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Geng K, Zhang Y, Zhao X, Zhang W, Guo X, He L, Liu K, Yang H, Hong H, Peng J, Peng R. Fluorescent Nanoparticle-RNAi-Mediated Silencing of Sterol Carrier Protein-2 Gene Expression Suppresses the Growth, Development, and Reproduction of Helicoverpa armigera. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:nano13020245. [PMID: 36677998 PMCID: PMC9866532 DOI: 10.3390/nano13020245] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Revised: 12/27/2022] [Accepted: 01/03/2023] [Indexed: 05/23/2023]
Abstract
Helicoverpa armigera is a polyphagous destructive lepidopteran pest with strong Bacillus thuringiensis (Bt) resistance. Cholesterol, a vital component for insect growth, can only be obtained from food, and its transfer and metabolism are regulated by sterol carrier protein-2 (SCP-2). This study examined whether H. armigera SCP-2 (HaSCP-2) gene expression, involved in cholesterol absorption, can be silenced by nanocarrier fluorescent nanoparticle-RNA interference (FNP-RNAi) by larval feeding and whether the silencing affected H. armigera development. Fluorescence microscopy showed that nanoparticle-siRNA was distributed in Ha cells and the larval midgut. FNP-HaSCP-2 siRNA suppressed HaSCP-2 expression by 52.5% in H.armigera Ha cells. FNP can effectively help deliver siRNA into cells, protect siRNA, and is not affected by serum. FNP-siRNA in vivo biological assays showed that HaSCP-2 transcript levels were inhibited by 70.19%, 68.16%, and 67.66% in 3rd, 4th, and 5th instar larvae, leading to a decrease in the cholesterol level in the larval and prepupal fatbodies. The pupation rate and adult emergence were reduced to 26.0% and 56.52%, respectively. This study demonstrated that FNP could deliver siRNA to cells and improve siRNA knockdown efficiency. HaSCP-2 knockdown by FNP-siRNA in vivo hindered H. armigera growth and development. FNP could enhance RNAi efficiency to achieve pest control by SCP-2-targeted FNP-RNAi.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | - Rong Peng
- Correspondence: ; Tel.: +86-27-67867221
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2
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Gołębiowski M, Urbanek A, Pietrzak A, Naczk AM, Bojke A, Tkaczuk C, Stepnowski P. Effects of the entomopathogenic fungus Metarhizium flavoviride on the fat body lipid composition of Zophobas morio larvae (Coleoptera: Tenebrionidae). Naturwissenschaften 2020; 107:7. [PMID: 31900598 DOI: 10.1007/s00114-019-1662-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Revised: 12/05/2019] [Accepted: 12/14/2019] [Indexed: 02/04/2023]
Abstract
Insects employ different defense strategies against fungal infections and chemicals. We aimed to identify the lipid compositions of the fat body of Zophobas morio larvae before and after fungal infection with the entomopathogenic fungus Metarhizium flavoviride. We used gas chromatography-mass spectrometry to analyze lipid extracts of the fat body isolated of Z. morio 2, 5, and 7 days after fungal infection (treatment group) and compared it with the lipid extracts in a control group injected with physiological isotonic saline. In all the samples, fatty acids were the most abundant compound found in the fat body extracts, with hexadecanoic acid/C16:0 being the most abundant lipid. However, the types and concentrations of lipids changed after fungal infection, likely as an immune response. The most considerable changes occurred in the concentrations of long-chain fatty acids, i.e., hexadecanoic acid/C16:0, octadecenoic acid/C18:1, and octadecanoic acid/C18:0. Contents of methyl ester increased significantly after infection, but that of other esters, especially octanoic acid decyl ester/OADE, decreased on the 5th day after infection. To the best of our knowledge, this is the first detailed analysis of the changes in the lipid composition of the fat body of Z. morio larvae as a result of fungal infection. Our results suggest that entomopathogenic fungal infection affects the internal lipid composition of insects, potentially as a way of adjusting to such infection. These results can help understand infection processes and defense strategies of insects against fungal infection. Ultimately, they can contribute to the creation of more effective chemicals against pest insects.
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Affiliation(s)
- Marek Gołębiowski
- Department of Environmental Analysis, Laboratory of Analysis of Natural Compounds, Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308, Gdańsk, Poland.
| | - Aleksandra Urbanek
- Department of Invertebrate Zoology and Parasitology, Faculty of Biology, University of Gdańsk, Wita Stwosza 59, 80-308, Gdańsk, Poland
| | - Anna Pietrzak
- Department of Invertebrate Zoology and Parasitology, Faculty of Biology, University of Gdańsk, Wita Stwosza 59, 80-308, Gdańsk, Poland
| | - Aleksandra M Naczk
- Department of Molecular Evolution, Faculty of Biology, University of Gdańsk, Wita Stwosza 59, 80-308, Gdańsk, Poland
| | - Aleksandra Bojke
- Department of Environmental Analysis, Laboratory of Analysis of Natural Compounds, Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308, Gdańsk, Poland
| | - Cezary Tkaczuk
- Department of Plant Protection and Breeding, Siedlce University of Natural Sciences and Humanities, B. Prusa 14, 08-110, Siedlce, Poland
| | - Piotr Stepnowski
- Department of Environmental Analysis, Laboratory of Chemical Environmental Risks, Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308, Gdańsk, Poland
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3
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Vanderplanck M, Decleves S, Roger N, Decroo C, Caulier G, Glauser G, Gerbaux P, Lognay G, Richel A, Escaravage N, Michez D. Is non-host pollen suitable for generalist bumblebees? INSECT SCIENCE 2018; 25:259-272. [PMID: 27731933 DOI: 10.1111/1744-7917.12410] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Revised: 08/29/2016] [Accepted: 09/20/2016] [Indexed: 05/25/2023]
Abstract
Current evidence suggests that pollen is both chemically and structurally protected. Despite increasing interest in studying bee-flower networks, the constraints for bee development related to pollen nutritional content, toxicity and digestibility as well as their role in the shaping of bee-flower interactions have been poorly studied. In this study we combined bioassays of the generalist bee Bombus terrestris on pollen of Cirsium, Trifolium, Salix, and Cistus genera with an assessment of nutritional content, toxicity, and digestibility of pollen. Microcolonies showed significant differences in their development, non-host pollen of Cirsium being the most unfavorable. This pollen was characterized by the presence of quite rare δ7-sterols and a low digestibility. Cirsium consumption seemed increase syrup collection, which is probably related to a detoxification mixing behavior. These results strongly suggest that pollen traits may act as drivers of plant selection by bees and partly explain why Asteraceae pollen is rare in bee generalist diet.
