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PubMed2003

Reproductive capacities in the polyploid males of spined loaches from the unisexual-bisexual complex, occurred in the Moscow River.

The unisexusal-bisexual complex of spined loaches from genus Cobitis, occurred in the Moscow River, includes two tetraploid forms. One of them consists of males and females. The studies of spermatogenesis as well as spermatozoa mobility and ultrastructure, of these males were performed simultaneously with experimental crosses to define their reproductive capacities. The testis visually looked undeveloped in the most of cases. The study of spermatogenesis revealed that they reached the stage of starting spermatogenesis wave. The most cells were spermatocytes I or II. In some males, several seminal tubules were filled with connective tissue, displaced germ cells. Spermatozoa of tetraploid males looked unmoved under the light microscopy. The study of male gonads by electron microscopy revealed that the most of germ cells were destroyed. Normal spermatozoa were absent. Experimental crosses between gynogenetic triploid females and tetraploid males revealed that these males were capable to stimulate gynogenetic development, but not effective: only 4.7 % oftriploid eggs inseminated with sperm from tetraploid males survived up to hatching. But 56.6 % of obtained hatchlings normally developed and survived up to 58-days age.

Animals↗
PubMed2004

[Chromosome maps of trilliaceae: II. A study of the genome composition in polyploid species of the genus Trillium by fluorescence nucleotide base-specific staining of heterochromatic chromosome regions].

Chromosome banding with nucleotide base-specific fluorochromes chromomycin A3 (CMA) and Hoechst 33258 (H33258) was used to study the karyotypes and to construct cytological maps for diploid Trillium camschatcense (2n = 10), tetraploid T. tschonoskii (2n = 20), hexaploid T. rhombifolium (2n = 30), and a triploid T. camschatcense x T. tschonoskii hybrid (T. x hagae, 2n = 15). With H33258, species- and genome-specific patterns with numerous AT-rich heterochromatin bands were obtained for each of the four forms; CMA revealed a few small, mostly telomeric GC-rich bands. In T. tschonoskii, the two subgenomes were similar to each other and differed from the T. camschatcense genome; on this evidence, the species was considered to be a segmental allotetraploid. In T. x hagae, one T. camschatcense and both T. tschonoskii subgenomes were identified. The subgenomes of T. rhombifolium only partly corresponded to the T. camschatcense and T. tschonoskii genomes, in contrast to the morphologically identical Japanese species T. hagae. This was assumed to indicate that allohexaploids T. rhombifolium and T. hagae originated independently at different times; i.e., their origin is polyphyletic. Based on the chromosome maps, a new nomenclature was proposed for the Trillium genomes examined: K1K1 for T. camschatcense, T1T1T2T2 for T. tschonoskii, T1T1T2T2 for T. x hagae, and K1RK1RT1RT1RT2RT2R for T. rhombifolium.

Chromosome Mapping↗
PubMed2004

Agrobacterium-mediated transformation of polyploid cereals. The efficiency of selection and transgene expression in wheat.

Three combinations of Agrobacterium tumefaciens strains and vectors were used in the transformation of selected Polish wheat cultivars. The combinations were: two hypervirulent strains, AGL1, containing the pDM805 binary plasmid, and EHA101, containing pGAH; and the common Agro strain LBA4404, harboring the super-binary pTOK233 vector. pDM805 contained bar under the control of Ubi1 promoter, pGAH had nptII under nos, and pTOK233 had hpt under 35S. Additionally, pDM805 and pTOK233 carried the gus reporter gene under the Act1 promoter or 35S promoter, respectively. The highest selection rate was 12.6% and was obtained with EHA101(pGAH) on a kanamycin-containing medium. Sixty-five of the plants grown on that medium were PCR positive. The second best combination was LBA4404(pTOK233) and kanamycin selection, which gave an average transformation rate of 2.3%. Phosphinothricin selection gave 1.0% transformation efficiency, while hygromycin, depending on the strain/vector used, gave from 0.2 to 0.4%. PCR tests in T1 revealed that 67% of the lines showed a 3:1 segregation ratio, and 11% a 15:1 ratio, while in 22%, segregation was non-Mendelian. The high number of T0 transgenic plants containing one copy of the transgene was confirmed via Southern blot analysis. Kanamycin resistance in the T1 generation was very low; in some lines, all the progeny were kanamycin sensitive. GUS expression, only tested in young T1 plants, was in agreement with Mendelian segregation in three out of the twelve tested. The factors influencing the efficiency of selection and transgene expression are discussed in this paper.

Agrobacterium tumefaciens↗
PubMed2006

On the abundance of polyploids in flowering plants.

The wide distribution of polyploidy among plants has led to a variety of theories for the evolutionary advantages of polyploidy. Here we claim that the abundance of polyploidy may be the result of a simple ratcheting process that does not require evolutionary advantages due to the biological properties of organisms. The evolution of polyploidy is a one-way process in which chromosome number can increase but not decrease. Using a simple mathematical model, we show that average ploidal level within a plant lineage can continually increase to the levels observed today, even if there are ecological or physiological disadvantages to higher ploidy. The model allowed us to estimate the average net speciation and polyploidy rates for ten angiosperm genera. Based on these estimates, the model predicts distributions of ploidal levels statistically similar to those observed in nine of the 10 genera.

Biological Evolution↗
PubMedDate not supplied

[Effect of treatment with p-fluorophenylalanine on the mating capacity of industrial polyploid yeasts].

Brewing yeast strains of the genus Saccharomyces uvarum (carlsbergensis) were grown on media containing p-fluorophenylalanine (p-FPA). After the treatment, non-sporulation colonies were selected, and these were mated with haploid strains of flocculent and amylolytic yeasts of the genus Saccharomyces. The selected hybrids, which carried the greater part of the parental genetic markers and produced asci containing 2,3 and 4 spores per ascus, were placed on sporulation medium. Some aspects of the probable action of p-FPA are discussed.

Industrial Microbiology↗
PubMedDate not supplied

[Nucleotide sequences of 5S rRNA genes of polyploid species of wheat and Aegilops species].

Primary structures of 5S rRNA genes and of non-transcribed spacers between them were determined in families of 5S DNA repeats 420 and 500 b.p. long in 8 wheat and Aegilops species. The high conservatism of sequences coding for 5S rRNA, 3'- and 5'-ends of non-transcribed spacers was shown not to depend on the evolutional position, ploidy level and genomic composition of species. The activity of transcription of 5S rRNA cloned genes was determined in vitro. The functional heterogeneity was revealed in each family of repeats due to the existence of exchanges of separate nucleotides within the internal transcription control region. A greater deficiency of CpG dinucleotide was revealed in 5S rRNA genes than in non-transcribed spacers.

Base Sequence↗