Whole Sets Of Chromosomes Research Articles

Pharmacogenomic biomarkers in coronary artery disease: a narrative review.

Coronary artery disease (CAD) has a high mortality rate. Despite various therapeutic targets, non-responsiveness to drugs remains a prevalent issue. Pharmacogenomics assesses the way an individual's genetic attributes affect their likely response to drug therapy. Single-nucleotide polymorphisms play a crucial role in determining these outcomes. This review offers an overview of single-nucleotide polymorphisms investigated in clinical studies and their associations with drug response/nonresponse in the treatment of CAD. A total of 104 studies of whole sets of chromosomes and several genes were explored. A total of161 polymorphisms exhibited associations with drug response/nonresponse in CAD across diverse ethnic populations. This pool can serve as a pharmacogenomic biomarker for predicting response to drug therapy in patients with CAD.

The role of gene dosage in budding yeast centrosome scaling and spontaneous diploidization.

Ploidy is the number of whole sets of chromosomes in a species. Ploidy is typically a stable cellular feature that is critical for survival. Polyploidization is a route recognized to increase gene dosage, improve fitness under stressful conditions and promote evolutionary diversity. However, the mechanism of regulation and maintenance of ploidy is not well characterized. Here, we examine the spontaneous diploidization associated with mutations in components of the Saccharomyces cerevisiae centrosome, known as the spindle pole body (SPB). Although SPB mutants are associated with defects in spindle formation, we show that two copies of the mutant in a haploid yeast favors diploidization in some cases, leading us to speculate that the increased gene dosage in diploids ‘rescues’ SPB duplication defects, allowing cells to successfully propagate with a stable diploid karyotype. This copy number-based rescue is linked to SPB scaling: certain SPB subcomplexes do not scale or only minimally scale with ploidy. We hypothesize that lesions in structures with incompatible allometries such as the centrosome may drive changes such as whole genome duplication, which have shaped the evolutionary landscape of many eukaryotes.

Artificial polyploidy induction for improvement of ornamental and medicinal plants

Green plants provide food, fuel, materials, and medicine for humans. Amongst these, medicinal plants contain unique molecules with therapeutic applications. However, our understanding of these organisms is in its infancy. Landscaping plants also have a great impact on the human soul and emotional perception. These two groups of plants are part of natural wealth and have great economic value. One of the remarkable breeding strategies to improve the valuable properties of plants is artificial polyploidy induction. Medicinal and ornamental plants with duplicated whole sets of chromosomes, although not always, have more distinctive characteristics such as modified phytochemical profile, higher content of desired pharma molecules, plant form, flower color, size and style, fragrance, vase life, and prolonged flowering period. Therefore, artificial chromosome doubling (ACD) of ornamental and medicinal plants could have significant economic consequences. In medicinal plants with an ornamental flower/inflorescence, and/or in ornamental plants bearing essential oils, ACD is a dual beneficial breeding strategy. Working with both in vitro and in vivo chromosome doubling pathways, researchers are able to produce custom-designed plants with higher marketability. Some critical factors must be considered to establish a successful ACD protocol. The plant genotype and explant type are important parameters in this procedure. Type, dosage and duration of application (exposure time) of antimitotic agent (AMA) should also be considered as the main factors. Antimitotic agents can be classified according to their efficacy and toxicity. Although colchicine is the most applied and well-known AMA, there are other alternative mitotic spindle inhibitors with higher specificity for tubulin binding sites in plant materials and possessing less toxicity for animal tubulin. Testing the interaction effects of plant and AMA parameters is necessary for establishing an ACD breeding program and promoting the economic values of medicinal and ornamental plants. This paper reviews significant developments in polyploidization using different antimitotic agents over the last decade in the field of ornamental and medicinal plants. Artificial polyploidy induction is one of the applicable breeding methods in ornamental and medicinal plants. Increasing the efficiency of chromosome doubling and fast-reliable screening of desired phenotypes are prerequisites for production of custom-designed medicinal and ornamental plants through artificial polyploidy induction.

