Category: Biology

According to The Register, levels of the “satisfaction” hormone prolactin do not reach as high a peak following manual stimulation in men as they do after purportedly procreational activity with a partner.

The original research published in Biological Psychology could explain what The Register describes subtly as a “niggling dissatisfaction” following the former approach to gratification. Needless to say, the remainder of their article is anything but subtle and the link above should only be followed if you’re feeling up to blatant sexual innuendo.

Differences in immune response between males and females appear at puberty, according to a study published today in the journal BMC Immunology.

The differences in the male and female immune responses, which make females more prone to autoimmune disease and males more subject to infection, are established during puberty, report US scientists who have identified one of the mechanisms responsible for the difference in immune response between male and female mice. They show that this sexual disparity is established during puberty and is influenced by sex hormones. These findings have implications for studies of autoimmunity, transplantation and vaccination.

Kanneboyina Nagaraju and Eric Hoffman’s groups from the Children’s National Medical Center, Washington DC, and colleagues elsewhere in the USA, used microarrays to study 12,000 genes expressed in the spleen of pre-pubertal, pubertal and post-pubertal male and female mice.

The results show that a number of genes are upregulated in both males and females during puberty. The authors found that genes involved in the innate immune response, which provides an immediate defence against pathogens and involves phagocytic cells such as macrophages, were significantly underexpressed in pubertal and post-pubertal females. Genes involved in the adaptive immune response, which provides a long-lasting protection and involves antibodies or ‘immunoglobulins’, were overexpressed in pubertal and post-pubertal females compared with males. This difference in expression was not found in pre-pubertal mice, indicating that the sexual disparity in immune system expression is established during puberty.

The researchers have also demonstrated that the differences in immunoglobulin expression between males and females are controlled by a gene signalling pathway called the Fas/FasL pathway, which is modulated by the female sex hormone estrogen.

SOURCE: BMC Immunology press release.

Our brains have a specific mechanism for recognising human faces that is separate from the mechanism that allows us to recognise objects like houses, cars, horses or even
parts of the body, according to Brad Duchaine of University College London. In a forthcoming paper in the journal Cognitive Neuropsychology, he shows how we recognise faces by analysing
one man, who cannot tell one face from another.

I assume he’s not generalising from this one case to the whole human race, but it’s an intriguing piece of work nevertheless.

Duchaine said: ‘There have been many theories about whether there is a part of the brain that deals specifically with faces or whether faces and other objects are handled by the same brain areas. We’ve found that there is a different, very separate, bit of the brain that lets you recognise faces. If those cells aren’t working, someone may not be able to tell two faces apart but they
will recognise two horses apart. This indicates that we go about looking at, analysing and recognising faces in a different way from how we recognise objects.

‘There are many theories out there about how we recognise faces and whether there is a separate social bit of the brain. So that we could draw firm conclusions to prove our facial recognition theory, we addressed all the alternatives in a single case study — Edward, a 53 year-old married man with a PhD in theology and physics, who happens to be unable to
recognise faces.’

For more than 35 years, researchers have debated whether face recognition is carried out by face-specific mechanisms or whether it involves more generic mechanisms that are also used for objects. Prosopagnosic patients (people who have difficulty recognising faces) have been some of the most powerful sources of evidence for there being face-specific mechanisms.

Scientists have put forward a number of different theories about why some people can’t recognise faces. One theory states that people with face recognition just have problems with objects that have a lot of curved surfaces (Curvature explanation); another theory states that it’s caused by problems with perceiving distances between parts such as judging the distance between eyes (Configural-processing explanation); another puts it down to a problem in recognising any individual item in a class — objects and faces (individuation explanation); another points to an inability to develop expertise with regularly encountered objects
(Expertise explanation).

But, for each case of prosopagnosia that has been scientifically tested there have always been several untested alternative explanations that could account for the inability to recognise faces. Each of these individuals has not been sufficiently tested to provide conclusive evidence for face-specific processes.

This study addresses all the existing theories that make a case against there being a specific mechanism in the brain that deals just with faces. Duchaine said: ‘We reject each in turn and eliminate all alternative accounts. The results show that face recognition uses mechanisms in the
brain that are different from those used in recognising anything else.’

The tests at UCL were done using a variety of types of objects — horses, guns, cars, greebles (novel objects). Edward performed just as well on as the test group people at differentiating between different objects but he just couldn’t tell faces apart.

Nathaniel Szewczyk and colleagues are experts in the nematode worm Caenorhabditis elegans, this popular little organism has been the subject of countless biological studies including Nobel-prize winning efforts. As such, it is being developed as a model system for space biology.

According to Szewczyk, the chemically defined liquid medium, C. elegans Maintenance Medium (CeMM), allows it to be cultivated automatically and experiments to be carried out on it during spaceflight research. His team grew CeMM for experiments to be carried out on board STS-107, space shuttle Columbia.

When tragedy struck Columbia, a massive recovery effort was started and hardware containing the CeMM experiment was actually retrieved from the debris.

Szewczyk explains that live animals were observed in four of the five recovered canisters, which had survived on both types of media. “These data demonstrate that CeMM is capable of supporting C. elegans during spaceflight. They also demonstrate that animals can survive a relatively unprotected reentry into the Earth’s atmosphere, which has implications with regard to the packaging of living material during space flight, planetary protection, and the interplanetary transfer of life,” Szewczyk explains.

You can read more about this rather unusual rescue mission in the journal Astrobiology 5, 690—705
Astrobiology.

I’ve mentioned the Fierce Biotech freebie email biotech industry newsletter before, but it’s well worth reminding Sciencebase readers of what a great resource it is. It’s now available for free in the USA, Canada, Mexico, and the UK. All you have to do to qualify for a free year’s subscription is fill in your details on the form and provide a little feedback on your job function (so they can decide whether you qualify). Once you’ve done that, you’ll starting receiving the free email newsletter within a day or two. The Fierce Biotech ezine covers the latest industry news on a daily basis and your acceptance for a free subscription helps support Sciencebase.

Newsletter description – “FierceBiotech is an easy to read daily email service that brings must read biotechnology news to senior executives in the biotech industry…one quick email per day keeps you up to speed on biotech companies and the biotech industry.” This newsletter will save you time and effort in keeping ahead of the competition.

We reported on claims to have found the world’s smallest fish that appeared in the Proceedings of the Royal Society of London B. The aquatic critter measured just 7.9 mm apparently and was found in a peat swamp in Southeast Asia. However, it seems the authors of the paper failed to note that a much, much smaller sexually mature angler fish was reported in the autumn of 2005 at just 6.2 mm to 7.4 mm in length.

So, what’s a few millimetres between friends? The female of the species in question, Photocorynus spiniceps presumably sees the significance, she comes in at a wopping 46 mm (some 7 seven times longer than her mate).

The smaller fish was reported in the journal Ichthyological Research and according to the study, the male is essentially a sexual parasite. He fuses for life to the back of his mate by biting on and turns the female into a hermaphrodite, providing her body with everything she needs to reproduce, she provides the food and navigational skills.

Again, size is everything for this arduous task, male spiniceps have testes so unfeasibly large that they almost fill his entire body cavity, even to the point of crowding out his other internal organs. Still, what fish is going to care about his internal organs when he’s perpetually mating and getting fed in the process?