Chromosomal Polymorphism Research Articles

Adaptation of Drosophila subobscura chromosomal inversions to climatic variables: the Balkan natural population of Avala.

The adaptive value of chromosomal inversions continues raising relevant questions in evolutionary biology. In many species of the Drosophila genus, different inversions have been recognized to be related to thermal adaptation, but it is necessary to determine to which specific climatic variables the inversions are adaptive. With this aim, the behavior of thermal adapted inversions of Drosophila subobscura regarding climatic variables was studied in the natural population of Avala (Serbia) during the 2014-2017 period. The results obtained were compared with those previously reported in the Font Groga (Barcelona, Spain) population, which presents different climatic and environmental conditions. In both populations, it was observed that most thermal adapted inversions were significantly associated with the first, second or both principal components, which were related with maximum, minimum and mean temperatures. Moreover, a significant increase over years (2004-2017) for the minimum temperature was detected. In parallel, a significant variation over time in Avala was only observed for the frequencies of 'warm' and 'non-thermal' adapted inversions of the U chromosome. However, stability in the chromosomal inversion polymorphism was observed for the 2014-2017 period which might result from the temporal span of the study and/or selective process acting on the population.

Comparative Cytogenetic Analysis of Three Eumeninae Species (Hymenoptera, Vespidae)

Eumeninae represents the largest subfamily within Vespidae, with 3,600 species described. Of these, only 18 have been cytogenetically analysed. In the present study, we used both classical and molecular techniques to characterise and compare the karyotypes of 3 Eumeninae species, namely, Ancistrocerus sp., Pachodynerus grandis, and Pachodynerus nasidens. Ancistrocerus sp. presented a haploid chromosome number of n = 12, with the first 2 chromosomes of the karyotype being almost entirely heterochromatic and much larger than the remaining chromosomes. The 2 Pachodynerus species presented the same chromosome number (n = 11 and 2n = 22) but displayed different karyotypic formulae. Additionally, chromosomal polymorphisms were observed in the analysed P. nasidens female. In the 3 species, heterochromatin was located in one of the chromosome arms. Fluorochrome staining revealed a balanced composition of AT and GC bases within the chromatin for each of the 3 species, except for few regions that were visibly GC-rich. All species had a single 18S rDNA site that co-localised with GC-rich regions; however, this localisation varied from species to species and not all GC-rich regions corresponded to ribosomal genes. Based on the cytogenetic data obtained here, we discuss the possible numerical/structural rearrangements that may be involved in the karyotypic evolution of the 3 studied species. In addition to the first description of the molecular cytogenetic characteristics of the Eumeninae subfamily and the genus Pachodynerus, this study also provides a relevant contribution towards the discussion of chromosomal evolution in Eumeninae wasps.

Peculiarities of karyotype of the Ukrainian aboriginal Hutsul breed of horse

Saving biodiversity and assessment of the genetic diversity of local breeds of domestic animals as priority subjects of protection in agrobiocenoses is one of the global challenges facing humanity in the 21st century. Hutsul horse is one of the oldest horse breeds in Ukraine, which according to the gene pool subject of horses in Ukraine belongs to the group “Local (mountain and ponies)” of the I category, which is already on the verge of extinction, and according to the FAO classification it is considered to be a subject of the gene pool threatened with extinction. Since the breeding chromosomal polymorphism of horses is insufficiently studied, it is timely to carry out a cytogenetic analysis of the characteristics of spontaneous mutagenesis in Hutsul horses. Karyotypic variability of Hutsul breed horses was determined using the methods of cytogenetic analysis and micronucleus test. The paper presents the results of cytogenetic analysis and micronucleus test of karyotypic variability of Hutsul breed horses. Asynchronous divergence of centromere regions of chromosomes occurs as a result of premature replication of centromere regions of heterochromatin associated with centromere activity. In the studied Hutsul horses, the magnitude of this variability corresponds to the spontaneous level for horses as a whole (2.2-9.1 %). No structural chromosomal abnormalities (chromosomal breaks) were revealed in Hutsul breed horses at Krai Neba LLC, and in the animals of the Hutsulshchina National Nature Park, the percentage of metaphase plates with chromosomal breaks was low (1.1 %), which indicates the stability of the karyotype of the studied animals. The results of the micronucleus test showed that the proportion of lymphocytes with micronuclei in the animals at the both farms was practically the same - 4.0-4.2. It can be concluded based on the data obtained that the animals under study were in ecologically clean conditions relative to the level of radionuclide contamination and were characterized by karyotype stability and reduced sensitivity to mutagenic factors of various nature.

