Biomedical subjects

I I Kiknadze

Publications and source records attributed to I I Kiknadze.

At least 19 recordsLinked to original sources

PubMed2006

[The chromosomal polymorphism and divergence of populations in Chironomus nuditarsis Str. (Diptera, Chironomidae)].

The karyotype structure and chromosomal polymorphisms were investigated in 6 natural and 2 laboratory populations of Chironomus nuditarsis from Europe and Asia. The pool of rearranged polytene chromosome banding sequences of this species was determined that includes 16 inversion banding sequences and sequences with giant DNA-knobs (ndtG1k, ndtG2k). Obvious differences were demonstrated in the level of chromosomal polymorphism between European and Asian (Siberian) populations: the former were highly polymorphic, while the latter were practically monomorphic. It was suggested to consider the Siberian populations as marginal one. Cytogenetic distances between populations of C. nuditarsis as well between C. nuditarsis and the related species C. plumosus were estimated. The data obtained show that chromosomal rearrangements play a very important role in cytogenetic divergence of populations.

Animals↗

PubMed2005

[Divergence of the polytene chromosome banding sequences as a reflection of evolutionary rearrangements of the genome linear structure].

Banding sequences of five chromosomal arms (A, C, D, E, and F), accounting for about 70% of the total genome size in 63 Chironomus species, were used as phylogenetic markers to analyze divergence patterns of the linear genome structure during the evolution. The number of chromosomal breakpoints between the pairs of banding sequences compared served as a measure of divergence. It was demonstrated that the greater the divergence between the species compared, the higher the number of chromosomal breakpoints and the smaller the size of the conserved chromosomal regions. A banding sequences comparison in sibling species demonstrated a lower number of chromosomal breakpoints; the breakpoint number was maximum in a comparison of the banding sequences in the subgenera Chironomus and Camptochironomus. The use of the number of chromosomal breakpoints as a divergence measure provided establishment of phylogenetic relationships between 63 Chironomus species and discrimination of sibling species groups and cytocomplexes on a phylogenetic tree.

Animals↗

PubMed2005

[Variation and divergence of multilocus genome markers in the species of the genus Chironomus (Diptera, Chironomidae)].

Variation and divergence patterns of the multilocus genome markers in twelve Chironomus species belonging to the plumosus and piger sibling-species groups were examined by use of polymerase chain reaction with random primers (RAPD method). The chironomid species showed high levels of the RAPD markers polymorphism. The genetic distances (GD) were determined between the species within the group of closely related species, as well as between the species from different groups. The estimates obtained characterized the divergence levels between the sibling species (GD = 0.739) and morphologically distinct species (GD = 0.935). Comparison of the variation and divergence levels of the RAPD markers with those for the other genome markers, namely, the enzyme-coding genes and chromosomes (gene linkage groups) have demonstrated different divergence rates for different genome components during speciation of Chironimids.

Animals↗

PubMed2005

[Karyotype structure in species of Propsilocerus genus (Diptera, Chironomidae)].

Karyotype structure and polytene chromosome banding patterns were studied in two Orthocladiinae siblings--Propsilocerus akamusi (China) and Propsilocerus jacuticus (Russia). Both species have haploid number of chromosome typical for Orthocladiinae (n = 3). An unusual structure of centromeric regions was observed in all three chromosomes of karyotypes in both species. Photomaps of polytene chromosomes are presented. A comparison of karyotypes of P. akamusi and Propsilocerus jacuticus revealed a high level of homology in their banding sequences, however, the presence of fixed paracentric inversions in chromosomal arms IR, IIR, IIIR of Propsilocerus jacuticus has shown a clear-cut phylogenetic divergence. No chromosomal polymorphism was found in both species.

Animals↗

PubMed2003

[Molecular-cytogenetic characteristics of B-chromosomes in chironomid (Diptera, Chironomidae)].

