Fundamental Arm Number Research Articles

Chromosome Banding Properties of Neogobius fluviatilis (Pallas, 1814) (Perciformes, Gobiidae)

The monkey goby, Neogobius fluviatilis (Pallas, 1814) that distributed in Türkiye was studied cytogenetically for the first time. In this context, diploid chromosome number, chromosome morphology and also chromosomal banding properties (C-banding and Ag-NOR staining) of N. fluviatilis were revealed out. Chromosome slides were prepared from head kidney cells according to the air-drying technique. Chromosome slides were observed under the microscope and metaphases were photographed. The chromosomes were measured by digital caliper and karyotype was arranged manually. The diploid chromosome number was found as 46. Karyotype was composed with all uniarmed chromosomes. Fundamental arm number was calculated as 46 too. No heteromorphic sex chromosomes were determined in the karyotype. C-bands were detected on the pericentromeres of almost all chromosomes. Otherwise, two Ag-NORs were found in the silver-stained metaphases. This study revealed out chromosomal properties of N. fluviatilis from Türkiye with conventional cytogenetic techniques. This report may improve the cytogenetic data of the genus Neogobius.

Chromosomal analysis of Sander lucioperca (L., 1758) (Perciformes: Percidae) from Turkey

Sander lucioperca (pikeperch) is a percid fish species of high commercial value and potential for being aquaculture in Turkey. However, karyological studies are deficient for population of Turkey. So, the aim of this study is to carry out diploid chromosome number, karyotype formula, fundamental arm number and chromosomal banding properties (with C-banding and Ag-NOR staining) of S. lucioperca. Specimens of S. lucioperca were captured from Konya, Turkey and alive specimens carried to the laboratory. Chromosome obtaining was provided by using air-drying technique from the head kidney. Chromosome slides were prepared and banding procedures were applied. Result of the analysis, diploid chromosome number was found as 48 and karyotype of the pikeperch consist of 32 biarmed and 16 uniarmed chromosomes. Constitutive heterochromatin regions were observed on the pericentromeres of some of the chromosomes. Ag-NORs were determined on one pair of submetacentric chromosome. This report is the first that determines chromosomal properties of S. lucioperca from Turkey. This study may contribute the cytogenetic information of this species.

Karasu ırmağında (Erzurum) yayılış gösteren Chondrostoma regium'un (Teleostei: Leuciscidae) karyotipik analizleri

In this study, the karyotypic characteristics of Chondrostoma regium (Heckel, 1843) have been investigated. Fish samples were caught from the Karasu River (Euphrates River Basin) with fishing net. The live fish were transported to the laboratory and kept in aerated aquaria before the analyses. The karyotype analysis was performed in fish kidney and gill epithelium cells. It was determined that C. regium had 2n=50 chromosomes. In detail, the karyotype formula of C. regium was determined as 9 metacentric, 7 submetacentric, 1 subtelocentric and 8 telocentric chromosome pairs (18M+14SM+2ST+16T), and fundamental arm number was calculated as 82. Constitutive heterochromatin regions were determined on telomeres of the chromosomes. Nuclear orgnizer regions were detected on 21st chromosome. Karyotype symmetry/asymmetry index was calculated as 2.32. The karyotypes of gill and kidney cells were the same. No sex chromosomes were cytologically detected.

Karyology of an endemic Oxynoemacheilus simavicus (Balık & Bănărescu, 1978) (Teleostei: Nemacheilidae)

The diploid chromosome number and chromosome morphologies of endemic Oxynoemacheilus simavicus (Balik & Banarescu, 1978) were revealed out from Gediz River, Turkey. Metaphase chromosomes were obtained from head kidney cells. The diploid chromosome number was found as 50 and karyotype was consisted 13 pairs of biarmed and 12 pairs of uniarmed chromosomes. Fundamental arm number was calculated as 76. The obtained results shall contribute to nemacheilid chromosomal studies.