Extreme Y chromosome polymorphism corresponds to five male reproductive morphs of a freshwater fish.

Loss of recombination between sex chromosomes often depletes Y chromosomes of functional content and genetic variation, which might limit their potential to generate adaptive diversity. Males of the freshwater fish Poecilia parae occur as one of five discrete morphs, all of which shoal together in natural populations where morph frequency has been stable for over 50 years. Each morph uses a different complex reproductive strategy and morphs differ dramatically in colour, body size and mating behaviour. Morph phenotype is passed perfectly from father to son, indicating there are five Y haplotypes segregating in the species, which encode the complex male morph characteristics. Here, we examine Y diversity in natural populations of P. parae. Using linked-read sequencing on multiple P. parae females and males of all five morphs, we find that the genetic architecture of the male morphs evolved on the Y chromosome after recombination suppression had occurred with the X. Comparing Y chromosomes between each of the morphs, we show that, although the Ys of the three minor morphs that differ in colour are highly similar, there are substantial amounts of unique genetic material and divergence between the Ys of the three major morphs that differ in reproductive strategy, body size and mating behaviour. Altogether, our results suggest that the Y chromosome is able to overcome the constraints of recombination loss to generate extreme diversity, resulting in five discrete Y chromosomes that control complex reproductive strategies.

Employing Alu Elements to Detect Chromosomal Inversions

Background and Objective Chromosomal inversion polymorphism events occur when a segment of DNA is flipped relative to its ancestral origin. They are frequent phenomena seen in the genomic evolution of related species and the initiation of cancer progression, and improved ability to detect such chromosomal inversion events would aid in evolutionary and oncological research. As balanced rearrangements, inversion polymorphisms remain difficult for traditional low-cost techniques to detect. Methods Here, the authors propose a novel methodology for detecting inversions by recording and analyzing the genetic loci of orthologous Alu sequences between any two given primate species. Alu insertion polymorphism events have long been used as a technique to identify evolutionary inversions, but their relative rarity limits identification of low- or medium-resolution inversions. However, the following methodology has largely eliminated this disadvantage by utilizing all Alu elements within the genome, and not exclusively insertion events. First, Alu elements from 31 subfamilies in the Chimpanzee (Pan troglodytes) and Gorilla (Gorilla gorilla) genomes (panTro4 and gorGor4, respectively) were extracted from the University of California Santa Cruz's Genome Table Browser (UCSC's GTB). For each Alu sequence in panTro4, Smith-Waterman string distances were calculated between that Alu sequence and every other Alu sequence in gorGor4 within its subfamily. This allowed the identification of orthologous, conserved Alu sequences between species, as well as each sequence pairings’ respective chromosome number and specific location. Orthologous chromosomes were then determined by the chromosomes containing the relatively highest number of orthologous sequences. Finally, inversions were mapped between those respective chromosomes and accompanied by graphical representations. Results Our methodology along with its produced graphical comparisons of primate species allowed for clear detection of patterns displaying inversions, which were then validated by previously published genomic differences between members of the primate Order. As a test case, the known inversion between chimpanzee and gorilla chromosome 7 was examined, which was both individually detected using 27 of the total 31 subfamilies and was definitively detected using the combination of all subfamilies (nearly 3,500 loci of ~300 base pairs each). For further validation, a list of all known inversions predicted from UCSC's GTB greater than 5 Mbp between the panTro4 and gorGor4 genomes was compiled. After comparison against each of these 10 predictions, 9 were detected with high confidence. Conclusion Such a high degree of accuracy with accepted findings demonstrates the validity of the novel Alu-based strategy in detecting inversion events within primate genomes. This methodology may have numerous practical applications in genomic comparisons of related species and identification of clinically relevant inversions. Further work must be done to confirm its efficacy in detecting such inversions among other species of the primate order and to resolve the minimum amount of computational comparison required in order to consistently and accurately identify inversion events.

