Towards an ecology of soil microplastics Helmberger, Maxwell S.; Tiemann, Lisa K.; Grieshop, Matthew J. ...
Functional ecology,
March 2020, 2020-03-00, 20200301, Letnik:
34, Številka:
3
Journal Article
Recenzirano
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Microplastic pollution is a topic of increasing concern for the world's oceans, freshwaters and, most recently, soils. Microplastics have been found in soils across the globe. Like other ...anthropogenic pollutants, they can negatively affect a range of soil organisms through several mechanisms, though often dependent on particle size, shape and polymer type.
However, microplastics are unique among pollutants due to the diversity of ways in which soil organisms may themselves be able to affect their occurrence and distribution and mediate their effects on the rest of the soil food web.
In this review, we argue for a more explicitly ecological framing of this novel issue for the soil environment and discuss their potential interactions with soil communities, including microplastic formation via microbial and faunal fragmentation of large plastic debris and organisms such as earthworms placing microplastic particles in unique pedological contexts they could not otherwise reach. Ecological interactions may be crucial for dictating microplastics’ ultimate fate and effect on terrestrial ecosystems.
A free Plain Language Summary can be found within the Supporting Information of this article.
A free Plain Language Summary can be found within the Supporting Information of this article.
Cells form and use biomolecular condensates to execute biochemical reactions. The molecular properties of non-membrane-bound condensates are directly connected to the amino acid content of disordered ...protein regions. Lysine plays an important role in cellular function, but little is known about its role in biomolecular condensation. Here we show that protein disorder is abundant in protein/RNA granules and lysine is enriched in disordered regions of proteins in P-bodies compared to the entire human disordered proteome. Lysine-rich polypeptides phase separate into lysine/RNA-coacervates that are more dynamic and differ at the molecular level from arginine/RNA-coacervates. Consistent with the ability of lysine to drive phase separation, lysine-rich variants of the Alzheimer's disease-linked protein tau undergo coacervation with RNA in vitro and bind to stress granules in cells. Acetylation of lysine reverses liquid-liquid phase separation and reduces colocalization of tau with stress granules. Our study establishes lysine as an important regulator of cellular condensation.
The emerging threat that microplastic pollution poses to soil and its biota necessitates the development of methods to detect microplastic ingestion by soil animals. Fluorescent staining with Nile ...red dye has proven to be effective at distinguishing microplastics from inorganic and some biological material but is not suitable for separating them from invertebrate remains. Here, we report on the development and validation of a novel fluorescent counterstaining technique for detection of microplastics within terrestrial invertebrate biomass and fecal material. After being stained with a blend of Calcofluor white and Evans blue dyes in addition to Nile red, ground arthropod biomass appeared blueish-purple, whereas different plastic polymers appeared red, green, and yellow when viewed under laser scanning confocal microscopy. Nonarthropod invertebrate biomass and fecal material were also distinguishable from plastic, though to a lesser extent. Our results highlight the value of this method for detecting microplastic ingestion by terrestrial invertebrates.
Spotted-wing drosophila (Drosophila suzukii, (Matsumura)) is an invasive vinegar fly that has become a serious threat to soft fruit crops. Monitoring for this pest is typically performed using ...drowning traps baited with live yeast cultures or fermentation volatile blends. Trapping programs using these compounds provide highly variable results across production systems, geographic regions, and growing seasons. Trap competition with fruit is one hypothesis for this inconsistency. This study evaluated the trapping efficiency of yeast and wine baits in the presence and absence of small quantities of host fruits in two binary-choice laboratory experiments. The first experiment evaluated trap capture in clear 946-ml traps with easily accessible water, apple pomace, blueberry, raspberry, strawberry, cherry, or grape as competitive influences. The second experiment evaluated the same competitors, but they were made less accessible. Recapture of flies in arenas containing competitive fruit was reduced by 64–88% when fruit was ‘accessible' and from 0 to 51% when it was ‘inaccessible’ compared with arenas containing a water competitor. All fruit types provided statistically similar levels of trap interference. In the first experiment, yeast captured more flies compared with wine, whereas in the second experiment, wine captured more flies than yeast. Our results support the hypothesis that the presence of fruit or other reproductive resources will reduce trap captures and that this reduction is likely mediated by the relative accessibility of the fruit versus the trap. Thus, attempts to develop population estimates based on traps should incorporate fruit availability/accessibility.
