Belowground carbon transfer across mycorrhizal networks among trees: Facts, not fantasy

The mycorrhizal symbiosis between fungi and plants is among the oldest, ubiquitous and most important interactions in terrestrial life on Earth. Carbon (C) transfer across a common mycorrhizal network (CMN) was demonstrated over half a century ago in the lab (Reid and Woods 1969), and later in the field (Simard et al. 1997). Recent years have seen ample progress in this research direction, including evidence for ecological significance of carbon transfer (Klein et al. 2016). Furthermore, specific cases where the architecture of mycorrhizal networks have been mapped (Beiler et al. 2015) and CMNC transfer from mature trees to seedlings has been demonstrated (Orrego 2018) have suggested that trees in forests are more connected than once thought (Simard 2021). In a recent Perspective, Karst et al. (2023) offered a valuable critical review warning of overinterpretation and positive citation bias in CMN research. It concluded that while there is evidence for C movement among plants, the importance of CMNs remains unclear, as noted by others too (Henriksson et al. 2023). Here we argue that while some of these claims are justified, factual evidence about belowground C transfer across CMNs is solid and accumulating

Preservation of DNA Privacy During the Large Scale Detection of COVID-19

As humanity struggles to contain the global COVID-19 pandemic, privacy concerns are emerging regarding confinement, tracing and testing. The scientific debate concerning privacy of the COVID-19 tracing efforts has been intense, especially focusing on the choice between centralised and decentralised tracing apps. The privacy concerns regarding COVID-19 testing, however, have not received as much attention even though the privacy at stake is arguably even higher. COVID-19 tests require the collection of samples. Those samples possibly contain viral material but inevitably also human DNA. Patient DNA is not necessary for the test but it is technically impossible to avoid collecting it. The unlawful preservation, or misuse, of such samples at a massive scale may hence disclose patient DNA information with far-reaching privacy consequences. Inspired by the cryptographic concept of "Indistinguishability under Chosen Plaintext Attack", this paper poses the blueprint of novel types of tests allowing to detect viral presence without leaving persisting traces of the patient's DNA. Authors are listed in alphabetical order.Comment: 10 pages, 1 figur

Forced and self-excited oscillations of an optomechanical cavity

We experimentally study forced and self oscillations of an optomechanical cavity which is formed between a fiber Bragg grating that serves as a static mirror and between a freely suspended metallic mechanical resonator that serves as a moving mirror. In the domain of small amplitude mechanical oscillations, we find that the optomechanical coupling is manifested as changes in the effective resonance frequency, damping rate and cubic nonlinearity of the mechanical resonator. Moreover, self oscillations of the micromechanical mirror are observed above a certain optical power threshold. A comparison between the experimental results and a theoretical model that we have recently presented yields a good agreement. The comparison also indicates that the dominant optomechanical coupling mechanism is the heating of the metallic mirror due to optical absorption.Comment: 11 pages, 6 figure

Impaired synaptic function is linked to cognition in Parkinson's disease

OBJECTIVE: Cognitive impairment is frequent in Parkinson's disease, but the underlying mechanisms are insufficiently understood. Because cortical metabolism is reduced in Parkinson's disease and closely associated with cognitive impairment, and CSF amyloid‐β species are reduced and correlate with neuropsychological performance in Parkinson's disease, and amyloid‐β release to interstitial fluid may be related to synaptic activity; we hypothesize that synapse dysfunction links cortical hypometabolism, reduced CSF amyloid‐β, and presynaptic deposits of α‐synuclein. We expect a correlation between hypometabolism, CSF amyloid‐β, and the synapse related‐markers CSF neurogranin and α‐synuclein. METHODS: Thirty patients with mild‐to‐moderate Parkinson's disease and 26 healthy controls underwent a clinical assessment, lumbar puncture, MRI, 18F‐fludeoxyglucose‐PET, and a neuropsychological test battery (repeated for the patients after 2 years). RESULTS: All subjects had CSF amyloid‐β 1‐42 within normal range. In Parkinson's disease, we found strong significant correlations between cortical glucose metabolism, CSF Aβ, α‐synuclein, and neurogranin. All PET CSF biomarker‐based cortical clusters correlated strongly with cognitive parameters. CSF neurogranin levels were significantly lower in mild‐to‐moderate Parkinson's disease compared to controls, correlated with amyloid‐β and α‐synuclein, and with motor stage. There was little change in cognition after 2 years, but the cognitive tests that were significantly different, were also significantly associated with cortical metabolism. No such correlations were found in the control group. INTERPRETATION: CSF Aβ, α‐synuclein, and neurogranin concentrations are related to cortical metabolism and cognitive decline. Synaptic dysfunction due to Aβ and α‐synuclein dysmetabolism may be central in the evolution of cognitive impairment in Parkinson's disease

