The Experts below are selected from a list of 210 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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Vitellin cleavage products are proteolytically degraded by ubiquitination in stick insect embryos
Micron (Oxford England : 1993), 2003Co-Authors: Antonella Cecchettini, Massimo Masetti, Massimo Mazzini, Maria Teresa Fernanda Locci, Anna Maria Fausto, Gabriella Gambellini, Franco GiorgiAbstract:Abstract Vitellin polypeptides are proteolytically processed in ovarian follicles and embryos of the stick insect Carausius morosus. Data show that Vitellin polypeptide A3 of 54 kDa is processed to yield polypeptide A3∗ of about 48 kDa upon completion of ovarian development, whereas Vitellin polypeptide A2 of 90 kDa yields polypeptide E9 during embryonic development. As Vitellin polypeptides are processed, polypeptides A3∗ and E9 are transferred from the yolk granules to the cytosolic space of the vitellophages and start to express a ubiquitin reactivity. At the confocal microscope, anti-ubiquitin antibodies label specifically numerous small yolk granules and the cytosolic space of vitellophages. During embryonic development, ubiquitin carrying granules undergo acidification in much the same way as larger yolk granules. However, only these latter organelles are capable of converting a latent cysteine pro-protease into an active yolk protease upon acidification of their luminal space. These data are interpreted as indicating that ubiquitin-like polypeptides are restricted to small granules throughout ovarian and embryonic development, and that Vitellin cleavage products are ubiquitinated following acidification of large yolk granules and transfer to the cytosolic space of the vitellophages.
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Vitellin polypeptide pathways in late insect yolk sacs.
Arthropod structure & development, 2002Co-Authors: Antonella Cecchettini, Massimo Masetti, Vittoria Scarcelli, Maria Teresa Fernanda Locci, Franco GiorgiAbstract:A panel of monoclonal antibodies was raised against late yolk sacs of the stick insect Carausius morosus and tested by immunoblotting to establish the extent Vitellin polypeptides are processed proteolytically during embryonic development. Cryosections of late yolk sacs were also examined by confocal laser microscopy to determine how Vitellin cleavage products become spatially distributed amongst yolk granules during the same developmental period. Distinct labelling patterns were obtained on yolk granules depending on: (1) the nature of the proteolytic processing; (2) the origin of Vitellin cleavage products; and ultimately (3) their molecular sizes. Monoclonal antibodies raised against Vitellin cleavage products resulting from proteolytic processing appeared to label: (1) the entire volume of many yolk granules; (2) their limiting membrane; or (3) a number of small vesicles interposed between larger yolk granules. On the other hand, monoclonal antibodies against Vitellin cleavage products that remain invariant throughout development appeared to label either the serosa membrane or the cytosolic space comprised between adjacent yolk granules. Data are interpreted as indicating that Vitellin cleavage products may leak out from the yolk granules, gain access to the cytosolic space of the vitellophages and eventually percolate through the serosa membrane enclosing the yolk sac.
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oocyte growth follicle cell differentiation and Vitellin processing in the stick insect carausius morosus br phasmatodea
International Journal of Insect Morphology & Embryology, 1993Co-Authors: Franco Giorgi, Paolo Lucchesi, Antonella Cecchettini, Massimo MazziniAbstract:Abstract Ovarian growth in stick insects (Phasmatodea) was examined ultrastructurally and cytochemically with a view to studying: (1) the kinetics of oocyte growth and the staging characteristics of ovarian follicles undergoing vitellogenesis; (2) the endocytic capability of the growing oocyte, including the post-endocytic fate of the Vitellins sequestered by the oocyte during vitellogenesis; (3) the differentiation of the follicular epithelium in relation to the appearance of intercellular spaces and the extracellular release of a follicle cell product. These structural observations were interpreted in relation to the nature and kinetics of the Vitellin processing in follicles undergoing vitellogenesis.
