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1. MicroRNA Expression Prior to Biting in a Vector Mosquito Anticipates Physiological Processes Related to Energy Utilization, Reproduction and Immunity

   https://doi.org/10.3390/insects14080700  

   Marzec, Sarah; Siperstein, Alden; Zhou, Angela; Holzapfel, Christina; Bradshaw, William; Meuti, Megan; Armbruster, Peter (August 2023, Insects)

   Understanding the molecular and physiological processes underlying biting behavior in vector mosquitoes has important implications for developing novel strategies to suppress disease transmission. Here, we conduct small-RNA sequencing and qRT-PCR to identify differentially expressed microRNAs (miRNAs) in the head tissues of two subspecies of Culex pipiens that differ in biting behavior and the ability to produce eggs without blood feeding. We identified eight differentially expressed miRNAs between biting C. pipiens pipiens (Pipiens) and non-biting C. pipiens molestus (Molestus); six of these miRNAs have validated functions or predicted targets related to energy utilization (miR8-5-p, miR-283, miR-2952-3p, miR-1891), reproduction (miR-1891), and immunity (miR-2934-3p, miR-92a, miR8-5-p). Although miRNAs regulating physiological processes associated with blood feeding have previously been shown to be differentially expressed in response to a blood meal, our results are the first to demonstrate differential miRNA expression in anticipation of a blood meal before blood is actually imbibed. We compare our current miRNA results to three previous studies of differential messenger RNA expression in the head tissues of mosquitoes. Taken together, the combined results consistently show that biting mosquitoes commit to specific physiological processes in anticipation of a blood meal, while non-biting mosquitoes mitigate these anticipatory costs. 

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2. Conserved molecular pathways underlying biting in two divergent mosquito genera

   https://doi.org/10.1111/eva.13379  

   Alden Siperstein; Sarah Marzec; Megan L. Fritz; Christina M. Holzapfel; William E. Bradshaw; Peter A. Armbruster; Megan E. Meuti (April 2022, Evolutionary applications)

   Mosquitoes transmit a wide variety of devastating pathogens when they bite vertebrate hosts and feed on their blood. However, three entire mosquito genera and many individual species in other genera have evolved a nonbiting life history in which blood is not required to produce eggs. Our long-term goal is to develop novel interventions that reduce or eliminate the biting behavior in vector mosquitoes. A previous study used biting and nonbiting populations of a nonvector mosquito, Wyeomyia smithii, as a model to uncover the transcriptional basis of the evolutionary transition from a biting to a nonbiting life history. Herein, we ask whether the molecular pathways that were differentially expressed due to differences in biting behavior in W. smithii are also differentially expressed between subspecies of Culex pipiens that are obligate biting (Culex pipiens pipiens) and facultatively nonbiting (Culex pipiens molestus). Results from RNAseq of adult heads show dramatic upregulation of transcripts in the ribosomal protein pathway in biting C. pipiens, recapitulating the results in W. smithii, and implicating the ancient and highly conserved ribosome as the intersection to understanding the evolutionary and physiological basis of blood feeding in mosquitoes. Biting Culex also strongly upregulate energy production pathways, including oxidative phosphorylation and the citric acid (TCA) cycle relative to nonbiters, a distinction that was not observed in W. smithii. Amino acid metabolism pathways were enriched for differentially expressed genes in biting versus nonbiting Culex. Relative to biters, nonbiting Culex upregulated sugar metabolism and transcripts contributing to reproductive allocation (vitellogenin and cathepsins). These results provide a foundation for developing strategies to determine the natural evolutionary transition between a biting and nonbiting life history in vector mosquitoes. 

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3. Cell Cycle-dependent Regulation and Function of ARGONAUTE1 in Plants

   https://doi.org/10.1105/tpc.19.00069  

   Trolet, Adrien; Baldrich, Patricia; Criqui, Marie-Claire; Dubois, Marieke; Clavel, Marion; Meyers, Blake C.; Genschik, Pascal (August 2019, The Plant Cell)

   Regulated gene expression is key to the orchestrated progression of the cell cycle. Many genes are expressed at specific points in the cell cycle, including important cell cycle regulators, plus factors involved in signal transduction, hormonal regulation and metabolic control. We demonstrate that post-embryonic depletion of Arabidopsis thaliana ARGONAUTE1 (AGO1), the main effector of plant microRNAs, impairs cell division in the root meristem. We utilized the highly synchronizable tobacco (Nicotiana tabacum) BY2 cell suspension to analyze mRNA, small RNAs, and mRNA cleavage products of synchronized BY2 cells at S, G2, M and G1 phases of the cell cycle. This revealed that in plants, only a few miRNAs show differential accumulation during the cell cycle, and miRNA-target pairs were only identified for a small proportion of the more than 13,000 differentially expressed genes during the cell cycle. However, this unique set of microRNA-target pairs could be key to attenuate the expression of several transcription factors and disease resistance genes. We also demonstrate that AGO1 binds to a set of 19 nt, tRNA-derived fragments during the cell cycle progression. 

