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Richard Ian Samuels - One of the best experts on this subject based on the ideXlab platform.
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digestive enzymes in larvae of the leaf cutting ant acromyrmex subterraneus hymenoptera formicidae attini
Journal of Insect Physiology, 2007Co-Authors: Milton Erthal, Carlos P Silva, Richard Ian SamuelsAbstract:The digestive physiology and biochemistry of larvae of the leaf-cutting ant Acromyrmex subterraneus were investigated here. The activity of digestive enzymes was evaluated in the Labial Glands, midgut epithelium (soluble and particulate fractions), and in the lumen contents, separated into endo and ectoperitrophic regions. Enzymes with high levels of activity were partially characterised using chromatography and electrophoresis techniques. Microscope observations were carried out and the anatomy of the larval digestive tract was described here for the first time. Larvae fed with pH indicator solutions showed the anterior portion of the midgut to be acidic and the posterior portion neutral to alkaline, indicating that the pH of the different regions of the midgut could optimise certain enzyme activities, whilst inhibiting others. The flow rate of the intestinal contents was also evaluated in larvae fed with a dye solution. The slow flow rate is probably due to closure of the rear end of the larval midgut. No compartmentalisation of digestive enzymes acting on oligosaccharides and disaccharides in the ectoperitrophic space and on polysaccharides in the endoperitrophic space was observed here, which could also be related to the closure of the midgut. The digestive physiology of these larvae is therefore similar to ancestral Holometabola, a paradox when considering the highly evolved nature of these insects. The larval midgut demonstrated a large diversity of enzyme activities with high levels of α-amylase, α-mannosidase, chitinase, α-glucosidase, β-glucosidase and proteinase. High levels of chitinase and amylase activities were detected in the Labial Glands of larvae. The enzyme profile reflected the necessity of the larvae to degrade the fungal substrate, their sole diet, and a probable source of some of the digestive enzymes detected here. When compared to adults, the larvae had a greater diversity and higher levels of enzyme activity, highlighting their importance as the “digestive caste” of the colony.
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digestive enzymes of leaf cutting ants acromyrmex subterraneus hymenoptera formicidae attini distribution in the gut of adult workers and partial characterization
Journal of Insect Physiology, 2004Co-Authors: Milton Erthal, Carlos P Silva, Richard Ian SamuelsAbstract:Abstract Enzyme activities associated with the Labial Glands, midgut and rectum of adult Acromyrmex subterraneus were investigated in order to understand their role in digestion of plant and fungal material. High chitinolytic activity was detected in the Labial Glands, indicating a possible role in the degradation of fungus ingested by the ants. Chitinolytic activity seen in other compartments of the alimentary canal probably originated in the Labial Glands. The highest activity detected in the midgut was for α -glucosidase, which was considered to be of insect origin due to its association with midgut epithelium and it is probably involved in glucose assimilation from nutrient sources such as maltose and sucrose present in plant material. A large range of enzyme activities were detected in the rectal lumen contents, and as in the midgut the highest values were for α -glucosidase activity. The absence of activity associated with the epithelium, in the particulate fraction, indicates that the rectal epithelium does not have a secretory function. The detection of enzymes in the rectal lumen contents, which were not detected in the midgut lumen contents, indicates that the rectum acts as a reservoir, accumulating enzymes. The major digestive enzymes were partially characterized using hydrophobic interaction chromatography, gel filtration and SDS-PAGE. The pH of the adult intestinal tract and flow rate of dye through the tract was investigated. A gradual acidification of the intestinal tract was noted commencing with the crop (pH 6−8.2) and terminating with the rectum (pH 3–5). The flow of dye through the different compartments of the tract showed a rapid fill time for all the gut compartments and a short residence time in the crop. In all other compartments, the dye remained detectable for 10 days or longer.
Milton Erthal - One of the best experts on this subject based on the ideXlab platform.
