Repeated reunions and splits feature the highly dynamic evolution of 5S and 35S ribosomal RNA genes (rDNA) in the Asteraceae family

<p>Abstract</p> <p>Background</p> <p>In flowering plants and animals the most common ribosomal RNA genes (rDNA) organisation is that in which 35S (encoding 18S-5.8S-26S rRNA) and 5S genes are physically separated occupying different chromosomal loci. However, recent observations established that both genes have been unified to a single 35S-5S unit in the genus <it>Artemisia </it>(Asteraceae), a genomic arrangement typical of primitive eukaryotes such as yeast, among others. Here we aim to reveal the origin, distribution and mechanisms leading to the linked organisation of rDNA in the Asteraceae by analysing unit structure (PCR, Southern blot, sequencing), gene copy number (quantitative PCR) and chromosomal position (FISH) of 5S and 35S rRNA genes in ~200 species representing the family diversity and other closely related groups.</p> <p>Results</p> <p>Dominant linked rDNA genotype was found within three large groups in subfamily Asteroideae: tribe Anthemideae (93% of the studied cases), tribe Gnaphalieae (100%) and in the "Heliantheae alliance" (23%). The remaining five tribes of the Asteroideae displayed canonical non linked arrangement of rDNA, as did the other groups in the Asteraceae. Nevertheless, low copy linked genes were identified among several species that amplified unlinked units. The conserved position of functional 5S insertions downstream from the 26S gene suggests a unique, perhaps retrotransposon-mediated integration event at the base of subfamily Asteroideae. Further evolution likely involved divergence of 26S-5S intergenic spacers, amplification and homogenisation of units across the chromosomes and concomitant elimination of unlinked arrays. However, the opposite trend, from linked towards unlinked arrangement was also surmised in few species indicating possible reversibility of these processes.</p> <p>Conclusions</p> <p>Our results indicate that nearly 25% of Asteraceae species may have evolved unusual linked arrangement of rRNA genes. Thus, in plants, fundamental changes in intrinsic structure of rDNA units, their copy number and chromosomal organisation may occur within relatively short evolutionary time. We hypothesize that the 5S gene integration within the 35S unit might have repeatedly occurred during plant evolution, and probably once in Asteraceae.</p

Technical Diagnostics of Tank Cannon Smooth Barrel Bore and Ramming Device

The technical diagnostics of 125 mm tank cannon 2A46 smooth barrel and ramming devices are discussed respectively. Focuses on barrel diagnostics and suggests new procedures based on reconstructed BG20 Gun Barrel Bore Gauge System, measuring internal diameter of the barrel bore. The new system measures throughout the whole barrel bore the inner diameter not only at the beginning of barrel bore as it was usually measured before. Different nature of barrel wear was revealed between barrels firing sub-calibre and high explosive projectiles. A method for ramming device diagnostics is presented. An accurate method was proposed, determining projectile extraction force from barrel, as one of the main ramming device parameters for weapons that are used in all areas of armed forces. Results are based on experimental methods assessing the extraction forces from barrel after projectile loading. These tests were performed as a series of tests with consequent technical diagnostics according to the new Czech Defence Standards (derived from NATO standards). The results are presented as the new methodologies for diagnostics of 125 mm barrel 2A46 and ramming devices of tank T-72 for use by technical logistic units in the Czech Republic Armed Forces

of the Moravian Karst Protected Landscape Area

Abstract Host traits and phylogeny can determine infection risk by driving pathogen transmission and its ability to infect new hosts. Predicting such risks is critical when designing disease mitigation strategies, and especially as regards wildlife, where intensive management is often advocated or prevented by economic and/or practical reasons. We investigated Pseudogymnoascus [Geomyces] destructans infection, the cause of white-nose syndrome (WNS), in relation to chiropteran ecology, behaviour and phylogenetics. While this fungus has caused devastating declines in North American bat populations, there have been no apparent population changes attributable to the disease in Europe. We screened 276 bats of 15 species from hibernacula in the Czech Republic over 2012 and 2013, and provided histopathological evidence for 11 European species positive for WNS. With the exception of Myotis myotis, the other ten species are all new reports for WNS in Europe. Of these, M. emarginatus, Eptesicus nilssonii, Rhinolophus hipposideros, Barbastella barbastellus and Plecotus auritus are new to the list of P. destructans-infected bat species. While the infected species are all statistically phylogenetically related, WNS affects bats from two suborders. These are ecologically diverse and adopt a wide range of hibernating strategies. Occurrence of WNS in distantly related bat species with diverse ecology suggests that the pathogen may be a generalist and that all bats hibernating within the distribution range of P. destructans may be at risk of infection

Effect of Seven Newly Synthesized and Currently Available Oxime Cholinesterase Reactivators on Cyclosarin-Intoxicated Rats

