The Experts below are selected from a list of 138 Experts worldwide ranked by ideXlab platform
Franco Giorgi - One of the best experts on this subject based on the ideXlab platform.
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yolk uptake through the follicle epithelium in the ovary of the stick insect Carausius morosus
Arthropod Structure & Development, 2005Co-Authors: Anna Maria Fausto, Antonella Cecchettini, G Gambellini, Massimo Mazzini, Franco GiorgiAbstract:Abstract The ovarian follicular epithelium in insects is a polarized tissue sustaining vitellogenin uptake in growing oocytes. We studied this tissue in the stick insect Carausius morosus to establish how yolk polypeptides reach the oocyte. By confocal fluorescence analysis, follicle cells were shown to be polarized through differential distribution of cytoskeleton elements along opposite cell poles. Actin filaments were shown to prevail along the apical pole, whereas microtubules are much more numerous along the basal pole. Different labelling patterns were obtained when the follicular epithelium was tested with antibodies against either a vitellogenin polypeptide (mAb 1B12) or another 85 kDa yolk protein (mAb 4G12) on cryostat sections. Follicle cells maintain such a polarization even when isolated or cultured in vitro. Under these latter conditions only the labelling pattern due to the 85 kDa protein was retained in the follicle cell cytoplasm, suggesting that two different pathways are available in the follicular epithelium of stick insects: an intercellular pathway for the vitellogenin polypeptides and an intracellular one for the 85 kDa protein.
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vitellogenin is glycosylated in the fat body of the stick insect Carausius morosus and not further modified upon transfer to the ovarian follicle
Micron, 1998Co-Authors: Franco Giorgi, Massimo Masetti, Antonella Cecchettini, Alessandra Falleni, Vittorio GremigniAbstract:Abstract Synthesis and secretion of vitellogenin (Vg) polypeptides were studied in egg-laying females of the stick insect Carausius morosus following in vivo exposure to [ 35 S]-methionine and acetyl- N -[ 3 H]-glucosamine. The specificity of radioisotope incorporation was assessed by in vitro inhibition with tunicamycin and carbohydrate extraction with endo-glycosidase H. Vg polypeptides change in molecular weight during synthesis in the fat body and are not further modified upon transfer to the haemolymph or to the oocyte, suggesting that they are already fully glycosylated prior to secretion. Radioactivity in the fat body was initially distributed over cisternae of the rough endoplasmic reticulum and gradually transferred to the Golgi apparatus. Within an hour of exposure, electron-dense granules budding from the trans -Golgi network became preferentially labeled. Radioactivity in the ovarian follicle was restricted to the yolk granules of the cortical ooplasm and to the amorphous material lying within the intercellular channels of the follicular epithelium. This amorphous material was also shown to react positively when tested with a monoclonal antibody raised specifically against a Vg polypeptide.
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cells released in vitro from the embryonic yolk sac of the stick insect Carausius morosus br phasmatodea heteronemiidae may include embryonic hemocytes
International Journal of Insect Morphology & Embryology, 1998Co-Authors: Teresa M Locci, Massimo Masetti, Antonella Cecchettini, Franco GiorgiAbstract:The embryonic yolk sac and the adult dorsal vessel of the stick insect Carausius morosus (Br.) (Phasmatodea : Heteronemiidae) were shown to release a number of cells that appear morphologically similar to circulating adult hemocytes. Like adult hemocytes, these cells reacted positively when tested for both phenoloxidase activity and a monoclonal antibody specifically raised against a vitellin polypeptide. Based on this evidence, it is suggested that yolk sac-released cells behave as potential embryonic hemocytes. A model is thus proposed whereby the yolk sac might host a number of hemopoietic stem cells on their way to the dorsal vessel, and in so doing, it may temporally act as an embryonic hemopoietic organ.
