Nuclear Fusion in the Malpighian Tubes of a Blood-sucking Hemipteran

Abstract

When fifth instar nymphae or adults of the reduviid, Panstrongylus megistus, are subjected to a 4.5-month starvation period, nuclear fusion occurs in some of the epithelial cells of their Malpighian tubes. The affected nuclei had previously attained their maximal ploidy degrees by endomitosis. Nuclear fusion was demonstrated visually or with cytophotometric and karyometric procedures. Fusing nuclei pertaining to 64 C, 128 C, and 256 C Feulgen-DNA classes were found in the starved specimens, whereas unfusing nuclei pertaining to 32 C and 64 C classes were detected in normal controls and fasted insects. The doublings on nuclear areas in the fusing nuclei generally agree with those on Feulgen-DNA data. Exceptions showing nuclear sizes exceeding those expected from Feulgen-DNA contents are maybe concerned with an increase in nuclear hydrating levels and/or inclusion of cytoplasmic matter in the nuclei during their fusion.