Highlights of the BMC-series: November 2013

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Origins of avian vision • A mating strategy to ruffle some feathers • Boomerang birds? • Microbes in space • A battery of neuropsychological tasks • Bulimia and body image • A need for better definition • Filling in the details on tooth decay risk

Evolution: Origins of avian vision

Male bowerbirds are famed for building elaborate structures from colourful found objects, in order to woo their mates. Because of this, they’ve become something of a model organism for studying the evolution of vision in birds. A new study now analyses the sequences of light-sensitive proteins called opsins to confirm that UV sensitivity in the visual system of the Great Bowerbird has re-evolved from violet-sensitive ancestors several times –representing an unusual exception among vertebrates.

Genetics: A mating strategy to ruffle some feathers

Another highly unusual avian mating system is found in a wading bird called the ruff. Males of this species are found in three different colour morphs, each of which uses a different strategy to attract a mate. One of these has only recently been identified, since it closely mimics the colouration of the more drab females, whilst the development of the other two more colorful morphs are known to be genetically linked. Development of this female-mimic morph has now been found to be controlled by loci unlinked to the other two morphs, with the allele for this trait located in the same region as that of melanin-based colouration.

Ecology: Boomerang birds?

Defining the precise time at which a bird can be said to have fledged their nest is difficult, since juveniles of some species may return home periodically at various stages of their development. Now, by analysing the movement behaviour of juvenile golden eagles by fitting them with GPS trackers, researchers in Scotland have been able to pinpoint the precise time of this fledging event, whilst also developing a new method to provide more robust estimates on emigration than previous approaches.

Astrobiology:  Microbes in space

Odd things can happen in the microgravity of space, and this is not just restricted to large-scale organism like you and I. Microorganisms growing on an artificial media mimicing human urine have been found to alter their growth and physiology in response to spaceflight. Pseudomonas aeruginosa cultures grown under nutrient-limiting conditions reach higher cell densities in the microgravity of space compared to those grown on Earth, which may have important  implications for the health of crew who work in this unusual environment.

Image of the month:

Fig 2 Kopp et al BMC Neurology 2013 13, 179Anatomical results from lesion subtraction analysis on the Frontal Assessment Battery tests, a brief battery of six neuropsychological tasks designed to assess frontal lobe function at bedside in stroke patients. From Kopp et al. BMC Neurology 2013, 13:179.

Psychiatry: Bulimia and body image

A functional magnetic resonance imaging study of women with bulimia finds that their brain responses only differ from those of healthy controls when viewing pictures of slim women, not when viewing images of food. These findings therefore suggest that women suffering from  bulimia may differ from healthy women in the way that they process images of the body, but not in the way they process food stimuli.

Pregnancy and childbirth: A need for better definition

Defining what is encompassed by the term “maternal health” is not straightforward, but broadening this definition beyond simple measures of maternal mortality could help efforts to improve global health. However, significant discrepancy in literature and expert opinion still exists concerning this definition. A literature review and questionnaire of leading experts in the field concludes that measurements of maternal morbidity across the world should be based on standard definitions to allow proper comparisons across regions and to correctly inform future policy.

Medical genetics: Filling in the details on tooth decay risk

Analysis of seventy-two pedigrees from people in the Philippines using fine mapping identifies a functional SNP on chromosome 13 associated with higher experience of dental caries. The higher expression of a glucocorticoid receptor transcription factor in the saliva of individuals with lower experience of caries also suggests that this may have future potential as a diagnostic biomarker.

 

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