Cytogenetic Studies in Glossogobius giuris (Hamilton, 1822) Through NOR-Staining and FISH

The Glossogobius giuris (Gobiidae), tank goby—a species of goby fish, is native mainly to freshwater and estuaries and has importance in the aquarium trade. It is classified as least concern under IUCN Red List. Live individuals of this species were collected from Loktak Lake in Manipur for cytogenetic investigation to reveal the nucleolar organizer region (NOR) through silver nitrate (AgNO3) and chromomycin A3 (CMA3) staining as well as DAPI staining and single-color fluorescence in situ hybridization (FISH) using 18S rDNA sequence as probe. Analysis of more than 50 metaphase chromosome complement (obtained from colchicine–potassium chloride–Carnoy’s fixation–Giemsa staining procedures) showed the presence of 46 diploid chromosome numbers with all telocentric having fundamental arm number as 46 without any heteromorphic pair. One pairs of silver-stained NORs, situated terminally on the telocentric chromosome, were observed. Similarly, one pair of CMA3-positive sites were observed on the chromosome that suggested abundance of GC-rich repetitive DNAs in this region. One pair of 18S rDNA positive sites was observed on the telocentric chromosomes using FISH. These karyological features can be useful markers in cytotaxonomy and conservation of this species.

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.

Taxonomy and Evolution ofTropidurus(Iguania, Tropiduridae) Based on Chromosomal and DNA Barcoding Analysis

Abstract Tropidurus is a widespread genus of lizards in Brazilian biomes, particularly common in the state of Bahia, northeastern Brazil. However, genetic studies of populations and species of this group are still scarce. We used chromosomal and DNA barcoding analyses to examine 12 populations of five species of Tropidurus from semiarid (caatinga) and Atlantic forest portions of Bahia. All populations shared a karyotype with 2n = 36 divided into 12 metacentric and submetacentric chromosomes and 24 microchromosomes. The microchromosomes were acrocentric in most of species, but metacentric microchromosomes were observed in Tropidurus semitaeniatus, determining variation in fundamental number of arms from 48 to 52. One population of Tropidurus hispidus presented a supernumerary chromosome. Pericentromeric heterochromatin was detected in most microchromosomes and two pairs of macrochromosomes presented interstitial and pericentromeric C-bands. The nucleolar organizer regions (NORs) were single in Tropidurus e...

Karyomorphometric analysis of somatic chromosomes of selected seagrasses of families Hydrocharitaceae and Cymodoceaceae

Chromosome numbers of eleven seagrass species were determined. The highest chromosome number was recorded in Halodule spp. (2n=44) and the lowest chromosome number was observed in Cymodocea rotundata (2n=14). Chromosome numbers were identical or closely related among different species in the same genus. Karyomorphology was mapped for nine species (Halodule pinifolia, Halodule uninervis, Halodule wrightii, Syringodium isoetifolium, Enhalus acoroides, Halophila beccarii, Halophila ovalis (subsp. ovalis and ramamurthiana) Halophila ovata and Thalassia hemprichii). Length of the chromosomes of these species varied from 7.81 to 336.63μm while the fundamental arm number ranged between 36 and 85. The results confirm the karyotypic variation among the studied species, indicating that this characteristic can be used to confirm taxonomic identity of species which are morphologically very similar (eg. Halodule spp.). All tested species were diploid, except for Cymodocea rotundata.

Karyology of Mullus barbatus (Pisces, Perciformes) from the Mediterranean basin

Data on karyotypes of Mullus barbatus from the Black Sea (Taman Peninsula, Russia) are presented. Chromosome preparations were made using cells of the anterior parts of the kidney and thymus. The karyotype of the population under study consisted of 44 diploid chromosomes with fundamental arm number 52. The chromosomal divergences in fishes with similar ecology and geographical distribution to that of M. Barbatus are discussed.

Karyology of Puntius sophore (Pisces, Cypriniformes) from the Brahmaputra River, Assam, India

In this investigation karyotypes of Puntius sophore from the Brahmaputra River (Assam, India) are presented. Chromosome preparations were made using anterior parts of the kidney cells. The karyotype of the population under study consisted of 48 diploid chromosomes with fundamental arm number 54. The chromosomal divergences in P. sophore with different ecology and geographical distribution are discussed.