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postendocytic Vitellin processing in ovarian follicles of the stick insect carausius morosus br
Archives of Insect Biochemistry and Physiology, 1993Co-Authors: Franco Giorgi, Vincenzo Ignacchiti, Massimo Masetti, Antonella Cecchettini, James T. BradleyAbstract:Newly laid eggs of the stick insect Carausius morosus contain two native Vitellins (Vit A and Vit B). Under denaturing conditions, these Vitellins resolved into 3 (A1, A2, and A3) and 2 (B1 and B2) polypeptides. All of these polypeptides had counterparts in the female hemolymph from which they were shown to be derived by in vivo labelling. During ovarian development, the 2 Vitellins changed both in charge and polypeptide composition. In EV and LV follicles, Vit A resolved into 4 distinct Vitellin polypeptides (A0, A1, A2 and A3). Using a panel of monoclonal antibodies, polypeptide A0 proved to be immunologically related to polypeptide A2. In follicles about to begin choriongenesis, polypeptide A3 was gradually replaced by a lower Mr polypeptide. Over the same time period, polypeptide B1 changed in charge, but not in Mr. To confirm the existence of a polypeptide processing in C. morosus, ovarian follicles of different developmental stages were exposed in vivo to [35S]-methionine from 6 to 72 h. Data showed that A0 and B1 were the polypeptides most heavily labelled after short time exposures to the radioisotope. Polypeptides B2 and A3 were also labelled to some extent. With progressively longer exposures, polypeptides A1 and A2 also became labelled. In vivo exposure to [3H]-GlcNAc caused all Vitellin polypeptides to become heavily labelled. Autoradiographic analysis of ovarian follicles labelled this way showed that, during development, radioactivity was gradually transferred from newly formed yolk spheres in the cortical ooplasm to the central ooplasm. Data were interpreted as suggesting a causal relationship between polypeptide processing and progressive yolk sphere fusion to yield the central ooplasm. © 1993 Wiley-Liss, Inc.
Antonella Cecchettini - One of the best experts on this subject based on the ideXlab platform.
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Vitellin cleavage products are proteolytically degraded by ubiquitination in stick insect embryos
Micron (Oxford England : 1993), 2003Co-Authors: Antonella Cecchettini, Massimo Masetti, Massimo Mazzini, Maria Teresa Fernanda Locci, Anna Maria Fausto, Gabriella Gambellini, Franco GiorgiAbstract:Abstract Vitellin polypeptides are proteolytically processed in ovarian follicles and embryos of the stick insect Carausius morosus. Data show that Vitellin polypeptide A3 of 54 kDa is processed to yield polypeptide A3∗ of about 48 kDa upon completion of ovarian development, whereas Vitellin polypeptide A2 of 90 kDa yields polypeptide E9 during embryonic development. As Vitellin polypeptides are processed, polypeptides A3∗ and E9 are transferred from the yolk granules to the cytosolic space of the vitellophages and start to express a ubiquitin reactivity. At the confocal microscope, anti-ubiquitin antibodies label specifically numerous small yolk granules and the cytosolic space of vitellophages. During embryonic development, ubiquitin carrying granules undergo acidification in much the same way as larger yolk granules. However, only these latter organelles are capable of converting a latent cysteine pro-protease into an active yolk protease upon acidification of their luminal space. These data are interpreted as indicating that ubiquitin-like polypeptides are restricted to small granules throughout ovarian and embryonic development, and that Vitellin cleavage products are ubiquitinated following acidification of large yolk granules and transfer to the cytosolic space of the vitellophages.
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Vitellin polypeptide pathways in late insect yolk sacs.
Arthropod structure & development, 2002Co-Authors: Antonella Cecchettini, Massimo Masetti, Vittoria Scarcelli, Maria Teresa Fernanda Locci, Franco GiorgiAbstract:A panel of monoclonal antibodies was raised against late yolk sacs of the stick insect Carausius morosus and tested by immunoblotting to establish the extent Vitellin polypeptides are processed proteolytically during embryonic development. Cryosections of late yolk sacs were also examined by confocal laser microscopy to determine how Vitellin cleavage products become spatially distributed amongst yolk granules during the same developmental period. Distinct labelling patterns were obtained on yolk granules depending on: (1) the nature of the proteolytic processing; (2) the origin of Vitellin cleavage products; and ultimately (3) their molecular sizes. Monoclonal antibodies raised against Vitellin cleavage products resulting from proteolytic processing appeared to label: (1) the entire volume of many yolk granules; (2) their limiting membrane; or (3) a number of small vesicles interposed between larger yolk granules. On the other hand, monoclonal antibodies against Vitellin cleavage products that remain invariant throughout development appeared to label either the serosa membrane or the cytosolic space comprised between adjacent yolk granules. Data are interpreted as indicating that Vitellin cleavage products may leak out from the yolk granules, gain access to the cytosolic space of the vitellophages and eventually percolate through the serosa membrane enclosing the yolk sac.
