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Proceedings of the National Academy of Sciences of the United States of America logoLink to Proceedings of the National Academy of Sciences of the United States of America
. 2018 Nov 6;115(45):11345–11347. doi: 10.1073/iti4518115

Shifting tropical cyclone hazards

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Uprooted trees in Hallasan National Park, South Korea, after Typhoon Bolaven struck in August 2012.

The long-term variability of tropical cyclone (TC) activity is unclear, largely due to discrepancies among data sets and brief instrumental records. Jan Altman et al. (pp. 11543–11548) estimated the long-term variability of TC activity in coastal northeast Asia based on forest canopy disturbance rates recorded in tree rings. As latitude increased between 33°N and 45°N, the frequency of canopy disturbance in trees within the first 15 years of life decreased, whereas the frequency of canopy disturbance after the 15th year increased, reflecting decreasing TC activity from south to north. The frequency of trees experiencing canopy disturbance between the 15th and 50th year increased with latitude more steeply for trees whose first ring appeared on or after 1920, compared with older trees. Consequently, the younger trees were significantly more likely to experience canopy disturbance at high latitudes. The frequency of experiencing canopy disturbance after the 50th year of life was much lower for post-1920 trees than for pre-1920 trees. The results suggest increased TC activity at northern sites after 1920. Regions currently at the edge of TC impact may experience increasing threat in the future, according to the authors. — B.D.

PolyQ proteins and neuronal toxicity

Neurodegenerative disorders such as Huntington’s disease and spinocerebellar ataxias (SCAs) are characterized by proteins with expanded polyglutamine (polyQ) regions—long stretches of the amino acid glutamine. The accumulation of misfolded polyQ proteins impairs neuronal functions, but the underlying molecular mechanisms are unclear. Min Jee Kwon, Myeong Hoon Han, et al. (pp. E10748–E10757) show that coiled-coil structures in polyQ regions of SCA type 3 (SCA3) proteins contribute to neuronal toxicity and behavioral abnormalities in fruit flies. The authors generated transgenic fruit fly lines expressing three structural variants of SCA3 polyQ proteins. Sensory neurons expressing the variant without coiled-coil structures showed no abnormalities in neuronal extensions called dendrites. By contrast, neurons expressing the two variants with coiled-coil structures exhibited various dendrite defects. Moreover, fly larvae expressing SCA3 variants with coiled-coil structures displayed movement abnormalities, such as increased head turning. Increasing the levels of the Foxo protein, which interacts with SCA3 polyQ proteins, reduced dendrite and motility defects induced by coiled-coil structures in sensory neurons and larvae. Taken together, interactions between Foxo and polyQ proteins containing coiled-coil structures may mediate neuronal and behavioral defects in fruit flies. According to the authors, the study suggests that inhibiting polyQ–Foxo interactions might be a viable therapeutic strategy for polyQ diseases. — J.W.

Funding requirements for lion conservation

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Male African lion (Panthera leo), Kafue National Park, Zambia. Image courtesy of Sebastian Kennerknecht (photographer).

Protected areas (PAs) are fundamental to international biodiversity conservation efforts. In Africa, where more than half the range of lions falls within PAs, funding shortfalls threaten to undermine the effectiveness of PAs. Peter Lindsey, Jennifer Miller, Lisanne Petracca, et al. (pp. E10788–E10796) collected 2015 funding data for 282 African PAs with lions in 23 countries. Lions face threats that affect many other species in Africa, making lions a useful proxy for the conservation status of wildlife. The PAs with lions received $381 million in total annual funding, with a median of $200/km2. Using three independent measures—the average annual spending on PAs managed by the African Parks Network, an empirical model developed by the authors, and a previously published estimate of lion management costs—the authors estimated the minimum funding required for effective lion conservation to be approximately $1,000–$2,000/km2 on average, or $1.2–2.4 billion total annual funding. Thus, the total annual funding deficit for all assessed PAs was $0.9–2.1 billion, with 88–94% of individual PAs with lions being underfunded. The results suggest that increased investment in African PAs is needed to prevent continued declines in lion populations, according to the authors. — B.D.

Global trends in swine infections

Pathogens affecting swine can have widespread global impacts, since pork represents more than one-fourth of all protein consumed and more than one-third of all meat produced. Globalization enhances the threat of pathogens to pork production, but little research has addressed global trends in infectious diseases that affect swine. Kimberly VanderWaal and John Deen (pp. 11495–11500) reviewed more than 57,000 publications from 1966 through 2016 that represented research on 40 swine pathogens. The authors examined trends in publications on pathogens over time, given that publication trends likely reflect trends in research priorities. The number of publications in the last 15 years covering eight pathogens increased faster than general publication trends, suggesting that the pathogens are emerging and have received increased research funding priority. Additionally, the authors examined multinational networks of swine pathogen research, identifying factors leading to international research collaboration. The authors found that countries were more likely to collaborate if they belonged to the same region, shared a common language, and had a colonial relationship. According to the authors, the results suggest that a global view of emerging threats and established networks can help the swine industry establish policies to reduce vulnerability. — P.G.

Fossilized lungs in a bird ancestor

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Archaeorhynchus specimen displaying preserved plumage and lung tissue. Image courtesy of J. Zhang (Institute of Vertebrate Paleontology and Paleoanthropology, Beijing).

Evolutionary developments that supported flight include unidirectional airflow in the lungs, supplementary air sacs, and lung tissue that is finely subdivided to maximize surface area. Extant in living crocodilians, unidirectional airflow is now considered ancestral to early feathered dinosaurs, but fossilized lung structures in early bird and dinosaur lineages had not previously been found. Xiaoli Wang, Jingmai O’Connor, et al. (pp. 11555–11560) analyzed a specimen of Archaeorhynchus spathula, an early bird that lived during the Cretaceous Period, via scanning electron microscopy. The authors focused on a speckly white material in the chest cavity not previously seen in Archaeorhynchus or any other fossil. The results of the fossil analysis revealed an extremely subdivided structure similar to that of modern bird lungs, which enables the high oxygen diffusion capacities necessary for powered flight. The authors also found in the preserved plumage a pintail feather structure not shared by other known Cretaceous birds but common in modern specimens. According to the authors, the results suggest that key avian structures were in place by the Early Cretaceous and may have helped modern bird ancestors survive the extinction of the dinosaurs. — P.G.

Spider web silk proteins in micellar nanoparticles

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Black widow spider.

The spider silk precursor solution in silk glands consists mainly of high concentrations of spidroin proteins, but the exact form in which the proteins are stored is unclear. Lucas Parent, David Onofrei, et al. (pp. 11507–11512) used a combination of solution phase diffusion nuclear magnetic resonance (NMR) and cryogenic transmission electron microscopy (cryo-TEM) to examine the physical form of the spidroin precursor nanostructures in the silk glands of black widow spiders. NMR revealed that the spidroin proteins exist as entangled volumes several hundred nanometers in diameter, suggesting the presence of spherical micelles. Cryo-TEM imaging of the nanostructures revealed that spidroins assemble into hierarchical micellar architectures composed of networks of flake-like subdomains. When the authors sheared the spider silk precursor by micropipetting, mimicking the silk extrusion process of the spider’s spinning duct, the subdomains transformed from flake-like structures to narrow and elongated fibrils. The findings indicate that changes in the subdomains within hierarchical micellar assemblies are a first step in the production of spider silk fibers. According to the authors, the results could aid the development of artificial silks that mimic spider silk. — S.R.


Articles from Proceedings of the National Academy of Sciences of the United States of America are provided here courtesy of National Academy of Sciences

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