3,434 research outputs found

    A Survey for Potential Biocontrol Agents of Bactrocera cucurbitae (Diptera: Tephritidae) in Thailand

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    Scientific note.Limited investigations on parasitoids of the melon fly, Bactrocera cucurbitae (Coquillett), infesting five species of Cucurbitaceae and seven species of Solanaceae were conducted in Thailand to determine natural occurrence of biological control agents. Fruit samples were collected during January-February 1996, and tephritid puparia were imported into the State of Hawaii Quarantine Facility for fly and parasitoid emergence. Cucumis sativus L., Luffa acutangula (L.), and Momordica charantia L. were commonly infested by B. cucurbitae. Bactrocera tau (Walker) was dominant only in L. acutangula. Infestation of ripe, cultivated fruit of M. charantia was 72.3 B. cucurbitae/kg fruit and parasitoids were pre-dominantly Psyttalia fletcheri (Silvestri) (Hymenoptera: Braconidae), with parasitization rates up to 12.4%. Bactrocera cucurbitae infesting M. charantia in northern Thailand yielded an unidentified Aceratoneuromyia species, (Hymenoptera: Eulophidae). Unlike other eulophids that attack B. cucurbitae, which require the presence of P. fletcheri in the same puparium to suppress host immunity, this parasitoid was able to develop alone. Average fecundity was 135 offspring/ female and mean parasitoids /host puparium was 21.1. It was also developed in the laboratory on the Mediterranean fruit fly, Ceratitis capitata (Wiedemann), with an average life span of 23 d in both host species. Six species of solanaceous fruit were mainly infested by Bactrocera latifrons (Hendel), with infestation rates ranging from 4 to 17 flies/kg fruit. Psyttalia fletcheri and unidentified opiine, Bitomus species, eclosed from B. latifrons infested bird chili, Capsicum frustescens L. Only Lycopersicon esculentum Mill. produced B. cucurbitae, lightly parasitized by P. fletcheri

    The Genera and Species of Comatulidae (Comatulida: Crinoidea): Taxonomic Revisions and a Molecular and Morphological Guide

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    We provide a guide for identification of Comatulidae, a family of crinoid echinoderms, incorporating morphological and molecular evidence. A non-dichotomous key for all genera is included, as well as photographs of species most likely to be encountered in the tropical western Pacific Ocean. Based on sequencing of cytochrome oxidase subunit I (COI), and other genes when necessary, we identified four cases where taxonomic revision was needed. We synonymized Comaster nobilis under Comaster schlegelii, and Clarkcomanthus exilis under Clarkcomanthus comanthipinnus, and re-described Clarkcomanthus albinotus. We also showed the variation of COI sequences within and among species, which varies from lineage to lineage. In some cases, specimens with obvious morphological disparity possessed very little intraspecific molecular diversity (\u3c1%). In others, specimens with nearly identical external appearances exhibited quite divergent COI sequences (up to 6%). These results, combined with the non-dichotomous key herein, offer guidelines for identification and discussion of existing and new species of Comatulidae

    Genetic Ablation of Nrf2/Antioxidant Response Pathway in Alexander Disease Mice Reduces Hippocampal Gliosis but Does Not Impact Survival

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    In Alexander disease (AxD) the presence of mutant glial fibrillary acidic protein (GFAP), the major intermediate filament of astrocytes, triggers protein aggregation, with marked induction of a stress response mediated by the transcription factor, Nrf2. To clarify the role of Nrf2 in AxD, we have crossed Gfap mutant and transgenic mouse models into an Nrf2 null background. Deletion of Nrf2 eliminates the phase II stress response normally present in mouse models of AxD, but causes no change in body weight or lifespan, even in a severe lethal model. AxD astrocytes without Nrf2 retain features of reactivity, such as expression of the endothelin-B receptor, but have lower Gfap levels, a decrease in p62 protein and reduced iron accumulation, particularly in hippocampus. Microglial activation, indicated by Iba1 expression, is also diminished. Although the Nrf2 response is generally considered beneficial, these results show that in the context of AxD, loss of the antioxidant pathway has no obvious negative effects, while actually decreasing Gfap accumulation and pathology. Given the attention Nrf2 is receiving as a potential therapeutic target in AxD and other neurodegenerative diseases, it will be interesting to see whether induction of Nrf2, beyond the endogenous response, is beneficial or not in these same models