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digestive enzymes in larvae of the leaf cutting ant acromyrmex subterraneus hymenoptera formicidae attini
Journal of Insect Physiology, 2007Co-Authors: Milton Erthal, Carlos P Silva, Richard Ian SamuelsAbstract:The digestive physiology and biochemistry of larvae of the leaf-cutting ant Acromyrmex subterraneus were investigated here. The activity of digestive enzymes was evaluated in the Labial Glands, midgut epithelium (soluble and particulate fractions), and in the lumen contents, separated into endo and ectoperitrophic regions. Enzymes with high levels of activity were partially characterised using chromatography and electrophoresis techniques. Microscope observations were carried out and the anatomy of the larval digestive tract was described here for the first time. Larvae fed with pH indicator solutions showed the anterior portion of the midgut to be acidic and the posterior portion neutral to alkaline, indicating that the pH of the different regions of the midgut could optimise certain enzyme activities, whilst inhibiting others. The flow rate of the intestinal contents was also evaluated in larvae fed with a dye solution. The slow flow rate is probably due to closure of the rear end of the larval midgut. No compartmentalisation of digestive enzymes acting on oligosaccharides and disaccharides in the ectoperitrophic space and on polysaccharides in the endoperitrophic space was observed here, which could also be related to the closure of the midgut. The digestive physiology of these larvae is therefore similar to ancestral Holometabola, a paradox when considering the highly evolved nature of these insects. The larval midgut demonstrated a large diversity of enzyme activities with high levels of α-amylase, α-mannosidase, chitinase, α-glucosidase, β-glucosidase and proteinase. High levels of chitinase and amylase activities were detected in the Labial Glands of larvae. The enzyme profile reflected the necessity of the larvae to degrade the fungal substrate, their sole diet, and a probable source of some of the digestive enzymes detected here. When compared to adults, the larvae had a greater diversity and higher levels of enzyme activity, highlighting their importance as the “digestive caste” of the colony.
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digestive enzymes of leaf cutting ants acromyrmex subterraneus hymenoptera formicidae attini distribution in the gut of adult workers and partial characterization
Journal of Insect Physiology, 2004Co-Authors: Milton Erthal, Carlos P Silva, Richard Ian SamuelsAbstract:Abstract Enzyme activities associated with the Labial Glands, midgut and rectum of adult Acromyrmex subterraneus were investigated in order to understand their role in digestion of plant and fungal material. High chitinolytic activity was detected in the Labial Glands, indicating a possible role in the degradation of fungus ingested by the ants. Chitinolytic activity seen in other compartments of the alimentary canal probably originated in the Labial Glands. The highest activity detected in the midgut was for α -glucosidase, which was considered to be of insect origin due to its association with midgut epithelium and it is probably involved in glucose assimilation from nutrient sources such as maltose and sucrose present in plant material. A large range of enzyme activities were detected in the rectal lumen contents, and as in the midgut the highest values were for α -glucosidase activity. The absence of activity associated with the epithelium, in the particulate fraction, indicates that the rectal epithelium does not have a secretory function. The detection of enzymes in the rectal lumen contents, which were not detected in the midgut lumen contents, indicates that the rectum acts as a reservoir, accumulating enzymes. The major digestive enzymes were partially characterized using hydrophobic interaction chromatography, gel filtration and SDS-PAGE. The pH of the adult intestinal tract and flow rate of dye through the tract was investigated. A gradual acidification of the intestinal tract was noted commencing with the crop (pH 6−8.2) and terminating with the rectum (pH 3–5). The flow of dye through the different compartments of the tract showed a rapid fill time for all the gut compartments and a short residence time in the crop. In all other compartments, the dye remained detectable for 10 days or longer.
Gary W Felton - One of the best experts on this subject based on the ideXlab platform.
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host plant driven transcriptome plasticity in the salivary Glands of the cabbage looper trichoplusia ni
PLOS ONE, 2017Co-Authors: Loren J Riveravega, David A Galbraith, Christina M Grozinger, Gary W FeltonAbstract:Generalist herbivores feed on a wide array of plants and need to adapt to varying host qualities and defenses. One of the first insect derived secretions to come in contact with the plant is the saliva. Insect saliva is potentially involved in both the pre-digestion of the host plant as well as induction/suppression of plant defenses, yet how the salivary Glands respond to changes in host plant at the transcriptional level is largely unknown. The objective of this study was to determine how the Labial salivary gland transcriptome varies according to the host plant on which the insect is feeding. In order to determine this, cabbage looper (Trichoplusia ni) larvae were reared on cabbage, tomato, and pinto bean artificial diet. Labial Glands were dissected from fifth instar larvae and used to extract RNA for RNASeq analysis. Assembly of the resulting sequencing reads resulted in a transcriptome library for T. ni salivary Glands consisting of 14,037 expressed genes. Feeding on different host plant diets resulted in substantial remodeling of the gland transcriptomes, with 4,501 transcripts significantly differentially expressed across the three treatment groups. Gene expression profiles were most similar between cabbage and artificial diet, which corresponded to the two diets on which larvae perform best. Expression of several transcripts involved in detoxification processes were differentially expressed, and transcripts involved in the spliceosome pathway were significantly downregulated in tomato-reared larvae. Overall, this study demonstrates that the transcriptomes of the salivary Glands of the cabbage looper are strongly responsive to diet. It also provides a foundation for future functional studies that can help us understand the role of saliva of chewing insects in plant-herbivore interactions.
