Purification and characterization of the female-specific protein (vitellogenin) in mature female hemolymph of the prawn,Penaeus monodon

Transcriptomic changes across vitellogenesis in the black tiger prawn (Penaeus monodon), neuropeptides and G protein-coupled receptors repertoire curation

The black tiger prawn (Penaeus monodon) is one of the most commercially important prawn species world-wide, yet there are currently key issues that hinder aquaculture of this species, such as low spawning capacity of captive-reared broodstock females and lack of globally available fully domesticated strains. In this study, we analysed the molecular changes that occur from vitellogenesis to spawning of a fully domesticated population of P.monodon (Madagascar) using four tissues [brain and thoracic ganglia (central nervous system - CNS), eyestalks, antennal gland, and ovary] highlighting differentially expressed genes that could be involved in the sexual maturation. In addition, due to their key role in regulating multiple physiological processes including reproduction, transcripts encoding P.monodon neuropeptides and G protein-coupled receptors (GPCRs) were identified and their expression pattern was assessed. A few neuropeptides and their putative GPCRs which were previously implicated in reproduction are discussed. We identified 573 differentially expressed transcripts between previtellogenic and vitellogenic stages, across the four analysed tissues. Multiple transcripts that have been linked to ovarian maturation were highlighted throughout the study, these include vitellogenin, Wnt, heat shock protein 21, heat shock protein 90, teneurin, Fs(1)M3, hemolymph clottable proteins and some other candidates. Seventy neuropeptide transcripts were also characterized from our de novo assembly. In addition, a hybrid approach that involved clustering and phylogenetics analysis was used to annotate all P. monodon GPCRs, revealing 223 Rhodopsin, 100 Secretin and 27 Metabotropic glutamate GPCRs. Given the key commercial significance of P.monodon and the industry requirements for developing better genomic tools to control reproduction in this species, our findings provide a foundation for future gene-based studies, setting the scene for developing innovative tools for reproduction and/or sexual maturation control in P. monodon.

Identification and Characterization of Reference Genes for Normalizing Expression Data from Red Swamp Crawfish Procambarus clarkii

qRT-PCR is a widely used technique for rapid and accurate quantification of gene expression data. The use of reference genes for normalization of the expression levels is crucial for accuracy. Several studies have shown that there is no perfect reference gene that is appropriate for use in all experimental conditions, and research on suitable reference genes in red swamp crawfish (Procambarus clarkii) is particularly scarce. In this study, eight commonly used crustacean reference genes were chosen from P. clarkii transcriptome data and investigated as potential candidates for normalization of qRT-PCR data. Expression of these genes under different experimental conditions was examined by qRT-PCR, and the stability of their expression was evaluated using three commonly used statistical algorithms, geNorm, NormFinder and BestKeeper. A final comprehensive ranking determined that EIF and 18S were the optimal reference genes for expression data from different tissues, while TBP and EIF were optimal for expression data from different ovarian developmental stages. To our knowledge, this is the first systematic analysis of reference genes for normalization of qRT-PCR data in P. clarkii. These results will facilitate more accurate and reliable expression studies of this and other crustacean species.

Effects of 4-nonylphenol and 17alpha-ethynylestradiol exposure in the Sydney rock oyster, Saccostrea glomerata: Vitellogenin induction and gonadal development

Adult Saccostrea glomerata were exposed to environmentally relevant concentrations of 4-nonylphenol (1microg/L and 100microg/L) and 17alpha-ethynylestradiol (5ng/L and 50ng/L) in seawater over 8 weeks. Exposures were performed to assess effects on vitellogenin induction and gonadal development during reproductive conditioning. Chronic direct estrogenicity within gonadal tissue was assessed via an estrogen receptor-mediated, chemical-activated luciferase reporter gene-expression assay (ER-CALUX). Estradiol equivalents (EEQ) were greatest in the 100microg/L 4-nonylphenol exposure (28.7+/-2.3ng/g tissue EEQ) while 17alpha-ethynylestradiol at concentrations of 50ng/L were 2.2+/-1.5ng/g tissue EEQ. Results suggest 4-nonylphenol may be accumulated in tissue and is partly resistant to biotransformation; maintaining its potential for chronic estrogenic action, while 17alpha-ethynylestradiol, although exhibiting greater estrogenic potency on biological endpoints possibly exerts its estrogenic action before being rapidly metabolised and/or excreted. A novel methodology was developed to assess vitellogenin using high-performance liquid chromatography (HPLC). Exposure to both 17alpha-ethynylestradiol (50ng/L) and 4-nonylphenol (100microg/L) produced increases in vitellogenin for females, whereas males exhibited increases in vitellogenin when exposed to 50ng/L 17alpha-ethynylestradiol only. Females exhibited greater vitellogenin responses than males at 50ng/L 17alpha-ethynylestradiol only. Histological examination of gonads revealed a number of individuals exhibiting intersex (ovotestis) in 50ng/L 17alpha-ethynylestradiol exposures. Male individuals in 1microg/L and 100microg/L 4-nonylphenol exposures and 5ng/L 17alpha-ethynylestradiol were at earlier stages of spermatogenic development than corresponding controls.

