520 G. H. BERGOLD 



yields of amino acids (on a nitrogen and a weight basis) and the total N 

 content, one can conclude that the vims membranes consist of about 80 % 

 and the virus of about 85 % nitrogenous compoimds. About 1.3 and 0.2 % 

 lipids can be extracted with boiling petrol ether from virus membranes and 

 from the virus particles respectively, and a maximum of 7.5 % with a 

 mixture of chloroform and methanol (4 : 1, 1 lir. at 50-55°C., and overnight 

 at 20° C.) from the virus particles. About half of the 7.5 % extractable ma- 

 terial of the virus can be accounted for by paper chromatography as total 

 hpids. With the anthrone reaction about 1.2 % carbohydrates were fomid in 

 the virus. Considering aU the analyses, one can calculate that about 9 % of 

 the weight of the virus and an even higher percentage of the virus membranes 

 are stUl unaccounted for. It is not likely that much water was retained in the 

 virus because it was dried over P20^ for about one week in high vacuum at 

 room temperature and under the same conditions for 4 hr. at 110°C. (Ber- 

 gold, 1957). 



Gershenson (1956b, c) isolated protein-free DNA with Na CI and DNA- 

 free protein from A. jperyni polyhedra. Neither preparation was infectious 

 when injected singly or in succession into A. peryni pupae. However, when 

 the DNA and protein preparations were mixed and left together for 7 hr. 

 (4 hr. at 4° C. and 3 hr. at room temperature) before injection, 40 % died of 

 polyhedrosis when about 1 mg. DNA aud 5 mg. protein per pupa was used. 

 Bergold (1958a,b) isolated DNA from purified B. mori particles usiiig para- 

 amino sahcylate and phenol. The DNA preparation was very viscous ; 

 it had an /Sao of about 14.5 Svedberg, but contained some protein which, 

 however, was serologically not related to virus protein. The infectivity of 

 this DNA preparation (10~^ gni./5. mori larvae) was only 0.0001 % of that 

 of the same amount of untreated DNA still contained in the intact virus 

 particle. 



In a search for the presence of enzymes in insect virus particles, a catalase 

 was reported from alkaline solutions of B. mori polyhedra, which was more 

 active at pH 8.9 than at pH 7.6 (Yamafuji et al., 1941) as well as a proteinase 

 (Yamafuji et al., 1957). However, in other investigations no peptidase 

 or phosphatase could be found (Duspiva and Bergold, 1942), and no lipase, 

 lecithinase, hexosediphosphatase, nuclease, amylase, carboxylase, phenyl- 

 oxidase, dehydrogenase, catalase, or protease could be detected in poly- 

 hedron solutions (Kuzin and Krzhevova, 1948). A deoxyribonuclease. was 

 recently reported to be present in an akaline solution of B. mori polyhedra 

 (Yamafuji, 1956; Yamafuji et al., 1957). However, a reinvestigation in which 

 the enzyme was assayed by measuring the release of trichloroacetic acid- 

 soluble nucleotides revealed that no significant amounts of deoxyribonuclease 

 are present in suspensions of polyhedra, polyhedron solutions, and purified 

 vnrus particles (Faidkner and Bergold, 1957). 