Performance of Chromosomal Microarray Analysis for Detection of Copy Number Variations in Fetal Echogenic Bowel.

BackgroundFetal echogenic bowel (FEB) is associated with an increased risk of poor pregnant outcomes; however, karyotyping fails to detect copy number variations (CNVs) in FEB. This study aimed to evaluate the performance of chromosomal microarray analysis (CMA) for detection of FEB.MethodsThe medical records of 147 pregnant women with FEB recruited during December 2015 to December 2018 were retrospectively reviewed, and prenatal samples were collected for karyotyping and CMA. The detection of chromosomal abnormality was compared between karyotyping and CMA.ResultsKaryotyping identified eight cases with abnormal karyotypes (5.44% prevalence), including four fetuses with pathogenic aneuploidy, three with chromosome polymorphism and one with balanced chromosome translocation. CMA identified 13 abnormal CNVs (8.84% prevalence), including 4 fetuses with pathogenic aneuploidy as detected by karyotyping and 9 additional CNVs with normal karyotypes; however, CMA failed to detect chromosome polymorphism and balanced chromosome translocation. In fetuses with isolated FEB, no cases presented pathogenic findings and CMA detected two cases with variants of uncertain significance (VOUS). In cases presenting FEB along with other ultrasound abnormalities, CMA detected three cases with pathogenic CNVs and four cases with VOUS in addition to four cases with aneuploidy. There was no significant difference in the detection of abnormal CNVs between the fetuses with echogenic bowel alone and along with other ultrasound abnormalities (10% vs 8.67%, P > 0.05). Except 9 fetuses lost to the follow-up, the other 138 fetuses with echogenic bowel were successfully followed up. Pregnancy was terminated in 5 fetuses with chromosomal abnormality, 2 with pathogenic CNVs and 1 with VOUS, and other 16 with normal karyotypes and CMA findings but showing ultrasound abnormalities or multiple malformations.ConclusionIsolated FEB is associated with a good prognosis, and a satisfactory pregnant outcome is expected for fetuses with echogenic bowel that are negative for chromosomal anomalies and other severe structure abnormalities. CMA shows an important value in the genetic diagnosis of FEB. As a supplement to karyotyping, CMA may improve the accuracy of prenatal diagnosis of fetal intestinal malformations in pregnant women with FEB.

Predominant wheat-alien chromosome translocations in newly developed wheat of China.

The online version contains supplementary material available at 10.1007/s11032-021-01206-3.

RADSex: A computational workflow to study sex determination using restriction site-associated DNA sequencing data.

The study of sex determination and sex chromosome organization in nonmodel species has long been technically challenging, but new sequencing methodologies now enable precise and high-throughput identification of sex-specific genomic sequences. In particular, restriction site-associated DNA sequencing (RAD-Seq) is being extensively applied to explore sex determination systems in many plant and animal species. However, software specifically designed to search for and visualize sex-biased markers using RAD-Seq data is lacking. Here, we present RADSex, a computational analysis workflow designed to study the genetic basis of sex determination using RAD-Seq data. RADSex is simple to use, requires few computational resources, makes no prior assumptions about the type of sex-determination system or structure of the sex locus, and offers convenient visualization through a dedicated R package. To demonstrate the functionality of RADSex, we re-analysed a published data set of Japanese medaka, Oryzias latipes, where we uncovered a previously unknown Y chromosome polymorphism. We then used RADSex to analyse new RAD-Seq data sets from 15 fish species spanning multiple taxonomic orders. We identified the sex determination system and sex-specific markers in six of these species, five of which had no known sex-markers prior to this study. We show that RADSex greatly facilitates the study of sex determination systems in nonmodel species thanks to its speed of analyses, low resource usage, ease of application and visualization options. Furthermore, our analysis of new data sets from 15 species provides new insights on sex determination in fish.