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Affiliation(s)
- Maryse Vanderplanck
- Laboratory of Zoology, Research Institute for Biosciences, University of Mons-UMONS, Mons, Belgium
| | - Sylvain Decleves
- Laboratory of Zoology, Research Institute for Biosciences, University of Mons-UMONS, Mons, Belgium
| | - Nathalie Roger
- Laboratory of Zoology, Research Institute for Biosciences, University of Mons-UMONS, Mons, Belgium
| | - Corentin Decroo
- Organic Synthesis and Mass Spectrometry Laboratory, Interdisciplinary Center for Mass Spectrometry, University of Mons-UMONS, Mons, Belgium
| | - Guillaume Caulier
- Research Institute for Biosciences, Biology of Marine Organisms and Biomimetics, University of Mons-UMONS, Mons, Belgium
| | - Gaetan Glauser
- Neuchâtel Platform of Analytical Chemistry, University of Neuchâtel, Neuchâtel, Switzerland
| | - Pascal Gerbaux
- Organic Synthesis and Mass Spectrometry Laboratory, Interdisciplinary Center for Mass Spectrometry, University of Mons-UMONS, Mons, Belgium
| | - Georges Lognay
- Laboratory of Analytical Chemistry, University of Liège, Gembloux Agro-Bio Tech, Gembloux
| | - Aurore Richel
- Unit of Biological and Industrial Chemistry (CBI), University of Liège, Gembloux Agro-Bio Tech, Gembloux, Belgium
| | - Nathalie Escaravage
- Laboratoire Evolution et Diversité Biologique (EDB), CNRS, ENFA, UMR 5174, Université Toulouse 3 Paul Sabatier, Toulouse, France
| | - Denis Michez
- Laboratory of Zoology, Research Institute for Biosciences, University of Mons-UMONS, Mons, Belgium
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Behmer ST. Overturning dogma: tolerance of insects to mixed-sterol diets is not universal. CURRENT OPINION IN INSECT SCIENCE 2017; 23:89-95. [PMID: 29129288 DOI: 10.1016/j.cois.2017.08.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Revised: 08/07/2017] [Accepted: 08/15/2017] [Indexed: 05/14/2023]
Abstract
Insects cannot synthesize sterols de novo, but like all eukaryotes they use them as cell membrane inserts where they influence membrane fluidity and rigidity. They also use a small amount for metabolic purposes, most notably as essential precursors for steroid hormones. It has been a long-held view that most insects require a small amount of specific sterol (often cholesterol) for metabolic purposes, but for membrane purposes (where the bulk of sterols are used) specificity in sterol structure was less important. Under this model, it was assumed that insects could tolerate mixed-sterol diets as long as a small amount of cholesterol was available. In the current paper this dogma is overturned, using data from plant-feeding insects that were fed mixed-sterol diets with different amounts and ratios of dietary sterols.
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Affiliation(s)
- Spencer T Behmer
- Department of Entomology, Texas A&M University, College Station, TX 77843, USA; Ecology & Evolutionary Biology Graduate Program, Texas A&M University, College Station, TX 77843, USA.
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Gołębiowski M, Cerkowniak M, Ostachowska A, Naczk AM, Boguś MI, Stepnowski P. Effect of Conidiobolus coronatus
on the Cuticular and Internal Lipid Composition of Tettigonia viridissima
Males. Chem Biodivers 2016; 13:982-9. [DOI: 10.1002/cbdv.201500316] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Accepted: 01/25/2016] [Indexed: 11/11/2022]
Affiliation(s)
- Marek Gołębiowski
- Laboratory of Analysis of Natural Compounds; Department of Environmental Analysis; Faculty of Chemistry; University of Gdańsk; ul. Wita Stwosza 63 80-308 Gdańsk Poland
| | - Magdalena Cerkowniak
- Laboratory of Analysis of Natural Compounds; Department of Environmental Analysis; Faculty of Chemistry; University of Gdańsk; ul. Wita Stwosza 63 80-308 Gdańsk Poland
| | - Aleksandra Ostachowska
- Laboratory of Analysis of Natural Compounds; Department of Environmental Analysis; Faculty of Chemistry; University of Gdańsk; ul. Wita Stwosza 63 80-308 Gdańsk Poland
| | - Aleksandra M. Naczk
- Department of Molecular Evolution; University of Gdańsk; ul. Wita Stwosza 59 80-308 Gdańsk Poland
| | - Mieczysława I. Boguś
- Institute of Parasitology; Polish Academy of Sciences; Twarda 51/55 00-818 Warszawa Poland
| | - Piotr Stepnowski
- Laboratory of Chemical Environmental Risks; Department of Environmental Analysis; Faculty of Chemistry; University of Gdańsk; ul. Wita Stwosza 63 80-308 Gdańsk Poland
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6
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Gołębiowski M, Cerkowniak M, Boguś MI, Włóka E, Przybysz E, Stepnowski P. Developmental changes in the sterol composition and the glycerol content of cuticular and internal lipids of three species of flies. Chem Biodivers 2014; 10:1521-30. [PMID: 23939800 DOI: 10.1002/cbdv.201200419] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2012] [Indexed: 11/08/2022]
Abstract
The glycerol concentration and the composition of cuticular and internal sterols in three medically and forensically important fly species, viz., Musca domestica, Sarcophaga carnaria, and Calliphora vicina, were analyzed. The cuticular and internal lipid extracts were separated by HPLC-LLSD, after which the sterol fraction was characterized by GC/MS in total ion current (TIC) mode. The cuticular lipids of M. domestica larvae contained seven sterols, while in pupae and females, six sterols were identified. Five sterols were found in the cuticular lipids of M. domestica males. The internal lipids of M. domestica larvae and pupae contained six and seven sterols, respectively, while those of male and female flies contained only five sterols. Sitosterol, cholesterol, and campesterol were the dominant sterols in M. domestica, while campestanol, stigmasterol, sitostanol, and fucosterol were identified in low concentrations or in traces. In contrast, cuticular and internal lipids of S. carnaria and C. vicina contained only cholesterol. Glycerol was identified in all stages of M. domestica, S. carnaria, and C. vicina. For all the three examined fly species, the present study clearly showed species-specific developmental changes in the composition of cuticular and internal sterols as well as in the glycerol concentration.
