Chromosome Size Research Articles

Complete Genome Analysis of Rhodococcus opacus S8 Capable of Degrading Alkanes and Producing Biosurfactant Reveals Its Genetic Adaptation for Crude Oil Decomposition.

Microorganisms capable of decomposing hydrophobic substrates in cold climates are of considerable interest both in terms of studying adaptive reactions to low temperatures and in terms of their application in biotechnologies for cleaning up oil spills in a crude-oil polluted soil. The aim of this work was to investigate the genome of Rhodococcus opacus S8 and explore behavior traits of this strain grown in the presence of hexadecane. The genome size of strain S8 is 8.78 Mb, of which the chromosome size is 7.75 Mb. The S8 strain contains 2 circular plasmids of 135 kb and 105 kb and a linear plasmid with a size of 788 kb. The analysis of the genome revealed the presence of genes responsible for the degradation of alkanes and synthesis of biosurfactants. The peculiarities of morphology of microbial cells when interacting with a hydrophobic substrate were revealed. An adaptive mechanism responsible in the absence of oxygen for maintaining the process of degradation of hexadecane is discussed. The data obtained show that the strain S8 has great potential to be used in biotechnologies.

Karyotype analysis of shallot (Allium cepa L.) cultivars from Southeast Sulawesi for breeding programs and sustainable food availability

This research was motivated by the potential sources of genetic diversity of shallot cultivars, originated from several districts in Southeast Sulawesi. Sources of genetic diversity are one of the defining factors of the success of plant breeding programs to develop new cultivars with the desired traits. The purpose of this study was to identify the genetic characteristics of several shallot cultivars from Southeast Sulawesi through Karyotype Analysis. This research was conducted at the Agrotechnology Laboratory, In Vitro Unit, Agriculture Faculty, Halu Oleo University.This research used methods which were according to Carnoy I in fixating, Gertsel in hydrolysing and La Cour in staining the chromosome. The observed variables in this study were chromosome size, centromere index and chromosome shape. Data analysis was determined based on the results of chromosome length measurements using ImageJ software, Photoshop CS3 and Inkscape. The result showed Wakatobi, Konawe and Buton cultivars had different karyotype formulas, while Bombana and Bau-bau cultivars had similar karyotype formulas.

31. Rare familial rearrangement with acrocentric satellite material on Yp relocating to Xp in a female fetus

The short (p) arms of acrocentric chromosomes contain chromatin material described as stalks and satellites made up of repetitive DNA sequences including those encoding ribosomal RNA, and correspond to the nucleolar organizer regions (NOR). Satellites observed on non-acrocentric chromosomes are rare aberrations, typically resulting from translocation between the p-arm of an acrocentric chromosome and the distal arm of another chromosome. The phenotypic consequences of such unbalanced rearrangements can vary significantly depending on the size and gene content of the non-acrocentric chromosome involved.

Linked-Read Sequencing of Eight Falcons Reveals a Unique Genomic Architecture in Flux.

Falcons are diverse birds of cultural and economic importance. They have undergone major lineage-specific chromosomal rearrangements, resulting in greatly reduced chromosome counts relative to other birds. Here, we use 10X Genomics linked reads to provide new high-contiguity genomes for two gyrfalcons, a saker falcon, a lanner falcon, three subspecies of peregrine falcons, and the common kestrel. Assisted by a transcriptome sequenced from 22 gyrfalcon tissues, we annotate these genomes for a variety of genomic features, estimate historical demography, and then investigate genomic equilibrium in the context of falcon-specific chromosomal rearrangements. We find that falcon genomes are not in AT–GC equilibrium with a bias in substitutions toward higher AT content; this bias is predominantly but not exclusively driven by hypermutability of CpG sites. Small indels and large structural variants were also biased toward insertions rather than deletions. Patterns of disequilibrium were linked to chromosomal rearrangements: falcons have lost GC content in regions that have fused to larger chromosomes from microchromosomes and gained GC content in regions of macrochromosomes that have translocated to microchromosomes. Inserted bases have accumulated on regions ancestrally belonging to microchromosomes, consistent with insertion-biased gene conversion. We also find an excess of interspersed repeats on regions of microchromosomes that have fused to macrochromosomes. Our results reveal that falcon genomes are in a state of flux. They further suggest that many of the key differences between microchromosomes and macrochromosomes are driven by differences in chromosome size, and indicate a clear role for recombination and biased gene conversion in determining genomic equilibrium.

