Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 12

Liczba wyników na stronie
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników

Wyniki wyszukiwania

help Sortuj według:

help Ogranicz wyniki do:
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
Wild pear (Pyrus pyraster, syn. P. communis var. pyraster) is thought to be one of the species that gave rise to all other members of the genus Pyrus, although intraspecific hybridizations with cultivated varieties could cause the disappearance of original species characteristics. S-RNase alleles from 7 different wild pear individuals, collected from various regions of Poland, were cloned on the basis of the PCR method and nucleotide sequence analyses. The hypervariable (HV) region is responsible for allele-specific S-RNase activity in the self-incompatibility mechanism. The high level of polymorphism of its sequences may constitute a source of valuable phylogenetic information. From all individuals, 14 sequences were obtained successfully, and 9 of them were novel alleles. Phylogenetic analysis of these alleles was based on the amino acid sequence interpretation of coding regions and intron nucleotide sequences. The research conducted on a limited pool of available P. pyraster alleles gives only an initial insight into possible S-RNase allele polymorphisms in wild populations. At this stage, the results do not confirm a strong influence of cultivated pear species on the wild pear.
The research was aimed to elaborate a method for selection of male plants (XY, YY) and female ones (XX) as well as for identification of supermale genotypes (YY) among male phenotypes. The population obtained by self-pollination of andromonoecious plants was analysed. In order to identify the bands differentiating the male from the female genotypes, Bulk Segregant Analysis (BSA) was carried out. Primers identified by BSA analysis were used for RAPD amplification on the template of the male and female individuals. Among the products obtained by the use of primer OPB-20, some bands were linked with sex. A band of about 700 bp was found in all female plants, and in 4 phenotypically male specimens. In the male plants, the band showed a much lower intensity, compared with the female specimens. It seems that this fragment can be linked to the X chromosome in the investigated specimens. In the female specimens with XX karyotype, template duplication occurs and hence the band intensity is twice as high as in the XY karyotype. Three male plants did not include the OPB-20-700 fragment so they could potentially have the supermale (YY) karyotype. If the obtained marker proved its usefulness for identification of supermale plants, it could become a valuable tool facilitating breeding work.
Diallel crosses of P. communis cultivars: ‘Amfora’, ‘Radana’, ‘Red Williams’, ‘Carola’, ‘Conference’, and ‘Dicolor’, were conducted under orchard and laboratory conditions at temperatures of 20oC and 28oC . Based on pollen tube observations and after the determination of the S genotypes, the usefulness of these pear cultivars as cross pollinators was evaluated as good and very good.
A local population of Pyrus pyraster was studied in dry and warm habitats: xerothermic grasslands Potentillo-Stipetum capillatae and Adonido-Brachypodietum, as well as thermophilous oak forest Quercetum pubescentipetraeae in the forest-steppe Bielinek Reserve (NW Poland). Our aims were to assess: (1) the ability of this species to adapt to extremely dry sites, as a pioneer woody plant; (2) its phytosociological position; and (3) morphological variation and genetic diversity of the local population. The pear trees in Bielinek Reserve seem to reach an optimum in shrub communities of the class Rhamno-Prunetea, but tree age clearly indicates that the grasslands were colonized by wild pear trees already before the shrub communities developed. This indicates that P. pyraster can colonize very dry, eroded sites, such as steep sunny slopes covered by xerothermic grasslands. Wild pear trees form plant communities that are a seral stage followed by forest-shrub communities or thermophilous forests. The species in xerothermic shrub communities of the reserve shows a high constancy. It is also very resistant to extreme temperatures, insolation, drought, and erosion. Its tree-ring width (on average 1.1 mm per year) was strongly related to precipitation and temperature in spring and summer. High precipitation resulted in wider tree rings, while dry years (associated with high air temperature) caused a decrease in tree-ring width. Another significant factor is precipitation in winter, which had a positive influence on tree-ring width. Microsatellite markers revealed a high level of genetic diversity in this population. Our results suggest that wild pear can be recommended for afforestation of areas affected by droughts and disturbed sites in Central Europe. It can be used to increase the heterogeneity of the landscape, e.g. by creation of forest ecotones and for planting along roads and field margins, especially considering the predicted climate change.
