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Open Reading Frame brings together a selection of recent publication highlights from elsewhere in the open access ecosystem. This week we take a look at the past few weeks in biology.


Tropical birds battle a bottleneck
When species are threatened with extinction, reduced population sizes pose a real problem. Not only are mates more difficult to find, but conservation efforts may be hampered by limited genetic diversity among the individuals that remain – creating what is known as a ‘genetic bottleneck’. Generating new viable populations by transporting individuals away from threatened areas is a common approach for at-risk species, but there is no consensus on whether it is more important to conserve overall genetic diversity, or to target only diversity at important functional genes. The Seychelles warbler is one example of a species brought back from the brink of extinction by conservation efforts. This tropical species has been closely monitored since populations dwindled to less than 50 birds in the mid-20th century, with new populations founded across several islands in the Seychelles archipelago over the past 23 years. Analysis of genetic data from these efforts finds that although only around 20-25 birds would be required to capture the majority of genetic  diversity in functional immune-related genes, the use of neutral genetic markers may be a more efficient and cost effective way of optimizing conservation efforts aimed at preserving genetic diversity.
Wright et al. Molecular Ecology


Short men are long in the tooth
An observational study of more than 8,000 men finds a positive association between height and longevity. Using data from a large-scale heart and aging study of Japanese-American men living in Hawaii, researchers find that a gene previously linked to human longevity and insulin signalling called FOXO3 is more prevalent among shorter men, with those around 5 feet 2 inches in height living the longest. Although the precise mechanism driving this association has not been fully established by the study, the authors speculate that complex interactions in nutrient- and energy-sensing biological pathways regulated by this gene could be responsible.
He et al. PLoS One


New plant species has a taste for heavy metal
A new species of plant from the violet family has been discovered in the Philippines that displays a remarkable ability to accumulate nickel. Only around 500 plant taxa are known to accumulate heavy metals in their shoot tissues without suffering  toxic effects, representing less than one percent of all known flowering plant species. The plant Rinorea niccolifera, whose species name is derived from the Latin ‘to contain nickel’, was found to contain metal in its leaf tissue at concentrations of more than 18,000 parts per million, classifying it as a nickel hyperaccumulator. Although only discovered in 2012, the species already meets International Union for Conservation of Nature (IUCN) red list criteria of being endangered in the wild, as it is restricted to less than 500 km2 of native habitat that is threatened by fragmentation from open pit mining. Although some closely related species have a more widespread distribution, knowledge of how plants are able to survive under such extreme physiological stress could help future efforts in using plants as tools in phytoremediation of contaminated soils.
Fernando et al. PhytoKeys


Extending life, enhancing cognition
The presence of a lifespan-enhancing regulator protein called klotho, named after the Greek goddess responsible for ‘spinning the thread of life’, has now been associated with enhanced cognitive ability. Previous data from mice has shown that a lack of klotho in developing embryos results in cognitive impairment as well as reduced lifespan, suggesting that it may be a key component of brain maturation. To investigate this association further, mice that overexpressed klotho were subjected to a battery of learning and memory tests and found to perform better than control mice, who exhibit regular expression levels of the protein. How broad are these findings when applied to humans? Enrolling more than 700 people over the age of 50, they also find evidence for enhanced cognition and memory performance among subjects that carried the lifespan-extending variant of the human KLOTHO gene, suggesting it may be a good target for further work on combating age-related cognitive decline.
Dubal et al. Cell Reports


What does the impact factor of a Nobel laureate look like?
The journal impact factor is a commonly used – and controversial – metric for assessing the scientific output of researchers, as well as the institutions where they work. It’s controversy lies primarily in the fact that it is a metric derived not from individual article citations, but from the accumulated citations of all articles published in a journal. Large variations in the number of citations within a journal therefore mean that highly-cited works may be undervalued at the individual level, whilst the reverse may be true of poorly-cited works. An alternative metric developed by researchers from Aalto University in Finland, termed the Author Impact Factor (AIF), aims to bring the evaluation of research output back to the individual level, by measuring trends in researcher’s citations rates throughout their careers. As illustrative examples, they calculate the AIF for a number of Nobel prize winners, highlighting the variation in citation rates – in particular sharp peaks during key periods in their careers – leading up to receiving their prize.
Pan & Fortunato. Scientific Reports


Bacteria hitch a sperm ride across generations
Symbiotic bacteria that live inside host cells can be found in many species of plants, animals and fungi, and are most often transmitted across generations through the female line, as eggs provide ample cellular space in which bacteria can survive. In contrast, sperm cells contain little or no cytoplasm, creating a sex-biased transmission route. However, in the first reported case of paternal symbiont transmission, researchers from Tsukuba in Japan have identified a species of leafhopper insect in which a bacteria called Rickettsia is able to find room enough inside sperm to cross the generational divide. Instead of hiding out in the cell cytoplasm, Rickettsia targets the sperm cell nucleus as the route of cross-generational infection without any apparent drop in transmission efficiency, which might be expected if normal genetic functioning was impaired.
Watanabe et al. PNAS


Written by Simon Harold, Senior Executive Editor for the BMC Series. 


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