Chromosome and ploidy analysis of winter hardy Hibiscus species by FISH and flow cytometry

Determination of nuclear DNA content, genome size, and ploidy level and, information on cytogenetic characteristics are all prerequisite of modern plant breeding. However, identification of individual chromosomes of Hibiscus species is extremely difficult due to high number, small size and similar shape of mitotic chromosomes. The goal of the study was to ascertain the chromosome number, karyomorphology, distribution of 5S and 18S rDNA signals, chromosome length, and centromere positions as well as the ploidy level, genome sizes, 2C - DNA content of winter-hardy Hibiscus (H. syriacus ‘Saejamyung’, H. sinosyriacus ‘Seobong’, H. moscheutos ‘Luna Red’ and, H. paramutabilis). 5S rDNA and 18S rDNA signals were detected by fluorescence in situ hybridization (FISH). According to the FISH results, there are two 5S rDNA signals (green) in H. syriacus, H. sinosyriacus, and H. moscheutos, and four 5S rDNA signals in H. paramutabilis. The range in length of somatic chromosomes in H. syriacus, H. sinosyriacus, H. moscheutos, and H. paramutabilis is 2.66–7.06, 3.18–7.31, 2.91–5.23, and 4.75–7.60, respectively. The 2C - DNA content of H. syriacus, H. sinosyriacus, and H. paramutabilis are very similar, the amount was 4.06, 4.11, and 4.18 pg, respectively whereas, H. moscheutos has nearly half and that amount was 2.06 pg. These findings will contribute to the detailed cytogenetic assessment of Hibiscus and thus benefit plant breeding in this genus.

Kinetochore size scales with chromosome size in bimodal karyotypes of Agavoideae.

In eukaryotes, the total kinetochore size (defined as a chromosomal region containing CENH3-positive nucleosomes) per nucleus strongly correlates with genome size, a relationship that has been hypothesized to stem from general intracellular scaling principles. However, if larger chromosomes within a karyotype required larger kinetochores to move properly, it could also be derived from the mechanics of cell division. We selected seven species of the plant subfamily Agavoideae whose karyotypes are characterized by the presence of small and very large chromosomes. We visualized the kinetochore regions and chromosomes by immunolabelling with an anti-CENH3 antibody and DAPI (6'-diamidino-2-phenylindole) staining. We then employed 2D widefield and 3D super-resolution microscopy to measure chromosome and kinetochore areas and volumes, respectively. To assess the scaling relationship of kinetochore size to chromosome size inside a karyotype, we log-transformed the data and analysed them with linear mixed models which allowed us to control for the inherent hierarchical structure of the dataset (metaphases within slides and species). We found a positive intra-karyotype relationship between kinetochore and chromosome size. The slope of the regression line of the observed relationship (0.277 for areas, 0.247 for volumes) was very close to the theoretical slope of 0.25 for chromosome width based on the expected physics of chromosome passage through the cytoplasm during cell division. We obtained similar results by reanalysing available data from human and maize. Our findings suggest that the total kinetochore size to genome size scaling observed across eukaryotes may also originate from the mechanics of cell division. Moreover, the potential causal link between kinetochore and chromosome size indicates that evolutionary mechanisms capable of leading kinetochore size changes to fixation, such as centromere drive, could promote the size evolution of entire chromosomes and genomes.

