The structural locus for a-amylase (AMY) in Drosophila melanogaster is duplicated and divergently transcribed. These two genes are designated as Amy-p and Amy-d, respectively. We searched for the cis-acting regulatory elements for full expression of the duplicated Amy-p and Amy-d loci, by injecting plasmid constructs containing sequences from the Amy locus into preblastoderm embryos of an AMY-null strain and measuring exogenous AMY activity produced in transformed host larvae (i.e., the transient expression assay). Relative activities of endogenous amylase isozymes, AMY-1 and AMY-3, in extracts of AMY1,3 larvae of a Canton-S are almost the same. However, three independently isolated Amy-p1 constructs with only the 5' upstream regions of Amy-p1 expressed a very low AMY-1 activity. Two other Amy-p1 constructs with the 5' upstream region of Amy-d3 in addition to that of Amy-p1 produced a high activity. Thus, the 5' upstream region of Amy-d3 is necessary for full expression of Amy-p1. In order to locate cis-regulatory elements within the 5' region of Amy-d3, a series of hybrid constructs including this region were tested to locate them. Our results clearly show that the cis-acting regulatory sequences required for full expression of Amy-p1 are located between the base pairs at -304 and -372 upstream of Amy-d3 gene. In other words, only a short region located upstream of Amy-d3 was found to be necessary and sufficient for the full expression of Amy-p1 in addition to its promoter. This region seems also necessary for the expression of Amy-d3.
Meiotic configuration at microsporogenesis was examined in several wild tetraploid and hexaploid taxa of tuber-bearing Solanum. A high frequency of bivalents was observed in all of the species studied: four tetraploid and one hexaploid taxa in Series Conicibaccata, one tetraploid taxon in Series Piurana, a Mexican tetraploid species in Series Longipedicellata, and three hexaploid taxa in Series Demissa. An outlook on evolutionary significance of the cytologically disomic behavior in the polyploid taxa of the tuber-bearing Solanum was presented. Further, a genetic efficiency in introgression was discussed for an efficient genetic manipulation with these valuable, but under-utilized polyploid genetic resources.
Chloroplast DNAs (cpDNAs) of Agropyron glaucum, Ag. trichophorum and Haynaldia villosa were studied using alloplasmic hybrids of common wheat (Triticum aestivum; nuclear donor) with cytoplasms of the respective species. Chloroplast genome sizes of the two Agropyron species and Hy. villosa were very close to 135 kb of common wheat. Restriction maps were constructed using seven restriction enzymes. Eight fragment length mutations (deletions/insertions) and five recognition site mutations were detected among 167 sites studied. CpDNAs of Agropyron, Hy. villosa and common wheat were very closely related: Base substitution rate per 100 base pairs (d) was 0.10 between Hy. villosa and common wheat, 0.19 between common wheat and Agropyron, and 0.29 between Agropyron and Hy. villosa. There was only one site difference (Hindlll site) between the two Agropyron species (d=0.05).
The genetic polymorphism of placental glucose dehydrogenase (GDH) was investigated in 300 Korean placentae using horizontal starch gel electrophoresis. The allele frequencies for GDH1, GDH2 and GDH3 were 0.537, 0.440 and 0.005, respectively, which were similar to those in Japanese. We also observed an anodal allele which was similar to the GDH4 originally reported in Chinese populations at a low frequency of 0.015. An additional new cathodal allele (named GDH6) was observed in the present study with a very low frequency of 0.003.
We have isolated a cDNA homologous to the yeast DMC1 and RAD51 genes from Drosophila melanogaster. The DMC1 and RAD51 genes of Saccharomyces cerevisiae are known to play crucial roles during meiosis and during both meiosis and mitosis, respectively, and their gene products are homologous to each other and to the RecA protein of Escherichia coli. The cDNA cloned here contains an open reading frame that encodes 336 amino acids. Sequence analysis of the corresponding genomic DNA fragment showed one short intron existing in the coding region as in the DMC1 gene, but not in the RAD51 gene. By in situ hybridization to the salivary gland chromosomes, the recA-like gene was cytologically mapped to 99D of the third chromosome.
The cps3 gene of the fission yeast, Schizosaccharomyces pombe, was previously identified as a mutation conferring supersensitivity to the spindle poison, isopropyl N-3-chlorophenyl carbamate (CIPC). A 3.2 kb DNA fragment that complements the mutant phenotype was cloned from a S. pombe genomic library. The base sequence analysis showed that the fragment contains a maximum 1086 nucleotide open reading frame and that the putative product consists of 362 amino acids, having a molecular weight of 39.3 KDa. No significant homology of the potential product with known proteins could be found by database searches. A disruptant of the gene, produced by insertion of a ura4+ fragment was able to germinate, but not to undergo cell division, suggesting that the gene to be essential for the cell cycle progression. The disruption experiment suggests that the gene is an extragenic suppressor of cps3 mutation.
