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Papers by Antonina Natyaganova

Archives of Biological Sciences, 2015

In this paper, we present for the first time data on karyotype analysis of leeches of the genus B... more In this paper, we present for the first time data on karyotype analysis of leeches of the genus Baicalobdella (Piscicolidae) parasitizing Lake Baikal endemic cottoid fishes. Both mitotic and meiotic chromosomes are described. Leech testisacs were processed by a ?shaking-blotting? technique, and chromosomal preparations were stained with water-based fuchsine. Diploid and haploid chromosome sets demonstrated 2n=34 and n=17, respectively, with maximal chromosome length of 1.5-3.0 ?m. Comparative karyotype analysis of two ecological forms of Baicalobdella leeches revealed differences in chromosome numbers and its morphology. Previously studied Baicalobdella torquata (Grube, 1871) parasitizing Baikal amphipods had smaller diploid and haploid sets (2n=32, n=16). In addition to numerical superiority, differing patterns of chromosome size gradation and presence of satellite elements were found in the karyotype of piscine Baicalobdella leeches. This confirms the systematic position of the Ba...

Limnology and Freshwater Biology

For the first time, we present a cytomorphological description of the self-healing (repair) proce... more For the first time, we present a cytomorphological description of the self-healing (repair) process of damaged thalli sites, 'wound healing', in the green filamentous algae, Ulothrix zonata (F. Weber & Mohr) Kützing 1833. In the filaments of this species from Lake Baikal and the Angara (Baikal outflow), Zhilishche (Baikal inflow) and Ida (Angara inflow) rivers, light microscopy methods revealed dome-like and conical protrusions and elongations of transverse cell walls directed into adjacent dead (without protoplast) and defective (with deformed chloroplasts) cells. At the same time, there were mostly patterns where two cells formed protrusions directed into the same damaged filament site between them, i.e. towards each other. The growth of previously unconnected cells towards each other led to their convergence and adjacency. This had two important physiological consequences that ensured the restoration of the filament integrity. The first consequence was the formation of intercellular junctions. The second one was the fusion of the protoplasts and nuclei of the adjacent cells (cell fusion) with the formation of vegetative polyploid cells with increased size. During subsequent divisions of these cells, extended areas emerged with a two-to threefold increase in the diameter of the algal filaments. It was also found that the process of 'wound healing' promoted the development of giant hypnospores. We showed that the H-shaped septa between cells of filamentous algae were not thickenings of the outer walls but the sheaths of the dead cells preserved after this reparation process. Analysis of the 'wound healing' patterns revealed that the Ulothrix cell nuclei did not migrate to the polarized regions of the cells but retained their central position, which testifies to their fixation in the protoplast. We observed sporadic cases of the development of lateral filaments in U. zonata were due to the self-repair of defective cells and their subsequent division during 'wound healing'. A comparison of various cell deformations allowed us to determine the characteristic stages of the 'wound healing' process in U. zonata, which have some similarities and differences with those in marine red filamentous algae. Our study indicates that 'wound healing' is an evolutionarily developed and genetically programmed adaptation that may be widespread in the population of filamentous algae.

"The paradox of taxa sizes" is the situation with unclear causes of differences in spec... more "The paradox of taxa sizes" is the situation with unclear causes of differences in species number at organisms from the same ecosystem. It occurs frequently among Lake Baikal fauna. A typical example are highest crustacea from orders of Amphipoda (more than 300 species) and Isopoda (6 species). Our results of mathematic computer modelling of the karyotypic evolution suggest that the paradox of taxa sizes can be due to different ranges of chromosomal reorganizations which accompanied the evolution of these groups. The ranges of genomic modifications, in turn, are determined by structural peculiarities of the chromosomes, namely by saturation with heterochromatine. Thus, it is possible that "the paradox of taxa sizes", like "the DNA C-value paradox", is due to the phenomenon of redundant («silent») DNA.

Consequences of agrobacterial transformation have resemblance with plant stress response. So agro... more Consequences of agrobacterial transformation have resemblance with plant stress response. So agrobacterial transformation is being considered as a complex multilevel biotic stress factor including reactions on the wounding, contact with pathogen, culturing in vitro and T-DNA insertion. Methodical approaches need developing to distinguish the effects of the transgenesis and associated stresses.

