Biology subjects

You, M.

Publications and source records attributed to You, M..

26 records · Page 2Linked to original sources

bioRxiv2022

Small silencing RNAs expressed from W-linked retrocopies of Masculinizer target the male-determining gene PxyMasc during female sex determination in the Diamondback moth Plutella xylostella

The Lepidoptera are an insect order of cultural, economic and environmental importance, representing c. 10% of all described living species. Yet, for all but one of these species (silkmoth, Bombyx mori) the molecular genetics of how sexual fate is determined remains unknown. We investigated this in the diamondback moth (DBM - Plutella xylostella), a globally important, highly invasive and economically damaging pest of cruciferous crops. Our previous work uncovered a regulator of male sex determination in DBM - PxyMasc, a homologue of B. mori Masculinizer - which although initially expressed in embryos of both sexes, is then reduced in female embryos, leading to female-specific splicing of doublesex. Here, through sequencing small RNA libraries generated from early embryos and sexed larval pools, we identified a variety of small silencing RNAs (predominantly piRNAs) complementary to PxyMasc, whose temporal expression correlated with the reduction in PxyMasc transcript observed previously in females. Analysis of these small RNAs showed that they are expressed from tandemly-arranged, multi-copy arrays found exclusively on the W (female-specific) chromosome, which we term Pxyfem. Analysis of the Pxyfem sequences showed that they are partial cDNAs of PxyMasc mRNA transcripts, likely integrated into transposable element graveyards by the non-canonical action of retrotransposons (retrocopies), and that their apparent similarity to B. mori feminizer more probably represents convergent evolution. Our study helps elucidate the sex determination cascade in this globally important pest and highlights the shortcuts which retrotransposition events can facilitate in the evolution of complex molecular cascades, including sex determination. Significance statementUncovering the mechanisms which species have evolved to determine sex is of fundamental interest and provides avenues for pest management through genetic manipulation of these pathways. In insects, much of what is known regarding sex determination is concentrated within the Diptera and Hymenoptera, despite other orders (e.g. Lepidoptera) being of great ecological and economic importance. Here, using small RNA sequencing of embryonic and early larval samples, we uncover an RNAi-based sex determination system which silences the male determining gene PxyMasc in the Diamondback moth (Plutella xylostella) - a global pest of cruciferous crops. We track production of these silencing RNAs back to the W-chromosome where they are expressed from partial cDNA copies of PxyMasc. Our analysis suggests these are PxyMasc retrocopies, integrated via the non-canonical action of LTR retrotransposons and that similarities between this system and the feminizer system in Bombyx mori likely represent convergent evolution.

developmental biology↗

bioRxiv2021

Genomic variation in the tea leafhopper reveals the basis of adaptive evolution

The tea green leafhopper (TGL), Empoasca onukii, is of biological and economic interest. Despite numerous studies, the mechanisms underlying its adaptation and evolution remain enigmatic. Here, we used previously untapped genome and population genetics approaches to examine how this pest so rapidly has adapted to different environmental variables and thus has expanded geographically. We complete a chromosome-level assembly and annotation of the E. onukii genome, showing notable expansions of gene families associated with adaptation to chemoreception and detoxification. Genomic signals indicating balancing selection highlight metabolic pathways involved in adaptation to a wide range of tea varieties grown across ecologically diverse regions. Patterns of genetic variation among 54 E. onukii samples unveil the population structure and evolutionary history across different tea-growing regions in China. Our results demonstrate that the genomic change in key pathways, including those linked to metabolism, circadian rhythms and immune system function, may underlie the successful spread and adaptation of E. onukii. This work highlights the genetic and molecular bases underlying the evolutionary success of a species with broad economic impact, and provides insight into insect adaptation to host plants, which will ultimately facilitate more sustainable pest management.

genomics↗

bioRxiv2021

Towards CRISPR/Cas9-based gene drive in the diamondback moth Plutella xylostella

Promising to provide powerful genetic control tools, gene drives have been constructed in multiple dipterans, yeast and mice, for the purposes of population elimination or modification. However, it remains unclear whether these techniques can be applied to lepidopterans. Here, we used endogenous regulatory elements to drive Cas9 and sgRNA expression in the diamondback moth, (Plutella xylostella), and test the first split-drive system in a lepidopteran. The diamondback moth is an economically important global agriculture pest of cruciferous crops and has developed severe resistance to various insecticides, making it a prime candidate for such novel control strategy development. A very high level of somatic editing was observed in Cas9/sgRNA transheterozygotes, although no significant homing was revealed in the subsequent generation. Although heritable, Cas9-medated germline cleavage, as well as maternal and paternal Cas9 deposition was observed, rates were far lower than for somatic cleavage events, indicating robust somatic but limited germline activity of Cas9/sgRNA under the control of selected regulatory elements. Our results provide valuable experience, paving the way for future construction of gene drive-based genetic control strategies in DBM or other lepidopterans.

genetics↗

bioRxiv2021

Live-Cell Imaging of (p)ppGpp with RNA-based Fluorescent Sensors

Guanosine tetra- and pentaphosphate, (p)ppGpp, are important alarmone nucleotides that regulate bacterial survival in stressful environment. A direct detection of (p)ppGpp in living cells is critical for our understanding of the mechanism of bacterial stringent response. However, it is still challenging to directly image and measure cellular (p)ppGpp. Here, we report a type of RNA-based fluorescent sensors for live-cell imaging of (p)ppGpp. Our sensor is engineered by conjugating a recently identified (p)ppGpp-specific riboswitch with a fluorogenic RNA aptamer, Broccoli. These sensors can be genetically encoded and enable direct monitoring of cellular (p)ppGpp accumulation. Unprecedented information on cell-to-cell variation and cellular dynamics of (p)ppGpp levels can now be obtained under different nutritional conditions. We predict that these RNA-based sensors will be broadly adapted to study bacterial stringent response.