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ablation of caterpillar Labial salivary Glands technique for determining the role of saliva in insect plant interactions
Journal of Chemical Ecology, 2006Co-Authors: Richard O Musser, Michelle Peiffer, Edward E Farmer, Spencer A Williams, Gary W FeltonAbstract:There has been an ardent interest in herbivore saliva due to its roles in inducing plant defenses and its impact on herbivore fitness. Two techniques are described that inhibit the secretion of Labial saliva from the caterpillar, Helicoverpa zea, during feeding. The methods rely on cauterizing the caterpillar's spinneret, the principal secretory structure of the Labial Glands, or surgically removing the Labial salivary gland. Both methods successfully inhibit secretion of saliva and the principal salivary enzyme glucose oxidase. Caterpillars with inhibited saliva production feed at similar rates as the untreated caterpillars, pupate, and emerge as adults. Glucose oxidase has been suggested to increase the caterpillar's survival through the suppression of inducible anti-herbivore defenses in plants. Tobacco (Nicotiana tabacum) leaves fed on by caterpillars with ablated salivary Glands had significantly higher levels of nicotine, an inducible anti-herbivore defense compound of tobacco, than leaves fed upon by caterpillars with intact Labial salivary Glands. Tomato (Lycopersicon esculentum) leaves fed upon by caterpillars with suppressed salivary secretions showed greatly reduced evidence of hydrogen peroxide formation compared to leaves fed upon by intact caterpillars. These two methods are useful techniques for determining the role that saliva plays in manipulating plant anti-herbivore defenses.
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the host plant as a factor in the synthesis and secretion of salivary glucose oxidase in larval helicoverpa zea
Archives of Insect Biochemistry and Physiology, 2005Co-Authors: Michelle Peiffer, Gary W FeltonAbstract:We investigated the effect of the host plant on the synthesis and secretion of the elicitor glucose oxidase in the salivary Glands of larval Helicoverpa zea. Glucose oxidase catalyses the oxidation of d-glucose to produce d-gluconic acid and hydrogen peroxide. Previous studies have found that the product hydrogen peroxide is primarily responsible for suppressing the wound-inducible defenses of the host plant. Using an antibody specific for glucose oxidase, we determined the effect of the host plant on the rate of secretion of glucose oxidase. Larval H. zea secrete microgram amounts of the enzyme glucose oxidase from their principal salivary Glands, the Labial Glands. Larvae reared on different host plants produce varying amounts of glucose oxidase in their Labial Glands. We used a tissue printing procedure with our antibody to determine if larvae secrete glucose oxidase directly at the feeding or wound sites. Significant amounts of the enzyme are deposited at the feeding site, although some is deposited outside the feeding margins. Arch. Insect Biochem. Physiol. 58:106–113, 2005. © 2005 Wiley-Liss, Inc.
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salivary glucose oxidase multifunctional roles for helicoverpa zea
Archives of Insect Biochemistry and Physiology, 1999Co-Authors: Herbert Eichenseer, Claravon M Mathews, Jian L Bi, Brad J Murphy, Gary W FeltonAbstract:Labial Glands of Helicoverpa zea produced a glucose oxidase (GOX), which was present in the saliva and midgut lumen. We purified GOX 23-fold by isoelectric focusing of Labial gland homogenates and investigated physical and kinetic properties of the enzyme. D-glucose and 6-deoxy-D-glucose were the optimal substrates of 22 carbohydrates tested with GOX. The enzyme was not inhibited by several inhibitors of fungal GOX but was sensitive to HgCl2. Labial gland GOX activities varied daily during larval development with highest activities found when larvae were actively feeding. Based on pH optimum, pI, molecular weight estimate and Km(glucose), the insect enzyme is not derived from fungal GOXs but appears to have similar kinetic and physical attributes to other insect GOXs. Some possible functions are discussed, including antimicrobial properties, manipulating midgut O2 levels, altering host plant defense responses, and metabolizing carbohydrates. Arch. Insect Biochem. Physiol. 42:99n109, 1999. ' 1999 Wiley-Liss, Inc.