Morphological and molecular study of B-chromosomes of three Chironomus species (siblings Ch. borokensis and Ch. phumosus from plumosus group, and Ch. heterodentatus from obtusidens group) was carried out. Morphological similarity of B-chromosome banding pattern and telomer-centromeric region banding pattern of chromosome IV in Ch. borokensis was shown. Polytene B-chromosomes of Ch. borokensis and Ch. heterodentatus were microdissected, and their DNA was amplified using degenerate oligonucleotide primer polymerase chain reaction. Comparative analysis of the localization of homologous B-chromosome DNA sequences of A- and B-polytene chromosomes was made using in situ fluorescence hybridization. It has been shown that B-chromosomes in the studied species are composed mainly of repetitive DNA sequences homologous to sequences of centromeric and telomeric DNA of A-chromosomes, and also these of the mobile element NLRCthl. The B-chromosome DNA, homologous to sequences of DNA mobile element, was scattered on A-chromosomes (more than 100 sites). No ribosomal DNA repeats were identified in B-chromosome. Heterologous FISH of B-chromosome DNA to polytene A-chromosomes of Ch. thummi, a species lacking B-chromosomes, enabled us to reveal the presence of numerous sites homologous to DNA of B-chromosomes. These are mainly mobile element sites. An origin of B-chromosomes and peculiarities of their organization in chironomids are discussed.

Animals↗

PubMed2002

[The functional morphology of polytene chromosomes in the midge Chironomus pilicornis F. from the permafrost zone reservoirs].

The karyotype and chromosomal polymorphism of Chironomus pilicornis from the reservoirs of Yakutian permafrost zone are described. In the Yakutian populations, of 10 inversion sequences 11 genotypical combinations of these were registered. The level of inversion heterozygosity is 50-70%, but in several populations it makes only 11-29%. In comparison with the Scandinavian populations, significant functional modifications of chromosomal morphology were found. They are associated with the increase in centromeric heterochromatin amount, facultative chromocentre formation, and the appearance of numerous B-chromosomes and nucleoli, including the facultative ones. A possible adaptive significance of such functional modifications conditioned by climate peculiarities is discussed.

Adaptation, Biological↗

PubMed2002

[Evidence of species specific pericentric inversion in the karyotype of the midge Chironomus balatonicus].

Pericentric inversions do not play any important role in chromosomal rearrangements in the karyotype evolution of the genus Chironomus. However, a unique case of the fixed pericentric inversion was discovered in chromosome 2 of Chironomus balatonicus--one of the members of plumosus-species group (Kikhadze et al., 1996a; Golygina et al., 1996). According to morphological criteria, a centromere band on chromosome 2 changed its position in Ch. balatonicus. The cloned H3-SauDNA, specific for centromeres in plumosus group, was in situ hybridized with Ch. balatonicus polytene chromosomes, and thus a real change in the centromere position was proved to be a result of pericentric inversion. This was also confirmed after differential C-staining.

Animals↗

PubMed2001

Polyploidization in the trophoblast and uterine glandular epithelium of the endotheliochorial placenta of silver fox (Vulpes fulvus Desm.), as revealed by the DNA content.

Dynamics of genome multiplication during establishment of interrelations between trophoblast and glandular epithelium of the endometrium has been studied in the course of formation of placenta in the silver fox. During formation of the placenta, penetration of the trophoblast into the zone of the endometrial glandular epithelium and of endometrial blood vessels into the zone of expanding trophoblast occurs. The trophoblast, which gradually replaces epithelium and a part of the stroma of the endometrium, closely adjoins endometrial vessels but does not disrupt them, thereby the endotheliochorial placenta is formed. Cytophotometric measurements of the DNA content in trophoblast nuclei have shown that most of them are polyploid: predominantly 4-64c, occasionally 128c and 256c. Polyploidy of the trophoblast may be a consequence of various types of polyploidizing mitoses. Cytophotometric measurements of the DNA content in mitotic figures have revealed the presence of mitoses of diploid cells, i.e. with the DNA amount of 4c (2n), and polyploid cells, i.e. 8c (4n), and 16c (8n), therefore trophoblast cells in the silver fox placenta are able to enter mitosis up to the octaploid level. Higher degrees of polyploidy in the trophoblast cells seem to be achieved by endoreduplication. Polyploidization of the uterine glandular epithelial cells during placentation in the silver fox occurs until the level of 8c. Thus, the tissue-specific response of the uterus to the implanting embryo consists of active proliferation and polyploidization of the glandular epithelium, which may compensate formation of prominent population of decidual cells (i.e., connective tissue cells). In the endotheliochorial placenta of the silver fox the regularity is confirmed that cells of both maternal and fetal origin are, as a rule, polyploid in sites of their contact in placenta, which may be of protective significance in the contact of allogenic organisms.

