Karyotypic Changes Research Articles

Karyotype stability in the genusPhaseolusevidenced by the comparative mapping of the wild speciesPhaseolus microcarpus

The genus Phaseolus L. (Fabaceae) is monophyletic and comprises approximately 75 species distributed into two principal clades. The five cultivated species, including the common bean (Phaseolus vulgaris), were placed in clade B. Clade A comprises only wild species, with more limited distribution. In the present work, bacterial artificial chromosomes (BACs) previously mapped in common bean (2n = 22) were used as probes in fluorescent in situ hybridization (FISH) in this comparative study of Phaseolus microcarpus (2n = 22), a species from clade A. We also analyzed the chromomycin A3 (CMA)/4',6-diamidino-2-phenylindole (DAPI) banding pattern and the localization of rDNA and telomeric DNA sites. The single 45S rDNA site from P. microcarpus was mapped to chromosome 6, showing conservation to the P. vulgaris homeolog. Of the two 5S rDNA sites identified in both species, only the site on chromosome 10 appeared conserved. In spite of the phylogenetic distance between the two species, all of the single-copy BACs demonstrated conservation of synteny. However, four collinearity breaks were observed, probably caused by para- and pericentric inversions. Some variation in the repetitive fraction of the genome was also observed. Thus, a broader analysis of the genus confirms that few, rare inversions seem to represent the main karyotype changes during the evolution of this genus.

Chromosome evolution in Neotropical butterflies

We list the chromosome numbers for 65 species of Neotropical Hesperiidae and 104 species or subspecies of Pieridae. In Hesperiidae the tribe Pyrrhopygini have a modal n = 28, Eudaminae and Pyrgini a modal n = 31, while Hesperiinae have n = around 29. Among Pieridae, Coliadinae have a strong modal n = 31 and among Pierinae Anthocharidini are almost fixed for n = 15 while Pierini vary with n = 26 as the most common chromosome number. Dismorphiinae show wide variation. We discuss these results in the context of chromosome numbers of over 1400 Neotropical butterfly species and subspecies derived from about 3000 populations published here and in earlier papers of a series. The overall results show that many Neotropical groups are characterized by karyotype instability with several derived modal numbers or none at all, while almost all taxa of Lepidoptera studied from the other parts of the world have one of n = 29-31 as modal numbers. Possibly chromosome number changes become fixed in the course of speciation driven by biotic interactions. Population subdivision and structuring facilitate karyotype change. Factors that stabilize chromosome numbers include hybridization among species sharing the same number, migration, sexual selection and possibly the distribution of chromosomes within the nucleus.

Aneuploidy and chromosomal instability: a vicious cycle driving cellular evolution and cancer genome chaos

Aneuploidy and chromosomal instability frequently co-exist, and aneuploidy is recognized as a direct outcome of chromosomal instability. However, chromosomal instability is widely viewed as a consequence of mutations in genes involved in DNA replication, chromosome segregation, and cell cycle checkpoints. Telomere attrition and presence of extra centrosomes have also been recognized as causative for errors in genomic transmission. Here, we examine recent studies suggesting that aneuploidy itself can be responsible for the procreation of chromosomal instability. Evidence from both yeast and mammalian experimental models suggests that changes in chromosome copy number can cause changes in dosage of the products of many genes located on aneuploid chromosomes. These effects on gene expression can alter the balanced stoichiometry of various protein complexes, causing perturbations of their functions. Therefore, phenotypic consequences of aneuploidy will include chromosomal instability if the balanced stoichiometry of protein machineries responsible for accurate chromosome segregation is affected enough to perturb the function. The degree of chromosomal instability will depend on specific karyotypic changes, which may be due to dosage imbalances of specific genes or lack of scaling between chromosome segregation load and the capacity of the mitotic system. We propose that the relationship between aneuploidy and chromosomal instability can be envisioned as a "vicious cycle," where aneuploidy potentiates chromosomal instability leading to further karyotype diversity in the affected population.

