Vitellin and vitellogenin concentrations during oögenesis in the first gonotrophic cycle of the house fly,Musca domestica

The house fly, Musca domestica, contains at least two native vitellin and two vitellogenin proteins. Both vitellins appear to have an identical vitellogenin partner. The major native vitellin has a mol. wt of 281 K Daltons, and the major native vitellogenin has a mol. wt of 283 K Daltons. These proteins are composed of three subunits with mol. wt of 48, 45 and 40 K Daltons. The relationship of the subunits to the native proteins is not known.Haemolymph vitellogenin levels are cyclical during oögenesis with no detectable amounts in previtellogenic flies and low levels in postvitellogenic flies. The highest level of vitellogenin, 10.5 μg/μl, occurred in flies with stage-7 ovaries. The vitellogenin levels during oögenesis fit a parabolic curve and the fat body vitellogenin content during oögenesis showed this same pattern.Uptake of vitellogenin into the ovary during each stage of oögenesis also fit a parabolic curve and produced a high linear correlation with haemolymph vitellogenin levels. The greatest uptake was 37 μg/stage and occurred during stage 6.     

Ovarian follicle cells are the site of vitellogenin synthesis in the Pacific abalone Haliotis discus hannai

Only a few biochemical and molecular studies on yolk proteins (vitellins) have been carried out in mollusks, mainly in bivalves, while information on prosobranch vitellogenesis is still limited. In this study, we cloned a full-length cDNA encoding vitellogenin (Vg) in the Pacific abalone Haliotis discus hannai. The complete Vg cDNA consists of 7753 nucleotides with a long open reading frame encoding 2391 amino acid residues. The deduced primary structure contains the N-terminal amino acid sequences of the 95 kDa and 150 kDa subunits of vitellin of the abalone and shows similarities to Vgs of other mollusk, fish, nematode and coral species. In common with bivalve Vgs, the abalone Vg gene was expressed only in the ovary. In situ hybridization analysis further localized Vg mRNA to the follicle cells in the ovary. We conclude that the follicle cells are the site of Vg synthesis in H. discus hannai.     

A comparative study of the size-heterogeneous high mannose oligosaccharides of some insect vitellins

Comparative studies of the carbohydrate component from vitellins of the cockroaches Blattella germanica, Blaberus discoidalis, Periplaneta americana and Simploce capitata and the locust Locusta migratoria have been conducted. Chemical, enzymatic and chromatographic analyses show that each vitellin contains variably processed high mannose type oligosaccharides. While all have a common size range they occur as two distinct classes based on the proportion of individual saccharides present. Oligosaccharide size distribution is not a characteristic of an individual animal but of the species. Because oligosaccharide heterogeneity also occurs in B. germanica vitellogenin (the hemolymph precursor of vitellin), it does not result from structural changes during or after its uptake by the egg.     

Polypeptide composition and biosynthesis of the yolk proteins in the firebrat,Thermobia domestica (insecta,thysanura)

Ion-exchange chromatography of crude ovarian extracts of the primitive insect Thermobia domestica allowed the separation, in native conditions, of major and minor vitellins of molecular weights of 300,000 and 430,000, respectively. Their polypeptide subunits were determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunotransfer using an antiserum prepared against major vitellin. This protein was resolved into large (M_r 166,000–212,000) and small (around M_r 50,000) polypeptides. Minor vitellin, on the other hand, exclusively contained small polypeptides that are immunologically different from those of the major vitellin. Vitellogenin polypeptides from the hemolymph of mature females exhibited electrophoretic mobilities and immunological properties similar to vitellin polypeptides. Pulse-chase experiments showed that the female fat body synthesizes radioactive and immunoprecipitable proteins, whose polypeptide pattern is close to that of the major vitellogenin. However, part of the primary vitellogenic polypeptides, at M_r 210,000 and 212,000, is rapidly processed to M_r 176,000 and 182,000 subunits. These two polypeptides, as well as the precursors, enter into the composition of the major hemolymph vitellogenin. Finally, processing of the still uncleaved 210,000–212,000 polypeptides takes place in the ovary, which performs the same step of vitellogenin maturation as the fat body.     