Characterization of vitellin from the ovaries of the banana shrimp Litopenaeus merguiensis

Vitellin (Vt) was purified from ovary extracts of mature females of the banana shrimp Litopenaeus merguiensis using DEAE-Sephacel and Superdex 200 columns. Native Vt had an apparent molecular mass of 398 kDa as determined by native PAGE and by gel filtration chromatography. Under reducing and denaturing conditions (SDS-PAGE), Vt is composed of two major subunits of 87 and 78 kDa, although some faint bands were also detected. The N-terminal 10 amino acids sequence of the 78 kDa subunit is identical to that of Litopenaeus vannamei Vt and very similar to that of Litopenaeus japonicus vitellogenin (Vg) as well as Litopenaeus semisulcatus Vt, with an identity of 89%. Anti-Vt polyclonal antibody raised against purified Vt shows a high specificity with only ovarian Vt and hemolymph Vg of vitellogenic shrimps in double immunodiffusion and Western blot assays. Vg and Vt concentrations in hemolymph, hepatopancreas and ovaries were measured by ELISA. Vg concentrations increased in the hemolymph in the early stages of ovarian development and declined in the maturation stages. As there were undetectable concentrations of Vg in the hepatopancreas while an elevation of Vg levels occurred in the hemolymph, during the time that Vt was accumulating in the ovaries during oogenesis, this would suggest that the contribution of Vg synthesized by the hepatopancreas only might be not sufficient for adequate development of the oocytes in the banana shrimp L. merguiensis during vitellogenesis.

Purification of vitellin from the ovary of Chinese mitten-handed crab (Eriocheir sinensis) and development of an antivitellin ELISA

Vitellin was purified from ovaries of mature female Chinese mitten-handed crab (Eriocheir sinensis) using gel filtration chromatography. Analysis by native PAGE showed the vitellin had a native molecular mass of 520 kDa, while denaturing SDS-PAGE revealed two subunits of 97 and 74 kDa. Purified vitellin was used to raise polyclonal antisera, with which an enzyme-linked immunosorbent assay (ELISA) was developed. The ELISA was sensitive and could effectively detect vitellin in the range of 7.8-500 ng. Furthermore, vitellin levels in various developmental stages of oogenesis were measured with the ELISA assay. The results indicated that levels of vitellin increased significantly from 0.22 mg/ovary at Stage II to 360.31 mg/ovary at Stage IV.

Relationship between vitellogenin and vitellin in a marine shrimp (Penaeus semisulcatus) and molecular characterization of vitellogenin complementary DNAs

The source of yolk proteins in crustacean ovaries has been the subject of controversy for several decades, and both extraovarian and intraovarian synthesized proteins have been implicated. To offer a new insight into the relationship of vitellogenin (VTG) and vitellin (VT), a comparison of extraovarian VTG and ovarian VT of the marine shrimp Penaeus semisulcatus was performed at the protein and cDNA levels. Two cDNAs (7920 and 2068 nucleotides [nt]) were sequenced for VTG from the ovary and one cDNA (7920 nt) was sequenced from the hepatopancreas. VTG cDNA from hepatopancreas was similar to VTG cDNA from ovary. Although a VTG gene was also found in the males, approximately 7.8-kilobase transcripts were only detected in the ovary and hepatopancreas of females. The mRNA expression pattern was related to the stage of ovarian development and to the molt cycle, as determined by real-time polymerase chain reaction assay. VTG and VT apoproteins were composed of two and three major subunits, respectively, as shown by SDS-PAGE. N-terminal sequences of these subunits revealed the presence of a cleavage site at a consensus motif for a subtilisin-like endoprotease in VTG and VT and an additional cleavage site in VT revealed by an unidentified endoprotease. These results indicate that penaeid shrimps constitute a unique model for vitellogenesis, showing intraovarian gene expression and synthesis of yolk protein.