Sources of Chromosomal Polymorphism of Microsporocytes in Species of Lilium L. and Allium L.: Cytomixis, Extra Chromosomes, and Chromatin Diminution

Cytomixis and chromosomal polymorphism of microsporocytes in microsporogenesis of the species Lilium croceum Chaix, Allium fistulosum L., and A. cepa L. were studied. It was found that the main cytomictic events are associated with the early prophase of meiosis and are obligatory (constitutive) for the examined species. In metaphase microsporocytes, the so-called extra chromosomes, presumably of cytomictic origin, were identified. They are characterized by weakening of synapsis and/or disintegration of homologues and associations with bivalents of the basic karyotype with the formation of secondary associations of chromosomes. Extra chromosomes are present not only in hyperchromosomal but also in eu- and hypochromosomal microsporocytes. The majority of extra chromosomes seem to be a “genetic ballast” for the cell, which it gets rid of using a wide range of cellular tools, in particular, chromosomal rearrangements, chromatin diminution, asymmetry of division, cytomixis, and programmed cell death. Nevertheless, some extra chromosomes can participate in the rearrangement of the karyotype of microsporocytes and microspores.

Association of 3 single nucleotide polymorphisms of the eighth chromosome with remodeling of the myocardium and carotid arteries in the Kazakh population.

Cardiovascular diseases are one of the key health issues in Kazakhstan. According to the WHO, the prevalence of arterial hypertension (AH) was 28% in males and 25% in females in 2015, which puts up vastly to premature mortality from non-communicable diseases.The search for genetic features of target organ lesions processes in AH is relevant. The goal of this study was to search for the genetic markers of myocardial remodeling (MR) and carotid artery remodeling (CAR).A total of 866 hypertensive individuals were recruited in Nur-Sultan, Kazakhstan. Their blood was genotyped for 9 single nucleotide polymorphisms (SNPs) of the eighth chromosome to find an association with remodeling. The analysis was carried out in the group pairs (control and CAR, control and MR, and control and CAR and MR). The genotype–phenotype association was assessed using 5 different inheritance models: dominant, codominant, recessive, overdominant, and log-additive.Statistically significant results were found for 3 SNPs (rs2407103, rs11775334, rs2071518) which minor alleles enlarged risks of MR and CAR in AH in the studied population. Three polymorphisms have previously been associated with АН and some other traits like pulse pressure and blood glucose in other ethnic populations: rs2407103 – in Afro-American population, rs11775334 – in the European population, rs2071518 is well studied in various ethnic populations (European, South Asian, Afro-American, Hispanic, East Asian).

Y chromosome analysis for common surnames in the Japanese male population.

For many years of Japan's long history, Japanese surnames have been handed down patrilineally. This study investigated relations between major surnames and Y chromosomal polymorphism among the Japanese male population. To analyze genetic phylogeny in namesakes, the Y-single nucleotide polymorphism (SNP) plus Y-short tandem repeat (STR) approach was employed. A haplogroup based on SNPs and haplotypes at 17 STR loci were typed in 567 unrelated volunteers recruited in Kanagawa, Japan. Samples covered 27 common surnames such as Satoh and Suzuki, each name having 10-55 bearers. Significant difference was found for SNP haplogroup compositions and a multidimensional scaling plot using STR haplotypes in several surname groups. By contrast, these common surnames displayed wide diversity with phylogenetic networks, suggesting that no genetic drift event has occurred in their history. In all, 22 descent clusters were found, as judgcriteria ed by ad hoc of groups within five mutational steps in the 15 STR loci with the same haplogroup. The times of the most recent common ancestor ranged from 279 to over 2577 years. According to the approximate millennium span of Japanese surname history, descent criteria are expected to be reasonable for grouping within four step-neighbors. High heterogeneity of common surnames resembles that observed for England and Spain, but not for Ireland. Our results highlight that common Japanese surnames consist of descent clusters and many singletons, reflecting a mixture of long-term bearers and short-term bearers among the population. The genetic study of this population revealed characteristic features of Japanese surnames.