Carlos P Silva - One of the best experts on this subject based on the ideXlab platform.
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digestive enzymes in larvae of the leaf cutting ant acromyrmex subterraneus hymenoptera formicidae attini
Journal of Insect Physiology, 2007Co-Authors: Milton Erthal, Carlos P Silva, Richard Ian SamuelsAbstract:The digestive physiology and biochemistry of larvae of the leaf-cutting ant Acromyrmex subterraneus were investigated here. The activity of digestive enzymes was evaluated in the Labial Glands, midgut epithelium (soluble and particulate fractions), and in the lumen contents, separated into endo and ectoperitrophic regions. Enzymes with high levels of activity were partially characterised using chromatography and electrophoresis techniques. Microscope observations were carried out and the anatomy of the larval digestive tract was described here for the first time. Larvae fed with pH indicator solutions showed the anterior portion of the midgut to be acidic and the posterior portion neutral to alkaline, indicating that the pH of the different regions of the midgut could optimise certain enzyme activities, whilst inhibiting others. The flow rate of the intestinal contents was also evaluated in larvae fed with a dye solution. The slow flow rate is probably due to closure of the rear end of the larval midgut. No compartmentalisation of digestive enzymes acting on oligosaccharides and disaccharides in the ectoperitrophic space and on polysaccharides in the endoperitrophic space was observed here, which could also be related to the closure of the midgut. The digestive physiology of these larvae is therefore similar to ancestral Holometabola, a paradox when considering the highly evolved nature of these insects. The larval midgut demonstrated a large diversity of enzyme activities with high levels of α-amylase, α-mannosidase, chitinase, α-glucosidase, β-glucosidase and proteinase. High levels of chitinase and amylase activities were detected in the Labial Glands of larvae. The enzyme profile reflected the necessity of the larvae to degrade the fungal substrate, their sole diet, and a probable source of some of the digestive enzymes detected here. When compared to adults, the larvae had a greater diversity and higher levels of enzyme activity, highlighting their importance as the “digestive caste” of the colony.
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digestive enzymes of leaf cutting ants acromyrmex subterraneus hymenoptera formicidae attini distribution in the gut of adult workers and partial characterization
Journal of Insect Physiology, 2004Co-Authors: Milton Erthal, Carlos P Silva, Richard Ian SamuelsAbstract:Abstract Enzyme activities associated with the Labial Glands, midgut and rectum of adult Acromyrmex subterraneus were investigated in order to understand their role in digestion of plant and fungal material. High chitinolytic activity was detected in the Labial Glands, indicating a possible role in the degradation of fungus ingested by the ants. Chitinolytic activity seen in other compartments of the alimentary canal probably originated in the Labial Glands. The highest activity detected in the midgut was for α -glucosidase, which was considered to be of insect origin due to its association with midgut epithelium and it is probably involved in glucose assimilation from nutrient sources such as maltose and sucrose present in plant material. A large range of enzyme activities were detected in the rectal lumen contents, and as in the midgut the highest values were for α -glucosidase activity. The absence of activity associated with the epithelium, in the particulate fraction, indicates that the rectal epithelium does not have a secretory function. The detection of enzymes in the rectal lumen contents, which were not detected in the midgut lumen contents, indicates that the rectum acts as a reservoir, accumulating enzymes. The major digestive enzymes were partially characterized using hydrophobic interaction chromatography, gel filtration and SDS-PAGE. The pH of the adult intestinal tract and flow rate of dye through the tract was investigated. A gradual acidification of the intestinal tract was noted commencing with the crop (pH 6−8.2) and terminating with the rectum (pH 3–5). The flow of dye through the different compartments of the tract showed a rapid fill time for all the gut compartments and a short residence time in the crop. In all other compartments, the dye remained detectable for 10 days or longer.