First chromosomal study of Mantophasmatodea: Karyotype of Karoophasma biedouwense (Austrophasmatidae)

We have investigated for the first time the chromosomes of Karoophasma biedouwense, a species belonging to the Mantophasmatodea, a recently discovered order of carnivorous insects. Our study has revealed that males of this species display testes with numerous seminal tubes (follicles), as in other Polyneoptera, and short tubular seminal vesicles embedded in a utricular gland. The karyotype consists of 2n = 12A + X and biarmed, meta/submetacentric chromosomes (fundamental number of arms: FN = 26) with blocks of heterochromatin around centromeres. The autosomes are classified into two size groups, one represented by a single, very large pair of autosomes, the other by five smaller pairs which constitute a continuous series gradually decreasing in size. Among monocentric orders of Polyneoptera, K. biedouwense shares its low chromosome number, 2n = 13, as also found with some Orthoptera (Acridoidea, Grylloidea, Gryllacridoidea). Male meiosis is of the classical pre-reductional type and the X(0) sex determination system is probably an ancestral state. Use of FISH along with an 18S rDNA probe revealed multiple ribosomal clusters, which most likely represent an apomorphic condition. We identified the ancestral insect telomeric sequence (TTAGG)n in the terminal areas of the chromosomes. Currently available data on the polyneopteran orders putatively related to Mantophasmatodea showed a wide variability of cytogenetic characteristics within and between them. The only character allowing some tentative inference to be made on the ancestry of K. biedouwense is its low chromosome number, the karyotypic pattern so far unreported for the Polyneoptera except in certain Orthoptera.

Cytogenetic studies in six species of Scinax (Anura, Hylidae) clade Scinax ruber from northern and northeastern Brazil.

Scinax species are still underrepresented in cytogenetic studies, mainly with respect to populations from northeastern and northern Brazil. In this study, we provide new chromosomal information on Scinax boesemani, S. camposseabrai, S. garbei, S. pachycrus, S. trilineatus and S. x-signatus, all belonging to clade S. ruber. They were collected at two locations in the Caatinga biome (northeastern Brazil) and at one in the Amazon (northern Brazil) biomes. Chromosomes were analyzed by conventional staining, C-banding, Ag-NOR staining, and fluorochrome staining. All species shared a modal diploid value of 2n = 24 and fundamental arm number (FN) of 48. Moreover, both chromosomal size and morphology were similar to other species in this Scinaxclade. C-banding revealed centromeric heterochromatin in all species, along with terminal species-specific C-bands in some species. Active nucleolar organizer regions (Ag-NORs) were identified at 11q in most species, except for S. boesemani and S. garbei (Ag-NORs at interstitial region of 8q). Differing from most anurans, GC-rich regions were not restricted to NORs, but also coincident with some centromeric and terminal C-bands. These data contribute to the cytotaxonomy of Scinax by providing chromosomal markers and demonstrating the occurrence of microstructural rearrangements and inversions on chromosomal evolution of Scinax.

The morphological, histological and cytogenetic characteristics of goldfishCarassius auratus(L.) × common carpCyprinus carpio(L.) hybrids

Morphology of hybrids between the goldfish (Carassius auratus) and common carp (Cyprinus carpio) are studied by biometric and meristic methods. Additionally, histological analyses concerning gonads as well as genetic characteristics of chromosomes are performed. Studied hybrids were morphologically very similar to a goldfish but possessed one pair of reduced posterior barbels. Most meristic and biometric indices had intermediate values when compared to parental species. Histological study showed that investigated hybrids produce gonads with germ cells. All studied males had gonads at the same stage of maturity (III stage). By contrast, female gonads were in various stages of development – from sexually immature to post-spawning stage. Karyotype characteristics were assessed in terms of chromosomes number, fundamental arm number and location of nucleolus organizer regions (NOR). The data obtained were compared with baseline karyotypes of species used for hybridization, based on information from the literat...

Preliminary cytogenetic study and report of ZZ/ZW sex chromosomes in the bullfrog, Hoplobatrachus tigerinus (Anura, Amphibia) from high altitude area of Jammu and Kashmir, India

Cytogenetic study of the Indian Bullfrog, Hoplobatrachus tigerinus was carried out using both conventional staining and banding methods, from Jammu and Kashmir. Karyotypes prepared by conventional staining in both male and female specimens showed diploid chromosome number as 2n = 26 and fundamental arm number as NF = 52. Karyotypes of both the sexes comprised of 13 pairs of biarmed chromosomes divided into two groups: first group of five pairs of larger metacentric or submetacentric chromosomes and second group of eight pairs of smaller metacentric or submetacentric chromosomes. Pair number 2, 3, and 4 among the first group and 8 and 9 among the second group were submetacentric chromosomes. All the other chromosomes in both the groups were metacentric. Meiotic stages observed were leptotene, diakinesis, metaphase-I and metaphase- II, from testicular cells of males. C-banding analysis of the species showed presence of centromeric C-bands in all the chromosomes of both male and female karyotypes. Female karyotype showed presence of completely heterochromatic homologue of the pair no. 8, which represented ZZ/ZW sex chromosome system in the species. NOR-banding showed presence of a pair of nucleolar organizer regions on the long arm of 6th pair in both the sexes.