The role of 20-hydroxyecdysone on the control of spider vitellogenesis

We investigated the role of 20-hydroxyecdysone (20E) on the ovarian maturation and protein levels and pattern in adult females of the spider Tegenaria atrica. In unmated females, the ovaries did not initiate vitellogenesis and levels of proteins in the hemolymph and ovaries were low. Unmated females treated with 20E showed an increase in the total amount of proteins in their hemolymph and ovaries, comparable with that in untreated mated females. Vitellogenesis was observable histologically in 20E treated unmated females as in untreated mated ones. The electrophoretic analysis of total proteins revealed a 47 kDa band expressed in the vitellogenic ovaries and hemolymph of 20E treated unmated females and untreated mated ones as in newly laid eggs. We hypothesize that this 47 kDa protein could belong to the vitellogenin-vitellin complex. We describe in this paper, for the first time in a spider, the partial characterization of putative yolk protein.

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.

Is the unique negatively charged polypeptide of crayfish yolk HDL a component of crustacean vitellin?

The yolk protein of Cherax quadricarinatus contains six major high-density lipoprotein (HDL) subunits with the approximate molecular masses of 177, 155, 106, 95, 86, and 75 kDa, of which only the 106-kDa polypeptide is negatively charged. On the basis of their molecular weights, time of appearance and disappearance, their floating density and susceptibility to enzyme degradation (by a serine proteinase), these six HDL polypeptides were classified into two subgroups. One group comprises the higher-molecular-weight compounds above 106 kDa, and the other includes the lower-molecular-weight compounds up to 95 kDa. Other than being different from the lower-molecular-weight polypeptides, the negatively charged 106-kDa polypeptide was significantly different from members of its higher-molecular-weight group belonging to a different, less abundant, yolk protein as shown by HPLC separation. Immunological studies and peptide mapping in which the 106-kDa polypeptide did not show similarity to any of the other HDL components confirmed these differences. Moreover, the amino acid composition of the 106-kDa polypeptide was different from that of known vitellin from other crustacean species. This unique negatively charged polypeptide presents an enigma as it is known to be a secondary vitellogenic-related HDL polypeptide, immunolocalized in yolk globules; however, it is different to all the other HDL polypeptides, thus presenting the question whether it is indeed a component of "classical" crustacean vitellin.

Hepatopancreas is the extraovarian site of vitellogenin synthesis in black tiger shrimp, Penaeus monodon

The site of yolk protein synthesis in crustaceans has long been a subject of controversy. The vitellogenin gene structure was partially reported only very recently in Macrobrachium rosenbergii, after which the hepatopancreas was confirmed as the extraovarian site of vitellogenin synthesis in that species. Ovaries are the most frequently reported as the site of yolk protein synthesis in penaeid shrimp. Using cDNA reversed-transcribed from mRNA isolated from the hepatopancreas of vitellogenic female shrimp, Penaeus monodon, we found that its deduced amino acid sequence had high identity of 48% with that from M. rosenbergii vitellogenin. A similar location of the intron in the sequenced region of genomic DNA was also found between these two species. We therefore concluded that the hepatopancreas the extraovarian site of vitellogenin synthesis in P. monodon in vivo. The partial structure of vitellogenin gene is presented in this study.

Determination of amino acid sequence and site of mRNA expression of four vitellins in the giant freshwater prawn, Macrobrachium rosenbergii

Four major yolk proteins, designated as vitellins (Vns) Macr-VnA, B, C, and D, were extracted from mature ovaries of Macrobrachium rosenbergii. These were purified to homogeneity by reversed-phase high performance liquid chromatography (HPLC) employing a unique separation system based on the hydrophobic properties of the Vn molecule. Using standard techniques of protein sequencing, more than 33 N-terminal and 57 internal amino acid residues were determined for each of the four Vns. The cDNA fragments encoding the four Vns were amplified by PCR using degenerate oligonucleotide primers derived from the N-terminal and internal amino acid sequences. These cDNA fragments were cloned, sequenced, and used as probes to examine the transcription of mRNAs encoding the four Vns. Significant accumulations of these mRNAs were observed in female hepatopancreas only, while mRNA expression was not detected in male hepatopancreas or any other female tissue including ovary, subepidermal adipose tissue, gill, and muscle. This is the first occasion in Crustacea in which multiple Vns were demonstrated to be synthesized simultaneously in a single tissue.