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mono and polyclonal antibodies as probes to study vitellin processing in embryos of the stick insect Carausius morosus
Comparative Biochemistry and Physiology B, 1998Co-Authors: Massimo Masetti, Antonella Cecchettini, Franco GiorgiAbstract:Abstract During embryonic development, insect vitellins (Vt) are degraded by limited proteolysis to yield a number of lower-molecular weight polypeptides. The aim of the present study was to identify these polypeptides in the embryo and to verify how they relate to Vt polypeptides deposited in the oocyte during vitellogenesis. To this end a panel of poly- and monoclonal antibodies (Pab, Mab) was raised against Vt polypeptides and employed by immunoelectrophoresis and immunoblotting on embryos belonging to different developmental stages. Through this approach three major staining patterns were observed. First, Mab 4 reacts with both polypeptides B 1 and E 20 , suggesting that polypeptide B 1 is gradually trimmed to yield polypeptide E 20 in late embryos. Second, Mab 12 is specific for polypeptide A 3 which is retained unchanged throughout embryogenesis. Third, Pab anti-A 2 and Mab 13 show that polypeptide A 2 is processed to yield polypeptide E 9 through limited proteolysis. In conclusion, the staining patterns reported in this study show that Vt polypeptides in developing embryos of the stick insect Carausius morosus undergo at least two major processing events concerning polypeptides B 1 and A 2 .
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the yolk sac in late embryonic development of the stick insect Carausius morosus br
Tissue & Cell, 1997Co-Authors: Anna Maria Fausto, Antonella Cecchettini, Massimo Mazzini, Franco GiorgiAbstract:Abstract Differentiation of the yolk sac was examined ultrastructurally and cytochemically in late embryonic development of the stick insect Carausius morosus . During migration along the yolk sac, endodermal cells form a discontinuous cell epithelium, leaving wide intercellular channels between neighbouring cell clusters. Within the same cell cluster, cells are all joined by septate junctions. In the proximity of the proctodeum region, intercellular channels are filled with numerous cell debris which are shown to derive from vitellophages undergoing cell lysis. Yolk sacs resolved by gel electrophoresis are shown to release a number of vitellin polypeptides into the culture medium. These are equivalent in molecular weight to those present in the vitellophage yolk granules This observation is consistent with the evidence that the basement lamina may act as a course physical filter, retaining particles larger than colloidal thorium dioxide and allowing free percolation of peroxidase. Differentiating endodermal cells form a microvillar striated border along the apical plasma membrane. A number of vesicular criptae were frequently seen in these differentiating endodermal cells. Electron dense granules released by endodermal cells are suggested to play a role in vitellophage lysis and vitellin release from the enclosed yolk granules.
Antonella Cecchettini - One of the best experts on this subject based on the ideXlab platform.
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yolk uptake through the follicle epithelium in the ovary of the stick insect Carausius morosus
Arthropod Structure & Development, 2005Co-Authors: Anna Maria Fausto, Antonella Cecchettini, G Gambellini, Massimo Mazzini, Franco GiorgiAbstract:Abstract The ovarian follicular epithelium in insects is a polarized tissue sustaining vitellogenin uptake in growing oocytes. We studied this tissue in the stick insect Carausius morosus to establish how yolk polypeptides reach the oocyte. By confocal fluorescence analysis, follicle cells were shown to be polarized through differential distribution of cytoskeleton elements along opposite cell poles. Actin filaments were shown to prevail along the apical pole, whereas microtubules are much more numerous along the basal pole. Different labelling patterns were obtained when the follicular epithelium was tested with antibodies against either a vitellogenin polypeptide (mAb 1B12) or another 85 kDa yolk protein (mAb 4G12) on cryostat sections. Follicle cells maintain such a polarization even when isolated or cultured in vitro. Under these latter conditions only the labelling pattern due to the 85 kDa protein was retained in the follicle cell cytoplasm, suggesting that two different pathways are available in the follicular epithelium of stick insects: an intercellular pathway for the vitellogenin polypeptides and an intracellular one for the 85 kDa protein.