Seven new oxime-based acetylcholinesterase reactivators were compared with three currently available ones (obidoxime, trimedoxime, HI-6) for their ability to lessen cholinesterase inhibition in blood and brain of cyclosarin-treated rats. Oximes were given at doses of 5% their LD50 along with 21 mg/kg atropine five min before the LD50 of cyclosarin (120 ug/kg) was administered. Blood and brain samples were collected 30 minutes later. The greatest difference between acetylcholinesterase inhibition in blood of cyclosarin-treated rats was found after administration of HI-6 (40%), compared to 22% for trimedoxime and 6% for obidoxime. Only two of the seven newly synthesized oximes had any effect (K203 at 7%, K156 at 5%). Effective oximes against cyclosarin-inhibited plasma butyrylcholinesterase were HI-6 (42%), trimedoxime (11%), and K156 (4%). The oximes were less effective in brain than in blood, with reactivation values for HI-6 30% against acetylcholinesterase and 10% against butyrylcholinesterase. Values for newly synthesized oximes were less than 10% for K206, K269 and K203

Independent, Rapid and Targeted Loss of Highly Repetitive DNA in Natural and Synthetic Allopolyploids of Nicotiana tabacum

Allopolyploidy (interspecific hybridisation and polyploidy) has played a significant role in the evolutionary history of angiosperms and can result in genomic, epigenetic and transcriptomic perturbations. We examine the immediate effects of allopolyploidy on repetitive DNA by comparing the genomes of synthetic and natural Nicotiana tabacum with diploid progenitors N. tomentosiformis (paternal progenitor) and N. sylvestris (maternal progenitor). Using next generation sequencing, a recently developed graph-based repeat identification pipeline, Southern blot and fluorescence in situ hybridisation (FISH) we characterise two highly repetitive DNA sequences (NicCL3 and NicCL7/30). Analysis of two independent high-throughput DNA sequencing datasets indicates NicCL3 forms 1.6–1.9% of the genome in N. tomentosiformis, sequences that occur in multiple, discontinuous tandem arrays scattered over several chromosomes. Abundance estimates, based on sequencing depth, indicate NicCL3 is almost absent in N. sylvestris and has been dramatically reduced in copy number in the allopolyploid N. tabacum. Surprisingly elimination of NicCL3 is repeated in some synthetic lines of N. tabacum in their forth generation. The retroelement NicCL7/30, which occurs interspersed with NicCL3, is also under-represented but to a much lesser degree, revealing targeted elimination of the latter. Analysis of paired-end sequencing data indicates the tandem component of NicCL3 has been preferentially removed in natural N. tabacum, increasing the proportion of the dispersed component. This occurs across multiple blocks of discontinuous repeats and based on the distribution of nucleotide similarity among NicCL3 units, was concurrent with rounds of sequence homogenisation

From Immunosuppression to Immunomodulation: Current Principles and Future Strategies

Over the last few decades tremendous progress has been made in understanding the mechanisms of immune responses. This progress has also lead to a more detailed knowledge of the processes leading to the loss of self-tolerance and self-tissue destruction in the case of autoimmune diseases, the effector mechanism involved in transplant allograft rejection as well as on the driving factors in exacerbated inflammatory disorders. Despite this progress, the challenge still remains to selectively interfere with immune responses responsible for autoimmunity or transplant rejection while keeping an intact response to infectious agents. Such a selective interference has to date been difficult to achieve as highlighted by the fact that an overall increased risk for infections and malignancy continue to be the most frequent side effects of the currently used immunosuppressive principles. Nevertheless, although discovered several decades ago many of the “first generation” immunosuppressive principles such as steroids, Methotrexate and Cyclosporine A are still in clinical use, demonstrating the therapeutic value of these drugs for the patients that are in need. In this review the author describes the mode of action of the currently most used immunosuppressive agents (not attempting to cover all principles that are available) and expands on recent activities in the discovery and development of novel immune-modulatory principles

The search for novel adjuvants for early life vaccinations: can "danger" motifs show us the way?

Potent but safe adjuvants are required to circumvent the many limitations of the newborn immune system to induce rapidly effective and long lasting immunity to subunit vaccines. By the use of pattern recognition receptors, antigen-presenting cells (APC) can very efficiently be activated by "danger" motifs expressed by various pathogens. APC activated by "danger" motifs, such as immunostimulatory sequences of bacterial DNA, can not only transmit the activation signal from the innate immunity to the adaptive compartment, but also shape the antigen-specific immune responses. Molecules or compounds expressing "danger" motifs could, therefore, be considered for use as adjuvants for subunit vaccines. In this review, the authors discuss the promises and potential drawbacks that such novel adjuvants could hold for their use in experimental and clinical early life vaccinations

Induction of neonatal TH1 and CTL responses by live viral vaccines: a role for replication patterns within antigen presenting cells?

Failure to generate CTL responses in early life has been linked to the preferential maturation of CD4 T cells into TH2 rather than TH1 cells in response to some, but not other, antigenic stimulations. Here, we provide preliminary evidence for the role of the viral replication pattern in the shaping of neonatal cellular responses to live viral vaccines. Neonatal and early life immunization with live attenuated Sendai virus vaccine led to the induction of IgG2a antibodies and cytotoxic responses as efficiently as immunization of adult animals. Similarly, although early life immunization with live attenuated measles virus led to preferential TH2 polarization of T cells compared with adult primed animals, it allowed the induction of CTL responses which had not been observed following immunization with a live recombinant canarypox vector. Thus, conversely to a non-replicating canarypox recombinant vaccine expressing the measles haemagglutonin, viral vaccines with limited but present replication capacity appear capable of activating neonatal antigen presenting cells to trigger TH1 and CTL responses, as recently observed for DNA vaccines