Animals↗

PubMed2001

[Karyofund of Chironomus plumosus (Diptera, Chronomidae) in the Palearctic region].

Quantitative and qualitative analyses of chromosomal polymorphism in 38 Palearctic populations of Chironomus plumosus were made. It was shown that most of the populations studied were highly polymorphic: in average 63.2 +/- 4.0% of larvae were heterozygous for inversions with 0.95 + 0.08 heterozygous inversion per larvae. Polymorphism on the size of centromeric heterochromatin and the presence of B-chromosomes were observed in many populations studied. The karyofund of Ch. plumosus in Palearctic was estimated. In total 35 banding sequences were found in Palearctic Ch. plumosus. Fifteen banding seguences have been described for the first time. On mapping the used banding sequences, we employed the conventions of Keyl (Keyl, 1962; Devai et al., 1989) and Maximova (Maximova, 1976; Shobanov, 1994a) for arms A, C, D, E and F, and the conventions of Maximova for arms B and G.

Animals↗

PubMed2000

Intercontinental karyotypic differentiation of Chironomus entis Shobanov, a Holarctic member of the C. plumosus group (Diptera, Chironomidae).

Analysis of banding sequences of polytene chromosomes in Palearctic (Russian) and Nearctic (North American) Chironomus entis shows strong karyotype divergence between populations on the two continents. Four out of seven chromosomal arms in the North American C. entis karyotype are characterized by sequences found only in the Nearctic. In total, 44 banding sequences are now known for this species across the Holarctic, including 22 exclusively Palearctic, 6 Holarctic, and 16 exclusively Nearctic sequences. The degree of cytogenetic differentiation between Palearctic and Nearctic C. entis populations is an order of magnitude greater than differentiation among populations within either continent, but is only one third as great as the cytogenetic distance between the sibling species C. entis and C. plumosus. C. entis is the only sibling species of C. plumosus uncovered during cytological identification of Chironomus species from more than 50 North American lakes, indicating that the plumosus sibling-species group is much smaller in the Nearctic than in the Palearctic, where a dozen sibling species are known. Cytogenetic distance values calculated between Nearctic and Palearctic representatives of both C. entis and its sibling species C. plumosus are similar, but result from different patterns of karyotype divergence. New World C. entis is distinguished from Old World populations by the 16 uniquely Nearctic sequences, four of which occur in the homozygous state. In contrast, North American C. plumosus has fewer uniquely Nearctic sequences, and only one that occurs as a homozygote. However, four chromosomal arms in C. plumosus that are polymorphic in the Palearctic show fixation, or near fixation, of Holarctic sequences in the Nearctic C. plumosus karyotype. Thus, both the fixation of Holarctic sequences, and the occurrence or fixation of distinctly Nearctic sequences, contribute significantly to karyotype divergence. Patterns of karyotype divergence in Palearctic and Nearctic populations of different Holarctic chironomid species are discussed relative to intercontinental cytogenetic differentiation in other dipterans.

Animals↗

PubMed2000

[Divergence of karyofunds in sibling species of the plumosus group (Diptera: Chironomidae)].