Energy-based USV maritime monitoring using multi-objective evolutionary algorithms

This study addresses the monitoring mission problem using an USV equipped with an on-board LiDAR allowing to monitor regions inside its coverage radius. The problem is formulated as a bi-objective coverage path planning with two conflicting objectives : minimization of the consumed energy and maximization of the coverage rate. To solve the problem, we use two popular multi-objective evolutionary algorithms : Non-Dominated Sorting Genetic Algorithm II (NSGA-II) and Pareto Archived Evolution Strategy (PAES). First, we compare the efficiency of these two algorithms and show that PAES allows to find solutions allowing to save more energy as compared to those provided by NSGA-II. Then, we propose a new method which improves the performance of evolutionary algorithms when solving covering path planning problems by reducing the chromosome size. We have applied this method on the used algorithms and simulation results shows a significant performance enhancement both PAES and NSGA-II.

Complete Genome Sequences of Four Strains ofErwiniatracheiphila: A Resource for Studying aBacterial Plant Pathogen with a Highly Complex Genome.

Complete Genome Sequences of Four Strains ofErwiniatracheiphila: A Resource for Studying aBacterial Plant Pathogen with a Highly Complex Genome.

Genomes, repeatomes and interphase chromosome organization in the meadowfoam family (Limnanthaceae, Brassicales)

SUMMARYThe meadowfoam family (Limnanthaceae) is one of the smallest and genomically underexplored families of the Brassicales. The Limnanthaceae harbor about seven species in the genus Limnanthes (meadowfoam) and Floerkea proserpinacoides (false mermaidweed), all native to North America. Because all Limnanthes and Floerkea species have only five chromosome pairs, i.e., a chromosome number rare in Brassicales and shared with Arabidopsis thaliana (Arabidopsis), we examined the Limnanthaceae genomes as a potential model system. Using low‐coverage whole‐genome sequencing data, we reexamined phylogenetic relationships and characterized the repeatomes of Limnanthaceae genomes. Phylogenies based on complete chloroplast and 35S rDNA sequences corroborated the sister relationship between Floerkea and Limnanthes and two major clades in the latter genus. The genome size of Limnanthaceae species ranges from 1.5 to 2.1 Gb, apparently due to the large increase in DNA repeats, which constitute 60–70% of their genomes. Repeatomes are dominated by long terminal repeat retrotransposons, while tandem repeats represent only less than 0.5% of the genomes. The average chromosome size in Limnanthaceae species (340–420 Mb) is more than 10 times larger than in Arabidopsis (32 Mb). A three‐dimensional fluorescence in situ hybridization analysis demonstrated that the five chromosome pairs in interphase nuclei of Limnanthes species adopt the Rabl‐like configuration.

The rambutan (Nephelium lappaceum L.) chromosomes

Abstract. Putri IIS, Yuniastuti E, Parjanto. 2022. The rambutan (Nephelium lappaceum L.) chromosomes. Biodiversitas 23: 2196-2202. Rambutan (Nephelium lappaceum L.) is an annual plant with a wide distribution, it generates this plant to have diversity. The diversity is more often found in morphological characters, in this case, its genetics has not been discovered. The genetics of rambutan could also be indicated by its chromosome karyotype. This research was conducted using the squashing method. The genetic material used was four rambutan varieties which are: Ace, Binjai, Lebak Bulus, and Rapiah. For each variety, the study process will be repeated three times. The results of the study showed rambutan chromosome number in all varieties was 22 chromosomes (2n=22) with an average chromosome size of Ace was 1.777±0.363 µm, followed by Binjai was 1.477±0.392 µm, Lebak Bulus was 1.418±0.320 µm, and Rapiah was 1.443±0.315 µm, and the chromosome shape is metacentric. The karyotype formula obtained was 2n=2x=22=11m.

Chromosome size affects sequence divergence between species through the interplay of recombination and selection.

The structure of the genome shapes the distribution of genetic diversity and sequence divergence. To investigate how the relationship between chromosome size and recombination rate affects sequence divergence between species, we combined empirical analyses and evolutionary simulations. We estimated pairwise sequence divergence among 15 species from three different mammalian clades—Peromyscus rodents, Mus mice, and great apes—from chromosome‐level genome assemblies. We found a strong significant negative correlation between chromosome size and sequence divergence in all species comparisons within the Peromyscus and great apes clades but not the Mus clade, suggesting that the dramatic chromosomal rearrangements among Mus species may have masked the ancestral genomic landscape of divergence in many comparisons. Our evolutionary simulations showed that the main factor determining differences in divergence among chromosomes of different sizes is the interplay of recombination rate and selection, with greater variation in larger populations than in smaller ones. In ancestral populations, shorter chromosomes harbor greater nucleotide diversity. As ancestral populations diverge, diversity present at the onset of the split contributes to greater sequence divergence in shorter chromosomes among daughter species. The combination of empirical data and evolutionary simulations revealed that chromosomal rearrangements, demography, and divergence times may also affect the relationship between chromosome size and divergence, thus deepening our understanding of the role of genome structure in the evolution of species divergence.