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Affiliation(s)
- Marek Gołębiowski
- Institute for Environmental and Human Health Protection, Faculty of Chemistry, University of Gdańsk, ul. Sobieskiego 18/19, PL-80-952 Gdańsk
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7
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Patkar P, Haubrich BA, Qi M, Nguyen TTM, Thomas CD, Nes WD. C-24-methylation of 26-fluorocycloartenols by recombinant sterol C-24-methyltransferase from soybean: evidence for channel switching and its phylogenetic implications. Biochem J 2013; 456:253-62. [PMID: 23984880 DOI: 10.1042/bj20121818] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The tightly coupled nature of the electrophilic alkylation reaction sequence catalysed by 24-SMT (sterol C-24-methyltransferase) of land plants and algae can be distinguished by the formation of cationic intermediates that yield phyla-specific product profiles. C-24-methylation of the cycloartenol substrate by the recombinant Glycine max (soybean) 24-SMT proceeds to a single product 24(28)-methylenecycloartanol, whereas the 24-SMT from green algae converts cycloartenol into two products cyclolaudenol [∆(25(27))-olefin] and 24(28)-methylenecycloartanol [(∆24(28))-olefin]. Substrate analogues that differed in the steric-electronic features at either end of the molecule, 26-homocycloartenol or 3β-fluorolanostadiene, were converted by G. max SMT into a single 24(28)-methylene product. Alternatively, incubation of the allylic 26-fluoro cyclosteroid with G. max SMT afforded a bound intermediate that converted in favour of the ∆(25(27))-olefin product via the cyclolaudenol cation formed initially during the C-24-methylation reaction. A portion of the 26-fluorocycloartenol substrate was also intercepted by the enzyme and the corresponding hydrolysis product identified by GC-MS as 26-fluoro-25-hydroxy-24-methylcycloartanol. Finally, the 26-fluorocycloartenols are competitive inhibitors for the methylation of cycloartenol and 26-monofluorocycloartenol generated timedependent inactivation kinetics exhibiting a kinact value of 0.12 min(-1). The ability of soybean 24-SMT to generate a 25-hydroxy alkylated sterol and fluorinated ∆(25(27))-olefins is consistent with our hypothesis that (i) achieving the cyclolaudenyl cation intermediate by electrophilic alkylation of cycloartenol is significant to the overall reaction rate, and (ii) the evolution of variant sterol C-24-methylation patterns is driven by competing reaction channels that have switched in algae from formation of primarily ∆(25(27)) products that convert into ergosterol to, in land plants, formation of ∆(24(28)) products that convert into sitosterol.
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Affiliation(s)
- Presheet Patkar
- *Center for Chemical Biology and Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409, U.S.A
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8
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Jing X, Grebenok RJ, Behmer ST. Sterol/steroid metabolism and absorption in a generalist and specialist caterpillar: effects of dietary sterol/steroid structure, mixture and ratio. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2013; 43:580-7. [PMID: 23567589 DOI: 10.1016/j.ibmb.2013.03.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Revised: 03/23/2013] [Accepted: 03/26/2013] [Indexed: 06/02/2023]
Abstract
Insects cannot synthesize sterols de novo, so they typically require a dietary source. Cholesterol is the dominant sterol in most insects, but because plants contain only small amounts of cholesterol, plant-feeding insects generate most of their cholesterol by metabolizing plant sterols. Plants almost always contain mixtures of different sterols, but some are not readily metabolized to cholesterol. Here we explore, in two separate experiments, how dietary phytosterols and phytosteroids, in different mixtures, ratios, and amounts, affect insect herbivore sterol/steroid metabolism and absorption; we use two caterpillars species - one a generalist (Heliothis virescens), the other a specialist (Manduca sexta). In our first experiment caterpillars were reared on two tobacco lines - one expressing a typical phystosterol profile, the other expressing high amounts/ratios of stanols and 3-ketosteroids. Caterpillars reared on the control tobacco contained mostly cholesterol, but those reared on the modified tobacco had reduced amounts of cholesterol, and lower total sterol/steroid body profiles. In our second experiment, caterpillars were reared on artificial diets containing known amounts of cholesterol, stigmasterol, cholestanol and/or cholestanone, either singly or in various combinations and ratios. Cholesterol and stigmasterol-reared moths were mostly cholesterol, while cholestanol-reared moths were mostly cholestanol. Moth tissue cholesterol concentration tended to decrease as the ratio of dietary cholestanol and/or cholestanone increased. In both moths cholestanone was metabolized into cholestanol and epicholestanol. Interestingly, M. sexta generated much more cholestanol than epicholestanol, while H. virescens did the opposite. Finally, total tissue steroid levels were significantly reduced in moths reared on diets containing very high levels of cholestanol. We discuss how dietary sterol/steroid structural differences are important with respect to sterol/steroid metabolism and uptake, including species-specific differences.
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Affiliation(s)
- Xiangfeng Jing
- Department of Entomology, Texas A&M University, TAMU 2475, College Station, TX 77843, USA.