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vitellogenin is glycosylated in the fat body of the stick insect Carausius morosus and not further modified upon transfer to the ovarian follicle
Micron, 1998Co-Authors: Franco Giorgi, Massimo Masetti, Antonella Cecchettini, Alessandra Falleni, Vittorio GremigniAbstract:Abstract Synthesis and secretion of vitellogenin (Vg) polypeptides were studied in egg-laying females of the stick insect Carausius morosus following in vivo exposure to [ 35 S]-methionine and acetyl- N -[ 3 H]-glucosamine. The specificity of radioisotope incorporation was assessed by in vitro inhibition with tunicamycin and carbohydrate extraction with endo-glycosidase H. Vg polypeptides change in molecular weight during synthesis in the fat body and are not further modified upon transfer to the haemolymph or to the oocyte, suggesting that they are already fully glycosylated prior to secretion. Radioactivity in the fat body was initially distributed over cisternae of the rough endoplasmic reticulum and gradually transferred to the Golgi apparatus. Within an hour of exposure, electron-dense granules budding from the trans -Golgi network became preferentially labeled. Radioactivity in the ovarian follicle was restricted to the yolk granules of the cortical ooplasm and to the amorphous material lying within the intercellular channels of the follicular epithelium. This amorphous material was also shown to react positively when tested with a monoclonal antibody raised specifically against a Vg polypeptide.
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cells released in vitro from the embryonic yolk sac of the stick insect Carausius morosus br phasmatodea heteronemiidae may include embryonic hemocytes
International Journal of Insect Morphology & Embryology, 1998Co-Authors: Teresa M Locci, Massimo Masetti, Antonella Cecchettini, Franco GiorgiAbstract:The embryonic yolk sac and the adult dorsal vessel of the stick insect Carausius morosus (Br.) (Phasmatodea : Heteronemiidae) were shown to release a number of cells that appear morphologically similar to circulating adult hemocytes. Like adult hemocytes, these cells reacted positively when tested for both phenoloxidase activity and a monoclonal antibody specifically raised against a vitellin polypeptide. Based on this evidence, it is suggested that yolk sac-released cells behave as potential embryonic hemocytes. A model is thus proposed whereby the yolk sac might host a number of hemopoietic stem cells on their way to the dorsal vessel, and in so doing, it may temporally act as an embryonic hemopoietic organ.
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mono and polyclonal antibodies as probes to study vitellin processing in embryos of the stick insect Carausius morosus
Comparative Biochemistry and Physiology B, 1998Co-Authors: Massimo Masetti, Antonella Cecchettini, Franco GiorgiAbstract:Abstract During embryonic development, insect vitellins (Vt) are degraded by limited proteolysis to yield a number of lower-molecular weight polypeptides. The aim of the present study was to identify these polypeptides in the embryo and to verify how they relate to Vt polypeptides deposited in the oocyte during vitellogenesis. To this end a panel of poly- and monoclonal antibodies (Pab, Mab) was raised against Vt polypeptides and employed by immunoelectrophoresis and immunoblotting on embryos belonging to different developmental stages. Through this approach three major staining patterns were observed. First, Mab 4 reacts with both polypeptides B 1 and E 20 , suggesting that polypeptide B 1 is gradually trimmed to yield polypeptide E 20 in late embryos. Second, Mab 12 is specific for polypeptide A 3 which is retained unchanged throughout embryogenesis. Third, Pab anti-A 2 and Mab 13 show that polypeptide A 2 is processed to yield polypeptide E 9 through limited proteolysis. In conclusion, the staining patterns reported in this study show that Vt polypeptides in developing embryos of the stick insect Carausius morosus undergo at least two major processing events concerning polypeptides B 1 and A 2 .
