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Tiago Ribeiro, André Marques, Petr Novák, Veit Schubert, André L L Vanzela, Jiri Macas, Andreas Houben, Andrea Pedrosa-Harand
Satellite DNA repeats (or satDNA) are fast-evolving sequences usually associated with condensed heterochromatin. To test whether the chromosomal organisation of centromeric and non-centromeric satDNA differs in species with holocentric chromosomes, we identified and characterised the major satDNA families in the holocentric Cyperaceae species Rhynchospora ciliata (2n = 10), R. globosa (2n = 50) and R. tenuis (2n = 2x = 4 and 2n = 4x = 8). While conserved centromeric repeats (present in R. ciliata and R...
September 19, 2016: Chromosoma
Jimi L Rosenkrantz, Lucia Carbone
The steady occurrence of DNA mutations is a key source for evolution, generating the genomic variation in the population upon which natural selection acts. Mutations driving evolution have to occur in the oocytes and sperm in order to be transmitted to the next generation. Through similar mechanisms, mutations also accumulate in somatic cells (e.g., skin cells, neurons, lymphocytes) during development and adult life. The concept that somatic cells can collect new mutations with time suggests that we are a mosaic of cells with different genomic compositions...
September 16, 2016: Chromosoma
Benjamin M Skinner, Emma E P Johnson
Studies of chromosome and genome biology often focus on condensed chromatin in the form of chromosomes and neglect the non-dividing cells. Even when interphase nuclei are considered, they are often then treated as interchangeable round objects. However, different cell types can have very different nuclear shapes, and these shapes have impacts on cellular function; indeed, many pathologies are linked with alterations to nuclear shape. In this review, we describe some of the nuclear morphologies beyond the spherical and ovoid...
September 8, 2016: Chromosoma
Guilherme T Valente, Rafael T Nakajima, Bruno E A Fantinatti, Diego F Marques, Rodrigo O Almeida, Rafael P Simões, Cesar Martins
Though hundreds to thousands of reports have described the distribution of B chromosomes among diverse eukaryote groups, a comprehensive theory of their biological role has not yet clearly emerged. B chromosomes are classically understood as a sea of repetitive DNA sequences that are poor in genes and are maintained by a parasitic-drive mechanism during cell division. Recent developments in high-throughput DNA/RNA analyses have increased the resolution of B chromosome biology beyond those of classical and molecular cytogenetic methods; B chromosomes contain many transcriptionally active sequences, including genes, and can modulate the activity of autosomal genes...
August 24, 2016: Chromosoma
Katarzyna Piekarowicz, Magdalena Machowska, Ewelina Dratkiewicz, Daria Lorek, Agnieszka Madej-Pilarczyk, Ryszard Rzepecki
LMNA gene encodes for nuclear intermediate filament proteins lamin A/C. Mutations in this gene lead to a spectrum of genetic disorders, collectively referred to as laminopathies. Lamin A/C are widely expressed in most differentiated somatic cells but not in early embryos and some undifferentiated cells. To investigate the role of lamin A/C in cell phenotype maintenance and differentiation, which could be a determinant of the pathogenesis of laminopathies, we examined the role played by exogenous lamin A and its mutants in differentiated cell lines (HeLa, NHDF) and less-differentiated HEK 293 cells...
August 17, 2016: Chromosoma
Francisco J Ruiz-Ruano, Josefa Cabrero, María Dolores López-León, Juan Pedro M Camacho
B chromosomes are supernumerary genomic elements most likely derived from the standard (A) chromosomes, whose dispensability has freed their DNA sequences to evolve fast, thus making it difficult to uncover their ancestry. Here, we show the ancestry of a B chromosome in the grasshopper Eumigus monticola by means of the high-throughput analysis of the satellitome, i.e., the whole collection of satellite DNA (satDNA). The satellitome found in this species consists of 27 satDNA families, with monomer length between 5 and 325 nt and A + T content between 42...