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oocyte growth follicle cell differentiation and Vitellin processing in the stick insect carausius morosus br phasmatodea
International Journal of Insect Morphology & Embryology, 1993Co-Authors: Franco Giorgi, Paolo Lucchesi, Antonella Cecchettini, Massimo MazziniAbstract:Abstract Ovarian growth in stick insects (Phasmatodea) was examined ultrastructurally and cytochemically with a view to studying: (1) the kinetics of oocyte growth and the staging characteristics of ovarian follicles undergoing vitellogenesis; (2) the endocytic capability of the growing oocyte, including the post-endocytic fate of the Vitellins sequestered by the oocyte during vitellogenesis; (3) the differentiation of the follicular epithelium in relation to the appearance of intercellular spaces and the extracellular release of a follicle cell product. These structural observations were interpreted in relation to the nature and kinetics of the Vitellin processing in follicles undergoing vitellogenesis.
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postendocytic Vitellin processing in ovarian follicles of the stick insect carausius morosus br
Archives of Insect Biochemistry and Physiology, 1993Co-Authors: Franco Giorgi, Vincenzo Ignacchiti, Massimo Masetti, Antonella Cecchettini, James T. BradleyAbstract:Newly laid eggs of the stick insect Carausius morosus contain two native Vitellins (Vit A and Vit B). Under denaturing conditions, these Vitellins resolved into 3 (A1, A2, and A3) and 2 (B1 and B2) polypeptides. All of these polypeptides had counterparts in the female hemolymph from which they were shown to be derived by in vivo labelling. During ovarian development, the 2 Vitellins changed both in charge and polypeptide composition. In EV and LV follicles, Vit A resolved into 4 distinct Vitellin polypeptides (A0, A1, A2 and A3). Using a panel of monoclonal antibodies, polypeptide A0 proved to be immunologically related to polypeptide A2. In follicles about to begin choriongenesis, polypeptide A3 was gradually replaced by a lower Mr polypeptide. Over the same time period, polypeptide B1 changed in charge, but not in Mr. To confirm the existence of a polypeptide processing in C. morosus, ovarian follicles of different developmental stages were exposed in vivo to [35S]-methionine from 6 to 72 h. Data showed that A0 and B1 were the polypeptides most heavily labelled after short time exposures to the radioisotope. Polypeptides B2 and A3 were also labelled to some extent. With progressively longer exposures, polypeptides A1 and A2 also became labelled. In vivo exposure to [3H]-GlcNAc caused all Vitellin polypeptides to become heavily labelled. Autoradiographic analysis of ovarian follicles labelled this way showed that, during development, radioactivity was gradually transferred from newly formed yolk spheres in the cortical ooplasm to the central ooplasm. Data were interpreted as suggesting a causal relationship between polypeptide processing and progressive yolk sphere fusion to yield the central ooplasm. © 1993 Wiley-Liss, Inc.
Ching-fong Chang - One of the best experts on this subject based on the ideXlab platform.
