Chromosome Types Research Articles

Stalk-eyed flies carrying a driving X chromosome compensate by increasing fight intensity

Exaggerated ornaments provide opportunities to understand how selection can operate at different levels to shape the evolution of a trait. While these features aid their bearer in attracting mates or fending off competitors, they can also be costly and influenced by the environment and genetic variation. The eyestalks of the stalk-eyed fly, Teleopsis dalmanni, are of interest because eyestalk length is the target of both intra- and intersexual selection and is also reduced by loci on a highly-divergent sex ratio X chromosome (XSR), a meiotic driver accounting for up to 30% of wild X chromosomes. Male stalk-eyed flies fight to control access to females and over food using a combination of low-intensity displays and high-intensity physical fights. We staged, filmed, and scored contests between pairs of eyespan-matched males to evaluate whether X chromosome type impacts the behavior and outcome of aggressive interactions. While our results broadly match expectations from previous studies, we found that XSR males used more high-intensity behaviors than males carrying a non-driving, standard X chromosome (XST), particularly when their eyestalks were of similar size or smaller than their opponents. Additionally, we found that when XSR males use high-intensity behaviors, they win more bouts than when they use low-intensity behaviors. Taken together, these results suggest that XSR impacts male aggressive behavior to compensate for the shorter eyestalks of XSR males and may help to explain how this selfish chromosome is maintained.

Comparative karyological features of several populations of Populus euphratica Oliv., grown under different environmental conditions in Iran

Abstract Understanding genetic structure and chromosomal characteristics is essential for developing effective breeding programmes and improving plant species. This research compared karyotypic features of 10 plant populations of Populus euphratica from various regions of Iran. Fresh roots grown from cuttings of the populations were used to get metaphase cells. Then several chromosomal parameters were recorded and analysed using a nested statistical model. All the studied populations were diploid, with 2n = 38 chromosomes, consisting of medium and sub-medium chromosome types. Significant differences (P ⩽ 0.01) were observed between the plant populations in chromosomal dimensions and arm ratios, suggesting chromosomal rearrangements. Chromosome lengths in the studied populations ranged from 0.69 to 3.38 μm. Intra-chromosomal index (A1) showed clear asymmetrical differences between the plant populations. Furthermore, using Stebbins's standards, the studied populations classified as 1A and 1B classes, demonstrated more asymmetry than those categorized as 1B and 2B, respectively. Cytological differences between the plant populations, collected from different parts of the country, showed that chromosome structural rearrangements are responsible for the speciation and adaption of the species against the mentioned variable ecological conditions and play a key role in response to diverse climatic and geographical conditions.

The formation and propagation of human Robertsonian chromosomes.

Robertsonian chromosomes are a type of variant chromosome found commonly in nature. Present in one in 800 humans, these chromosomes can underlie infertility, trisomies, and increased cancer incidence. Recognized cytogenetically for more than a century, their origins have remained mysterious. Recent advances in genomics allowed us to assemble three human Robertsonian chromosomes completely. We identify a common breakpoint and epigenetic changes in centromeres that provide insight into the formation and propagation of common Robertsonian translocations. Further investigation of the assembled genomes of chimpanzee and bonobo highlights the structural features of the human genome that uniquely enable the specific crossover event that creates these chromosomes. Resolving the structure and epigenetic features of human Robertsonian chromosomes at a molecular level paves the way to understanding how chromosomal structural variation occurs more generally, and how chromosomes evolve.

ST105 Lineage of MRSA: An Emerging Implication for Bloodstream Infection in the American and European Continents.