Cytogenetic differentiation of eight sibling species of the plumosus group was examined. The karyofunds of these sibling species were shown to diverge incompletely. In each species karyofund, the banding sequences homologous to those of the remaining species of this group were revealed. The number of banding sequences that displayed interspecific homology varied from 3 to 13 per species karyofund. In a species karyotype, the homologous sequences were localized to chromosome arms 1-6. Both similar and contrasting frequencies of homologous banding sequences were observed in karyofunds of different sibling species. The average cytogenetic distance between sibling species of the plumosus group was 2.618 +/- 0.400. The presence of species-specific banding sequences, the absence of homologous banding sequences in some chromosome arms of the karyotype, and different frequencies of the homologous banding sequences determined the cytogenetic divergence of the sibling species.

Animals↗

PubMed2000

[Karyotype of the midge Chironomus heterodentatus Konstantinov from the group Obtusidens (Diptera, Chironomidae)].

The karyotype of Chironomus heterodentatus, belonging to the obtusidens-group described by Konstantinov from the Volga in 1956, was studied in detail. Combinations of chromosomal arms are AB, CD, EF and G (cytocomplex thummi). The Ch. heterodentatus karyotype cleary differs from those of other members of the obtusidens-group with a species-specific banding pattern in arms A, B, C and D. Chromosomal polymorphism on homo- and heterozygous inversions was found in arms, A, B, D, E and G. 19 inversion banding sequences and their 27 genotypic combinations have been recorded. The shortest arm G is highly polymorphic. Heterozygotes on the Balbiani ring activity were found in arm G along with homo- and heterozygotes on inversions. B-chromosomes with a frequency equal to 2.7-25.0% were recorded in some Volga populations.

Animals↗

PubMed2000

[Genome multiplication in the trophoblasts and glandular epithelium of endometrium during embryo implantation and placentation of silver fox].

Dynamics of genome multiplication during establishment of interrelations between the trophoblast and the glandular epithelium of endometrium was studied in the course of placenta formation in the silver fox. Endometrium response on the embryo implantation exhibits some features of inflammation. In the course of placenta formation the trophoblast gains access to the endometrial glandular epithelium zone, while the endometrial blood vessels grow the other way into the expanding trophoblast zone. The trophoblast gradually replaces the whole epithelium and part of the stroma of the endometrium, closely adjoining the endometrial vessels but not disrupting them. Cytophometric DNA measurements in the trophoblast nuclei have shown that most of the nuclei are polyploid: predominantly 4c-64c, occasionally 128c and 256c. Polyploidy of the trophoblast may result from various types of polyploidizing mitoses. Cytophotometric DNA measurements in mitotic figures have revealed mitoses with DNA amounts equal to 4c (2n), 8c (4n), and 16c (8n), which indicates that trophoblast cells in the silver fox placenta are able to enter mitosis prior to the octaploid level. Higher degrees of polyploidy in the trophoblast cells may be achieved presumably by endoreduplication. In the silver fox polyploidization of uterine grandular epithelial cells during placentation occurs until the level of 8c. Thus, the tissue-specific response of the uterus to the implanting embryo is an active proliferation and polyploidization of the glandular epithelium, rather than formation of a population of polyploid decidual cells (i.e. connective tissue cells). Using the silver fox endotheliochorial placenta as an example, a regularity has been confirmed that cells of both maternal and fetal origin are polyploid in sites of their contact in placenta, which might be of protective significance in the contact of allogenic organisms.

Animals↗

PubMed1994

Centromeric heterochromatin and satellite DNA in the Chironomus plumosus species group.

Species of the Chironomus plumosus group display significant differences in their amount of centromeric heterochromatin. A tandem-repetitive satellite-like DNA has been isolated from C. plumosus. This DNA accounts for a major part of the centromeric heterochromatin. The DNA element has a Sau3AI restriction site ("Sau elements") and a monomer length of 165 or 166 bp. It is A-T rich (73%) and reveals a moderate DNA curvature, as shown by gel migration and computer analysis. The chromosomal localization and genomic organization of Sau elements were studied in 24 Chironomus species by in situ hybridization and (or) Southern analysis. The DNA is predominantly located in the centromeric regions of nine species, six from the plumosus group and three others. In some cases, inter- and intra-specific differences in the size of the centromeric heterochromatin seem to correlate with the strength of Sau element hybridization signals. Few species contain Sau repeats outside of the centromeres (C. borokensis, C. plumosus). Additionally, Sau elements are revealed to be present in ectopic threads between centromeres, and in B chromosomes found in C. borokensis and C. annularius.

