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At least 631 records · Page 35Linked to original sources
PubMed1999

Construction of cellulase hyperproducing strains derived from polyploids of Trichoderma reesei.

The mycelial mat of Trichoderma reesei strain QM 6a was treated with 0.1% (w/v) colchicine solution for 14 days and designated M14. The cellulase productivity of strain M14 was not much higher than that of the original strain. When conidia of M14 were treated with ethylmethane sulphonate (EMS) solution, the cellulase hyperproducers, M14-1 and M14-2, were isolated using a selection medium containing Avicel. The DNA content of M14-1 and M14-2 was higher than that of the original strain. Cellulase productivity per mycelium of these strains increased and was higher than that of the original strain. The cellulase productivity did not change through ten generations when these strains were cultivated successively on a medium containing Avicel. It was concluded that cellulase hyperproducers, whose cellulase productivity per mycelium increased, could be obtained when the conidia of strain M14 were treated with EMS.

Cellulase↗
PubMed2000

Cellulase hyperproducers constructed from polyploids of Lentinus edodes.

A mycelial mat of Lentinus edodes was treated with 0.01% (w/v) colchicine solution for 240 h at 26 degrees C and autopolyploidization occurred. The mycelia were treated subsequently with the haploidizing reagent, benomyl, and fanshaped sectors were produced from colonies. Among such sectors, cellulase hyperproducers could be selected. The cellulase productivity of the hyperproducer, L1, did not decrease through five generations.

Benomyl↗
PubMed1975

[Basic factors in the cerebellar Purkinje cell polyploidization in chicken embyogeny. II. The changes in the content and concentration of proteins, protein SH-groups and RNA in the cytoplasm of Purkinje cells in the process of their differentiation and specialization].

Cytophotometric study of the cerebellum Purkinje cells in the chick embryos(10th-21st day) showed that the total amount of protein increased at this period proportionately to the growth of cells, its concentration remaining relatively constant. Thebasic and acid proteins ratio changed, the acid proteins increasing. Content of the protein SH-group increases considerably during the tigroid and eneurofibrillas formation, - simultaneously with the conent of RNA. The periods of intensification of the protein synthesis coincide with the morpho-functional maturation of neurons and formation of signs characterizing the maturity of the embryo as a whole. Supposedly the changesin the activity of nuclear apparatus of the cells, manifested in the increase of nuclear size and the number and size of nucleoli, underlie this process.

Animals↗
PubMedDate not supplied

[Polyploid hybrids of industrial yeast races and the prospects for using them in production].

The ploidity of the parent forms, hybrids, and two industrial yeast races was studied by determining the content of DNA per cell, the ratios during allel splitting, the dimensions and volumes of the cells. The triploid nature of the baker's race 14--2 and some hybrids was found (for example, the productive hybrid 112 obtained by crossing the distillery and baker's races). The results obtained suggest the possibility to apply the techniques of hybridization and polyploidy for selecting productive yeast strains.

Alleles↗
PubMed2000

Ubiquity of the St chloroplast genome in St-containing Triticeae polyploids.

Interspecific hybridization occurs between Tritceae species in the grass family (Poaceae) giving rise to allopolyploid species. To examine bias in cytoplasmic DNA inheritance in these hybridizations, the sequence of the 3' end of the chloroplast ndhF gene was compared among 29 allopolyploid Triticeae species containing the St nuclear genome in combination with the H, I, Ns, P, W, Y, and Xm nuclear genomes. These ndhF sequences were also compared with those from diploid or allotetraploid Triticeae species having the H, I, Ns, P, W, St, and Xm genomes. The cpDNA sequences were highly similar among diploid, allotetraploid, allohexaploid, and allooctoploid Triticeae accessions containing the St nuclear genome, with 0-6-nucleotide (nt) substitutions (0-0.8%) occurring between pairs of species. Neighbor-joining analysis of the sequences showed that the ndhF DNA sequences from species containing the St nuclear genome formed a strongly supported clade. The data indicated a strong preference for cpDNA inheritance from the St nuclear genome-containing parent in hybridizations between Triticeae species. This preference was independent of the presence of the H, I, Ns, P, W, and Xm nuclear genomes, the geographic distribution of the species, and the mode of reproduction. The data suggests that hybridizations having the St-containing parent as the female may be more successful.

Chloroplasts↗
PubMed1975

[Chief factors in the polyploidization of cerebellar Purkinje cells during chicken embryogenesis. I. Characteristics of the morphologic differentiation and growth of Purkinje cells].

The Purkinje cells of the cerebellum of chick embryos differentiating from the neuroblasts of the ventricular epithelium by the 10th day of development continue the process of morpho-functional specialization, which is characterized by formation of tigroid and neurofibrilles, by intensive growth of cells, decrease of nuclear-plasmatic and increase of nucleolar-nuclear relations. At the period of hatching the specialization of the Purkinje cells comes to an end.

Animals↗
PubMed2002

[Evaluation of phylogenetic relationships between five polyploid Aegilops L. species of the U-genome cluster by means of chromosomal analysis].

Four tetraploid (Aegilops ovata, Ae. biuncialis, Ae. columnaris, and Ae. triaristata) and one hexaploid (Ae. recta) species of the U-genome cluster were studied using C-banding technique. All species displayed broad C-banding polymorphism and high frequency of chromosomal rearrangements. Chromosomal rearrangements were represented by paracentric inversions and intragenomic and intergenomic translocations. We found that the processes of intraspecific divergence of Ae. ovata, Ae. biuncialis, and Ae. columnaris were probably associated with introgression of genetic material from other species. The results obtained confirmed that tetraploid species Ae. ovata and Ae. biuncialis occurred as a result of hybridization of a diploid Ae. umbellulata with Ae. comosa and Ae. heldreichii, respectively. The dissimilarity of the C-banding patterns of several chromosomes of these tetraploid species and their ancestral diploid forms indicated that chromosomal aberrations might have taken place during their speciation. Significant differences of karyotype structure, total amount and distribution of C-heterochromatin found between Ae. columnaris and Ae. triaristata, on the one hand, and Ae. ovata and Ae. biuncialis, on the other, evidenced in favor of different origin of these groups of species. In turn, similarity of the C-banding patterns of Ae. columnaris and Ae. triaristata chromosomes suggested that they were derived from a common ancestor. A diploid species Ae. umbellulata was the U-genome donor of Ae. columnaris and Ae. triaristata; however, the donor of the second genome of these species was not determined. We assumed that these tetraploid species occurred as a result of introgressive hybridization. Similarity of the C-banding patterns of chromosomes of Ae. recta and its parental species Ae. triaristata and Ae. uniaristata indicated that the formation of the hexaploid form was not associated with large modifications of the parental genomes.

Chromosome Aberrations↗
PubMed2003

Are all fishes ancient polyploids?

Euteleost fishes seem to have more copies of many genes than their tetrapod relatives. Three different mechanisms could explain the origin of these 'extra' fish genes. The duplicates may have been produced during a fish-specific genome duplication event. A second explanation is an increased rate of independent gene duplications in fish. A third possibility is that after gene or genome duplication events in the common ancestor of fish and tetrapods, the latter lost more genes. These three hypotheses have been tested by phylogenetic tree reconstruction. Phylogenetic analyses of sequences from human, mouse, chicken, frog (Xenopus laevis), zebrafish (Danio rerio) and pufferfish (Takifugu rubripes) suggest that ray-finned fishes are likely to have undergone a whole genome duplication event between 200 and 450 million years ago. We also comment here on the evolutionary consequences of this ancient genome duplication.

Animals↗