Chromosomal Polymorphism and Speciation: The Case of the Genus Mazama (Cetartiodactyla; Cervidae).

Chromosomal polymorphism plays a major role in speciation processes in mammals with high rates of karyotypic evolution, as observed in the family Cervidae. One remarkable example is the genus Mazama that comprises wide inter- and intra-specific chromosomal variability. To evaluate the impact of chromosomal polymorphisms as reproductive barriers within the genus Mazama, inter-specific hybrids between Mazama gouazoubira and Mazama nemorivaga (MGO × MNE) and intra-specific hybrids between cytotypes of Mazama americana (MAM) differing by a tandem (TF) or centric fusion (Robertsonian translocations—RT) were evaluated. MGO × MNE hybrid fertility was evaluated by the seminal quality and testicular histology. MAM hybrids estimation of the meiotic segregation products was performed by sperm-FISH analysis. MGO × MNE hybrids analyses showed different degrees of fertility reduction, from severe subfertility to complete sterility. Regarding MAM, RT, and TF carriers showed a mean value for alternate segregation rate of 97.74%, and 67.23%, and adjacent segregation rate of 1.80%, and 29.07%, respectively. Our results suggested an efficient post-zygotic barrier represented by severe fertility reduction for MGO × MNE and MAM with heterozygous TF. Nevertheless, RT did not show a severe effect on the reproductive fitness in MAM. Our data support the validity of MGO and MNE as different species and reveals cryptic species within MAM.

Evaluation of Chromosomal Structural Anomalies in Fertility Disorders.

Background and objectives: Reproductive disorders may occur not only due to environmental factors (air pollution, stressful lifestyle, previous abortions or the use of contraceptives) but also due to genetic factors. Materials and Methods: The aim of the study was to identify the range and frequency of chromosomal aberrations in couples (n = 99) with infertility or recurrent miscarriages in Lithuania. The data were collected from the out-patient medical histories. The couples were divided into three groups based on pregnancy, childbirth and the number of miscarriages. The Chi-square test was used to carry out the statistical analysis, and the statistical significance was (p < 0.05). Results: There were 6.6% (n = 13) structural changes observed in the karyotype tests. Chromosomal aberrations were found in 3% (n = 6) of the subjects, while 3.6% (n = 7) of them had chromosomal length polymorphisms. No difference was found between the aberration frequency in the karyotypes of men and women (p > 0.05). The most common aberrations were balanced translocations (23.1%, n = 3) which accounted for 15.4% of the reciprocal (n = 2) and 7.7% of the Robertsonian type (n = 1) of translocations. The most frequent aberrations were found in couples with the inability to conceive (42.9% (n = 3), p = 0.031). The childless couples and those with recurrent miscarriages showed an aberration rate of 8.2% (n = 5), while in the couples with at least one child it was 16.1% (n = 5). The group of couples unable to conceive had a significantly higher aberration rate of 28.6% (n = 2), p = 0.029. Miscarriages in partners’ families accounted for 8.1%. Miscarriages on the female side of the family accounted for 4.5% (n = 9), on the male side it accounted for 2.5% (n = 5) and on both sides it accounted for 1.1% (n = 2). There were no statistically significant differences observed between the female and male sides (p > 0.05). The miscarriages observed in the second group of couples (childless with ≥2 miscarriages) were more frequent at 18.1% (n = 11), in the third group (having children ≥2 miscarriages) they were less frequent at 12.9% (n = 4), while no miscarriages were recorded in the first group of infertile couples. In total, 3% of the identified significant chromosomal aberrations were likely to trigger miscarriages or the inability to conceive. Conclusions: In couples with reproductive disorders, chromosomal mutations and chromosomal length polymorphisms were found at similar rates: 3% vs. 3.6%. The highest aberration rate was found in couples that were unable to conceive, a lower one was found in a group with children and ≥2 miscarriages, and the lowest one was found in a childless group of subjects with ≥2 miscarriages. The miscarriage rate in partner families was 8.1%; however, no difference was found between the male and female sides.

