Temat: RNA recombination - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Two types of non-homologous RNA recombination in brome mosaic virus
Autorzy:: Alejska, Magdalena
Malinowska, Nelli
Urbanowicz, Anna
Figlerowicz, Marek
Tematy:: non-homologous RNA recombination
site-specific RNA recombination
heteroduplex-mediated RNA recombination
brome mosaic virus; Pokaż więcej
Wydawca:: Polskie Towarzystwo Biochemiczne
Powiązania:: https://bibliotekanauki.pl/articles/1041326.pdf Link otwiera się w nowym oknie
Opis:: Non-homologous RNA recombination is a process enabling the exchange of genetic material between various (related or unrelated) RNA-based viruses. Despite extensive investigations its molecular mechanism remains unclear. Studies on genetic recombination in brome mosaic virus (BMV) have shown that local hybridization between genomic RNAs induces frequent non-homologous crossovers. A detailed analysis of recombinant structures suggested that local complementary regions might be involved in two types of non-homologous recombination in BMV: site-specific and heteroduplex-mediated. To verify the above hypothesis and better recognize the mechanism of the phenomenon studied we have tested how the putative types of recombination are affected by a specific mutation in the BMV polymerase gene or by changes in RNA structure. The experiments undertaken revealed substantial differences between site-specific and heteroduplex-mediated recombination, indicating that they occur according to different mechanisms. The former can be classified as homology-assisted, and the latter as homology-independent. In addition to local RNA/RNA hybridization, short regions of homology are required for site-specific crossovers to occur. They are most efficiently mediated if one homologous sequence is located at the beginning of and the second just before a double-stranded region. At present it is difficult to state what is the mechanism of heteroduplex-mediated recombination. Earlier it was postulated that strong RNA/RNA interaction enforces template switching by the viral replicase. There are, however, several observations questioning this model and indicating that some other factors, which are still unknown, may influence heteroduplex-mediated crossovers.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: How RNA viruses exchange their genetic material.
Autorzy:: Alejska, Magdalena
Kurzyńska-Kokorniak, Anna
Broda, Magdalena
Kierzek, Ryszard
Figlerowicz, Marek
Tematy:: RNA recombination
RNA structure
viral replicase
RNA viruses
retroviruses; Pokaż więcej
Wydawca:: Polskie Towarzystwo Biochemiczne
Powiązania:: https://bibliotekanauki.pl/articles/1044130.pdf Link otwiera się w nowym oknie
Opis:: One of the most unusual features of RNA viruses is their enormous genetic variability. Among the different processes contributing to the continuous generation of new viral variants RNA recombination is of special importance. This process has been observed for human, animal, plant and bacterial viruses. The collected data reveal a great susceptibility of RNA viruses to recombination. They also indicate that genetic RNA recombination (especially the nonhomologous one) is a major factor responsible for the emergence of new viral strains or species. Although the formation and accumulation of viral recombinants was observed in numerous RNA viruses, the molecular basis of this phenomenon was studied in only a few viral species. Among them, brome mosaic virus (BMV), a model (+)RNA virus offers the best opportunities to investigate various aspects of genetic RNA recombination in vivo. Unlike any other, the BMV-based system enables homologous and nonhomologous recombination studies at both the protein and RNA levels. As a consequence, BMV is the virus for which the structural requirements for genetic RNA recombination have been most precisely established. Nevertheless, the previously proposed model of genetic recombination in BMV still had one weakness: it could not really explain the role of RNA structure in nonhomologous recombination. Recent discoveries concerning the latter problem give us a chance to fill this gap. That is why in this review we present and thoroughly discuss all results concerning nonhomologous recombination in BMV that have been obtained until now.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Low recombination activity of R region located at both ends of the HIV-1 genome
Autorzy:: Urbanowicz, Anna
Kurzyńska-Kokorniak, Anna
Jankowska, Anna
Alejska, Magdalena
Figlerowicz, Marek
Tematy:: copy-choice mechanism
template switching
homologous RNA recombination
strand transfer
R region
RNA virus
retrovirus; Pokaż więcej
Wydawca:: Polskie Towarzystwo Biochemiczne
Powiązania:: https://bibliotekanauki.pl/articles/1039669.pdf Link otwiera się w nowym oknie
Opis:: Although two strand transfer events are indispensable for the synthesis of double-stranded DNA and establishing HIV-1 infection, the molecular basis of these phenomena is still unclear. The first obligatory template switching event occurs just at the beginning of the virus replication cycle and involves two copies of the 97-nucleotide long R region, located one each at the both ends of the HIV-1 genome (HIV-1 R). Thus, one can expect that the molecular mechanism of this process is similar to the mechanism of homologous recombination which operates in RNA viruses. To verify the above-mentioned hypothesis, we attempted to assess the recombination activity of HIV-1 R. To this end, we tested in vitro, how effectively it induces template switching by HIV-1 RT in comparison with another well-characterized sequence supporting frequent homologous crossovers in an unrelated virus (R region derived from Brome mosaic virus - BMV R). We also examined if the RNA sequences neighboring HIV-1 R influence its recombination activity. Finally, we tested if HIV-1 R could cause BMV polymerase complex to switch between RNA templates in vivo. Overall, our results have revealed a relatively low recombination activity of HIV-1 R as compared to BMV R. This observation suggests that different factors modulate the efficiency of the first obligatory strand transfer in HIV-1 and the homology-driven recombination in RNA viruses.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Co-inoculation with two non-infectious cDNA copies of potato spindle tuber viroid (PSTVd) leads to the appearance of novel fully infectious variants.
Autorzy:: Podstolski, Wojciech
Góra-Sochacka, Anna
Zagórski, Włodzimierz
Tematy:: non-coding RNA
viroid
circular RNA
PSTVd
recombination; Pokaż więcej
Wydawca:: Polskie Towarzystwo Biochemiczne
Powiązania:: https://bibliotekanauki.pl/articles/1041466.pdf Link otwiera się w nowym oknie
Opis:: Potato spindle tuber viroid (PSTVd) is one of the smallest (about 360 nt) infectious plant agents. It is composed of a single-stranded circular non-coding RNA molecule. In the course of previous passage experiments with two intermediate PSTVd variants I2 and I4, three non-infectious clones (I2-50, I4-37 and I4 VI-17) were found. When inoculated separately as cDNAs on tomato "Rutgers" test plants these variants did not induce any visible disease symptoms and did not produce progeny. The presence of such non-infectious variants raises several questions about their origin and biology and to answer them, mixed co-infections with cDNA copies of two non-infectious variants (I2-50, I4-37) were performed. PSTVd infection was observed in seven out of 30 inoculated plants. The progeny isolated from three separate plants contained novel variants, together with the parental I2 and I4 sequences. It is conceivable that the appearance of repaired PSTVd molecules, clearly capable of cell-to-cell movement leading to the systemic infection, results from recombination events. An analysis of the recombinant molecules and comparison with databases identified the specific sites responsible for the restricted infectivity of the I2-50 and I4-37 PSTVd variants. In parallel experiments in which (+) strand PSTVd infectious transcripts were used, no recombinants were observed, and the original I2-50 and I4-37 non-infectious sequences were not detected in the progeny.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Regulatory mechanisms of gene expression: complexity with elements of deterministic chaos
Autorzy:: Jura, Jolanta
Węgrzyn, Paulina
Jura, Jacek
Koj, Aleksander
Tematy:: linear and nonlinear responses
somatic recombination
biallelic expression
alternative splicing
epigenetics
RNA editing
monoallelic expression; Pokaż więcej
Wydawca:: Polskie Towarzystwo Biochemiczne
Powiązania:: https://bibliotekanauki.pl/articles/1041263.pdf Link otwiera się w nowym oknie
Opis:: Linear models based on proportionality between variables have been commonly applied in biology and medicine but in many cases they do not describe correctly the complex relationships of living organisms and now are being replaced by nonlinear theories of deterministic chaos. Recent advances in molecular biology and genome sequencing may lead to a simplistic view that all life processes in a cell, or in the whole organism, are strictly and in a linear fashion controlled by genes. In reality, the existing phenotype arises from a complex interaction of the genome and various environmental factors. Regulation of gene expression in the animal organism occurs at the level of epigenetic DNA modification, RNA transcription, mRNA translation, and many additional alterations of nascent proteins. The process of transcription is highly complicated and includes hundreds of transcription factors, enhancers and silencers, as well as various species of low molecular mass RNAs. In addition, alternative splicing or mRNA editing can generate a family of polypeptides from a single gene. Rearrangement of coding DNA sequences during somatic recombination is the source of great variability in the structure of immunoglobulins and some other proteins. The process of rearrangement of immunoglobulin genes, or such phenomena as parental imprinting of some genes, appear to occur in a random fashion. Therefore, it seems that the mechanism of genetic information flow from DNA to mature proteins does not fit the category of linear relationship based on simple reductionism or hard determinism but would be probably better described by nonlinear models, such as deterministic chaos.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Regulatory mechanisms of gene expression : complexity with elements of deterministic chaos
Dostawca treści:: Repozytorium Uniwersytetu Jagiellońskiego