    Divergent properties of prolamins in wheat and maize

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    Cereal grains are an important nutritional source of amino acids for humans and livestock worldwide. Wheat, barley, and oats belong to a different subfamily of the grasses than rice and in addition to maize, millets, sugarcane, and sorghum. All their seeds, however, are largely devoid of free amino acids because they are stored during dormancy in specialized storage proteins. Prolamins, the major class of storage proteins in cereals with preponderance of proline and glutamine, are synthesized at the endoplasmic reticulum during seed development and deposited into subcellular structures of the immature endosperm, the protein bodies. Prolamins have diverged during the evolution of the grass family in their structure and their properties. Here, we used the expression of wheat glutenin-Dx5 in maize to examine its interaction with maize prolamins during endosperm development. Ectopic expression of Dx5 alters protein body morphology in a way that resembles non-vitreous kernel phenotypes, although Dx5 alone does not cause an opaque phenotype. However, if we lower the amount of γ-zeins in Dx5 maize through RNAi, a non-vitreous phenotype emerges and the deformation on the surface of protein bodies is enhanced, indicating that Dx5 requires γ-zeins for its proper subcellular organization in maize

    Flight Investigation of the Cooling Characteristics of a Two-row Radial Engine Installation III : Engine Temperature Distribution

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    The temperature distribution of a two-row radial engine in a twin-engine airplane has been investigated in a series of flight tests. The test engine was operated over a wide range of conditions at density altitudes of 5000 and 20,000 feet; quantitative results are presented showing the effects of flight and engine variables upon average engine temperature and over-all temperature spread. Discussions of the effect of the variables on the shape of the temperature patterns and on the temperature distribution of individual cylinders are also included. The results indicate that, for the tests conducted, the temperature distribution patterns were chiefly determined by the fuel-air ratio and cooling-air distributions. It was possible to calculate individual cylinder temperature, on the assumption of equal power distribution among cylinders, to within an average of plus or minus 14 degrees F. of the actual temperature. A considerable change occurred in either the spread or the thrust axis, the average engine fuel-air ratio, the engine speed, the power, or the blower ratio. Smaller effects on the temperature pattern were noticed with a change in cowl-flap opening and altitude. In most of the tests, a change in conditions affected the temperature of the barrels less than that of the heads. The variation of flight and engine variables had a negligible effect on the temperature distributions of the individual cylinders. (author

    Light and Vision in the Deep-Sea Benthos: I. Bioluminescence at 500-1000 m Depth in the Bahamian Islands

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    Bioluminescence is common and well studied in mesopelagic species. However, the extent of bioluminescence in benthic sites of similar depths is far less studied, although the relatively large eyes of benthic fish, crustaceans and cephalopods at bathyal depths suggest the presence of significant biogenic light. Using the Johnson-Sea-Link submersible, we collected numerous species of cnidarians, echinoderms, crustaceans, cephalopods and sponges, as well as one annelid from three sites in the northern Bahamas (500–1000 m depth). Using mechanical and chemical stimulation, we tested the collected species for light emission, and photographed and measured the spectra of the emitted light. In addition, in situ intensified video and still photos were taken of different benthic habitats. Surprisingly, bioluminescence in benthic animals at these sites was far less common than in mesopelagic animals from similar depths, with less than 20% of the collected species emitting light. Bioluminescent taxa comprised two species of anemone (Actinaria), a new genus and species of flabellate Parazoanthidae (formerly Gerardia sp.) (Zoanthidea), three sea pens (Pennatulacea), three bamboo corals (Alcyonacea), the chrysogorgiid coral Chrysogorgia desbonni (Alcyonacea), the caridean shrimp Parapandalus sp. and Heterocarpus ensifer (Decapoda), two holothuroids (Elasipodida and Aspidochirota) and the ophiuroid Ophiochiton ternispinus (Ophiurida). Except for the ophiuroid and the two shrimp, which emitted blue light (peak wavelengths 470 and 455 nm), all the species produced greener light than that measured in most mesopelagic taxa, with the emissions of the pennatulaceans being strongly shifted towards longer wavelengths. In situ observations suggested that bioluminescence associated with these sites was due primarily to light emitted by bioluminescent planktonic species as they struck filter feeders that extended into the water column