Chromosome Polymorphism and Human Pathology: About 27 Cases of Chromosome 9 Inversion in the Beninese Population

The chromosomal polymorphism defined by variations of some chromosomal regions of a person (the constitutive heterochromatin and the short arms of the acrocentric chromosomes (13 to 15 and 21 - 22)) sometimes highlighted problems with regard to their safety and their pathogenicity. Polymorphisms are usually found in the same family and transmitted in the dominant Mendelian. Chromosome 9 inversion is a frequent phenomenon that some cytogeneticists consider as a variant of normal. Despite its classification as a minor chromosome rearrangement which does not correspond to abnormal phenotypes, many reports have raised conflicting opinions as well, and its complete safety is controversial. 27 cases of inversion of chromosome 9 were identified in our laboratory. The main indications for karyotype of the case of inv (9) were congenital cardiopathy (18.5%), sex development disorders of (18.5%), down syndrome (18.5%), and infertility (14.8%). This study stood out the observations of many authors who highlighted the involvement of inv (9) in the genesis of several pathologies.

A Case-Control Study Identifying the Frequency and Spectrum of Chromosomal Anomalies and Variants in a Cohort of 1000 Couples with a Known History of Recurrent Pregnancy Loss in the Eastern Region of India.

Background:Recurrent pregnancy loss (RPL) is a common occurrence that affects up to 15% of couples in their reproductive years. In both males and females with RPL and infertility, chromosomal abnormalities play a significant impact.Aim:The study was designed to examine the involvement of chromosomal anomalies and the frequency of certain chromosomal variants persistent among couples experiencing RPL.Setting and Design:This case–control study was conducted on 1000 couples from January 2015 to September 2020 in the state of Odisha, India, strictly adhering to principles of Helsinki Declaration (1975). The study was performed at the School of Biotechnology, KIIT University in collaboration with inDNA Life Sciences Private Limited.Materials and Methods:A cohort of 1148 individuals with a history of RPL were selected for the study and they were screened with respect to fertile controls for the presence of any chromosomal anomaly using G-banding, nucleolar organizing region (NOR)-banding and fluorescence in situ hybridisation wherever necessary.Statistical Analysis:The connection between distinct polymorphic variations and the occurrence of RPL was assessed using Fisher's exact test. Significant was defined as a P ≤ 0.005.Results:One hundred and thirty-four individuals were found to harbor chromosomal anomalies. This study elucidates that along with balanced chromosomal translocations, the involvement of polymorphic variants also plays a significant role in cases of RPL.Conclusion:The cumulative occurrence of chromosomal anomalies and variants across our cohort of 1148 individuals indicates that the chromosomal assessment of all couples experiencing RPL must be performed by all the clinicians. This study aids us in identifying chromosomal polymorphisms as major players of RPL in addition to novel chromosomal translocations.

Geographic distribution of sex chromosome polymorphism in Anastrepha fraterculus sp. 1 from Argentina