Sequence-type 5 (ST5) of methicillin-resistant Staphylococcus aureus (MRSA), harboring the staphylococcal chromosomal cassette mec type IV (SCCmecIV), was first detected in Portugal. It emerged as a significant cause of healthcare-associated (HA) infection in pediatric units and was hence named the pediatric clone. Another ST5 lineage, which carries SCCmecII, also prevailed in the USA and Japan for multiple years. More recently, another MRSA lineage, ST105-SCCmecII, part of the evolution of clonal complex 5 (CC5) MRSA, has emerged as the cause of hospital-acquired bloodstream infection outbreaks in countries including Portugal, the USA, and Brazil. This article reviews studies on the epidemiology and evolution of these newly emerging pathogens. To this end, a search of PUBMED from inception to 2024 was performed to find articles reporting the occurrence of ST105 MRSA in epidemiologic studies. A second search was performed to find studies on MRSA, CC5, ST5, and SCCmecII. A search of PUBMED from 1999 to 2024 was also performed to identify studies on the genomics and evolution of ST5, CC5, and ST105 MRSA. Further studies were identified by analyzing the references of the previously selected articles from PUBMED. Most articles on ST105 MRSA were included in this review. Only articles written in English were included. Furthermore, only studies that used a reliable genotyping method (e.g., whole genome sequencing, or MLST) to classify the CC5 lineages were selected. The quality and selection of articles were based on the consensus assessment of the three authors in independent evaluations. In conclusion, ST105-SCCmecII is an emerging MRSA in several countries, being the second/third most important CC5 lineage, with a relatively high frequency in bloodstream infections. Of concern is the increased mortality from BSI in patients older than 15 years and the higher prevalence of ST105-SCCmecII in the blood of patients older than 60 years reported in some studies.

Y and Mitochondrial Chromosomes in the Heterogeneous Stock Rat Population.

Genome-wide association studies typically evaluate the autosomes and sometimes the X Chromosome, but seldom consider the Y or mitochondrial Chromosomes. We genotyped the Y and mitochondrial Chromosomes in heterogeneous stock rats (Rattus norvegicus), an outbred population created from eight inbred strains. We identified 8 distinct Y and 4 distinct mitochondrial Chromosomes among the 8 founders. However, only two types of each nonrecombinant chromosome were observed in our modern heterogeneous stock rat population (generations 81-97). Despite the relatively large sample size, there were virtually no significant associations for behavioral, physiological, metabolome, or microbiome traits after correcting for multiple comparisons. However, both Y and mitochondrial Chromosomes were strongly associated with expression of a few genes located on those chromosomes, which provided a positive control. Our results suggest that within modern heterogeneous stock rats there are no Y and mitochondrial Chromosomes differences that strongly influence behavioral or physiological traits. These results do not address other ancestral Y and mitochondrial Chromosomes that do not appear in modern heterogeneous stock rats, nor do they address effects that may exist in other rat populations, or in other species.

A Unique Derivative Chromosome 4 with a Predominant 4p16.3 Microduplication Phenotype and a Literature Review

Introduction: Constitutional structural abnormalities affecting chromosome 4 result in variable distinct phenotypic traits including duplication 4p syndrome, deletion 4p or Wolf-Hirschhorn syndrome (WHS), deletion 4q and duplication 4q syndromes. Complex rearrangements involving both chromosome 4 arms are very rarely reported with different break points occurring within regions of 4p13-p16 and 4q32-35. They most commonly occur in familial cases due to parental pericentric inversion resulting in a recombinant chromosome 4 “rec(4).” The clinical picture is dependent on the size and type of copy number imbalance and the genes involved. Methods: We report on a female patient with delayed developmental milestones and lower limb anomalies, who carried a de novo unique type of complex rearrangement affecting both chromosome 4 arms, diagnosed by karyotype and fluorescence in situ hybridization analysis and chromosomal microarray (CMA). Results: The chromosome 4 rearrangement involved three copy number alterations, consisting of a terminal 1.17 Mb 4p16.3 deletion with a contiguous proximal 1.8 Mb 4p16.3 duplication, including the Wolf-Hirschhorn critical (WHSC) region, and an inverted 27 Mb terminal 4q32-35.2 duplication attached to terminal 4p. The patient’s predominant phenotype was consistent with 4p16.3 microduplication syndrome. The rearrangement occurred as a de novo abnormality, and thus it was designated as a derivative chromosome 4. To the best of our knowledge, this complex type of chromosome 4 rearrangement has not been reported so far. Conclusion: The present report adds to the scarce 4p16.3 microduplication syndrome reports and emphasizes the role of WHSC region in the syndromic phenotype. It also reveals the importance of CMA in detecting subtle copy number variations (CNVs) that could be dominantly reflected on the phenotype, which is very important in patients’ management and family counselling.