Behavioural responses of Anopheles gambiae sensu stricto M and S molecular form larvae to an aquatic predator in Burkina Faso

Background: Predation of aquatic immature stages has been identified as a major evolutionary force driving habitat segregation and niche partitioning in the malaria mosquito Anopheles gambiae sensu stricto in the humid savannahs of Burkina Faso, West Africa. Here, we explored behavioural responses to the presence of a predator in wild populations of the M and S molecular forms of An. gambiae that typically breed in permanent (e.g., rice field paddies) and temporary (e.g., road ruts) water collections. Methods: Larvae used in these experiments were obtained from eggs laid by wild female An. gambiae collected from two localities in south-western Burkina Faso during the 2008 rainy season. Single larvae were observed in an experimental arena, and behavioural traits were recorded and quantified a) in the absence of a predator and b) in the presence of a widespread mosquito predator, the backswimmer Anisops jaczewskii. Differences in the proportion of time allocated to each behaviour were assessed using Principal Component Analysis and Multivariate Analysis of Variance. Results: The behaviour of M and S form larvae was found to differ significantly; although both forms mainly foraged at the water surface, spending 60-90% of their time filtering water at the surface or along the wall of the container, M form larvae spent on average significantly more time browsing at the bottom of the container than S form larvae (4.5 vs. 1.3% of their overall time, respectively; P < 0.05). In the presence of a predator, larvae of both forms modified their behaviour, spending significantly more time resting along the container wall (P < 0.001). This change in behaviour was at least twice as great in the M form (from 38.6 to 66.6% of the time at the wall in the absence and presence of the predator, respectively) than in the S form (from 48.3 to 64.1%). Thrashing at the water surface exposed larvae to a significantly greater risk of predation by the notonectid (P < 0.01), whereas predation occurred significantly less often when larvae were at the container wall (P < 0.05) and might reflect predator vigilance. Conclusions: Behavioural differences between larvae of the M and S form of An. gambiae in response to an acute predation risk is likely to be a reflection of different trade-offs between foraging and predator vigilance that might be of adaptive value in contrasting aquatic ecosystems. Future studies should explore the relevance of these findings under the wide range of natural settings where both forms co-exist in Africa

Biocontrol of larval mosquitoes by Acilius sulcatus (Coleoptera: Dytiscidae)

<p>Abstract</p> <p>Background</p> <p>Problems associated with resistant mosquitoes and the effects on non-target species by chemicals, evoke a reason to find alternative methods to control mosquitoes, like the use of natural predators. In this regard, aquatic coleopterans have been explored less compared to other insect predators. In the present study, an evaluation of the role of the larvae of <it>Acilius sulcatus </it>Linnaeus 1758 (Coleoptera: Dytiscidae) as predator of mosquito immatures was made in the laboratory. Its efficacy under field condition was also determined to emphasize its potential as bio-control agent of mosquitoes.</p> <p>Methods</p> <p>In the laboratory, the predation potential of the larvae of <it>A. sulcatus </it>was assessed using the larvae of <it>Culex quinquefasciatus </it>Say 1823 (Diptera: Culicidae) as prey at varying predator and prey densities and available space. Under field conditions, the effectiveness of the larvae of <it>A. sulcatus </it>was evaluated through augmentative release in ten cemented tanks hosting immatures of different mosquito species at varying density. The dip density changes in the mosquito immatures were used as indicator for the effectiveness of <it>A. sulcatus </it>larvae.</p> <p>Results</p> <p>A single larva of <it>A. sulcatus </it>consumed on an average 34 IV instar larvae of <it>Cx. quinquefasciatus </it>in a 24 h period. It was observed that feeding rate of <it>A. sulcatus </it>did not differ between the light-on (6 a.m. – 6 p.m.), and dark (6 p.m. – 6 a.m.) phases, but decreased with the volume of water i.e., space availability. The prey consumption of the larvae of <it>A. sulcatus </it>differed significantly (P < 0.05) with different prey, predator and volume combinations, revealed through univariate ANOVA. The field study revealed a significant decrease (p < 0.05) in larval density of different species of mosquitoes after 30 days from the introduction of <it>A. sulcatus </it>larvae, while with the withdrawal, a significant increase (p < 0.05) in larval density was noted indicating the efficacy of <it>A. sulcatus </it>in regulating mosquito immatures. In the control tanks, mean larval density did not differ (p > 0.05) throughout the study period.</p> <p>Conclusion</p> <p>the larvae of the dytiscid beetle <it>A. sulcatus </it>proved to be an efficient predator of mosquito immatures and may be useful in biocontrol of medically important mosquitoes.</p