Purification and partial characterization of vitellin from the eggs of the hard tick,Dermacentor variabilis

The major yolk proteins were purified from the eggs of the hard tick, Dermacentor variabilis using gel filtration and ion exchange chromatography. Two vitellin proteins were identified and designated vitellin A (480 kilodaltons; kDa) and vitellin B (370 kDa). The isolectric points were pH 6.1 and 6.25, respectively. The absorption maxima for both proteins were 280 and 400 nm. The buoyant density of vitellin A was 1.281 g/ml and vitellin B 1.278 g/ml. The vitellins were hemoglycolipoproteins as indicated by selective staining of polyacrylamide gels, carbohydrate analyses and lipid analyses. Under reducing conditions (SDS-PAGE), vitellin A had eight major polypeptides at 135, 110, 98, 80, 67, 50, 45, and 35 kDa. Vitellin B was identical to vitellin A with the addition of a 93 kDa subunit. The only carbohydrate detectable in the proteins was mannose. The neutral lipids detected in both proteins were cholesteryl esters, triglycerides, free fatty acids and their methyl esters, and cholestrol. The only detectable phospholipid in both proteins was phosphatidylethanolamine. The purified vitellins were immunologically identical to female hemolymph proteins but not to host hemoglobin. Antivitellin antibodies to vitellin were used to identify possible locations of vitellogenin in the organs of ovipositing females.     

Proteolytic processing of the vitellogenin precursor in the boll weevil,Anthonomus grandis

The soluble proteins of the eggs of the coleopteran insect Anthonomus grandis Boheman, the cotton boll weevil, consist almost entirely of two vitellin types with M_rs of 160,000 and 47,000. We sequenced their N-terminal ends and one internal cyanogen bromide fragment of the large vitellin and compared these sequences with the deduced amino acid sequence from the vitellogenin gene. The results suggest that both the boll weevil vitellin proteins are products of the proteolytic cleavage of a single precursor protein. The smaller 47,000 M vitellin protein is derived from the N-terminal portion of the precursor adjacent to an 18 amino acid signal peptide. The cleavage site between the large and small vitellins at amino acid 362 is adjacent to a pentapeptide sequence containing two pairs of arginine residues. Comparison of the boll weevil sequences with limited known sequences from the single 180,000 M_r honey bee protein show that the honey bee vitellin N-terminal exhibits sequence homology to the N-terminal of the 47,000 M_r boll weevil vitellin. Treatment of the vitellins with an N-glycosidase results in a decrease in molecular weight of both proteins, from 47,000 to 39,000 and from 160,000 to 145,000, indicating that about 10–15% of the molecular weight of each vitellin consists of N-linked carbohydrate. The molecular weight of the deglycosylated large vitellin is smaller than that predicted from the gene sequence, indicating possible further proteolytic processing at the C-terminal of that protein. © 1993 Wiley-Liss, Inc.

1 This article is a US Government work and, as such, is in the public domain in the United States of America.

     

Characterization of vitellin protein in the twospotted spider mite, Tetranychus urticae (Acari: Tetranychidae)

In mites, vitellogenin synthesis, regulation and uptake by the oocytes as vitellin remain practically unknown. Although a partial sequence of the gene is now available, no previous studies have been conducted that describe the native vitellin protein in mites. The objective of this study was to characterize vitellin in the twospotted spider mite, Tetranychus urticae. The native twospotted spider mite vitellin migrated as a single major band with a molecular weight of 476 ± 14.5 kDa as compared to 590 ± 25.5 kDa for vitellin from the American dog tick, Dermacentor variabilis. However, isoelectric focusing analysis of native spider mite vitellin showed five bands with pI values slightly acidic to neutral (pH 5.8, 6.2, 6.7, 7.0 and 7.2), as is the case for insect and tick vitellins. Reducing conditions (SDS-PAGE) also revealed multiple subunits ranging from 290.9 to 3.6 kDa and was similar to that found in D. variabilis. Spider mite vitellin weakly bound lipids and carbohydrates compared to the tick. Unlike D. variabilis, the spider mite egg yolk protein does not bind heme. The significance of non-heme binding in mites is discussed.     