Molecular Ecology, 2003

The six endemic isopod species of Lake Baikal have been regarded as a small species flock with un... more The six endemic isopod species of Lake Baikal have been regarded as a small species flock with uncertain affinities to related asellids. We provide evidence from 16S rRNA sequences for polyphyletic origins of Baikalian Asellidae. One clade of two species is related to the Eurasian genus Asellus. The other clade, Baicalasellus, shows affinities to North American asellids and may have a long evolutionary history within the lake basin. Some speciation events within Baicalasellus clearly have a chromosomal basis. In contrast with numerous taxa exhibiting monophyletic radiations in ancient lakes, the endemic Baikalian isopods arose by multiple invasions and chromosomal mechanisms.

Molecular Ecology, 2003

The six endemic isopod species of Lake Baikal have been regarded as a small species flock with un... more The six endemic isopod species of Lake Baikal have been regarded as a small species flock with uncertain affinities to related asellids. We provide evidence from 16S rRNA sequences for polyphyletic origins of Baikalian Asellidae. One clade of two species is related to the Eurasian genus Asellus. The other clade, Baicalasellus, shows affinities to North American asellids and may have a long evolutionary history within the lake basin. Some speciation events within Baicalasellus clearly have a chromosomal basis. In contrast with numerous taxa exhibiting monophyletic radiations in ancient lakes, the endemic Baikalian isopods arose by multiple invasions and chromosomal mechanisms.

A representative of the Lake Baikal leech fauna was studied karyologically for the first time. Ai... more A representative of the Lake Baikal leech fauna was studied karyologically for the first time. Air-dried cytolo-gical preparations were made from the testisacs of Baicalobdella torquata (Grube, 1871), an endemic species of this lake. The samples were obtained from the population inhabiting the littoral zone of Southern Baikal. Chromosome numbers were determined from both mitotic and meiotic stages of spermatogenesis using "shak-ing-blotting" technique. Diploid and haploid chromosome sets demonstrate 2n=32 and n=16, respectively. This result is similar to that of closely related species Piscicola geometra (Linnaeus, 1758) and confirms systematic position of this species within the family Piscicolidae. Four size groups of chromosomes were detected in B. torquata karyogram, including marker chromosomes. Ring-shaped and cruciform elements were registered within the chromosome set of this leech.

Archives of Biological Sciences, 2015

In this paper, we present for the first time data on karyotype analysis of leeches of the genus B... more In this paper, we present for the first time data on karyotype analysis of leeches of the genus Baicalobdella (Piscicolidae) parasitizing Lake Baikal endemic cottoid fishes. Both mitotic and meiotic chromosomes are described. Leech testisacs were processed by a ?shaking-blotting? technique, and chromosomal preparations were stained with water-based fuchsine. Diploid and haploid chromosome sets demonstrated 2n=34 and n=17, respectively, with maximal chromosome length of 1.5-3.0 ?m. Comparative karyotype analysis of two ecological forms of Baicalobdella leeches revealed differences in chromosome numbers and its morphology. Previously studied Baicalobdella torquata (Grube, 1871) parasitizing Baikal amphipods had smaller diploid and haploid sets (2n=32, n=16). In addition to numerical superiority, differing patterns of chromosome size gradation and presence of satellite elements were found in the karyotype of piscine Baicalobdella leeches. This confirms the systematic position of the Ba...

Limnology and Freshwater Biology

For the first time, we present a cytomorphological description of the self-healing (repair) proce... more For the first time, we present a cytomorphological description of the self-healing (repair) process of damaged thalli sites, 'wound healing', in the green filamentous algae, Ulothrix zonata (F. Weber & Mohr) Kützing 1833. In the filaments of this species from Lake Baikal and the Angara (Baikal outflow), Zhilishche (Baikal inflow) and Ida (Angara inflow) rivers, light microscopy methods revealed dome-like and conical protrusions and elongations of transverse cell walls directed into adjacent dead (without protoplast) and defective (with deformed chloroplasts) cells. At the same time, there were mostly patterns where two cells formed protrusions directed into the same damaged filament site between them, i.e. towards each other. The growth of previously unconnected cells towards each other led to their convergence and adjacency. This had two important physiological consequences that ensured the restoration of the filament integrity. The first consequence was the formation of intercellular junctions. The second one was the fusion of the protoplasts and nuclei of the adjacent cells (cell fusion) with the formation of vegetative polyploid cells with increased size. During subsequent divisions of these cells, extended areas emerged with a two-to threefold increase in the diameter of the algal filaments. It was also found that the process of 'wound healing' promoted the development of giant hypnospores. We showed that the H-shaped septa between cells of filamentous algae were not thickenings of the outer walls but the sheaths of the dead cells preserved after this reparation process. Analysis of the 'wound healing' patterns revealed that the Ulothrix cell nuclei did not migrate to the polarized regions of the cells but retained their central position, which testifies to their fixation in the protoplast. We observed sporadic cases of the development of lateral filaments in U. zonata were due to the self-repair of defective cells and their subsequent division during 'wound healing'. A comparison of various cell deformations allowed us to determine the characteristic stages of the 'wound healing' process in U. zonata, which have some similarities and differences with those in marine red filamentous algae. Our study indicates that 'wound healing' is an evolutionarily developed and genetically programmed adaptation that may be widespread in the population of filamentous algae.

