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The distribution patterns of RNA coliphages (phages) in Senegal, Ghana, and Madagascar were investigated by collecting sewage samples from domestic drainage in November, 1980. In Senegal, among 65 sewage samples collected mainly from Dakar and its vicinity, 14 (22%) contained RNA phages (16 strains). By serological analysis, 13 of the 16 strains were found to belong to group III. This is consistent with the distribution pattern of RNA coliphages in tropical and subtropical regions of Asia. In Ghana, however, among 106 samples collected from Accra, Suhum, and their vicinities, only seven (7%) contained RNA phages (seven strains) (groups I, II, and III [1:3: 3]). In Madagascar, among 124 samples collected from Antananarivo, Moramanga, and their vicinities, seven (6%) contained RNA phages (seven strains) (groups I, II, III, and IV [1:1:1:4]). In spite of the low isolation frequency, it can be said that Madagascar appears to have a unique distribution pattern (abundance of group IV phages) which differs from that of any other countries we have examined. The generality of the distribution pattern of RNA phages in the tropical region (abundance of group III phages) was thus verified at least in Senegal.

Conclusion: The present study suggests that Ki-raspoint mutations may play an important role in the early stages of tumorigenesis and that a double mutation has a stronger detrimental effect than a single mutation on the survival after pancreatectomy. Background: Previous studies have suggested the important role of Ki-raspoint mutations inrasgene codon 12 in the tumorigenesis of pancreatic cancer, but their clinicopathological significance is still unclear. The present study was designed to assess the clinicopathological significance of Ki-raspoint mutations, and p21 expression in malignant and benign diseases of the pancreas. Methods: Oligonucleotide dot-blot hybridization for Ki-raspoint mutations in codon 12 and immunohistochemical staining for p21 expression were applied. Cases included 44 primary and 15 metastatic lesions of pancreatic cancer, and 17 benign pancreatic diseases. Results: Ki-raspoint mutations and p21 expression were detected in 43 and 19 primary lesions, 9 and 6 metastatic lesions, and four and five benign diseases, respectively. The patients with a single mutation had a better survival after pancreatectomy than those with a double mutation. The patients with a p21(+) GAT mutation showed the worst survival after pancreatectomy compared with other categories of patients.

Phage FIC is a spontaneous host‐dependent mutant of phage FI which is classified into the fourth group of RNA Escherichia coliphages (RNA coliphages). The mutant phage (FIC) grows normally in E. colistrain Q13 (permissive host), but poorly in strain A/λ (non‐permissive host) (9). Attempts to elucidate the regulatory mechanism of growth of the mutant phage in the non‐permissive host revealed the following: (a) growth of the mutant phage was specifically restricted in E. colistrains that have certain suppressor genes for amber mutation; (b) the mutant phage RNA (FIC‐RNA) could not produce progeny in the spheroplasts of the non‐permissive host; (c) adsorption of the mutant phage to, and penetration of the mutant phage RNA into, the non‐permissive host were normal; and (d) biosynthesis of the phage‐specific late protein and RNA did not occur in the non‐permissive host. Based on these results we conclude that phage FIC is a spontaneous azure‐type mutant of the fourth group of RNA coliphage FI.

We isolated fairly stable lysogenic‐like bacteria from a lysogenic state established between an amber mutant for the maturation protein gene of RNA phage Qβ (Qβam205) and its nonpermissive host BE110. These bacteria contained few mature phages intracellularly (less than 10−3plaque forming unit per cell), continued to grow with a potentiality to produce Qβam205 spontaneously, and showed an immunity‐like response against homologous phage infection. These characteristics were maintained by growth in liquid medium containing anti‐Qβ serum. We designated these cells as pseudolysogenic bacteria. The relative amounts of RNA genomes in these pseudolysogenic cells (about 102infectious RNA strands per cell) indicated that the RNA genomes could replicate in nonpermissive cells and be distributed in daughter cells synchronizing well with cell division.

In order to demonstrate the stability and continuity of RNA coliphages (phages) in their natural habitats, we investigated the amount and group types of RNA phages in sewage samples collected continuously from domestic drainage in Japan proper and islands in the seas adjacent to Japan (abbreviated simply as islands, hereafter) over a 5‐yr period from 1973 to 1977. It was found that the frequencies of isolation of RNA phages were fairly high and constant. The group types of RNA phages isolated were also stable in the three cities, Choshi, Niigata, and Toyama in Japan proper. The average for the three cities was group II: III = 3: 1. The investigation in islands revealed that the frequencies of isolation of RNA phages were fairly high as in the case of the above three cities in Japan proper and the group types of RNA phages isolated were also stable. That is to say, group II phages were predominant on Rishiri Island, Rebun I., Iki I., and Tsushima I., which are located relatively near to mainland Japan, while group III phages were predominant on Amamiohshima I., mainland Okinawa, Ishigakijima I., and Iriomotejima I., which are located south of Kyushu. It can thus be said that the RNA phages in the domestic drainage of Japan proper and islands remained more or less stable over at least the 5‐yr period, and an apparent difference in the geographical distribution of RNA phages in Japan exists between Kyushu and Amamiohshima I.

Starting from the group II RNA phage GA which has an amber mutation in the maturation protein cistron, a spontaneous mutant of group II phage GA, whose serological and electrophoretic properties became similar to those of group I phage MS2, was isolated and analyzed. The mutant has now become sensitive to anti‐MS2 serum and resistant to anti‐GA serum. Analysis of the nucleotide sequence of the coat protein gene revealed that G↔A transition was the main change. The deduced amino acid sequence showed that five amino acids were substituted in the mutant, and three of the five became identical to MS2, resulting in increased molecular weight of the coat protein. However, it did not complement MS2. These results suggested that the serological change from group II phage GA type to group I phage MS2 type is induced spontaneously at high frequency by minor nucleotide changes in coat protein gene, and confirmed the previous results at the RNA level that MS2 and GA were related although the closeness between them seems somewhat remoter than that of groups III and IV (18, Inokuchi et al, unpublished data for the nucleotide sequence of group IV phage SP).