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

Radiological response to nivolumab in patients with hepatocellular carcinoma: A multicenter analysis of real-life practice

Background and aims: Immune-checkpoint inhibitors are effective in many advanced tumors. However, there is scarce information regarding the radiological response to these agents in hepatocellular carcinoma outside clinical trials. We aimed to describe the radiological response in a retrospective cohort of hepatocellular carcinoma patients treated with nivolumab and to analyze the radiological evolution according to tumor response at first post-treatment radiological assessment. Methods: We reviewed pre-treatment and post-treatment images (CT or MRI) obtained at different time-points in patients with hepatocellular carcinoma treated with nivolumab outside clinical trials at seven Spanish centers, assessing the response according to RECIST 1.1 and iRECIST and registering atypical responses. We also analyzed the imaging findings on subsequent assessments according to tumor status on the first posttreatment imaging assessment. Results: From the 118 patients with hepatocellular carcinoma treated with nivolumab, we finally analyzed data from 31 patients (71 % Child-Pugh A; 74 % BCLC-C). Median follow-up was 8.39 months [IQR 5.00-10.92]; median overall survival was 12.82 months (95 %CI 10.92-34.79). According to RECIST 1.1, the objective response rate was 16 % and according to iRECIST, the objective response rate was 22.6 %. Findings at the first post-treatment assessment varied, showing stable disease in 44.8 % of patients; findings during follow-up also varied widely, including 4 hyperprogressions and 3 pseudoprogressions. Conclusion: Imaging findings during nivolumab treatment are heterogeneous between and within patients. Progression of disease does not always signify treatment failure, and surrogate end-points may not reflect survival outcomes, making the management of hepatocellular carcinoma patients under immunotherapy challengin

(Vol. 06, 2003-12) A New Species of Galinsoga (Asteraceae: Millerieae: Galinsoginae) from Northwestern Mexico

Galinsoga crozierae from the state of Durango, northwest Mexico is described and its salient morphological features compared to those of other species in the genus.Billie L. Turner Plant Resources Cente

(Vol. 01, 1998-05) A New Species of Ageratina (Asteraceae: Eupatorieae) from Northwestern Oaxaca

Fieldwork in connection with the project to document the flora of the Mixteca Alta region of the state of Oaxaca has resulted in the discovery of a new species in the district of Juxtlahuaca, Ageratina juxtlahuacensis. Its distinctive morphological traits are discussed and compared to putative sister species.Billie L. Turner Plant Resources Cente

(Vol. 06, 2003-12) Primers for PCR Amplification of Asteraceae Chloroplast DNA

Primers for the amplification and sequencing of DNA fragments from chloroplast genes and non-coding regions are provided to facilitate molecular phylogenetic studies aimed at building a tree-of-life for the Asteraceae. The primers reported here have been extensively tested and some empirical guidelines are included to facilitate their use.Billie L. Turner Plant Resources Cente

Contribution to the genome size knowledge of New World species from the Heliantheae alliance (Asteraceae)

This article contributes first genome size assessments by flow cytometry for 16 species, 12 genera, and 3 tribes from family Asteraceae, mostly belonging to the Heliantheae alliance, an assembly of 13 tribes from subfamily Asteroideae with a large majority of its species in the New World. Most genome sizes are accompanied by their own chromosome counts, confirming in most cases, although not all, previous counts for the species, and revealing possible cases of unknown dysploidy or polyploidy for certain taxa. The data contribute to the pool of knowledge on genome size and chromosome numbers in the family Asteraceae and will further allow deeper studies and a better understanding on the role of dysploidy in the evolution of the Heliantheae alliance. However, we still lack data for tribes Chaenactideae, Neurolaeneae, Polymnieae, and Feddeeae (the latter, monospecific) to complete the alliance representation.This work was supported by the Dirección General de Investigación Científica y Técnica, Government of Spain (CGL2016-75694-P) and the Generalitat de Catalunya, Government of Catalonia (>Ajuts a grups de recerca consolidats> 2014SGR514). SG benefitted from a Ramón y Cajal contract from the Government of Spain (RYC-2014-16608)

Phylogenetic and biogeographic approach to genus flourensia (asteraceae heliantheae)

The Neotropical genus Flourensia DC. (Asteraceae, Heliantheae) comprises 32 taxa with two diversitycenters one in arid zones of southern South America and one in northern Mexico-southern USA. Thesame disjunction is found in several Angiosperm taxa (e,g., [Larrea (Zygophyllaceae), Prosopis,Prosopidastrum, Hoffmannseggia (Fabaceae), and Distichlis (Poaceae)] which has fuelled the discussionas to whether the flora of these biotas arose by vicariance or long distance dispersal. Phylogenetic studiesavailable for some of the groups support the latter and furthermore suggest that long distance dispersalmay have happened repeatedly in some of these. In Flourensia, the presence of several narrow endemicspecies in the northern Argentina suggests limited dispersal ability. Analyzing how and when Flourensiaobtained its disjunct distribution and diversified in arid regions of both southern and northern America isthe aim of the present study. In South America, Flourensia species mainly occupy environments of theinter-Andean dry valleys from the southern depression of Huancabamba in Peru to central Argentina, withmost of the species distributed in northern Argentina. Based on our parsimony analysis of Flourensiainferred from nuclear ITS and plastid trnL-F sequences, we study the geographical distributions of allspecies to determine whether the current disjunct distribution of the genus is due to one or several events.Fil: Guerrero Ospina, Juan Camilo. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; ArgentinaFil: Freire, Susana Edith. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; ArgentinaFil: Scataglini, María Amalia. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; ArgentinaFil: Panero, José L. University Station; Estados Unidos. University of Texas; Estados UnidosFil: Correa, Carolina Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - Tucumán. Unidad Ejecutora Lillo; ArgentinaFil: Aagesen, Lone. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; ArgentinaXXXV Annual Meeting of the Willi Hennig SocietyCiudad Autónoma de Buenos AriesArgentinaWilli Hennig Societ