An evolutionary model for the insect vitellins

Insects can be divided into three groups based on the sizes of the polypeptide constituents of their vitellogenins and vitellins. In order to determine the relationships between these groups, antisera to the vitellins of seven insects from six taxonomic orders were used to assess immunological cross-reactivity. Antigenic relatedness was observed only between vitellins from species within the same family. Amino acid compositional data for vitellins from nine species were used to assess homology by difference matrices. The SΔQ values were similar for both intra-order and inter-order comparisons and strongly suggested relatedness. The SΔ_n comparisons supported the immunological data that indicated that the vitellins were evolving rapidly. For most insect vitellins there are two distinct size classes of polypeptides that seem to be derived from a single asymmetric proteolytic cleavage of a precursor. We propose a model that suggests that the different size polypeptides represent distinct domains and that in the evolution of the vitellogenin genes of the Diptera and Hymenoptera there has been domain elimination.     

Postendocytic Provitellin Processing in the Growing Oocyte of the Short Horned Grasshopper, Oxyajaponicajaponica (Orthoptera: Acrididae)

Polyclonal antibodies made against 86 kDa (86 k), 80 kDa (80 k) and 54 kDa (54 k) vitellins of Oxya japonica japonica are used for Western blotting. Anti‐80k vitellin antibody is cross‐reacted with a 95 kDa (95 k) vitellin. While 95 k vitellin is present both in the female hemolymph and in the oocyte, 80 k vitellin is detected only in the oocyte and the laid egg. In the growing oocytes, as 95 k vitellin is faded out gradually, 80 k vitellin is accumulated increasingly, indicating postendocytic processing of 95 k vitellin brings 80 k vitellin. Further conforming the hypothesis, partial digestion of 95 k vitellin with pepsin and α‐chymotrypsin makes several protein bands of molecular weight around 80 kDa. Thus, the 95k vitellin may have a cleavage site (s) to produce 80 k vitellin which forms fairly stable tertiary structure. In the reduced condition (20 mM glutathion), both 95 k and 80 k vitellins were digested throughly by endogenous proteinase at pH 4. Both 86 k and 54 k vitellins, respectively, show no apparent molecular weight changes in the growing oocyte and in the hemolymph.     

Species-specific oocyte proteins as molecular markers for Lineus taxonomy

The yolk proteins from the eggs of five species of thenemertean genus Lineus were analysed and theresulting data were used to define L. longissimus, L. sanguineus, L. lacteus, L. ruber, and L. viridis as distinct taxa (species to date). All fivespecies have at least one large (80–60 kDa) and onemedium sized (45–30 kDa) vitellin subunit, but thereare significant differences in the number and sizes ofthe molecular subunits. The large and medium sizedvitellin components of all the species areglycosylated, except for the 145 kDa protein of L. sanguineus. Rabbit antibodies to the L. lacteus vitellin subunits cross-reacted withthe vitellin subunits in the eggs of the otherspecies. The vitellin components of these five speciesof nemertean are very similar. Two species, L.ruber and L. viridis, lay their eggsin gelatinous masses, and the electrophoretic patternsof the jelly proteins show that the physicalconsistency of the jelly depends on molecular weightsof the components. The egg mass of L. viridis contains smaller proteins than the egg massof L. ruber. The repeatablespecies-specific patterns of vitellin componentsprovide a useful complement to the usual taxonomiccriteria.     

Yolk proteins during ovary and egg development of mature female freshwater crayfish (Cherax quadricarinatus)

Vitellins from ovaries and eggs at different stages of development in freshwater crayfish (Cherax quadricarinatus) were examined by chromatography, PAGE and SDS-PAGE. With these methods, two forms of vitellin (Vt1 and Vt2) were observed in ovaries and eggs (stages I and V). In ovaries in secondary vitellogenesis, native molecular mass was 470 (Vt1) and 440 (Vt2) kDa. The electrophoretic pattern of the eggs proved to be more complex. The protein molecular mass depend on the development stage of the egg: stage I, 650 kDa (Vt1) and 440 kDa (Vt2); stage V, 390 kDa (Vt1) and 340 kDa (Vt2). The identified vitellins appear to be lipo-glycocarotenoprotein. A similar vitellin polypeptide composition was observed in the two forms of vitellin from ovaries and eggs in stage V. In ovaries the SDS-PAGE analysis showed four subunits with molecular weights of approximately 180, 120, 95 and 80 kDa (Vt1 and Vt2). The polypeptide composition in the two forms of vitellins in stage I and stage III eggs were different at 195, 190, 130 and 110 kDa (Vt1) and 116 and 107 kDa (Vt2). On the other hand, in stage V eggs, 110, 95, 87 and 75 kDa (Vt1 and Vt2) were identified. Two antibodies (Ab1 and Ab2) were prepared against the purified proteins of stage V eggs and their specificity was demonstrated by radial immunoprecipitation, and Western blotting analysis. Two forms of vitellins were also found in stage V eggs after chromatography on Sepharose CL-2B column and hydroxylapatite and polyacrylamide gel electrophoresis.     

