Organization and Variation Analysis of 5S rDNA in Different Ploidy-level Hybrids of Red Crucian Carp × Topmouth Culter

Through distant crossing, diploid, triploid and tetraploid hybrids of red crucian carp (Carassius auratus red var., RCC♀, Cyprininae, 2n = 100) × topmouth culter (Erythroculter ilishaeformis Bleeker, TC♂, Cultrinae, 2n = 48) were successfully produced. Diploid hybrids possessed 74 chromosomes with one set from RCC and one set from TC; triploid hybrids harbored 124 chromosomes with two sets from RCC and one set from TC; tetraploid hybrids had 148 chromosomes with two sets from RCC and two sets from TC. The 5S rDNA of the three different ploidy-level hybrids and their parents were sequenced and analyzed. There were three monomeric 5S rDNA classes (designated class I: 203 bp; class II: 340 bp; and class III: 477 bp) in RCC and two monomeric 5S rDNA classes (designated class IV: 188 bp, and class V: 286 bp) in TC. In the hybrid offspring, diploid hybrids inherited three 5S rDNA classes from their female parent (RCC) and only class IV from their male parent (TC). Triploid hybrids inherited class II and class III from their female parent (RCC) and class IV from their male parent (TC). Tetraploid hybrids gained class II and class III from their female parent (RCC), and generated a new 5S rDNA sequence (designated class I–N). The specific paternal 5S rDNA sequence of class V was not found in the hybrid offspring. Sequence analysis of 5S rDNA revealed the influence of hybridization and polyploidization on the organization and variation of 5S rDNA in fish. This is the first report on the coexistence in vertebrates of viable diploid, triploid and tetraploid hybrids produced by crossing parents with different chromosome numbers, and these new hybrids are novel specimens for studying the genomic variation in the first generation of interspecific hybrids, which has significance for evolution and fish genetics

The 5S rDNA family evolves through concerted and birth-and-death evolution in fish genomes: an example from freshwater stingrays

Background: Ribosomal 5S genes are well known for the critical role they play in ribosome folding and functionality. These genes are thought to evolve in a concerted fashion, with high rates of homogenization of gene copies. However, the majority of previous analyses regarding the evolutionary process of rDNA repeats were conducted in invertebrates and plants. Studies have also been conducted on vertebrates, but these analyses were usually restricted to the 18S, 5.8S and 28S rRNA genes. The recent identification of divergent 5S rRNA gene paralogs in the genomes of elasmobranches and teleost fishes indicate that the eukaryotic 5S rRNA gene family has a more complex genomic organization than previously thought. The availability of new sequence data from lower vertebrates such as teleosts and elasmobranches enables an enhanced evolutionary characterization of 5S rDNA among vertebrates.Results: We identified two variant classes of 5S rDNA sequences in the genomes of Potamotrygonidae stingrays, similar to the genomes of other vertebrates. One class of 5S rRNA genes was shared only by elasmobranches. A broad comparative survey among 100 vertebrate species suggests that the 5S rRNA gene variants in fishes originated from rounds of genome duplication. These variants were then maintained or eliminated by birth-and-death mechanisms, under intense purifying selection. Clustered multiple copies of 5S rDNA variants could have arisen due to unequal crossing over mechanisms. Simultaneously, the distinct genome clusters were independently homogenized, resulting in the maintenance of clusters of highly similar repeats through concerted evolution.Conclusions: We believe that 5S rDNA molecular evolution in fish genomes is driven by a mixed mechanism that integrates birth-and-death and concerted evolution

The 42nd Symposium Chromatographic Methods of Investigating Organic Compounds : Book of abstracts

The 42nd Symposium Chromatographic Methods of Investigating Organic Compounds : Book of abstracts. June 4-7, 2019, Szczyrk, Polan