Chromosomal instability and transcriptome dynamics in cancer

Whole transcriptome profiling has long been proposed as a method of identifying cancer-specific gene expression profiles. Indeed, a multitude of these studies have generated vast amounts of expression data for many types of cancer, and most have identified specific gene signatures associated with a given cancer. These studies however, often contradict with each other, and gene lists only rarely overlap, challenging clinical application of cancer gene signatures. To understand this issue, the biological basis of transcriptome dynamics needs to be addressed. Chromosome instability (CIN) is the main contributor to genome heterogeneity and system dynamics, therefore the relationship between CIN, genome heterogeneity, and transcriptome dynamics has important implications for cancer research. In this review, we discuss CIN and its effects on the transcriptome during cancer progression, specifically how stochastic chromosome change results in transcriptome dynamics. This discussion is further applied to metastasis and drug resistance both of which have been linked to multiple diverse molecular mechanisms but are in fact driven by CIN. The diverse molecular mechanisms that drive each process are linked to karyotypic heterogeneity through the evolutionary mechanism of cancer. Karyotypic change and the resultant transcriptome change alter network function within cells increasing the evolutionary potential of the tumor. Future studies must embrace this instability-induced heterogeneity in order to devise new research and treatment modalities that focus on the evolutionary process of cancer rather than the individual genes that are uniquely changed in each tumor. Care is also needed in evaluating results from experimental systems which measure average values of a population.

Diverse chromosome complements in the functional gametes of interspecific hybrids of MT- and A-karyotype Lycoris spp.

The karyotype and numeric changes in chromosomes among taxa of Lycoris (spider lilies) have been attributed to whole-arm rearrangements; however, the history of karyotype evolution of Lycoris is still ambiguous. In the natural habitat, one-third of Lycoris taxa are interspecific hybrids that are mainly sterile and extremely diverse in morphologies. Lycoris are geophytes with the reproductive stage initiated inside the bulbs during the storage period, which brings some inconveniences in collecting meiotic materials for studying chromosome pairing. The partial fertility of an artificial F1 interspecific hybrid between L. aurea (2n = 14) and L. radiata (2n = 22) provides an alternative option for tracing the meiotic process in F1 hybrids. The chromosome compositions of those functional gametes generated by the F1 hybrid could be recovered according to the chromosome complements of backcross progenies. We perform genomic in situ hybridization (GISH) analysis on somatic chromosomes of 34 BC1 plants (2n = 14–22) to reveal chromosomal divergences in number and composition of those functional gametes. GISH results also indicated a high homology between the MT- and A-genomes of Lycoris, reflecting on the partial fertility and frequently homoeologous recombination at meiosis of the F1 interspecific hybrids. The diverse chromosome complements and recombinant patterns presented in these functional gametes suggested that interspecific hybridization is an important force in driving diversification among Lycoris species. We suggest that the MT-karyotype genome may be the ancestral type in Lycoris, and some other chromosomal rearrangements in addition to centromeric fission may have played roles in the karyotype evolution of Lycoris.

SNP-based analysis of genetic diversity in anther-derived rice by whole genome sequencing