Production of new wheat-A. cristatum translocation lines with modified chromosome 2P coding for powdery mildew and leaf rust resistance.

Agropyron cristatum (L.) Gaertn. (2n = 28, PPPP), a relative of wheat, carries desirable genes associated with high yield, disease resistance, and stress resistance, which is an important resource for wheat genetic improvement. The long arm of A. cristatum chromosome 2P carries favorable genes conferring powdery mildew and leaf rust resistance, and two wheat-A. cristatum 2P translocation lines, 2PT3 and 2PT5, with a large segment of 2P chromatin were obtained. In this study, 2PT3 and 2PT5 translocation lines with powdery mildew and leaf rust resistance genes were used to induce translocations of different chromosomal sizes via ionizing radiation. According to cytological characterization, 10 of those plants were new wheat-A. cristatum 2P small-chromosome segment translocation lines with reduced 2P chromatin, and 6 plants represented introgression lines without visible 2P chromosomal fragments. Moreover, four lines were resistant to both powdery mildew and leaf rust, while two lines were resistant only to leaf rust.

Detection of tet(X6) variant–producing Proteus terrae subsp. cibarius from animal cecum in Zhejiang, China

The prevalence of tet(X) genes threatens the clinical use of last-line tigecycline. The tet(X6) gene has been reported in Proteus strains, but its genetic context is rarely reported. This study aimed to investigate the prevalence and genetic contexts of tet(X6) gene in Proteus spp. A tet(X6) variant-bearing P. terrae subsp. cibarius strain was subjected to susceptibility testing, determination of growth curves, scanning electron microscopy, transmission electron microscopy and whole-genome sequencing (WGS). The genomic contexts of the tet(X6)-positive strain were analysed by sequence comparison and annotation. ZJ19PC, a P. terrae subsp. cibarius strain harbouring the tet(X6) variant, was isolated from 20 cecum samples collected in Zhejiang, China. The chromosome size of ZJ19PC was 3 952 084 bp; the GC content was 38.2%; and hugA, sul2, tet(H), floR, dfra1, aadA1, aac(3)-IV and aph(4)-la were found in addition to the tet(X6) variant. Proteus spp. could be classified into three groups based on the tet(X6) gene contexts. Strain ZJ19PC belongs to group 1 (sra-sul2-ISCR2-floR-ISCR2-floR-ISCR2- tet(X6) variant-tnpA-ISEc59-aph(4)-la-aac(3)-Iva-IS26), and this region of group 1 was inserted between modA and guaA. The common antimicrobial resistance (AMR) genes of the three types of AMR gene islands were sul2, floR, tet(X6) and aac(3). The tet(X6) gene contexts and SNP tree showed that ZJ19PC was homologous to HNCF44W and HNCF43W, which indicated that these strains may be clonally transmitted. This study analysed the genetic contexts of the tet(X6) gene in Proteus spp. and highlighted the significance of monitoring tigecycline-resistant P. terrae subsp. cibarius.

TAQing2.0 for genome reorganization of asexual industrial yeasts by direct protein transfection

Genomic rearrangements often generate phenotypic diversification. We previously reported the TAQing system where genomic rearrangements are induced via conditional activation of a restriction endonuclease in yeast and plant cells to produce mutants with marked phenotypic changes. Here we developed the TAQing2.0 system based on the direct delivery of endonucleases into the cell nucleus by cell-penetrating peptides. Using the optimized procedure, we introduce a heat-reactivatable endonuclease TaqI into an asexual industrial yeast (torula yeast), followed by a transient heat activation of TaqI. TAQing2.0 leads to generation of mutants with altered flocculation and morphological phenotypes, which exhibit changes in chromosomal size. Genome resequencing suggested that torula yeast is triploid with six chromosomes and the mutants have multiple rearrangements including translocations having the TaqI recognition sequence at the break points. Thus, TAQing2.0 is expected as a useful method to obtain various mutants with altered phenotypes without introducing foreign DNA into asexual industrial microorganisms.

