plants Psilotum nudum and Equisetum arvense; a fern (Polypodium vulgare); the gymnosperms fir (Abies concolor), yew (Taxus canadensis) and Gingko biloba; the dicotyledonous angiosperms tobacco (Nicotiana tabacum) and maple (Acer saccharinum); and the monocotyledonous angiosperms corn (Zea mays) and lily (Lilium longiflorum). The histones were subjected to polyacrylamide gel electrophoresis and compared to standard histones of pea (Pisum sativum) and cow (Bos taurus). All species have histones of the exact electrophoretic mobility of histones F2a1 and F3 of cow and pea. All species have histones of low electrophoretic mobility assumed to be F1 histones. None of the plant histones displayed electrophoretic mobility between F3 and F2a1 while animal histone fractions F2b and F2a2 do migrate to this position. No animal histone fraction was found to migrate between F3 and F1 while a major plant fraction, designated "F2b-like" was found to migrate to this position in all plant species studied except for the moss and Psilotum. A band of similar mobility was strikingly absent from the histones of these two species.

Biological Evolution↗
PubMed1972

A modified procedure for fractionating histones.

A method is described, which is capable of fractionating histones obtained from any animal source into five major groups. Although the method is based on procedures initially developed by E. W. Johns (1964), involving differential solubility in solutions of acids and of ethanol, it gives a cleaner separation and possesses the considerable advantage that the starting material is whole histone rather than a nucleoprotein preparation.

Animals↗