Diploid Chromosome Research Articles

Karyotype Analysis of Four Blind Snake Species (Reptilia: Squamata: Scolecophidia) and Karyotypic Changes in Serpentes

The suborder Serpentes is divided into 2 infraorders, Scolecophidia and Alethinophidia, which diverged at an early stage of snake diversification. In this study, we examined karyotypes of 4 scolecophidian species (Letheobia simonii, Xerotyphlops vermicularis, Indotyphlops braminus, and Myriopholis macrorhyncha) and performed FISH with 18S-28S rDNA as well as microchromosomal and Z chromosome-linked genes of Elaphe quadrivirgata (Alethinophidia) to investigate the karyotype evolution in the scolecophidian lineage. Diploid chromosome numbers of X. vermicularis and L. simonii were 30 (16 macrochromosomes and 14 microchromosomes) and 32 (16 macrochromosomes and 16 microchromosomes), respectively. The karyotype of a female M. macrorhyncha consisted of 15 macrochromosomes and 19 microchromosomes, including a heterochromatic microchromosome, indicating the presence of a heteromorphic chromosome pair. E. quadrivirgata Z-linked genes mapped to chromosome 4 of M. macrorhyncha, not to the heteromorphic pair. Therefore, M. macrorhyncha may have differentiated ZW sex chromosomes which are not homologous to those of E. quadrivirgata. One of the E. quadrivirgata microchromosomal genes mapped to the terminal region of chromosome 4q in X. vermicularis, suggesting that fusions between microchromosomes and macrochromosomes occurred in this species. rDNA was localized in different macrochromosomal pairs in the 2 diploid scolecophidian snakes examined here, whereas the gene location in a microchromosomal pair was conserved in 5 alethinophidian species examined. These results might imply the occurrence of chromosome fusions in the scolecophidian lineages. In I. braminus, a unique parthenogenetic snake with a triploid karyotype (21 macrochromosomes and 21 microchromosomes), morphological heteromorphisms were identified in chromosomes 1 and 7. Such heteromorphisms in 2 chromosomes were also observed in individuals from distant locations in the broad distribution range of this species, suggesting that the heteromorphisms were fixed in the genome at an early stage of its speciation.

Cytogenetics and genetic introgression from wild relatives in soybean

Cultivated soybean, wild soybean, and 23 perennial Glycine species contain 2n = 40 chromosomes. Accessions of G. hirticaulis and G. tabacina have diploid (2n = 40) and tetraploid (2n = 80) chromosome numbers. In contrast, G. tomentella includes accessions with four cytotypes (2n = 38, 40, 78, or 80). Meiosis of G. max and G. soja F1 is normal and gene exchange is easy. Occasionally, accessions of the two species differ by chromosome structural changes (reciprocal translocation/paracentric inversion). The segregating populations inherit undesirable traits such as vining, lodging susceptibility, lack of complete leaf abscission, seed shattering, and small black coated seeds because of genetic drag. The introgression of useful genes from 26 wild perennial Glycine species to soybean has been restricted because of crossability barriers and requires extensive hybridization, immature seed rescue, and cytogenetic manipulations. This review paper discusses cytogenetics, gene pools of the soybean and the production of fertile G. max plants using 78-chromosome G. tomentella (PI 441001) as a paternal and maternal parent in crosses with G. max cv. ‘Dwight’ (2n = 40). Thus, reporting breaking of the intersubgeneric crossability barriers for the first time.

First report on the chromosomal analysis of three species of tribe Eristalini (Diptera: Syrphidae) from outer Himalayas, India

In the present study, the chromosomes of three species of tribe Eristalini (family Syrphidae) were studied for karyotypic details, morphometric data, C-banding and meiosis. Two species Eristalinus laetus and E. obscuritarsis showed 2n = 10 diploid chromosome number and the remaining third species E. obliquus revealed 2n = 12 chromosomes as diploid number. All the three species exhibited XY sex mechanism in males. The morphology of Y chromosome was similar in all the three species studied. C-banding revealed the presence of constitutive heterochromatin at pericentromeric locations and established the euchromatic or heterochromatic nature of sex chromosomes. Meiotic observations included leptotene, pachytene, diplotene, metaphase-II and anaphase-II. The study is useful in chromosomal evolution and in the solution of taxonomic problems within the family Syrphidae.