"The paradox of taxa sizes" is the situation with unclear causes of differences in spec... more "The paradox of taxa sizes" is the situation with unclear causes of differences in species number at organisms from the same ecosystem. It occurs frequently among Lake Baikal fauna. A typical example are highest crustacea from orders of Amphipoda (more than 300 species) and Isopoda (6 species). Our results of mathematic computer modelling of the karyotypic evolution suggest that the paradox of taxa sizes can be due to different ranges of chromosomal reorganizations which accompanied the evolution of these groups. The ranges of genomic modifications, in turn, are determined by structural peculiarities of the chromosomes, namely by saturation with heterochromatine. Thus, it is possible that "the paradox of taxa sizes", like "the DNA C-value paradox", is due to the phenomenon of redundant («silent») DNA.

Consequences of agrobacterial transformation have resemblance with plant stress response. So agro... more Consequences of agrobacterial transformation have resemblance with plant stress response. So agrobacterial transformation is being considered as a complex multilevel biotic stress factor including reactions on the wounding, contact with pathogen, culturing in vitro and T-DNA insertion. Methodical approaches need developing to distinguish the effects of the transgenesis and associated stresses.

Molecular Ecology, 2003

The six endemic isopod species of Lake Baikal have been regarded as a small species flock with un... more The six endemic isopod species of Lake Baikal have been regarded as a small species flock with uncertain affinities to related asellids. We provide evidence from 16S rRNA sequences for polyphyletic origins of Baikalian Asellidae. One clade of two species is related to the Eurasian genus Asellus. The other clade, Baicalasellus, shows affinities to North American asellids and may have a long evolutionary history within the lake basin. Some speciation events within Baicalasellus clearly have a chromosomal basis. In contrast with numerous taxa exhibiting monophyletic radiations in ancient lakes, the endemic Baikalian isopods arose by multiple invasions and chromosomal mechanisms.

Molecular Ecology, 2003

The six endemic isopod species of Lake Baikal have been regarded as a small species flock with un... more The six endemic isopod species of Lake Baikal have been regarded as a small species flock with uncertain affinities to related asellids. We provide evidence from 16S rRNA sequences for polyphyletic origins of Baikalian Asellidae. One clade of two species is related to the Eurasian genus Asellus. The other clade, Baicalasellus, shows affinities to North American asellids and may have a long evolutionary history within the lake basin. Some speciation events within Baicalasellus clearly have a chromosomal basis. In contrast with numerous taxa exhibiting monophyletic radiations in ancient lakes, the endemic Baikalian isopods arose by multiple invasions and chromosomal mechanisms.

A representative of the Lake Baikal leech fauna was studied karyologically for the first time. Ai... more A representative of the Lake Baikal leech fauna was studied karyologically for the first time. Air-dried cytolo-gical preparations were made from the testisacs of Baicalobdella torquata (Grube, 1871), an endemic species of this lake. The samples were obtained from the population inhabiting the littoral zone of Southern Baikal. Chromosome numbers were determined from both mitotic and meiotic stages of spermatogenesis using "shak-ing-blotting" technique. Diploid and haploid chromosome sets demonstrate 2n=32 and n=16, respectively. This result is similar to that of closely related species Piscicola geometra (Linnaeus, 1758) and confirms systematic position of this species within the family Piscicolidae. Four size groups of chromosomes were detected in B. torquata karyogram, including marker chromosomes. Ring-shaped and cruciform elements were registered within the chromosome set of this leech.