Using a subtractive cDNA cloning method, we isolated a number of T-lymphocyte-specific genes. One of these genes, represented by the cDNA clone pT49, is expressed in cytotoxic T lymphocytes but not in helper T lymphocytes or B lymphocytes. The protein structure deduced from the nucleotide sequence showed a high degree of homology to fibrinogen 13 and y subunits. This might indicate that evolutionarily fibrinogen has its origin in lymphocytes. In spite of the strong homology of pT49 protein to the fibrinogen subunits, the positions of the introns in the pT49 gene are totally different from those of the fibrinogen genes.

The accompanying paper (S. Kawai and T. Koyama, J. Virol. 51:147-153, 1984) describes the isolation and biological properties of a mutant, TK15, derived from a Rous sarcoma virus mutant, tsNY68. The cisacting defect of the mutant is analyzed biochemically in this paper. TK15 virions released from virus-producing 15c(+) cells were deficient in viral genomic 39S RNA, although comparable amounts of viral RNAs were transcribed in 15c(+) and tsNY68-infected cells. Analysis of provirus DNA occurring in 15c(+) cells suggested that the mutant genome had a deletion of ca. 250 bases near the 5' end of the genome somewhere between the primer binding site and the 5' end of the gag-coding region. These findings indicate that at least part of the sequence lost in the TK15 genome is indispensable for packaging viral genomic RNA into virions. TK15 induces nonvirus-producing 15c(-) transformants at high frequency. Southern blot analysis of DNAs from those 15c(-) clone cells revealed that TK15-derived proviruses contained various extents of internal deletions. Many 15c(-) clones had a provirus carrying only the src gene with long terminal repeat sequences at both ends. The mechanism for the segregation of 15c(-) cells is discussed.

Staphylococcus aureus, which usually forms grape-like clusters, has the ability to form regularly arranged cell packets. These regular cell packets are formed when the activity of its separation enzyme(s) is lost either by treatment with detergents, such as sodium dodecyl sulfate or Trition X-100, or by mutation of the cells. These cell packets consisted of 8 to 64 spherical cells that have a three-dimensional arrangement. Some irregularity in the arragement of cells in packets, however, can be observed by scanning electron microscopy. It is concluded that S. aureus fundametally divides along three definitely oriented planes that are located at right angles to each other. After cell division, the cells usually become translocated due to the action of a separation enzyme(s) to form grape-like clusters.

A mutant derived from a temperature-sensitive mutant of Rous saromca virus (tsNY68) which showed extremely low infectivity was characterized. Infection of chicken embryo fibroblast cells with the mutant, TK15, induced two types of transformants, mutant-producing 15c(+) and nonvirus-producing 15c(-) transformants. 15c(+) cells expressed all four viral genes normally and produced a normal level of virus particles. No complementation was observed between the mutant and avian leukosis viruses. However, when 15c(+) cells were cocultured with nonvirus-producing cells transformed by Y73, a replication-defective avian sarcoma virus, a high titer of Y73 virus was recovered. From its biological properties, the mutant seemed to have a defect(s) outside the viral genes. Biochemical analysis of the TK15 mutant (T. Koyama, F. Harada, and S. Kawai, J. Virol. 51:154-162, 1984) revealed that it had a defect in packaging its own genomic RNA. During replication of TK15 virus, the TK15 mutant appeared to segregate at high frequency more defective variants that induced 15c(-) transformants, in most of which only the src gene was expressed. The mechanism for the segregation of 15c(-) transformants is discussed with respect to the defect of the mutant.

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