Irena Valterová - One of the best experts on this subject based on the ideXlab platform.
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characterization of neutral lipase bt 1 isolated from the Labial gland of bombus terrestris males
PLOS ONE, 2013Co-Authors: Jana Brabcová, Heiko Vogel, Irena Valterová, Zuzana Demianová, Darina Prchalova, Alena Bucankova, Iva Pichova, Marie ZarevuckaAbstract:Background: In addition to their general role in the hydrolysis of storage lipids, bumblebee lipases can participate in the biosynthesis of fatty acids that serve as precursors of pheromones used for sexual communication. Results: We studied the temporal dynamics of lipolytic activity in crude extracts from the cephalic part of Bombus terrestris Labial Glands. Extracts from 3-day-old males displayed the highest lipolytic activity. The highest lipase gene expression level was observed in freshly emerged bumblebees, and both gene expression and lipase activity were lower in bumblebees older than 3 days. Lipase was purified from Labial Glands, further characterized and named as BT-1. The B. terrestris orthologue shares 88% sequence identity with B. impatiens lipase HA. The molecular weight of B. terrestris lipase BT-1 was approximately 30 kDa, the pH optimum was 8.3, and the temperature optimum was 50°C. Lipase BT-1 showed a notable preference for C8-C10 p-nitrophenyl esters, with the highest activity toward pnitrophenyl caprylate (C8). The Michaelis constant (Km) and maximum reaction rate (Vmax) for p-nitrophenyl laurate hydrolysis were Km = 0.0011 mM and Vmax = 0.15 U/mg. Conclusion: This is the first report describing neutral lipase from the Labial gland of B. terrestris. Our findings help increase understanding of its possible function in the Labial gland.
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comparison of age dependent quantitative changes in the male Labial gland secretion of bombus terrestris and bombus lucorum
Journal of Chemical Ecology, 2009Co-Authors: Petr Zacek, Vladimir Ptacek, Audrey Coppee, Jan Sobotnik, Blanka Kalinova, Oldrich Hovorka, Francois Verheggen, Irena ValterováAbstract:Age-related changes of antennal-active components of male Labial gland extracts were studied in two closely related bumblebee species, Bombus terrestris and B. lucorum. In B. terrestris, compounds eliciting electroantennogram (EAG) responses of virgin queens were ethyl dodecanoate, 2,3-dihydrofarnesal, 2,3-dihydrofarnesol, hexadecan-1-ol, octadeca-9,12,15-trien-1-ol, and geranylcitronellol. Compounds that elicited EAG responses from queens of B. lucorum were ethyl dodecanoate, ethyl tetradec-7-enoate, ethyl tetradec-9-enoate, ethyl hexadec-9-enoate, hexadecan-1-ol, hexadec-7-enal, octadeca-9,12-dien-1-ol, octadeca-9,12,15-trien-1-ol, and octadecan-1-ol. Quantities of these compounds in the Labial Glands changed significantly over the lifetime of the respective males of the two species. In both species, concentrations of the respective compounds reached their maximum within seven days after eclosion. Subsequently, a rapid decrease in the amount of EAG-active compounds occurred in B. terrestris, whereas in B. lucorum the amount of active compounds stayed approximately constant or decreased at a slow rate. Microscopy showed that in B. terrestris secretory cells of the Labial Glands undergo apoptosis from the fifth to the tenth day of life, whilst in B. lucorum Labial gland cells remain unchanged throughout the life of the males.
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Age-dependent changes in the chemistry of exocrine Glands of Bombus terrestris queens.
Journal of Chemical Ecology, 2008Co-Authors: Klára Urbanová, Vladimir Ptacek, Lucie Cahlíková, Oldřich Hovorka, Irena ValterováAbstract:Extracts of three different Glands (mandibular, Labial, and Dufour’s) of virgin Bombus terrestris queens at ten different ages (1–8, 12, and 18 days) were analyzed for chemical composition. One hundred and twenty-seven compounds were identified in the extracts. The mandibular and Labial Glands contained previously reported electroantennogram-active compounds (3-hydroxydecanoic acid, fatty acids of different chain lengths, their esters, and heptacosene). These compounds reached a maximum concentration in 3- to 7-d-old queens. Geranylcitronellol was found in both Labial and Dufour’s Glands. Its amount was inversely correlated to age of queens.