High-density lipoprotein associated with secondary vitellogenesis in the hemolymph of the crayfish Cherax quadricarinatus

The high-density lipoproteins LPI and LPII were isolated from the hemolymph of the crayfish Cherax quadricarinatus by gradient ultracentrifugation and high-performance liquid chromatography (HPLC). Both lipoproteins contained a carotenoid moiety. LPI is comprised of a single polypeptide with an approximate molecular mass of 96 kDa. LPII was composed of two similar native components, LPIIa and LPIIb, both having polypeptides of 80 and 177 kDa. Both under natural conditions and after endocrine manipulations, LPI was present in males and in females, regardless of the female reproductive stage. LPII was present only in secondary-vitellogenic females, but not during the winter reproductive arrest period. LPII was also absent from young females that had received androgenic gland implants. LPII also appeared in the hemolymph of intersex individuals from which the androgenic gland had been removed. It is therefore suggested that LPII serves as a marker indicating the onset of secondary vitellogenesis in C. quad'iariicarintus females.

Partial characterization of vitellin and localization of vitellogenin production in the terrestrial isopod, Armadillidium vulgare

Vitellins were purified separately from ovaries and eggs of the isopod, Armadillidium vulgare. Ovarian vitellin consisted of at least six proteins with relative molecular masses of 205, 200, 185, 180, 122 and 112 kDa. The larger four proteins disappeared in eggs within a week after oviposition and a 59-kDa protein appeared thereafter. The amino-terminal amino acid sequences of these vitellin proteins were identical except for the ovarian 112 kDa, egg 112 kDa and 59 kDa proteins, and showed considerable similarity to those of known vitellogenins from other animals. Comparison of tryptic peptide maps of the 122 and 112 kDa proteins from eggs on reversed-phase HPLC and sequence identification of two randomly selected peaks having the same retention times indicated that two peptides were mostly similar in sequence. PCR-assisted cloning of the 5' region of a cDNA (591 bp) encoding vitellogenin revealed the presence of a signal peptide consisting of 16 amino acid residues and clarified the structural relationship among the protein components except for the ovarian 112 kDa and the egg 59 kDa proteins. Northern blot analysis revealed that the fat body is the main vitellogenin producing organ.

Synthesis and organization of vitellogenin and vitellin molecules from the land crab Potamon potamios

We have previously reported that vitellogenin (Vg) of some female animals contained four polypeptides with molecular mass of 181, 115, 105 and 85 kDa, whereas Vg of most animals contained three polypeptides with molecular mass of 115, 105 and 85 kDa. In the present investigation, we examined whether the 181 kDa polypeptide is the precursor of 115 and 105 kDa Vg and vitellin (Vn) polypeptides. Labeling studies, using [35S]methionine on normal vitellogenic animals, showed that the radioactivity was distributed first among the 181 and 85 kDa polypeptides. SDS-PAGE analysis of purified hemolymph Vg from eyestalk ablated female animals revealed in most animals two polypeptides with an apparent molecular mass of 181 and 85 kDa. These results from in vivo experiments corroborated the view that the 115 and 105 kDa Vg and Vn polypeptides are derived from heaviest 181 kDa polypeptide. In addition it was demonstrated that hepatopancreas and ovary of Potamon potamios incubated in vitro with [35S]methionine synthesized five polypeptides with apparent molecular mass of 224, 181, 115, 105, and 85 kDa while the hepatopancreas appeared to secrete the 181, 115, 105 and 85 kDa polypeptides. The major 115, 105 and 85 kDa polypeptides were found to be components of egg Vn, while the 224 kDa polypeptide was found to be minor component of Vg and Vn from hepatopancreas and ovary extracts, respectively. We conclude that the Vn polypeptides produced by ovary are similar to those produced by hepatopancreas.

Hepatopancreas is the likely organ of vitellogenin synthesis in the freshwater prawn, Macrobrachium rosenbergii

The objective of the present study was to investigate the source of vitellogenin in the freshwater prawn, Macrobrachium rosenbergii. Ovarian development of M. rosenbergii was classified into five stages (stage I-V). Vitellin/vitellogenin was detected in the ovary and the hepatopancreas in different stages by native-PAGE and Western blotting. Two and three subunits of vitellin were observed in the ovary at the early- (I-II), mid- and late- (III-V) stages, respectively. The subunit of vitellogenin was not detected in the hepatopancreas at different stages of prawns. Hepatopancreas had positive immunocytological staining (against vitellin antibody) in different ovarian stages of prawn. Only vitellogenic oocyte but not previtellogenic oocytes and follicle cells had a positive immunocytological staining. Hepatopancreas could synthesize radiolabeled immunoreactive proteins after incubation with radiolabeled glycine on the basis of immunoprecipitation (against vitellin antiserum). Therefore, it is concluded that hepatopancreas is the most likely organ to synthesize vitellogenin in the freshwater prawn, M. rosenbergii.

