Systems Biology in Reproductive Medicine 

About: Systems Biology in Reproductive Medicine is an academic journal published by Informa. The journal publishes majorly in the area(s): Sperm & Male infertility. It has an ISSN identifier of 1939-6368. Over the lifetime, 690 publications have been published receiving 12005 citations. The journal is also known as: Syst Biol Reprod Med & SBiRM.

Adverse Effects of Low Level Heavy Metal Exposure on Male Reproductive Function

Abstract: Lead, cadmium, mercury, and arsenic, often referred to as “heavy metals”, are toxic for wildlife, experimental animals, and humans. While experimental animal and human occupational studies with hig...

Are sperm chromatin and DNA defects relevant in the clinic

Abstract: There has been an increase in the use of sperm DNA and chromatin integrity tests in the evaluation of the infertile man with the hypothesis that these tests may better diagnose infertility and predict reproductive outcomes. This review discusses the etiology of sperm DNA damage, briefly describing the tests of sperm DNA damage, and evaluates the relationship between sperm DNA damage and reproductive outcomes. A systematic review of the literature allows us to conclude that sperm DNA damage is associated with lower natural, intra-uterine insemination (IUI), and in vitro fertilization (IVF) pregnancy rates. Studies to date have not shown a clear association between sperm DNA and chromatin defects and pregnancy outcomes after intra-cytoplasmic sperm injection (ICSI). However, we cannot exclude the possibility that very high levels of DNA damage will impact on ICSI outcomes. In couples undergoing IVF or ICSI, there is evidence to show that sperm DNA damage is associated with an increased risk of pregnancy loss. A limitation of this systematic review and meta-analysis is that it does not address the heterogeneity of the individual study characteristics. Although the clinical utility of tests of sperm DNA damage remains to be firmly established, the data suggest that there is clinical value in testing couples prior to assisted reproductive technologies (ARTs IUI, IVF, and ICSI) and in those couples with recurrent miscarriages. Additional, well-designed prospective studies are needed before testing becomes a routine part of patient care.

Factors Regulating Sperm Capacitation

Abstract: Capacitation is broadly defined as the functional modifications rendering sperm competent to fertilize, encompassing the ability of the sperm to bind the zona pellucida and subsequently undergo the acrosome reaction, hyperactivated motility, and the capacity to fuse with the oocyte. Although discovered in 1951, research over the past 15 years has considerably clarified the mechanisms leading to capacitation. The purpose of this review is to discuss the challenges of studying capacitation and to summarize recent notions regarding its regulation. Of particular interest is an atypical soluble adenylyl cyclase that is stimulated by bicarbonate to activate protein kinase A and drive sperm protein tyrosine phosphorylation. The identities of the phosphorylated sperm-protein substrates and the kinase(s) responsible for their tyrosine phosphorylation have fostered major questions regarding this pathway. Recent investigations, however, have made exciting advances toward resolving these queries. Advanced proteomic approaches have revealed the tyrosine phosphorylated substrates to be implicated in a diverse range of cellular activities. SRC tyrosine kinase is a particularly interesting candidate as the mediator of the protein kinase A-driven sperm protein tyrosine phosphorylation. Future studies are merited to fully characterize additional signaling mediators such as phosphatases and other kinases that may be involved, to elucidate the functional importance of the tyrosine phosphorylation on those particular substrates and to appreciate the differences that may exist among species.

Exposure to Polychlorinated Biphenyls (PCBs) and Male Reproduction

Abstract: Polychlorinated biphenyls (PCBs) are a class of persistent organic pollutants that were widely used in the mid-20th century. Though their production and use was banned by most countries several decades ago, the general population continues to be exposed due to the persistence and bioaccumulation of PCBs. A number of human epidemiological studies have assessed the relationship between environmental PCB exposure and markers of male reproductive health, namely semen quality parameters (sperm concentration, motility, and morphology), sperm DNA integrity (DNA damage or chromatin fragmentation), and circulating reproductive hormone levels. Despite a wide range of study designs and locations, measurement methods, and PCB exposure levels, reports of inverse associations between PCBs and sperm motility have been consistent which may suggest a lack of exposure threshold for a PCB-related effect on sperm motility. Several studies have also reported inverse associations between PCBs and circulating testosterone levels in men, though the specific form of testosterone (i.e. total, bound, or free testosterone) associated with exposure has not been fully consistent between studies. In conclusion, although PCBs are no longer used and can be considered a legacy chemical, concerns regarding altered male fertility in relation to PCBs remain due to the existing human data demonstrating inverse associations with markers of male reproductive function coupled with recent evidence for continued population exposure.

Sperm DNA Tests as Useful Adjuncts to Semen Analysis

Abstract: Male infertility has traditionally been diagnosed by microscopic assessment of concentration, motility and morphology of sperm in the ejaculate. Most laboratories use sperm isolated by various methods such as density gradient centrifugation to enrich for subpopulations of sperm believed to have greater fertilization potential. These tests are essential to provide the fundamental information on which clinicians base their initial diagnosis. However, in the clinical setting, tests with superior prognostic value are needed. Tests showing much promise are those determining sperm DNA integrity, particularly the Comet, TUNEL, and Sperm Chromatin Structure assays. Sperm nuclear DNA fragmentation has been positively correlated with lower fertilization rates in IVF, impaired implantation rates, an increased incidence of abortion and disease in offspring, including childhood cancer. The mitochondrial genome of sperm has also been shown to be a sensitive marker of sperm health. Although the usefulness of these tests is recognized, insufficient resources have been available to develop standardized tests and protocols that could lead to universally accepted clinical thresholds. Associated with the lack of useful prognostic tests is the lack of improvement in assisted conception success rates despite thirty years of worldwide use. International collaborations should be initiated to develop agreed protocols and establish clinical thresholds.