First Cytogenetic Analysis of Eratigena agrestris (Araneae: Agelenidae) From Turkey.

In this study, chromosomal characteristics of Eratigena agrestris (Agelenidae) were investigated for the first time. Karyotype features including diploid chromosome number, sex chromosome system, chromosome morphology, and meiotic behavior were obtained from specimens collected in two localities of Mediterranean region. A spreading method including dissection, hypotonization, fixation, and staining was used to prepare the chromosome slides. In a total, 10 adult males were used due to having high numbers of dividing cells. Cytogenetical results showed that the diploid chromosome number and sex chromosome system was 2n♂ = 42 (X1X20). The sex chromosomes were identified tentatively. All chromosomes were telocentric. Relative chromosome lengths of autosomal pairs ranged between 5.65 and 3.32%, and relative chromosome lengths of X1 and X2 were 5.33 and 4.19%, respectively. In the first meiotic division stages, bivalents usually had one chiasma, but some had two chiasmata. At the end of the meiosis, two kinds of nuclei, with or without sex chromosomes, have occurred. These results contribute to a better characterization of the Agelenidae cytogenetic.

Chromosome studies on freshwater prawn, Macrobrachium lanchesteri (Decapoda, Palaemonidae) from Thailand

The chromosomes of freshwater prawn (Macrobrachium lanchesteri) were characterized by means of conventional Giemsa-, DAPI-, silver-staining and G-banding techniques. The number of diploid chromosome and fundamental number were 2n = 116 and 226, respectively. The karyotype consisted of 54 metacentric, 46 submetacentric, 10 acrocentric and 6 telocentric chromosome pairs. The karyotype formula could be deduced as 2n (116) = L 24 m + L 8 a + M 12 m + M 6 sm + M 2 a + S 18 m + S 40 sm + S 6 t . Heterochromatic regions were located in the centromere and pericentromeric regions of most chromosomes, and NORs were found on two pairs of small chromosomes. G-band karyotype of M. lanchesteri was provided for the first time.

INFECTED FRESHWATER SNAILS, BIOMPHALARIA ALEXANDRINA, THE INTERMEDIATE HOST OF SCHISTOSOMA MANSONI

The objective was to study the chromosomes of Biomphalaria alexandrina snails (class Gastropoda) in control and infected state which could be helpful in understanding how host-parasite relationships in feasible and effective control measures. The chromosomal changes were studied using the air-drying method. The results showed that B. alexandrina had a diploid chromosome number, 2n = 36. Also, the meiotic stages were detected as early- leptotene and late leptotene, zygotene, diplotene, metaphase I. The result also revealed the presence of a primitive sperm, with a conical head and a very long, uni-flagellate tail. A comparative meiotic chromosome analysis between the control and infected ones showed some significant differences, as pachytene and diplotene were more condensed.

Chromosome map of the Siamese cobra: did partial synteny of sex chromosomes in the amniote represent \u201ca hypothetical ancestral super-sex chromosome\u201d or random distribution?

BackgroundUnlike the chromosome constitution of most snakes (2n=36), the cobra karyotype shows a diploid chromosome number of 38 with a highly heterochromatic W chromosome and a large morphologically different chromosome 2. To investigate the process of sex chromosome differentiation and evolution between cobras, most snakes, and other amniotes, we constructed a chromosome map of the Siamese cobra (Naja kaouthia) with 43 bacterial artificial chromosomes (BACs) derived from the chicken and zebra finch libraries using the fluorescence in situ hybridization (FISH) technique, and compared it with those of the chicken, the zebra finch, and other amniotes.ResultsWe produced a detailed chromosome map of the Siamese cobra genome, focusing on chromosome 2 and sex chromosomes. Synteny of the Siamese cobra chromosome 2 (NKA2) and NKAZ were highly conserved among snakes and other squamate reptiles, except for intrachromosomal rearrangements occurring in NKA2. Interestingly, twelve BACs that had partial homology with sex chromosomes of several amniotes were mapped on the heterochromatic NKAW as hybridization signals such as repeat sequences. Sequence analysis showed that most of these BACs contained high proportions of transposable elements. In addition, hybridization signals of telomeric repeat (TTAGGG)n and six microsatellite repeat motifs ((AAGG)8, (AGAT)8, (AAAC)8, (ACAG)8, (AATC)8, and (AAAAT)6) were observed on NKAW, and most of these were also found on other amniote sex chromosomes.ConclusionsThe frequent amplification of repeats might involve heterochromatinization and promote sex chromosome differentiation in the Siamese cobra W sex chromosome. Repeat sequences are also shared among amniote sex chromosomes, which supports the hypothesis of an ancestral super-sex chromosome with overlaps of partial syntenies. Alternatively, amplification of microsatellite repeat motifs could have occurred independently in each lineage, representing convergent sex chromosomal differentiation among amniote sex chromosomes.

