Search results for "Insect Science"
showing 10 items of 1011 documents
Characterization of cell lines carrying self-replicating hepatitis C virus RNAs.
2001
ABSTRACT Subgenomic selectable RNAs of the hepatitis C virus (HCV) have recently been shown to self-replicate to high levels in the human hepatoma cell line Huh-7 (V. Lohmann, F. Körner, J. O. Koch, U. Herian, L. Theilmann, and R. Bartenschlager, Science 285:110–113, 1999). Taking advantage of this cell culture system that allows analyses of the interplay between HCV replication and the host cell, in this study we characterized two replicon-harboring cell lines that have been cultivated for more than 1 year. During this time, we observed no signs of cytopathogenicity such as reduction of growth rates or ultrastructural changes. High levels of HCV RNAs were preserved in cells passaged under…
Sequences in the 5′ Nontranslated Region of Hepatitis C Virus Required for RNA Replication
2001
ABSTRACT Sequences in the 5′ and 3′ termini of plus-strand RNA viruses harbor cis -acting elements important for efficient translation and replication. In case of the hepatitis C virus (HCV), a plus-strand RNA virus of the family Flaviviridae , a 341-nucleotide-long nontranslated region (NTR) is located at the 5′ end of the genome. This sequence contains an internal ribosome entry site (IRES) that is located downstream of an about 40-nucleotide-long sequence of unknown function. By using our recently developed HCV replicon system, we mapped and characterized the sequences in the 5′ NTR required for RNA replication. We show that deletions introduced into the 5′ terminal 40 nucleotides abolis…
Mutations in hepatitis C virus RNAs conferring cell culture adaptation.
2001
ABSTRACT As an initial approach to studying the molecular replication mechanisms of hepatitis C virus (HCV), a major causative agent of acute and chronic liver disease, we have recently developed selectable self-replicating RNAs. These replicons lacked the region encoding the structural proteins and instead carried the gene encoding the neomycin phosphotransferase. Although the replication levels of these RNAs within selected cells were high, the number of G418-resistant colonies was reproducibly low. In a search for the reason, we performed a detailed analysis of replicating HCV RNAs and identified several adaptive mutations enhancing the efficiency of colony formation by several orders of…
Hyperparasitism and seasonal patterns of parasitism as potential causes of low top-down control in Euproctis chrysorrhoea (Lymantriidae)
2012
Pest suppression is an important ecosystem service provided by biodiversity, though antagonistic interactions may jeopardize its impact on pest suppression. Hyperparasitoids may release herbivore populations from natural enemy pressure and lead to outbreaks directly due to parasitism as well as indirect through behavioural interference. In a previous study we reported that in native populations of Euproctis chrysorrhoea L. (Lymantriidae) primary parasitism was very low and outbreaks were more likely in coastal habitats than inland. Here we hypothesise that hyperparasitoids are the underlying cause of such patterns by reporting data on direct hyperparasitism rates as well as seasonal pattern…
Contrasting reproductive traits of competing parasitoids facilitate coexistence on a shared host pest in a biological control perspective
2022
BACKGROUND: Interspecific competition in insect parasitoids is an important ecological phenomenon that has relevant implications for biological pest control. To date, interspecific intrinsic (=larval) competition has been intensively studied, while investigations on extrinsic (=adult) competition have often lagged behind. In this study we examined the role played by parasitoid reproductive traits and host clutch size on the outcome of extrinsic competition between Trissolcus basalis (Wollaston) and Ooencyrtus telenomicida (Vassiliev), two egg parasitoids of the pest Nezara viridula (L). Laboratory experiments were conducted by allowing both parasitoid species to exploit an egg mass made of …
Two new African and Madagascan species of the genus Holochlora (Orthoptera: Tettigoniidae, Phaneropterinae)
2017
Two new species, Holochlora mauritiana and H. ingrischi from the island of Mauritius and Zimbabwe, respectively, are described. Along with a third species, H. biloba Stål, 1874 from Madagascar, they are the sole African representatives of the mostly Oriental genus Holochlora Stål, 1873, including ca. 60 taxa distributed from India to China. Preliminary hypotheses on biogeographical and evolutionary origin of Afro-Madagascan Holochlora species are shortly discussed.
Feeding habits, post-embryonic and adult survival, mating, virility and fecundity of the predacious miteAmblyseius swirskii [Acarina: Phytoseiidae] o…
1977
The nutritional value forAmblyseius swirskiiAthias-Henriot, of eggs or crawlers ofCoccus hesperidum L.,Saissetia oleae (Olivier),S. coffeae (Walker),Pseudococcus citriculusGreen, andP. longispinusTarg.-Tozz, even with the addition of honeydew, was low; only a few young reached adulthood and the oviposition rate was negligible. However, addition of honeydew toTetranychus cinnabarinusBoisd. enhanced the oviposition rate ofAmblyseius swirskii. Honeydew was a favourite food forA. swirskii, whereas the eggs and crawlers tested were not eagerly attacked and consumed. Females and males fed honeydew ofSaissetia oleae mated readily and the females were inseminated, but fecundity was negligible.
A heterocyclic oxime from a fungus with anti-juvenile hormone activity
1998
Two fractions obtained after chromatography of dichloromethane extract of Penicillium brevicompactum culture medium showed anti-juvenile hormone activity. One was active when assayed in vivo against Oncopeltus fasciatus third-instar nymphs, whereas the other showed a strong in vitro inhibition of JH III biosynthesis on Locusta migratoria corpora allata. A subfraction of the latter, constituting 97% of this fraction, is a main component that possessed the juvenile hormone biosynthesis inhibitory activity. Chemical characterization of this compound shows a sesquiterpene-like structure, molecular mass of 278.16185 daltons, corresponding to an empirical formula of C15H22N2O3 named brevioxime. E…
Raman Spectroscopic Signatures of Echovirus 1 Uncoating
2014
ABSTRACT In recent decades, Raman spectroscopy has entered the biological and medical fields. It enables nondestructive analysis of structural details at the molecular level and has been used to study viruses and their constituents. Here, we used Raman spectroscopy to study echovirus 1 (EV1), a small, nonenveloped human pathogen, in two different uncoating states induced by heat treatments. Raman signals of capsid proteins and RNA genome were observed from the intact virus, the uncoating intermediate, and disrupted virions. Transmission electron microscopy data revealed general structural changes between the studied particles. Compared to spectral characteristics of proteins in the intact v…
Experiments on the ectoparasitic deer ked that often attacks humans; preferences for body parts, colour and temperature.
2009
AbstractThe deer ked (Lipoptena cervi) can fail in its host search. Host search fails when an individual deer ked irreversibly accepts a host unsuitable for its reproduction (e.g. a human) and drops its wings. In northern Europe, the main host of the deer ked is the moose (Alces alces). The deer ked is increasingly causing serious problems for humans (for example, causing deer ked dermatitis) and is considered a threat for the recreational use of forests. The adult deer ked flies in early and mid-autumn to search for a host. Our aims were: (i) to study whether there are ways to avoid deer ked attacks by wearing particular clothing, and (ii) to evaluate deer ked host choice. Using human targ…