Naturally occurring horse model of miscarriage reveals temporal relationship between chromosomal aberration type and point of lethality

Chromosomal abnormalities are a common cause of human miscarriage but rarely reported in any other species. As a result, there are currently inadequate animal models available to study this condition. Horses present one potential model since mares receive intense gynecological care. This allowed us to investigate the prevalence of chromosomal copy number aberrations in 256 products of conception (POC) in a naturally occurring model of pregnancy loss (PL). Triploidy (three haploid sets of chromosomes) was the most common aberration, found in 42% of POCs following PL over the embryonic period. Over the same period, trisomies and monosomies were identified in 11.6% of POCs and subchromosomal aberrations in 4.2%. Whole and subchromosomal aberrations involved 17 autosomes, with chromosomes 3, 4, and 20 having the highest number of aberrations. Triploid fetuses had clear gross developmental anomalies of the brain. Collectively, data demonstrate that alterations in chromosome number contribute to PL similarly in women and mares, with triploidy the dominant ploidy type over the key period of organogenesis. These findings, along with highly conserved synteny between human and horse chromosomes, similar gestation lengths, and the shared single greatest risk for PL being advancing maternal age, provide strong evidence for the first animal model to truly recapitulate many key features of human miscarriage arising due to chromosomal aberrations, with shared benefits for humans and equids.

Genome-wide identification and expression profiling of growth‑regulating factor (GRF) and GRF‑interacting factor (GIF) gene families in chickpea and pigeonpea

The growth-regulating factor (GRF) and GRF-interacting factor (GIF) families encode plant-specific transcription factors and play vital roles in plant development and stress response processes. Although GRF and GIF genes have been identified in various plant species, there have been no reports of the analysis and identification of the GRF and GIF transcription factor families in chickpea (Cicer arietinum) and pigeonpea (Cajanus cajan). The present study identified seven CaGRFs, eleven CcGRFs, four CaGIFs, and four CcGIFs. The identified proteins were grouped into eight and three clades for GRFs and GIFs, respectively based on their phylogenetic relationships. A comprehensive in-silico analysis was performed to determine chromosomal location, sub-cellular localization, and types of regulatory elements present in the putative promoter region. Synteny analysis revealed that GRF and GIF genes showed diploid-polyploid topology in pigeonpea, but not in chickpea. Tissue-specific expression data at the vegetative and reproductive stages of the plant showed that GRFs and GIFs were strongly expressed in tissues like embryos, pods, and seeds, indicating that GRFs and GIFs play vital roles in plant growth and development. This research characterized GRF and GIF families and hints at their primary roles in the chickpea and pigeonpea growth and developmental process. Our findings provide potential gene resources and vital information on GRF and GIF gene families in chickpea and pigeonpea, which will help further understand the regulatory role of these gene families in plant growth and development.

P-534 Toward enhanced genetic counseling with PGT-SR: exploring the impact of chromosomal rearrangement type and carrier gender on the acquisition of transferable embryos