BackgroundAnastrepha fraterculus is recognized as a quarantine pest in several American countries. This fruit fly species is native to the American continent and distributed throughout tropical and subtropical regions. It has been reported as a complex of cryptic species, and at least eight morphotypes have been described. Only one entity of this complex, formerly named Anastrepha fraterculus sp. 1, is present in Argentina. Previous cytogenetic studies on this morphotype described the presence of sex chromosome variation identified by chromosomal size and staining patterns. In this work, we expanded the cytological study of this morphotype by analyzing laboratory strains and wild populations to provide information about the frequency and geographic distribution of these sex chromosome variants. We analyzed the mitotic metaphases of individuals from four laboratory strains and five wild populations from the main fruit-producing areas of Argentina, including the northwest (Tucumán and La Rioja), northeast (Entre Ríos and Misiones), and center (Buenos Aires) of the country.ResultsIn wild samples, we observed a high frequency of X1X1 (0.94) and X1Y5 (0.93) karyomorphs, whereas X1X2 and X1Y6 were exclusively found at a low frequency in Buenos Aires (0.07 and 0.13, respectively), Entre Ríos (0.16 and 0.14, respectively) and Tucumán (0.03 and 0.04, respectively). X2X2 and X2Y5 karyomorphs were not found in wild populations but were detected at a low frequency in laboratory strains. In fact, karyomorph frequencies differed between wild populations and laboratory strains. No significant differences among A. fraterculus wild populations were evidenced in either karyotypic or chromosomal frequencies. However, a significant correlation was observed between Y5 chromosomal frequency and latitude.ConclusionsWe discuss the importance of cytogenetics to understand the possible route of invasion and dispersion of this pest in Argentina and the evolutionary forces acting under laboratory conditions, possibly driving changes in the chromosomal frequencies. Our findings provide deep and integral genetic knowledge of this species, which has become of relevance to the characterization and selection of valuable A. fraterculus sp. 1 strains for mass rearing production and SIT implementation.

The Influence of Chromosomal Polymorphism on Embryo Development and Embryonic Molecular Karyotype in Preimplantation Genetic Testing for Chromosomal Translocation.

Traditionally, chromosomal polymorphisms (CPMs) are normal genetic variants in individuals with no phenotypic variations. However, some studies have shown that CPM is related to reproductive diseases. We explored the influence of CPM on embryonic development and molecular karyotype in chromosomal translocation (CT) patients undergoing preimplantation genetic testing (PGT) between February 2013 and May 2019. Twenty-six cases with CPM and 56 controls with normal chromosomes were included. Furthermore, a 1:4 match pair analysis by female age included 39 cases with CTCPM and 185 controls with CT. There was no statistical difference in fertilization rate (78.48% vs. 78.33%), cleavage rate on Day 3 (90.32% vs. 89.16%), blastocyst rate (60.00% vs. 60.80%), and the high-quality blastocyst rate (36.31% vs. 35.22%) between CPM and normal chromosomes. The high-quality blastocyst rate of CTCPM was significantly lower than that for CT (26.78% vs. 38.89%). Moreover, there was no statistical difference in fertilization rate (70.65% vs. 70.37%), cleavage rate on Day 3 (88.67% vs. 89.53%), and blastocyst rate (48.48% vs. 53.17%) between CTCPM and CT. In addition, one CTCPM spouse had a lower high-quality blastocyst rate, especially of males with CTCPM. Abnormal embryo rates of CTCPM were significantly higher than those for CT (78.64% vs. 68.93%). Abnormal embryo rates were higher in both CTCPM and CPM paternal carriers with CT partners, respectively. For CT, CTCPM may have an impact on the high-quality blastocyst rate and embryonic molecular karyotype, especially in male patients. Patients with CTCPM are relatively rare, but this population would benefit from being explored using a larger sample size.

A review on the cytogenetics of the tribe Oryzomyini (Rodentia: Cricetidae: Sigmodontinae), with the description of new karyotypes.

