scholarly journals The Drosophila chromosomal protein Mst77F is processed to generate an essential component of mature sperm chromatin

Open Biology ◽  
2016 ◽  
Vol 6 (11) ◽  
pp. 160207 ◽  
Author(s):  
Shuhei Kimura ◽  
Benjamin Loppin
Keyword(s):  
Chromatin Condensation ◽  
Rapid Evolution ◽  
Mature Sperm ◽  
Sperm Chromatin ◽  
Chromosomal Protein ◽  
Sperm Dna ◽  
Cross Links ◽  
Sperm Chromatin Condensation

In most animals, the bulk of sperm DNA is packaged with sperm nuclear basic proteins (SNBPs), a diverse group of highly basic chromosomal proteins notably comprising mammalian protamines. The replacement of histones with SNBPs during spermiogenesis allows sperm DNA to reach an extreme level of compaction, but little is known about how SNBPs actually function in vivo . Mst77F is a Drosophila SNBP with unique DNA condensation properties in vitro , but its role during spermiogenesis remains unclear. Here, we show that Mst77F is required for the compaction of sperm DNA and the production of mature sperm, through its cooperation with protamine-like proteins Mst35Ba/b. We demonstrate that Mst77F is incorporated in spermatid chromatin as a precursor protein, which is subsequently processed through the proteolysis of its N-terminus. The cleavage of Mst77F is very similar to the processing of protamine P2 during human spermiogenesis and notably leaves the cysteine residues in the mature protein intact, suggesting that they participate in the formation of disulfide cross-links. Despite the rapid evolution of SNBPs, sperm chromatin condensation thus involves remarkably convergent mechanisms in distantly related animals.

scholarly journals Hydrozoan sperm-specific H2B histone variants stabilize chromatin and block transcription without enhancing chromatin condensation

2021 ◽  
Author(s):  
Anna Torok ◽  
Martin JG Browne ◽  
Jordina C Vilar ◽  
Indu Patwal ◽  
Timothy Q DuBuc ◽  
...  
Keyword(s):  
Sea Urchins ◽  
Chromatin Condensation ◽  
Ectopic Expression ◽  
Cell Types ◽  
Histone Variants ◽  
Sperm Chromatin ◽  
Chromatin Compaction ◽  
Cycle Arrest

Many animals achieve sperm chromatin compaction and stabilisation during spermatogenesis by replacing canonical histones with sperm nuclear basic proteins (SNBPs) such as protamines. A number of animals including hydrozoan cnidarians and echinoid sea urchins lack protamines and have instead evolved a distinctive family of sperm-specific histone H2Bs (spH2Bs) with extended N-termini rich in SPKK-related motifs. Sperm packaging in echinoids such as sea urchins is regulated by spH2Bs and their sperm is negatively buoyant for fertilization on the sea floor. Hydroid cnidarians also package sperm with spH2Bs but undertake broadcast spawning and their sperm properties are poorly characterised. We show that sperm chromatin from the hydroid Hydractinia possesses higher stability than its somatic equivalent, with reduced accessibility of sperm chromatin to transposase Tn5 integration in vivo and to endonucleases in vitro. However, nuclear dimensions are only moderately reduced in mature Hydractinia sperm compared to other cell types. Ectopic expression of spH2B in the background of H2B knockdown resulted in downregulation of global transcription and cell cycle arrest in embryos without altering their nuclear density. Taken together, spH2B variants containing SPKK-related motifs act to stabilise chromatin and silence transcription in Hydractinia sperm without significant chromatin compaction. This is consistent with a contribution of spH2B to sperm buoyancy as a reproductive adaptation.

scholarly journals Molecular morphology and function of bull spermatozoa linked to histones and associated with fertility

Reproduction ◽  
2013 ◽  
Vol 146 (3) ◽  
pp. 263-272 ◽  
Author(s):  
Rodrigo V de Oliveira ◽  
Sule Dogan ◽  
Lauren E Belser ◽  
Abdullah Kaya ◽  
Einko Topper ◽  
...  
Keyword(s):  
Chromatin Condensation ◽  
Mammalian Species ◽  
Sperm Concentration ◽  
Low Fertility ◽  
Sperm Chromatin ◽  
High Fertility ◽  
Expression Levels ◽  
Molecular Morphology ◽  
Sperm Chromatin Condensation

