Browsing by Author "Lu, Yong"
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Item Establishment of molecular genetic approaches to study gene expression and function in an invasive hemipteran, Halyomorpha halys(Springer Nature, 2017-10-18) Lu, Yong; Chen, Mengyao; Reding, Katie; Pick, LeslieHemiptera is a large clade of insects understudied in terms of developmental biology. Halyomorpha halys, the Brown Marmorated Stink Bug (BMSB, referred to throughout as H. halys), is an invasive hemipteran pest of the mid-Atlantic region of the USA that has rapidly spread to other regions in recent years, devastating a wide range of crops using a piercing and sucking mechanism. Its phylogenetic position, polyphagous habits, and rapid spread in the USA suggested that H. halys would be an ideal system to broaden our knowledge of developmental mechanisms in insects. We and others previously generated transcriptome sequences from different life stages of this insect. Here, we describe tools to examine gene expression patterns in whole-mount H. halys embryos and to test the response of H. halys to RNA interference (RNAi). We show that spatial and temporal patterns of gene expression in H. halys can be effectively monitored by both immunostaining and in situ hybridization. We also show that delivery of dsRNA to adult females knocks down gene function in offspring, using the homeotic gene Sex combs reduced (Scr). Knockdown of Hh-Scr resulted in dramatic malformations of the mouthparts, demonstrating for the first time that RNAi is effective in this species. Our results suggest that, despite difficulties with long-term laboratory culture of H. halys, this species shows promise as a developmental system.Item Evolution of Pair-rule genes(2015) Lu, Yong; Pick, Leslie; Cell Biology & Molecular Genetics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)All insects have a segmented body. The genes controlling segment development have been well characterized in the fruit fly, Drosophila melanogaster. These genes were divided into three categories: gap genes specify several continuous segments over a broad region of the embryo; Pair-Rule Genes (PRG) are responsible for segment formation and are the first set of genes to be expressed in repetitive patterns in the embryo; Segment polarity genes define anterior and posterior polarities within each segment.To understand how PRGs evolve, I took a comparative approach in this thesis. First, I compared the function of the Drosophila PRG ftz-f1 to that of its mammalian orthologs by expressing them all in Drosophila embryos. I found that the molecular function of this family of nuclear receptors has been highly conserved during evolution. Next, I set out to establish new insect model systems to study PRG function. While, some PRGs have been studied in other insects, most of these studies focused on holometabolous insects. My work focused on the sister group to the holometabolous insects, the Hemipteroid Assemblage. I participated in the genome annotation of a hemipteras insect, Oncopeltus fasciatus. I annotated nuclear receptor super family, Hox and PRGs in Oncopeltus. I further studied the expression and function of four PRGs in Oncopeltus. Using in situ hybridization and RNAi, I found that, Of-ftz and Of-hairy do not have segmentation function, while Of-ftz-f1 has function in oogenesis and segmentation. Of-runt was found to induce cell death in oocytes, but its function in segmentation needs further analysis. Using the knowledge and expertise I gained from Oncopeltus, I successfully set up in situ hybridization, antibody staining and parental RNAi in an invasive hemipteran insect pest, the Brown Marmorated Stink Bug (BMSB) Halyomorpha halys. These studies show that the expression and function of PRGs varies extensively in diverse insects, despite the overall conservation of a segmented body plan.Item Rapid transcriptome sequencing of an invasive pest, the brown marmorated stink bug Halyomorpha halys(Springer Nature, 2014-08-29) Ioannidis, Panagiotis; Lu, Yong; Kumar, Nikhil; Creasy, Todd; Daugherty, Sean; Chibucos, Marcus C; Orvis, Joshua; Shetty, Amol; Ott, Sandra; Flowers, Melissa; Sengamalay, Naomi; Tallon, Luke J; Pick, Leslie; Dunning Hotopp, Julie CHalyomorpha halys (Stål) (Insecta:Hemiptera;Pentatomidae), commonly known as the Brown Marmorated Stink Bug (BMSB), is an invasive pest of the mid-Atlantic region of the United States, causing economically important damage to a wide range of crops. Native to Asia, BMSB was first observed in Allentown, PA, USA, in 1996, and this pest is now well-established throughout the US mid-Atlantic region and beyond. In addition to the serious threat BMSB poses to agriculture, BMSB has become a nuisance to homeowners, invading home gardens and congregating in large numbers in human-made structures, including homes, to overwinter. Despite its significance as an agricultural pest with limited control options, only 100 bp of BMSB sequence data was available in public databases when this project began. Transcriptome sequencing was undertaken to provide a molecular resource to the research community to inform the development of pest control strategies and to provide molecular data for population genetics studies of BMSB. Using normalized, strand-specific libraries, we sequenced pools of all BMSB life stages on the Illumina HiSeq. Trinity was used to assemble 200,000 putative transcripts in >100,000 components. A novel bioinformatic method that analyzed the strand-specificity of the data reduced this to 53,071 putative transcripts from 18,573 components. By integrating multiple other data types, we narrowed this further to 13,211 representative transcripts. Bacterial endosymbiont genes were identified in this dataset, some of which have a copy number consistent with being lateral gene transfers between endosymbiont genomes and Hemiptera, including ankyrin-repeat related proteins, lysozyme, and mannanase. Such genes and endosymbionts may provide novel targets for BMSB-specific biocontrol. This study demonstrates the utility of strand-specific sequencing in generating shotgun transcriptomes and that rapid sequencing shotgun transcriptomes is possible without the need for extensive inbreeding to generate homozygous lines. Such sequencing can provide a rapid response to pest invasions similar to that already described for disease epidemiology.