Abstract Study question Do chromosomal rearrangement type and gender of carriers influence the ability to obtain transferable embryos? Summary answer Carriers of a reciprocal translocation, particularly female carriers, could have a higher risk of having non-transferable embryos. What is known already Chromosomal translocations are common structural rearrangements in the general population, occurring even 10 times more frequently in the infertile population, as carriers may produce unbalanced chromosomal gametes. Preimplantation Genetic Testing for Structural Rearrangements (PGT-SR) is a crucial tool for selecting embryos to transfer. There are numerous factors that can affect the availability of transferable embryos, and some of the less studied ones are the gender of the carrier and the type of chromosomal rearrangement. Study design, size, duration This is a single-center retrospective study performed between 2016 and 2023, that included 265 biopsies. Embryos were classified as transferable (n = 80, 30%) if they were euploid/balanced or exhibited low-grade mosaicism (< 50%) without the involvement of chromosomes 13, 14, 16, 18, 21, and X. Non-transferable embryos (n = 185, 70%) included those that were unbalanced, aneuploid, or displayed high-grade mosaicism. Differences between groups were assessed using Chi-square and Fisher’s exact tests. Values with p < 0.05* were deemed significant. Participants/materials, setting, methods NGS-based PGT-SR was performed on 265 embryos from 71 cycles of 47 couples. Couples were divided into Robertsonian translocation carrier group (ROB-T, 105 embryos) and Reciprocal translocation carrier group (REC-T, 160 embryos). Subsequently, data was categorized by maternal age: ≤37 (ROB-T=91, REC-T=122) and >37 years (ROB-T=14, REC-T=38), as well as by the gender of the carrier: male carrier group (MC) (ROB-T=77, REC-T=97) and female carrier group (FC) (ROB-T=29, REC-T=74). Main results and the role of chance Of the embryos belonging to ROB-T group, 45/105 (43%) were transferable, while in the REC-T group only 35/160 (22%) were transferable. This difference was statistically significant (p = 0.0004612). It was assessed whether these differences were attributable to maternal age or gender of carriers. In the ≤37, 43% (39/91) of the ROB-T embryos were transferable, but only 25% (30/122) were transferable in the REC-T group (p = 0.007583). In the >37, 43% (6/14) of the ROB-T embryos were transferable versus 13% (5/38) in the REC-T group (p = 0.04951). In both age groups, the obtaining transferable embryos were influenced by the type of translocation. In the MC group, 47% (36/76) of the ROB-T embryos were transferable and only 24% (22/90) were transferable in the REC-T group (p = 0.003467). In the FC group, 31% (9/29) of the ROB-T embryos and 19% (13/70) of the REC-T embryos were transferable (p = 0.2749). In the MC group, the obtaining transferable embryos were influenced by the type of translocation. However, within the FC group, no significant differences were observed. When evaluating non-transferable embryos (185), 71% were unbalanced and 29% were balanced ones with aneuploidies. Unbalanced embryos were more frequent in REC-T carriers in all analyzed groups. Limitations, reasons for caution This study is limited by its retrospective nature and its small sample size. Additionally, it is worth noting the difference in sample size between groups when segmenting the data by maternal age. Wider implications of the findings Our results indicate that the type of rearrangement is relevant in obtaining transferable embryos. Carriers of REC-T, especially female carriers, could have a higher risk of having non-transferable embryos compared to carriers of ROB-T. These findings could be significant for genetic counseling of individuals carrying chromosomal translocations. Trial registration number Not applicable

A healthy live birth after mosaic blastocyst transfer in preimplantation genetic testing for GATA1-related cytopenia combined with HLA matching

BackgroundGATA1-related cytopenia (GRC) is characterized by thrombocytopaenia and/or anaemia ranging from mild to severe. Haematopoietic stem cell transplantation (HSCT) is a healing therapeutic choice for GRC patients. We identified a novel pathogenic variant (GATA1: c.1019delG) in a boy with GATA1-related cytopenia. Then we performed preimplantation genetic testing (PGT) in this GRC family. After a mosaic embryo transfered, a healthy and HLA-compatible with the proband baby was delivered.Case presentationThe proband is a 6-year-old boy who was diagnosed to have transfusion-dependent anaemia since 3 year old. Whole-exome sequencing (WES) showed that the proband has a hemizygous variant c.1019delG in GATA1, which is inherited from his mother. His parents decided to undergo PGT to have a health and HLA-compatible offspring. After whole genome amplification (WGA) of biopsied trophectoderm (TE) cells, next generation sequencing (NGS)-based PGT was preformed to analyse embryos on chromosomal aneuploidy, target mutation and HLA typing. There were 3 embryos HLA-matched to the proband. The genotypes of the 3 embryos were heterozygous variant, hemizygous variant, normal respectively. After a heterozygous, mosaic partial trisomy (chr)16, and HLA-matched embryo transfer, a healthy baby was delivered and whose HSCT is compatible with the proband.ConclusionsNGS-based PGT-HLA is a valuable procedure for the treatment of GATA1-related cytopenia caused by GATA1 variants, or other haematological disorders, oncological and immunological diseases. Furthermore, our study reconfirms that mosaic embryos transfer would bring healthy offspring.

