Diploid Chromosome Complement Research Articles

Revision of chromosome complement of an oriental bug Macrocheraia grandis (Gray, 1832) (Heteroptera: Pyrrhocoroidea: Largidae)

ABSTRACT Cytogenetic data of Macrocheraia grandis (Gray, 1832) have been a subject of much controversy as different diploid chromosome complements have been reported by different workers. In contrast to earlier studies claiming X0 and X1X20 sex mechanism in males, our observations suggest the existence of multiple X and Y chromosomes. On the basis of an exhaustive study of 457 well spread different stages, examination of the entire male meiotic cycle up to telophase II and study of the spermatogonial and oogonial complement we decided the chromosome complement to be 2n (male) = 12A+2m+XmYn, with m+n = 3, 5 or 7 and 2n (female) = 12A+2m+XmXn with m+n = 2, 3, 6 or 8 where m and n are the number of maternal and paternal sex chromosomes. Our data are further supplemented with banding techniques. Besides, the presence of a conspicuous autosomal bivalent, DAPI bright microchromosomes and presence of remnant nucleolar bodies up to diplotene are worth mentioning features of the species.

Mitotic metaphase karyotype of the mosquito Anopheles arabiensis Patton (Diptera: Culicidae) from Kassala State, eastern Sudan

The mosquito Anopheles arabiensis Patton is the most important malaria vector in Sudan. The study was conducted for the first time to describe numerically the karyotype of An. arabiensis from Kassala State, eastern Sudan. Adults An. arabiensis were caught from human dwellings during the rainy season of 2022. We examined for the first time the utility of brain ganglia tissues of adult mosquitoes for mitotic chromosomal preparations using Giemsa stain - spreading technique. High-quality chromosomal preparations were examined and photographed. Chromosome measurements were carried out using computer software and analyzed statistically using SPSS® software. The diploid mitotic chromosome complement of An. arabiensis consists of three pairs of chromosomes, two pairs of metacentric autosomes (chromosome II and chromosome III) and one acrocentric dot-shaped pair, sex chromosome, which is homomorphic in females (XX) and heteromorphic in males (XY). Chromosome II was described as the longest (2.61±0.07) of the complement and constitute 44.39% of the total length (5.88 μm) of the haploid chromosomes set, while chromosome I (X=1.39 ±0.04; Y=1.04±0.04) as the shortest chromosome. Chromosome X appears in the males significantly larger than chromosome Y (P = 0.00). Chromosome III has an intermediate length (1.88±0.06) compared with the other chromosomes. Comparison of the average lengths of the three chromosome pairs by ANOVA test revealed highly statistical significant differences between them (P < 0.00). The study establishes a strong cytogentic data, which can contribute to accurate identification of the mosquito An. arabiensis and to planning human malaria vector control programs in Kassala State, eastern Sudan.

A Comparative Study of the Karyomorphology of Grass Carp, <I>Ctenophaydon Idella</I> (Val.), Silver C P , <I>Hypophthalmichthys moliytic</I> (Val.) And Their F<sub>1</sub> Hybrid

A comparative study was carried out on the karyomorphology of the grass carp, Ctenopharyngodon idella (Val.) , silver carp, Hypophthalmichthys molitrix (Val.) and their F1 hybrid. An attempt has been made to tentat ively classify the karyotype of tne F1 hybrid on the basis of arm ratio and external morpoloy.
 The diploid chromosome complements (2n) in grass carp, silver carp and the hybrid were found to be 48 each. The karyotype of grass carp was observed to comprise metacentric (15 pairs) and submetacentric (9 pairs) types while that of silver carp consisted 6-metacentric, 6-submetacentric and 2-subtelocentric pairs. The F1 hybrid karyotype was observed to consist 16-metacentric, 30-submetacentric and 2-subtelocentric chromosomes in total.