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Thakur A, Kaur S, Kaur A, Singh V. Enhanced resistance to Spodoptera litura in endophyte infected cauliflower plants. ENVIRONMENTAL ENTOMOLOGY 2013; 42:240-246. [PMID: 23575013 DOI: 10.1603/en12001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Endophytic fungi, which live within host plant tissues without causing any visible symptom of disease, are important mediators of plant-herbivore interactions. These endophytes enhance resistance of host plant against insect herbivores mainly by productions of various alkaloid based defensive compounds in the plant tissue or through alterations of plant nutritional quality. Two endophytic fungi, i.e., Nigrospora sp. and Cladosporium sp., were isolated from Tinospora cordifolia (Thunb.) Miers, a traditional indian medicinal plant. Cauliflower (Brassica oleracea L.) plants were inoculated with these two endophytic fungi. The effect of endophyte infected and uninfected cauliflower plants were measured on the survival and development of Spodoptera litura (Fab.), a polyphagous pest. Endophyte infected cauliflower plants showed resistance to S. litura in the form of significant increase in larval and pupal mortality in both the fungi. Inhibitory effects of endophytic fungi also were observed on adult emergence, longevity, reproductive potential, as well as hatchability of eggs. Thus, it is concluded that antibiosis to S. litura could be imparted by artificial inoculation of endophytes and this could be used to develop alternative ecologically safe control strategies.
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Affiliation(s)
- Abhinay Thakur
- Department of Zoology, Guru Nanak Dev University, Amritsar (Punjab), India
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10
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Bouvaine S, T Behmer S, Lin GG, Faure ML, Grebenok RJ, Douglas AE. The physiology of sterol nutrition in the pea aphid Acyrthosiphon pisum. JOURNAL OF INSECT PHYSIOLOGY 2012; 58:1383-9. [PMID: 22878342 DOI: 10.1016/j.jinsphys.2012.07.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2012] [Revised: 07/30/2012] [Accepted: 07/31/2012] [Indexed: 05/14/2023]
Abstract
The phloem sap of fava bean (Vicia faba) plants utilized by the pea aphid Acyrthosiphon pisum contains three sterols, cholesterol, stigmasterol and sitosterol, in a 2:2:1 ratio. To investigate the nutritional value of these sterols, pea aphids were reared on chemically-defined diets containing each sterol at 0.1, 1 and 10μgml(-1) with a sterol-free diet as control. Larval growth rate and aphid lifespan did not vary significantly across the diets, indicating that sterol reserves can buffer some performance indices against a shortfall in dietary sterol over at least one generation. However, lifetime reproductive output was depressed in aphids on diets containing stigmasterol or no sterol, relative to diets supplemented with cholesterol or sitosterol. The cholesterol density of embryos in teneral adults was significantly higher than in the total body; and the number and biomass of embryos in aphids on diets with stigmasterol and no sterols were reduced relative to diets with cholesterol or sitosterol, indicating that the reproductive output of the pea aphid can be limited by the amount and composition of dietary sterol. In a complementary RNA-seq analysis of pea aphids reared on plants and diets with different sterol contents, 7.6% of the 17,417 detected gene transcripts were differentially expressed. Transcript abundance of genes with annotated function in sterol utilization did not vary significantly among treatments, suggesting that the metabolic response to dietary sterol may be mediated primarily at the level of enzyme function or metabolite concentration.
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Affiliation(s)
- Sophie Bouvaine
- Department of Entomology, Cornell University, Comstock Hall, Ithaca, NY 14853, USA
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11
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Jing X, Vogel H, Grebenok RJ, Zhu-Salzman K, Behmer ST. Dietary sterols/steroids and the generalist caterpillar Helicoverpa zea: physiology, biochemistry and midgut gene expression. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2012; 42:835-45. [PMID: 22898624 DOI: 10.1016/j.ibmb.2012.07.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Revised: 07/09/2012] [Accepted: 07/25/2012] [Indexed: 05/16/2023]
Abstract
Sterols are essential nutrients for insects because, in contrast to mammals, no insect (or arthropod for that matter) can synthesize sterols de novo. Plant-feeding insects typically generate their sterols, commonly cholesterol, by metabolizing phytosterols. However, not all phytosterols are readily converted to cholesterol. In this study we examined, using artificial diets containing single sterols/steroids, how typical (cholesterol and stigmasterol) and atypical (cholestanol and cholestanone) sterols/steroids affect the performance of a generalist caterpillar (Helicoverpa zea). We also performed sterols/steroids analyses, using GC/MS techniques, to explore the metabolic fate of these different dietary sterols/steroids. Finally, we used a microarray approach to measure, and compare, midgut gene expression patterns that arise as a function of dietary sterols/steroids. In general, H. zea performed best on the cholesterol and stigmasterol diets, with cholesterol as the dominant tissue sterol on these two treatments. Compared to the cholesterol and stigmasterol diets, performance was reduced on the cholestanol and cholestanone diets; on these latter treatments stanols were the dominant tissue sterol. Finally, midgut gene expression patterns differed as a function of dietary sterol/steroid; using the cholesterol treatment as a reference, gene expression differences were smallest on stigmasterol, intermediate on cholestanol, and greatest on cholestanone. Inspection of our data revealed two broad insights. First, they identify a number of genes potentially involved in sterol/steroid metabolism and absorption. Second, they provide unique mechanistic insights into how variation in dietary sterol/steroid structure can affect insect herbivores.
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Affiliation(s)
- Xiangfeng Jing
- Department of Entomology, Texas A&M University, TAMU 2475, College Station, TX 77843-2475, USA.
