Transduction of the cellular src gene and 3'' adjacent sequences in avian sarcoma virus PR2257.

When injected into chickens, a transformation-defective mutant of the Prague C strain of Rous sarcoma virus induced tumors at low incidence and after a long latency. One such tumor released a replication-defective virus designated PR2257. We molecularly cloned and sequenced the proviral DNA from quail fibroblasts transformed by PR2257. Comparison of PR2257 sequence with that of Prague C, cellular src, and 3' adjacent cellular DNA showed that the spliced version of the c-src gene and about 950 base pairs (bp) of 3'-flanking cellular DNA were transduced into PR2257. This transduction eliminated nearly all replicative genes, since the gag gene splice donor site was linked to the splice acceptor site of the src gene and, on the 3' side, recombination occurred in the end of env gene. Insertion of two extra cytosines 23 bp before and 19 bp after the c-src stop codon resulted in an extension of the coding portion up to 587 amino acids, divergence of sequences after Pro-525 and replacement of Tyr-527 by a valine residue. In addition, it appears that the 5' and 3' untranslated regions of PR2257 result from multiple recombinations between exogenous and endogenous virus genomes. Limited digestion of p66src encoded by PR2257 with Staphylococcus aureus V8 protease yielded a V2 peptide (C-terminal moiety) with an apparent molecular mass of 31 kilodaltons, consistent with the 5.7-kilodalton increase expected from the DNA sequence. The structure of PR2257 suggests that the first step in the capture of c-src gene by avian lymphomatosis viruses is the trans splicing of the viral leader mRNA to exon 1 of c-src.     

Tumor induction by the LTR,v-src,LTR DNA in four B (MHC) congenic lines of chickens

We report that the cloned DNA harboring the long terminal repeat (LTR), v-src, LTR proviral structure is tumorigenic in chickens of the Prague congenic lines. The growth rate of these tumors is by far the highest in the recombinant CC.R1 line, the B haplotype of which is composed of the B-F/L ⁴ and B-G ¹² subregions originating from different naturally occurring haplotypes. Some of the tumors induced by the LTR, v-src, LTR DNA are repeatedly transplantable in syngeneic chickens, maintain unaltered provirus, and express v-src mRNA. Differences in the response to challenge with Rous sarcoma virus (RSV) and LTR, v-src, LTR DNA on a given experimental model are compared and possible involvement of an interaction between B-F/L and B-G region gene is considered. Regression of the LTR, v-src, LTR DNA-induced tumors did not prevent the formation and growth of tumors induced subsequently by RSV.     

Effect of sulfur-containing agrochemicals on growth,yield, and protein content of soybeans (Glycine max (L.) Merr)

In this study, effect of different forms of sulfur-containing agrochemicals on growth, yield, and protein content of soybean grains have been evaluated. Three forms were used, such as powdery, solute, and pasty, in which elemental sulfur is contained in a nanostructured state. Plants treated with powdered and solute sulfur-containing agrochemicals had the highest growth and grain yield values, and the effect of applying pasty sulfur-containing agrochemicals did not differ from the control, in which there was low yield on all variants. The use of powdered and solute sulfur-containing agrochemicals increased all protein fractions in soybeans. The results show that the use of powdered and solute sulfur-containing agrochemicals is necessary to boost the yield of soy and increase the supply of proteins in the grains. A key factor in the availability of sulfur for soybean plants is the conversion of sulfur to a nanodisperse state. This study provides relevant information about sulfur-containing agrochemicals, which can promote higher seed yields and increase the content of protein in soybeans.