Malate dehydrogenase (MDH) activity in freshwater shrimps, Paratya compressa, Caridina leucosticta and Neocaridina denticulata (Decapoda: Atyidae), was examined by starch gel electrophoresis. In accordance with the previous results, most populations of P. compressa had only one activity zone (MDH-1). The Biwa Lake population, however, was found to have two activity zones (MDH-1 and MDH-2). Since both had a triple-banded phenotype and since densitometric measurements showed the expected activity pattern (1:2:1), it is most likely that they are dimeric enzymes and are encoded by two independent loci (Mdh-1 and Mdh-2). C. leucosticta and N. denticulata examined had the two activity zones. But some individuals of both species showed a null phenotype in either of the two zones but not in both. Possibility that in most populations of P. compressa null allele at the Mdh-2 locus was fixed was discussed.
Plasmid-like DNAs were isolated from mitochondria in many stocks of Para- mecium caudatum. Fifty-two among 68 stocks examined contained unique double-stranded DNAs (designated type I) ranging from 6.0 to 6.8 kb in length, and 12 stocks contained a set of 4 kinds of DNAs (8.2, 4.1, 2.8 and 1.4 kb; type II). Five of the stocks containing the type-I DNA had an additional 8.9-kb DNA (type III). No plasmid-like DNAs were found in the remaining 4 stocks. All these DNAs are linear and closely associated with proteins which can be removed only after proteinase-K digestion, suggesting that they exist as unique DNA protein complexes in mitochondria. Restriction and Southern blot analyses revealed a large sequence divergence among both type-I and -II DNAs. Type-I DNAs were found in every lineages of mitochondrial genomic DNA (mtDNA) which were inferred from restriction analyses. Type-II DNAs were, in contrast, scattered throughout the evolutionary tree of the mtDNAs. No obvious relations were found between the distribution of the DNAs and that of syngens (mating-type groups). Type-I DNAs were also found in other species of Paramecium, P. jenningsi and P. multimicronucleatum, and type-II DNAs in P. polycaryum.
Using fluorescent in situ hybridization (FISH) method, gene encoding the catalytic subunit of protein phosphatase type 1β (PPP1CB) in human and its corresponding gene in rat (PP1δ) and mouse (dis2m2) were mapped to human 2p23, rat 6q21-q23, and mouse 12D, respectively. These results indicate that PPP1CB is a member of conserved syntenic group. It is shown that the genes encoding catalytic subunit of protein phosphatase type 1 family (PP1α, PP1β, and PP1γ in human and those corresponding genes in rat and mouse), in spite of their high identity, are located to different chromosomes in these three species.
Drosophila RBP-Jκ is a novel sequence-specific DNA binding protein encompassing the integrase motif which is highly conserved in various organisms. Its gene has been shown to be identical to Suppressor of Hairless which regulates adult peripheral nervous system (PNS) development. To elucidate the precise function of the RBP-Jκ protein in adult PNS development, we analyzed transgenic flies that misexpress the RBP-Jκ protein. Such studies have shown that RBP-Jκ regulates PNS cell fate in at least two steps: commitment to sensory mother cell by lateral inhibition and terminal differentiation into the socket and shaft cells. Taken together with analysis of phenotypes of Suppressor of Hairless mutants, RBP-Jκ shows the synergistic activity with neurogenic genes.
Three species of Shorea (S. leprosula, S. acuminata and S. cursitii) were collected from a natural forest reserve of Malaysia and analyzed for genetic variation using the technique of random amplification of polymorphic DNA (RAPD) by the polymerase chain reaction (PCR). The average number of nucleotide substitutions was estimated. The nucleotide diversities within species were very similar and larger than those found in Drosophila melanogaster. The nucleotide divergences between these species are about 1.5 times the nucleotide diversities within the species, indicating that these species diverged from a common ancestor relatively recently.
Partially sterile F1 barley plants were found when some Ethiopian varieties were crossed with Tayeh 1 (Chinese landrace), even though the parents were completely fertile. This hybrid sterility is shown to be controlled by two duplicate genes (sfg1 and sfg2). Because this gene interaction affects the female gamete only, the female gametes carrying the both sfg1 and sfg2 genes became sterile, the end result being that seed fertility of the F1 plants is decreased to around 75%. Seed fertility was not significantly influenced by cytoplasms and genetic backgrounds of the F1 plants, and years grown the F1 plants.