To transfer only part of genome, X-ray irradiated suspension cell protoplasts of N. langsdorffii were fused with suspension cell protoplasts of N. glauca by polyethylene glycol. Somatic hybrid calli were selected by the growth in the hormone-free medium. Some of somatic hybrid calli from fusion with irradiated protoplasts indicated the loss of small subunit polypeptide of fraction 1 protein which was coded by N. langsdorffii nuclear DNA. Cytological analysis provided an information on significant decrease of chromosomes in somatic hybrid calli from fusion with irradiated protoplasts, compared with the somatic hybrid calli from fusion with non-irradiated protoplasts. In addition, isozyme analysis revealed that somatic hybrid calli from fusion with irradiated protoplasts lost particular bands of N. langsdorffli. These results demonstrate the tranfer of only part of genome from N, langsdorffii to N, glauca by fusion with X-ray irradiated protoplasts.
Gibberellin (GA) relationships in an induced dwarf mutant of barley, brachytic (gene symbol br2) were investigated. The dwarf mutant was suggested to have genetic blockade at the site of conversion from a "pool GA" (presumably GA19) to an "active GA" (presumably GA3) in the pathway of GA biosynthesis. An application of (2-chloroethyl) trimethylammonium chloride (CCC), an inhibitor of GA biosynthesis, to the corresponding normal form (cv. Svanhals) reduced the growth and that of GA3 to the dwarf mutant restored the reduced growth. In all possible hybrid combinations, among 3 dwarf genes, uz, br and br2, all F1 hybrids showed tall normal plant height, thus the site of genetic blockade, if any, may be different one another within these 3 dwarf genes.
Eleven desynaptic mutants of Oryza sativa L. were cytogenetically investigated. Mutants were induced by the treatment of fertilized egg cells with N-methyl-N-nitrosourea. Normal chromosome pairing occurred at pachytene in all mutants. Various numbers of univalents appeared at diakinesis and metaphase I in the mutants. The reduction of the mean chiasma frequency per bivalent as well as per cell were recognized in all mutants. The lower the mean chiasma frequency, the lower the mean bivalent frequency. The results of gene analyses indicate that each of the desynaptic mutants is governed by a single recessive gene and that at least 10 loci are represented.
A new acetate-requiring mutant was isolated in Neurospora crassa and termed as ace-8. The ace-8 gene is located on the left arm of the linkage group VII near the centromere between thi-3 and qa-3 genes. The ace-8 mutant strain lacks the activity of pyruvate kinase (EC 184.108.40.206). Accumulation of glycolytic intermediates is consistent with the enzyme lesion. The mutant strain is extremely sensitive to glycolytic sugars, glucose and sucrose, but grows well on a medium containing gluconeogenic carbon sources, acetate, ethanol and alanine.
Drosophila melanogaster strains homozygous for X chromosomes sampled from natural populations responded to upward and downward selection for glucose-6-phosphate dehydrogenase activity. Second and third chromosomes sampled from the homozygous strains showing a high enzyme activity as a result of selection have no stimulative effect on the enzyme activity. Flies which were made homozygous for X, second and third chromosomes sampled from "high-activity" strains also responded to selection. Since the fourth chromosome constitutes only a minor fraction of D, melanogaster genome, these findings suggest the presence of an extrachromosomal modifier which is responsible for regulation of the enzyme activity. Implication of these findings in adaptive evolution is discussed.
Mitochondrial DNA was isolated from rice with normal (fertile) and male sterile cytoplasms were analyzed by electrophoresis, the patterns were readily distinguishable between the two cytoplasmic types. It was found that mitochondria from male sterile cytoplasm contain DNA species of sizes 1.5 kilobase pairs (kb) and 1.2kb, in addition to the DNA of relatively much higher molecular weight. In contrast mitochondria from normal cytoplasm contained only one of these DNA species, that of higher molecular weight.
The chromosomes of the Japanese weevil, Catapionus gracilicornis Roelofs have been investigated in Aomori Prefecture. Both hexaploid (6x=63) and decaploid (10x=100) parthenogenetic races were found in Temma. The species is now known to have six parthenogenetic races, 2x, 3x, 4x, 5x, 6x, and 10x, as well as a diploid bisexual race. It was shown that pentaploid forms arose from hexaploid forms as I stated in 1980.
The chromosomes of the weevil, Blosyrus japonicus Sharp, have been investigated in Hokkaido. A triploid parthenogenetic race (3x=33) was found in Ishiyama-rikkyo, Sapporo. The species is now known to have four parthenogenetic races, 3x, 4x, 5x, 6x, as well as a diploid bisexual race. All these races have been found in Japan. This represents the highest number of different polyploid races observed in any parthenogenetic weevil.
Several seemingly unrelated phenomena-sterility, chromosome breakage, mutability, male recombination, and distorted segregation ratios-have been discovered independently by several investigators. They all have three striking properties: (1) The effects are confined to cells in the germ line; (2) they appear in hybrids between two strains, arbitrarily designated M and P; and (3) reciprocal matings differ, the effects appearing only when M females are mated to P males. The suggestion that these have a common etiology was first made by Kidwell, Kidwell, and Sved (1977), who also suggested that the syndrome be named "hybrid dysgenesis". This is now known to be caused by a transposable element, the P factor. The first suggestion that such an element is involved was made by Green (1977).<br> I will discuss especially the research of my colleagues, William Engels, Christine Preston, and Michael Simmons, but I will mention work done by many others. The very rapid progress in understanding the P factor has been made possible by the friendly cooperation and exchange of materials among several laboratories. This report is necessarily abbreviated. For those who would like to know more there is a recent review (Engels 1983), which contains much additional information and many references.