Delivering value from sperm proteomics for fertility

Fertilization of an egg by a spermatozoon sets the stage for mammalian development. Viable sperm are a prerequisite for successful fertilization and beyond. Spermatozoa have a unique cell structure where haploid genomic DNA is located in a tiny cytoplasmic space in the head, mitochondria in the midpiece and then the tail, all enclosed by several layers of membrane. Proteins in sperm play vital roles in motility, capacitation, fertilization, egg activation and embryo development. Molecular defects in these proteins are associated with low fertility or in some cases, infertility. This review will first summarize genesis, molecular anatomy and physiology of spermatozoa, fertilization, embryogenesis and then those proteins playing important roles in various aspects of sperm physiology. © Springer-Verlag 2012

Interrelationships between apoptosis and fertility in bull sperm

Male fertility, the ability of sperm to fertilize and activate the egg and support early embryogenesis, is vital for mammalian reproduction. Despite producing adequate numbers of sperm with normal motility and morphology, some males suffer from low fertility whose molecular mechanisms are not known. The objective was to determine apoptosis in sperm from high and low fertility bulls and its relationship with male fertility. DNA damage, phosphatidylserine (PS) translocation, and expression of proand anti-apoptotic proteins (BAX and BCL-2) in the sperm were determined using TUNEL, Annexin V, and immunoblotting approaches, respectively. Amounts of apoptotic spermatozoa were 2.86 (± 1.31) and 3.00 (± 0.96) in high and low fertility bulls, respectively (P=0.548), and were not correlated with fertility. There was a negative correlation between early necrotic spermatozoa and viable spermatozoa (r = -0.99, P\u3c0.0001). Fertility scores were correlated with live spermatozoa detected by eosin-nigrosin test and necrotic spermatozoa determined via fow cytometry (r = -0.49, P\u3c0.006 and r = -0.266, P\u3c0.0113, respectively). BAX level was higher in low fertile group than high fertile group; however, this difference was not statistically significant due to the variations of bull samples (Bull 1-3 vs. Bull 4-5) in low fertile group (P\u3c0.283). BCL-2 was not detectable in any of the sperm samples. The results shed light onto molecular and cellular underpinnings of male fertility. © 2013 by the Society for Reproduction and Development

RESEARCH Dynamics of microRNAs in bull spermatozoa Open Access

Background: MicroRNAs are small non-coding RNAs that regulate gene expression and thus play important roles in mammalian development. However, the comprehensive lists of microRNAs, as well as, molecular mechanisms by which microRNAs regulate gene expression during gamete and embryo development are poorly defined. The objectives of this study were to determine microRNAs in bull sperm and predict their functions. Methods: To accomplish our objectives we isolated miRNAs from sperm of high and low fertility bulls, conducted microRNA microarray experiments and validated expression of a panel of microRNAs using real time RT-PCR. Bioinformatic approaches were carried out to identify regulated targets. Results: We demonstrated that an abundance of microRNAs were present in bovine spermatozoa, however, only seven were differentially expressed; hsa-aga-3155,-8197,-6727,-11796,-14189,-6125,-13659. The abundance of miRNAs in the spermatozoa and the differential expression in sperm from high vs. low fertility bulls suggests that the miRNAs possibly play important functions in the regulating mechanisms of bovine spermatozoa. Conclusion: Identification of specific microRNAs expressed in spermatozoa of bulls with different fertility phenotypes will help better understand mammalian gametogenesis and early development

Dynamics of microRNAs in bull spermatozoa

Background: MicroRNAs are small non-coding RNAs that regulate gene expression and thus play important roles in mammalian development. However, the comprehensive lists of microRNAs, as well as, molecular mechanisms by which microRNAs regulate gene expression during gamete and embryo development are poorly defined. The objectives of this study were to determine microRNAs in bull sperm and predict their functions.Methods: To accomplish our objectives we isolated miRNAs from sperm of high and low fertility bulls, conducted microRNA microarray experiments and validated expression of a panel of microRNAs using real time RT-PCR. Bioinformatic approaches were carried out to identify regulated targets.Results: We demonstrated that an abundance of microRNAs were present in bovine spermatozoa, however, only seven were differentially expressed; hsa-aga-3155, -8197, -6727, -11796, -14189, -6125, -13659. The abundance of miRNAs in the spermatozoa and the differential expression in sperm from high vs. low fertility bulls suggests that the miRNAs possibly play important functions in the regulating mechanisms of bovine spermatozoa.Conclusion: Identification of specific microRNAs expressed in spermatozoa of bulls with different fertility phenotypes will help better understand mammalian gametogenesis and early development. © 2012 Govindaraju et al.; licensee BioMed Central Ltd

Sperm superoxide dismutase is associated with bull fertility

Decreasing mammalian fertility and sperm quality have created an urgent need to find effective methods to distinguish non-viable from viable fertilising spermatozoa. The aims of the present study were to evaluate expression levels of β-tubulin 2C (TUBB2C), heat shock protein 10 (HSP10), hexokinase 1 (HXK1) and superoxide dismutase 1 (SOD1) in spermatozoa from Holstein bulls with varying fertility using western blotting and to analyse the biological networks of these key sperm proteins using a bioinformatics software (Metacore; Thomson-Reuters, Philadelphia, PA, USA). The rationales behind this study were that the sperm proteins play crucial roles in fertilisation and early embryonic development in mammals and ascertaining the biological networks of the proteins helps us better understand sperm physiology and early mammalian development. The results showed that expression of SOD1 was higher in spermatozoa from high fertility bulls (P\u3c0.05) and that SOD1 is the best protein to diagnose bulls based on the fertility index (P\u3c0.05). Using Metacore analysis, we identified an SOD1 network with pathways and linkages with other relevant molecules. We concluded that SOD1 sperm expression is associated with in vivo bull fertility. The findings are important because they illuminate molecular and cellular determinants of sperm viability and the identified protein markers can be used to determine bull fertility

Endocrine control of bull fertility

Male fertility-the ability to produce viable sperm that are able to support fertilization and oocyte activation and to sustain development during embryogenesis and beyond-is essential for success of mammalian reproduction and development. Production of quality semen depends on the existence of an effective male reproduction system that is consistently able to produce viable gametes. This requires a male with a fertility phenotype that has evolved under the influence of its genetics, environment, and epistasis to a high degree of efficacy. As the sperm from one bull can be used to inseminate tens of thousands of cows, bull fertility has an enormous influence on the efficiency and success of the cattle breeding and reproduction. Even among bulls that produce ample amounts of sperm having apparent normal morphology, some of these animals will still not exhibit high fertility. Despite large investments to study the causes of low fertility as well as research on methods to prevent, diagnose, and treat subpar male fertility, only limited success has been achieved, and the problem remains poorly defined. The objectives of this paper are to review the male reproductive system and the endocrine regulation of male fertility. It will explore the functions of specific hormones regulating male fertility, hormonal control of sperm viability, as well as environmental factors influencing male fertility. The bovine will be the species of focus, but key aspects of male fertility of other mammals (pigs, goats, horses, monkeys and humans) will be included. This review is intended to be a useful source of information for both basic and applied research, as well as for animal production and human andrologists. © 2013 by Nova Science Publishers, Inc. All rights reserved