BackgroundAnther culture has advantage to obtain a homozygous progeny by induced doubling of haploid chromosomes and to improve selection efficiency for invaluable agronomical traits. Therefore, anther culturing is widely utilized to breed new varieties and to induce genetic variations in several crops including rice. Genome sequencing technologies allow the detection of a massive number of DNA polymorphism such as SNPs and Indels between closely related cultivars. These DNA polymorphisms permit the rapid identification of genetic diversity among cultivars and genomic locations of heritable traits. To estimate sequence diversity derived from anther culturing, we performed whole-genome resequencing of five Korean rice accessions, including three anther culture lines (BLB, HY-04 and HY-08), their progenitor cultivar (Hwayeong), and an additional japonica cultivar (Dongjin).ResultsA total of 1,165 × 106 raw reads were generated with over 58× coverage that detected 1,154,063 DNA polymorphisms between the Korean rice accessions and Nipponbare. We observed that in Hwayeong and its progenies, 0.64 SNP was found per one kb of Nipponbare genome, while Dongjin, bred by a conventional breeding method, had a lower number of SNPs (0.45 SNP/kb). Among 1,154,063 DNA polymorphisms, 29,269 non-synonymous SNPs located on 30,013 genes and these genes were functionally classified based on gene ontology (GO). We also analyzed line-specific SNPs which were estimated 1 ~ 3% of the total SNPs. The frequency of non-synonymous SNPs in each accession ranged from 26 SNPs in Hwayeong to 214 SNPs in HY-04.ConclusionsThe genetic difference we detected between the progenies derived from anther culture and their mother cultivar is due to somaclonal variation during tissue culture process, such as karyotype change, chromosome rearrangement, gene amplification and deletion, transposable element, and DNA methylation. Detection of genome-wide DNA polymorphisms by high-throughput sequencer enabled to identify sequence diversity derived from anther culturing and genomic locations of heritable traits. Furthermore, it will provide an invaluable resource to identify molecular markers and genes associated with diverse traits of agronomical importance.Electronic supplementary materialThe online version of this article (doi:10.1186/1939-8433-6-6) contains supplementary material, which is available to authorized users.

Exploring the biology of cancer of unknown primary: breakthroughs and drawbacks

Cancer of unknown primary (CUP) ranks among the ten most common malignancies worldwide. Cancer of unknown primary presents as disseminated disease, has a dismal prognosis and remains a diagnosis of exclusion. The natural history and biology of the disease is poorly understood, and efforts are focused on identifying the specific 'CUP signature'. We collected and analysed all published research in the biology of CUP from 1974 till present (Medline, Embase, ASCO and ESMO Congresses). Current scientific evidence suggests that aneuploidy and karyotype changes are frequent, while more subtle molecular aberrations, such as epidermal growth factor receptor family proteins, cKit/PDGFR are frequently overexpressed, although without prognostic significance. Loss of function of tumour suppressor genes, active angiogenesis, a hypoxic genetic programme and a mesenchymal transitory phenotype have been reported in CUP and may be indicative of unfavourable prognosis. Molecular pathway analyses have identified various biomolecules impacting on survival (pAKT, pMAPK, c-Met, p21 and pPRS6). Finally, circulating tumour cells have recently been reported as a frequent phenomenon in CUP. Overall, advances in understanding CUP biology have been weak and the application of gene expression profiling failed to identify an as yet elusive 'CUP molecular signature'. MicroRNA, epigenetic and proteomic studies are warranted to better characterize the biological profile of CUP and unravel its mystery.

Karyotypic change between diagnosis and relapse as a predictor of salvage therapy outcome in AML patients

BackgroundOnly a few patients who experience AML relapse derive lasting benefit from re-induction therapy. The utility of reassessing the disease karyotype at relapse is unclear. The main goals of this study were to identify prognostic factors for AML relapse and to determine the prognostic utility of karyotypic change between diagnosis and relapse as a variable for predicting response to salvage therapy for relapsed AML.MethodsThis retrospective study included 58 patients with relapsed AML treated at the Yonsei University College of Medicine between 2005 and 2010. Karyotypes at both diagnosis and relapse were available for 45 patients (77%). A change in karyotype at relapse was observed in 17 of 45 cases (37%), and no change was noted in 28 of 45 cases (62%).ResultsKaryotypic changes between diagnosis and relapse were associated with the response rate (RR) to salvage therapy (P=0.016). Overall survival (OS) and event-free survival (EFS) in the group with karyotypic changes between diagnosis and relapse were significantly different from those with no karyotypic changes (P=0.004 and P=0.010, respectively). We applied multiple multivariate Cox regression analyses to identify independent prognostic factors for overall response (OR), OS, and EFS. A change in karyotype between diagnosis and relapse was significantly associated with OS (P=0.023; RR=2.655) and EFS (P=0.033; RR=2.831).ConclusionKaryotypic changes between the diagnosis and relapse of AML could be used to predict outcomes and tailor clinical and biological therapeutic strategies for relapsed AML patients.