Divergence of Repetitive DNA Sequences in the Heterochromatin of Medaka Fishes: Molecular Cytogenetic Characterization of Constitutive Heterochromatin in Two Medaka Species: Oryzias hubbsi and O. celebensis (Adrianichthyidae, Beloniformes)

The large biarmed chromosomes of Oryzias celebensis [2n = 36, fundamental arm number (FN) = 48] are considered to have resulted from fusions of acrocentric chromosomes in the ancestral karyotype of Oryzias, which is retained in O. hubbsi (2n = 48, FN = 48). To understand the molecular evolution of heterochromatin associated with karyotype reorganization in medaka fishes, we cloned 3 and 6 novel families of heterochromatin-related repetitive DNA sequences from O. hubbsi and O. celebensis, respectively, and characterized them using molecular cytogenetics. Two AT-rich repetitive sequences isolated from the genomic DNA of O. hubbsi, a 164-bp satellite DNA (OHU-RsaI-Scen) and a 177-bp telomere-specific repeat (OHU-RsaI-Stelo), were shown to be major components of the constitutive heterochromatin of centromeres and telomeres, respectively. A GC-rich 326-bp sequence, named OHU-AluI-M1, was colocalized with the 18S-28S ribosomal RNA gene cluster to a single autosomal pair of chromosomes and the W chromosome. In O. celebensis, 2 major satellite DNA sequences (the AT-rich 157-bp OCE-AluI-Scen sequence and the 186-bp OCE-HinfI-Scen sequence) were identified in the centromeric regions of almost all chromosomes. The 197-bp OCE-HinfI-S6 sequence was located in the centromeric and distal and/or interstitial heterochromatin of almost all chromosomes, and the 191-bp OCE-HinfI-S8 sequence was located in 6 pairs of chromosomes. Constitutive heterochromatin on the short arm of large submetacentric chromosome 5 was composed of at least 3 different repetitive sequences: the 171-bp OCE-AluI-S18 sequence, the 197-bp OCE-HinfI-S6 sequence and the 172-bp OCE-HinfI-S11 sequence. All families of repeated sequences showed no nucleotide sequence similarity with each other and high species-specificity among 7 different species. These results suggest that the heterochromatin of O. hubbsi and O. celebensis consists of various types of repetitive sequence and that the sequences evolved independently and were then amplified site-specifically in each lineage after karyotype reorganization occurred in the ancestral karyotype.

Cytotaxonomic Studies in Four Species of Genus Puntius (Hamilton, 1822) from Central India

The cytotaxonomic analyses of four species of genus Puntius, viz. P. chola, P. conchonius, P. sophore and P. ticto from central India was carried out for the first time. The metaphase chromosomes were prepared from kidney and gill tissues. The diploid chromosome number and karyotype formula (KF) were found to be 50 & 2m + 4sm + 2st + 42t in P. chola; 50 & 14m + 28sm + 8st in P. conchonius; 48 & 4m + 2st + 42t in P. sophore and 50 & 14m + 24sm + 8st + 4t in P. ticto. Based on KF, the fundamental arm number were determined as 56, 92, 52 and 88, respectively, for these species. The karyomorphological features indicated that P. conchonius and P. ticto are closely related and the same holds true for P. chola and P. sophore. The chromosomes of all the four species exhibited constitutive heterochromatic blocks at their centromeric position, as detected by Cbanding technique. Variations in number of NORs were observed with presence of single pair of NORs in P. chola and P. conchonius, whereas in P. sophore and P. ticto multiple NORs were observed. Thus, based on the karyological features it can be hypothesized that P. conchonius and P. ticto may be in advanced stage of karyo-evolution.

