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article imageEssential Science: Why the microbiome of seminal fluid is important

By Tim Sandle     Apr 4, 2016 in Science
New research discusses the microbiome of seminal fluid. Although focused on animals, the research could lead to a new area of medicine where the microorganisms in seminal fluid could be used to assess male health.
The microbiome is a multifaceted ecosystem. The term describes the totality of microorganisms, their genetic elements, and relationship with other cells within a given niche. Here it is possible, in relation to the human body, to discuss the microbiome of the skin or of the gut, as examples. These organisms are "the ecological communities of commensal, symbiotic, and pathogenic microorganisms that literally share our body space."
Understanding of the microbiome has been advanced by Human Microbiome Project (HMP), which began in 2008 as a United States National Institutes of Health initiative. Work relating to the project continues, especially in areas relating to health and disease. As an example of the research, evidence indicates that microbiome itself can also influence the human physiological response to pharmaceutical products. This has opened up a new area of personalized medicine, where medications are being tailored for particular patients (this was the subject of a recent Digital Journal Essential Science feature.)
Knowing precisely the microbes present in a wound could greatly aid in the prevention and treatment of infections. This is especially important when dealing with the severe injuries that soldiers can suffer in combat.
New research has examined what remains a poorly examined microbiome — the seminal vesicles. These are the glands that produce the fluid that eventually becomes semen. Initially work has focused on mice.
The work is interesting because it is the first comprehensive review of the microorganisms found in semen. Earlier studies have cataloged the bacteria present in human semen (and, again of interest, some of these microbes are similar to those identified in mice.) However, the human samples are not sufficiently comprehensive of the full range of microorganisms. This is because the human derived samples had been passed through the ureter (tubes made of smooth muscle fibers that propel urine from the kidneys to the urinary bladder .) Coupled with this, contrary to some opinion, urine is not sterile.
The consequence of this meant it was not clear where within the body the bacteria isolated came from within the complex urogenital system.
To find out more, researchers withdrew seminal vesicles together with fluid directly from male mice. The microorganisms contained within the fluid were sequenced, examining a region of the microbial genome called 16S rRNA. Analysis was undertaken using a device called the Illumina MiSeq. The 16S rRNA gene acts as an effective molecular marker for identification of various bacterial species because it is highly conserved between different species of bacteria, meaning it does not change over time, is not influenced by environmental factors, and it is large enough for informatics purposes.
Through the analysis, researchers identified several groups of bacteria, notably: Proteobacteria, Actinobacteria, Fusobacteria, Flavobacteria, and Acidobacteria. These organisms differed from those recovered in fecal samples from the mice.
So far, matters of microbiological interest. But what are the implications? The researchers had the aim of seeking to understand if a father’s seminal fluid microbiome could contribute to the health or disease of his offspring.
Through this review it was found that wild-type mice (bred to represent mice as found in nature rather than laboratory type mice) had far greater quantities of a certain bacterium called Propionibacterium acnes compared with laboratory mice. This bacterium may be familiar to some readers, since P. acnes is responsible for acne. In addition to this, the bacterium has been connected to chronic prostatitis, which can lead to prostate cancer.
Acne is most common during adolescence  affecting more than 85% of teenagers.
Acne is most common during adolescence, affecting more than 85% of teenagers.
wikipedia (cc)
Chronic prostatitis causes long-term pain and urinary symptoms. It involves the prostate gland or other parts of a man's lower urinary tract or genital area. There is a bacterial form and a non-bacterial type. Bacterial forms can arise from sexually transmitted infections. With the one bacterium of concern, P. acnes secretes cytotoxic chemicals and enzymes designed to degrade body tissues, which has been associated with cancer of the prostate. One reason is because the seminal vesicles are located next to the prostate in the body.
Based on the success with mice, the researchers aim to carry out a similar exercise with people. It is hoped that if P. acnes is present in human semen then it could function as a potential biomarker for prostate disease. To do this, scientists would need reference ranges of the bacterium for healthy men and men with prostatitis.
Another area that the researchers want to explore is whether the sharing the seminal fluid microbiome (from the male to the female when mating) affects offspring development. To show this, the research group will return to the mouse study. Here, according to the science site Bioscience Techniques, the aim is to inject antibiotics directly into the seminal vesicles of males and then carry out several metabolic and behavioral tests on the offspring.
The study was led by Dr. Cheryl Rosenfeld from the University of Missouri College of Veterinary Medicine. The research is published in the journal Scientific Reports. The research is titled "Discovery of a Novel Seminal Fluid Microbiome and Influence of Estrogen Receptor Alpha Genetic Status."
This article is one of Digital Journal's Essential Science columns. Each week we explore a topical and important scientific issue. Last week we examined how scientists had created a semi-synthetic, functioning bacterium in the lab that has fewer than 500 genes. The importance of "500" is that no bacterium in nature has less than 500 genes. The previous week we looked at new a theory that Jupiter had once bumped other proto-planets out of the way in its journey away from the Sun, billions of years ago.
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