Dual-color fluorescence in situ hybridization with combinatorial labeling probes enables a detailed karyotype analysis of Saccharina japonica

Saccharina japonica is an economically and ecologically important alga. In recent decades, cytogenetic researches have promoted the large-scale farming of this kelp. However, no reliable cytological landmarks have been developed to distinguish chromosomes and help establish the precise karyotype of S. japonica. In this study, the simple sequence repeat (SSR) (GCT)7 motif with high occupancy level and polymorphism, and a specific SSR (GCT)7 were screened from the genome of S. japonica with all together bioinformatics tools. The existence of (GCT)7 motif and the specific SSR (GCT)7 in the genomic DNA of S. japonica were verified by PCR and southern blot analyses. Fluorescence in situ hybridization (FISH) analysis of the specific SSR (GCT)7 demonstrated that it was stably inherited and co-dominant. With the combined probes of SSR (GCT)7 motif and telomere DNA repeats, dual FISH was conducted for the karyotyping analysis of S. japonica. In agreement with the bioinformatics analysis results, FISH signals of the probe of (GCT)7 motif distributed on all the metaphase chromosomes of the gametophyte of S. japonica with different patterns, and 31 chromosomes were identified. Correspondingly, 31 pairs of homologous chromosomes were distinguished in the sporophyte of S. japonica on the basis of the co-localization of probes of (GCT)7 motif and telomere DNA repeats, as well as the size of metaphase chromosomes. This is the first report of the precise karyotype of S. japonica, which would contribute to the genomic physical mapping and the further genetic breeding of this important brown alga.

Karyotype analysis of two oribatid mite species (Acari: Oribatida)

The chromosomal parameters and karyotypic relationships may provide very valuable information about speciation and karyotype evolution. In the order Oribatida, the chromosomal data are limited to a few reports. In the present study, the chromosomal data of two species are provided for the first time. The diploid chromosome numbers are 2n = 14 in Oribotritia hermanni Grandjean, 1967 (Oribatida: Oribotritiidae) and 2n = 22 in Hermanniella gibber Kulijev, 1979 (Oribatida: Hermanniellidae) and chromosomes are small holocentric chromosomes. The smallest and largest chromosome sizes are 0.38 μm and 1.08 μm in O. hermanni, respectively. The total haploid chromosome length is 4.88 μm, in O. hermanni, and a higher value of 6.98 μm is recorded in H. gibber. The sex chromosomes could not be identified, because the oribatid mites show weak sexual dimorphism. In this respect, the results of the study provide important contributions to the cytotaxonomy of oribatid mites.

Genome size evolution of the extant lycophytes and ferns

Ferns and lycophytes have remarkably large genomes. However, little is known about how their genome size evolved in fern lineages. To explore the origins and evolution of chromosome numbers and genome size in ferns, we used flow cytometry to measure the genomes of 240 species (255 samples) of extant ferns and lycophytes comprising 27 families and 72 genera, of which 228 species (242 samples) represent new reports. We analyzed correlations among genome size, spore size, chromosomal features, phylogeny, and habitat type preference within a phylogenetic framework. We also applied ANOVA and multinomial logistic regression analysis to preference of habitat type and genome size. Using the phylogeny, we conducted ancestral character reconstruction for habitat types and tested whether genome size changes simultaneously with shifts in habitat preference. We found that 2C values had weak phylogenetic signal, whereas the base number of chromosomes (x) had a strong phylogenetic signal. Furthermore, our analyses revealed a positive correlation between genome size and chromosome traits, indicating that the base number of chromosomes (x), chromosome size, and polyploidization may be primary contributors to genome expansion in ferns and lycophytes. Genome sizes in different habitat types varied significantly and were significantly correlated with habitat types; specifically, multinomial logistic regression indicated that species with larger 2C values were more likely to be epiphytes. Terrestrial habitat is inferred to be ancestral for both extant ferns and lycophytes, whereas transitions to other habitat types occurred as the major clades emerged. Shifts in habitat types appear be followed by periods of genomic stability. Based on these results, we inferred that habitat type changes and multiple whole-genome duplications have contributed to the formation of large genomes of ferns and their allies during their evolutionary history.