Rebuilding the Cytogenetics of Atelognathus (Anura: Batrachylidae): Half a Century of Confusion

The genus Atelognathus is composed of five species that occur in the southernmost regions of Argentina and Chile. It belongs to the Batrachylidae, one of the few endemic anuran families from Patagonia. More than 50 yr ago, it was concluded that A. reverberii had a diploid chromosomal complement of 2N = 26, a feature later reported for other congenerics. In this work, we describe the cytogenetics of all known species of Atelognathus (A. nitoi, A. patagonicus, A. praebasalticus, A. reverberii, and A. solitarius) and two additional undetermined populations. Unexpectedly, our analyses showed that all have a diploid chromosomal complement 2N = 24, which contrasts with conclusions of previous studies. We conclude that a karyotype of 2N = 24 is shared in Atelognathus as a derived condition within Batrachylidae. Additionally, we describe and discuss other cytogenetics characters (i.e., nucleolar organizer region location and C-banding patterns) of Atelognathus and related genera of Batrachylidae in an evolutionary framework.

Frequency of Chromosomal Aberrations in Somatic Cells of Ukrainian Buffaloes (Bubalus bubalis L.)

Routine, GTG-, and Ag-staining techniques for the metaphase chromosome analysis were used to determine the spontaneous frequency of chromosomal aberrations and the level of chromosomal variability in the blood lymphocytes of Ukrainian buffaloes (Bubalus bubalis L.). It has been established that the diploid complement of chromosomes within the studied population of animals consists of 50 chromosomes (2n = 50, XX; 2n = 50, XY). Individual chromosomal variability was detected in some animals in the form of cells with aneuploidy and polyploidy sets of chromosomes as well as in the form of structural aberrations in autosomes. In particular, the chromosomal analysis based on differential staining technique has shown a duplicate in one chromosome of the second pair in individual females as well as an X monosomia and a chimerism over sex chromosomes. The total spontaneous level of chromosomal instability in the peripheral blood lymphocytes reached, on average, 14.35 ± 2.03% due to abnormalities of chromosomal and chromatid types. The Ag staining method was used to detect active NORs in six chromosome pairs (3p, 4p, 6q, 21q, 23q, and 24q).

The invasive alien freshwater flatworm Girardia tigrina (Girard, 1850) (Platyhelminthes, Tricladida) in Western Europe: new insights into its morphology, karyology and reproductive biology

Invasions of alien species form one of the major threats to global biodiversity. Among planarian flatworms many species are known to be invasive, in several cases strongly affecting local ecosystems. Therefore, a detailed knowledge on the biology of an invasive species is of utmost importance for understanding the process of invasion, the cause of its success, and the subsequent ecological impact on native species. This paper provides new information on the biology of introduced populations of the freshwater flatworm Girardia tigrina (Girard, 1850) from Europe. This species is a native of the Nearctic Region that was accidentally introduced into Europe in the 1920s. Since then, numerous records across the European continent bear witness of the invasiveness of this species, although only a few studies focused on the biology of the introduced populations. We report on the morphology of sexualized individuals from a fissiparous Italian population, representing the second record of spontaneous sexualization of fissiparous individuals in this species. A detailed morphological account of the reproductive apparatus of these ex-fissiparous animals is presented. Our results increased the number of morphological groups previously recognized for European populations of G. tigrina, thus corroborating the hypothesis on multiple independent introductions to this continent. Karyological results obtained from our fissiparous Italian individuals revealed a constant diploid chromosome complement of sixteen chromosomes. Further, we document the marked intraspecific variation in several morphological features of this species.

Cytological Variability in Artemisia L. inhabiting North-West Himalayas: B Chromosomes in Artemisia gmelini Weber ex Stechm

Present work is a part of our studies on the cytological details of some species of Artemisia L. inhabiting Ladakh region of Jammu and Kashmir state. Of the six populations investigated for three different species (Artemisia sieversiana Ehrh. ex Willd., A. tournefortiana L. and A. gmelinii Weber ex Stechm.), some variations were noticed only for Artemisia gmelinii. The species occurring in Leh region at altitudinal range of 3992 masl is diploid with 2n = 18 (n = 9). In one of the population of the species, sprawling in Hemis region (4009 masl), В chromosome was found to be present in addition to the diploid chromosome complement. Comparison of the different morphological and reproductive features revealed that the population with В chromosome had reduced vigour.

Correction: Karyotype evolution in Phalaris (Poaceae): The role of reductional dysploidy, polyploidy and chromosome alteration in a wide-spread and diverse genus.

[This corrects the article DOI: 10.1371/journal.pone.0192869.].

