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The constant (C; ref.3) gene segment of the immunoglobulin kappa light chain and about 1 kb upstream as well as downstream of the segment have been sequenced. The sequences of the C gene segment itself and parts of the upstream region were determined both in liver and in myeloma T DNA clones derived from the same mouse inbred strain. The sequences were identical, i.e. no somatic mutations were detected. Two sites in the region not coding for protein are discussed as possible targets of aberrant variable (V) gene translocations. Doublet frequencies were calculated in the approx. 2500 bp of the C region sequence reported in this paper and in the approx. 3400 bp of two rearranged V

The nucleotide sequence of a cloned Muntjak satellite 1A repeat unit (Muntiacus muntjak vaginalis) was determined. The repeat is 807 base pairs (bp) long. By introducing minor deletions and insertions, the whole sequence of the satellite can be arranged in 27 subrepeats of 31 bp length. Although diverged relative to each other, all subrepeats show a homology of more than 53% with the common consensus sequence. In 29 out of the 31 bp the consensus sequence of the Muntjak satellite subrepeat is identical to the 31-bp subrepeat of the bovine satellite 1.715. This suggests that both satellites are derived from a common ancestral sequence. The results have interesting implications for the evolution of the two satellites.A significant amount of the eucaryotic genome is composed of highly repetitive DNA sequences which are arranged in tandem arrays over long stretches of DNA (satellite DNAs); (for reviews see [I, 21). A general feature of the satellite DNAs are minor sequence variations between different repeat units, which are often clustered in segments or domains (e.g. mouse satellite [3]). There is evidence that these clustered sequence variants might correspond to specific chromosomal locations (e.g. . To obtain more insight into the evolution of the satellite DNA and the significance of the chromosome-specific variants, it would be important to analyse satellite sequences of closely related species and to correlate their structure with the chromosomal evolution.We are addressing this question in our studies on the structure and chromosomal location of satellite DNAs in the Indian Muntjak, a species with a very low number of chromosomes (male: 277 = 7). We have recently isolated and partially characterized a satellite DNA from this species (satellite IA [7]). Homologous sequences are also present in the satellite DNAs of several related bovidae (J. B., H. Neitzel, U. Benedum and F. F., unpublished). Since the evolutionary steps for the reduction of the chromosomes have been studied in detail, these species are especially well suited to correlate the evolution of the satellites with the evolution of the chromosomes.The satellite IA sequences from the Indian Muntjak have turned out to be particulary interesting in context with the evolution of the Muntjak X chromosome. This chromosome is believed to have evolved from a centric fusion of an evolutionarily older X chromosome and an autosome (e. g. [8, 93). The location of the satellite IA on both sides of the X-chromosome centromere but not at the corresponding position of the chromosome Y1, the homologue of the long arm of the X chromosome, provided new information on the mechanism of the centric fusion [7].We have extended our investigation concerning the Muntjak satellite IA and determined the entire sequence of the repeat unit. Most significantly, the sequence was found to have an internal structure which shows high similarity to the bovine satellite 1.71 5. MATERIALS AND METHODS DNAs and bacterial strainsDNA from cultured cells of Muntiacus muntjak vaginalis (Ame...

2318 bp downstream of the CK (1) gene segment were sequenced in a clone (L1-D) derived from mouse liver DNA. The 966 bp at the 5' side of this stretch were found to be identical to a sequence which had been determined previously in a myeloma T derived clone, i.e. no somatic mutations had occurred in the transition from the germline to the rearranged configuration. The remaining 1352 bp had not been known and extend the sequenced part of the mouse JK-CK region to about 7.5 kb. Within the newly sequenced area three BspRI sites have been located which were used in chromatin studies (Weischet et al., accompanying publications). In L1-D sequences have been found which are possible targets of aberrant recombination events.