CNViz: An R/Shiny Application for Interactive Copy Number Variant Visualization in Cancer

Copy number variants (CNVs) comprise a class of mutation which includes deletion, duplication, or amplification events that range in size from smaller than a single-gene or exon, to the size of a full chromosome. These changes can affect gene expression levels and are thus implicated in disease, including cancer. Although a variety of tools and methodologies exist to detect CNVs using data from massively parallel sequencing (also referred to as next-generation sequencing), it can be difficult to appreciate the copy number profile in a list format or as a static image. CNViz is a freely accessible R/Bioconductor package that launches an interactive R/Shiny visualization tool to facilitate review of copy number data. As inputs, it requires genomic locations and corresponding copy number ratios for probe, gene, and/or segment-level data. If supplied, loss of heterozygosity (LOH), focal variant data [single nucleotide variants (SNVs) and small insertions and deletions (indels)], and metadata (e.g., specimen purity and ploidy) can also be incorporated into the visualization. The CNViz R/Bioconductor package is an easy-to-use tool built with the intent of encouraging visualization and exploration of copy number variation. CNViz can be used in a clinical setting as well as for research to study patterns in human cancers more broadly. The intuitive interface allows users to visualize the copy number profile of a specimen, dynamically change resolution to explore gene and probe-level copy number changes, and simultaneously integrate LOH, SNV, and indel findings. CNViz is available for download as an R package via Bioconductor. An example of the application is available at rebeccagreenblatt.shinyapps.io/cnviz_example.

Molecular Tools for Leveraging the Potential of the Acid-Tolerant Yeast Zygosaccharomyces bailii as Cell Factory.

Microorganisms offer a tremendous potential as cell factories, and they are indeed beenused by humans since the previous centuries for biotransformations. Among them, yeasts combine the advantage of aunicellular state with a eukaryotic organization. Moreover, in the era of biorefineries, their biodiversity can offer solutions to specific process constraints. Zygosaccharomyces bailii, an ascomycete budding yeast, is widely known for its peculiar tolerance to different stresses, among which are organic acids. Moreover, the recent reclassification of the species, including diverse hybrids, is further expanding both fundamental and applied interests. It is therefore reasonable that despite the possibility to apply with this yeast some of the molecular tools and protocols routinely used to manipulate Saccharomyces cerevisiae, adjustments and optimizations are necessary. Here we describe in detail the methods for determining chromosome number, size, and aneuploidy, transformation, classical target gene disruption or gene integration, and designing of episomal expression plasmids helpful for engineering the yeast Z. bailii .

Complete genome sequence of Lactiplantibacillus plantarum ST, a potential probiotic strain with antibacterial properties.

Lactiplantibacillus plantarum (L. plantarum) ST was isolated from De’ang pickled tea in Yunnan Province, China. The genomes of strain ST were fully sequenced and analyzed using the PacBio RS II sequencing system. Our previous study has shown that L. plantarum ST is a potential probiotic strain. It had strong tolerance in the simulated artificial gastrointestinal tract, and in the antagonism tests, this strain showed strong antibacterial activity. Therefore, as a probiotic, it may be used in animal breeding. L. plantarum ST genome was composed of 1 circular chromosome and 7 plasmids. The length of the whole genome was 3320817 bp, and the annular chromosome size was 3058984 bp, guanine + cytosine (G ± C) content (%) was 44.76%, which contained 2945 protein-coding sequences (CDS). This study will contribute to a further comprehensive understanding of L. Plantarum ST at the genomic level and provide a theoretical basis for its future application in animal breeding.