A universal karyotypic system for hexaploid and diploid Avena species brings oat cytogenetics into the genomics era.

BACKGROUND: The identification of chromosomes among Avena species have been studied by C-banding and in situ hybridization. However, the complicated results from several cytogenetic nomenclatures for identifying oat chromosomes are often contradictory. A universal karyotyping nomenclature system for precise chromosome identification and comparative evolutionary studies would be essential for genus Avena based on the recently released genome sequences of hexaploid and diploid Avena species. RESULTS: Tandem repetitive sequences were predicted and physically located on chromosomal regions of the released Avena sativa OT3098 genome assembly v1. Eight new oligonucleotide (oligo) probes for sequential fluorescence in situ hybridization (FISH) were designed and then applied for chromosome karyotyping on mitotic metaphase spreads of A. brevis, A. nuda, A. wiestii, A. ventricosa, A. fatua, and A. sativa species. We established a high-resolution standard karyotype of A. sativa based on the distinct FISH signals of multiple oligo probes. FISH painting with bulked oligos, based on wheat-barley collinear regions, was used to validate the linkage group assignment for individual A. sativa chromosomes. We integrated our new Oligo-FISH based karyotype system with earlier karyotype nomenclatures through sequential C-banding and FISH methods, then subsequently determined the precise breakage points of some chromosome translocations in A. sativa. CONCLUSIONS: This new universal chromosome identification system will be a powerful tool for describing the genetic diversity, chromosomal rearrangements and evolutionary relationships among Avena species by comparative cytogenetic and genomic approaches.

Karyotype analysis of three species of Corydoras (Siluriformes: Callichthyidae) from southern Brazil: rearranged karyotypes and cytotaxonomy

The genus Corydoras comprises a diversity of species with different diploid numbers. We compared cytogenetic data among Corydoras species from different rivers of the Ponta Grossa Arch region in southern Brazil. Corydoras ehrhardti and C. aff. paleatus have a similar karyotype formula and the same diploid number (2n = 44). Corydoras lacrimostigmata has a higher diploid number, with 2n = 58 chromosomes. Fluorescence in situ hybridization using 5S and 18S ribosomal DNA probes suggests that these ribosomal DNA sequences are involved in chromosomal rearrangements in these Corydoras species. 5S rDNA is a chromosomal marker that is considered to be unique to the species analyzed in this study. Signals of interstitial telomeric sites are seen in a chromosome pair of C. lacrimostigmata, suggesting chromosomal rearrangements via fusions or translocations. This study revealed that C. ehrhardti and C. aff. paleatus have exclusive chromosomal markers associated with chromosome differentiation, which we speculate to prevent genetic introgression.(AU)

Corydoras compreende um gênero diversificado com espécies de diferentes números diploides. Nós comparamos dados citogenéticos de espécies de Corydoras de diferentes rios da região do Arco de Ponta Grossa no sul do Brasil. Corydoras ehrhardti e C. aff. paleatus tem fórmula cariotípica similar e o mesmo número diploide (2n = 44). Corydoras lacrimostigmata tem um número diploide maior, com 2n= 58 cromossomos. A hibridação in situ fluorescente (FISH) com sondas de DNA ribossomal 5S e 18S sugere que estas sequências de DNA ribossomal estão envolvidas em rearranjos cromossômicos nestas espécies de Corydoras. A marcação do DNAr 5S foi considerada espécie-específico para as espécies analisadas neste estudo. Sinais de sítios teloméricos intersticiais foram vistos em um par de cromossomos de C. lacrimostigmata sugerindo a ocorrência de rearranjos cromossômicos como fusões ou translocações. Este estudo revelou que as espécies C. ehrhardti e C. aff. paleatus têm marcadores cromossômicos exclusivos associados à diferenciação cromossômica, os quais, em nossa hipótese, podem prevenir a introgressão gênica.(AU)

Monosomal karyotype improves IPSS-R stratification in MDS and AML patients treated with Azacitidine.

IPSS-R classifies cytogenetic abnormalities into five prognostic groups for survival. Monosomal karyotype (MK) is not a subgroup of IPSS-R. Additional prognostic information from MK in poor and very poor karyotype has been recently shown. The aim of our study was to determine the prognostic value of IPSS-R and MK for response and survival in AZA-treated high-risk MDS and AML with 20-30% of blasts patients. The study population included 154 patients who were classified according to IPSS-R. IPSS-R was not predictive of response (intermediate, 64%; poor, 44%; very poor, 56%; P = 0.28) or survival (intermediate, 25 months; poor, 12 months; very poor, 11 months; P = 0.14). Twenty-one patients (15%) presented with MK and had a median OS of 9 months. Patients with a very high IPSS-R score without MK had a median OS of 15 months, while patients with a high IPSS-R score without MK had a median OS of 13 months (P = 0.18). We reclassified patients into the following three groups to include MK status: very high (MK only; OS median: 9 months), high (very high IPSS-R without MK and high IPSS-R without MK; OS median: 14 months) and intermediate (OS median: 25 months). As in recent publication including MK prognostic, we confirmed that this classification was predictive for survival in AZA treated patients (P = 0.008). IPSS-R failed to discriminate between the prognostic subgroups. Stratification with MK has value in the prognosis of our cohort of AZA-treated patients.