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Skocz do pozycji: 7.

Tytuł:: Zmienność wirusów - przyczyny i skutki
Genetic viral variability - causes and effects
Autorzy:: Gliński, Zdzisław
Żmuda, Andrzej
Tematy:: wirusologia
wirusy
wirusy RNA
wirus grypy
wirus dengi
wirus zika
wirus Zachodniego Nilu
koronawirusy
przyczyny
mutacje
rekombinacja
skutki
wirus wścieklizny
zmienność genetyczna
RNA viruses
genetic variability
mutation
recombination; Pokaż więcej
Wydawca:: Krajowa Izba Lekarsko-Weterynaryjna
Powiązania:: https://bibliotekanauki.pl/articles/22181107.pdf Link otwiera się w nowym oknie
Opis:: Viruses are endowed with a great ability to adapt to different environments. It means altering their cellular tropism and crossing host animal species barriers. The basis of their evolutionary success lies in subtle genetic changes through mutations and major genetic changes through recombination and nucleotide substitution. Genetic recombination is one of the primary processes that produce the genetic diversity upon which natural selection acts. RNA viruses have a great potential for genetic variation, rapid evolution and adaptation. Since influenza viruses have segmented genome, the reassortment is among important mechanisms for generation of new hybrid strains and/or subtypes. The modifications of viral RNA genome are frequently dependent on RNA polymerases erroneous action during replication, on the evolutionary pressure, on the novel environment of the host, the immune pressure, or antiviral drugs pressure. Shift to the new host species and virus transmission by insect vectors induced changes due to positive selection of variants with higher fitness for host-virus or vector-virus interactions. This article covers basic aspects of genetic diversity mechanisms of mutation and recombination of selected RNA viruses. The Influenza virus, Denga, Zika, West Nile, Rabies and SARS‑CoV-2 are just among several examples of virus genetic variations, that influence rapid evolution of viral diseases, and make design of reliable vaccine quite difficult.
Dostawca treści:: Biblioteka Nauki

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