Biochemical sex dimorphism in Lineus lacteus

Egg-specific and sperm-specific proteins fromLineus lacteus females and males were investigated byanalytical electrophoreses. These major sex-specificproteins define the sexual dimorphism of biochemicalmetabolism and are useful for studying vitellogenesisand spermatogenesis. The major yolk proteins in theeggs of the nemertean, Lineus lacteus, wereidentified by gradient gel electrophoresis. The 2vitellin proteins were designated vitellin V1 (460 kDa) andvitellin V2 (260 kDa). The vitellins wereidentified as lipoglycoproteins by selective staining.Three major vitellin subunits (75, 41 and 40 kDa) werefound in oocytes of L. lacteus byelectrophoresis under denaturing conditions(SDS-PAGE). Polyclonal antibodies were raised to eachvitellin subunit. The binding of these rabbitantibodies to vitellins V1 and V2 showed that vitellinV1 contained a single major 75 kDa polypeptide, whilevitellin V2 had two major polypeptides (41 and 40 kDa).Five male-specific proteins (52, 50, 41, 35 and 32 kDa) wereidentified in the sperm of Lineuslacteus by gradient gel electrophoresis. Four lowmolecular weight proteins (18–13 kDa) can also be usedas molecular markers of male sexual maturation. Theseproteins were nucleosomal core histones. The chromatinof L. lacteus sperm contained onlyhistones as no protamines or protamine-like proteinswere detected. But the sperm nucleosomal protein maynot be entirely somatic-histones, as a sperm-specifichistone (Sp H) was also found.     

The vitellogenin of Leucophaea maderae: Synthesis as a large phosphorylated precursor

Phosphorylation of vitellogenin (yolk protein precursor) and vitellin (major yolk protein) polypeptides of Leucophaea maderae was studied by [³²P]ortho phosphate labeling and subsequent sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) autoradiography. The vitellogenin molecule was isolated from the hemolymph and fat body by antibody precipitation and high-performance liquid chromatography (HPLC), and shown to consist of at least five polypeptides (“subunits”) which had apparent molecular masses of 155, 112, 95, 92 and 54 kD. Labeling studies with ³²P showed that the covalently attached phosphorus was distributed in an uneven fashion among the five polypeptides. The two heavily-phosphorylated polypeptides, 112 and 54 kD, corresponded to the large and small, mature vitellin subunits. Quantitative SDS-PAGE analysis of long-term ³²P-labeled vitellin showed that these large and small “subunits” contained 55 and 30%, respectively, of the total radioactivity.When fat body was pulse-labeled with ³²P we found a heavily-phosphorylated intracellular 215 kD polypeptide which was precipitable with anti-vitellogenin. The synthesis of this intracellular precursorform of vitellogenin (pre-Vg) was under absolute juvenile hormone control. In vitro³²P pulse-chase experiments showed that pre-Vg was proteolytically processed within the fat body into some (or possibly all) of the mature vitellogenin subnits. Furthermore, peptide mapping confirmed that all of the phosphorylated vitellogenin subunits were derived from pre-Vg. Since previous studies have shown that phosphoserine residues account for essentially all of the covalently-attached phosphorus of the native vitellogenin molecule, we speculate that the asymmetric pattern of vitellogenin and vitellin subunit-phosphorylation is due to an uneven distribution of phosphoserine residues along the initial pre-Vg polypeptide chain. Finally, we conclude that phosphorylation of vitellogenin occurred post-translationally in the fat body endoplasmic reticulum because we could identify ³²P-labeled pre-Vg in purified microsomal vesicles but not in nascent vitellogenin polypeptide chains attached to vitellogenin polyribosomes.     