P-525 Is there an impact of chromosomal structural rearrangements on IVF laboratory outcomes in PGT-SR cycles? a propensity score matching-based study

Abstract Study question Are IVF laboratory outcomes altered in PGT-SR cycles, and how are these outcomes affected by the type of rearrangement and the carrier’s gender? Summary answer PGT-SR cycles showed a decrease in overall blastulation and top-quality blastocyst rates compared to PGT-A cycles. Transferable blastocyst rate correlates with chromosomal structural rearrangement type. What is known already Chromosomal structural rearrangements (SR) are associated with altered gametogenesis, resulting in the formation of gametes with chromosomal imbalances. For affected couples, undergoing IVF cycles with PGT-SR is recommended to select embryos with a normal or balanced karyotype. Scarce data exist on IVF laboratory outcomes in couples undergoing PGT-SR cycles. Findings regarding blastocyst rate, mainly focused on high-quality blastocysts, remain unclear. In addition, structural rearrangement carriers yield fewer transferable blastocysts than patients undergoing PGT-A. Conclusive evidence regarding the influence of carrier gender and type of chromosomal SR on the development of transferable blastocysts is lacking, with existing studies yielding contradictory results. Study design, size, duration This retrospective cohort study was conducted at a single university-affiliated obstetrics and fertility center between January 2019 and November 2023. The analysis involved 558 patients undergoing IVF cycles, including 136 in PGT-SR and 422 in PGT-A cycles. Participants/materials, setting, methods Trophectoderm biopsies from day 5/6/7 blastocysts underwent comprehensive chromosome screening utilizing validated NGS. Propensity Score Matching with a 1:1 match ratio was performed to balance baseline characteristics between the PGT-SR and PGT-A groups. The impact of chromosomal structural rearrangements on laboratory outcomes was assessed using a logistic regression model. Subsequently, within the PGT-SR population, the association between the carrier’s gender and the transferable blastocyst rate was evaluated through logistic regression, adjusting for potential confounders. Main results and the role of chance There was no significant difference in the fertilization rate between the PGT-A and PGT-SR groups (OR = 1.26, 95% CI 1.01-1.60, p-value=0.14). However, the PGT-SR group exhibited a significantly lower overall blastulation rate (36.7%) compared to the PGT-A group (42.8%) (OR = 0.76, 95% CI 0.63-0.93, p-value=0.03). Notably, a significant difference was observed in the top-quality blastocyst rate, with PGT-A patients showing a rate of 21.7% versus 9.57% in PGT-SR patients (OR = 0.45, 95% CI 0.29-0.69, p-value<0.01). In the PGT-SR cohort, female carriers constituted 44.1%, while male carriers were 56.6%. Reciprocal translocations represented 56.5% of the structural rearrangements, with the remaining 43.5% being other types. When comparing female to male carriers, no significant association was observed between the transferable blastocyst rate and the carrier’s gender (OR = 0.90, 95% CI = 0.35-2.31, p-value=0.83). However, a notable association was identified between the transferable blastocyst rate and the type of structural chromosomal rearrangements (OR = 0.16, 95% CI = 0.09-0.29, p-value<0.01). Specifically, in cases where the patient carried a chromosomal SR other than reciprocal translocation, the transferable blastocyst rate was 83.2%, in contrast to 44.9% in patients with reciprocal translocations. Limitations, reasons for caution The retrospective design of this study represents a limitation, and the limited sample size of patients with structural chromosomal rearrangements restricts the statistical power. Wider implications of the findings These findings reveal that patients with SR yield fewer embryos for biopsy than those undergoing PGT-A, showing a reduced rate of transferable blastocysts in cases of reciprocal translocations. Consequently, providing comprehensive counseling and managing expectations for couples undergoing PGT-SR is essential. Trial registration number not applicable

A simple BLASTn-based approach generates novel insights into the regulation and biological function of type I toxin-antitoxins.

