Vitellogenesis in the hematophagous Dipetalogaster maxima (Hemiptera: Reduviidae), a vector of Chagas' disease

Oocyte extracts of anautogenous Dipetalogaster maxima were chromatographed on an ion-exchange column in order to purify vitellin (Vt), the main insect yolk protein precursor. Purified Vt (Mr ~443 kDa) was composed of four subunits with approximate molecular weights of 174, 170, 50, and 44 kDa. Polyclonal anti-Vt antibody, which cross-reacted equally with fat body extracts and hemolymph vitellogenin (Vg), was used to measure the kinetics of Vg expression in the fat body and the levels in hemolymph. In addition, morphological and immunohistochemical changes that took place in the ovary during vitellogenesis were analyzed. The study was performed between 2 and 8 days post-ecdysis and between 2 and 25 days post-blood feeding. During the post-ecdysis period, D. maxima showed decreased synthesis of Vg and concomitantly, low levels of Vg in hemolymph (4.5 x 10(-3) microg/microl at day 4). After a blood meal, Vg synthesis in the fat body and its levels in hemolymph increased significantly, reaching an average of 19.5 microg/microl at day 20. The biochemical changes observed in the fat body and hemolymph were consistent with the histological and immunohistochemical finds. These studies showed noticeable remodeling of tissue after blood feeding.     

Characterization and quantification of yolk proteins in the lobster, Homarus americanus

Yolk protein (vitellin, Vn) and its precursor (vitellogenin, Vg) were isolated and characterized in the ovary and hemolymph, respectively, of the adult female lobster, Homarus americanus. Vn had a molecular mass of 360 kDa when analyzed by gel filtration. When analyzed by SDS-PAGE, Vn had six bands (110, 105, 94, 90, 81, and 78 kDa). An anti-Vn antiserum was developed using purified Vn, and the antiserum was used to detect Vn and Vg by ELISA and western blot techniques. ELISA analysis of hemolymph proteins separated by gel filtration indicated that Vg was similar in mass to Vn (360 kDa). However, western blots of hemolymph proteins separated by SDS-PAGE indicated that Vg contained a pair of protein subunits, 194 kDa and 179 kDa. Furthermore, the elution profiles of Vn and Vg from anion exchange chromatography indicated that Vg had a more negative charge. Thus, Vg appears to be processed after its uptake by the ovary to form Vn. Vg was undetectable in hemolymph from adult males by either ELISA or by western blot analysis. However, hemolymph levels of Vg in adult females increased 40-fold during the reproductive cycle, rising from 18 microg/mL in ovarian stage II to 789 microg/mL at stage V. This increase correlates well with oocyte growth during the cycle. Hence, this method may be useful for studying the regulation of lobster vitellogenesis.     

Multiple vitellogenins from the Haemaphysalis longicornis tick are crucial for ovarian development

Ovarian development and egg maturation are crucial processes for the success of reproduction in ticks. Three full-length cDNAs encoding the precursor of major yolk protein, vitellogenin, were obtained from cDNA libraries of the Haemaphysalis longicornis tick and designated as HlVg-1, HlVg-2 and HlVg-3. The HlVg mRNAs were found in fed females with major expression sites in the midgut, fat body and ovary. Native PAGE and Western blot demonstrated that HlVgs in the hemolymph, fat body and ovary of fed females consisted of four major polypeptides. RNAi results showed that HlVg dsRNA-injected ticks obtained lower body weight, egg weight and showed higher mortality of engorged females after blood sucking than control groups. Our results indicate that all HlVgs are essential for egg development and oviposition.     