Mosquito cathepsin B-like protease involved in embryonic degradation of vitellin is produced as a latent extraovarian precursor

Here we report identification of a novel member of the thiol protease superfamily in the yellow fever mosquito, Aedes aegypti. It is synthesized and secreted as a latent proenzyme in a sex-, stage-, and tissue-specific manner by the fat body, an insect metabolic tissue, of female mosquitoes during vitellogenesis in response to blood feeding. The secreted, hemolymph form of the enzyme is a large molecule, likely a hexamer, consisting of 44-kDa subunits. The deduced amino acid sequence of this 44-kDa precursor shares high similarity with cathepsin B but not with other mammalian cathepsins. We have named this mosquito enzyme vitellogenic cathepsin B (VCB). VCB decreases to 42 kDa after internalization by oocytes. In mature yolk bodies, VCB is located in the matrix surrounding the crystalline yolk protein, vitellin. At the onset of embryogenesis, VCB is further processed to 33 kDa. The embryo extract containing the 33-kDa VCB is active toward benzoyloxycarbonyl-Arg-Arg-para-nitroanilide, a cathepsin B-specific substrate, and degrades vitellogenin, the vitellin precursor. Both of these enzymatic activities are prevented by trans-epoxysuccinyl-L-leucylamido-(4-guanidino)butane (E-64), a thiol protease inhibitor. Furthermore, addition of the anti-VCB antibody to the embryonic extract prevented cleavage of vitellogenin, strongly indicating that the activated VCB is involved in embryonic degradation of vitellin.     

Species-specific oocyte proteins as molecular markers for Lineus taxonomy

The yolk proteins from the eggs of five species of thenemertean genus Lineus were analysed and theresulting data were used to define L. longissimus, L. sanguineus, L. lacteus, L. ruber, and L. viridis as distinct taxa (species to date). All fivespecies have at least one large (80–60 kDa) and onemedium sized (45–30 kDa) vitellin subunit, but thereare significant differences in the number and sizes ofthe molecular subunits. The large and medium sizedvitellin components of all the species areglycosylated, except for the 145 kDa protein of L. sanguineus. Rabbit antibodies to the L. lacteus vitellin subunits cross-reacted withthe vitellin subunits in the eggs of the otherspecies. The vitellin components of these five speciesof nemertean are very similar. Two species, L.ruber and L. viridis, lay their eggsin gelatinous masses, and the electrophoretic patternsof the jelly proteins show that the physicalconsistency of the jelly depends on molecular weightsof the components. The egg mass of L. viridis contains smaller proteins than the egg massof L. ruber. The repeatablespecies-specific patterns of vitellin componentsprovide a useful complement to the usual taxonomiccriteria.     

Vitellin-binding proteins in the nematode Oscheius tipulae (Nematoda, Rhabditida)

We describe the first application of a non-radioactive ligand-blotting technique to the characterization of proteins interacting with nematode vitellins. Chromatographically purified vitellins from the free-living nematode Oscheius tipulae were labeled with fluorescein in vitro. Ligand-blotting assays with horseradish peroxidase-conjugated anti-fluorescein antibodies showed that labeled vitellins reacted specifically with a polypeptide of approximately 100 kDa, which we named P100. This polypeptide is a specific worm's vitellin-binding protein that is present only in adult worms. Blots containing purified O. tipulae vitellin preparations showed no detectable signal in the 100 kDa region, ruling out any possibility of yolk polypeptides self-assembling under the conditions used in our assay. Experiments done in the presence of alpha-methyl mannoside ruled out the possibility of vitellins binding to P100 through mannose residues. Triton X-114 fractionation of whole worm extracts showed that P100 is either a membrane protein or has highly hydrophobic regions.     