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Isolation and Characterization of the Female-Specific Protein (Vitellogenin) in Mature Female Hemolymph of the Freshwater Prawn,Macrobrachium rosenbergii:Comparison with Ovarian Vitellin☆
General and comparative endocrinology, 1997Co-Authors: Fang-yi Lee, Tung-wei Shih, Ching-fong ChangAbstract:Purification and characterization of the female-specific protein (vitellogenin) from the hemolymph of mature female prawn, Macrobrachium rosenbergii, were the objectives of this study. The comparison of biochemical characteristics between vitellogenin and ovarian Vitellin was also conducted. Hemolymph vitellogenin was purified with DEAE, hydroxylapatite, and another DEAE chromatographic column. The specific protein (vitellogenin) was shown in the fractions of chromatographic columns on the basis of ELISA, Western blotting, and immunoprecipitation. A purified vitellogenin was obtained with an apparent molecular weight of 700 kDa as determined by PAGE. The purified vitellogenin was considered as a lipoglycoprotein on the basis of staining data. Three subunits (170, 100, and 89 kDa) in purified vitellogenin and two subunits (100 and 89 kDa) in Vitellin were detected with SDS-PAGE. Nondisulfide bonds were found in the binding of polypeptide subunits. Only the 89-kDa subunit was a glycopolypeptide in both vitellogenin and Vitellin. The amino acid composition of vitellogenin differed from that of Vitellin in a few amino acids. Eight amino acid sequences from the N-terminal end of 89- and 100-kDa subunits were determined and they were identical between vitellogenin and Vitellin. Seven amino acid sequence from the N-terminal end of the 170-kDa subunit were also identical to the 100-kDa subunit. Purified vitellogenin was more susceptible to precipitation in a solution with low ionic strength than Vitellin. This study suggests a close relationship between vitellogenin and Vitellin in M. rosenbergii in their biochemical characteristics.
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The Concentrations of Vitellogenin (Vitellin) and Protein in Hemolymph, Ovary and Hepatopancreas in Different Ovarian Stages of the Freshwater Prawn, Macrobrachium rosenbergii
Comparative biochemistry and physiology. Part A Physiology, 1997Co-Authors: Fang-yi Lee, Ching-fong ChangAbstract:Abstract The objectives were to measure the concentrations of vitellogenin (Vitellin) and protein in hemolymph, ovary, and hepatopancreas of the freshwater prawn, Macrobrachium rosenbergii, in different stages of ovarian development. The ovarian development of M. rosenbergii was classified into five developmental stages (Stages I–V). Vitellogenin concentrations increased in the hemolymph of prawns in the early stages of ovarian development (Stage I or II) and were maintained at high levels until Stage V. There was no close association between ovarian development and the concentrations of circulating vitellogenin. Concentrations of protein in hemolymph and hepatopancreas remained constant during various stages of ovarian development. The ovarian stages closely correlated with the gonadosomatic index, the concentrations of ovarian Vitellin and protein, respectively. Vitellogenin levels in hepatopancreas remained very low in different stages of the prawn although the highest levels were observed in Stage IV. No close association between hemolymph vitellogenin and ovarian Vitellin was observed. The increase of vitellogenin concentration in hemolymph occurred earlier than Vitellin content in ovary.
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Purification and characterization of Vitellin from the mature ovaries of prawn, Macrobrachium rosenbergh
Comparative Biochemistry and Physiology Part B: Comparative Biochemistry, 1993Co-Authors: Ching-fong Chang, Tung-wei Shih, Hsai-hsia HongAbstract:Abstract 1. 1. A purified Vitellin was isolated from the mature ovaries of the prawn (Macrobrachium rosenbergii) after the purification with gel filtration, DEAE-Sephacel, high-performance liquid chromatography (HPLC) and polyacrylamide gel electrophoresis (PAGE). 2. 2. Three Vitellins were detected in PAGE and HPLC and their respective retention times in HPLC were 30.7 min (Vn 1, molecular weight = 240 kDa), 25.5 min (Vn 2, 450 kDa) and 22.2 min (Vn 3, 800 kDa). The Vitellin eluted at 30.7 min in HPLC was the major protein. 3. 3. Each Vitellin consistently had two polypeptide subunits (90 and 104 kDa) and a minimum molecular weight of 194 kDa. Vn 1 and mixed Vitellins (Vn 1 + Vn 2 + Vn 3) were immunologically identical. 4. 4. The purified Vitellin has been suggested as a lipo-glyco-carotenoprotein. The amino acid composition of Vitellins has also been analyzed.