August 13, 2016: Chromosoma
André Marques, Andrea Pedrosa-Harand
The centromere is the chromosomal site of kinetochore assembly and is responsible for the correct chromosome segregation during mitosis and meiosis in eukaryotes. Contrary to monocentrics, holocentric chromosomes lack a primary constriction, what is attributed to a kinetochore activity along almost the entire chromosome length during mitosis. This extended centromere structure imposes a problem during meiosis, since sister holocentromeres are not co-oriented during first meiotic division. Thus, regardless of the relatively conserved somatic chromosome structure of holocentrics, during meiosis holocentric chromosomes show different adaptations to deal with this condition...
September 2016: Chromosoma
Vladimir A Trifonov, Svetlana S Romanenko, Violetta R Beklemisheva, Larisa S Biltueva, Alexey I Makunin, Natalia A Lemskaya, Anastasia I Kulemzina, Roscoe Stanyon, Alexander S Graphodatsky
Acipenseriformes is an order of ray-finned fishes, comprising 27 extant species of sturgeons and paddlefishes inhabiting waters of the Northern Hemisphere. The order has a basal position within Actinopteri (ray-finned fish minus polypterids) and is characterized by many specific morphological and genomic features, including high diploid chromosome numbers, various levels of ploidy between species, unclear sex determination, and propensity to interspecific hybridization. Recent advances in molecular genetics, genomics, and comparative cytogenetics produced novel data on different aspects of acipenseriform biology, including improved phylogenetic reconstructions and better understanding of genome structure...
September 2016: Chromosoma
Harsh Nagpal, Tatsuo Fukagawa
The kinetochore is an essential structure for the chromosome segregation machinery in eukaryotes; it serves as a bridge between the spindle microtubules and chromosomes. The kinetochore consists of multiple interconnecting components on the centromere; therefore, understanding its formation, molecular function, and regulation has remained an ongoing challenge. Recent studies have provided new insights into centromere identity, kinetochore assembly, and function. In this review, we discuss recent advances in our understanding of the function and regulation of key kinetochore components...
September 2016: Chromosoma
Janine E Deakin, Maya Kruger-Andrzejewska
Chromosome rearrangements have been implicated in diseases, such as cancer, and speciation, but it remains unclear whether rearrangements are causal or merely a consequence of these processes. Two marsupial families with very different rates of karyotype evolution provide excellent models in which to study the role of chromosome rearrangements in a disease and evolutionary context. The speciose family Dasyuridae displays remarkable karyotypic conservation, with all species examined to date possessing nearly identical karyotypes...
September 2016: Chromosoma
Jorge V Beira, Renato Paro
The study of Drosophila imaginal discs has contributed to a number of discoveries in developmental and cellular biology. In addition to the elucidation of the role of tissue compartments and organ-specific master regulator genes during development, imaginal discs have also become well established as models for studying cellular interactions and complex genetic pathways. Here, we review key discoveries resulting from investigations of these epithelial precursor organs, ranging from cell fate determination and transdetermination to tissue patterning...
September 2016: Chromosoma
Natalay Kouprina, Vladimir Larionov
Transformation-associated recombination (TAR) cloning represents a unique tool for isolation and manipulation of large DNA molecules. The technique exploits a high level of homologous recombination in the yeast Sacharomyces cerevisiae. So far, TAR cloning is the only method available to selectively recover chromosomal segments up to 300 kb in length from complex and simple genomes. In addition, TAR cloning allows the assembly and cloning of entire microbe genomes up to several Mb as well as engineering of large metabolic pathways...
September 2016: Chromosoma
Chie Murata, Hirohito Sawaya, Katsushi Nakata, Fumio Yamada, Issei Imoto, Asato Kuroiwa
In initial studies of the eutherian small Indian mongoose (Herpestes auropunctatus), the Y chromosome could not be identified in somatic cells. The male chromosome number is uniquely odd, 2n = 35, whereas that of females is 2n = 36. Previous reports indicated that this unique karyotype resulted from a translocation of the ancestral Y chromosome to an autosome. However, it has been difficult to identify the chromosomes that harbor the translocated Y chromosomal segment because it is an extremely small euchromatic region...