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the yolk sac in late embryonic development of the stick insect Carausius morosus br
Tissue & Cell, 1997Co-Authors: Anna Maria Fausto, Antonella Cecchettini, Massimo Mazzini, Franco GiorgiAbstract:Abstract Differentiation of the yolk sac was examined ultrastructurally and cytochemically in late embryonic development of the stick insect Carausius morosus . During migration along the yolk sac, endodermal cells form a discontinuous cell epithelium, leaving wide intercellular channels between neighbouring cell clusters. Within the same cell cluster, cells are all joined by septate junctions. In the proximity of the proctodeum region, intercellular channels are filled with numerous cell debris which are shown to derive from vitellophages undergoing cell lysis. Yolk sacs resolved by gel electrophoresis are shown to release a number of vitellin polypeptides into the culture medium. These are equivalent in molecular weight to those present in the vitellophage yolk granules This observation is consistent with the evidence that the basement lamina may act as a course physical filter, retaining particles larger than colloidal thorium dioxide and allowing free percolation of peroxidase. Differentiating endodermal cells form a microvillar striated border along the apical plasma membrane. A number of vesicular criptae were frequently seen in these differentiating endodermal cells. Electron dense granules released by endodermal cells are suggested to play a role in vitellophage lysis and vitellin release from the enclosed yolk granules.
Massimo Masetti - One of the best experts on this subject based on the ideXlab platform.
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vitellogenin is glycosylated in the fat body of the stick insect Carausius morosus and not further modified upon transfer to the ovarian follicle
Micron, 1998Co-Authors: Franco Giorgi, Massimo Masetti, Antonella Cecchettini, Alessandra Falleni, Vittorio GremigniAbstract:Abstract Synthesis and secretion of vitellogenin (Vg) polypeptides were studied in egg-laying females of the stick insect Carausius morosus following in vivo exposure to [ 35 S]-methionine and acetyl- N -[ 3 H]-glucosamine. The specificity of radioisotope incorporation was assessed by in vitro inhibition with tunicamycin and carbohydrate extraction with endo-glycosidase H. Vg polypeptides change in molecular weight during synthesis in the fat body and are not further modified upon transfer to the haemolymph or to the oocyte, suggesting that they are already fully glycosylated prior to secretion. Radioactivity in the fat body was initially distributed over cisternae of the rough endoplasmic reticulum and gradually transferred to the Golgi apparatus. Within an hour of exposure, electron-dense granules budding from the trans -Golgi network became preferentially labeled. Radioactivity in the ovarian follicle was restricted to the yolk granules of the cortical ooplasm and to the amorphous material lying within the intercellular channels of the follicular epithelium. This amorphous material was also shown to react positively when tested with a monoclonal antibody raised specifically against a Vg polypeptide.
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cells released in vitro from the embryonic yolk sac of the stick insect Carausius morosus br phasmatodea heteronemiidae may include embryonic hemocytes
International Journal of Insect Morphology & Embryology, 1998Co-Authors: Teresa M Locci, Massimo Masetti, Antonella Cecchettini, Franco GiorgiAbstract:The embryonic yolk sac and the adult dorsal vessel of the stick insect Carausius morosus (Br.) (Phasmatodea : Heteronemiidae) were shown to release a number of cells that appear morphologically similar to circulating adult hemocytes. Like adult hemocytes, these cells reacted positively when tested for both phenoloxidase activity and a monoclonal antibody specifically raised against a vitellin polypeptide. Based on this evidence, it is suggested that yolk sac-released cells behave as potential embryonic hemocytes. A model is thus proposed whereby the yolk sac might host a number of hemopoietic stem cells on their way to the dorsal vessel, and in so doing, it may temporally act as an embryonic hemopoietic organ.
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mono and polyclonal antibodies as probes to study vitellin processing in embryos of the stick insect Carausius morosus
Comparative Biochemistry and Physiology B, 1998Co-Authors: Massimo Masetti, Antonella Cecchettini, Franco GiorgiAbstract:Abstract During embryonic development, insect vitellins (Vt) are degraded by limited proteolysis to yield a number of lower-molecular weight polypeptides. The aim of the present study was to identify these polypeptides in the embryo and to verify how they relate to Vt polypeptides deposited in the oocyte during vitellogenesis. To this end a panel of poly- and monoclonal antibodies (Pab, Mab) was raised against Vt polypeptides and employed by immunoelectrophoresis and immunoblotting on embryos belonging to different developmental stages. Through this approach three major staining patterns were observed. First, Mab 4 reacts with both polypeptides B 1 and E 20 , suggesting that polypeptide B 1 is gradually trimmed to yield polypeptide E 20 in late embryos. Second, Mab 12 is specific for polypeptide A 3 which is retained unchanged throughout embryogenesis. Third, Pab anti-A 2 and Mab 13 show that polypeptide A 2 is processed to yield polypeptide E 9 through limited proteolysis. In conclusion, the staining patterns reported in this study show that Vt polypeptides in developing embryos of the stick insect Carausius morosus undergo at least two major processing events concerning polypeptides B 1 and A 2 .