A de novo acute myeloid leukemia (AML-M4) case with a complex karyotype and yet unreported breakpoints

BackgroundAcute myelogeneous leukemia (AML) is a malignancy of the hematopoietic stem cells, for which cytogenetic analysis is still one of the most important diagnostic and prognostic tools. Still, we are far away from having seen and described all possible genetic changes associated with this kind of acquired disease.ResultsBone marrow cells of a female patient with clinical diagnoses of AML and immunophenotypically confirmed AML-M4 were studied by GTG-banding. The later was not able to resolve all karyotypic changes and the complex karyotype was characterized in more detail by fluorescence in situ hybridization (FISH) and array-proven multicolor banding (aMCB). To the best of our knowledge, the present case is the only one ever seen with a del(5)(q14q34), a der(17)t(4;17)(p13;p13), a del(2)(p23), a der(4)t(4;7)(p13;q11.23), a der(22)t(11;22)(q23;q11.2) and two complex rearranged chromosomes 11 involving chromosomes 7 and 22 as well as 2.ConclusionsThe yet unreported breakpoints observed in this case seem to be correlated with an adverse prognosis. Overall, molecular cytogenetic studies are suited best for identification and characterization of chromosomal rearrangements in acute leukemia and single case reports as well as large scale studies are necessary to provide further insides in karyotypic changes taking place in human malignancies.

Prognostic Implications of Cytogenetic Features in Myelodysplastic Syndromes

Myelodysplastic Syndromes (MDS) are a heterogeneous group of hematologic diseases characterized by refractory cytopenia(s) and variable risk of leukemic progression. Cytogenetic analysis is important in day-to-day clinical practice helping to define subgroups of MDS patients who share similarities in the course of the disease. There are recurring aberrations affecting chromosomes 5, 7, 8, and 20. While all of them do not suggest a therapeutic approach, their presence has been considered as a risk indicator since the original international prognostic scoring system (IPSS) was published. The most recent cytogenetic stratifications tried to find the prognostic significance of less frequent alterations which have been longer included in the intermediate group. Moreover, monitoring of karyotype changes is suggested to evaluate cytogenetic response to treatments and the acquisition of new aberrations associated to an unfavorable outcome. This review focuses on different cytogenetic risk stratifications that have been published during the past 20 years and the molecular background of the most relevant chromosomal findings.

Differential occurrence of chromosome inversion polymorphisms among Muller's elements in three species of thetripunctatagroup ofDrosophila, including a species with fast chromosomal evolution

Detailed chromosome maps with reliable homologies among chromosomes of different species are the first step to study the evolution of the genetic architecture in any set of species. Here, we present detailed photo maps of the polytene chromosomes of three closely related species of the tripunctata group (subgenus Drosophila): Drosophila mediopunctata, D. roehrae, and D. unipunctata. We identified Muller's elements in each species, using FISH, establishing reliable chromosome homologies among species and D. melanogaster. The simultaneous analysis of chromosome inversions revealed a distribution pattern for the inversion polymorphisms among Muller's elements in the three species. Element E is the most polymorphic, with many inversions in each species. Element C follows; while the least polymorphic elements are B and D. While interesting, it remains to be determined how general this pattern is among species of the tripunctata group. Despite previous studies showing that D. mediopunctata and D. unipunctata are phylogenetically closer to each other than to D. roehrae, D. unipunctata shows rare karyotypic changes. It has two chromosome fusions: an additional heterochromatic chromosome pair and a pericentric inversion in the X chromosome. This especial conformation suggests a fast chromosomal evolution that deserves further study.

