Publications by authors named "Hyuckjin Nam"

Article Synopsis
  • Pyruvate plays a crucial role in carbohydrate metabolism, influencing whether cells focus on energy production or building biomass, with effects observed in both proliferating and non-dividing cells like the fat body.
  • Research found that increasing mitochondrial pyruvate import inhibited cell growth in fat body cells and liver cells, linked to a rise in the NADH/NAD ratio which shifted metabolism away from glycolysis toward gluconeogenesis.
  • Despite active growth-signaling pathways like mTORC1 and Myc, the changes in pyruvate metabolism led to decreased amino acid and protein synthesis, ultimately suppressing cell growth in specialized, long-term cells.
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Nutrient digestion, absorption, and export must be coordinated in the gut to meet the nutritional needs of the organism. We used the Drosophila intestine to characterize the mechanisms that coordinate the fate of dietary lipids. We identified enterocytes specialized in absorbing and exporting lipids to peripheral organs.

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Hybrid male sterility is one of the fastest evolving intrinsic reproductive barriers between recently isolated populations. A leading explanation for the evolution of hybrid male sterility involves genomic conflicts with meiotic drivers in the male germline. There are, however, few examples directly linking meiotic drive to hybrid sterility.

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Recent advances in numerous biological applications have increased the accuracy of monitoring the level of biologically significant analytes in the human body to manage personal nutrition and physiological conditions. However, despite promising reports about costly wearable devices with high sensing performance, there has been a growing demand for inexpensive sensors that can quickly detect biological molecules. Herein, we present highly sensitive biosensors based on organic electrochemical transistors (OECTs), which are types of organic semiconductor-based sensors that operate consistently at low operating voltages in aqueous solutions.

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Hybrid male sterility is one of the fastest evolving intrinsic reproductive barriers between recently isolated populations. A leading explanation for the evolution of hybrid male sterility involves genomic conflicts with meiotic drivers in the male germline. There are, however, few examples directly linking meiotic drive to hybrid sterility.

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Among various conductive polymers, the poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) film has been studied as a promising material for use as a transparent electrode and a hole-injecting layer in organic optoelectronic devices. Due to the increasing demand for the low-cost fabrication of organic light-emitting diodes (OLEDs), PEDOT:PSS has been employed as the top electrode by using the coating or lamination method. Herein, a facile method is reported for the fabrication of highly efficient polymer light-emitting diodes (PLEDs) based on a laminated transparent electrode (LTE) consisting of successive PEDOT:PSS and silver-nanowire (AgNW) layers.

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Pulses of the steroid hormone ecdysone act through transcriptional cascades to direct the major developmental transitions during the Drosophila life cycle. These include the prepupal ecdysone pulse, which occurs 10 ​hours after pupariation and triggers the onset of adult morphogenesis and larval tissue destruction. E93 encodes a transcription factor that is specifically induced by the prepupal pulse of ecdysone, supporting a model proposed by earlier work that it specifies the onset of adult development.

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Successful reproduction is dependent on the transfer of male seminal proteins to females upon mating. These proteins arise from secretory tissues in the male reproductive tract, including the prostate and seminal vesicles in mammals and the accessory gland in insects. Although detailed functional studies have provided important insights into the mechanisms by which accessory gland proteins support reproduction, much less is known about the molecular mechanisms that regulate their expression within this tissue.

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Background: Lipid levels are maintained by balancing lipid uptake, synthesis, and mobilization. Although many studies have focused on the control of lipid synthesis and mobilization, less is known about the regulation of lipid digestion and uptake.

Results: Here we show that the Drosophila E78A nuclear receptor plays a central role in intestinal lipid homeostasis through regulation of the CG17192 digestive lipase.

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Article Synopsis
  • Animals adjust their metabolism throughout their life cycle, and in Drosophila, the dHNF4 nuclear receptor initiates a crucial switch in lipid metabolism at the beginning of adulthood.
  • This switch converts lipid stores into long chain fatty acids and hydrocarbons that help waterproof the insect and maintain fluid balance.
  • The dHNF4 pathway not only promotes longevity and resistance to dehydration but also helps manage issues related to diabetes, highlighting its evolutionary significance.
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Commensalibacter intestini A911(T), a predominant symbiotic bacterium capable of stably colonizing gut epithelia, was isolated from the fruit fly, Drosophila melanogaster. Here we report the draft genome sequence of Commensalibacter intestini A911(T).

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Gluconobacter morbifer G707(T), a minor member of gut microbiota, was isolated from fruit fly (Drosophila melanogaster). Here, the draft genome sequence of Gluconobacter morbifer G707(T) is reported.

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Article Synopsis
  • * Researchers identified a key genetic factor, Hayan, which activates a pathway involving the conversion of pro-phenoloxidase to phenoloxidase, facilitating the wound response.
  • * The activation of this enzyme cascade plays a significant role in triggering protective mechanisms in neuronal tissues, illustrating a connection between wound healing and the nervous system's maintenance of overall health after injury.
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All metazoan guts are in constant contact with diverse food-borne microorganisms. The signaling mechanisms by which the host regulates gut-microbe interactions, however, are not yet clear. Here, we show that phospholipase C-beta (PLCbeta) signaling modulates dual oxidase (DUOX) activity to produce microbicidal reactive oxygen species (ROS) essential for normal host survival.

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Phenoloxidase (PO), a melanin-forming enzyme around the foreign bodies, is an important component of the host defense system in invertebrates. Pro-PO is the enzymatically inactive zymogen form of PO. In the Drosophila genome, three Pro-PO isoforms have been identified to date.

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Article Synopsis
  • Extracellular proteases, including CLIP-domain serine proteases (clip-SPs), are crucial for various physiological functions in hosts, such as digestion, immunity, and tissue degradation.
  • CLIP-SPs, identified by their unique "paper clip" structure, have recently been linked to important biological processes like immunity and development, but their in vivo roles remain understudied due to limited genetic research.
  • Drosophila (fruit flies) have emerged as a beneficial model for studying clip-SPs, with current knowledge on their function summarized and suggestions for future research on their role in Drosophila immunity outlined.
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Article Synopsis
  • The Drosophila Toll receptor is activated by the cleaved cytokine Spatzle (Spz), rather than directly responding to microbes like mammalian Toll-like receptors.
  • Researchers conducted an in vivo RNAi study to silence 75 Drosophila serine protease genes, searching for those that influence the Toll pathway in response to gram-positive bacteria.
  • They identified five new serine proteases that connect recognition proteins to Spz, with four involved in fungal responses and one specifically for gram-positive bacteria, indicating a coordinated signaling pathway.
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The Toll receptor was originally identified as an indispensable molecule for Drosophila embryonic development and subsequently as an essential component of innate immunity from insects to humans. Although in Drosophila the Easter protease processes the pro-Spätzle protein to generate the Toll ligand during development, the identification of the protease responsible for pro-Spätzle processing during the immune response has remained elusive for a decade. Here, we report a protease, called Spätzle-processing enzyme (SPE), required for Toll-dependent antimicrobial response.

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In Drosophila melanogaster, although the NF-kappaB transcription factors play a pivotal role in the inducible expression of innate immune genes, such as antimicrobial peptide genes, the exact regulatory mechanism of the tissue-specific constitutive expression of these genes in barrier epithelia is largely unknown. Here, we show that the Drosophila homeobox gene product Caudal functions as the innate immune transcription modulator that is responsible for the constitutive local expression of antimicrobial peptides cecropin and drosomycin in a tissue-specific manner. These results suggest that certain epithelial tissues have evolved a unique constitutive innate immune strategy by recruiting a developmental "master control" gene.

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