Tracking down the molecular architecture of the synaptonemal complex by expansion microscopy

The synaptonemal complex (SC) is a meiosis-specific nuclear multiprotein complex that is essential for proper synapsis, recombination and segregation of homologous chromosomes. We combined structured illumination microscopy (SIM) with different expansion microscopy (ExM) protocols including U-ExM, proExM, and magnified analysis of the proteome (MAP) to investigate the molecular organization of the SC. Comparison with structural data obtained by single-molecule localization microscopy of unexpanded SCs allowed us to investigate ultrastructure preservation of expanded SCs. For image analysis, we developed an automatic image processing software that enabled unbiased comparison of structural properties pre- and post-expansion. Here, MAP-SIM provided the best results and enabled reliable three-color super-resolution microscopy of the SCs of a whole set of chromosomes in a spermatocyte with 20–30 nm spatial resolution. Our data demonstrate that post-expansion labeling by MAP-SIM improves immunolabeling efficiency and allowed us thus to unravel previously hidden details of the molecular organization of SCs.

Dipoid-Specific Genome Stability Genes of S. cerevisiae: Genomic Screen Reveals Haploidization as an Escape from Persisting DNA Rearrangement Stress

Maintaining a stable genome is one of the most important tasks of every living cell and the mechanisms ensuring it are similar in all of them. The events leading to changes in DNA sequence (mutations) in diploid cells occur one to two orders of magnitude more frequently than in haploid cells. The majority of those events lead to loss of heterozygosity at the mutagenesis marker, thus diploid-specific genome stability mechanisms can be anticipated. In a new global screen for spontaneous loss of function at heterozygous forward mutagenesis marker locus, employing three different mutagenesis markers, we selected genes whose deletion causes genetic instability in diploid Saccharomyces cerevisiae cells. We have found numerous genes connected with DNA replication and repair, remodeling of chromatin, cell cycle control, stress response, and in particular the structural maintenance of chromosome complexes. We have also identified 59 uncharacterized or dubious ORFs, which show the genome instability phenotype when deleted. For one of the strongest mutators revealed in our screen, ctf18Δ/ctf18Δ the genome instability manifests as a tendency to lose the whole set of chromosomes. We postulate that this phenomenon might diminish the devastating effects of DNA rearrangements, thereby increasing the cell's chances of surviving stressful conditions. We believe that numerous new genes implicated in genome maintenance, together with newly discovered phenomenon of ploidy reduction, will help revealing novel molecular processes involved in the genome stability of diploid cells. They also provide the clues in the quest for new therapeutic targets to cure human genome instability-related diseases.

Karyotyping of human oocytes by cenM-FISH, a new 24-colour centromere-specific technique

Metaphase II (MII) chromosome complements are difficult to karyotype. The objective of this study was to investigate the efficiency and limitations of centromere-specific multiplex fluorescence in situ hybridization (cenM-FISH), a new 24 colour FISH technique using centromere-specific probes, to analyse the whole chromosome complement within human oocytes. Oocytes were donated by 34 patients undergoing ovarian stimulation and IVF. The MII oocytes were analysed by means of cenM-FISH, while the confirmation of results was performed by FISH and/or by analysing the corresponding first polar bodies using comparative genomic hybridization (CGH). A total of 30 cells, corresponding to 16 oocytes and 14 first polar bodies, were successfully karyotyped by either cenM-FISH or CGH. The incidence of aneuploidy was 25%, and eight out of nine aneuploidy events were confirmed by CGH and FISH. We demonstrate here for the first time that the identification of any numerical abnormality in oocytes is feasible using cenM-FISH. Despite the fact that the fixation efficiency remains low, the present results confirm the advantage of analysing the whole set of chromosomes to make an accurate estimation of the aneuploidy rate in human oocytes.