cell biology↗

bioRxiv2021

Mass cytometry reveals immunological response to radiation-induced cardiac fibrosis in mice

BackgroundRadiation-induced cardiac injury results in complex clinical presentations, unique management issues, and increased morbidity and mortality. But the underlying mechanism of radiation-induced cardiac injury is still unclear. The aim of this study is to explain the compositional alterations of innate and adaptive cells after thoracic irradiation and the relationship of macrophage with other adaptive cells. MethodsC57BL/6 mice were anesthetized and performed with 20Gy single dose cardiac irradiation. We carried out mice echocardiography to examine cardiac function. Masson and immunohistochemical staining were adopted to analyze cardiac fibrosis. Blood and cardiac tissue were collected 7 days, 4 weeks and 8 weeks after irradiation and sham-irradiated mice were set as a control group. Part of blood and tissue samples were analyzed with mass cytometry. We also used remaining blood samples to measure pro-fibrotic cytokines. ResultsWe observed reduced cardiac diastolic function and pathologically confirmed cardiac fibrosis after thoracic irradiation. Through mass cytometry, we identified that the proportion of neutrophils, macrophages and monocytes elevated. The ratio of T and B cells decreased after irradiation in the blood samples. For tissue samples, the proportion of macrophages, monocytes and neutrophils increased, endothelial cells reduced, but T and B cells also increased. The level of TGF-{beta}, TNF-, IL-6 climbed considerably, all of them are closely associated with the evolution of macrophage function during recovering phase of cardiac injury. In the correlation plot, we also discovered that CD4+T and CD8+T cells were strongly positively correlated with macrophages. ConclusionWe illustrated the immunological response after radiation-induced cardiac fibrosis, and macrophage may play a crucial role during the process. The results might have therapeutic potential for targeting macrophages in order to reduce radiation-induced cardiac fibrosis.

cancer biology↗

bioRxiv2021

Landscape composition mediates suppression of major pests by natural enemies in conventional cruciferous vegetables

BackgroundConservation biological control provides an environment-friendly approach to improve the efficacy of natural enemies. Although numerous studies have demonstrated the potential of semi-natural habitats in promoting biological control in organic or unsprayed agroecosystems, few studies were conducted in conventional agricultural fields. In this study, we investigated the effects of landscape composition on the major pests of cruciferous vegetables and on the assemblages of their natural enemies in southeastern China. ResultsHabitat diversity, particularly increasing grassland proportion in the landscape, had a positive impact in controlling both small-sized pests (aphids, leaf miners, thrips and flea beetles) and Plutella xylostella. This increasing proportion also promoted greater abundance and diversity of canopy-dwelling predators, more forests supported a higher diversity of airborne enemies (parasitoids and canopy-dwelling predators) as well as a higher abundance of ground-dwelling predators. A general increase in habitat diversity was beneficial to parasitoids and ground-dwelling predators. Additionally, the proportion of forest, grassland, and non-cruciferous vegetable area, as well as habitat diversity, affected the compositions of natural enemy communities. Moreover, inconsistent effects of non-cruciferous and grassland habitats were found between sampling regions for small-sized pests and canopy-dwelling predators. Moreover, the scale at which pests and natural enemies abundance and richness responded most to landscape composition varied with their feeding range and dispersal ability. ConclusionOur study provides evidence that increasing the amount of semi-natural habitats and habitat diversity can result in lower pest and higher natural enemy abundance in conventional cruciferous agroecosystems. Regional conditions and spatial scales also should be considered in designing the agricultural landscape mosaic.

ecology↗

bioRxiv2020

A comparative analysis reveals irreproducibility in searches of scientific literature

Repeatability is the cornerstone of science and it is particularly important for systematic reviews. However, little is known on how database and search engine choices influence replicability. Here, we present a comparative analysis of time-synchronized searches at different locations in the world, revealing a large variation among the hits obtained within each of the several search terms using different search engines. We found that PubMed and Scopus returned geographically consistent results to identical search strings, Google Scholar and Web of Science varied substantially both in the number of returned hits and in the list of individual articles depending on the search location and computing environment. To maintain scientific integrity and consistency, especially in systematic reviews, action is needed from both the scientific community and scientific search platforms to increase search consistency. Researchers are encouraged to report the search location, and database providers should make search algorithms transparent and revise access rules to titles behind paywalls.View Full Text

scientific communication and education↗

bioRxiv2020

Quantifying Tensile Forces at Cell-Cell Junctions with a DNA-based Fluorescent Probe

Cells are physically contacting with each other. Direct and precise quantification of forces at cell-cell junctions is still challenging. Herein, we have developed a DNA-based ratiometric fluorescent probe, termed DNAMeter, to quantify intercellular tensile forces. These lipid-modified DNAMeters can spontaneously anchor onto live cell membranes. The DNAMeter consists of two self-assembled DNA hairpins of different force tolerance. Once the intercellular tension exceeds the force tolerance to unfold a DNA hairpin, a specific fluorescence signal will be activated, which enables the real-time imaging and quantification of tensile forces. Using E-cadherin-modified DNAMeter as an example, we have demonstrated an approach to quantify, at the molecular level, the magnitude and distribution of E-cadherin tension among epithelial cells. Compatible with readily accessible fluorescence microscopes, these easy-to-use DNA tension probes can be broadly used to quantify mechanotransduction in collective cell behaviors.

biophysics↗