Contribution of advanced fluorescence nano microscopy towards revealing mitotic chromosome structure

The organization of chromatin into higher-order structures and its condensation process represent one of the key challenges in structural biology. This is important for elucidating several disease states. To address this long-standing problem, development of advanced imaging methods has played an essential role in providing understanding into mitotic chromosome structure and compaction. Amongst these are two fast evolving fluorescence imaging technologies, specifically fluorescence lifetime imaging (FLIM) and super-resolution microscopy (SRM). FLIM in particular has been lacking in the application of chromosome research while SRM has been successfully applied although not widely. Both these techniques are capable of providing fluorescence imaging with nanometer information. SRM or “nanoscopy” is capable of generating images of DNA with less than 50 nm resolution while FLIM when coupled with energy transfer may provide less than 20 nm information. Here, we discuss the advantages and limitations of both methods followed by their contribution to mitotic chromosome studies. Furthermore, we highlight the future prospects of how advancements in new technologies can contribute in the field of chromosome science.

Karyological and cytogenetic features of conifers in arboretums and parklands

Aim. The study of karyological and cytogenetic features of conifers growing under conditions of introduction and increased recreational pressure, to identify biodiversity and solve the problems of population and environmental genetics of representatives of this group of plants. Methods. Classical chromosome research methods with staining with acetohematoxylin were used. Results. In species, forms, and cultivars of conifers from the Pinaceae and Cupressaceae families growing in arboretums and parklands, as well as being components of green spaces in settlements of different geographical regions, variability of chromosome numbers (mixoploidy), the appearance of B chromosomes, high occurrence, and a wide range of chromosomal and meiotic anomalies are discovered. Conclusions. Karyological and cytogenetic studies have shown the presence of karyotypic polymorphism and an increase in the number of various disorders of mitosis and meiosis in conifers when introduced under growing conditions in recreational areas. Keywords: conifers, introduction, chromosome number, chromosomal rearrangements, meiosis disorders.

Addressing Long-Standing Questions with Advanced Approaches: The 4th B Chromosome Conference

B chromosomes (Bs) are enigmatic accessory genomic elements extensively characterized in diverse eukaryotes. Since their discovery in the beginning of the 20th century, B chromosomes have been the subject of investigation in laboratories all around the world. As a consequence, scientific meetings have dealt with B chromosomes, including the most specific and important conference in the field, “The B Chromosome Conference.” The 4th B Chromosome Conference (4BCC) took place in Botucatu, Brazil, in 2019 and was an excellent opportunity to discuss the latest developments in the B chromosome research field. B chromosome science has advanced from classical and molecular cytogenetics to genomics and bioinformatics approaches. The recent advances in next-generation sequencing technologies and high-throughput molecular biology protocols have led Bs to be the subject of massive data analysis, thus enabling the investigation of structural and functional issues not considered before. Although extensive progress has been made, questions are still remaining to be answered. The advances in functional studies based on RNA, epigenetics, and gene ontologies open the perspective to a better understanding of the complex biology of B chromosomes.

Chromosome Research using Laplacian Based Centromere Detection

The morphology and lengths of chromosomes can change altogether between different development conditions and cytogenetic arrangements. Detection of honest basic chromosome abnormalities at high determination requires systems, (for example, expansion of DNA intercalating operators, diminished introduction to colcemid, cell cycle synchronization, 3–4 days lymphocyte culture) that decline chromosome buildup or capture chromosomes at Pro-meta phase. This paper proposed structure and development of a proficient chromosome investigation methodology and their four different sorts of phases.

Physical organization of repetitive sequences and chromosome diversity of barley revealed by fluorescence in situ hybridization (FISH)

Fluorescence in situ hybridization (FISH) using oligonucleotides is a simple and convenient method for chromosome research. In this study, 34 of 46 previously developed oligonucleotides produced signals in barley. Together with two plasmid clones and one PCR-amplified cereal centromere repeat (CCS1) probe, 37 repetitive sequences were chromosomally located produced three types of signals covering different positions on the chromosomes. The centromeric and pericentric regions had a more complex genomic organization and sequence composition probably indicative of higher contents of heterochromatin. An efficient multi-plex probe containing eight oligonucleotides and a plasmid clone of 45S rDNA was developed. Thirty-three barley karyotypes were developed and compared. Among them, 11 irradiation-induced mutants of cultivar 08-49 showed no chromosomal variation, whereas 22 cultivar and landrace accessions contained 28 chromosomal polymorphisms. Chromosome 4H was the most variable and 6H was the least variable based on chromosome polymorphic information content (CPIC). Five polymorphic chromosomes (1H-2, 2H-1, 3H-3, 5H-2, and 6H-2) were dominant types, each occurring in more than 50% of accessions. The multi-plex probe should facilitate identification of further chromosomal polymorphisms in barley.

Highlight on fusing multiple chromosomes in yeast into a single chromosome

Multiple biological mysteries remain in the definition and organization of genetic information into different chromosomes. Up to now, genome architecture at the chromosome level remain enigmatic concerning the reasons why evolution and natural selection arranged genetic information in separate segments in eukaryotic cells as compared to the single chromosome in the prokaryotic world. Specifically, one important unresolved question has been the role of chromosomes in cellular physiology and biochemical processes. By deleting the centromere and telomere regions of different chromosomes in Saccharomyces cerevisiae and fusing the different chromosomes into one chromosome, research reported by Shao and coworkers in Nature revealed the technical possibility of concatenating all genetic information into one segment. Furthermore, cell viability assays revealed that there was no significant loss of cell viability after the fusing of 16 chromosomes into a single chromosome. This highlighted that centromere and telomere sequences were not critical to overall cellular function, physiology and biochemistry. More importantly, the results highlighted that genetic information and its organisation at the sub-chromosome level play a more important role in defining cellular biochemical processes and physiology such as metabolism and cell division processes. Collectively, the technical feasibility of fusing multiple chromosomes into a single chromosome has been shown in new research that deleted the centromere and telomere regions of different chromosomes for fusing the resulting genetic information into a single chromosome. Little loss of viability and function in cells with a single chromosome and the stability of replicating the chromosome revealed that centromere and telomere sequences may not play critical roles in defining cellular physiology and biochemistry. More importantly, genomic information and its regulation was shown indirectly to have a more direct influence on cell physiology and metabolism than chromosomal architecture.