September 2016: Chromosoma
Ines J de Castro, Ezgi Gokhan, Paola Vagnarelli
The maintenance of the correct cellular information goes beyond the simple transmission of an intact genetic code from one generation to the next. Epigenetic changes, topological cues and correct protein-protein interactions need to be re-established after each cell division to allow the next cell cycle to resume in the correct regulated manner. This process begins with mitotic exit and re-sets all the changes that occurred during mitosis thus restoring a functional G1 nucleus in preparation for the next cell cycle...
September 2016: Chromosoma
Hanneke Vlaming, Fred van Leeuwen
Histone modifications regulate key processes of eukaryotic genomes. Misregulation of the enzymes that place these modifications can lead to disease. An example of this is DOT1L, the enzyme that can mono-, di-, and trimethylate the nucleosome core on lysine 79 of histone H3 (H3K79). DOT1L plays a role in development and its misregulation has been implicated in several cancers, most notably leukemias caused by a rearrangement of the MLL gene. A DOT1L inhibitor is in clinical trials for these leukemias and shows promising results, yet we are only beginning to understand DOT1L's function and regulation in the cell...
September 2016: Chromosoma
Serge Romana, Isabelle Radford-Weiss, Jean-Michel Lapierre, Valérie Doye, Marie-Claude Geoffroy
Nup98 is an important component of the nuclear pore complex (NPC) and also a rare but recurrent target for chromosomal translocation in leukaemogenesis. Nup98 contains multiple cohesive Gly-Leu-Phe-Gly (GLFG) repeats that are critical notably for the formation of intranuclear GLFG bodies. Previous studies have reported the existence of GLFG bodies in cells overexpressing exogenous Nup98 or in a HeLa subline (HeLa-C) expressing an unusual elevated amount of endogenous Nup98. Here, we have analysed the presence of Nup98-containing bodies in several human cell lines...
September 2016: Chromosoma
Rocío Gómez, Kay Van Damme, Jaime Gosálvez, Eugenio Sánchez Morán, John K Colbourne
We present the first detailed cytological study of male meiosis in Daphnia (Crustacea: Branchiopoda: Cladocera)-an aquatic microcrustacean with a cyclical parthenogenetic life cycle. Using immunostaining of the testes in Daphnia magna for baseline knowledge, we characterized the different stages of meiotic division and spermiogenesis in relation to the distribution of proteins involved in synapsis, early recombination events and sister chromatid cohesion. We also studied post-translational histone modifications in male spermatocytes, in relation to the dynamic chromatin progression of meiosis...
September 2016: Chromosoma
Ulrich Knief, Wolfgang Forstmeier
Centromeres usually consist of hundreds of kilobases of repetitive sequence which renders them difficult to assemble. As a consequence, centromeres are often missing from assembled genomes and their locations on physical chromosome maps have to be inferred from flanking sequences via fluorescence in situ hybridization (FISH). Alternatively, centromere positions can be mapped using linkage analyses in accidentally triploid individuals formed by half-tetrads (resulting from the inheritance of two chromatids from a single meiosis)...
September 2016: Chromosoma
Oronzo Capozzi, Nicoletta Archidiacono, Nicola Lorusso, Roscoe Stanyon, Mariano Rocchi
Fluorescence in situ hybridization (FISH), especially chromosome painting, has been extensively exploited in the phylogenetic reconstruction of primate evolution. Although chromosome painting is a key method to map translocations, it is not effective in detecting chromosome inversions, which may be up to four times more frequent than other chromosomal rearrangements. BAC-FISH instead can economically delineate marker order and reveal intrachromosomal rearrangements. However, up to now, BAC-FISH was rarely used to study the chromosomes of New World monkeys partly due to technical difficulties...
September 2016: Chromosoma
Arpita Kulkarni, James W Lightfoot, Adrian Streit
Nematodes of the genus Strongyloides are important parasites of vertebrates including man. Currently, little is known about their germline organization or reproductive biology and how this influences their parasitic life strategies. Here, we analyze the structure of the germline in several Strongyloides and closely related species and uncover striking differences in the development, germline organization, and fluid dynamics compared to the model organism Caenorhabditis elegans. With a focus on Strongyloides ratti, we reveal that the proliferation of germ cells is restricted to early and mid-larval development, thus limiting the number of progeny...
September 2016: Chromosoma
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