Oryzomyini represents the most diverse and speciose tribe of subfamily Sigmodontinae, with 29 genera and about 141 species. This great diversity of species is distributed from southeastern North to southern South America. Its systematics have passed through major changes in the last years due to the integration of molecular data with morphological characters in phylogenetic inferences. Unsurprisingly, cytogenetic studies on Oryzomyini reflect such diversity, with chromosome diploid number varying from 2n = 16 to 2n = 88. In addition, some species present autosomal and sex chromosome polymorphisms, besides the presence of B chromosomes. However, despite decades of cytogenetic studies, our knowledge about the karyotype variability in this group were still poorly known. Considering such deep and profound changes on the tribe, along with important new evidence that was continuously being produced associated to field work in several areas of Brazil and South America, we performed a cytogenetic review of the Oryzomyini group. We provide standardized descriptions summarizing all the knowledge associated to the known species of the tribe. We also describe seven new karyotypes for the tribe, Euryoryzomys sp., 2n = 58 and FN = 92; Neacomys sp. 1, 2n = 48 and FN = 54; Neacomys sp. 2, 2n = 54 and FN = 62; Oecomys sp. 1, 2n = 54 and FN = 84; Oecomys sp. 2, 2n = 64 and FN = 92; Oecomys sp. 3, 2n = 84 and FN = 110; and Scolomys sp., 2n = 62 and FN = 80.

Frequency and clinical manifestation of prenatal cytogenetic diagnosis of chromosomal polymorphisms in Northeast China

ObjectiveTo retrospectively analyze the incidence of chromosomal polymorphisms in prenatal cytogenetic diagnostic cases and the effect of the clinical manifestation of these fetuses. Materials and methods490 fetuses with chromosomal polymorphisms among 9996 pregnant women who underwent prenatal cytogenetic diagnosis were included in this study and were set as group 1. Other 500 pregnant women, whose fetuses were with normal karyotypes, were randomly selected from the remaining pregnant women and set as group 2. Clinical information and outcomes and maternal serum screening results of group 1 were compared with group 2. ResultsThe frequency of fetal chromosomal polymorphism was 4.90% (490/9996). The most common variants observed were 1/9/16 qh± (2.27%, 227/9996), followed by inv(9) (0.90%, 90/9996). 94.62% (264/279) of fetal chromosomal variants were inherited from parents. No statistical difference was found in clinical information and outcomes and maternal serum screening results between group 1 and group 2. ConclusionThe fetus with chromosomal polymorphism has no impact on serum markers of second trimester screening and does not play an important role for the clinical outcome of the current pregnancy either, whether it is inherited from the parents or a de novo mutation.

Cytogenetic investigation of Arctic char \xd7 brook trout F1, F2 and backcross hybrids revealed remnants of the chromosomal rearrangements

Arctic char (Salvelinus alpinus) and brook trout (Salvelinus fontinalis) hybridize and their offspring is viable and fertile. This may be a real treat for the native European stocks of Arctic char which gene pools might be unintendedly contaminated with the genetic elements of brook trout. On the other hand, hybrids of these two species are appreciated by customers and have some potential for the aquaculture. Moreover, Salvelinus hybrids and backcross individuals are interesting models in the research focused on influence of hybridization on the genomic organization and chromosome rearrangements. Thus, the main goal of the present study was to examine chromosomes of Arctic char × brook trout F1, F2 hybrids and backcross individuals and compare with genomic information concerning parental species to recognize karyotypic changes provoked by the hybridization events. Application of conventional and molecular (FISH) techniques allow to identify characteristic chromosomes for both parental species in the hybrid progeny and show multiplicity of cytotypes among different types of crosses with variability in structure and number of chromosome (81–85) and chromosome arm (99–101). Chromosome fragment was detected in the karyotype of one F1 and one backcross individual and the presence of one triploid (3n) fish was documented. Occurrence of chromosomes containing internally located telomeric sequences (ITS) inherited after brook trout or both parental species was shown in F1 and backcross progeny. Moreover, additional CMA3-positive signal on chromosome from Arctic char pair no. 2 in F1 fish and interstitially located active NOR visible on subtelo-acrocentric (F2 hybrid) and acrocentric (Sf × H individual) chromosomes were detected. Described polymorphic chromosomes together with specific, interstitial location of CMA3-positive found in F2 and Sf × H hybrids and DAPI-positive regions observed in H × Sa fish at different uniarmed chromosomes pair presumably are remnants of chromosomal rearrangements. Provided results strongly indicate that the hybridization process influenced the genome organization in the Salvelinus hybrid progeny.