Vitellogenin sequestration by Simulium oocytes: the effect of Onchocerca infection

Abstract. The effects of Onchocerca infection on Simulium ornatum Meigen vitellogenesis were investigated. Vitellogenesis is triggered by ingestion of blood and is therefore linked to disease transmission. Vitellin subunits were described for the first time in the Simuliidae. In the British blackfiy S.ornatum , vitellin in the ovaries consists of two subunits, with a large subunit of molecular weight 200 kDa and a small subunit of 68 kDa. Simulium ornatum vitellin was recognized by polyclonal antibodies produced from Aedes aegypti (L.) vitellin. When blackflies were injected with Onchocerca lienalis (Stiles) microfilariae, there was a significant reduction in the amount of vitellin in the ovaries at 24, 34 and 50 h post blood-feeding.     

Yolk proteins and their plasmatic precursor in the tetraploid Odontophrynus americanus (Amphibia, Anura)

The vitellogenin of Odontophrynus americanus is a large (426.5 kDa) plasmatic protein. The vitellogenin is composed of two different phosphoglycopeptides: VTG1 = 207.5 kDa and VTG2 = 202.4 kDa. The vitellins originating from the partial proteolysis of the plasmatic vitellogenin on the ovary cells are composed of lipovitellins and phosphoproteins. Lipovitellin 1 has two glycopeptides with different amino acid sequences as determined by peptide mapping (LV1 alpha, 104.6 kDa; and LV1 beta, 92.6 kDa). Lipovitellin 2 is composed of three kinds of polypeptides (LV2 alpha, 31.7 kDa; LV2 beta, 29.7 kDa; LV2 gamma, 27.8 kDa). There are three phosphopeptides in the yolk: phosvitin (PV, 37.4 kDa) and phosvettes 1 (PVT1, 27.7 kDa) and 2 (PVT2, 26.1 kDa).     

Purification and characterization of honey bee vitellogenin

A protocol has been developed for the purification of vitellogenin from the honey bee, Apis mellifera. Purification allows for the first characterization of a vitellogenin from the large order Hymenoptera. Hymenopteran vitellogenins are unusual among insect vitellogenins in that they contain only one type of apoprotein. The honey bee vitellogenin was isolated from hemolymph of honey bee queens by a combination of density gradient ultracentrifugation, ion-exchange chromatography, and affinity chromatography. The native vitellogenin particle is a very high density glycolipoprotein containing approximately 91% protein, 7% lipid, and 2% carbohydrate. Phospholipid and diacylglycerol are the major lipid components. The equilibrium density (1.28 g/ml) is the same as that for Manduca sexta vitellogenin, which contains a much higher proportion of lipid. The covalently bound carbohydrate moiety of the particle is high in mannose. The amino acid composition of vitellogenin is similar to those of vitellogenins from other insect species. The N-terminal amino acid sequence of the apoprotein was determined, the first such sequence for any insect vitellogenin. When analyzed by sodium dodecyl sulfate (SDS)-gel electrophoresis, A. mellifera vitellogenin resolved into a single band with an apparent Mr of 180,000. Gel filtration under reducing and native conditions yielded estimated Mr values of about 300,000.     

Gonad maturation,morphological and physiological changes during the first reproductive cycle of the crayfish Cherax quadricarinatus female

Summary

Concurrent morphological, anatomical and physiological changes took place during the first reproductive cycle in the Australian red-claw crayfish Cherax quadricarinatus, which prepared the female for spawning and holding of the newly deposited eggs. The endopod became longer and wider than the exopod and developed a mixture of plumose and long thin simple (ovigerous) setae. Small oocytes (0.24±0.05 mm) were present in the immature ovary. The growing ovary contained two distinct oocyte populations: one consisted of small (0.55±0.07 mm), barely growing oocytes, while the other consisted of large oocytes, which increased in size continuously (0.73 to 2.55 mm) until egg laying took place. A gradual change in the relative abundance of ovarian polypeptides occurred until the late vitellogenic stage (large oocytes < 1.8 mm). Three predominant female-specific, SDS-PAGE separated, polypeptides were observed (103, 78 and 73 kDa) that may represent vitellin subunits. The most abundant carotenoid in the ovary was astaxanthin, while β-carotene was present at a lower concentration. The strong correlation between the increasing diameter of the oocyte and the concentration of astaxanthin in the ovary and in the hemolymph suggested an association of astaxanthin with vitellin and vitellogenin.