Karyotypic and Molecular Genetic Changes Associated With Fetal Cardiovascular Abnormalities: Results of a Retrospective 4-Year Ultrasonic Diagnosis Study

Objective: To investigate the incidence of aneuploidy in fetuses with congenital heart defects (CHDs) and to further identify submicroscopic changes and global DNA methylation levels as potential biomarkers in complex CHD cases.Methods: Fetuses at high risk for birth defects or with obvious sonographic anomalies were recruited at the Prenatal Diagnosis Center and Ultrasonic Diagnosis Center. Elective fetal karyotyping and DNA copy number and promoter methylation analyses were carried out following parental consent. G-banded karyotyping was performed to detect fetal aneuploidy. Copy number variations (CNVs) were detected using the Affymetrix SNP Array 6.0 and validated by real time PCR. Global DNA methylation analyses were conducted using a Roche NimbleGen Human DNA Methylation 3x720K Array, and DNA methylation differences were assayed by a Sequenom MassARRAY EpiTYPER.Results: Conventional karyotyping identified 30 cases with aneuploidy in 179 CHD fetuses. Various CNVs were found in two aneuploid fetuses and in five euploid CHD fetuses. Verified segmental deletion or duplications were not directly associated with cardiovascular malformations except in DAAM1 and GATA6. Verifiable aberrant DNA methylation could not be identified in three complex CHD fetuses.Conclusions: In this study, Trisomy 18, Trisomy 21 and 45,XO were the most common aneuploidies identified in CHD fetuses. In the affected samples, only DAAM1 deletion and GATA6 amplification could be associated with cardiovascular biological processes.

DETERMINING WATER GENOTOXICITY AT SOME SITES ON HUNTING GROUNDS IN VOJVODINA

Various biotic and abiotic factors are present in ecosystem and they influence the processes of living organisms. Some agents that come into natural waterways are genotoxic. They affect genome and during mitosis and meiosis, and cause numerical and structural changes in karyotype. A research on the degree of genotoxicity on water was carried out on some hunting grounds in Vojvodina. Three sites were selected in Srem, Banat and Backa and water was sampled at different levels of the above mentioned habitats. A cumulative sample was made for each site. Cytological and cytogenetic changes in mitosis were analyzed on the lymphocyte mammalian samples applying Allium cepa genotoxic test. The obtained results point out that the toxicity of water is of different degree and depends on the level of environmental pollution. The hunting ground in Srem is located in the forest where water resources are not polluted, what affected the results showing favorable cytogenetic findings. Genotoxicity of water was detected in Backa where the channel, available to the game, is surrounded by contaminated ground. The changes in cell division were detected, as well as numerical and structural changes in the genome. Banat hunting ground is located in the fields. No contamination was observed. Changes in cytological level that were detected by cytogenetic analysis were statistically not significant. Further and expanded research is needed, as the applied scope of this work proved to be insufficient. However, it indicates the presence of water genotoxicity on hunting grounds in Vojvodina.

Gross karyotypic and phenotypic alterations among different progenies of the Candida glabrata CBS138/ATCC2001 reference strain.

Genomic plasticity is a mechanism for adaptation to environmental cues such as host responses and antifungal drug pressure in many fungi including the human pathogenic yeast Candida glabrata. In this study we evaluated the phenotypic and genotypic stability of the world-wide used C. glabrata reference strain CBS138/ATCC2001 under laboratory conditions. A set of ten lineages of this wild type strain and genetically modified progenies were obtained from different scientific laboratories, and analyzed for genotypic and phenotypic alterations. Even though the derivates were indistinguishable by multi locus sequence typing, different phenotypic groups that correlated with specific karyotypic changes were observed. In addition, modifications in the adherence capacity to plastic surface emerged that were shown to correlate with quantitative changes in adhesin gene expression rather than subtelomeric gene loss or differences in the number of macrosatellite repeats within adhesin genes. These results confirm the genomic plasticity of C. glabrata and show that chromosomal aberrations and functional adaptations may occur not only during infection and under antimicrobial therapy, but also under laboratory conditions without extreme selective pressures. These alterations can significantly affect phenotypic properties such as cell surface attributes including adhesion and the cell wall carbohydrate composition and therefore, if unnoticed, may adulterate the outcome of genetic studies.