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Purification and characterization of Vitellin from the mature ovaries of prawn, Penaeus monodon
Comparative Biochemistry and Physiology Part B: Comparative Biochemistry, 1993Co-Authors: Ching-fong Chang, Fung-yi Lee, Yung-sen HuangAbstract:Abstract 1. 1. A purified Vitellin was isolated from the mature ovaries of the prawn ( Penaeus monodon ) after purification with gel filtration, hydroxylapatite, DEAE-Sephacel and polyacrylamide gel electrophoresis. 2. 2. Eight polypeptide subunits and a molecular weight of 492 kDa were suggested as being present in the purified Vitellin. 3. 3. Polypeptide subunits are associated with each other through non-disulfide bonds, and the subunits of the purified Vitellin were easily rearranged during the purification. 4. 4. It has been suggested that the purified Vitellin is a lipo-glyco-carotenoprotein. The amino acid composition of the Vitellin has also been analyzed.
Massimo Mazzini - One of the best experts on this subject based on the ideXlab platform.
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Vitellin cleavage products are proteolytically degraded by ubiquitination in stick insect embryos
Micron (Oxford England : 1993), 2003Co-Authors: Antonella Cecchettini, Massimo Masetti, Massimo Mazzini, Maria Teresa Fernanda Locci, Anna Maria Fausto, Gabriella Gambellini, Franco GiorgiAbstract:Abstract Vitellin polypeptides are proteolytically processed in ovarian follicles and embryos of the stick insect Carausius morosus. Data show that Vitellin polypeptide A3 of 54 kDa is processed to yield polypeptide A3∗ of about 48 kDa upon completion of ovarian development, whereas Vitellin polypeptide A2 of 90 kDa yields polypeptide E9 during embryonic development. As Vitellin polypeptides are processed, polypeptides A3∗ and E9 are transferred from the yolk granules to the cytosolic space of the vitellophages and start to express a ubiquitin reactivity. At the confocal microscope, anti-ubiquitin antibodies label specifically numerous small yolk granules and the cytosolic space of vitellophages. During embryonic development, ubiquitin carrying granules undergo acidification in much the same way as larger yolk granules. However, only these latter organelles are capable of converting a latent cysteine pro-protease into an active yolk protease upon acidification of their luminal space. These data are interpreted as indicating that ubiquitin-like polypeptides are restricted to small granules throughout ovarian and embryonic development, and that Vitellin cleavage products are ubiquitinated following acidification of large yolk granules and transfer to the cytosolic space of the vitellophages.
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oocyte growth follicle cell differentiation and Vitellin processing in the stick insect carausius morosus br phasmatodea
International Journal of Insect Morphology & Embryology, 1993Co-Authors: Franco Giorgi, Paolo Lucchesi, Antonella Cecchettini, Massimo MazziniAbstract:Abstract Ovarian growth in stick insects (Phasmatodea) was examined ultrastructurally and cytochemically with a view to studying: (1) the kinetics of oocyte growth and the staging characteristics of ovarian follicles undergoing vitellogenesis; (2) the endocytic capability of the growing oocyte, including the post-endocytic fate of the Vitellins sequestered by the oocyte during vitellogenesis; (3) the differentiation of the follicular epithelium in relation to the appearance of intercellular spaces and the extracellular release of a follicle cell product. These structural observations were interpreted in relation to the nature and kinetics of the Vitellin processing in follicles undergoing vitellogenesis.
Colin R. Janssen - One of the best experts on this subject based on the ideXlab platform.