Karyotype evolution in Phalaris (Poaceae): The role of reductional dysploidy, polyploidy and chromosome alteration in a wide-spread and diverse genus.

Karyotype characteristics can provide valuable information on genome evolution and speciation, in particular in taxa with varying basic chromosome numbers and ploidy levels. Due to its worldwide distribution, remarkable variability in morphological traits and the fact that ploidy change plays a key role in its evolution, the canary grass genus Phalaris (Poaceae) is an excellent study system to investigate the role of chromosomal changes in species diversification and expansion. Phalaris comprises diploid species with two basic chromosome numbers of x = 6 and 7 as well as polyploids based on x = 7. To identify distinct karyotype structures and to trace chromosome evolution within the genus, we apply fluorescence in situ hybridisation (FISH) of 5S and 45S rDNA probes in four diploid and four tetraploid Phalaris species of both basic numbers. The data agree with a dysploid reduction from x = 7 to x = 6 as the result of reciprocal translocations between three chromosomes of an ancestor with a diploid chromosome complement of 2n = 14. We recognize three different genomes in the genus: (1) the exclusively Mediterranean genome A based on x = 6, (2) the cosmopolitan genome B based on x = 7 and (3) a genome C based on x = 7 and with a distribution in the Mediterranean and the Middle East. Both auto- and allopolyploidy of genomes B and C are suggested for the formation of tetraploids. The chromosomal divergence observed in Phalaris can be explained by the occurrence of dysploidy, the emergence of three different genomes, and the chromosome rearrangements accompanied by karyotype change and polyploidization. Mapping the recognized karyotypes on the existing phylogenetic tree suggests that genomes A and C are restricted to sections Phalaris and Bulbophalaris, respectively, while genome B occurs across all taxa with x = 7.

Polyploidy as a chromosomal component of stochastic noise: variable scalar multiples of the diploid chromosome complement in the invertebrate species Girardia schubarti from Brazil.

Chromosome stoichiometry, a form of genetic plasticity, specifically refers to variation in the standard diploid genomic composition of an individual or species. In the present work, freshwater planarians (Girardia schubarti) were analyzed to recognize variations in chromosomal stoichiometry especially of complete ploidal change between specimens, within specimens and between cells within specimens and any relations they might have with selected components of phenotypic plasticity. Homoploid polyploids for the group reached rational scalar multiples (e.g. tetraploids) or irrational scalar multiples (e.g. triploids). Karyotypic mosaics emerged where individual cells presented polyploid multiples in arithmetic and geometric progressions. Ploidal multiplicity, a chromosomal component of stochastic noise, had positive phenotypic effects (increased dimensions) on morphologic criteria of body length, body width and dorsal surface reflecting a significant genotypic plasticity (GP) and robust phenotypic plasticity (PP). Variable but significant association of genotypic plasticity with robust phenotypic variance suggests kinetics of phenotypic homeostasis that is species-specific permitting phenotypic adaptability to environmental variables by means of GP. That association is diminished, deactivated or lost in more advanced and more complex organisms.

Meiotic chromosome behavior of the male-fertile allotriploid lily cultivar 'Cocossa'.

Cytological observations of microsporogenesis in the allotriploid lily cultivar 'Cocossa' showed that viable pollen production could be attributed mainly to disoriented spindles, abnormal cytokinesis, and cytomixis during male meiosis. To identify the reasons why the allotriploid lily cultivar 'Cocossa' can produce aneuploid and euploid functional male gametes and can be used as the paternal parent in lily introgression breeding, we performed a detailed investigation of microsporogenesis using the conventional cytological methods. The allotriploid not only produced single pollen grains with variable sizes but also produced adherent pollen grains. Pollen viability was estimated at 50.1% based on staining and 30.8% based on germination. Based on the chromosomal analysis of BC2 plants derived from Oriental cultivars (♀) crossed with the OOT cultivar 'Cocossa' (♂), it was concluded that the objective allotriploid contributed haploid (x), diploid (2x), and aneuploid chromosome complements. Common meiotic abnormalities were observed, indicating the high genetic imbalance of this allotriploid. In addition to normally oriented metaphase II spindles (linear and perpendicular), abnormal spindles, such as parallel, tripolar, fused, and multiple spindles, accounted for 6.21, 6.41, 14.27, and 1.17%, respectively. Tripolar and fused spindles resulted in the production of triads and dyads, which contributed to unreduced pollen production. Some microsporocytes exhibited complete or partial absence of cytokinesis, which led to relatively high frequencies of monads, dyads, and triads. Furthermore, the phenomenon of cytomixis during microsporogenesis occurred mainly in the first meiotic prophase and early development of pollen grains, which we assume is a possible cause of unreduced gamete generation. Our study offers a new resource for lily introgression breeding.