Karyotypic diversity and evolutionary trends in the Neotropical catfish genus Hypostomus Lacépède, 1803 (Teleostei, Siluriformes, Loricariidae)

The family Loricariidae with 813 nominal species is one of the largest fish families of the world. Hypostominae, its more complex subfamily, was recently divided into five tribes. The tribe Hypostomini is composed of a single genus, Hypostomus Lacépède, 1803, which exhibits the largest karyotypic diversity in the family Loricariidae. With the main objective of contributing to a better understanding of the relationship and the patterns of evolution among the karyotypes of Hypostomus species, cytogenetic studies were conducted in six species of the genus from Brazil and Venezuela. The results show a great chromosome variety with diploid numbers ranging from 2n=68 to 2n=76, with a clear predominance of acrocentric chromosomes. The Ag-NORs are located in terminal position in all species analyzed. Three species have single Ag-NORs (Hypostomus albopunctatus (Regan, 1908), Hypostomus prope plecostomus (Linnaeus, 1758), and Hypostomus prope paulinus (Ihering, 1905)) and three have multiple Ag-NORs (Hypostomus ancistroides (Ihering, 1911), Hypostomus prope iheringi (Regan, 1908), and Hypostomus strigaticeps (Regan, 1908)). In the process of karyotype evolution of the group, the main type of chromosome rearrangements was possibly centric fissions, which may have been facilitated by the putative tetraploid origin of Hypostomus species. The relationship between the karyotype changes and the evolution in the genus is discussed.

Chromosome and genome size variation inLuzula(Juncaceae), a genus with holocentric chromosomes

The present study examines chromosome and genome size evolution in Luzula (woodrush; Juncaceae), a monocot genus with holocentric chromosomes. Detailed karyotypes and genome size estimates were obtained for seven Luzula spp., and these were combined with additional data from the literature to enable a comprehensive cytological analysis of the genus. So that the direction of karyotype and genome size changes could be determined, the cytological data were superimposed onto a phylogenetic tree based on the trnL-F and internal transcribed spacer (ITS) DNA regions. Overall, Luzula shows considerable cytological variation both in terms of chromosome number (2n = 6–66) and genome size (15-fold variation; 2C = 0.56–8.51 pg; 547.7–8322.8 Mb). In addition, there is considerable diversity in the genomic mechanisms responsible, with the range of karyotypes arising via agmatoploidy (chromosome fission), symploidy (chromosome fusion) and/or polyploidy accompanied, in some cases, by the amplification or elimination of DNA. Viewed in an evolutionary framework, no broad trend in karyotype or genome evolution was apparent across the genus; instead, different mechanisms of karyotype evolution appear to be operating in different clades. It is clear that Luzula exhibits considerable genomic flexibility and tolerance to large, genome-scale changes.

Translocation t(1;6)(p35.3;p25.2) Involves RCC1 and IRF4 and Is Not Restricted to Unmutated Chronic Lymphocytic Leukemia