Karyological and molecular diversity in three freshwater species of the genusChanna(Teleostei, Perciformes) from India

Genetic variability was assessed among three species of genus Channa, namely C. gachua, C. punctata and C. striata, using karyological tools including karyomorphology, silver nitrate and chromomycin A3 staining of nucleolar organizer regions (NORs) and C-banding. Additionally, sequence variation in partial 18S and divergent domain 1 of 28S ribosomal DNA was utilized for inter-species diversity assessment. Diploid chromosome numbers of 32, 40 and 52 in the three species were observed and the karyotype formula was derived as 18m + 12sm + 2st (fundamental arm number [FN] = 62); 6m + 2sm + 10st + 22t (FN = 48) and 12m + 10sm + 14st + 16t (FN = 86) in C. punctata, C. striata and C. gachua, respectively. Similarly, variations were also observed in number and location of silver and chromomycin A3 stained NORs and C-banding patterns. DNA sequencing generated sizes for 18S of 243, 248, 245 bp and for 28S of 401, 392 and 393 bp in C. gachua, C. punctata and C. striata, respectively. The results indicated that the cytogenetic and molecular markers are useful for the assessment of genetic diversity among the fish species and could provide valuable information for germplasm evaluation and ex situ conservation.

Karyotype Analysis of the New Catfish Mystus ngasep (Siluriformes: Bagridae) from Manipur, India

Karyotypic and cytogenetic characteristics of catfish Mystus ngasep, a new species of bagrid catfish described from the Northeast India, Manipur was studied for the first time by examining 200 metaphase spreads chromosome from the kidney cells of 25 healthy specimens. The diploid chromosome number of this species was 2n=56 and the total fundamental arm number was determined as NF=90. The karyotype consisted of 12 Metacentric (m), 22 Submetacentric (Sm), 8 Subtelocentric (St) and 14 Telocentric (t) chromosomes. The chromosome formula can be represented as 2n= 12m + 22Sm + 8St + 14t. No heteromorphic sex chromosomes were cytologically detected. Chromosome number, formula and karyotype of Mystus ngasep differentiate it from other closely related species. The largest chromosome in this species is a pair of metacentric chromosomes and the present study is the first report on the karyology of this particular species which will pave the way for the future studies on this line of karyology for this genus. Thus, this study is of importance in the analysis of karyotypic evolutionary trends, classification and taxonomy of the genus Mystus and better understanding of the karyotype diversity and chromosome evolution processes.

Detection of interstitial telomeric sequences in the Arctic charr (Salvelinus alpinus) (Teleostei: Salmonidae)

Highly polymorphic Arctic charr ( Salvelinus alpinus Linnaeus, 1758) chromosomes were studied using conventional and molecular methods. The diploid chromosome number in the studied individuals was 2n = 81 or 2n = 82, with a fundamental arm number (NF) = 100. These differences are due to Robertsonian fusions. Interindividual variation in the number and size of DAPI and CMA(3) positively stained chromatin sites was observed in studied specimens. In the case of two individuals, the subtelomeric region of the long arm (q) of the largest acrocentric chromosome (chromosome number 10) was positively stained by CMA(3) fluorochrome. Both primed in situ labelling (PRINS) and fluorescence in situ hybridization (FISH) revealed that this CMA(3)-positive region was flanked by telomeric sequences. Previously, the subterminal position of interstitial telomeric sequences located in the vicinity of the CMA(3)-positive guanine-rich chromatin have been described in two other Salvelinus species, brook trout ( Salvelinus fontinalis ) and lake trout ( Salvelinus namaycush ). Moreover, multichromosomal location and variation in size of CMA(3) bands have been observed in various Salvelinus taxa, including fishes with internally located telomeric sequences. These results suggest that relocation of CMA(3)-positive chromatin segments in these species may be facilitated by flanking interstitial telomeric sequences (ITSs).

Chromosomal differentiation between populations of Clarias gariepinus (Burchell, 1822) from the Göksu Delta and Orontes River (Turkey)

The karyotype of Clarias gariepinus was described by means of G-banding, C-banding, Q-banding, and Ag-NORs (NORs) staining in this study. Samples were collected from 2 regions of Turkey: the Göksu Delta and Orontes River. Although samples from both regions had the same diploid chromosome number and fundamental arm number, (2n = 56, FN = 100), they had remarkable differences in karyotype formula and distribution of rDNA sites, according to silver nitrate staining and G-banding. While the karyotype formula for Orontes River samples was 24m + 10sm + 10st + 12a, the Göksu Delta samples' was 28m + 6sm + 10st + 12a. Comparative analysis showed that there was intraspecific variability in NORs and different NOR numbers in the 2 populations. The study's findings show that the Göksu Delta and Orontes River samples differed from each other.