Small supernumerary marker chromosomes (sSMC) in humans; are there B chromosomes hidden among them

<p>Abstract</p> <p>Background</p> <p>Small supernumerary marker chromosomes (sSMC) and B-chromosomes represent a heterogeneous collection of chromosomes added to the typical karyotype, and which are both small in size. They may consist of heterochromatic and/or euchromatic material. Also a predominance of maternal transmission was reported for both groups. Even though sSMC and B-chromosomes show some similarity it is still an open question if B-chromosomes are present among the heterogeneous group of sSMC. According to current theories, sSMC would need drive, drift or beneficial effects to increase in frequency in order to become B chromosome. However, up to now no B-chromosomes were described in human.</p> <p>Results</p> <p>Here we provide first evidence and discuss, that among sSMC B-chromosomes might be hidden. We present two potential candidates which may already be, or may in future evolve into B chromosomes in human: (i) sSMC cases where the marker is stainable only by DNA derived from itself; and (ii) acrocentric-derived inverted duplication sSMC without associated clinical phenotype. Here we report on the second sSMC stainable exclusively by its own DNA and show that for acrocentric derived sSMC 3.9× more are familial cases than reported for other sSMC.</p> <p>Conclusion</p> <p>The majority of sSMC are not to be considered as B-chromosomes. Nonetheless, a minority of sSMC show similarities to B-chromosomes. Further studies are necessary to come to final conclusions for that problem.</p

Aplicación de la mejora continua al área de seguridad industrial y salud ocupacional para reducir los costos por accidentes laborales en la empresa Camposol S.A.

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Key factors of combustion: from kinetics to gas dynamics

This book summarizes the main advances in the mechanisms of combustion processes. It focuses on the analysis of kinetic mechanisms of gas combustion processes and experimental investigation into the interrelation of kinetics and gas dynamics in gas combustion. The book is complimentary to the one previously published, The Modes of Gaseous Combustion

Coherent control of symmetry breaking in transverse-field Ising chains using few-cycle pulses

Coherent control of quantum systems with phase-stable pulses offers enticing new opportunities for lightwave electronics. Here we extend this approach to many-body systems with spin degrees of freedom, demonstrating that a single few-cycle control pulse can create a sizable population asymmetry between the two degenerate polar ground states of the Ising model. This opens a route for femtosecond-scale data processing and storage, allowing one to control the final ground state of a correlated system in an all-optical way

New Insights into Phasmatodea Chromosomes

Currently, approximately 3000 species of stick insects are known; however, chromosome numbers, which range between 21 and 88, are known for only a few of these insects. Also, centromere banding staining (C-banding) patterns were described for fewer than 10 species, and fluorescence in situ hybridization (FISH) was applied exclusively in two Leptynia species. Interestingly, 10–25% of stick insects (Phasmatodea) are obligatory or facultative parthenogenetic. As clonal and/or bisexual reproduction can affect chromosomal evolution, stick insect karyotypes need to be studied more intensely. Chromosome preparation from embryos of five Phasmatodea species (Medauroidea extradentata, Sungaya inexpectata, Sipyloidea sipylus, Phaenopharos khaoyaiensis, and Peruphasma schultei) from four families were studied here by C-banding and FISH applying ribosomal deoxyribonucleic acid (rDNA) and telomeric repeat probes. For three species, data on chromosome numbers and structure were obtained here for the first time, i.e., S. inexpectata, P. khaoyaiensis, and P. schultei. Large C-positive regions enriched with rDNA were identified in all five studied, distantly related species. Some of these C-positive blocks were enriched for telomeric repeats, as well. Chromosomal evolution of stick insects is characterized by variations in chromosome numbers as well as transposition and amplification of repetitive DNA sequences. Here, the first steps were made towards identification of individual chromosomes in Phasmatodea

New Insights into Phasmatodea Chromosomes

Currently, approximately 3000 species of stick insects are known; however, chromosome numbers, which range between 21 and 88, are known for only a few of these insects. Also, centromere banding staining (C-banding) patterns were described for fewer than 10 species, and fluorescence in situ hybridization (FISH) was applied exclusively in two Leptynia species. Interestingly, 10–25% of stick insects (Phasmatodea) are obligatory or facultative parthenogenetic. As clonal and/or bisexual reproduction can affect chromosomal evolution, stick insect karyotypes need to be studied more intensely. Chromosome preparation from embryos of five Phasmatodea species (Medauroidea extradentata, Sungaya inexpectata, Sipyloidea sipylus, Phaenopharos khaoyaiensis, and Peruphasma schultei) from four families were studied here by C-banding and FISH applying ribosomal deoxyribonucleic acid (rDNA) and telomeric repeat probes. For three species, data on chromosome numbers and structure were obtained here for the first time, i.e., S. inexpectata, P. khaoyaiensis, and P. schultei. Large C-positive regions enriched with rDNA were identified in all five studied, distantly related species. Some of these C-positive blocks were enriched for telomeric repeats, as well. Chromosomal evolution of stick insects is characterized by variations in chromosome numbers as well as transposition and amplification of repetitive DNA sequences. Here, the first steps were made towards identification of individual chromosomes in Phasmatodea

Visualizing the Genome: Experimental Approaches for Live-Cell Chromatin Imaging

Over the years, our vision of the genome has changed from a linear molecule to that of a complex 3D structure that follows specific patterns and possesses a hierarchical organization. Currently, genomics is becoming &ldquo;four-dimensional&rdquo;: our attention is increasingly focused on the study of chromatin dynamics over time, in the fourth dimension. Recent methods for visualizing the movements of chromatin loci in living cells by targeting fluorescent proteins can be divided into two groups. The first group requires the insertion of a special sequence into the locus of interest, to which proteins that recognize the sequence are recruited (e.g., FROS and ParB-INT methods). In the methods of the second approach, &ldquo;programmed&rdquo; proteins are targeted to the locus of interest (i.e., systems based on CRISPR/Cas, TALE, and zinc finger proteins). In the present review, we discuss these approaches, examine their strengths and weaknesses, and identify the key scientific problems that can be studied using these methods

The molecular structure of the DNA fragments eliminated during chromatin diminution in Cyclops kolensis

Presumptive somatic cells of the copepod Cyclops kolensis specifically eliminate a large fraction of their genome by the process of chromatin diminution. The eliminated DNA (eDNA) remains only in the germline cells. Very little is known about the nature of the sequences eliminated from somatic cells. We cloned a fraction of the eDNA and sequenced 90 clones that total 32 kb. The following organizational patterns were demonstrated for the eDNA sequences. All do not contain open reading frames. Each fragment contains 1–3 families of short repeats (10–30 bp) highly homologous within families (87%–100%). Most repeats are separated by spacers up to 50 bp long. Homologous regions were found between fragments, motifs from 15–300 bp in length. Among fragments there occur groups in which the same motifs are ordered in the same fashion. However, spacers between the motifs differ in length and nucleotide composition. Ubiquitous motifs (those occurring in all fragments) were identified. Analysis of motifs revealed submotifs, each occurring within several motifs. Thus, motifs may be regarded as mosaic structures composed of submotifs (short repeats). Taken together, the results provide evidence of a high organizational ordering of the DNA sequences restricted to the germline. With this in mind, it appears incorrect to refer to this part of the genome as junk. Moreover, eDNA is redundant for only the somatic cells—its function is to be sought in germline cells