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reduced cephalic Labial Glands in the male bumblebees of the subgenus rhodobombus dalla torre hymenoptera apidae bombus latreille
Annales De La Societe Entomologique De France, 2007Co-Authors: Michaël Terzo, Irena Valterová, Patrice Coppens, Gerard Toubeau, Pierre RasmontAbstract:Until now, all males of bumblebees are known to attract conspecifi c females by marking places with a chemical signal secreted by their cephalic Labial gland. The specifi c combination of patrolling fl ight and scentmarking is of outmost importance to bumblebees as it is their main species specifi c recognition system. We report here the lack of that recognition system in species of the subgenus Rhodobombus by comparing the morphology and histology of the cephalic Labial Glands of Bombus (Rhodobombus) mesomelas with those of a well known species, B. (Bombus) terrestris (L.) The cephalic Labial Glands are much smaller in B. mesomelas than in other bumblebees species and most likely non-functional. This morphology is also observed in B. pomorum and B. brodmanni which also belong to the subgenus Rhodobombus. Our morphological observations are consistent with the chemical analyses of the secretions in B. mesomelas and B. pomorum which are very limited and of most unusual composition for a bumblebee. In addition, whereas other species are thought to use their barbae mandibularis to spread their secretion onto the substrate, these structures are absent in all Rhodobombus. All these observations would mean that the males of Rhodobombus do not attract females from far away by the use of their cephalic Labial gland secretions. Resume. Glandes Labiales cephaliques reduites chez les mâles de bourdons du sous-genre Rhodobombus Dalla Torre (Hymenoptera : Apidae : Bombus Latreille). Jusqu'a present, tous les mâles de bourdons sont connus pour attirer leurs femelles conspecifi ques a l'aide d'un marquage odorant secrete par les glandes Labiales cephaliques. Les particularites du vol nuptial et de la composition de ce marquage odorant forment une combinaison d'une extreme importance puisqu'elle constitue le principal systeme de reconnaissance specifi que chez les bourdons. Dans ce travail, nous rapportons l'absence de ce systeme de reconnaissance specifi que chez les especes du sous-genre Rhodobombus. En comparant l'ultrastructure et l'histologie des glandes Labiales cephaliques de Bombus (Rhodobombus) mesomelas avec celles bien connues d'une autre espece, B. (Bombus) terrestris (L.) Nous constatons que les glandes Labiales cephaliques de B. mesomelas sont extremement reduites et qu'elles sont tres probablement non fonctionnelles. Cette morphologie est egalement observee chez B. pomorum et B. brodmanni, deux autres especes du sous-genre Rhodobombus. Ces observations morphologiques corroborent les analyses chimiques des secretions de ces glandes chez B. mesomelas et B. pomorum, lesquelles sont tres reduites et de composition tres inhabituelle pour des bourdons. De plus, alors que les autres especes de bourdons utilisent leurs barbae mandibularis pour deposer leurs secretions sur les substrats, ces organes sont absents chez tous les Rhodobombus. Tout ceci impliquerait que les mâles de Rhodobombus ne se servent pas de leurs glandes Labiales cephaliques pour attirer les femelles a distance.
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Atypical Secretions of the Male Cephalic Labial Glands in Bumblebees: The Case of Bombus (Rhodobombus) mesomelas Gerstaecker (Hymenoptera, Apidae)
Chemistry & biodiversity, 2007Co-Authors: Michaël Terzo, Irena Valterová, Pierre RasmontAbstract:In bumblebees, the male secretion of the cephalic Labial gland is species-specific. It is highly involved in the nuptial behavior, acting as a sexual attracting pheromone. Therefore, it is also used to accurately identify the species. In contrast to this common scheme, the secretions of Bombus mesomelas are found to be strongly reduced and do not include the most volatile compounds that are present in the secretions of all the other studied bumblebee species. These secretions correspond to cuticular hydrocarbons that can be found in all bumblebee species. This was also the case for another bumblebee species from the same Rhodobombus subgenus: Bombus pomorum. This atypical composition of the male cephalic Labial gland secretions seems to indicate that, at least for these two species of Rhodobombus, these secretions are not used to attract virgin females from a long distance, as it is the case for all the other bumblebee species studied.