AbstractAbstract 4584 IntroductionThe disease course of B-cel chronic lymphocytic leukemia (CLL) is highly variable and genetic aberrations help to stratify patients with different prognosis. Therefore, detailed characterization of CLL associated chromosomal aberrations is important in order to identify patient subsets who need close monitoring and early therapy. The t(1;6)(p35.3;p25.2) involving IRF4 is extremely rare in CLL and has been associated with high-risk chromosomal aberrations [i.e. del(11q) and del(17p)], unmutated IGHV status and a rather progressive clinical course. AimHere, we report the clinical, morphological and cytogenetic features of five new patients with a t(1;6)(p35.3;p25.2) and characterize for the first time the breakpoints at the molecular level. Materials and methodsFive patients with B-NHL and a t(1;6)(p36∼p33;p25∼p23) in the karyotype were included in the study. Immunophenotype and/or morphology corresponded with CLL in 4/5 cases. The fifth case presented with follicular lymphoma (FL). The t(1;6)(p35.3;p25.2) was confirmed by FISH in all cases. ResultsWhen the 5 additional cases are considered together with 8 previously reported (Michaux et al., 2005), the female/male ratio is 3/10 with a median age of 63 (range 33–81). Four of the CLL patients presented with Binet stage A, 5 with stage B and 3 with stage C. Median leukocytosis was 11.8×109/L (range 1.8–103×109/L), LDH levels were elevated in 2 and CD38 was expressed in 7/9 patients. Nine patients showed an unmutated and 2 a mutated IGHV status (not available: n=2). Eleven patients required therapy, 0.5–62 months (median 0.5 month) after diagnosis. Only one of the 5 new cases was refractory to the therapy and died due to the disease after a follow-up of 20 months.The t(1;6) was found as the sole karyotypic change in 2 cases and was associated with one abnormality in 2 other cases (i.e. a +12 and a +15). The case with FL showed a complex composite karyotype. In addition, FISH detected a cryptic del(11q) and del(17p) in one case each. The 1p breakpoint was mapped to a 500Kb region between BACs RP11–290H1 and RP11–442N24 and the 6p breakpoint into the BAC RP11–233K4.Molecular analysis of 7 t(1;6) positive patients confirmed the presence of the translocation and demonstrated a fusion between the 5' end of RCC1 (in intron 1, 2 or 3) on 1p35, and IRF4 (in intron 1) on 6p25. The resulting fusion transcript consists of RCC1 exon 1, exon 2 or exon 3, linked to exon 2 of IRF4. In one patient, a 48 basepair long insert from intron 3 was present between RCC1 exon 3 and IRF4 exon 2. The first 4 exons of RCC1 are part of the 5'- untranslated region, whereas the open reading frame of IRF4 starts at exon 2. As such, the t(1;6) likely alters the expression of IRF4. Discussion and conclusionThe RCC1 protein is widely expressed and is involved in chromatin condensation. IRF4 is a transcription factor with expression restricted to the immune system. The IRF4 protein plays a critical role in B-cell differentiation and mature T- and B-lymphocyte function. The t(6;14)(p25.2;q32) which juxtaposes IRF4 to the immunoglobulin loci (IG) resulting in IRF4 overexpression, has been reported in rare multiple myeloma (MM) cases and other mature B-NHLs. The oncogenic capacity of IRF4 has been demonstrated in MM. In CLL, the role of IRF4 remains unknown. Heterogeneous IRF4 expression has been observed between patients and examined tissues, and data on prognostic significance are conflicting. Here, we report 5 additional cases with t(1;6)(p35.3;p25.2) and demonstrate that this translocation is seen in unmutated CLL, as well as in mutated CLL and other indolent lymphoproliferative disorders. This is in contrast to the previously reported exclusive association of t(1;6) with unmutated CLL. At the molecular level, the t(1;6) results in a fusion transcript between RCC1 and IRF4 by which IRF4 expression is altered. Recognition of this and other translocations is important in order to refine the prognostic stratification of patients with CLL. Disclosures:No relevant conflicts of interest to declare.

Heading off with the herd: how cancer cells might maneuver supernumerary centrosomes for directional migration