Animals↗

PubMed1994

[Polyploid mitoses in mink trophoblast cells].

Mitotic figures in the mink placental trophoblasts have been observed under the light microscope using actions and air-dried preparations. The tetra- and octaploid metaphase chromosome spreads were found on Giemsa-stained air-dried preparations. A high percentage (up to 80%) of abnormal metaphases, including k-mitoses as well as a portion of restitution anaphases, was revealed on sections of the placental trophoblast suggesting a possible block of mitosis at the meta- and anaphase. Therefore, it is very likely that genome multiplication in a portion of placental trophoblast cells in mink involves block of mitoses at meta- and anaphase followed by restitution. The chromosomal arrangement on metaphase spreads in part of cells showed a degree of separation of the whole di- and tetraploid chromosome sets within tetraploid and octaploid chromosome plates. Several spreads exhibited some allocycly of diploid chromosome sets inside the polyploid metaphases. It is not inconceivable that such an arrangement may reflect some autonomy of low-ploidy chromosome sets within the polyploid trophoblast cells in mink.

Animals↗

PubMed1992

[Polyploidy and polyteny in the trophoblast cells of the mink].

According to cytophotometry, trophoblast cells in the mink placenta are both diploid and polyploid, the ploidy level ranging from 2c to 64c. A great number of mink trophoblast cells were seen to divide mitotically. In addition to the ordinary mitotic figures, polyploid mitoses as well as abnormal mitotic figures were observed. Non-classic polytene chromosomes, peculiar to the mammalian trophoblast, appeared in the mink trophoblast cells to have the highest ploidy. A relatively low ploidy degree is due, probably, to a lesser invasive activity of the mink trophoblast cells as compared to the rodent giant trophoblast cells.

Animals↗

PubMed1991

MEC: a transposable element from Chironomus thummi (diptera).

Two genomic clones, pC1.2 and p20D (containing inserts of 2.0 and 1.6 kb, respectively) were isolated from the A2b region to polytene chromosome IV of Chironomus thummi thummi salivary gland cells. Upon in situ hybridization to polytene chromosomes of C. thummi thummi and C. thummi piger, p20D DNA hybridized mainly over the A2b region of chromosome IV, whereas pC1.2 DNA hybridized to at least 90 sites distributed over all the chromosomes. A partial nucleotide sequence analysis showed that these clones were very similar and allowed the detection of a 596 bp insert in the pC1.2 clone. This insert possesses all of the essential features of a Class II transposable element and was called MEC. It carries a nearly perfect 107 bp terminal inverted repeat containing one mismatch and is flanked by a 5 bp direct repeat. The 372 bp central region contains a short open reading frame with a coding capacity of 58 amino acids.

Amino Acid Sequence↗

PubMed1990

A tissue-specific puff (Balbiani ring a) in Chironomus thummi may contain a gene encoding a 67-kDa protein which exhibits non-tissue-specific expression.

A 2.3-kb genomic clone has been isolated from the region where the tissue-specific puff, Balbiani ring a (BRa), is found on chromosome IV of the special lobe of Chironomus thummi salivary gland cells. The clone was characterized by nucleotide sequence analysis. Two clusters of direct tandem repeats were identified, as well as large and small open reading frames (ORFs). The large ORF was fused to an Escherichia coli lacZ gene. Antibodies against the beta-galactosidase/ORF fusion protein reacted selectively on Western blots with a 67-kDa protein. Western-blot analysis and immunoelectron microscopy showed that this protein was distributed in the cells of all larval tissues examined. We concluded that BRa, a tissue-specific puff, whose activity correlates with the synthesis of 160-kDa secretory protein [Kolesnikov et al., Chromosoma 83 (1981) 661-677], may also contain a gene which is not expressed in a tissue-specific manner.

Amino Acid Sequence↗