Cytogenetic Analysis of Tegenaria elysii (Araneae: Agelenidae)

There are 55 species of agelenid spiders in our country and the genus Tegenaria represents the widest group in terms of species number. In this study, it was aimed to investigate the cytogenetic properties of Tegenaria elysii species. Chromosomes were obtained by making some modifications to the method of Pekár and Král (2001). Hypotonic, fixation and staining steps were applied to the gonads respectively. As a result, the number of diploid chromosomes and the sex chromosome system were found as 2n=42, ♂X1X20/♀X1X1X2X2. Total relative lengths of chromosomes decreased gradually from 6,83% to 3,31%. Sex chromosomes which positive heteropycnotics in the stage of meiosis I have been detected to be isopycnic in the stage of meiosis II. 20 autosomal bivalent and two sex chromosomes were identified in which diplotene and diakinesis stages.

Discovery and annotation of a novel transposable element family in Gossypium

BackgroundFluorescence in situ hybridization (FISH) is an efficient cytogenetic technology to study chromosome structure. Transposable element (TE) is an important component in eukaryotic genomes and can provide insights in the structure and evolution of eukaryotic genomes.ResultsA FISH probe derived from bacterial artificial chromosome (BAC) clone 299N22 generated striking signals on all 26 chromosomes of the cotton diploid A genome (AA, 2x=26) but very few on the diploid D genome (DD, 2x=26). All 26 chromosomes of the A sub genome (At) of tetraploid cotton (AADD, 2n=4x=52) also gave positive signals with this FISH probe, whereas very few signals were observed on the D sub genome (Dt). Sequencing and annotation of BAC clone 299N22, revealed a novel Ty3/gypsy transposon family, which was named as ‘CICR’. This family is a significant contributor to size expansion in the A (sub) genome but not in the D (sub) genome. Further FISH analysis with the LTR of CICR as a probe revealed that CICR is lineage-specific, since massive repeats were found in A and B genomic groups, but not in C–G genomic groups within the Gossypium genus. Molecular evolutionary analysis of CICR suggested that tetraploid cottons evolved after silence of the transposon family 1–1.5 million years ago (Mya). Furthermore, A genomes are more homologous with B genomes, and the C, E, F, and G genomes likely diverged from a common ancestor prior to 3.5–4 Mya, the time when CICR appeared. The genomic variation caused by the insertion of CICR in the A (sub) genome may have played an important role in the speciation of organisms with A genomes.ConclusionsThe CICR family is highly repetitive in A and B genomes of Gossypium, but not amplified in the C–G genomes. The differential amount of CICR family in At and Dt will aid in partitioning sub genome sequences for chromosome assemblies during tetraploid genome sequencing and will act as a method for assessing the accuracy of tetraploid genomes by looking at the proportion of CICR elements in resulting pseudochromosome sequences. The timeline of the expansion of CICR family provides a new reference for cotton evolutionary analysis, while the impact on gene function caused by the insertion of CICR elements will be a target for further analysis of investigating phenotypic differences between A genome and D genome species.

Karyotype and chromosomal characteristics of rDNA of Cobitisstrumicae Karaman, 1955 (Teleostei, Cobitidae) from Lake Volvi, Greece.