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vitellogenesis in the allatectomized stick insect Carausius morosus br phasmatodea lonchodinae
Comparative Biochemistry and Physiology B, 1995Co-Authors: James T Bradley, Massimo Masetti, Antonella Cecchettini, Franco GiorgiAbstract:Abstract Effects of allatectomy on vitellogenesis in adult Carausius morosus Br. were examined using rocket immunoelectrophoresis, polyacrylamide gel electrophoresis, fluorographic identification and quantitation by liquid scintillation of in vivo35S-methionine-labeled proteins, and light microscope autoradiography. In normal adults and in adults allatectomized as last instar nymphs, Coomassie Blue-stained vitellogenin (Vg) was first detectable in the hemolymph between 3 and 5 days after adult emergence. Allatectomy of 11–18-day-old adults produced no detectable effects on subsequent Vg synthesis, secretion or uptake, but ovarian follicles in adults that had been allatectomized as nymphs were less efficient at taking up Vg than were those in sham-operated animals. Compared to sham-operated controls, adults allatectomized as nymphs displayed an increased rate of accumulation of newly synthesized Vg in the hemolymph, a decreased rate of accumulation of vitellin in terminal follicles, a decrease in the size of yolk spheres containing newly synthesized vitellogenic protein in the peripheral ooplasm, and alterations in the size distribution of terminal follicles. Thus, post-induction vitellogenesis and primary induction of Vg synthesis in C. morosus do not require active corpora allata (CA), but a normal rate of Vg uptake may be JH-facilitated.
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a fat body derived protein is selectively sulfated during transit to ovarian follicles in the stick insect Carausius morosus
Developmental Biology, 1995Co-Authors: Franco Giorgi, Massimo Masetti, Antonella Cecchettini, Maria Teresa Fernanda Locci, Jt BradleyAbstract:A monoclonal antibody raised against ovarian follicles of the stick insect Carausius morosus reacted with two related polypeptides of 157 and 85 kDa in both the ovary and the hemolymph. In vitro cultured fat body proved capable of releasing the 157-kDa polypeptide into the culture medium and processing it to the lower-molecular-weight polypeptide of 85 kDa. This was further demonstrated by in vitro exposure to [35S]methionine. Under the same culturing conditions, ovarian follicles proved incapable of synthesizing and/or secreting the 85-kDa polypeptide. However, in vivo [35S]methionine-labeled ovarian follicles released both polypeptides when cultured in vitro for up to 24 hr. Vitellogenin polypeptides were labeled in vivo following exposure to [3H]glucosamine, while 157- and 85-kDa polypeptides were labeled only in ovarian follicles exposed in vivo to sodium [35S]sulfate. Under in vitro conditions, the 157-kDa polypeptide could be labeled with sodium [35S]sulfate only if ovarian follicles were cocultured with fat body. No sulfation occurred in fat body or ovarian follicles cultured separately. These experiments suggest that the 157-kDa polypeptide is a fat body-derived polypeptide that is sulfated upon transfer to the ovarian follicle.
Ian Orchard - One of the best experts on this subject based on the ideXlab platform.