Acquired uniparental disomy of chromosome 9p in hematologic malignancies.

Acquired uniparental disomy (aUPD) is a common and recurrent molecular event in human cancers that leads to homozygosity for tumor suppressor genes as well as oncogenes, while retaining the diploid chromosomal complement. Because of the lack of copy number change, aUPD is undetectable by comparative genome hybridization, so the magnitude of this genetic change was underappreciated in the past. 9p aUPD was first described in 2002 in patients with polycythemia vera (PV). Since then, systematic application of genomewide single-nucleotide polymorphism arrays has indicated that 9p aUPD is the most common chromosomal aberration in myeloproliferative neoplasms (MPNs), contributing to discovery of the PV-defining mutation JAK2V617F21. It was also found in other myeloid and lymphoid malignancies, though at a relatively lower frequency. By leading to JAK2V617F 23 homozygosity, 9p aUPD plays a causal role in the development of PV and is also associated with less favorable clinical outcomes. It is also possible that new targets other than JAK2V617F 25 are present within 9p aUPD that may contribute to diversity of PV outcome and phenotype. This review summarizes recent discoveries on 9p aUPD in hematologic malignancies and discusses possible underlying mechanisms and potential roles of 9p aUPD in the pathogenesis of PV, the relationship between 9p aUPD and JAK2V617F29, and possible new cancer-related targets within the 9p aUPD region.

First report on a multiple sex chromosome system (X<sub>1</sub>X<sub>2</sub>X<sub>3</sub>0) and population variations in the frequency of ring bivalents in Pyrrhocoridae (Hemiptera: Heteroptera)

The family Pyrrhocoridae (Hemiptera: Heteroptera) is characterized by a modal diploid chromosome number of 16 (♂) rang- ing from 12 to 33 and simple (X0), multiple (X 1 X 2 0) and neo-sex chromosome systems (neoX-neoY). Out of about 340 known species, only 22 species belonging to 7 genera have to date been cytogenetically analysed. In the present study, the chromosome complement and meiotic details of one species, Odontopus nigricornis Stal has been revised, whilst that of another species, Antilochus russus Stal has been cytogenetically analyzed for the first time. The diploid chromosome complement of O. nigricornis is 2n (♂) = 25 = 22A + X 1 X 2 X 3 0; the first time this particular multiple sex chromosome system has been reported in the Pyrrhocoridae. Three sex chromosomes mostly remain intimately associated during male meiosis and their number was confirmed at diplotene and anaphase II, where they dissociate slightly to become distinct. Meiosis is post-reductional for sex chromosomes. However, unlike other pyrrhocorids with mul- tiple X chromosomes, the X 1 , X 2 and X 3 lie outside the autosomal ring on the metaphase plate during both divisions. The male diploid chromosome complement of A. russus was found to be 2n = 27 = 26A + X0. Apart from the typical meiotic features of heteropterans, the latter species shows inter- and intra-population variations in frequency of ring bivalents.

Establishment and characterization of a telomerase-immortalized canine bronchiolar epithelial cell line.