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12
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Peng R, Fu Q, Hong H, Schwaegler T, Lan Q. THAP and ATF-2 regulated sterol carrier protein-2 promoter activities in the larval midgut of the yellow fever mosquito, Aedes aegypti. PLoS One 2012; 7:e46948. [PMID: 23056538 PMCID: PMC3464256 DOI: 10.1371/journal.pone.0046948] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2012] [Accepted: 09/10/2012] [Indexed: 11/29/2022] Open
Abstract
Expression of sterol carrier protein-2 (SCP-2) in Aedes aegypti shows a distinct temporal/spatial pattern throughout the life cycle. In order to identify the transcription factors responsible for the larval temporal/spatial regulation of AeSCP-2 transcription, AeSCP-2 promoter activities were studied in vivo via transient transfection of promoter/reporter gene assays. Regulatory sequences upstream −1.3 kb of the transcription start site of AeSCP-2 were found to be critical for the in vivo temporal/spatial promoter activity. Interestingly, the −1.6 kb promoter sequence efficiently drove the larval midgut-specific siRNA expression, indicating that the −1.6 kb upstream sequence is sufficient for temporal/spatial AeSCP-2 transcriptional activity. Four transcription factors were identified in the midgut nuclear extract from feeding larvae via labeled −1.6/−1.3 kb DNA probe pull-down and proteomic analysis. Co-transfection of the promoter/reporter gene with inducible siRNA expression of each transcription factor was performed to confirm the regulatory function of individual transcription factor on AeSCP-2 transcriptional activities in the larval midgut. The results indicate that two of the identified transcription factors, Thanatos-associated protein (THAP) and activating transcription factor-2 (ATF-2), antagonistically control AeSCP-2 transcriptional activity in the midgut of feeding larvae via the regulatory sequences between −1.6 to −1.3 kb 5′ upstream of the transcription start site. In vivo expression knockdown of THAP and ATF-2 resulted in significant changes in developmental progression, which may be partially due to their effects on AeSCP-2 expression.
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Affiliation(s)
- Rong Peng
- College of Life Sciences, Central China Normal University, Wuhan, Hubei, China
- * E-mail: (RP); (QL)
| | - Qiang Fu
- Department of Entomology, University of Wisconsin, Madison, Wisconsin, United States of America
| | - Huazhu Hong
- College of Life Sciences, Central China Normal University, Wuhan, Hubei, China
| | - Tyler Schwaegler
- Department of Entomology, University of Wisconsin, Madison, Wisconsin, United States of America
| | - Que Lan
- Department of Entomology, University of Wisconsin, Madison, Wisconsin, United States of America
- * E-mail: (RP); (QL)
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Raman A, Wheatley W, Popay A. Endophytic fungus-vascular plant-insect interactions. ENVIRONMENTAL ENTOMOLOGY 2012; 41:433-47. [PMID: 22732600 DOI: 10.1603/en11317] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Insect association with fungi has a long history. Theories dealing with the evolution of insect herbivory indicate that insects used microbes including fungi as their principal food materials before flowering plants evolved. Subtlety and the level of intricacy in the interactions between insects and fungi indicate symbiosis as the predominant ecological pattern. The nature of the symbiotic interaction that occurs between two organisms (the insect and the fungus), may be either mutualistic or parasitic, or between these two extremes. However, the triangular relationship involving three organisms, viz., an insect, a fungus, and a vascular plant is a relationship that is more complicated than what can be described as either mutualism or parasitism, and may represent facets of both. Recent research has revealed such a complex relationship in the vertically transmitted type-I endophytes living within agriculturally important grasses and the pestiferous insects that attack them. The intricacy of the association depends on the endophytic fungus-grass association and the insect present. Secondary compounds produced in the endophytic fungus-grass association can provide grasses with resistance to herbivores resulting in mutualistic relationship between the fungus and the plant that has negative consequences for herbivorous insects. The horizontally transmitted nongrass type-II endophytes are far less well studied and as such their ecological roles are not fully understood. This forum article explores the intricacy of dependence in such complex triangular relationships drawing from well-established examples from the fungi that live as endophytes in vascular plants and how they impact on the biology and evolution of free-living as well as concealed (e.g., gall-inducing, gall-inhabiting) insects. Recent developments with the inoculation of strains of type-I fungal endophytes into grasses and their commercialization are discussed, along with the possible roles the endophytic fungi play in the galls induced by the Cecidomyiidae (Diptera).
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Affiliation(s)
- A Raman
- Charles Sturt University & E H Graham Centre for Agricultural Innovation, Orange, New South Wales 2800, Australia.
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Jing X, Grebenok RJ, Behmer ST. Plant sterols and host plant suitability for generalist and specialist caterpillars. JOURNAL OF INSECT PHYSIOLOGY 2012; 58:235-44. [PMID: 22154836 DOI: 10.1016/j.jinsphys.2011.11.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2011] [Revised: 11/15/2011] [Accepted: 11/17/2011] [Indexed: 05/16/2023]
Abstract
Insects, unlike plants and vertebrates, lack the ability to biosynthesize sterols. Cholesterol is typically the most common sterol found in plant-feeding insects, but it is rarely found in plants above trace levels, so plant-feeding insects must produce the cholesterol they need by metabolizing the sterols found in the plants they eat. Plant-feeding insects are, however, often limited in terms of which sterols can be converted to cholesterol. In the current study we used a transgenic tobacco plant line that displays high levels of atypical plant steroids, specifically stanols and ketone-steroids, to explore how novel steroid structural features affect performance in three economically important caterpillars (Heliothis virescens, Spodoptera exigua, and Manduca sexta). For each species we measured pupation success, larval development, pupal mass, pupal development, and eclosion success. For the two generalists species (H. virescens and S. exigua) we also measured egg production and egg viability. We then used these eggs to replicate the experiment, so that we could examine the effect of parental steroid dietary history on survival, growth and reproduction of 2nd-generation individuals. Significant negative effects of novel steroids on larval and pupal performance were observed for each caterpillar in the first generation, although these were often subtle, and were not consistent between the three species. In the second generation, larval survival estimated by 'pupation number/plant' on the tobacco plants with novel steroids was significantly reduced, while eclosion success was significantly lower for H. virescens. With respect to adult reproduction (i.e. egg production and egg viability) there were no observed differences in the first generation, but novel steroids significantly negatively impacted reproduction in the second generation. The findings from this study, when integrated into a simple population growth model, demonstrate the potential in using plants with modified steroids as a novel approach to manage populations of economically important caterpillar species.
