No abstract

Type conversions among the three types, P, Q and M, of the P-M hybrid dysgenesis in Drosophila melanogaster were examined. Among 54 isofemale lines established from two natural populations , about 30% of the lines have shown type conversions during laboratory culture for two years. These were M-~Q, Q-~M, P-~Q and P-+M in order of frequency. In hybrid lines (HMP) started from M x P crosses, flies receiving a P type chromosome rapidly changed their cytotype away from the M toward the P or the Q type . However, in flies consisted of only M strain-derived chromosomes, cytotype conversions were comparatively slow. Similarly, P factor activities of hybrid lines increased with generation number in flies having a P type chromosome in the genome but not in flies without it. M strain-derived chromosomes were isolated to make the HMP[e] series after several generations of exposure to the P type chromosome. In these series, P type lines appeared when the P type chromosome was removed in early generations of the HMP lines. P factors did not increase, however, with the same procedures in the later generations of the HMP lines. Circumstances related to type conversions in the P-M system were discussed: (1) P and Q factors and the M states must coexist in a genome and even in one chromosome. (2) P and Q factors or cytotype determinants transpose on a certain cytotype background.(3) How do the interactions between P or Q factors and cytotypes lead to expression of dysgenic traits?

The reconfiguration technique for a processor network is among the fault-toleraut techniques in monolithic realization of a multiprocessor network. The problem is composed of the mapping of logical processor element (PE) to physical PE and the physical realization of the logical connections. This paper considers twodimensional mesh array architecture and discusses the roiiting mechanism (required number of tracks) to support the processor mapping b a d on the compensation path. The eight adjacent neighbor is considered in the processor substitution in composing the path. It is shown that four tracks for each channel between PE are sufficient under the condition of no portexchange and no crossover. It is also shown that, when a compensation path exists under the four adjacent neighbor substitution condition, there exists a routing mapping using at most three tracks per channel. As to the evaluation of the number of tracks, the channei-cut in the dual relation to the routing path is introduced; this aids in both evaluation and proof.