The karyotype of Greek cobitid fish Cobitisstrumicae Karaman, 1955, from Lake Volvi, Greece, a representative of one of its two major intraspecific phylogenetic lineages, was analysed by means of sequential Giemsa-staining, C-banding, silver-staining, CMA3 fluorescence banding and also by in situ hybridization (FISH) with rDNA probe. The diploid chromosome number was 2n = 50, karyotype composed of 10 pairs of metacentric to submetacentric and 15 pairs of subtelocentric to acrocentric chromosomes. The nucleolus organizer regions (NORs) as revealed by Ag- and CMA3 staining and FISH were situated in the telomeric region of the fourth submetacentric chromosome pair. The chromosomes contained very low content of C-positive heterochromatin. No heteromorphic sex chromosomes were detected. This first karyotype report for any species of lineage Bicanestrinia Băcescu, 1962 shows a simple karyotype dominated by acrocentric chromosomes and possessing single NOR-bearing chromosome pair. Cytotaxonomic implications of this finding for the taxonomy of the genus Cobitis Linnaeus, 1758 are further discussed.

Apoptosis in Spermiogenesis of Multiple Robertsonian Heterozygotes of Mus musculus domesticus

Mus musculus domesticus is a species that is characterized by a diploid number of 40 chromosomes, all telocentrics (acrocentrics). In natural populations of Mus with high frequency Robertsonian chromosome translocations (RBs), a fusion at centromere-level between two autosomal telocentric, producing metacentric Rb chromosomes and a variety of natural subspecies with diploid chromosome numbers below 40. Rb chromosomes do not affect the viability of individuals but mainly fertility of Rb heterozygotes. In their meiosis the metacentric Rb and the homologous telocentrics form trivalents that have problems in synapsis and segregation. This paper presents a comparative analysis of spermatogenesis considering the stages of the epithelium and the number of germ cells loss by apoptosis comparing heterozygote males 2n=32, carriers 8 trivalents, and homozygotes 2n=40 and 2n=24. It was found that the number of spermatocytes in first prophase was similar in the different seminiferous epithelium stages in all the chromosome constitutions. In the 2n=32 heterozygotes a significant decreased number of spermatids was reflected in the proportion of spermatocytes and spermatids that was 1:1.7. In the homozygote males rare germ cell in apoptosis (positive for caspase 3) were observed, which were mainly concentrated in the XII stage of the seminiferous epithelium. In heterozygote spermatocytes apoptotic germ cell number was significantly higher than that registered in homozygote males, and generally correspond to spermatocytes in meiotic divisions. This selective removal of cells possibly carrying anomalies, either in chromosome alignment or segregation, is consistent with the smaller number of spermatids and the relative sub-fertility observed in 2n=32 Rb heterozygotes.

Karyotype Characterization of Nine Periwinkle Species (Gastropoda, Littorinidae).

Periwinkles of the family Littorinidae (Children, 1834) are common members of seashore littoral communities worldwide. Although the family is composed of more than 200 species belonging to 18 genera, chromosome numbers have been described in only eleven of them. A molecular cytogenetic analysis of nine periwinkle species, the rough periwinkles Littorina arcana, L. saxatilis, and L. compressa, the flat periwinkles L. obtusata and L. fabalis, the common periwinkle L. littorea, the mangrove periwinkle Littoraria angulifera, the beaded periwinkle Cenchritis muricatus, and the small periwinkle Melarhaphe neritoides was performed. All species showed diploid chromosome numbers of 2n = 34, and karyotypes were mostly composed of metacentric and submetacentric chromosome pairs. None of the periwinkle species showed chromosomal differences between male and female specimens. The chromosomal mapping of major and minor rDNA and H3 histone gene clusters by fluorescent in situ hybridization demonstrated that the patterns of distribution of these DNA sequences were conserved among closely related species and differed among less related ones. All signals occupied separated loci on different chromosome pairs without any evidence of co-localization in any of the species.

Establishment and characterization of a cell line from tilapia brain for detection of tilapia lake virus.

Tilapia lake virus (TiLV) is an emerging disease threatening tilapia culture in many parts of the world. A cell line from the brain of tilapia, which was named TiB, was established, characterized and subcultured with more than 100 passages. The TiB cell line was optimally maintained at 27°C using medium 199 (M199) supplemented with 10% foetal bovine serum (FBS). Chromosome analysis revealed that 60% of TiB cells at passage 5 maintained the modal chromosome number 2n=44, while at passage 60, there were 43% of TiB cells with the diploid chromosome number 2n=50. A significant cytopathic effect was observed in TiB cells after infection with tilapia lake virus (TiLV-2017A), and the viral replication in the cells was confirmed by transmission electron microscopy, immunofluorescence assays and viral titres, indicating the susceptibility of TiB cells to TiLV-2017A. The viral titres of TiLV-2017A in TiB cells reached 107.43 TCID50 /ml within 10days. The stable growth and susceptibility to fish viruses make TiB cells a useful tool for fish virus-host cell interaction and for immune response of fish.