Site of vitellogenin synthesis determined from a cDNA encoding a vitellogenin fragment in the freshwater giant prawn, Macrobrachium rosenbergii

Vitellogenesis is an important part of reproductive process in crustaceans, and the process is characterized by the synthesis and accumulation of yolk protein in the developing oocytes. The yolk proteins in crustaceans mainly consist of vitellogenin (Vg) and vitellin (Vn), which are respectively present in extra-oocyte tissues and intra-oocytes. The site and the process of yolk protein synthesis in crustaceans are still controversial. The synthesis site of Vg in a crustacean species, Macrobrachium rosenbergii, is determined by immunological and immunohistochemical techniques, and molecular cloning of a cDNA encoding the primary structure of Vn in this study. The hepatopancrease is clearly shown to be the synthesis site of Vg in this species. The length of Vg mRNA was estimated as about 6 kb from Northern blotting analysis. The partial primary structure of Vg gene is presented, and the post-translational processing are further discussed. For the first time, the partial primary structure of Vg gene and the synthesis site of Vg approached by molecular cloning in crustaceans are presented.

Ovarian function in the giant tiger prawn (Penaeus monodon) as determined by in vitro bioassay

Ovary tissue fragments of the giant tiger prawn Penaeus monodon were incubated in vitro with L-methionine[35S] plus L-cysteine[35S] as a metabolic labeling reagent. The labeled cytoplasmic and secreted proteins synthesized in vitro during incubations under various conditions were subjected to SDS polyacrylamide electrophoresis and visualized by autoradiography. Vitellogenin (Vg) was immunologically identified and shown to be actively synthesized and released into the incubation medium. The synthesis and release of Vg into the incubation medium was optimized and shown to be linear over a 16-h period. Comparisons between different ovarian regions and different stages of development revealed that the level of Vg synthesis and accumulation in the incubation media was variable depending on stage of development and region within the ovary. Coincubation of ovarian fragments with sinus gland extracts showed a dose-related inhibition of total protein and Vg synthesis. The in vitro ovarian bioassay is suitable for examining the effect of hormonal inputs of P. monodon.

Isolation and characterization of the female-specific protein (vitellogenin) in mature female hemolymph of the freshwater prawn, Macrobrachium rosenbergii: comparison with ovarian vitellin

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.

Isolation and characterization of the high-density lipoproteins from the hemolymph and ovary of the penaeid shrimp Penaeus semisulcatus (de Haan): apoproteins and lipids

The high-density lipoproteins (HDLs) found in the male and female hemolymph of Penaeus semisulcatus de Haan were isolated by NaBr (1.22 g/ml) followed by sucrose gradient (5-25%) ultracentrifugation. The male HDL contained one protein, lipoprotein 1 (LP1), composed of one 110-kDa peptide subunit. The female HDL contained two proteins: 1) the LP1 that was immunoidentical to the male LP1 and was similarly composed of one 110-kDa peptide subunit and 2) vitellogenin (Vg), reacting positively with the rabbit antiserum generated against vitellin (Vt) that was isolated from vitellogenic ovaries. Both Vg and Vt consisted mainly of three polypeptide subunits (200, 120, and 80 kDa) as revealed by denatured PAGE and Western blot. The LP1 from males or females did not react with the Vt rabbit antiserum. Similarly, Vg and Vt did not react with the rabbit antiserum prepared against LP1. Phospholipids (PL) constituted 71-76% of the total lipids in the hemolymph and HDLs of both male and female hemolymph. Cholesterol (Ch) amounted to 17-20%, and small amounts (5%) of diacylglycerols (DAG) were also carried by these HDLs. Both the PL and DAG contained highly unsaturated fatty acids (20:5 omega 3 and 22:6 omega 3) that are transported from the food or hepatopancreas to the tissues, including the vitellogenic ovaries in females. In the present study we show for the first time the separate lipid composition of female LP1 and Vg and compare them with the lipids attached to the Vt. Vg had a lower lipid content than LP1 (540 and 1089 mg/g protein, respectively). Differences were also found in the relative abundance of PL, Ch, and DAG classes in the LP1 in comparison with Vg. Furthermore, small amounts (approximately 3.8%) of triacylglycerols (TAG) were found only in the hemolymph of vitellogenic females, and they were associated with the Vg. Although Vg and Vt were composed of similar polypeptides, their lipid composition was different Vt, in contrast to Vg, carried considerable amounts of TAG (approximately 22%) and only trace amounts of DAG. The significance of the TAG in the hemolymph of vitellogenic females is not known, and the functional relationship between Vg and Vt requires future extensive studies. Lipids were not detected in hemocyanin that was purified from clotted hemolymph.