Dogs are susceptible to infectious diseases that occur primarily in the respiratory tract. The airway epithelium acts as a first line of defense and is constantly exposed to microorganisms present in the environment. Respiratory epithelial cells have recently gained wide use as a cell model for studying the pathogenesis of human, murine or swine respiratory pathogen infections. However, studies of the pathogenic mechanisms of canine pathogens have been hindered by the lack of reliable respiratory cell lines. Here, we cultured primary canine bronchiolar epithelial cells (CBECs), whose characteristics were confirmed by their expression of the epithelial cell-specific marker cytokeratin 18, and have provided protocols for their isolation and ex vivo expansion. Further, we established immortalized CBECs containing the human telomerase reverse transcriptase (hTERT) gene via transfection of primary CBECs with the recombinant plasmid pEGFP-hTERT. Immortalized bronchiolar epithelial cells (hTERT-CBECs) retain the morphological and functional features of primary CBECs, as indicated by reverse transcriptase polymerase chain reaction, proliferation assays, karyotype analysis, telomerase activity assay, and Western blotting, which demonstrate that hTERT-CBECs have higher telomerase activity, an extended proliferative lifespan, and a diploid complement of chromosomes, even after Passage 50. Moreover, this cell line is not transformed, as evaluated using soft agar assays and tumorigenicity analysis in nude mice, and can therefore be safely used in future studies. The isolation and establishment of stable hTERT-CBECs is of great importance for use as an in vitro model for mechanistic studies of canine pathogenic infections.

Cytogenetic Features of Human Head and Body Lice (Phthiraptera: Pediculidae).

The genus Pediculus L. that parasitize humans comprise two subspecies: the head lice Pediculus humanus capitis De Geer and the body lice Pediculus humanus humanus De Geer. Despite the 200 yr of the first description of these two species, there is still a long debate about their taxonomic status. Some authors proposed that these organisms are separate species, conspecifics, or grouped in clades. The sequencing of both forms indicated that the difference between them is one gene absent in the head louse. However, their chromosomal number remains to be determined. In this study, we described the male and female karyotypes, and male meiosis of head and body lice, and examined the chromatin structure by means of C-banding. In P. h. humanus and P. h. capitis, the diploid chromosome complement was 2 n = 12 in both sexes. In oogonial prometaphase and metaphase and spermatogonial metaphase, it is evident that chromosomes lack of a primary constriction. No identifiable sex chromosomes or B chromosomes were observed in head and body lice. Neither chiasmata nor chromatin connections between homologous chromosomes were detected in male meiosis. The meiotic behaviour of the chromosomes showed that they are holokinetic. C-banding revealed the absence of constitutive heterochromatin. Our results provide relevant information to be used in mapping studies of genes associated with sex determination and environmental sensing and response.

Aspectos genéticos de la mola hidatidiforme

The hydatidiform mole (HM) consists in an abnormal pregnancy, featured by hydropic degeneration of the chorionic villi and trophoblastic hyperplasia. It is classified as complete hydatidiform mole (CHM) and partial hydatidiform mole (PHM) and has an incidence in Europe and North America of 1-3:1,000 pregnancies, in Mexico the incidence has been estimated in 2.4:1,000 pregnancies. From 10 to 30% of the HM complicate with persistent trophoblastic gestational disease. Almost 75% are classified as CHM, which have a diploid androgenetic chromosome complement; histopathological features are diffuse hydropic edema, and trophoblastic hyperplasia of the syncytiotrophoblast, cytotrophoblast and intermediate trophoblast. The remaining 25% are classified as PHM, with a triploid chromosome complement; histopathological features are the presence of two villi populations, and syncytiotrophoblast and cytotrophoblast hyperplasia. Most of the HMs are sporadic, with general recurrence in 0.6 to 2.57% of total cases. The occurrence of two or more molar pregnancies in the same patient is known as recurrent mole, in this case there are two groups: those with RM of androgenetic origin and those with a diploid complement and biparental origin (DCBP). In the first case it's rare to have a third molar pregnancy and reproductive outcome is better, in those patients with DCBP, their etiology has been related with maternal metilation alterations in molar tissue, the majority of patients with this type of molar pregnancy have mutations in NLRP7 and KHCD3L genes, the reproductive outcome is adverse, with a probability of a normal term pregnancy of 5-7%.

Revelation of heterochromatin heterogeneity in Sarcophagid chromosomes using DNA ligand Mithramycin

The flesh-flies of the genus Sarcophaga (Diptera: Sarcophagidae) are prevalent world-wide, have great medical and veterinary importance forming an important group of myiasis producers. The diploid chromosome complements of the genus Sarcophaga comprise of five homologous pairs of autosomes and a pair of sex chromosomes (XX in females and XY in males). Heterochromatin of Sarcophaga species has been studied and characterized. The modification of permanently condensed patterns of chromosomes of the two Sarcophaga species, Sarcophaga argyrostoma and Sarcophaga ruficornis, by means of a GC specific DNA ligand Mithramycin (0.05μg/ml) proved to be useful for the analysis of heterochromatic regions of the chromosomes after DAPI staining. The pericentric regions of all the autosomes revealed fluorescent bands in both the species while both the X- and Y- chromosomes revealed differential staining due to differences in base sequence organization in these areas. Therefore, the present investigation was carried out in...