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Affiliation(s)
- Xiangfeng Jing
- Department of Entomology, Texas A&M University, College Station, TX 77843-2475, USA.
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Behmer ST, Grebenok RJ, Douglas AE. Plant sterols and host plant suitability for a phloem-feeding insect. Funct Ecol 2010. [DOI: 10.1111/j.1365-2435.2010.01810.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Kumar RB, Shanmugapriya B, Thiyagesan K, Kumar SR, Xavier SM. A search for mosquito larvicidal compounds by blocking the sterol carrying protein, AeSCP-2, through computational screening and docking strategies. Pharmacognosy Res 2010; 2:247-53. [PMID: 21808576 PMCID: PMC3141136 DOI: 10.4103/0974-8490.69126] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2010] [Revised: 05/22/2010] [Accepted: 09/07/2010] [Indexed: 11/04/2022] Open
Abstract
BACKGROUND Sterol is a very vital compound for most of the insects and mosquitoes to complete their life cycle. Unfortunately mosquitoes cannot synthesize the sterol, it depends on mammals for the same. Mosquitoes take the sterol from the plant decays during their larval stage in the form of phytosterol, which is then converted to cholesterol for further growth and reproduction. This conversion occurs with the help of the sterol carrier protein 2(SCP2). METHODS Mosquito populations are controlled by plant-based inhibitors, which inhibit sterol carrier protein (SCPI-Sterol carrier protein inhibitor) activity. In this article, we explain the methods of inhibiting Aedes aegypti SCP2 by insilico methods including natural inhibitor selection and filtrations by virtual screening and interaction studies. RESULTS In this study protein-ligand interactions were carried out with various phytochemicals, as a result of virtual screening Alpha-mangostin and Panthenol were found to be good analogs, and were allowed to dock with the mosquito cholesterol carrier protein AeSCP-2. CONCLUSION Computational selections of SCPIs are highly reliable and novel methods for discovering new and more effective compounds to control mosquitoes.
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Affiliation(s)
- R. Barani Kumar
- Department of Bioinformatics, Sathyabama University, Chennai-600 119, India.
| | | | - K. Thiyagesan
- Department of Zoology and Division of Wildlife Biology, A.V.C. College, Mayiladuthurai -609305, India.
| | - S. Raj Kumar
- Department of Zoology and Division of Wildlife Biology, A.V.C. College, Mayiladuthurai -609305, India.
| | - Suresh M. Xavier
- Department of Bioinformatics, Sathyabama University, Chennai-600 119, India.
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Vyazunova I, Lan Q. Yellow fever mosquito sterol carrier protein-2 gene structure and transcriptional regulation. INSECT MOLECULAR BIOLOGY 2010; 19:205-215. [PMID: 20002221 PMCID: PMC2862845 DOI: 10.1111/j.1365-2583.2009.00959.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
AeSCP-2, a sterol carrier protein, is involved in sterol trafficking in mosquitoes. The activity of the AeSCP-2 gene is important for mosquito development. An earlier study demonstrated that the transcription of this gene was upregulated by 20-hydroxyecdysone (20E) in cultured gut tissues. To investigate 20E-regulated transcription of the AeSCP-2 gene we truncated the upstream flanking region of AeSCP-2 gene and linked it to a reporter gene. The mosquito Aag-2 cell line was transfected with these promoter/reporter constructs and treated with 20E at various concentrations. Expression vectors of different transcription factors such as HR3 and beta FTZ-F1 were also co-transfected with the AeSCP-2 promoter/reporter constructs. The observed results demonstrated that varied combinations of transcription factors produce different promoter activities of the AeSCP-2 gene. This observation leads us to the conclusion that the partnership of transcription factors is crucial in regulating the transcriptional activity of the AeSCP-2 gene.
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Affiliation(s)
| | - Que Lan
- Correspondent author Department of Entomology, University of Wisconsin-Madison, Madison, WI 53706, Telephone: (608) 263-7924, Fax: (608) 262-3322,
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Guo XR, Zheng SC, Liu L, Feng QL. The sterol carrier protein 2/3-oxoacyl-CoA thiolase (SCPx) is involved in cholesterol uptake in the midgut of Spodoptera litura: gene cloning, expression, localization and functional analyses. BMC Mol Biol 2009; 10:102. [PMID: 19912624 PMCID: PMC2779813 DOI: 10.1186/1471-2199-10-102] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2009] [Accepted: 11/13/2009] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Sterol carrier protein-2/3-oxoacyl-CoA thiolase (SCPx) gene has been suggested to be involved in absorption and transport of cholesterol. Cholesterol is a membrane component and is a precursor of ecdysteroids, but cannot be synthesized de novo in insects. However, a direct association between SCPx gene expression, cholesterol absorption and development in lepidopteran insects remains to be experimentally demonstrated. RESULTS An SCPx cDNA (SlSCPx) cloned from the common cutworm, Spodoptera litura, was characterized. The SlSCPx cDNA encoded a 535-amino acid protein consisting of a 3-oxoacyl-CoA thiolase (SCPx-t) domain and a SCP-2 (SCPx-2) domain. SlSCPx mRNA was expressed predominately in the midgut, while SlSCPx-2 mRNA was detected in the midgut, fat body and epidermis and no SlSCPx-t mRNA was detected. A 58-kDa full-length SCPx protein and a 44-kDa SCPx-t protein were detected in the midgut of sixth instar larvae when the anti-SlSCPx-t antibody was used in western blotting analysis; a 16-kDa SCP-2 protein was detected when anti-SlSCPx-2 antibody was used. SlSCPx protein was post-translationally cleaved into two smaller proteins, SCPx-t and SCPx-2. The gene appeared to be expressed into two forms of mRNA transcripts, which were translated into the two proteins, respectively. SlSCPx-t and SlSCPx-2 proteins have distinct and different locations in the midgut of sixth instar larvae. SlSCPx and SlSCPx-t proteins were detected predominately in the cytoplasm, whereas SlSCPx-2 protein was detected in the cytoplasm and nuclei in the Spli-221 cells. Over-expression of SlSCPx and SlSCPx-2 proteins enhanced cholesterol uptake into the Spli-221 cells. Knocking-down SlSCPx transcripts by dsRNA interference resulted in a decrease in cholesterol level in the hemolymph and delayed the larval to pupal transition. CONCLUSION Spatial and temporal expression pattern of this SlSCPx gene during the larval developmental stages of S. litura showed its specific association with the midgut at the feeding stage. Over-expression of this gene increased cholesterol uptake and interference of its transcript decreased cholesterol uptake and delayed the larval to pupal metamorphosis. All of these results taken together suggest that this midgut-specific SlSCPx gene is important for cholesterol uptake and normal development in S. litura.