Bacterial chromosomal type I toxin-antitoxin systems consist of a small protein, typically under 60 amino acids, and a small RNA (sRNA) that represses toxin translation. These gene pairs have gained attention over the last decade for their contribution to antibiotic persistence and phage tolerance in bacteria. However, biological functions for many remain elusive as gene deletions often fail to produce an observable phenotype. For many pairs, it is still unknown when the toxin and/or antitoxin gene are natively expressed within the bacterium. We examined sequence conservation of three type I toxin-antitoxin systems, tisB/istR-1, shoB/ohsC, and zor/orz, in over 2,000 Escherichia coli strains, including pathogenic and commensal isolates. Using our custom database, we found that these gene pairs are widespread across E. coli and have expression potential via BLASTn. We identified an alternative, dominant sequence variant of TisB and confirmed that it is toxic upon overproduction. Additionally, analyses revealed a highly conserved sequence in the zorO mRNA untranslated region that is required for full toxicity. We further noted that over 30% of E. coli genomes contain an orz antitoxin gene only and confirmed its expression in a representative strain: the first confirmed report of a type I antitoxin without its cognate toxin. Our results add to our understanding of these systems, and our methodology is applicable for other type I loci to identify critical regulatory and functional features.IMPORTANCEChromosomal type I toxin-antitoxins are a class of genes that have gained increasing attention over the last decade for their roles in antibiotic persistence which may contribute to therapeutic failures. However, the control of many of these genes and when they function have remained elusive. We demonstrate that a simple genetic conservation-based approach utilizing free, publicly available data yields known and novel insights into the regulation and function of three chromosomal type I toxin-antitoxins in Escherichia coli. This study also provides a framework for how this approach could be applied to other genes of interest.

Dynamic chromosome association with nuclear organelles in living cells.

The development of progressively sophisticated tools complemented by the integration of live cell imaging enhances our understanding of the four-dimensional (4D) nucleome, revealing elaborate molecular interactions and chromatin states. Yet, the dynamics of chromosomes in relation to nuclear organelles or to each other across cell cycle in living cells are underexplored. We have developed photoconvertible GFP H3-Dendra2 stably expressing in PC3M cells. The nuclear lamina and perinucleolar associated heterochromatin or diffuse chromosome regions were photoconverted through a single-point activation using a confocal microscope. The results demonstrated a dynamic nature for both types of chromosomes in the same cell cycle and across mitosis. While some chromosome domains were heritably associated with either nuclear lamina or nucleoli, others changed alliance to different nuclear organelles postmitotically. In addition, co-photoconverted chromosome domains often do not stay together within the same cell cycle and across mitosis, suggesting a transient nature of chromosome neighborhoods. Long-range spreading and movement of chromosomes were also observed. Interestingly, when cells were treated with a low concentration of actinomycin D that inhibits Pol I transcription through intercalating GC-rich DNA, chromosome movement was significantly blocked. Treatment with another Pol I inhibitor, metarrestin, which does not impact DNA, had little effect on the movement, suggesting that the DNA structure itself plays a role in chromosome dynamics. Furthermore, inhibition of Pol II transcription with α-amanitin also reduced the chromosome movement, demonstrating that Pol II, but not Pol I transcription, is important for chromosome dynamics in the nucleus.

Cytological Studies in the Genus <i>Amaryllis</i>

One species and eight horticultural varieties of Amaryllis show a basic number of x=11, which is the predominant basic number of the family. In both Amaryllis belladonna and Amaryllis-Mrs. Garfield the normal somatic number is 2n=22. All the seven colour varieties of Amaryllis-Giant Dutch have 2n=44 chromosomes. These varieties differ from one another in the minor alterations of the chromosome types suggesting the role of minor structural alterations in evolution. In addition to the normal somatic complement a number of variant nuclei with altered karyotypes have been recorded.

Type I toxin-antitoxin systems in bacteria: from regulation to biological functions.

Toxin-antitoxin systems are ubiquitous in the prokaryotic world and widely distributed among chromosomes and mobile genetic elements. Several different toxin-antitoxin system types exist, but what they all have in common is that toxin activity is prevented by the cognate antitoxin. In type I toxin-antitoxin systems, toxin production is controlled by an RNA antitoxin and by structural features inherent to the toxin messenger RNA. Most type I toxins are small membrane proteins that display a variety of cellular effects. While originally discovered as modules that stabilize plasmids, chromosomal type I toxin-antitoxin systems may also stabilize prophages, or serve important functions upon certain stress conditions and contribute to population-wide survival strategies. Here, we will describe the intricate RNA-based regulation of type I toxin-antitoxin systems and discuss their potential biological functions.

