Integrated miRNA and transcriptome profiling to explore the molecular determinism of convergent adaptation to corn in two lepidopteran pests of agriculture

BackgroundThe degree to which adaptation to same environment is determined by similar molecular mechanisms, is a topic of broad interest in evolutionary biology, as an indicator of evolutionary predictability. We wished to address if adaptation to the same host plant in phytophagous insects involved related gene expression patterns. We compared sRNA-Seq and RNA-Seq data between two pairs of taxa of Ostrinia and Spodoptera frugiperda sharing maize as host-plant. For the latter, we had previously carried out a reciprocal transplant experiment by feeding of the larvae of the Corn strain (Sf-C) and the Rice strain (Sf-R) on corn versus rice and characterized the mRNA and miRNA responses.ResultsFirst, we predicted the genes encoding miRNA in Ostrinia nubilalis (On) and O. scapulalis (Os). Respectively 67 and 65 known miRNA genes, as well as 196 and 190 novel ones were predicted with Os genome using sncRNAs extracted from whole larvae feeding on corn or mugwort. In On, a read counts analysis showed that 37 (55.22%) known miRNAs and 19 (9.84%) novel miRNAs were differentially expressed (DE) on mugwort compared to corn (in Os, 25 known miRs (38.46%) and 8 novel ones (4.34%)). Between species on corn, 8 (12.5%) known miRNAs and 8 (6.83%) novel ones were DE while only one novel miRNA showed expression variation between species on mugwort. Gene target prediction led to the identification of 2953 unique target genes in On and 2719 in Os, among which 11.6% (344) were DE when comparing species on corn. 1.8% (54) of On miR targets showed expression variation upon a change of host-plant.We found molecular changes matching convergent phenotype, i.e., a set of nine miRNAs that are regulated either according to the host-plant both in On and Sf-C or between them on the same plant, corn. Among DE miR target genes between taxa, 13.7% shared exactly the same annotation between the two pairs of taxa and had function related to insect host-plant interaction.ConclusionThere is some similarity in underlying genetic mechanisms of convergent evolution of two distant Lepidopteran species having adopted corn in their host range, highlighting possible adaptation genes

Evaluation of Dual Side Cooling System for Prismatic Batteries for Vehicle Aplications

Today lithium-ion stands out among the various battery technologies in vehicle applications thanks to their good energy density, low self-discharge and the absence of the memory effect. Nevertheless, lithium-ion batteries pose many challenges such as driving range, lifespan, safety issues and also the charging time which is still significant. In order to reduce the charging time, it is necessary to inject a very high current into the battery which may drastically raise its temperature and thus reduce its lifespan. Today, in most cases, the battery pack of an electric vehicle is cooled through flat cooling plates, mounted either by the lateral or the bottom surfaces. These cooling plates can also be used to warm up the battery in cold weather. But during the fast charge, this configuration poses some problems and can be not efficient enough to cool or heat the batteries. In this study, a battery module is thermally managed not only by the bottom cooling plate but also by a second cooling plate placed on the busbars. According to simulations and experimental tests regarding one case study, this configuration makes it possible to not only cool the module more quickly by reducing the thermal time constant by 47% but also reduces the battery maximum pick temperature reached with a conventional cooling system by 6°C. It stands out that the top cooling plate acts like a thermal bridge which unifies the temperature inside the battery module and thus support the equal ageing process of the batteries

Specialization to the host plant in Lepidoptera pests: pattern and process

Specialization to the host plant in Lepidoptera pests: pattern and process. XVth ESEB Meetin

Detection and Genetic Characterization of Puumala Orthohantavirus S-Segment in Areas of France Non-Endemic for Nephropathia Epidemica

International audiencePuumala virus (PUUV) in Europe causes nephropathia epidemica (NE), a mild form of hemorrhagic fever with renal syndrome (HFRS). The incidence of NE is highly heterogeneous spatially, whereas the geographic distribution of the wild reservoir of PUUV, the bank vole, is essentially homogeneous. Our understanding of the processes driving this heterogeneity remains incomplete due to gaps in knowledge. Little is known about the current distribution and genetic variation of PUUV in the areas outside the well-identified zones of NE endemicity. We trapped bank voles in four forests in French regions in which NE is considered non-endemic, but sporadic NE cases have been reported recently. We tested bank voles for anti-PUUV IgG and characterized the S segment sequences of PUUV from seropositive animals. Phylogenetic analyses revealed specific amino-acid signatures and genetic differences between PUUV circulating in non-endemic and nearby NE-endemic areas. We also showed, in temporal surveys, that the amino-acid sequences of PUUV had undergone fewer recent changes in areas non-endemic for NE than in endemic areas. The evolutionary history of the current French PUUV clusters was investigated by phylogeographic approaches, and the results were considered in the context of the history of French forests. Our findings highlight the need to monitor the circulation and genetics of PUUV in a larger array of bank vole populations, to improve our understanding of the risk of NE

Transcriptional differences between the two host strains of Spodoptera frugiperda (Lepidoptera: Noctuidae)

International audienceSpodoptera frugiperda, the fall armyworm (FAW), is an important agricultural pest in the Americas and an emerging pest in sub-Saharan Africa, India, East-Asia and Australia, causing damage to major crops such as corn, sorghum and soybean. While FAW larvae are considered polyphagous, differences in diet preference have been described between two genetic variants: the corn strain (sf-C) and the rice strain (sf-R). These two strains are sometimes considered as distinct species, raising the hypothesis that host plant specialization might have driven their divergence. To test this hypothesis, we first performed controlled reciprocal transplant (RT) experiments to address the impact of plant diet on several traits linked to the fitness of the sf-C and sf-R strains. The phenotypical data suggest that sf-C is specialized to corn. We then used RNA-Se to identify constitutive transcriptional differences between strains, regardless of diet, in laboratory as well as in natural populations. We found that variations in mitochondrial transcription levels are among the most substantial and consistent differences between the two strains. Since mitochondrial genotypes also vary between the strains, we believe the mitochondria may have a significant role in driving strain divergence

Transcriptional plasticity evolution in two strains of Spodoptera frugiperda (Lepidoptera: Noctuidae) feeding on alternative host-plants

Spodoptera frugiperda, the fall armyworm (FAW), is an important agricultural pest in the Americas and an emerging pest in sub-Saharan Africa, causing damage to major crops such as corn, sorghum and soybean. While FAW larvae are considered polyphagous, differences in diet preference have been described between two genetic variants: the Corn strain (sf-C) and the Rice strain (sf-R). These two strains are sometimes considered as distinct species, raising the hypothesis that host plant specialization might have driven their divergence. Ecological speciation takes place when the selection of divergent traits leads to the reproductive isolation of two populations. Under this hypothesis, we expect that the transcriptional response to the host plants should affect differently the fitness of the two FAW strains. We also expect that these genes should also be linked to a reproductive isolation mechanism between the strains. In this study, we performed controlled reciprocal transplant (RT) experiments to address the impact of plant diet on several traits linked to the fitness of the sf-C and sf-R strains. The phenotypical data suggest that sf-C is specialized to corn. We then used RNA-Seq to analyze the gene expression of FAW larvae from RT experiments. We show that each strain has a different response to the same plant diets. However, we also found constitutive transcriptional differences between strains in laboratory and in natural populations. In particular, we show that mitochondrial transcription is the main difference between strains. A difference in mitochondrial function may be the basis for a shift in host plant and could be involved in hybrid incompatibility, raising the hypothesis that mitochondrial genome is the main target of selection between the two strains