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Protein synthesis in the tissues of the silkworm, Bombyx mori, infected with nuclear-polyhedrosis virus
NOTES Protein
Synthesis in the Tissues of the Silkworm, Bombyx mot-i, Infected with Nuclear-Polyhedrosis Virus
It has been shown that the application of various labeled amino acids to radioautography is greatly effective for the investigation of protein metabolism in the different tissues of various animals (C. P. Leblond, and K. B. Warren, eds., “The Use of Radioautography in Investigating Protein Synthesis,” Academic Press, New York and London, 1965). The purpose of the study here reported was to survey the synthetic activity of protein in the tissues of the silkworm, Bombyx mori, infected with nuclear-polyhedrosis virus by means of radioautography with a tritiated amino acid as a protein precursor. The virus was administered perorally to fourth-instar larvae by feeding them on mulberry leaves which had been smeared with a high concentration of the virus polyhedra (5 X 10s polyhedra/ml) for 20 hr. The larvae were reared at 25°C throughout the experiment. On the 5th day after inoculation of the virus, each infected larva and each control larva was given a subcutaneous injection of tyrosine-3H (specific activity 185 mc/mM) in the amount of 20 PC/g body weight. At intervals of the 0.5, 1, 3, and 5 hr after injection, body parts, including hypodermis, fat body, muscle, midgut, etc., were sampled from each treated larvae, and then fixed with Carnoy’s fluid, embedded in paraffin, and sectioned at 4 p. Radioautographs of the deparafhnized sections were made with Sakura NRM2 liquid emulsion (Konishiroku, Tokyo) and these were. exposed for 3 weeks. All of them were stained with hematoxylin-eosin through the emulsion. A time-series of radioautographs of the normal as well as the diseased tissues re,428
vealed that at the first time interval (30 min. ) no cells were labeled with tyrosine“H, but at 1 hr the label appeared in almost all of the tissue cells and became more labeled with the successive intervals through 5 hr post-injection (Figs. l-4). Radioautographic preparations of the diseased larva on the 5th day after infection showed that most of the cells in the susceptible tissues, such as hypodermis, tracheal epithelium, and fat body, contained polyhedra in their nuclei but the other cells were at various infection stages before polyhedra formation. The uptake of label by the diseased cells prior to formation of polyhedra, even the cells at “ring zone” stage, did not differ from that by the normal cells. On the other hand, the initial deposition of label was most evident over the polyhedra and with increasing time more and more radioautographic grains were deposited over the growing polyhedra. It may be concluded from these observations that the protein synthetic activity was not appreciably enhanced in the diseased cells up to a point just prior to polyhedra formation, whereafter an active protein synthesis pronouncedly occurred around the newly developed polyhedra and continued with the polyhedral growth. HITOSHI
Laboratory Faculty of University Bunkyo-ku,
of Sericulture Agriculture of Tokyo Tokyo, Japan
Received April 6, 1967
WATANABE
FIGS. 14. Radioautographs demonstrating the incorporation of tyrosine-“H into the diseased silkworm tissues infected with nuclear-polyhedrosis virus. Hematoxylin-eosin stain. Magnification: 590 ><. Thirty minutes after injection of the label (Fig. l), no reaction is seen over all of the cells of tire fat body (f). One hour after injection (Fig. Z), radioactive grains appear over the infected tissues such as hypodermis (h), fat body (f), and tracheal epithelium ( t ), but not over the muscle i m ). In the infected tissues grains are dense over the polyhedra, while the concentration of radioactivity over the infected cell even at “ring zone” stage (r) is generally not different from that of the normal cell. At 3 (Fig. 3) and 5 hr. (Fig. 4) after injection of labeled material, more and more grains appears to deposit around the growing polyhedra. Cellular distriblition of grains also increases slightly in the various tissues.
Synthesis in the Tissues of the Silkworm, Bombyx mot-i, Infected with Nuclear-Polyhedrosis Virus
It has been shown that the application of various labeled amino acids to radioautography is greatly effective for the investigation of protein metabolism in the different tissues of various animals (C. P. Leblond, and K. B. Warren, eds., “The Use of Radioautography in Investigating Protein Synthesis,” Academic Press, New York and London, 1965). The purpose of the study here reported was to survey the synthetic activity of protein in the tissues of the silkworm, Bombyx mori, infected with nuclear-polyhedrosis virus by means of radioautography with a tritiated amino acid as a protein precursor. The virus was administered perorally to fourth-instar larvae by feeding them on mulberry leaves which had been smeared with a high concentration of the virus polyhedra (5 X 10s polyhedra/ml) for 20 hr. The larvae were reared at 25°C throughout the experiment. On the 5th day after inoculation of the virus, each infected larva and each control larva was given a subcutaneous injection of tyrosine-3H (specific activity 185 mc/mM) in the amount of 20 PC/g body weight. At intervals of the 0.5, 1, 3, and 5 hr after injection, body parts, including hypodermis, fat body, muscle, midgut, etc., were sampled from each treated larvae, and then fixed with Carnoy’s fluid, embedded in paraffin, and sectioned at 4 p. Radioautographs of the deparafhnized sections were made with Sakura NRM2 liquid emulsion (Konishiroku, Tokyo) and these were. exposed for 3 weeks. All of them were stained with hematoxylin-eosin through the emulsion. A time-series of radioautographs of the normal as well as the diseased tissues re,428
vealed that at the first time interval (30 min. ) no cells were labeled with tyrosine“H, but at 1 hr the label appeared in almost all of the tissue cells and became more labeled with the successive intervals through 5 hr post-injection (Figs. l-4). Radioautographic preparations of the diseased larva on the 5th day after infection showed that most of the cells in the susceptible tissues, such as hypodermis, tracheal epithelium, and fat body, contained polyhedra in their nuclei but the other cells were at various infection stages before polyhedra formation. The uptake of label by the diseased cells prior to formation of polyhedra, even the cells at “ring zone” stage, did not differ from that by the normal cells. On the other hand, the initial deposition of label was most evident over the polyhedra and with increasing time more and more radioautographic grains were deposited over the growing polyhedra. It may be concluded from these observations that the protein synthetic activity was not appreciably enhanced in the diseased cells up to a point just prior to polyhedra formation, whereafter an active protein synthesis pronouncedly occurred around the newly developed polyhedra and continued with the polyhedral growth. HITOSHI
Laboratory Faculty of University Bunkyo-ku,
of Sericulture Agriculture of Tokyo Tokyo, Japan
Received April 6, 1967
WATANABE
FIGS. 14. Radioautographs demonstrating the incorporation of tyrosine-“H into the diseased silkworm tissues infected with nuclear-polyhedrosis virus. Hematoxylin-eosin stain. Magnification: 590 ><. Thirty minutes after injection of the label (Fig. l), no reaction is seen over all of the cells of tire fat body (f). One hour after injection (Fig. Z), radioactive grains appear over the infected tissues such as hypodermis (h), fat body (f), and tracheal epithelium ( t ), but not over the muscle i m ). In the infected tissues grains are dense over the polyhedra, while the concentration of radioactivity over the infected cell even at “ring zone” stage (r) is generally not different from that of the normal cell. At 3 (Fig. 3) and 5 hr. (Fig. 4) after injection of labeled material, more and more grains appears to deposit around the growing polyhedra. Cellular distriblition of grains also increases slightly in the various tissues.