Cytotaxonomical Studies in the Genus <I>Setcreasea</I>

Cytological studies have been done in two species of Setcreasea. In Setcreasm purpurea a somatic chromosome number of 12 has been observed and in S. brevifolia an aneuploid number of 2n = 25 has been found. Three major types of chromosomes have been observed m the karyotypes of both taxa. The cytological situation in the two taxa has been observed to, be similar to that of Tradescantia. Meiotic behaviour in S. purpurea is regular while in S. brevifolia it is irregular. The irregularity in the latter taxon is doubtless connected with aneuploidy and structural hybridity. The finding of diploid pollen grains in S. purpurea and S. brevifoliacould have been due to the failure of the chromosomes or chromatids to go to different poles, disturbance in spindle formation, or possibly to a complete failure of cell wall development. Many cases have been found of abnormal cvtokinesis in pollen grain formation. Polyploidy, structural hybridity and hybridization has been considered to be playing major role in evolutionary tendencies in Setcreasea.In view of the cytological and morphological characteristics, it has been suggested that the genus is related to Zebrina and its relationship with Cyanotis is remote. Taking all these factors into consideration, it appears that Setcreasea will be in more natural systematic position if separated widely from Cyanotis and placed near Zebrina.

Molecular cytogenetic characterization of 9 populations of four species in the genus Polygonatum (Asparagaceae).

To characterize the chromosomes of the four species of Polygonatum Miller, 1754, used in traditional Chinese medicine, P.cyrtonema Hua, 1892, P.kingianum Collett et Hemsley, 1890, P.odoratum (Miller, 1768) Druce, 1906, and P.sibiricum Redouté, 1811, and have an insight into the karyotype variation of the genus Polygonatum, fluorescence in situ hybridization (FISH) with 5S and 45S rDNA oligonucleotide probes was applied to analyze the karyotypes of 9 populations of the four species. Detailed molecular cytogenetic karyotypes of the 9 populations were established for the first time using the dataset of chromosome measurements and FISH signals of 5S and 45S rDNA. Four karyotype asymmetry indices, CVCI, CVCL, MCA and Stebbins' category, were measured to elucidate the asymmetry of the karyotypes and karyological relationships among species. Comparison of their karyotypes revealed distinct variations in the karyotypic parameters and rDNA patterns among and within species. The basic chromosome numbers detected were x = 9, 11 and 13 for P.cyrtonema, x = 15 for P.kingianum, x = 10 and 11 for P.odoratum, and x = 12 for P.sibiricum. The original basic chromosome numbers of the four species were inferred on the basis of the data of this study and previous reports. All the 9 karyotypes were of moderate asymmetry and composed of metacentric, submetacentric and subtelocentric chromosomes or consisted of two of these types of chromosomes. Seven populations have one locus of 5S rDNA and two loci of 45S rDNA, and two populations added one 5S or 45S locus. The karyological relationships among the four species revealed by comparison of rDNA patterns and PCoA based on x, 2n, TCL, CVCI, MCA and CVCL were basically accordant with the phylogenetic relationships revealed by molecular phylogenetic studies. The mechanisms of both intra- and inter-specific dysploidy in Polygonatum were discussed based on the data of this study and literature.

A sophisticated virulence repertoire and colistin resistance of Citrobacter freundii ST150 from a patient with sepsis admitted to ICU in a tertiary care hospital in Uganda, East Africa: Insight from genomic and molecular docking analyses