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Affiliation(s)
- Xing-Rong Guo
- Guangdong Provincial Key Lab of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou, 510631, PR China
- The Faculty of Pharmacy and Laboratory Medicine, Yunyang Medical College, Hubei, 442000, PR China
| | - Si-Chun Zheng
- Guangdong Provincial Key Lab of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou, 510631, PR China
| | - Lin Liu
- Guangdong Provincial Key Lab of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou, 510631, PR China
| | - Qi-Li Feng
- Guangdong Provincial Key Lab of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou, 510631, PR China
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Gong J, Hou Y, Zha XF, Lu C, Zhu Y, Xia QY. Molecular cloning and characterization ofBombyx moristerol carrier protein x/sterol carrier protein 2 (SCPx/SCP2) gene. ACTA ACUST UNITED AC 2009; 17:326-33. [PMID: 17343205 DOI: 10.1080/10425170600886706] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Cholesterol transport is a very important process in insect. We have isolated the Bombyx mori sterol carrier protein x (BmSCPx) cDNA and sterol carrier protein 2 (BmSCP2) cDNA: a 1.7 kb clone encoding SCPx, a 3-ketoacyl CoA thiolase, and 0.6 kb clone presumably encoding SCP2, which is thought to be an intracellular lipid transfer protein. Interestingly, the identical gene SCPx/SCP2 encodes the two types of transcripts by alternative splicing mechanism in Bombyx mori. The SCPx mRNA spans two exons in genome, and conceptual translation of the SCPx cDNA encodes a protein of 536 amino acids, which contains a thiolase domain and a SCP2 domain. Whereas the SCP2 mRNA partly lakes the first exon, and the SCP2 is a 146 amino acids containing a SCP2 domain only. Both BmSCPx and BmSCP2 have a putative peroxisomal targeting signal in the C-terminal region. BmSCPx shares 94 and 72% similarity to Spodoptera littoralis SCPx and human SCPx, respectively. RT-PCR analysis reveals that transcripts of BmSCP2 were detected in all tissues analyzed. BmSCPx transcription expressed only in midgut and malpighian tubules. However, the BmSCPx and BmSCP2 express strong in midgut during the last instar larvae. The tissue-specific expression pattern of BmSCPx and BmSCP2 is consistent with a role for these proteins in cholesterol metabolism. The results suggest that SCPx/SCP2 may play a key role in sterol absorption and intracellular carrier in silkworm.
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Affiliation(s)
- Jing Gong
- Key Sericultural Laboratory of Agricultural Ministry, Southwest University, Chongqing 400715, People's Republic of China
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Plant Sterol Methyltransferases: Phytosterolomic Analysis, Enzymology, and Bioengineering Strategies. BIOENGINEERING AND MOLECULAR BIOLOGY OF PLANT PATHWAYS 2008. [DOI: 10.1016/s1755-0408(07)01009-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Blitzer EJ, Vyazunova I, Lan Q. Functional analysis of AeSCP-2 using gene expression knockdown in the yellow fever mosquito, Aedes aegypti. INSECT MOLECULAR BIOLOGY 2005; 14:301-7. [PMID: 15926899 DOI: 10.1111/j.1365-2583.2005.00560.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
The effect of gene expression knockdown was used to study the function of the sterol carrier protein-2 (AeSCP-2) in the yellow fever mosquito, Aedes aegypti. Injection of small double stranded AeSCP-2 RNAs into mosquito larvae resulted in the knockdown of gene products. The lack of AeSCP-2 in larvae coincided with a reduction in accumulated cholesterol in pupae, supporting the hypothesis that AeSCP-2 may be involved in cholesterol uptake in mosquito larvae. Knockdown of AeSCP-2 caused a high mortality rate in developing adult and reduced egg viability. Results from this study indicate that AeSCP-2 is important for adult development and for the viability of the eggs.
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Affiliation(s)
- E J Blitzer
- Department of Entomology, University of Wisconsin-Madison, Madison, WI 53706, USA
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Jallow MF, Dugassa-Gobena D, Vidal S. Indirect interaction between an unspecialized endophytic fungus and a polyphagous moth. Basic Appl Ecol 2004. [DOI: 10.1078/1439-1791-00224] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Dyer DH, Lovell S, Thoden JB, Holden HM, Rayment I, Lan Q. The structural determination of an insect sterol carrier protein-2 with a ligand-bound C16 fatty acid at 1.35-A resolution. J Biol Chem 2003; 278:39085-91. [PMID: 12855689 DOI: 10.1074/jbc.m306214200] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Yellow fever mosquito sterol carrier protein (SCP-2) is known to bind to cholesterol. We report here the three-dimensional structure of the complex of SCP-2 from Aedes aegypti with a C16 fatty acid to 1.35-A resolution. The protein fold is exceedingly similar to the human and rabbit proteins, which consist of a five-stranded beta-sheet that exhibits strand order 3-2-1-4-5 with an accompanying layer of four alpha-helices that cover the beta-sheet. A large cavity exists at the interface of the layer alpha-helices and the beta-sheet, which serves as the fatty acid binding site. The carboxylate moiety of the fatty acid is coordinated by a short loop that connects the first alpha-helix to the first beta-strand, whereas the acyl chain extends deep into the interior of the protein. Interestingly, the orientation of the fatty acid is opposite to the observed orientation for Triton X-100 in the SCP-2-like domain from the peroxisomal multifunctional enzyme (Haapalainen, A. M., van Aalten, D. M., Merilainen, G., Jalonen, J. E., Pirila, P., Wierenga, R. K., Hiltunen, J. K., and Glumoff, T. (2001) J. Mol. Biol. 313, 1127-1138). The present study suggests that the binding pocket in the SCP-2 family of proteins may exhibit conformational flexibility to allow coordination of a variety of lipids.
