Distinctive chromatin in human sperm packages genes for embryo development

Cytology and cytogenetics

The chromosomes of multicellular animals are organized into a series of topologically independent looped domains. This domain organization is critical for the proper utilization and propagation of the genetic information encoded by the chromosome. A special set of architectural elements, called boundaries or insulators, are responsible both for subdividing the chromatin into discrete domains and for determining the topological organization of these domains. Central to the architectural functions of insulators are homologous and heterologous insulator:insulator pairing interactions. The former (pairing between copies of the same insulator) dictates the process of homolog alignment and pairing in trans, while the latter (pairing between different insulators) defines the topology of looped domains in cis. To elucidate the principles governing these architectural functions, we use two insulators, Homie and Nhomie, that flank the Drosophila even skipped locus. We show that homologous insulator interactions in trans, between Homie on one homolog and Homie on the other, or between Nhomie on one homolog and Nhomie on the other, mediate transvection. Critically, these homologous insulator:insulator interactions are orientation-dependent. Consistent with a role in the alignment and pairing of homologs, self-pairing in trans is head-to-head. Head-to-head self-interactions in cis have been reported for other fly insulators, suggesting that this is a general principle of self-pairing. Homie and Nhomie not only pair with themselves, but with each other. Heterologous Homie-Nhomie interactions occur in cis, and we show that they serve to delimit a looped chromosomal domain that contains the even skipped transcription unit and its associated enhancers. The topology of this loop is defined by the heterologous pairing properties of Homie and Nhomie. Instead of being head-to-head, which would generate a circular loop, Homie-Nhomie pairing is head-to-tail. Head-to-tail pairing in cis generates a stem-loop, a configuration much like that observed in classical lampbrush chromosomes. These pairing principles provide a mechanistic underpinning for the observed topologies within and between chromosomes.

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Determinants of Chromosome Architecture: Insulator Pairing in cis and in trans.

Protective effects of Astragalin on spermatogenesis in streptozotocin-induced diabetes in male mice by improving antioxidant activity and inhibiting inflammation

Effect of caponization on performance and quality characteristics of long bones in Polbar chickens.

Sperm morphology and morphometry are important parameters in predicting fertility. Sperm are considered to be normal if the shape and size of the head, midpiece and tail fall within the classification for a given species. It is important to select the appropriate technique for staining the semen of a given species, because, as many authors have pointed out, some methods work well for one species but are not suitable for analysing another. The aim of the study was to assess the morphometric parameters of boar sperm following the use of different staining techniques and to verify the hypothesis that the staining technique affects the morphometric parameters of sperm. The staining method was found to significantly affect the dimensions of the boar sperm head. The semen stained by the SpermBlue technique had the closest morphometric sperm head parameters to those of the unstained sperm, so this technique, rather than the routinely used eosin and gentian complex, should be the leading technique in the evaluation of boar sperm morphometry. Silver nitrate staining reveals the structure of the sperm in the most detail; this method can be considered universal, and can be used independently or to supplement routine diagnostics. As the staining technique should interfere as little as possible with the structure of the sperm, while revealing its morphology in as much detail as possible, it is crucial to establish the natural dimensions of the unstained sperm head before determining the optimal technique and its reference values. The recommended or most commonly-used techniques are not always the best options for the staining and analysis of sperm of a given species.

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The effect of the staining technique on morphological and morphometric parameters of boar sperm

The effect of selected staining techniques on bull sperm morphometry.

Aldona GONTARZ, Dorota BANASZEWSKA, Magdalena GRYZINSKA, Katarzyna ANDRASZEK* Department of Breeding Methods and Poultry and Small Ruminant Breeding, Faculty of Natural Sciences, Siedlce University of Natural Sciences and Humanities, Siedlce, Poland Department of Biological Basis of Animal Production, Faculty of Biology and Animal Science, University of Life Sciences, Lublin, Poland Department of Animal Genetics and Horse Breeding, Faculty of Natural Sciences, Siedlce University of Natural Sciences and Humanities, Siedlce, Poland

https://journals.tubitak.gov.tr/veterinary/issues/vet-16-40-5/vet-40-5-11-1511-6.pdf

Differences in drone sperm morphometry and activity at the beginning and end of the season

The Polish White Improved goat karyotype consists of 29 pairs of acrocentric autosomes, a large acrocentric X chromosome and a metacentric Y chromosome which is the smallest in the karyotype. Staining of chromosomes with AgNO3 solution has revealed active nucleolar organizer regions (NOR) in terminal parts of q arms of pair 2, 3, 4, 5, and 28 chromosomes. Out of the total of 100 analysed cells 736 active NORs have been found, on average 7.4± 0.2 per cell. Active NORs were most frequently observed in pair 2, and 3 chromosomes, most rarely on pair 5 chromosomes. In all the analysed cells 141, satellite associations (SA) were observed, on average 1.4±0.2 per cell. SAs most often occurred in cells with seven active NORs, and least often in cells with three or four nucleolar organizer regions. Most frequently in SAs the presence of pair 2, 3 and 28 chromosomes was observed. On meiotic chromosomes staining with AgNO3 solution revealed two nucleoli stained with different intensity. Both nucleoli in the cell were of similar size.

/pdf/nucleolar-organizer-regions-satellite-associations-and-3pvtz7p9a3.pdf

Nucleolar organizer regions, satellite associations and nucleoli of goat cells ( Capra hircus )

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 mos...

Katarzyna Andraszek

Papers

The effect of the staining technique on morphological and morphometric parameters of boar sperm

The effect of selected staining techniques on bull sperm morphometry.

Differences in drone sperm morphometry and activity at the beginning and end of the season

Nucleolar organizer regions, satellite associations and nucleoli of goat cells ( Capra hircus )

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