Sub-par fertility in bulls is influenced by alterations in sperm chromatin, and it might not be solved with increased sperm concentration in artificial insemination. Appropriate histone retention during sperm chromatin condensation plays critical roles in male fertility. The objective of this study was to determine failures of sperm chromatin condensation associated with abnormal persistence or accessibility of histones by aniline blue (ANBL) test, expression levels, and cellular localizations of one variant and two core histones (H3.3, H2B, and H4 respectively) in the spermatozoa of low-fertility (LF) vs high-fertility (HF) bulls. The expression levels and cellular localizations of histones in spermatozoa were studied using immunoblotting, immunocytochemistry, and staining methods. The bioinformatics focused on the sequence identity and evolutionary distance of these proteins among three mammalian species: bovine, mouse, and human. We demonstrated that ANBL staining was different within the LF (1.73 (0.55, 0.19)) and HF (0.67 (0.17, 0.06)) groups (P<0.0001), which was also negatively correlated within vivobull fertility (r=−0.90,P<0.0001). Although these histones were consistently detectable and specifically localized in bull sperm cells, they were not different between the two groups. Except H2B variants, H3.3 and H4 showed 100% identity and were evolutionarily conserved in bulls, mice and humans. The H2B variants were more conserved between bulls and humans, than in mice. In conclusion, we showed that H2B, H3.3, and H4 were detectable in bull spermatozoa and that sperm chromatin condensation status, changed by histone retention, is related to bull fertility.

scholarly journals Sperm chromatin condensation as an in vivo fertility biomarker in bulls: a flow cytometry approach

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Marc Llavanera ◽  
Jordi Ribas-Maynou ◽  
Ariadna Delgado-Bermúdez ◽  
Sandra Recuero ◽  
Rodrigo Muiño ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Sperm Quality ◽  
Chromatin Condensation ◽  
Pearson Correlation ◽  
Correlation Coefficients ◽  
Quality Parameters ◽  
Sperm Chromatin ◽  
Fertility Rates ◽  
Sperm Chromatin Condensation

Abstract Background Genetic selection in cattle has been directed to increase milk production. This, coupled to the fact that the vast majority of bovine artificial inseminations (AI) are performed using cryopreserved sperm, have led to a reduction of fertility rates over the years. Thus, seeking sensitive and specific sperm biomarkers able to predict fertility rates is of vital importance to improve cattle reproductive efficiency. In humans, sperm chromatin condensation evaluated through chromomycin A3 (CMA3) has recently been purported to be a powerful biomarker for sperm functional status and male infertility. The objectives of the present study were: a) to set up a flow cytometry method for simultaneously evaluating chromatin condensation and sperm viability, and b) to test whether this parameter could be used as a predictor of in vivo fertility in bulls. The study included pools of three independent cryopreserved ejaculates per bull from 25 Holstein males. Reproductive outcomes of each sire were determined by non-return rates, which were used to classify bulls into two groups (highly fertile and subfertile). Results Chromatin condensation status of bovine sperm was evaluated through the combination of CMA3 and Yo-Pro-1 staining and flow cytometry. Sperm quality parameters (morphology, viability, total and progressive motility) were also assessed. Pearson correlation coefficients and ROC curves were calculated to assess their capacity to predict in vivo fertility. Sperm morphology, viability and total motility presented an area under the ROC curve (AUC) of 0.54, 0.64 and 0.68, respectively (P > 0.05), and thus were not able to discriminate between fertile and subfertile individuals. Alternatively, while the percentage of progressively motile sperm showed a significant predictive value, with an AUC of 0.73 (P = 0.05), CMA3/Yo-Pro-1 staining even depicted superior results for the prediction of in vivo fertility in bulls. Specifically, the percentage of viable sperm with poor chromatin condensation showed better accuracy and precision to predict in vivo fertility, with an AUC of 0.78 (P = 0.02). Conclusions Chromatin condensation evaluated through CMA3/Yo-Pro-1 and flow cytometry is defined here as a more powerful tool than conventional sperm parameters to predict bull in vivo fertility, with a potential ability to maximising the efficiency of dairy breeding industry.

scholarly journals Prolactin and Male Fertility: The Long and Short Feedback Regulation