Karyomorphological studies from mitotic metaphases in three carp species

Karyological analysis of three carp species viz. Ctenopharyngodon idella, Hypophthalmichthyes molitrix, and Cyprinus carpio communis belonging to family Cyprinidae was carried out. The study samples of these species were collected from local fish farm in Haryana. The diploid chromosome number in C. idella was found to be 2n = 48, with 13 pairs of metacentric, 3 pairs of submetacentric and 8 pairs of acrocentric chromosomes. Chromosomal studies on the H. molitrix revealed the diploid chromosome number to be 2n = 48, with 6 pairs of metacentric, 6 pairs of submetacentric and 12 pairs of acrocentric chromosomes. The diploid chromosome number in C. c. communis was found to be 2n = 100, with 17 pairs of metacentric, 3 pairs of submetacentric, 1 pair of subtelocentric and 29 pairs of acrocentric chromosomes. Arm ratio, centromeric index and fundamental number of arms was also determined. The study reveals that diversification in these carp species of cyprinidae family is related to structural changes in chromosomes. Habitat conditions and anthropogenic activities might be responsible for incidence of pericentric inversions causing karyomorphological changes and thereby variation in karytype formulae vis-a-vis earlier reports.

First illustration of chromosomes and genetic system of Lecanodiaspidinae (Homoptera, Coccinea, Asterolecaniidae s.l.).

The karyotype of Psoraleococcusmultipori (Morrison, 1921) was studied for the first time, based on material from Indonesia (Sulawesi). The diploid chromosome number was found to be 18 in both males and females, but some cells contained also additional small chromosomal elements, probably B chromosomes. About 50 % of the studied embryos demonstrated paternal genome heterochromatinization of one haploid set of chromosomes (PGH) suggesting presence of a Lecanoid genetic system. The embryos with PGH are known to be always the male embryos in scale insects and so, bisexual reproduction may be presumed for P.multipori. The information provided represents the first probative cytogenetic data for the subfamily Lecanodiaspidinae Targioni Tozzetti, 1896 as a whole. A detailed morphological figure and photos of female and male embryonic cells are given. Additionally, it was discovered that the females of P.multipori exhibit complete ovoviviparity.

The karyotypes and evolution of ZZ/ZW sex chromosomes in the genus Characidium (Characiformes, Crenuchidae).

Available data on cytotaxonomy of the genus Characidium Reinhardt, 1867, which contains the greatest number of species in the Characidiinae (Crenuchidae), with 64 species widely distributed throughout the Neotropical region, were summarized and reviewed. Most Characidium species have uniform diploid chromosome number (2n) = 50 and karyotype with 32 metacentric (m) and 18 submetacentric (sm) chromosomes. The maintenance of the 2n and karyotypic formula in Characidium implies that their genomes did not experience large chromosomal rearrangements during species diversification. In contrast, the internal chromosomal organization shows a dynamic differentiation among their genomes. Available data indicated the role of repeated DNA sequences in the chromosomal constitution of the Characidium species, particularly, in sex chromosome differentiation. Karyotypes of the most Characidium species exhibit a heteromorphic ZZ/ZW sex chromosome system. The W chromosome is characterized by high rates of repetitive DNA accumulation, including satellite, microsatellite, and transposable elements (TEs), with a varied degree of diversification among species. In the current review, the main Characidium cytogenetic data are presented, highlighting the major features of its karyotype and sex chromosome evolution. Despite the conserved karyotypic macrostructure with prevalent 2n = 50 chromosomes in Characidium, herein we grouped the main cytogenetic information which led to chromosomal diversification in this Neotropical fish group.

