The Ubiquitin Conjugating Enzyme UbcD1 is Required for Notch Signaling Activation During Drosophila Wing Development

Aphid gene expression following polerovirus acquisition is host species dependent

Upon acquisition of persistent circulative viruses such as poleroviruses, the virus particles transcytose through membrane barriers of aphids at the midgut and salivary glands via hemolymph. Such intricate interactions can influence aphid behavior and fitness and induce associated gene expression in viruliferous aphids. Differential gene expression can be evaluated by omics approaches such as transcriptomics. Previously conducted aphid transcriptome studies used only one host species as the source of virus inoculum. Viruses typically have alternate hosts. Hence, it is not clear how alternate hosts infected with the same virus isolate alter gene expression in viruliferous vectors. To address the question, this study conducted a transcriptome analysis of viruliferous aphids that acquired the virus from different host species. A polerovirus, cotton leafroll dwarf virus (CLRDV), which induced gene expression in the cotton aphid, Aphis gossypii Glover, was assessed using four alternate hosts, viz., cotton, hibiscus, okra, and prickly sida. Among a total of 2,942 differentially expressed genes (DEGs), 750, 310, 1,193, and 689 genes were identified in A. gossypii that acquired CLRDV from infected cotton, hibiscus, okra, and prickly sida, respectively, compared with non-viruliferous aphids that developed on non-infected hosts. A higher proportion of aphid genes were overexpressed than underexpressed following CLRDV acquisition from cotton, hibiscus, and prickly sida. In contrast, more aphid genes were underexpressed than overexpressed following CLRDV acquisition from okra plants. Only four common DEGs (heat shock protein, juvenile hormone acid O-methyltransferase, and two unannotated genes) were identified among viruliferous aphids from four alternate hosts. Gene ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) annotations indicated that the acquisition of CLRDV induced DEGs in aphids associated with virus infection, signal transduction, immune systems, and fitness. However, these induced changes were not consistent across four alternate hosts. These data indicate that alternate hosts could differentially influence gene expression in aphids and presumably aphid behavior and fitness despite being infected with the same virus isolate.

Notch Signaling in Insect Development: A Simple Pathway with Diverse Functions

Notch signaling is an evolutionarily conserved pathway which functions between adjacent cells to establish their distinct identities. Despite operating in a simple mechanism, Notch signaling plays remarkably diverse roles in development to regulate cell fate determination, organ growth and tissue patterning. While initially discovered and characterized in the model insect Drosophila melanogaster, recent studies across various insect species have revealed the broad involvement of Notch signaling in shaping insect tissues. This review focuses on providing a comprehensive picture regarding the roles of the Notch pathway in insect development. The roles of Notch in the formation and patterning of the insect embryo, wing, leg, ovary and several specific structures, as well as in physiological responses, are summarized. These results are discussed within the developmental context, aiming to deepen our understanding of the diversified functions of the Notch signaling pathway in different insect species.

Differential Transcriptional Responses in Two Old World Bemisia tabaci Cryptic Species Post Acquisition of Old and New World Begomoviruses

Begomoviruses are transmitted by several cryptic species of the sweetpotato whitefly, Bemisia tabaci (Gennadius), in a persistent and circulative manner. Upon virus acquisition and circulative translocation within the whitefly, a multitude of molecular interactions occur. This study investigated the differentially expressed transcript profiles associated with the acquisition of the Old World monopartite begomovirus, tomato yellow leaf curl virus (TYLCV), and two New World bipartite begomoviruses, sida golden mosaic virus (SiGMV) and cucurbit leaf crumple virus (CuLCrV), in two invasive B. tabaci cryptic species, Middle East-Asia Minor 1 (MEAM1) and Mediterranean (MED). A total of 881 and 559 genes were differentially expressed in viruliferous MEAM1 and MED whiteflies, respectively, compared with their non-viruliferous counterparts, of which 146 genes were common between the two cryptic species. For both cryptic species, the number of differentially expressed genes (DEGs) associated with TYLCV and SiGMV acquisition were higher compared with DEGs associated with CuLCrV acquisition. Pathway analysis indicated that the acquisition of begomoviruses induced differential changes in pathways associated with metabolism and organismal systems. Contrasting expression patterns of major genes associated with virus infection and immune systems were observed. These genes were generally overexpressed and underexpressed in B. tabaci MEAM1 and MED adults, respectively. Further, no specific expression pattern was observed among genes associated with fitness (egg production, spermatogenesis, and aging) in viruliferous whiteflies. The weighted gene correlation network analysis of viruliferous B. tabaci MEAM1 and MED adults identified different hub genes potentially implicated in the vector competence and circulative tropism of viruses. Taken together, the results indicate that both vector cryptic species and the acquired virus species could differentially affect gene expression.