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Effects of methoprene, nonylphenol, and estrone on the vitellogenesis of the mysid Neomysis integer
General and comparative endocrinology, 2006Co-Authors: An Ghekiere, Tim Verslycke, Colin R. JanssenAbstract:The induction of the female-specific protein, vitellogenin, in male fish is a well-established endpoint to assess exposure to estrogen-like chemicals. The use of vitellogenesis as a biomarker for xenobiotic exposure in egg-laying invertebrates, however, is still relatively unexplored. Recently, we developed a quantitative enzyme-linked immunosorbent assay (ELISA) for Vitellin in Neomysis integer (Crustacea: Mysidacea) to study mysid vitellogenesis and its potential disruption by xenobiotics. In this study, gravid mysids were exposed to methoprene, nonylphenol, and estrone for 96 h. All methoprene-exposed (0.01, 1, and 100 microg/L) animals had lower Vitellin levels compared to the control animals, though this effect was not statistically significant. Exposure to nonylphenol resulted in significantly induced Vitellin levels in the lowest exposure concentration (0.01 microg/L), whereas no effects were observed at higher concentrations. Estrone significantly decreased Vitellin levels at the highest test concentration (1 microg/L). These results indicate that mysid vitellogenesis can be disrupted following chemical exposure. Difficulties in the interpretation of the observed chemical-specific and concentration-specific responses in this study highlight the need for a better understanding of hormone regulation of crustacean vitellogenesis.
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Development of a quantitative enzyme-linked immunosorbent assay for Vitellin in the mysid Neomysis integer (Crustacea: Mysidacea).
Comparative biochemistry and physiology. Part A Molecular & integrative physiology, 2005Co-Authors: An Ghekiere, Tim Verslycke, Martina Fenske, Charles R. Tyler, Colin R. JanssenAbstract:Mysid crustaceans have been put forward by several regulatory bodies as suitable test organisms to screen and test the potential effects of environmental endocrine disruptors. Despite the well-established use of mysid reproductive endpoints such as fecundity, egg development time, and time to first brood release in standard toxicity testing, little information exists on the hormonal regulation of these processes. Control of vitellogenesis is being studied intensively because yolk is an excellent model for studying mechanisms of hormonal control, and vitellogenesis can be chemically disrupted. Yolk protein or Vitellin is a major source of nourishment during embryonic development of ovigorous egg-laying invertebrates. The accumulation of Vitellin during oocyte development is vital for the production of viable offspring. In this context, we developed a competitive enzyme-linked immunosorbent assay (ELISA) for Vitellin of the estuarine mysid Neomysis integer. Mysid Vitellin was isolated using gel filtration, and the purified Vitellin was used to raise polyclonal antibodies. The ELISA was sensitive within a working range of 4 to 500 ng Vitellin/mL. Serial dilutions of whole body homogenates from female N. integer and the Vitellin standard showed parallel binding curves, validating the specificity of the ELISA. The intra- and interassay coefficients of variation were 8.2% and 13.8%, respectively. Mysid Vitellin concentrations were determined from ovigorous females and eggs at different developmental stages. The availability of a quantitative mysid Vitellin ELISA should stimulate further studies on the basic biology of this process in mysids. Furthermore, it could provide a means to better understand and predict chemically induced reproductive effects in mysids.
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Purification and characterization of Vitellin from the estuarine mysid Neomysis integer (Crustacea; Mysidacea).
Comparative biochemistry and physiology. Part A Molecular & integrative physiology, 2004Co-Authors: An Ghekiere, Tim Verslycke, Lina De Smet, Jozef Van Beeumen, Colin R. JanssenAbstract:Invertebrates account for roughly 95% of all animals, yet surprisingly, little effort has been invested to understand their value in signaling potential environmental endocrine disruption. There has been, however, much recent attention on vitellogenin induction in egg-laying invertebrates and vertebrates as indicators of exposure to estrogenic xenobiotics. Mysid shrimp (Crustacea: Mysidacea) have been put forward by several researchers and regulatory bodies (e.g., US-EPA) as suitable test organisms for the evaluation of environmental endocrine disruption. In view of developing sensitive assays to study endocrine disruption in the estuarine mysid Neomysis integer, we isolated and characterized Vitellin, the major yolk protein in eggs. Vitellin was purified using gel filtration and characterized by electrophoresis using different staining procedures. Specific (as shown by Western blotting) polyclonal antibodies were produced in rabbit against the purified Vitellin of N. integer. These antisera will be used to develop immunoassays to study vitellogenesis in mysids and to detect potential stimulatory or inhibitory effects of endocrine disruptors on the production of Vitellin.
