Elżbieta Smalec

The use of silver nitrate for the identification of spermatozoon structure in selected mammals

Andraszek, K. and Smalec, E. 2011. The use of silver nitrate for the identification of spermatozoon structure in selected mammals. Can. J. Anim. Sci. 91: 239-246. The spermatozoon is one of the most diversified cell types, and the chromatin of the haploid spermatozoon genome is essentially different from that of the somatic cell as regards its chemical composition, structure and function. Although the structure of spermatozoon chromatin has crucial importance for fertilization and embryo development, standard staining techniques are still predominantly used for identifying semen quality and the assessment of spermatozoa is most often limited to detecting irregularities in their morphological structure. The aim of the present research was to evaluate the usefulness of silver nitrate staining for assessing spermatozoon morphology and identifying spermatozoon structure. Spermatozoa isolated from testes and semen were examined. Silver nitrate staining made it possible to identify many significant details of the morphological structure of the spermatozoon and could be successfully employed in sperm morphology assessments.

Assessment of chromosome instability in geese (Anser anser)

Wójcik, E. and Smalec, E. 2012. Assessment of chromosome instability in geese ( Anser anser ). Can. J. Anim. Sci. 92: 49-57. The basic test applied in the research of chromosome instability is the test of sister chromatid exchange (SCE). It makes it possible to identify single-and double-strand DNA damage caused by genotoxic factors and those that disrupt DNA damage repair mechanisms. Fragile sites in chromosomes can be found in all organisms. They are chromosome sites showing susceptibility to breakages and discontinuities in specific conditions of cell culture and also following induction with chemical substances. Chromosome instability of Anser anser geese was assessed in the research, focussing on sister chromatid exchange and the identification of fragile sites. The mean SCE/cell was 4.75±1.00. Most SCEs were identified in the proximal part of the chromosomes. Fragile sites were also identified in the chromosomes during the research. Altogether, 138 breakages were observed in the chromosomes. Apart from identifying chromosome damage, the particular instances of damage were located in the chromosomes.

Structure of the nucleoli in domestic cattle spermatocytes

The work was aimed at determining the number and morphology of nucleoli in the prophase of the first meiotic division in domestic cattle males. The use of AgNO 3 staining, commonly applied in cytogenetics for the identification of nucleolar organiser regions, made it possible to identify nucleoli in first-order spermatocytes. One nucleolus was identified in each analysed cell. Considerable morphological differentiation of the nucleoli during the prophase of the first meiotic division, particularly in leptotene, unobserved in other farm animal species, was noticed. Dark-hued grain-like structures were found within the disintegrating nucleoli, corresponding approximately or exactly to the number of the nucleolar organiser regions in the domestic cattle karyotype. Dark areas were identified in the selected prometaphase chromosomes. Their number corresponded with the number of active NORs defined in the domestic cattle karyotype.

Age-dependent stability of nucleoli and global DNA methylation level in spermatocytes of the domestic horse (Equus caballus)

Abstract: The aim of the study was to determine the number and shape of nucleoli during meiosis in cells of the domestic horse. In addition, the level of global DNA methylation was determined using a quantitative technique for measuring the relative level of DNA methylation, modelled on an immunoenzymatic assay. The research was carried out on stallions belonging to two age groups (2 and 7 yr). In the cells of the 2-yr-old animals, the nucleoli were mainly of a regular shape and no fragmented nucleoli were observed. The cells of the 7-yr-old horses had a small percentage of regularly shaped nucleoli, and nucleoli with a fragmented structure were present. The study provides a basis for further research on epigenetic mechanisms in horses.

Genome size of the European domestic goose (Anser anser domesticus).

This work is aimed at determining the C-DNA contained within the nuclei of different types of cells in the domestic goose Anser anser. Cells from the lungs, skin, pancreas, kidney, spleen, liver, heart, brain, blood, ovary and testicle were analysed. Cells from the blood, ovary and testicle were smeared onto microscopic glasses, whereas slides from the other organs and tissues were prepared using the paraffin technique. DNA content, as visualized by the Feulgen reaction using computerized image analysis, was examined in 200 nuclei of every type of cell. Chicken erythrocytes were used as reference material. Different concentrations of chromatin within cell nuclei were observed, from small, dispersed clods to an entirely filled nucleus surface. It was stated that the average C-DNA content in the domestic European goose amounts to 1.306 ± 0.327 pg, which gives goose DNA a length in base pair of 1.277 × 109 ± 0.320 × 109 bp after adjustment. The correlation between nucleus size and the C-DNA content was posit...

Description of the mallard duck (Anas platyrhynchos) karyotype.

The karyotype of the mallard duck, Anas platyrhynchos, was characterised on the basis of R and C bands. Chromosomal preparations obtained from in vitro blood lymphocyte cultures were RBG- and CBG-stained. The structures of nine and 14 pairs of chromosomes were analysed by the RBG and CBG chromosome banding techniques, respectively. The location of R bands, as well as the size and arrangement of constitutive heterochromatin blocks were determined. Ideograms of R and C banded patterns of the analysed chromosomes were drawn. The morphological makeup of the analysed chromosomes was assessed.

Avian Meiotic Chromosomes as Model Objects in Cytogenetics

The beginning of the new millennium proved critical for life sciences. The team of scientists working on the Human Genome Mapping Project published and made available on the website of Nature a complete set of information on the human genome. Almost simultaneously an independent private company, Celera Genomics, published the results of its study of human DNA sequence in Science. The dream of scientists trying to read the human genome sequence for the last ten years was fulfilled. The end of the related rivalry was the beginning of a new epoch and a new field in genetics – genomics.