In situ demonstration of DNA hybridizing with chromosomal and nuclear sap RNA in Chironomus tentans

Cytological hybridization combined with microdissection of Chironomus tentans salivary gland cells was used to locate DNA complementary to newly synthesized RNA from chromosomes and nuclear sap and from a single chromosomal puff, the Balbiani ring 2 (BR 2). Salivary glands were incubated with tritiated nucleosides. The labeled RNA was extracted from microdissected nuclei and hybridized to denatured squash preparations of salivary gland cells under conditions which primarily allow repeated sequences to interact. The bound RNA, resistant to ribonuclease treatment, was detected radioautographically. It was found that BR 2 RNA hybridizes specifically with the BR 2 region of chromosome IV. Nuclear sap RNA was fractionated into high and low molecular-weight RNA; the former hybridizes with the BR 2 region of chromosome IV, the latter in a diffuse distribution over the whole chromosome set. RNA from chromosome I hybridizes diffusely with all chromosomes. Nucleolar RNA hybridizes specifically with the nucleolar organizers, contained in chromosomes II and III. It is concluded that the BR 2 region of chromosome IV contains repeated DNA sequences and that nuclear sap contains BR 2 RNA.

Interrelationship between rat serum very low density and high density lipoproteins

An exchange of phospholipids and certain peptides among various classes of rat serum lipoproteins has been demonstrated and its nature has been investigated. [(32)P]-Phospholipid from isolated VLDL, prepared in vivo, was transferred to HDL, and to a much lesser extent to LDL, in vivo and in vitro. This difference between HDL and LDL can be abolished by ultracentrifugation of the serum at d 1.21. Unlabeled VLDL acquired [(32)P]phospholipid from HDL of serum. Phospholipid associated with the alpha-lipoprotein component of VLDL exchanged more readily than that associated with the beta-lipoprotein component of VLDL. Generally, the phospholipid species exchange in proportion to their distribution in the lipoproteins. Radioactivity from (3)H-labeled protein of VLDL was transferred to HDL while HDL (3)H-labeled protein in serum was transferred to VLDL during a 20-min incubation. LDL was not involved in the transfer of protein. Protein associated with the alpha-lipoprotein component of VLDL exchanged more readily than that associated with beta-lipoprotein component. Analysis of tritiated apoproteins of VLDL and HDL by polyacrylamide gel electrophoresis revealed that three of the six peptide bands of apo-VLDL exchanged between VLDL and HDL. The data raise the possibility that intact subunits of the VLDL and HDL are being exchanged.

The immunological and physicochemical properties of mitogenic proteins derived from Phaseolus vulgaris

A commercially available phytohaemagglutinin derived from Phaseolus vulgaris (PHAP) was subjected to CM Sephadex and Sephadex G-150 chromatography. Two major mitogenic fractions were isolated; one (L-PHAP), appeared homogeneous by polyacrylamide gel electrophoresis, and was virtually lacking in haemagglutinating activity, while the other (H-PHAP) was a potent haemagglutinin. H-PHAP was a complex material as shown by its behaviour on CM Sephadex chromatography. Electrophoretic analysis revealed three distinct bands of protein, all migrating cathodally to L-PHAP. With increasing cathodal mobility H-PHAP subfractions showed diminishing mitogenicity, increasing haemagglutinating potency, and the appearance of the ability to precipitate serum proteins non-specifically. The latter property, present in crude PHAP, was not displayed by L-PHAP. The mitogenic activity of all H-PHAP subfractions was potentiated by the presence of autologous red blood cells.

While L- and H-PHAP were closely related by immunological criteria, distinct differences were noted by three methods of analysis. The most cathodal of the H-PHAP subfractions was found to be immunodeficient by comparison with crude PHAP, L-PHAP, and the remaining H-PHAP subfractions. The implications of these findings with respect to the biological activity of PHAP and to its subunit structure are discussed.

A brain protein unique to the olfactory bulb

Soluble extracts from several regions of the mouse brain manifested regionally specific protein band patterns on polyacrylamide gel electrophoresis. In particular, one protein band appeared to occur uniquely in the olfactory bulb extracts where it was a quantitatively significant constituent of the soluble protein extract. This protein was purified to homogeneity by ammonium sulfate precipitation, DEAE-cellulose column chromatography, and polyacrylamide gel electrophoresis. The purified protein has a minimum molecular weight of about 20,000 by gel electrophoresis in the presence of sodium dodecyl sulfate. Precipitating antiserum prepared against this protein reacted only with the purified protein or with extracts of olfactory bulb, and not with extracts of other mouse tissues or brain regions. Quantitative immunoprecipitation assays indicate that this specific protein represents 1% of the total soluble protein in the mouse olfactory bulb. Soluble extracts of olfactory bulbs from several rodent species gave reactions of identity by agar gel diffusion with the antiserum to the mouse protein. It is suggested that this protein is an example of selective genetic expression within the central nervous system.