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4. A conserved trans regulatory loop involving an odorant binding protein controls male mating behavior in flies

   https://doi.org/10.1101/2021.06.22.447776  

   Delclos, Pablo J; Adhikari, Kiran; Hassan, Oluwatomi; Oderhowho, Alexander A; Sriskantharajah, Vyshnika; Trinh, Tammie; Meisel, Richard P (January 2021, bioRxiv)

   A major goal in evolutionary biology is to understand how natural variation is maintained in sexually selected and sexually dimorphic traits. Hypotheses to explain genetic variation in sexually selected traits include context-dependent fitness effects, epistatic interactions, and pleiotropic constraints. The house fly, Musca domestica, is a promising system to investigate how these factors affect polymorphism in sexually selected traits. Two common Y chromosomes (YM and IIIM) segregate as stable polymorphisms in natural house fly populations, appear to be locally adapted to different thermal habitats, and differentially affect male mating success. Here, we perform a meta-analysis of RNA-seq data which identifies genes encoding odorant binding proteins (in the Obp56h family) as differentially expressed between the heads of males carrying YM and IIIM Differential expression of Obp56h has been associated with variation in male mating behavior in Drosophila melanogaster. We find differences in male mating behavior between house flies carrying the Y chromosomes that are consistent with the relationship between male mating behavior and expression of Obp56h in D. melanogaster. We also find that male mating behaviors in house fly are affected by temperature, and the same temperature differentials further affect the expression of Obp56h genes. However, we show that temperature-dependent effects cannot explain the maintenance of genetic variation for male mating behavior in house fly. Using a network analysis and allele-specific expression measurements, we find evidence that the house fly IIIM chromosome is a trans regulator of Obp56h gene expression. Moreover, we find that Obp56h disproportionately affects the expression of genes on the D. melanogaster chromosome that is homologous to the house fly IIIM chromosome. This provides evidence for a conserved trans regulatory loop involving Obp56h expression that affects male mating behavior in flies. The complex regulatory architecture controlling Obp56h expression suggests that variation in male mating behavior could be maintained by epistasis or pleiotropic constraints. 

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5. Different transcriptional responses to developmental versus short-term acclimation temperatures in Pieris rapae

   https://doi.org/10.1101/2025.11.11.686846  

   Sturiale, Samantha L; He, Lorrie_Le Yi; Malinski, Katherine H; Willett, Christopher S; Kingsolver, Joel G; Ries, Leslie; Armbruster, Peter A (November 2025, bioRxiv)

   ABSTRACT To anticipate the role of thermal plasticity in evolutionary responses to climate change, it is critical to identify the molecular processes which underlie responses to temperature across different timescales. However, existing transcriptomic studies largely focus on responses to acute thermal stress or do not manipulate temperature across multiple timescales. We used RNA-sequencing to measure gene expression ofPieris rapaelarvae exposed to a full factorial combination of non-stressful high and low temperatures across a long-term developmental timescale and a short-term acclimation timescale. This study design allowed us to separate genes associated with developmental thermal plasticity versus short-term acclimation responses, respectively. We observed that few genes were differentially expressed in response to both developmental temperature and short-term acclimation temperature, though there were some functional similarities across the two gene sets. This result suggests that the expression of different genes underlies thermal plasticity acting on different timescales, and thus these responses may evolve independently. Genes responsive to developmental temperature include those related to hormone activity and cold acclimation, while short-term acclimation temperature affected the expression of several cuticle protein genes. Both developmental and short-term acclimation temperature treatments affected the expression of genes involved in detoxification and protein folding. Finally, we identified a small subset of genes for which expression levels were dependent on the interaction between developmental and short-term acclimation temperature treatments, providing possible mechanisms by which developmental temperature may affect an organism’s capacity for acclimation responses later in life. 

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