Highlights from the BMC series in February 2015

Shisha smoke • Downy mildew disease in lettuce • Cichlid fish evolution • Lifespan extension in worms • Magnesium intake and blood pressure • Video recording of dogs seizures


Public health: Shisha smoke contains more heavier metals than previously thought

Smoking Shisha is not safer than smoking cigarettes. The percentage of metals removed during the water filtration stage is, in fact, only around 3% of the total metal concentration. This fraction does not protect against exposure to the majority of potentially toxic metals. As discussed by Mike Knapton from the British Heart Foundation in his guest blog, there is no safe way to smoke and smoking Shisha is not an exception. Because Shisha is smoked for a longer time, smoking for a whole evening can be the equivalent of smoking a hundred cigarettes in one session.

Microbiology: Downy mildew disease promotes colonization

The recent outbreaks of foodborne infections linked to lettuce prompted an investigation into the influence of plant diseases in the invasion of human pathogens. Downy mildew, an endemic disease of lettuce caused by fungus-like Bremia lactucae, causes necrosis of the plant tissues when they are near harvest maturity, just before reaching the consumers. The lesions caused by this organism act as portals for the invasions of other pathogens, including human pathogens Escherichia coli O157:H7 and Salmonella enterica, which proliferate thanks to the high humidity in the tissues. This discovery suggests that downy mildew may represent an important risk factor of microbial contamination of lettuce and that resistant plants may lower the risk of such contaminations.

Evolutionary Biology: Cichlid fish evolution in Ugandan lakes

Cichlid fish in East Africa are known for their great phenotypic diversity and fast speciation. The fish living in 50 crater lakes in southwestern Uganda provide an excellent example of species independently following the same evolutionary patterns. With the first phylogeographical investigation of its kind, researchers investigated the influence of geographical isolation and natural selection on phenotypic diversification and speciation of cichlid fish. Each of the crater lakes constitutes a separate population with a strong pattern of parallel genetic and morphological differentiation, in particular towards a more limnetic-like body shape. This great differentiation also means that several endemic species could still be discovered in this environment.


Image of the month

Image of the month feb 2015
This picture shows the histological analysis of dwarf deer Candiacervus femora at different ages. Such analysis provide insights about growth and life history patterns in extinct mammals.
From Kolb et al. BMC Evolutionary Biology 2015 15:19

Genetics: Lifespan extension in worms

To test the effects of amino acids on Caenorhabditis elegans lifespan, individual amino acid supplementation was tested, demonstrating an effect with 18 of the 20 proteogenic amino acids. Serine, proline, and tryptophan showed the greatest effects, with different metabolic pathways involved in each case. Amino acid and protein supplementation are widely used in the human diet and they may have an influence on aging and aging-associated disorders. However, it remains to be determined whether or not such supplementation strategies will apply to higher eukaryotes.

Nutrition: Can magnesium intake affect blood pressure?

The association between dietary magnesium intake and incidence of hypertension has long been suggested but there are epidemiological inconsistencies when trying to demonstrate it. This cohort study on an adult Mexican population found that the association between magnesium intake and hypertension is not significant. However, a modest inverse association with blood pressure cannot be ruled out.

Veterinary research: Is that a seizure?

Videos recorded by pet owners are increasingly used when the animals are showing unusual and worrying behaviours, as during a seizure-like event. Researchers sought to investigate if such videos are useful to determine whether the animal is indeed experiencing a seizure-like event, and of which kind. The study showed a low level of agreement among vets, highlighting the limitations in the use of these videos and the need for a robust seizure classification system.

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