The release of paused RNA polymerase II into productive elongation is highly regulated, especially at genes that affect human development and disease. To exert control over this rate-limiting step, ...we designed sequence-specific synthetic transcription elongation factors (Syn-TEFs). These molecules are composed of programmable DNA-binding ligands flexibly tethered to a small molecule that engages the transcription elongation machinery. By limiting activity to targeted loci, Syn-TEFs convert constituent modules from broad-spectrum inhibitors of transcription into gene-specific stimulators. Here we present Syn-TEF1, a molecule that actively enables transcription across repressive GAA repeats that silence frataxin expression in Friedreich’s ataxia, a terminal neurodegenerative disease with no effective therapy. The modular design of Syn-TEF1 defines a general framework for developing a class of molecules that license transcription elongation at targeted genomic loci.
The arrival of spotted wing Drosophila, Drosophila suzukii (Matsumura), to the United States has caused many berry and cherry growers to replace IPM programs with calendar-based broad-spectrum ...insecticide programs. Alternative management tactics are urgently needed to mitigate the current dependency on chemical control. Postharvest burial is a cultural crop sanitation strategy that has the potential to reduce D. suzukii reproductive habitat and eliminate infested fruit wastes. This study revealed that D. suzukii rarely pupate on the soil's surface or below 1 cm, but are capable of unburying themselves from depths up to 48 cm. Although zero emergence was not obtained in the field, adult emergence decreased exponentially with deeper burial depths. A burial depth of 24 cm reduced D. suzukii emergence by 97%, although soil texture may influence this optimal burial depth. Soils that had a higher concentration of sand had a negative impact on D. suzukii survival at shallower burial depths. The mechanism behind the reduction in adult emergence from differing burial depths remains unclear as the lipid concentration between emerging D. suzukii was the same regardless of burial depth.
Microplastics present a novel and potentially unique threat to soil ecosystems, one whose effects may be mediated by soil organisms themselves. We investigated fragmentation of polystyrene (PS) foam ...into microplastic particles by two isopods, Oniscus asellus L. and Trachelipus rathkii Brandt, in laboratory arena experiments. First, we examined the temporal dynamics of fragmentation across a time span of 96 h. O. asellus produced more fragments than T. rathkii, and neither species significantly fragmented the PS foam until 48 h had passed. Second, we asked whether O. asellus would still fragment PS foam in the presence of an alternate, more natural substrate like wood. Wood did not significantly affect fragmentation rates, in line with the few other studies examining the effect of alternate food on soil invertebrates' propensity to consume and/or fragment plastics. Our results provide additional characterization of PS foam fragmentation by isopods and indicate that laboratory experiments involving soil invertebrates and plastic debris can take place over relatively short timespans of four or fewer days, but do not necessarily need to provide alternate food to prove that plastic consumption would still occur in its presence.
Trap captures of obliquebanded leafroller, Choristoneura rosaceana (Harris), to pheromone blends in ratios approximating those reported in pheromone glands and a novel blend based on a volatile ...headspace collection from live virgin females were evaluated in field experiments in Michigan apple orchards. In an initial field trapping study, pheromone lures composed of either a three‐ or four‐component blend approximation of the blend present in female pheromone glands at doses ranging from 0.1 to 20 mg/lure were compared. The four‐component blend was a combination of (Z)‐11‐tetradecenyl acetate (Z11‐14:Ac), (E)‐11‐tetradecenyl acetate (E11‐14:Ac), (Z)‐11‐tetradecenol (Z11‐14:OH) and (Z)‐11‐tetradecenal (Z11‐14:Al) in a ratio of 96.5:1.8:1.4:0.2, respectively, while the three‐component blend lacked Z11‐14:Al. Pheromone emissions by groups of virgin females and commercial lures were collected in the laboratory and analysed by gas chromatography. These data were used to formulate a new pheromone lure that was compared to a commercial lure in a second trapping study. In the first field study, traps baited with 10 mg pheromones or above captured significantly more moths than traps baited with 1 mg or less, regardless of the blend. Surprisingly, groups of virgin females only emitted two detectable pheromone components, Z11‐14:Ac and Z11‐14:OH in a ratio of 37:63, which was substantially different from the blends detected in pheromone glands in the literature. The newly formulated pheromone lure based on females’ emission was more than twice as attractive as the commercial lure which emitted a 74:5:21 three‐component blend of Z11‐14:Ac, E11‐14:Ac and Z11‐14:OH. Our results suggested that the actual pheromones released by females may not translate directly to the content of pheromone glands.
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