Gilsang Jeong

Drosophila DJ-1 decreases neural sensitivity to stress by negatively regulating Daxx-like protein through dFOXO.

DJ-1, a Parkinsons disease (PD)–associated gene, has been shown to protect against oxidative stress in Drosophila. However, the molecular mechanism underlying oxidative stress-induced phenotypes, including apoptosis, locomotive defects, and lethality, in DJ-1-deficient flies is not fully understood. Here we showed that Daxx-like protein (DLP), a Drosophila homologue of the mammalian Death domain-associated protein (Daxx), was upregulated under oxidative stress conditions in the loss-of-function mutants of Drosophila DJ-1β, a Drosophila homologue of DJ-1. DLP overexpression induced apoptosis via the c-Jun N-terminal kinase (JNK)/Drosophila forkhead box subgroup O (dFOXO) pathway, whereas loss of DLP increased resistance to oxidative stress and UV irradiation. Moreover, the oxidative stress-induced phenotypes of DJ-1β mutants were dramatically rescued by DLP deficiency, suggesting that enhanced expression of DLP contributes to the DJ-1β mutant phenotypes. Interestingly, we found that dFOXO was required for the increase in DLP expression in DJ-1β mutants and that dFOXO activity was increased in the heads of DJ-1β mutants. In addition, subcellular localization of DLP appeared to be influenced by DJ-1 expression so that cytosolic DLP was increased in DJ-1β mutants. Similarly, in mammalian cells, Daxx translocation from the nucleus to the cytosol was suppressed by overexpressed DJ-1β under oxidative stress conditions; and, furthermore, targeted expression of DJ-1β to mitochondria efficiently inhibited the Daxx translocation. Taken together, our findings demonstrate that DJ-1β protects flies against oxidative stress- and UV-induced apoptosis by regulating the subcellular localization and gene expression of DLP, thus implying that Daxx-induced apoptosis is involved in the pathogenesis of DJ-1-associated PD.

Dietary hempseed meal intake increases body growth and shortens the larval stage via the upregulation of cell growth and sterol levels in Drosophila melanogaster

Hempseed, a rich source of polyunsaturated fatty acids (PUFAs) and phytosterols, has been recognized as a potential therapeutic food used for cardioprotection, preventing platelet aggregation, and improving atopic dermatitis. Although several studies have revealed the physiological benefits of hempseed on a variety of animals, the effects of dietary hempseed intake on animal development are currently unknown. In this study, we evaluated the developmental effects of the addition of hempseed meal (HSM) to the diet of Drosophila. Interestingly, dietary HSM intake was shown to increase the body size of flies by increasing cell numbers, and also truncated the larval period without affecting survival rate or longevity. The oviposition of female flies was also increased by dietary HSM supplementation. Interestingly, the levels of sterols, which are precursors of ecdysone, a molting hormone, were found to be elevated in the larvae fed on HSM. Additionally, the hexane extracts of hempseed mimicked the effects of HSM on growth, developmental timing, and reproduction. Moreover, among the major nonpolar components of HSM, feeding on cholesterol but not PUFA mix or campesterol accelerated pupariation and increased body size. These results indicate that the dietary intake of HSM accelerates both body growth and developmental rates in Drosophila via the stimulation of cell growth and ecdysone synthesis. Additionally, nonpolar components of hempseed, such as cholesterol, might be responsible for the effects of HSM on development and reproduction.

Incidence of Wolbachia and Cardinium endosymbionts in the Osmia community in Korea.

Sex ratio distorting endosymbionts induce reproductive anomalies in their arthropod hosts. They have recently been paid much attention as firstly texts of evolution of host-symbiont relationships and secondly potential biological control agents to control arthropod pests. Among such organisms, Wolbachia and Cardinium bacteria are well characterized. This study aims at probing such bacteria in the Osmia community to evaluate their potential utilization to control arthropod pests. Among 17 PCR tested species, Osmia cornifrons and a parasitic fly are infected with Wolbachia and a mite species is infected with Cardinium. Phylogenetic tree analyses suggest that horizontal transfer of the bacteria occurred between phylogenetically distant hosts.

dXNP/DATRX increases apoptosis via the JNK and dFOXO pathway in Drosophila neurons.

Mutation of the XNP/ATRX gene, which encodes an SNF2 family ATPase/helicase protein, leads to ATR-X syndrome and several other X-linked mental retardation syndromes. Although XNP/ATRX is a chromatin remodeler, the molecular mechanism by which mental retardation occurs in patients with ATR-X has yet to be determined. To better understand the role of XNP/ATRX in neuronal development, we expressed Drosophila XNP (dXNP/DATRX) ectopically in Drosophila neurons. Neuronal expression of dXNP/DATRX resulted in various developmental defects and induced strong apoptosis. These defects and apoptosis were suppressed by Drosophila inhibitor of apoptosis protein 1. Expression of dXNP/DATRX also increased JNK activity and the levels of reaper and hid transcripts, which are pro-apoptotic factors that activate caspase. Furthermore, dXNP/DATRX-induced rough eye phenotype and apoptosis were suppressed by dFOXO deficiency. These results suggest that dXNP/DATRX is involved in caspase-dependent apoptosis in Drosophila neurons via regulation of the JNK and dFOXO pathway.

Structure of ribosomal RNA gene and phytogeny ofNosema isolates in Korea

The ribosomal RNA (rRNA) gene region of the fourNosema sp. isolates (C01, C02, C03 and C04) fromPieris rapae in Korea has been examined. Complete DNA sequence data (3779 bp) of The rRNA gene ofNosema sp. C01 are presented for the small subunit gene (SSU rRNA: 1236 bp), the internal transcribed spacer (ITS: 37 bp), and the large subunit gene (LSU rRNA 2506 bp). The secondary structures ofNosema sp. COI SSU and LSU rRNA genes are constructed and described. The SSU rRNA showed a hypervariable V4 region identified four additional stems including a pseudoknot. Phylogenetic analysis based on the SSU rRNA suggests that the four isolates belong to the ‘true’Nosema group. In contrast to theNosema/Vairimorpha clade, the members of the group are highly divergent.

Survey on insect fauna and role of insect gardens for ecotourism.

This study was conducted to investigate insect fauna in the four insect garden sites of Suwon, Yeongyang, Buyeo and Yecheon from 2005 to 2007. Seasonal population size of insects was largest from June to August in all the four sites. In the four sites, Coleopteran insects were dominant followed by Hemiptera and Orthoptera. Unique education/learning programs are successfully run at the insect gardens based on the three geographic types (i.e. urban, mountainous and rural). These activities will help preserve insect biodiversity in the area and visitors better understand life forms such as insects found in the areas.