The complicity of centrosomes in carcinogenesis is unmistakable. Mounting evidence clearly implicates a robust correlation between centrosome amplification (CA) and malignant transformation in diverse tissue types. Furthermore, CA has been suggested as a marker of cancer aggressiveness, in particular the invasive phenotype, in breast and prostate cancers. One means by which CA promotes malignancy is through induction of transient spindle multipolarity during mitosis, which predisposes the cell to karyotypic changes arising from low-grade chromosome mis-segregation. It is well recognized that during cell migration in interphase, centrosome-mediated nucleation of a radial microtubule array is crucial for establishing a polarized Golgi apparatus, without which directionality is precluded. The question of how cancer cells maneuver their supernumerary centrosomes to achieve directionality during cell migration is virtually uncharted territory. Given that CA is a hallmark of cancers and has been correlated with cancer aggressiveness, malignant cells are presumably competent in managing their centrosome surfeit during directional migration, although the cellular logistics of this process remain unexplored. Another key angle worth pondering is whether an overabundance of centrosomes confers some advantage on cancer cells in terms of their migratory and invasive capabilities. Recent studies have uncovered a remarkable strategy that cancer cells employ to deal with the problem of excess centrosomes and ensure bipolar mitoses, viz., centrosome clustering. This review aims to change the narrative by exploring how an increased centrosome complement may, via aneuploidy-independent modulation of the microtubule cytoskeleton, enhance directional migration and invasion of malignant cells. We postulate that CA imbues cancer cells with cytoskeletal advantages that enhance cell polarization, Golgi-dependent vesicular trafficking, stromal invasion, and other aspects of metastatic progression. We also propose that centrosome declustering may represent a novel, cancer cell-specific antimetastatic strategy, as cancer cells may rely on centrosome clustering during migration as they do in mitosis. Elucidation of these details offers an exciting avenue for future research, as does investigating how CA may promote metastasis through enhanced directional migration.

Phylogeny of Crocus (Iridaceae) based on one chloroplast and two nuclear loci: Ancient hybridization and chromosome number evolution

Crocus consists of about 100 species distributed from western Europe and northern Africa to western China, with the center of diversity on the Balkan Peninsula and in Asia Minor. Our study focuses on clarifying phylogenetic relationships and chromosome number evolution within the genus using sequences of the chloroplast trnL-F region, the nuclear ribosomal DNA internal transcribed spacer (ITS) region, and a part of the nuclear single-copy gene pCOSAt103.In a combined dataset of ITS and trnL-F sequences, 115 individuals representing 110 taxa from both subgenera and all sections and series of Crocus were analyzed with Bayesian phylogenetic inference. For pCOSAt103 79 individuals representing 74 Crocus taxa were included, and for the majority of them PCR amplicons were cloned and up to eight clones per individual were sequenced to detect allopolyploidization events. Romulea species were included as outgroup in both analyses. Characteristics of seed surface structures were evaluated by scanning electron microscopy.Phylogenetic analysis of ITS/trnL-F data resulted in a monophyletic genus Crocus, probably monophyletic sections Crocus and Nudiscapus, and inferred monophyly for eight of the 15 series of the genus. The C. biflorus aggregate, thought to be consisting of closely related subspecies, was found to be polyphyletic, the taxa occurring within three major clades in the phylogenetic tree. Cloning of pCOSAt103 resulted in the detection of homoeologous copies in about one third of the taxa of section Nudiscapus, indicating an allotetraploid origin of this section. Reconstruction of chromosome number evolution along the phylogenetic tree using a probabilistic and a parsimony approach arrived at partly contradictory results. Both analyses agreed however on the occurrence of multiple polyploidization and dysploidy events. B chromosomes evolved at least five times independently within the genus, preferentially in clades characterized by karyotype changes.

Prognostic features of patients with myelodysplastic syndromes aged < 50 years: update of a single-institution experience

Fewer than 10% of patients with myelodysplastic syndromes (MDS) are younger than 50 years. A series of 91 younger patients (median age 44 years with female prevalence) are reported and compared with elderly patients. Frequent karyotypic changes were trisomy 8 (9.8%) and monosomy 7 (5%). Twenty-three patients had occupational exposure to potential mutagens (benzene and solvents), with a male predominance, higher frequency of refractory cytopenia with multilineage dysplasia (RCMD) (52%) and higher frequency of monosomy 7 (21.7%). At a median follow-up of 72 months, 22 patients (24%) evolved to acute leukemia, with higher frequency being observed among the exposed cohort (39% vs. 19% non-exposed). Unfavorable factors for overall survival were: age > 40 years, > 5% of blasts, trilinear bone marrow involvement and intermediate–high World Health Organization Prognostic Scoring System (WPSS) risk. The present results suggest that younger MDS could be identified as a distinct subset. For patients belonging to the low/intermediate-I risk group, due to a low transformation rate, aggressive approaches should rarely be recommended.