Rapid Chromosome Evolution in Recently Formed Polyploids in Tragopogon (Asteraceae)

Polyploidy, frequently termed "whole genome duplication", is a major force in the evolution of many eukaryotes. Indeed, most angiosperm species have undergone at least one round of polyploidy in their evolutionary history. Despite enormous progress in our understanding of many aspects of polyploidy, we essentially have no information about the role of chromosome divergence in the establishment of young polyploid populations. Here we investigate synthetic lines and natural populations of two recently and recurrently formed allotetraploids Tragopogon mirus and T. miscellus (formed within the past 80 years) to assess the role of aberrant meiosis in generating chromosomal/genomic diversity. That diversity is likely important in the formation, establishment and survival of polyploid populations and species.Applications of fluorescence in situ hybridisation (FISH) to natural populations of T. mirus and T. miscellus suggest that chromosomal rearrangements and other chromosomal changes are common in both allotetraploids. We detected extensive chromosomal polymorphism between individuals and populations, including (i) plants monosomic and trisomic for particular chromosomes (perhaps indicating compensatory trisomy), (ii) intergenomic translocations and (iii) variable sizes and expression patterns of individual ribosomal DNA (rDNA) loci. We even observed karyotypic variation among sibling plants. Significantly, translocations, chromosome loss, and meiotic irregularities, including quadrivalent formation, were observed in synthetic (S(0) and S(1) generations) polyploid lines. Our results not only provide a mechanism for chromosomal variation in natural populations, but also indicate that chromosomal changes occur rapidly following polyploidisation.These data shed new light on previous analyses of genome and transcriptome structures in de novo and establishing polyploid species. Crucially our results highlight the necessity of studying karyotypes in young (<150 years old) polyploid species and synthetic polyploids that resemble natural species. The data also provide insight into the mechanisms that perturb inheritance patterns of genetic markers in synthetic polyploids and populations of young natural polyploid species

Ibrutinib in the Treatment of Refractory Chronic Lymphocytic Leukemia

Background & Aims. This paper presents the results of the observational study of ibrutinib in patients with chronic lymphocytic leukemia (CLL), conducted in SP Botkin Municipal Clinical Hospital. The main objective was the analysis of complications of ibrutinib and identification of factors, influencing the dosage regimen; the secondary objective was the estimation of the total response to treatment, event-free and overall survival. Materials & Methods. The study included 96 patients with CLL with indications for ibrutinib therapy. The median age was 64,9 years (range 32–91 years), the study population consisted of 69 (72 %) men and 27 (28 %) women. The condition of 25 (26 %) patients according to the ECOG scale was of > 3 points. The disease of stage C were diagnosed in 36 (37 %) patients . Deletion of 17p/TP53 mutations were detected in 29 (33 %) of 87 patients. Seventy patients had refractory CLL. The median of the number of the lines of the previous therapy was 3 (range 1–9). Adverse events were assessed in accordance with the CTCAE criteria, version 4.0; the bleeding severity was evaluated using ITP-specific bleeding score; hematological complications were classified according to the recommendations of IWCLL-2008. Results. Ibrutinib was administered at a dosage of 420 mg per day daily until progression or intolerable toxicity. The median duration of ibrutinib therapy was 10.3 months. Ibrutinib was shown to have moderate toxicity, mostly of grade I or II. The bleeding was the most frequent complication. Of the hematological complications, thrombocytopenia was the most common (35 %); neutropenia grade III) developed in 26 % of patients. The treatment response was assessed in 92 patients. The overall response to treatment was 89 %. Complete remission, partial remission and partial remission with lymphocytosis were achieved in 4 (4 %), 57 (62 %), and 21 (23 %) patients, respectively. The event-free survival and overall survival by the month 10 was 90 % and 91 %, respectively. For this observation period, ECOG status and the number of the lines of therapy prior to ibrutinib had the prognostic value. Conclusion. Ibrutinib was shown to have high efficiency in relapsed/refractory forms of CLL. The nature of the ibrutinib toxicity is fundamentally different from that of the conventional chemotherapy. The frequency of ibrutinib therapy complications and patients’ non-compliance depends on the intensity of the previous treatment of CLL. Despite a short observation period, it can be concluded that ibrutinib had the greatest impact on the patient’s quality of life when administered for the first relapse. The low toxicity of ibrutinib is likely to allow the combination with other antitumor agents

X-Ray Spectroscopy of Stars

(abridged) Non-degenerate stars of essentially all spectral classes are soft X-ray sources. Low-mass stars on the cooler part of the main sequence and their pre-main sequence predecessors define the dominant stellar population in the galaxy by number. Their X-ray spectra are reminiscent, in the broadest sense, of X-ray spectra from the solar corona. X-ray emission from cool stars is indeed ascribed to magnetically trapped hot gas analogous to the solar coronal plasma. Coronal structure, its thermal stratification and geometric extent can be interpreted based on various spectral diagnostics. New features have been identified in pre-main sequence stars; some of these may be related to accretion shocks on the stellar surface, fluorescence on circumstellar disks due to X-ray irradiation, or shock heating in stellar outflows. Massive, hot stars clearly dominate the interaction with the galactic interstellar medium: they are the main sources of ionizing radiation, mechanical energy and chemical enrichment in galaxies. High-energy emission permits to probe some of the most important processes at work in these stars, and put constraints on their most peculiar feature: the stellar wind. Here, we review recent advances in our understanding of cool and hot stars through the study of X-ray spectra, in particular high-resolution spectra now available from XMM-Newton and Chandra. We address issues related to coronal structure, flares, the composition of coronal plasma, X-ray production in accretion streams and outflows, X-rays from single OB-type stars, massive binaries, magnetic hot objects and evolved WR stars.Comment: accepted for Astron. Astrophys. Rev., 98 journal pages, 30 figures (partly multiple); some corrections made after proof stag

Biological function in the twilight zone of sequence conservation

Abstract Strong DNA conservation among divergent species is an indicator of enduring functionality. With weaker sequence conservation we enter a vast ‘twilight zone’ in which sequence subject to transient or lower constraint cannot be distinguished easily from neutrally evolving, non-functional sequence. Twilight zone functional sequence is illuminated instead by principles of selective constraint and positive selection using genomic data acquired from within a species’ population. Application of these principles reveals that despite being biochemically active, most twilight zone sequence is not functional