Research shows how females choose the 'right' sperm

Main Category: Biology / Biochemistry
Also Included In: Pregnancy / Obstetrics
Article Date: 20 Aug 2013 - 0:00 PDT Current ratings for:
Research shows how females choose the 'right' sperm

University of East Anglia scientists have revealed how females select the 'right' sperm to fertilize their eggs when faced with the risk of being fertilized by wrong sperm from a different species. Researchers investigated salmon and trout, which fertilize externally in river water. The two species occasionally hybridize in the wild, but since hybrid offspring become reproductive dead-ends, females of both species are under selection to avoid hybrid fertilizations, and instead promote external fertilization by their own species' sperm.

Findings published in the journal Evolution show that when eggs from each species are presented with either salmon or trout, they happily allow complete fertilization by either species' sperm. However, if eggs are given a simultaneous choice of both species' sperm, they clearly favour their own species' sperm.

Lead researcher Prof Matt Gage (pictured), from UEA's School of Biological Sciences, said: "The salmon-trout system is ideal for studying sperm-egg compatibilities because we are able to conduct controlled fertilization experiments and measure sperm behaviour under conditions to which the gametes are naturally adapted. Although we found almost 100% interfertility between salmon and trout sperm and eggs, when we mixed equal amounts of sperm from both species together, we found that sperm from their own species won 70 per cent of the fertilizations."

"Since we are conducting in vitro fertilizations without interference or control from males or females, this provides clear evidence that eggs favour the sperm of their own species, but only when given a choice."

The team then went on to investigate what mechanisms allow female eggs to encourage the right sperm to fertilize by examining two key components of reproduction in female fish - the egg, and the ovarian fluid that coats the egg. Ovarian fluid is a protein-rich solution that bathes the eggs and released at spawning - but little has been known about its function.

Prof Gage said: "We ran further sperm competition trials but this time we rinsed eggs of their ovarian fluid and then added back either their own fluid, or that from the other species. Remarkably, we found that the egg itself plays no significant role in promoting fertilization precedence by their own species' sperm. Instead, it is actually the ovarian fluid that controls which species' sperm wins the fertilizations, which was very unexpected. If we put salmon ovarian fluid onto salmon eggs, then salmon sperm win, but if we put trout ovarian fluid onto eggs from that same salmon female, trout sperm now win."

The researchers then used Video Tracking Analysis to analyse how salmon and trout sperm behave in ovarian fluid.

"We found that activating sperm in ovarian fluid makes them live about twice as long as in river water. Importantly, both species' sperm also switch from swimming in tight elliptical circles in river water, to swimming in straightened trajectories in ovarian fluid. This behaviour allows sperm to navigate towards the egg by following a chemical cue."

"So what we're seeing is that ovarian fluid gives a specific chemical signal to the sperm of its own species, causing changes in the way their tails beat, so that they swim in a straighter trajectory, and therefore guided more effectively towards the site of fertilization."

To establish that this was the mechanism which promoted fertilization precedence by their own species' sperm, the research team ran a final experiment in which they measured sperm migration across a membrane permeated with tiny pores mimicking the single entrance into the egg. They found that many more sperm swam through the membrane into their own ovarian fluid, compared with numbers crossing into the other species' ovarian fluid or water.

"These findings allow us to establish that females have indeed evolved mechanisms of 'cryptic choice' at the intimate level of the sperm and egg. The results also give us a valuable insight into why female salmon mate so promiscuously - typically being fertilized by eight, and up to 16, males in one nest. By promoting sperm competition, females provide their eggs with greater choice, allowing ovarian fluid to avoid potentially hybridizing sperm, and instead encourage fertilization by the right sperm."

'Cryptic Choice of Conspecific Sperm Controlled by the Impact of Ovarian Fluid on Sperm Swimming Behaviour' * is published by the journal Evolution.

Article adapted by Medical News Today from original press release. Click 'references' tab above for source.
Visit our biology / biochemistry section for the latest news on this subject.

The research was funded by the Natural Environment Research Council (NERC) and a collaboration between UEA, the Norwegian Institute for Nature Research, and the Institute of Zoology.

* CRYPTIC CHOICE OF CONSPECIFIC SPERM CONTROLLED BY THE IMPACT OF OVARIAN FLUID ON SPERM SWIMMING BEHAVIOR

Article first published online: 12 AUG 2013; DOI: 10.1111/evo.12208

University of East Anglia

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'No such thing' as left or right brained people

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Main Category: Neurology / Neuroscience
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Article Date: 19 Aug 2013 - 1:00 PDT Current ratings for:
'No such thing' as left or right brained people

We have all heard references to people being a "left-brained" or "right-brained" thinker. But researchers from the University of Utah say their latest research shows this is a myth.

Previous studies over the years have suggested that we use one half of our brain more often than the other, playing a part in the type of personality we have.

While the left side of the brain is usually associated with logical, analytical and detail-oriented behavior, the right side has been connected to creative, thoughtful and subjective thinking.

But a new study published in the journal PLOS ONE, suggests there is no evidence within brain imaging that proves some people are right-brained or left-brained.

The research team conducted a two-year study of 1,011 people who were part of the International Neuroimaging Data-Sharing Initiative (INDI), and who were between the ages of 7 and 29.

