The distribution of the fertility restorer genes for Ogura cytoplasmic male sterility in Raphanus raphanistrum, Japanese wild radish, and cultivated radishes (R. sativus) was studied by observing the pollen fertility of the F₁'s from crosses with a male sterile strain having the Ogura cytoplasm. The restorer gene is widely distributed in the wild species and wild radishes irrespective of cytoplasm type. Among the cultivated radishes, the European and Chinese varieties had the restorer gene, while most of the Japanese cultivars did not.
The allelism of three restorer genes from R. raphanistrum, Japanese wild radish, and the European cultivar was estimated by the segregation of the fertility in the progenies produced by crosses between strains with different restorer genes. The results suggested that the restorer genes from these three sources were allelic.

View full abstract

Nine Fagopyrum accessions which are suspected to be new species were examined for morphology and crossability with their closely related species. Three accessions similar to F. leptopodum are considered to be members of F. leptopodum because of no difference in 14 qualitative characters examined and fertility of hybrids between them. One accession similar to F. gracilipes is included in F. gracilipes by the same reason. Two other F. gracilipes-like accessions are considered to be a new species based on morphological differences and sterility of hybrids. Three accessions related to F. pleioramosum and F. callianthum had characters different from both species and could not be included into either species. Phylogenetic relationships among the suspected accessions and related species were examined based on isozyme variability and nucleotide sequences of the internal transcribed spacer (ITS) region of nuclear ribosomal DNA (nrDNA). The accessions considered to be new species were distantly related to the group of their related species in the molecular phylogenetic trees. In contrast, those accessions considered to be F. leptopodum and the accession considered to be F. gracilipes based on morphological characters and crossability were included in the respective group of their related species. Thus these molecular phylogenetic trees support the classification based on morphology and crossability.

View full abstract

In the chromosome region 89A of Drosophila melanogaster, a few meiotic genes have been suggested to exist besides c3G and rec. We carried out local mutagenesis using a strain carrying a P element-insertion (plwB) at 89A, and obtained new genetic variants. Two are female sterile mutations, an allele of the homeless locus (hls¹⁶⁷) and a new mutation tibi (tbi), and three are lethal mutations at the serpent locus. The tbi mutation is a paternally-rescuable maternal-effect-lethal. Destabilization of the P elements revealed that these mutations were caused by P element-insertions, and produced 12 deletion lines. These lines were then used for systematic complementation tests. The results showed that: (1) hls, tbi and at least three lethal genes in addition to c3G, rec and l(3)89Aa are located within the deletion of Df(3R)c3G2 (89A2-3; 89A4-5); (2) the gene order is rec, tbi, hls (from centromere to telomere), and both c3G and l(3)89Aa are possibly located proximally. We cloned 117 kb of DNA from this region by plasmid rescue and chromosome walking, and mapped several of the breakpoints of the deletions. These analyses delimited the rec gene to within 21 kb of the cloned DNA, although the c3G gene could not be located on the molecular map.

View full abstract

Two loci producing white flowers have been identified in the common morning glory, Ipomoea purpurea. At the W locus, ww individuals produce flowers with white corollas and pigmented rays, while at the A locus, aa individuals produce flowers with white corollas, and a*a* individuals produce variegated corollas. To determine whether these two loci correspond to regulatory or structural genes, six structural genes required for anthocyanin synthesis were cloned and their expression pattern was examined in genotypes with white and pigmented flowers. In ww flower buds, expression of all six structural genes was greatly reduced or eliminated, indicating that the W locus encodes a regulatory gene. By contrast, genotype at the A locus did not affect expression of any of the structural genes, suggesting that the A locus may encode one of those structural genes. An evolutionary comparison of structural gene regulation in maize, snapdragons, petunias, and morning glories suggests that regulatory control of the anthocyanin pathway is evolutionarily labile.

View full abstract

Restriction fragment length polymorphisms (RFLPs) of EcoRI- and ClaI-digested chloroplast DNA (cpDNA) within the genus Glycine subgenus Soja were characterized. Two mutations were found to be responsible for the EcoRI and ClaI restriction site polymorphisms, and both were located in a region in which many ribosomal protein genes are clustered. This region is within the large single copy region of cpDNA and is located close to an inverted repeat. The locations of restriction sites of EcoRI and ClaI in the cpDNA region were analyzed by DNA gel-blot analyses and PCR amplification, which were followed by sequencing analyses. The EcoRI site polymorphism was found to have occurred in the intergenic spacer between rps11 and rpl36, while the ClaI site polymorphism was located within the 3' part of the coding region of rps3. The mutations that cause EcoRI and ClaI polymorphisms were both found to be single base substitutions. In addition to these polymorphisms, novel sequence variations in soybean cpDNA were detected near the sites of these mutations. Previously, it was shown that cultivated soybeans could be classified into three groups (I, II, and III) based on their cpDNA RFLPs. A comparison of the cpDNA sequences of soybeans in the present study was consistent with the notion that the cpDNA of group II soybeans is an intermediate between the cpDNAs of groups I and III.

View full abstract

The evolutionary relationships among Japanese pond frogs (Rana nigromaculata, R. porosa porosa, and R. p. brevipoda) were investigated by analyzing nucleotide sequences of mitochondrial cytochrome b (cyt b) and 12S rRNA genes. The nucleotide sequences of 444-bp segment of the cyt b gene and 410-bp segment of 12S rRNA gene were determined by the PCR-direct sequencing method using 18 frogs from 13 populations of Japanese pond frogs, and phylogenetic trees were constructed by the neighbor-joining and maximum likelihood methods using R. catesbeiana as an outgroup. The sequenced 444-bp segment of cyt b gene provided 69 variable sites, and the sequenced 410-bp segment of 12S rRNA gene provided 21 variable sites. The numbers of nucleotide substitutions per site of the cyt b gene within ingroup were 0.0022~0.0205 at the populational level, 0.0368~0.0462 at the racial or subspecific level, and 0.1038~0.1244 at the specific level, whereas those of the 12S rRNA gene were 0~0.0074 at the populational or subspecific level, and 0.0378~0.0456 at the specific level. Most nucleotide substitutions within ingroup occurred at the third codon position of the cyt b gene and were silent mutations. High frequencies of transitions relative to transversions were shown at cyt b and 12S rRNA genes within ingroup. The phylogenetic trees constructed from the nucleotide sequences of the cyt b gene showed that after outgroup R. catesbeiana separated from ingroup frogs, ingroup Japanese pond frogs diverged into R. nigromaculata and R. porosa, then the latter diverged into R. p. porosa, R. p. brevipoda (the typical Okayama race), and the Nagoya race of R. p. porosa. The phylogenetic trees constructed from the nucleotide sequences of the 12S rRNA gene also showed distinct divergence between two species, but not any divergence within species.

View full abstract

Structural variations between great ape and human chromosomes due to pericentric inversions and translocations have created at apparent controversy during the reconstruction of hominoid phylogeny. One such variation involves human chromosome 5, which is equivalent to chromosome 4 in chimpanzee and orangutan but equivalent to segments of chromosomes 4 and 19 in gorilla. Obviously, neither banding patterns nor centromeric indecies in these chromosomes match. The pathological condition of cri du chat syndrome is due to the cytogenetic deletion of band p15. 2 of chromosome 5. Is this region involved during pericentric inversion of apes chromsome 4? We used a human cosmid probe for cri du chat syndrome as a phylogenetic marker in search of the aforementioned question. The genomic sequences for cri du chat syndrome region were conserved in chimpanzee (PTR4) and orangutan (PPY4) but displayed a positional divergence in gorilla on chromosome 19(GGO19). In addition, we used a human cosmid DNA probe for DiGeorge syndrome which is located on chromosome 22 band q11.2 and was conserved within band 23q11.2 in apes. The loci specific human genomic probes may help to describe the inversions and translocations for other chromsomes.

View full abstract