Isolation and culture of putative mesenchymal stem cells from equine umbilical cord Wharton’s jelly

Despite major progress and knowledge related to the application of adult stem cells, finding alternative sources for bone marrow MSCs has remained a challenge in both humans and animals. In the current study, two protocols namely sequential enzymatic tissue digestion and tissue explant techniques were tried for successful establishment of MSC culture. Umbilical tissues were isolated each time of foaling from five sequential foalings of Marwari mares. Total cell yield, their growth potential and cryopreservation potential were studied. Adherent cell colonies could be established using both isolation methods. Both the cell populations yielded from different protocols performed similarly in terms of population doubling and CFU number value. Additionally, the cells proliferated vigourously and displayed a similar morphology of mesenchymal stem cells. The MSCs were plastic adherent, colonogenic and their morphology was polygonal and fibroblast like. During the proliferation, the cells exhibited density dependent inhibition; analysis of microbial contamination from bacteria, mycoplasma and fungi were negative; the population doubling time of the MSCs isolated was 34.8 h and 40.2 h in enzymatic treatment and tissue explant methods respectively, and diploid chromosome number of the cells was 64, and the diploid frequency was higher than 80%. In conclusion, this study reveals that both the techniques proved to be non-invasive, efficient, simple and quick for isolation and establishment of MSC culture of extra embryonic tissues from equines.

Extensive karyotype variability of African fish genus Nothobranchius (Cyprinodontiformes).

Karyotypes of 65 species of the genus Nothobranchius Peters, 1868 were reviewed and of those 35 examined first time. The results of present study have shown that fishes of the genus Nothobranchius possessed highly diverse karyotypes. The diploid chromosome number (2n) ranged from 16 to 50. The most frequent 2n was 2n = 36 (in 35 species) while the second one 2n = 38 (in 13 species). Proportion of biarmed chromosomes varied from 0 to 95% between species. Diploid chromosome number variability apparently exists as a result of chromosomal fusions or fissions and extensive karyotypic formula alterations promoting by inversions. Multiple sex chromosomes of system X1X1X2X2/X1X2Y type were found only in karyotypes of 5 species. The extensive karyotype variability, unusual for teleosts, of genus Nothobranchius can be likely associated with the characteristics of its life cycle and inhabiting under unstable environment of East African savannah temporal pools.

Development and Characterization of a New Cell Line from Olive Flounder Paralichthys olivaceus.

A new embryonic cell line (OFEC-17FEN) derived from olive flounder Paralichthys olivaceus was developed. OFEC-17FEN cells were subcultured for <30 passages over ~200 days. OFEC-17FEN cells had a doubling time of 114.34 h and modal diploid chromosome number was 48. The pluripotency genes POU5f1 and NANOG were expressed in OFEC-17FEN cells. However, the lack of several pluripotency-related genes expression indicates that OFEC-17FEN cells are not stem cells. OFEC-17FEN cells transfected with plasmid pEGFP-c1 exhibited a strong green fluorescent signal at 48 h after transfection. Accordingly, OFEC-17FEN cells may be useful for both basic research and biotechnological application.

Report on Chromosome Number Along with Chrom So-mal Chimera and Abnormal Shaped Anaphase of Acmella Ciliata

&#x0D; Acmella ciliata(Kunth) synomyme Spilanthes acmella Murr. is a plant species under asteraceae family are investigated cytogenetically by orcein staining to find out chromosome number, chimeric status and overall mitotic cell division. The diploid chromosome number 2n=46 was found in most of the cells but some cells possess 2n =70 chromosomes in the same examined sample. So, we found two type cells according to their chromosome number which are indicated as type ‘a’ and ‘b’. The centromeric formulae of a type cell is 34m+6sm while 52m +18sm is for b type cells. The length of chromosomes range 3.68 to 2.30 µm in a type cell and 3.68 to 2.24 µm in b type cell that is approximately same in case of the length ranges. The total length of 2n chromosome complement of b type cell is greater than a type cell. The variable chromosome number indicates its chromosomal chimera. No satellites were found. Some cell possesses abnormal shaped anaphase which are clearly distinguishable to normal anaphase stage found in same species. Conventional karyotype analysis indicated that both type cell’s chromosome number are totally different with previous report. Therefore, the compilation of the above cytogenetical information proves that the Acmella ciliata showing variable chromosome number means its chromosomal chimera. This cytogenetical information will help in the study of plant chromosomal chimera in Bangladesh.&#x0D;