All participants had the functional lateralization of their brains measured. Functional lateralization means there are specific mental processes that take place in either the brain's left or right hemisphere.

Researchers have said the theory of "left-brained" or "right-brained" thinkers is nothing more than a myth

The scientists conducted the brain measurements using magnetic resonance imaging (MRI) analysis, which involved the participants lying in the scanner for 5 to 10 minutes while their "resting" brain measurements were taken. This allowed the researchers to correlate brain activity in one area of the brain and compare it with another.

The researchers then divided the brain into 7,000 regions and analyzed which regions of the brain showed more functional lateralization.

All connections in the brain were examined, and all possible combinations of the brain regions were correlated for each brain region that was left-lateralized or right-lateralized.

The results of the scan showed patterns indicating that a brain connection may be strongly left or right-lateralized. But they found no relationship that individuals "preferentially" used their left-brain network or right-brain more often.

Dr. Jeff Anderson, lead author of the study, explains:

"It is absolutely true that some brain functions occur in one or the other side of the brain. Language tends to be on the left, attention more on the right.

But people don't tend to have a stronger left- or right-sided brain network. It seems to be determined more, connection by connection."

Jared Nielsen, a graduate student in neuroscience at the University of Utah and one of the study authors, adds:

"If you have a connection that is strongly left-lateralized, it relates to other strongly lateralized connection only if both sets of connections have a brain region in common."

Results of this study are groundbreaking, Nielsen says, as they may change the way people think about the "right-brain versus left-brain theory."

"Everyone should understand the personality types associated with the terminology 'left-brained' and 'right-brained' and how they relate to him or her personally," he says.

"However, we just do not see patterns where the whole left-brain network is more connected or the whole right-brain network is more connected in some people. It may be that personality types have nothing to do with one hemisphere being more active, stronger, or more connected."

Written by Honor Whiteman Copyright: Medical News Today
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Mixing ISO-14001, Environment, and OHSAS-18001 Safety and health, Right into a Unified System

Mixing the ISO-14001 Environment Management and OHSAS-18001 Safety and health Management standards right into a single, unified system, can provide substantial advantages over applying scalping strategies individually. Costs could be reduced having a single, combined group of documentation, reduced training costs, along with a lower registration audit cost. This is actually the most practical and least time intensive road to registration.

ISO-14001 and OHSAS-18001 are two of the most common and many asked for ISO management systems outdoors from the ISO-9001 (or even the more industry specific AS-9100, ISO/TS-16949, and ISO-13485) Quality Management System. Increasingly more forward thinking information mill asking for their providers come with an effective Environment Management system in-place. This is particularly important when confronted with companies whose public image is essential for them. Many European information mill flowing lower their environment management needs for their sub-tier providers too. When you are registered towards the ISO type quality system, adding registration towards the Environment and Safety and health standards isn't difficult whatsoever. You have the knowledge of how scalping strategies work and just how they're given, enhanced and maintained. Which means that applying both can't only help you save considerable money over applying individually, but it will likewise enhance your company's bottom lime once the savings of controlling these critical facets of business begins to start working. Applying both of these management systems greatly reduces your company's contact with legal cases too. Let us examine all these systems and discuss how effective implementation can help you save money and control risks.

ISO-14001 may be the Worldwide Environment Management standard. This is actually the second most implemented ISO system. By 2012, nearly one fourth of the million companies have grown to be ISO licensed. The ISO 14001 standard doesn't dictate environment performance needs. Rather, it works as a framework to help organizations in developing their very own environment management systems. ISO 14001 could be integrated along with other management functions and assists companies in meeting their environment and economic goals. ISO 14001, like ISO-9001 is extremely scalable, therefore it might be put on any size or kind of organization, service or product, in almost any sector of activity, so whether you've three or 5,000 employees, manufacture hazardous chemicals, or only produce intellectual property, you are able to approve your company to ISO-14001.

OHSAS-18001 is really a virtual mirror of ISO-14001 other than it focuses its management efforts around the company's safety and health issues instead of its environment issues. Because of this applying both isn't a lot more difficult than applying just one. A lot of the effort in applying these is training the employees how you can effectively rely on them. ISO accreditation agencies and registrars recognize this to allow them to provide a reduced registration audit when you are performing both systems concurrently - over a 30% reduction.

Additionally to enhanced procedures efficiencies, applying these standards can lead to a large discount in insurance charges. Both insurance, as you have substantially less contact with legal cases, and workers comp insurance, since you address, monitor and manage your company's safety and health issues, could be reduced - sometimes having to pay back the price of implementation is really a single year, based on your company's size, exposure along with other relevant issues.

Learning and applying the ISO-14001 Environment Management and OHSAS-18001 Safety and health Management standards, whilst not hard for a previously qualified ISO-9001 Quality System manager, simply requires trading time to get learning both of these standards as well as in how you can mix them. Many methods and techniques could be combined. For example, you simply need one corrective action procedure, one management review meeting, and a bouquet of documents which will cover the needs of both standards. One method to ease this time around consuming process is to apply qualified and trained consultants. Should you want to follow this path, make sure your consultants are not only seen trained on the ISO-14001 and OHSAS-18001 standards, but additionally regarding how to mix them right into a single combined system. ANAB accredited registrars are actually offering Lead Auditor practicing combined management systems.

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