Confined placental mosaicism and intrauterine fetal development

Chromosomal mosaicism is the presence of two or more cell lines with different chromosomal complements in an individual derived from a single zygote (which is distinguishable from chimaerism in which an individual is derived from more than one zygote). Mosaicism may involve a number of different karyotypic abnormalities including those for whole sets of chromosomes (polyploidy, including triploidy and tetraploidy), trisomies, sex chromosomal anomalies and chromosomal rearrangements. Mosaicism itself may be present in all the tissues of the body and placenta, or it may only be seen in certain tissues or may be restricted to only the placenta and extraembryonic membranes. The type of mosaicism seen depends upon the stage of development at which it originated, the tissue types to which the abnormal cell lines were distributed and the cell cycle times of both the normal and abnormal cells. The phenotypic effects or consequences of chromosomal mosaicism may be dramatic. During the pregnancy, high levels of mosaicism are seen in early abnormal preimplantation embryos, spontaneous abortions, intrauterine growth restriction and intrauterine fetal death. However, not all cases of mosaicism are serious and the presence of a normal cell line may dilute the effects of an abnormal cell line to such an extent that in many cases mosaicism will remain undetected because the consequences are not severe. Investigations of chromosomal mosaicism were, until recently, restricted to those cells which could be induced to divide and be karyotyped from metaphase analysis. Advances in molecular genetics and cytogenetics have made possible the identification of chromosomal abnormalities, specifically mosaicism in interphase cells. The identification of abnormalities such as confined placental mosaicism and its association with uniparental disomy has led to the recognition that chromosomal mosaicism plays a major role in abnormal human development and dysmorphology (Hall, 1990). An understanding of mosaicism and the role of the placenta during development, including the phenomenon of trisomic zygote rescue, is helping to cast light on problems in prenatal diagnosis, many of which involve confined placental mosaicism.

Cytological studies in some members of cyperaceae.

Cyperaceae is one of the large monocotyledonous families of cosmopolitan distribution comprising over 5000 species in 120 genera. Karyomorphology and meiosis in 19 species belonging to Ascopholis, Cyperus s. l. and Lipocarpha have been studied. Karyotypic analysis has been carried out for the first time in Ascopholis gamblei (2n=80), Cyperus tenuispica (2n=26), C. pilosus (2n=36, 68), C. diffusus (2n=38), C. pseudokyllingioides (2n=40), C. tenuiculmis (2n=44), C. rubicundus (2n=42, 50, 52), C. sanguinolentus (2n=50), C. corymbosus (2n=108), C. dubius (2n=112), C. cyperinus var. laxatus (2n=136), C. cyperinus var. pictus (2n=152), C, pangorei (2n=208), and Lipocarpha sphacelata (2n=38). The remaining species, C. haspan (2n=26), C. difformis (2n=36), C. distans (2n=58), C. procerus (2n=64), C. laevigatus (2n=88) and L. chinensis (2n=26), are studied because of discrepancies in the previous chromosome number reports. A deviation from the previous reports has been noticed in C. procerus and C. laevigatus, whereas the remaining taxa conform to one of the earlier reports. Ascopholis, a monotypic genus falls under the series having the basic number of x=5. Of the 16 species of Cyperus studied, 6 species conform to the basic number of x=8, 3 fit into the basic number of x=9 and one falls under the basic number of x=13. New basic numbers such as x=5, 11, 19 and 29 are suggested for remaining 6 species since they do not fit into any of the existing basic numbers known so far. Two species of Lipocarpha fall under the basic number of x=13 and 19. The karyotypes of all the species are found to be symmetrical with the predominance of chromosomes having median centromeres. In all the taxa investigated, the chromosomes have been found to have localized centromeres. Mixoploidy has been observed in C. pilosus and C. rubicundus. Structural changes including fragmentation and duplication of single or whole set of chromosomes are suggested to be responsible for bringing about the wide range of chromosome numbers in the taxa studied. The taxonomic implications of cytological findings are discussed.

