Navigation Links
Fitness for toad sperm: The secret is to mate frequently

Fertility tests frequently reveal that males have problems with the quality of their sperm. The problems often relate to sperm senescence, which is a reduction in quality with age. Sperm senescence can arise either before or after the DNA in the sperm cells is produced by a process known as meiosis. So-called "pre-meiotic" senescence results from accumulated damage in the germline cells with increasing age and results in older males having sperm of lower quality. Post-meiotic senescence occurs after the sperm cells have been produced, either during storage of sperm by the male or after ejaculation and before they fertilize the eggs.

There is previous evidence that various kinds of sperm senescence occur in insects, in some domestic animals (birds and mammals) and even in humans but the studies have generally been carried out under fairly artificial conditions and so it is not clear how they relate to wild animals or to the general human population. These objections have been overcome in the latest work of Attila Hettyey and colleagues at the Konrad Lorenz Institute of Ethology, University of Veterinary Medicine, Vienna (Vetmeduni), together with Balzs Vgi in Budapest, Hungary, where Hettyey himself is now working.

The researchers investigated the common toad, an interesting model system as it is known to produce all its sperm before the start of the breeding season. They found that male toads that re-entered hibernation at the start of the breeding season, i.e. that lowered their metabolic rates after producing sperm, stored sperm of significantly higher motility than males kept under pseudo-natural conditions without females throughout the entire breeding season. The result means that slowing the normal rate of general physiological processes reduced the normal rate of sperm ageing within the toad's testicles. This constitutes the first evidence for post-meiotic intra-testicular sperm senescence in a wild vertebrate. A further surprising result was that in males kept under pseudo-natural conditions, sperm motility was related to the number of matings a male achieved, with the presence of females or the occurrence of matings having a positive effect on the quality of stored sperm. This suggests that post-meiotic intra-testicular sperm senescence does not occur at a fixed rate but may be modulated by external factors, such as temperature and number of matings.

In summary, the scientists at the Vetmeduni have shown that sperm senescence occurs while sperm are stored in the testicles of animals living under essentially "natural" conditions. They also suggest that the rate of sperm senescence can be slowed if males mate more frequently. For animals that produce sperm continuously, such as man, the implications seem to be that more frequent ejaculations serve both to remove older and thus less viable sperm as well as to reduce the damage to sperm cells during storage. The senior author on the PlosONE paper, Richard Wagner, is keen to speculate on the importance of the results. "We do not yet know how general post-meiotic sperm senescence is in wild animals, or man. But if it turns out to be widespread, it will be fascinating to see how it affects reproductive behaviour." As Hettyey says, "Females may try to avoid males with damaged sperm while males may choose particular environments that slow sperm senescence and may attempt to shorten periods of sexual rest by also accepting matings with low-quality females or by discharging aged sperm."

Contact: Dr. Richard Wagner
University of Veterinary Medicine -- Vienna

Related biology news :

1. Green leaf volatiles increase plant fitness via biocontrol
2. Traumatic mating may offer fitness benefits for female sea slugs
3. Iron, vitamins could affect physical fitness in adolescents
4. Cardio fitness levels of breast cancer patients may affect survival
5. Pond skating insects reveal water-walking secrets
6. Biophysicists unravel secrets of genetic switch
7. Ancient genome reveals its secrets
8. New model gives hands-on help for learning the secrets of molecules
9. Decoding the secrets of balance
10. Hidden secrets in the worlds most northerly rainforests
11. Large, medically important class of proteins starts to yield its secrets
Post Your Comments:
(Date:11/12/2015)...  Arxspan has entered into an agreement with ... use of its ArxLab cloud-based suite of biological ... will support the institute,s efforts to electronically manage ... internally and with external collaborators. The ArxLab suite ... Institute,s electronic laboratory notebook, compound and assay registration, ...
(Date:11/10/2015)... Nov. 10, 2015 About ... that helps to identify and verify the identity ... considered as the secure and accurate method of ... a particular individual because each individual,s signature is ... especially when dynamic signature of an individual is ...
(Date:11/2/2015)... Nov. 2, 2015  SRI International has been awarded ... preclinical development services to the National Cancer Institute (NCI) ... provide scientific expertise, modern testing and support facilities, and ... pharmacology and toxicology studies to evaluate potential cancer prevention ... The PREVENT Cancer Drug Development Program is an NCI-supported ...
Breaking Biology News(10 mins):
(Date:11/27/2015)... , November 27, 2015 ... Growing popularity of companion diagnostics is ... cancer biomarkers market with pharmaceutical companies and ... companion diagnostic tests. . ... Complete report on global cancer biomarkers ...
(Date:11/26/2015)... November 26, 2015 --> ... specializing in imaging technologies, announced today that it has received ... of the Horizon 2020 European Union Framework Programme for Research ... clinical trial in breast cancer. , --> ... --> --> The study aims ...
(Date:11/25/2015)... Nov. 25, 2015  PharmAthene, Inc. (NYSE MKT: PIP) ... a stockholder rights plan (Rights Plan) in an effort ... carryforwards (NOLs) under Section 382 of the Internal Revenue ... PharmAthene,s use of its NOLs could be substantially ... defined in Section 382 of the Code. In general, ...
(Date:11/25/2015)... , November 25, 2015 Studies ... and human plaque and pave the way for more effective ... in cats     --> ... commonly diagnosed health problems in cats, yet relatively little was ... Two collaborative studies have been conducted by researchers from the ...
Breaking Biology Technology: