521 research outputs found

    The mutualistic fungus Piriformospora indica colonizes Arabidopsis roots by inducing an endoplasmic reticulum stress-triggered caspase-dependent cell death

    Get PDF
    In Arabidopsis thaliana roots, the mutualistic fungus Piriformospora indica initially colonizes living cells, which die as the colonization proceeds. We aimed to clarify the molecular basis of this colonization-associated cell death. Our cytological analyses revealed endoplasmic reticulum (ER) swelling and vacuolar collapse in invaded cells, indicative of ER stress and cell death during root colonization. Consistent with this, P. indica–colonized plants were hypersensitive to the ER stress inducer tunicamycin. By clear contrast, ER stress sensors bZIP60 and bZIP28 as well as canonical markers for the ER stress response pathway, termed the unfolded protein response (UPR), were suppressed at the same time. Arabidopsis mutants compromised in caspase 1–like activity, mediated by cell death–regulating vacuolar processing enzymes (VPEs), showed reduced colonization and decreased cell death incidence. We propose a previously unreported microbial invasion strategy during which P. indica induces ER stress but inhibits the adaptive UPR. This disturbance results in a VPE/caspase 1–like-mediated cell death, which is required for the establishment of the symbiosis. Our results suggest the presence of an at least partially conserved ER stress–induced caspase-dependent cell death pathway in plants as has been reported for metazoans

    Resource Management in Diffserv On DemAnd (RODA) PHR

    Get PDF
    The purpose of this draft is to present the Resource Management in Diffserv (RMD) On DemAnd (RODA) Per Hop Reservation (PHR) protocol. The RODA PHR protocol is used on a per-hop basis in a Differentiated Services (Diffserv) domain and extends the Diffserv Per Hop Behavior (PHB) with resource provisioning and control

    Lack of evidence for western flower thrips biotypes base don intra and inter-strain variation in gut bacteria

    Get PDF
    Western flower thrips is a polyphagous insect, which during the last 30 years has become a world wide pest. It was found earlier that these thrips are associated with a type of Erwinia species gut bacteria. In this study we examine the variation of bacteria within and between thrips individuals and try to find evidence for biotypes in western flower thrips regarding the type of gut bacteria. The existence of biotypes in this thrips species has been suggested by different authors. For example, thrips populations have been found that differ in resistance against pesticides and in their ability to transmit plant viruses. With biotypes we mean groups of individuals (strains, populations, lines) of a species which differ in one or more traits with other groups of that species. The gut bacteria of thrips are acquired by young thrips larvae via the host plant and have a beneficial effect on thrips development and oviposition. We studied thrips strains from different countries and host plants, and the isofemale lines that were created from them, on bean plant leaves. All thrips lines that we studied contained Erwinia species gut bacteria. Morphological and biochemical characteristics of gut bacteria from the thrips isofemale lines were similar to the Erwinia type strain from the reference, a thrips strain cultured on chrysanthemum in Amsterdam (TAC 93.XII.8). Per isofemale line we studied five thrips individuals and per thrips we studied four bacterial colonies, with RAPD markers. The genetic variation between bacteria isolated from thrips was as large among isofemale lines as within isofemale lines. No evidence for thrips biotypes was found. Bacteria within one thrips individual show a stronger degree of similarity than bacteria from different thrips individuals within a single rearing. This is probably due to a bottleneck caused by the limited number of successful infections of bacteria into the gut of the thrip

    Efektivitas Model dan Ketinggian Perangkap dalam Menangkap Hama Lalat Buah Jantan, Bactrocera Spp

    Full text link
    . Penelitian ini bertujuan mengetahui model dan ketinggian perangkap yang efektif dalam menangkap lalat buah, Bactrocera spp. Penelitian ini dilakukan di kebun petani di Kenagarian Kacang pada pertanaman polikultur dan Alahan Panjang pada pertanaman monokultur, Solok mulai Maret 2003-Desember 2004. Model alat perangkap yang digunakan dalam penelitian ini yaitu perangkap bekas botol air mineral, modifikasi gipsy moth, modifikasi perangkap steiner, perangkap delta, dan perangkap McPhail. Masing-masing perangkap diberi umpan dengan 0,5 ml metil eugenol atau cue lure yang diteteskan pada sepotong kapas dan digantungkan di dalam perangkap. Untuk mengetahui ketinggian perangkap yang efektif untuk menangkap lalat buah, penelitian dilakukan dengan memasang perangkap dari botol air mineral pada ketinggian 0,5, 1, 1,5, 2, dan 2,5 m dari permukaan tanah. Hasil penelitian menunjukkan bahwa jumlah lalat buah yang tertangkap per perangkap/hari pada masing-masing jenis perangkap yang digunakan berbeda nyata. Lalat buah yang paling banyak tertangkap per perangkap/hari adalah pada perangkap McPhail yaitu 52 ekor dan yang paling sedikit diperoleh pada perangkap gipsy moth yaitu 6 ekor/perangkap/hari. Ketinggian perangkap terlihat berbeda nyata, di mana lalat buah yang paling banyak tertangkap adalah pada perangkap dengan ketinggian 1,5 m dari permukaan tanah. Penggabungan antara model perangkap dengan atraktan sintetis, seperti metil eugenol atau cue lure meningkatkan kemampuan tidak hanya sebagai perangkap lalat buah yang potentsial tetapi juga sebagai alat monitoring hama lalat buah