Dobór optymalnych warunków konsolidacji plastycznej stopu AlSi11

In the present work, the optimal conditions for solid bonding of fragmented aluminum alloy were determined. The research was conducted on metal chips from the AlSi11 TM aluminum alloy after the turning process. The selection of proper bonding conditions was based on the results of tensile tests and surface quality analysis of as-extruded profiles. The extrusion process was conducted within a temperature range of 350–500°C, with a ram speed of 13 mm/s. Extrusion ratio λ was 25. As a reference material, a sample from the solid AlSi11 IM alloy has been extruded under the same conditions. The influence of temperature during direct extrusion on both maximum force and surface quality of obtained profiles has been determined. With reference to tensile test results, no significant influence of temperature on the mechanical properties has been noticed. Profiles extruded at 500°C were characterized by visible cracks on the surface, oriented perpendicular in the direction of extrusion. Moreover, surface flaws were also noticed in profiles extruded at 350°C. A tensile test revealed a strong relationship between the extrusion conditions and plasticity of solid bonded rods. A shiny and smooth surface was obtained only in profiles extruded at a temperature range of 400–450°C.W niniejszej pracy określono optymalne parametry procesu konsolidacji plastycznej drobnych form aluminium. Badaniu poddano wióry ze stopu AlSi11 (AK11 TM) otrzymane w procesie toczenia. Doboru optymalnych warunków konsolidacji plastycznej dokonano na podstawie własności mechanicznych oraz stanu powierzchni prasówki. Wyciskanie przeprowadzono na prasie współbieżnej w zakresie temperatur 350–500°C z prędkością stempla 13 mm/s. Stopień przerobu wynosił λ = 25. Jako materiał porównawczy wyciśnięto w tych samych warunkach materiał lity AlSi11 (AK11 IM) o tej samej masie. Określono wpływ temperatury wyciskania współbieżnego na siły maksymalne w procesie oraz jakość powierzchni przy użyciu SEM. Dodatkowo wyznaczono własności mechaniczne w próbie jednoosiowego rozciągania uzyskanych profili. Nie zaobserwowano znaczącego wpływu temperatury procesu na otrzymane własności wytrzymałościowe oraz plastyczne. Powierzchnia profili wyciskanych w 500°C charakteryzowała się prostopadłymi pęknięciami do kierunku wyciskania. Wady powierzchniowe zaobserwowano również w prętach wyciskanych w temperaturze 350°C. Badania wytrzymałościowe wykazały silny wpływ warunków konsolidacji na własności plastyczne profili otrzymanych z wiórów AlSi11. Pręty wyciśnięte w temperaturze 400°C i 450°C cechowały się gładką i błyszczącą powierzchnią

Wpływ szybkiej krystalizacji stopów aluminium z różną zawartością Si na własności mechaniczne oraz mikrostrukturę

Rapid solidification is a relatively new and effective way of producing ultrafine-grained UFG aluminum alloys with enhanced mechanical properties. Due to a significant cooling rate close to nearly 106 K/s, it is possible to obtain a material with grain size far below 100 nm. In the present study, RS aluminum alloys with an Si content in a range of 5–10 wt% were produced during melt spinning. As a result, materials in the form of ribbons were produced. The as-received flakes were subjected to cold pressing into cylindrical billets with a diameter of 40 mm. Hot extrusion of pre-compacted material was subsequently performed at a temperature of 450°C with a press ram speed of 3 mm/s and extrusion ratio of λ = 25. In this work, the influence of brittle phases on the mechanical properties of as-extruded rods will be examined. Both tensile and microhardness tests were performed in order to determine the mechanical properties of the obtained profiles. It has been shown that brittle-phase refinement during melt spinning significantly influences the mechanical properties of the tested materials.W wyniku szybkiej krystalizacji możliwe jest otrzymanie struktury drobnoziarnistej stopów aluminium o podwyższonych własnościach mechanicznych. Znaczna szybkość chłodzenia na poziomie 106 K/s umożliwia otrzymanie wielkości ziarna na poziomie 100 nm. W prezentowanych w pracy badaniach szybkiej krystalizacji poddano stopy aluminium o zawartości 5 oraz 10% wagowych Si. Otrzymane taśmy poddano wstępnemu prasowaniu na zimno do form brykietów o średnicy 40 mm. Proces wyciskania przeprowadzono w temperaturze 450°C z prędkością tłoka równą 3 mm/s. Stopień przerobu wynosił λ = 25. W niniejszym opracowaniu badano wpływ kruchych faz na własności mechaniczne wyciskanych prętów. W tym celu wykonano próbę jednoosiowego rozciągania oraz pomiary mikrotwardości otrzymanych profili. Wykazano znaczny wpływ rozdrobnienia kruchych faz podczas szybkiej krystalizacji na własności mechaniczne badanych materiałów

Improving the Processing and Analysis Workflow of Adaptive Optics Retinal Imaging

Using a few custom and commercial programs to speed up image montaging and selecting regions of interest when processing and analyzing images of the retina taken with and adaptive optics scanning light ophthalmoscope

Study on side structure resistance to ship-ship collisions

Double hull (DH) tankers may be more effective than single hull (SH) tankers in pollution prevention because they have a second barrier, the inner skin, to oil outflow in the event of side damage. The actual effect of DHs calls for quantitative study. This paper presents a comparative study on the side structure resistance to collisions. A DH Aframax tanker and an SH Aframax tanker of similar size were selected for the study. The two vessels were assumed to be struck by a same bulbous bow in different locations and angles. The bow was assumed to be rigid and different non-linear materials and contact models were considered for the struck tankers based on the original designs. The DH tanker was found to be superior to the SH tanker in relation to resistance to side structural damage. Finally, by using the simulation results, the distribution of damage extents for DH tankers is proposed based on the historical damage extents, which are mainly for SH tankers