Study of the mitotic and meiotic chromosomes of sotol (Dasylirion cedrosanum Trel.)

The genus Dasylirion is a group of plants typically present in the Chihuahuan Desert, perennial, with a dioecious sexual behavior and commonly called sotoles. This genus has been little studied from the biological point of view, and the bases of its reproductive response remain unknown. In this work we studied the chromosome number and meiotic response of Dasylirion cedrosanumin the county of Saltillo, Coahuila, located at the North East of Mexico. For the preparation of mitotic chromosomes, we used a technique based on enzymatic treatment with pectolyase and cellulase, as well as staining with acetocarmin dye. For the study of meiosis, male flower buds were collected, fixed and stained for analysis with the same dye. As a result, the gametic (n = x = 19) and somatic chromosome (2n = 38) numbers of D. cedrosanum are reported for the first time, being consistent with previous findings in other Dasylirion species, which points to a constant ploidy level across the genus. Variation was observed in the morphology and size of the somatic chromosomes, with types ranging from submetacentric to subtelocentric, and sizes oscillating in a range of 4.43 µm, with an average total length of 112.38 µm for the diploid chromosome complement. This shows that the chromosome complementof D. cedrosanom would belong to a 3B classification of Stebins, with a medium variation between chromosome lengths and low chromosome asymmetry. This variation indicates the feasibility of constructing a chromosome ideotype for this species. The meiotic chromosome pairing showed a chromosome behavior consistent with a disomic inheritance characteristic of a diploid species, with prevalence of ring and chain bivalents, typically without pairing abnormalities. Bivalent configurations in all cases were symmetrical. The normal and symmetrical meiotic pairing indicates a balanced production of gametes, and suggests the absence of heteromorphicsex determination.

Restricted development of mouse triploid fetuses with disorganized expression of imprinted genes.

Eukaryotic species commonly contain a diploid complement of chromosomes. The diploid state appears to be advantageous for mammals because it enables sexual reproduction and facilitates genetic recombination. Nonetheless, the effects of DNA ploidy on mammalian ontogeny have yet to be understood. The present study shows phenotypic features and expression patterns of imprinted genes in tripronucleate diandric and digynic triploid (DAT and DGT) mouse fetuses on embryonic day 10.5 (E10.5). Measurement of crown-rump length revealed that the length of DGT fetuses (1.87 ± 0.13 mm; mean ± standard error of the mean) was much smaller than that of diploid fetuses (4.81 ± 0.05 mm). However, no significant difference was observed in the crown-rump length between diploid and DAT fetuses (3.86 ± 0.43 mm). In DGT fetuses, the expression level of paternally expressed genes, Igf2, Dlk1, Ndn, and Peg3, remained significantly reduced and that of maternally expressed genes, Igf2r and Grb10, increased. Additionally, in DAT fetuses, the Igf2 mRNA expression level was approximately twice that in diploid fetuses, as expected. These results provide the first demonstration that imprinted genes in mouse triploid fetuses show distinctive expression patterns independent of the number of parental-origin haploid sets. These data suggest that both DNA ploidy and asymmetrical functions of parental genomes separately influence mammalian ontogeny.

A new and aberrant species of Dugesia (Platyhelminthes, Tricladida, Dugesiidae) from Madagascar.

In this paper we report a new species of Dugesia of the family Dugesiidae from Madagascar, representing the fourth species of freshwater planarian known from this global biodiversity hotspot. In some respects the new species is aberrant, when compared with its congeners, being characterized by a head with smoothly rounded auricles, a peculiar course of the oviducts, including the presence of a common posterior extension, and by the asymmetrical openings of the vasa deferentia at about halfway along the seminal vesicle. Further, it is characterized by a ventral course of the ejaculatory duct with a terminal opening, very long spermiducal vesicles and unstalked cocoons. Its diploid chromosome complement with 18 chromosomes represents an uncommon feature among fissiparous species of Dugesia.