    Distribusi Spesies Lalat Buah di Sumatera Barat dan Riau

    Full text link
    . Penelitian ini bertujuan mengetahui distribusi dan diversitas spesies lalat buah di Sumatera Barat dan Pulau Kundur Kabupaten Karimun, Riau. Penelitian dilakukan dengan metode survei mulai bulan Juni 2003 – Desember 2004. Lalat buah ditangkap menggunakan perangkap yang terbuat dari botol bekas air mineral yang di dalamnya digantungkan kapas yang telah dibasahi dengan metil eugenol dan cue lure. Lalat buah hasil tangkapan dibawa ke Laboratorium Proteksi Balai Penelitian Tanaman Buah Tropika Solok untuk diidentifikasi menggunakan kunci identifikasi elektronik Cabikey. Hasil penelitian menunjukkan bahwa dari semua lokasi penelitian diperoleh 45 spesies lalat buah (2 spesies belum teridentifikasi). Tiga spesies lalat buah ditemukan di semua lokasi penelitian, yaitu B. albistrigata, B. carambolae, dan B. papayae. Keragaman spesies lalat buah paling tinggi ditemukan di Kabupaten Solok, Sumatera Barat dan Pulau Kundur, berturut-turut ditemukan 30 spesies dan 25 spesies lalat buah. Hasil penelitian ini bermanfaat sebagai informasi terutama bagi karantina sebagai dasar untuk memperketat aturan mengenai keluar masuknya buah-buahan dari dan ke suatu daerah sehingga spesies-spesies yang ada di daerah tertentu terutama daerah yang mempunyai diversitas spesies tinggi tidak masuk ke daerah lain

    Cluster-based network proximities for arbitrary nodal subsets

    Get PDF
    The concept of a cluster or community in a network context has been of considerable interest in a variety of settings in recent years. In this paper, employing random walks and geodesic distance, we introduce a unified measure of cluster-based proximity between nodes, relative to a given subset of interest. The inherent simplicity and informativeness of the approach could make it of value to researchers in a variety of scientific fields. Applicability is demonstrated via application to clustering for a number of existent data sets (including multipartite networks). We view community detection (i.e. when the full set of network nodes is considered) as simply the limiting instance of clustering (for arbitrary subsets). This perspective should add to the dialogue on what constitutes a cluster or community within a network. In regards to health-relevant attributes in social networks, identification of clusters of individuals with similar attributes can support targeting of collective interventions. The method performs well in comparisons with other approaches, based on comparative measures such as NMI and ARI

    Rab3D is critical for secretory granule maturation in PC12 cells.

    Get PDF
    Neuropeptide- and hormone-containing secretory granules (SGs) are synthesized at the trans-Golgi network (TGN) as immature secretory granules (ISGs) and complete their maturation in the F-actin-rich cell cortex. This maturation process is characterized by acidification-dependent processing of cargo proteins, condensation of the SG matrix and removal of membrane and proteins not destined to mature secretory granules (MSGs). Here we addressed a potential role of Rab3 isoforms in these maturation steps by expressing their nucleotide-binding deficient mutants in PC12 cells. Our data show that the presence of Rab3D(N135I) decreases the restriction of maturing SGs to the F-actin-rich cell cortex, blocks the removal of the endoprotease furin from SGs and impedes the processing of the luminal SG protein secretogranin II. This strongly suggests that Rab3D is implicated in the subcellular localization and maturation of ISGs

    Экспериментальное исследование синхронного генератора периодических импульсов

    Get PDF
    Приводятся результаты экспериментального исследования влияния величины нагрузки синхронного генератора периодических импульсов с обычной геометрией зубцовой зоны на форму импульсов тока. Рассматривается возможность регулировки параметров импульсов
    corecore