Development of chicken lymphoid system. I. Synthesis and secretion of immunoglobulins by chicken lymphoid cells

Synthesis and secretion of Ig by chicken lymphoid cells was studied. Both spleen and bursa cells synthesize and secrete IgM and IgG whereas Ig was not detected in thymus cells. In contrast to the spleen cells which synthesize H and L chains in balanced quantities, the bursa cells synthesize and secrete free L chains. In addition to the lymphoid cells which secrete IgM or IgG, the bursa appears to contain a cell population which synthesizes nonsecretory Ig. The structure of this Ig was studied by specific serological precipitation and by SDS-acrylamide gel electrophoresis. The H chains of this nonsecretory Ig are serologically related to micro-chains and exhibit a smaller molecular weight (i.e., approximately 50,000) in SDS-acrylamide gel electrophoresis than H chains of IgG and IgM synthesized by the spleen cells (i.e., approximately 70,000).

Hyperlipoproteinemia in fasting ponies

Ponies fasted for up to 8 days showed, both by agarose electrophoresis and preparative ultracentrifugation, the appearance of a pre-beta-migrating, very low density lipoprotein fraction in plasma. This lipoprotein differs from the very low density lipoprotein found in humans and rats in that it contains a relatively smaller amount of total cholesterol, 85% of which is present in the unesterified form. By the 8th day of fasting, plasma triglyceride concentrations had increased from a prefasting level of 20 mg/dl to as high as 1000 mg/dl. The increase in plasma lipid concentrations as a result of fasting was highly variable. Accumulation of plasma cholesterol and triglyceride after injection of Triton WR 1339 was not related to the degree of fasting hyperlipidemia. This suggests that the hyperlipoproteinemia of fasting may result from an impaired utilization of very low density lipoproteins.

Solubilization of envelopes of HVJ (Sendai virus) with alkali-emasol treatment and reassembly of envelope particles with removal of the detergent

The envelopes of HVJ (Sendai virus) virions were solubilized with alkali-Emasol treatment. The solubilized envelope subunit(s) associated with hemagglutination-inhibiting antibody blocking, neuraminidase, and low hemagglutinating (HA) activities had a sedimentation coefficient of 8.8S. Envelope fragment-like structures were assembled from the solubilized subunits after Emasol was removed by gel filtration. These reassembled envelope particles with HA activity had cell-fusion activity as well as hemolytic activity. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the reassembled particles revealed that they mainly consisted of two kinds of polypeptides.

Glutamate dehydrogenase from Mycoplasma laidlawii

Mycoplasma laidlawii possesses a single glutamate dehydrogenase (GDH) with dual coenzyme specificity [specificity for nicotinamide adenine dinucleotide (H) and nicotinamide adenine dinucleotide phosphate (H)]. A purification procedure is reported which results in an enzyme preparation with a specific activity of 79.5 units/mg and which displays only one significant protein band after gel electrophoresis. This one band was determined, by activity staining, to have all of the GDH nucleotide specificities. The molecular weight of the enzyme is 250,000 +/- 10%, and it has a subunit size of about 48,000. The enzyme exhibits measurable activity with aspartate and pyruvate but is inactive with eight other possible substrates. Purine nucleotides do not affect the activity. The K(m) for reduced nicotinamide adenine dinucleotide was 1.8 x 10(-4)m. The optimal substrate concentrations and pH optimum for each of the respective GDH activities are also reported.

Isolation of mycoplasma membranes by digitonin

The cell membrane of Mycoplasma hominis was isolated by lysing the cells with digitonin. Electron microscopy and chemical, density gradient, and electrophoretic analyses of the membrane proteins showed the membranes so obtained, like those isolated by osmotic lysis, to be relatively free of cytoplasmic contaminants. Sensitivity to digitonin lysis depended on temperature but was not affected by Mg(2+) ions and was only slightly affected by the age of the culture. Accordingly, it seems that digitonin may be used for the isolation of cell membranes from sterol-requiring mycoplasmas that tend to be fairly resistant to osmotic lysis.

Purification and properties of mycoferritin from Mortierella alpina

A culture of Mortierella alpina Peyroud isolated from soil and grown on Czapek-Dox medium was found to contain a high concentration of mycoferritin (MF). The MF was extracted from lyophilized mycelium by grinding with 0.1 M, pH 7.0, potassium-phosphate buffer and chloroform followed by differential centrifugation. Sucrose density-gradient centrifugation of the concentrated MF resulted in a brownish-yellow band in the region of 60–70 S. Following dialysis and concentration by high-speed centrifugation, the MF was compared to horse-spleen ferritin (HF). The ultraviolet (uv.) and infrared (i.r.) spectra of MF and HF were identical. Negatively stained preparations examined in the electron microscope showed particles of about 10 nm diameter. Sedimentation rates of S20,w = 66 for MF and S20,w = 56 for HF were obtained by analytical ultracentrifugation. The MF preparation contained 83% protein and 17% iron. The molecular weight of the protein subunit was determined by gel electrophoresis to be about 19 300 daltons.