2009 ◽  
Vol 2009 ◽  
pp. 1-13 ◽  
Author(s):  
M. K. Gill-Sharma
Keyword(s):  
Chromatin Condensation ◽  
Feedback Regulation ◽  
Pituitary Hormones ◽  
Feedback Mechanism ◽  
Reproductive Hormones ◽  
Male Rats ◽  
Normal Men

In the last 20 years, a pituitary-hypothalamus tissue culture system with intact neural and portal connections has been developed in our lab and used to understand the feedback mechanisms that regulate the secretions of adenohypophyseal hormones and fertility of male rats. In the last decade, several in vivo rat models have also been developed in our lab with a view to substantiate the in vitro findings, in order to delineate the role of pituitary hormones in the regulation of fertility of male rats. These studies have relied on both surgical and pharmacological interventions to modulate the secretions of gonadotropins and testosterone. The interrelationship between the circadian release of reproductive hormones has also been ascertained in normal men. Our studies suggest that testosterone regulates the secretion of prolactin through a long feedback mechanism, which appears to have been conserved from rats to humans. These studies have filled in a major lacuna pertaining to the role of prolactin in male reproductive physiology by demonstrating the interdependence between testosterone and prolactin. Systemic levels of prolactin play a deterministic role in the mechanism of chromatin condensation during spermiogenesis.

scholarly journals DNA methylation specifies chromosomal localization of MeCP2.

1996 ◽  
Vol 16 (1) ◽  
pp. 414-421 ◽  
Author(s):  
X Nan ◽  
P Tate ◽  
E Li ◽  
A Bird
Keyword(s):  
Dna Methylation ◽  
Cultured Cells ◽  
Centromeric Heterochromatin ◽  
Intact Protein ◽  
Chromosomal Protein ◽  
Mouse Cells ◽  
Low Levels ◽  
Mutant Cells

MeCP2 is a chromosomal protein that is concentrated in the centromeric heterochromatin of mouse cells. In vitro, the protein binds preferentially to DNA containing a single symmetrically methylated CpG. To find out whether the heterochromatic localization of MeCP2 depended on DNA methylation, we transiently expressed MeCP2-LacZ fusion proteins in cultured cells. Intact protein was targeted to heterochromatin in wild-type cells but was inefficiently localized in mutant cells with low levels of genomic DNA methylation. Deletions within MeCP2 showed that localization to heterochromatin required the 85-amino-acid methyl-CpG binding domain but not the remainder of the protein. Thus MeCP2 is a methyl-CpG-binding protein in vivo and is likely to be a major mediator of downstream consequences of DNA methylation.

scholarly journals Modulations of SIR-nucleosome interactions of reconstructed yeast silent pre-heterochromatin by O-acetyl-ADP-ribose and magnesium

2017 ◽  
Vol 28 (3) ◽  
pp. 381-386 ◽  
Author(s):  
Shu-Yun Tung ◽  
Sue-Hong Wang ◽  
Sue-Ping Lee ◽  
Shu-Ping Tsai ◽  
Hsiao-Hsuian Shen ◽  
...  
Keyword(s):  
Gene Silencing ◽  
Chromatin Condensation ◽  
Epigenetic Inheritance ◽  
Assembly System ◽  
Sir Proteins ◽  
Epigenetic Gene Silencing ◽  
In Vitro Assembly ◽  
The Individual

Yeast silent heterochromatin provides an excellent model with which to study epigenetic inheritance. Previously we developed an in vitro assembly system to demonstrate the formation of filament structures with requirements that mirror yeast epigenetic gene silencing in vivo. However, the properties of these filaments were not investigated in detail. Here we show that the assembly system requires Sir2, Sir3, Sir4, nucleosomes, and O-acetyl-ADP-ribose. We also demonstrate that all Sir proteins and nucleosomes are components of these filaments to prove that they are SIR-nucleosome filaments. Furthermore, we show that the individual localization patterns of Sir proteins on the SIR-nucleosome filament reflect those patterns on telomeres in vivo. In addition, we reveal that magnesium exists in the SIR-nucleosome filament, with a role similar to that for chromatin condensation. These results suggest that a small number of proteins and molecules are sufficient to mediate the formation of a minimal yeast silent pre-heterochromatin in vitro.

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