The aim of the studies was to compare the composition of soil bacterial metabiomes originating from urbanized areas and areas contaminated with hydrocarbons with those from agricultural soil and forest soil obtained from a protected wild-life park area. It should be noted that hydrocarbons are everywhere therefore bacteria capable of their utilization are present in every soil type. In the hydrocarbon-contaminated soil and in the soil of anthropogenic origin, the bacteria belonging to Gammaproteobacteria were dominant (28.4–36.6%), whereas in the case of agricultural soil and protected wild-life park soil their ratios decreased (22.8–23.0%) and were similar to that of Alphaproteobacteria. No statistically significant changes were observed in terms of the Operational Taxonomic Unit identified in the studies soils, however, based on the determined alpha-diversity it can be established that contaminated soils were characterized by lower biodiversity indices compared to agricultural and forest soils. Furthermore, the dioxygenase level was also evaluated in the studied soils, which are genes encoding crucial enzymes for the decomposition of mono- and polycyclic aromatic hydrocarbons during the biodegradation of diesel oil (PAHRHDαGN, PAHRHDαGP, xylE, Cat 2,3, ndoB). It was concluded that both the population structure of the soil metabiome and the number of genes crucial for biodegradation processes differed significantly between the soils. The level of analysed genes showed a similar trend, as their highest number in relations to genes encoding 16S RNA was determined in urban and hydrocarbon-contaminated soil.
One of the most informative sources which allow the drawing of far-reaching conclusions about the origins and phylogenetics of many species, including domestic animals and humans, is mitochondrial DNA (mtDNA). One of the important research targets should include the identification of similarities between wild and domestic species. The analysis involved the nucleotide sequences of mtDNA of wisent, auroch, bison, yak, bovine reference sequence (BRS) T3, T3a, T3b, T1, T1a, T1’2’3, T2, T3, T4, T5, Q, Q1, P, R, I1, and I2 bovine haplotypes. The non-coding D-loop regions were excluded from the evolutionary analysis and 15,419-bp coding sequences were used in the final dataset. Trees constructed on the basis of whole mitochondrial genomes or on total mtDNA coding sequences alignment were generally in agreement with previous studies on the Bovini tribe. American bison shows stronger maternal relationships to yak than to wisent. It seems that the isolation and divergence of wisent took place early, almost 2 to 1.6 million years ago. This appears to be compatible with the paleontological date, indicating Late Pleistocene speciation of Bison bonasus. The yak/bison mitochondrial transfer model is in agreement with our mutation analysis and phylogenetic tree. The bison/yak mutations were collected in the bison mitochondrial genome before the transfer. After the transfer, the parallel accumulation of unique mutations took place. According to our assessment, the transfer took place at about 700 ky. The characteristic feature of the wisent and bison evolution is the maintenance of mtDNA variability, despite the fact that both species underwent population bottlenecks. Our studies did not reveal any impact of these phenomena populations in the analyzed mitochondrial genomes.
Extinct aurochs (Bos primigenius), accepted as the ancestor of domestic cattle, was one of the largest wild animals inhabiting Europe, Asia and North Africa. The gradual process of aurochs extinction finished in Poland in 1627, were the last recorded aurochs, a female, died. Some aspects of cattle domestication history and the distribution of aurochs genetic material among modern cattle breeds still remain unclear. Analyses of ancient DNA (aDNA) from bone sample deliver new genetic information about extinct wild aurochs as well as modern cattle phylogeny. DNA was extracted from a fragment of aurochs fossil bone found in the Pisz Forest, Poland. The sample was radiocarbon-dated to about 1500 yBP. The aDNA was used for Whole Genome Amplification in order to form a DNA bank. Auroch mitochondrial DNA sequences were amplified using sets of 41 primers overlapping the whole mtDNA, cloned and sequenced. The sequence of the whole mitochondrial genome was reconstructed and deposed in GenBank [GenBank:JQ437479]. Based on the phylogenetic analyses of the Bovine mitochondrial genomes, a phylogenetic tree was created. As expected, the tree clearly shows that the mtDNA sequence of the analyzed PWA (Polish Wild Aurochs) individual belongs to haplogroup P. In the course of the comparative mtDNA analysis we identified 30 nucleotide marker positions for haplogroup P and nine unique PWA differences compared to the two remaining haplotype P representatives. Our analysis provides the next step to the reconstruction of the demographic history of this extinct but still exciting species.
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.