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Affiliation(s)
- David H Dyer
- Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706, USA
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Nasir H, Noda H. Yeast-like symbiotes as a sterol source in anobiid beetles (Coleoptera, Anobiidae): possible metabolic pathways from fungal sterols to 7-dehydrocholesterol. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2003; 52:175-182. [PMID: 12655605 DOI: 10.1002/arch.10079] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Insects are unable to synthesize sterols and require exogenous sterol sources for their normal development and reproduction. A few exceptions are insects associated with symbiotic yeasts or fungi. We analyzed sterols by GC-MS in two anobiid beetles (Lasioderma serricorne and Stegobium paniceum), their intracellular yeast-like symbiotes (YLS), and their diets in order to clarify the sterols synthesized by YLS and the metabolic pathways of the sterols in the beetles. Several C(27), C2(8), and C(29) saturated and unsaturated sterols were identified; the predominant sterols were cholesterol and 7-dehydrocholesterol in the anobiid beetles and ergosterol in the YLS. Most sterols detected in YLS were those known in the late pathway of the ergosterol biosynthesis in yeasts and most of the sterols in the beetles appear to be intermediate metabolites from YLS sterols to 7-dehydrocholesterol. The anobiid beetles appear to use ergosterol and 5-dihydroergosterol as sources for 7-dehydrocholesterol.
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Affiliation(s)
- Habib Nasir
- National Institute of Agrobiological Sciences, Ibaraki, Japan
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Krebs KC, Lan Q. Isolation and expression of a sterol carrier protein-2 gene from the yellow fever mosquito, Aedes aegypti. INSECT MOLECULAR BIOLOGY 2003; 12:51-60. [PMID: 12542635 DOI: 10.1046/j.1365-2583.2003.00386.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Trafficking of cholesterol in insects is a very important process due to the fact that insects depend on dietary cholesterol to fulfil their physiological needs. We identified a putative mosquito sterol carrier protein-2 (SCP-2) cDNA from fourth instar subtracted cDNA library. The AeSCP-2 protein has high degree homology in the sterol transfer domain to both rat and human SCP-2. Transcripts of AeSCP-2 in fourth instars were detected strongly in the midgut, and weakly in the head and hindgut. In the early pupae, AeSCP-2 transcription was observed in the thorax, head and body wall of abdomen, but not in the gut. The interaction of mosquito sterol carrier protein-2 (AeSCP-2) with cholesterol was examined. The Kd of purified recombinant AeSCP-2 to cholesterol was 5.6 +/- 0.6 x 10-9 m using radiolabelled cholesterol-binding assay. The results suggest that AeSCP-2 has high affinity to cholesterol and may function as a carrier protein in mosquitoes.
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Affiliation(s)
- K C Krebs
- Department of Entomology, University of Wisconsin-Madison, Madison, WI 53076, USA
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Marshall JA, Dennis AL, Kumazawa T, Haynes AM, Nes WD. Soybean sterol composition and utilization by Phytophthora sojae. PHYTOCHEMISTRY 2001; 58:423-8. [PMID: 11557074 DOI: 10.1016/s0031-9422(01)00219-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The sterol fraction of Glycine max (soybean) was found to contain a mixture of 13 major sterols which differed dramatically in composition between seeds and shoots. Typical C4-desmethyl Delta(5)-sterols, including sitosterol, predominate the sterol mixture of shoots, whereas C4-methyl sterol intermediates, cycloartenol and 24(28)-methylene cycloartanol, accumulate in seeds. The significance of modified sterol profile of shoot compared to seed was relevant to the physiology of Phytophthora sojae, a phytopathogen of soybean shown to be auxotrophic for sterol. Sterols native to the host plant containing a C4-methyl group, such as cycloartenol, were not utilized by the fungus. Alternatively, all Delta(5)-sterols added to the culture media of P. sojae supported normal growth and promoted viable oospore production. The results demonstrate the importance of sterols in plant-fungal interactions and offer the possibility of bioengineering the phytosterol pathway for resistance to phytopathogens which scavenge specific sterols of the host plant to complete the life cycle.
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Affiliation(s)
- J A Marshall
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409-1061, USA
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Abstract
The study of fat metabolism in insects has received considerable attention over the years. Although by no means complete, there is a growing body of information about dietary lipid requirements, and the absolute requirement for sterol is of particular note. In this review we (a) summarize the state of understanding of the dietary requirements for the major lipids and (b) describe in detail the insect lipid transport system. Insects digest and absorb lipids similarly to vertebrates, but with some important differences. The hallmark of fat metabolism in insects centers on the lipid transport system. The major lipid transported is diacylglycerol, and it is carried by a high-density lipoprotein called lipophorin. Lipophorin is a reusable shuttle that picks up lipid from the gut and delivers it to tissues for storage or utilization without using the endocytic processes common to vertebrate cells. The mechanisms by which this occurs are not completely understood and offer fruitful areas for future research.
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Affiliation(s)
- L E Canavoso
- Department of Biochemistry and Molecular Biophysics, and Center for Insect Science, University of Arizona, Tucson, Arizona 85721, USA.
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