Sepsis and multidrug resistance comprise a complex of factors attributable to mortality among intensive care unit (ICU) patients globally. Pathogens implicated in sepsis are diverse, and their virulence and drug resistance remain elusive. From a tertiary care hospital ICU in Uganda, we isolated a Citrobacter freundii strain RSM030 from a patient with sepsis and phenotypically tested it against a panel of 16 antibiotics including imipenem levofloxacin, cotrimoxazole and colistin, among others. We sequenced the organism's genome and integrated multilocus sequencing (MLST), PathogenFinder with Virulence Factor analyzer (VFanalyzer) to establish its pathogenic relevance. Thereafter, we combined antiSMASH and PRISM genome mining with molecular docking to predict biosynthetic gene clusters (BGCs), pathways, toxin structures and their potential targets in-silico. Finally, we coupled ResFinder with comprehensive antibiotic resistance database (CARD) to scrutinize the genomic antimicrobial resistance profile of the isolate. From PathogenFinder and MLST, this organism was confirmed to be a human pathogen (p = 0.843), sequence type (ST)150, whose virulence is determined by chromosomal type III secretion system (T3SS) (the injectosome) and plasmid-encoded type IV secretion system (T4SS), the enterobactin biosynthetic gene cluster and biofilm formation through the pgaABCD operon. Pathway and molecular docking analyses revealed that the shikimate pathway can generate a toxin targeting multiple host proteins including spectrin, detector of cytokinesis protein 2 (Dock2) and plasmalemma vesicle-associated protein (PLVAP), potentially distorting the host cell integrity. From phenotypic antibiotic testing, we found indeterminate results for amoxicillin/clavulanate and levofloxacin, with resistance to cotrimoxazole and colistin. Detailed genome analysis revealed chromosomal beta lactam resistance genes, i.e. blaCMY-79, blaCMY-116 and blaTEM-1B, along with multiple mutations of the lipopolysaccharide modifying operon genes PmrA/PmrB, pmrD, mgrA/mgrB and PhoP/PhoQ, conferring colistin resistance. From these findings, we infer that Citrobacter freundii strain RSM030 is implicated in sepsis and resistance to standard antibiotics, including colistin, the last resort.

Rapid inactivation of antibiotic resistance genes and virulence genes in the building ventilation duct by UV185+254 irradiation

The energy-efficient inactivation of airborne antibiotic resistance genes (ARGs) and virulence genes was seldom investigated in full-scale ventilation systems. This study examined the potential of UV disinfection to inactivate two types of chromosome- or plasmid-encoded ARGs (mecA and amp) and one chromosomal virulence gene (tst1) within two host bacterial species: Staphylococcus aureus and Escherichia coli. UV185+254 disinfection exhibited dual damages (i.e., physical by 254 nm UV and oxidative by the produced ozone) on those target genes, resulting in relatively strong adaptability to temperature and low electrical energy per order in specific gene removal (down to 1 kJ m−3). It was found that the disinfection efficiency of target genes was up to 2 orders of magnitude lower than that of the host bacteria. The target genes with more bases and higher weighted bipyrimidine content were more susceptible to UV185+254 treatment. Thicker cell walls and plasmid carriers prominently hindered UV185+254 deactivation, requiring larger radiation power to enhance the gene removal efficiency in bioaerosols.

Genetic And Environmental Associations Of Nonspecific Chromosomal Aberrations.

Nonspecific structural chromosomal aberrations (CAs) are found in around 1% of circulating lymphocytes from healthy individuals but the frequency may be higher after exposure to carcinogenic chemicals or radiation. CAs have been used in the monitoring of persons exposed to genotoxic agents and radiation. Previous studies on occupationally exposed individuals have shown associations between the frequency of CAs in peripheral blood lymphocytes and subsequent cancer risk. The cause for CA formation are believed to be unrepaired or insufficiently repaired DNA double-strand breaks or other DNA damage, and additionally telomere shortening. CAs include chromosome (CSAs) and chromatid type aberrations (CTAs). In the present review, we first describe the types of CAs, the conventional techniques used for their detection and some aspects of interpreting the results. We then focus on germline genetic variation in the frequency and type of CAs measured in a genome-wide association study (GWAS) in healthy individuals in relation to occupational and smoking-related exposure compared to non-exposed referents. The associations (at p<10-5) on 1473 healthy individuals were broadly classified in candidate genes from functional pathways related to DNA damage response/repair, including PSMA1, UBR5, RRM2B, PMS2P4, STAG3L4, BOD1, COPRS and FTO; another group included genes related to apoptosis, cell proliferation, angiogenesis and tumorigenesis, COPB1, NR2C1, COPRS, RHOT1, ITGB3, SYK, and SEMA6A; a third small group mapped to genes KLF7, SEMA5A and ITGB3 which were related to autistic traits, known to manifest frequent CAs. Dedicated studies on 153 DNA repair genes showed associations for some 30 genes, expression of which could be modified by the implicated variants. We finally point out that monitoring of CAs is so far the only method of assessing cancer risk in healthy human populations, and the use of the technology should be made more attractive by developing automated performance steps and incorporating artificial intelligence methods into the scoring.