THE KARYOTYPES OF DIPLOID CESPITOSE ZINNIAS: A METHOD AND ANALYSIS

The karyotypes of the three diploid (n = 10) species of the subg. Diplothrix (Zinnia—Compositae) were compared to determine whether there were any demonstrable differences which could then be sought in their polyploid derivatives. Because many of the chromosomes in a set were too similar to distinguish confidently between them, a method of analysis was developed which measures the similarity of whole sets of chromosomes rather than individual ones. The method consists of measuring the distances between graph‐plotted vertices representing arm lengths of chromosomes of real or paper hybrids and then comparing these distances by means of U tests with those similarly derived for the “parents.” This procedure obviates the need of attempting to identify morphologues (morphologically similar chromosomes) in a somatic diploid root‐tip cell and to equate corresponding pairs of chromosomes from different cells of a single plant or from different species or hybrids. No demonstrable differences in the karyotypes of diploid cespitose zinnias were found. Analysis of previously published data by this method indicated that there has been a general non‐objectivity and non‐operationalism in the determination of homologous chromosomes, and a general but unwarranted assumption that morphologues are in reality genologues (genetically corresponding chromosomes).

The Karyotypes of Diploid Cespitose Zinnias: A Method and Analysis

The karyotypes of the three diploid (n = 10) species of the subg. Diplothrix (Zinnia—Compositae) were compared to determine whether there were any demonstrable differences which could then be sought in their polyploid derivatives. Because many of the chromosomes in a set were too similar to distinguish confidently between them, a method of analysis was developed which measures the similarity of whole sets of chromosomes rather than individual ones. The method consists of measuring the distances between graph-plotted vertices representing arm lengths of chromosomes of real or paper hybrids and then comparing these distances by means of U tests with those similarly derived for the “parents.” This procedure obviates the need of attempting to identify morphologues (morphologically similar chromosomes) in a somatic diploid root-tip cell and to equate corresponding pairs of chromosomes from different cells of a single plant or from different species or hybrids. No demonstrable differences in the karyotypes of diploid cespitose zinnias were found. Analysis of previously published data by this method indicated that there has been a general non-objectivity and non-operationalism in the determination of homologous chromosomes, and a general but unwarranted assumption that morphologues are in reality genologues (genetically corresponding chromosomes).

A HAPLOID PLANT IN <i>PORTULACA GRANDIFLORA</i> HOOK

1. The gametic chromosome number in the normal Portulaca grandiflora is 9 as already stated by TJEBBES, and the somatic number is 18 (Fig. 18).2. Two haploids were found among 168 F2 interspecific-hybrids (Magenta No. 22×Orange No. 35) in 1931, next year one haploid was obtained from 100 F3 plants. Their parents were normal morphologically and cytologically. These haploids are of about half the stature of P. grandiflora with all organs proportionally smaller.3. There are 9 univalents in the first maturation division of P. M. C.. The 9 univalents are separate in the possible assortment of 1 and 8, 2 and 7, 3 and 6, 4 and 5 (Tab. 1). Sometimes 1-3 lagging chromosomes are observed (Figs. 2-5).4. In the homotypic division the halves of dyad chromosomes are distributed with the result that four nuclei are formed all lacking whole set of chromosomes. Accordingly the pollen grains, which are shrunken and empty, have no function (Figs. 6-10, Tab. 2). As far as the present investigation goes, I could not find the assortment of 0 and 9. This assortment is however possible in rare case.5. Haploid selfed gave no seed at all, and also pollination experiment with the haploid on normal plants was negative, but its reciprocal cross gave 5 seeds. One of them gave a progeny almost wholly of parent type, and has diploid chromosome number of P. grandiflora. This fact apparently indicates that the non-reduction of chromosomes happened in maturation division of E. M. C. of the haploid plant.