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localization and neurohemal release of fmrfamide related peptides in the stick insect Carausius morosus
Peptides, 1997Co-Authors: Sharon Miksys, Angela B Lange, Ian Orchard, Victor WongAbstract:Abstract Miksys, S., A.B. Lange, I. Orchard and V. Wong. Localization and neurohemal release of FMRFamide-related peptides in the stick insect Carausius morosus. Peptides 18(1) 27–40, 1997.—FMRFamide-like immunoreactivity was localized immunohistochemically in the central and stomatogastric nervous systems, visceral tissues, and the neurohemal corpora cardiaca, transverse, and segmental nerves. Each of these neurohemal areas contains one morphologically distinct type of immunoreactive neurosecretory granule. The hemolymph level of FMRFamide-like peptides, quantified by RIA, is higher in animals sampled 2 h into the dark cycle, relative to those sampled at mid-light cycle or 9 h into the dark cycle. High potassium depolarization evokes the calcium-dependent release of FMRFamide-like peptides from neurohemal areas in vitro and HPLC fractionation of hemolymph, corpora cardiaca, and their bathing medium suggests that these organs contribute a single peptide to the FMRFamide-related peptides circulating in the hemolymph of active animals.
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immunohistochemical localization of tyrosine hydroxylase in the ventral nerve cord of the stick insect Carausius morosus including neurons innervating the salivary glands
Cell and Tissue Research, 1996Co-Authors: Ian OrchardAbstract:The distribution of tyrosine hydroxylase-like immunoreactive neurons is mapped in the ventral nerve cord of the stick insect, Carausius morosus. This study also examines the tyrosine hydroxylase- and serotonin-like immunoreactive elements in the salivary glands of Carausius morosus. Tyrosine hydroxylase is the first and rate-limiting enzyme in the pathway for the production of catecholamines; therefore, tyrosine hydroxylase-like immunoreactive neurons are likely to contain catecholamines. Approximately 225 tyrosine hydroxylase-like immunoreactive neurons are present in the ventral nerve cord. The majority of these neurons appear to be interneurons. The suboesophageal ganglion contains the only unpaired neuron and the only pair of peripherally projecting tyrosine hydroxylase-like immunoreactive neurons in the ventral nerve cord. The peripherally projecting neurons project to the salivary glands via the salivary nerve. Each neuron in this pair is termed the salivary neuron 1. The remaining tyrosine hydroxylase-like immunoreactive neurons in the ventral nerve cord are interneurons and exhibit a characteristic distribution within the thoracic and the abdominal ganglia. Serotoninlike immunoreactivity is also present in the salivary glands. Positive staining of the suboesophageal ganglion for serotoninlike immunoreactivity indicates the presence of several neuron pairs including a large pair along the ventral posterior midline that project to the salivary glands via the salivary nerve. Each neuron in this pair is termed the salivary neuron 2. Backfilling of the salivary nerve with cobalt chloride reveals the presence of only two neurons within the suboesophageal ganglion that project to the salivary glands; these neurons are the salivary neurons 1 and 2. Reverse-phase high-performance liquid chromatography coupled with electrochemical detection of ventral nerve cord and salivary gland homogenates confirms the presence of dopamine and serotonin.
Steven F Perry - One of the best experts on this subject based on the ideXlab platform.
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stereological determination of tracheal volume and diffusing capacity of the tracheal walls in the stick insect Carausius morosus phasmatodea lonchodidae
Physiological and Biochemical Zoology, 1999Co-Authors: Anke Schmitz, Steven F PerryAbstract:Abstract First instars of Carausius morosus provide a good model for morphometric evaluation of the diffusing capacity between the tracheal system and hemolymph: air sacs are lacking, tracheoles do not penetrate the organs and muscles, and entire animals can be evaluated electron microscopically without subsampling. The tracheal volume makes up 1.3% of the volume of the whole insect excluding appendages. We calculated the lateral diffusing capacity for oxygen and carbon dioxide for five classes of tracheae according to their diameters, from 0.2 μm to 35 μm. The harmonic mean thickness of the tracheal epithelium is lowest in smallest tracheae and increases with increasing tracheal diameter. Although the smallest tracheae make up 70% (O2) and 60% (CO2) of the total diffusing capacity, the proximal four classes may also be significant in diffusion of oxygen and particularly of carbon dioxide. The suppression of the development of respiratory pigments in the evolution of terrestrial insects may have increased...