    Vision and Bioluminescence in the Deep-Sea Benthos

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    During a NOAA-OER funded research cruise, novel collecting techniques were used to collect live, deep-sea benthic animals for studies of bioluminescence and vision. True color images and emission spectra of bioluminescence were obtained from a number of species, including the spiral octocoral Iridogorgia sp., the sea fan Chrysogorgia sp., the sea pen Umbellula sp., and the caridean shrimp Heterocarpusoryx. Electrophysiological studies were conducted on 3 species of decapod crustaceans collected with methods that limited light damage to their photoreceptors. The caridean shrimp, Bathypalaemonella, collected from 1920m, was always found in association with the bioluminescent spiral octocoral Iridogorgia. While moribund at the surface, enough data were obtained from one specimen to show different wave forms in response to short and long wavelength light, indicative of two different classes of photoreceptor cells. The chirostylid crab, Uroptychusnitidus, found in association with the bioluminescent sea fan, Chrysogorgia sp., also appears to possess two visual pigments, and if further analysis of data supports this preliminary observation, will be the 4th species of deep-sea, non-bioluminescent crustaceans possessing two visual pigments found in association with bioluminescent cnidarians. These four species also share another characteristic–the presence of one or two very long claws, which the crab species are known to use to pick items (possibly plankton stuck in the mucus) off their cnidarian hosts. These data support the previously presented hypothesis (Frank et al. 2012), that these crustaceans may be utilizing their dual visual pigment systems to distinguish between prey and host, based on spectral differences between pelagic and benthic bioluminescence.

    Rotation Measure Synthesis of Galactic Polarized Emission with the DRAO 26-m Telescope

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    Radio polarimetry at decimetre wavelengths is the principal source of information on the Galactic magnetic field. The diffuse polarized emission is strongly influenced by Faraday rotation in the magneto-ionic medium and rotation measure is the prime quantity of interest, implying that all Stokes parameters must be measured over wide frequency bands with many frequency channels. The DRAO 26-m Telescope has been equipped with a wideband feed, a polarization transducer to deliver both hands of circular polarization, and a receiver, all operating from 1277 to 1762 MHz. Half-power beamwidth is between 40 and 30 arcminutes. A digital FPGA spectrometer, based on commercially available components, produces all Stokes parameters in 2048 frequency channels over a 485-MHz bandwidth. Signals are digitized to 8 bits and a Fast Fourier Transform is applied to each data stream. Stokes parameters are then generated in each frequency channel. This instrument is in use at DRAO for a Northern sky polarization survey. Observations consist of scans up and down the Meridian at a drive rate of 0.9 degree per minute to give complete coverage of the sky between declinations -30 degree and 90 degree. This paper presents a complete description of the receiver and data acquisition system. Only a small fraction of the frequency band of operation is allocated for radio astronomy, and about 20 percent of the data are lost to interference. The first 8 percent of data from the survey are used for a proof-of-concept study, which has led to the first application of Rotation Measure Synthesis to the diffuse Galactic emission obtained with a single-antenna telescope. We find rotation measure values for the diffuse emission as high as approximately 100 rad per square metre, much higher than recorded in earlier work.Comment: Accepted for publication in The Astronomical Journa
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