Chromatin diminution as a tool to study some biological problems.

This work reveals the opportunities to obtain additional information about some biological problems through studying species that possess chromatin diminution. A brief review of the hypothesized biological significance of chromatin diminution is discussed. This article analyzes the biological role of chromatin diminution as it relates to the -value enigma.

Study of chromatin diminution in (Copepoda, Crustacea) by radiobiological methods.

The experimental results show that at doses of 20 Gy and 100 Gy, the development of Lilljeborg, 1901 (Copepoda, Cyclopoida) embryos ceases at the 16-cell stage, without affecting the course of chromatin diminution. A dose of 200 Gy terminated the process of chromatin diminution in some of the embryos. These results support the hypothesis that cytoplasmic factors in the egg play an important role in the process of chromatin diminution.

Thermal tolerance of Cyclops kolensis lilljeborg, 1901 (Copepoda: Cyclopoida) and its relationships with pessimal to optimal performance.

Cyclops kolensis Lilljeborg, 1901 belongs to the Arctic complex of Palaeoarctic species, yet in the past 20 years, its occurrence has extended to the summer months in waterbodies with high water temperatures. This species is considered one of the most active migrants from the northern waterbodies in the Volga reservoir cascade to the Volga delta. Here, we explored the ranges of the preferred and avoidance temperatures of C.

The preferred and avoidance temperatures of Thermocyclops crassus (Fischer, 1853) and their relation to the temperature of optimal, pessimal and normal performance of the species.

The ranges of the preferred and avoided temperatures in representatives of Thermocyclops crassus (Fischer, 1853) were determined by the results of experimental testing in a thermogradient aparatus and comparison of the obtained values with field observations of the optimal, pessimal and tolerated temperature conditions of development of these populations in nature. Copepods were sampled from pond located near Borok, Yaroslavl region, Russia (58o02'57'' N; 38o14'56'' E). The ambient water temperature was 15.

Chromatin Diminution in Cyclops kolensis Lill. (Copepoda, Crustacea) as a Radical Way to Inactivate Redundant Genome in Somatic Cells.

Chromatin diminution (CD) is a phenomenon of programmed DNA elimination which takes place in early embryogenesis in some eukaryotes. The mechanism and biological role of CD remain largely unknown. During CD in the freshwater copepod Cyclops kolensis, the genome of cells of the somatic lineage is reorganized and reduced in size by more than 90% without affecting the genome of germline cells.

Phylogenetic information content of Copepoda ribosomal DNA repeat units: ITS1 and ITS2 impact.

The utility of various regions of the ribosomal repeat unit for phylogenetic analysis was examined in 16 species representing four families, nine genera, and two orders of the subclass Copepoda (Crustacea). Fragments approximately 2000 bp in length containing the ribosomal DNA (rDNA) 18S and 28S gene fragments, the 5.8S gene, and the internal transcribed spacer regions I and II (ITS1 and ITS2) were amplified and analyzed.

Chromatin diminution in Copepoda (Crustacea): pattern, biological role and evolutionary aspects.

This article provides an overview of research on chromatin diminution (CD) in copepods. The phenomenology, mechanisms and biological role of CD are discussed. A model of CD as an alternative means of regulating cell differentiation is presented.

Genetic architecture of the cryptic species complex of Acanthocyclops vernalis (Crustacea: Copepoda). II. Crossbreeding experiments, cytogenetics, and a model of chromosomal evolution.

Collectively, populations of Acanthocyclops vernalis, a species complex of freshwater copepods, are remarkably similar as to morphology and DNA content, despite variability in chromosome number. Reproductive isolation had been reported among some populations, but with each new investigation the species boundaries and factors that may influence them appeared less clear. To clarify the pattern of biological species within this group of populations, we adopted a comprehensive approach and examined patterns of reproductive isolation in populations for which morphology, chromosome number, DNA content, and 18S rDNA sequences are known.