家蝇的卵黄发生及其激素调节

用5—15%SDS-PAGE分析表明,家蝇Musce domestica viaina卵黄蛋白由三个亚基组成,其亚基分子量分别为58KD、50KD、48KD.火箭免疫电泳的结果表明,脂肪体、血淋巴和卵巢内卵黄原蛋白的变化具有密切的相关性,卵黄原蛋白在体内最早出现在羽化后30小时左右,然后迅速增加,在羽化后48小时,脂肪体和血淋巴中卵黄原蛋白含量达到最大值,卵巢开始沉积卵黄蛋白在羽化后30小时,到产卵前达到最大值,脂肪体在离体培养条件下,通过测定³H-亮氨酸掺入卵黄原蛋白的量,对不同发育时期家蝇脂肪体合成卵黄原蛋白的能力及激素的调节作用进行了研究,结果表明,羽化12小时后,合成能力迅速上升,48小时时形成高峰,60小时后迅速下跌直至产卵,其合成能力一直维持在低水平,产卵后合成能力又迅速回升,激素处理结果表明,保幼激素可以促进卵黄发生前期和后期家蝇脂肪体的卵黄原蛋白合成,20-羟基蜕皮酮可以大幅度促进卵黄发生期家蝇脂肪体的卵黄原蛋白合成.当二种激素共同处理时,对卵黄发生前期和卵黄发生期的家蝇脂肪体有协同促进作用,而对卵黄发生后期的脂肪体没有这种作用.本文还对家蝇卵黄发生过程中脂肪体、血淋巴和卵巢三者之间的关系及家蝇卵黄发生的激素调节进行了讨论.     

天蚕卵黄原蛋白的合成、运转与沉积

系统测定了天蚕Antheraea yamamai吐丝结茧至成虫期脂肪体、血淋巴和卵巢中卵黄蛋白和可溶性蛋白总含量的动态变化。结果表明,脂肪体是卵黄原蛋白(Vg)合成场所,Vg合成始于吐丝结茧后第4天;脂肪体、血淋巴中Vg滴度在吐丝结茧后第4天开始上升,化蛹后第6天或第8天达高峰,成虫羽化第1天则明显下降。卵巢对Vg摄取始于化蛹第1天,此后随蛹日龄逐渐上升,并渐趋平稳。同一卵巢管中卵黄蛋白(Vt)含量自顶端至基端随卵室增大而逐渐升高,不同日龄蛹中相应序号卵室的Vt含量以日龄大者为高;卵室中Vt含量与卵室体积大小呈正线性关系。电镜观察表明,Vg被卵母细胞摄入后以卵黄体形式存在,不同发育阶段卵巢中卵母细胞内卵黄体大小不同,以早期者为小;同一卵巢管中不同卵母细胞内卵黄体以顶端为小,基端明显增大,且卵黄体呈网状。     

Vitellogenin and vitellin of a millipede Spirostreptus asthenes: Occurrence,isolation and partial characterization

Vitellogenin (Vg), the yolk precursor protein and its product vitellin (Vn) have been identified in hemolymph and fat body of females and mature oocytes in the millipede Spirostreptus asthenes employing double immunodiffusion technique. These two proteins are absent in males indicating that they are female specific. Immunoelectrophoresis has shown that there is only one vitellogenic protein present in S. asthenes. Vg and Vn were isolated by gel filtration. Polyacrylamide gel electrophoresis (PAGE) analysis revealed that Vg and Vn are glycolipoproteins. Vg contains 48.8% protein, 2.2% carbohydrate and 48.9% lipid. Vn is comprised of 52% protein, 2.3% carbohydrate and 45.4% lipid. The lipid components of Vg and Vn include mainly phospholipids such as phosphatidic acid, sphingomyelin, phosphatidyl choline, phosphatidyl ethanolamine and cholesterol. On SDS-PAGE analysis both Vg and Vn yielded five sub units each. The molecular weight of the sub units of Vg was found to be 135, 115, 105, 73 and 56 kDa and those of Vn were 125, 110, 100, 68, and 53 kDa. The vitellogenic system of S. asthenes resembles that of insects. The phylogenetic relationship of the vitellogenic system of this millipede with other arthropod groups is discussed.     

Vitellogenin levels in hemolymph, ovary and hepatopancreas of the freshwater crayfish Cherax quadricarinatus (Decapoda: Parastacidae) during the reproductive cycle

The freshwater crayfish Cherax quadricarinatus is a tropical species of great interest for aquaculture. Vitellogenin (Vg), a lipoprotein precursor of the vitellum accumulated in spawned eggs, can be synthesized in the ovary and/or hepatopancreas of most crustaceans, being the hemolymph the way for transporting Vg throughout the reproductive cycle. Concentration of Vg in hemolymph, ovary and hepatopancreas of Cherax quadricarinatus adult females was measured by means of ELISA, specifically developed after purifying the native Vg. Measurements were made at four periods of the reproductive cycle: pre-reproductive, mid-reproductive, late reproductive and post-reproductive. Besides, both hepatosomatic (HSI) and gonadosomatic (GSI) indexes were determined in each period. Significant variations in Vg levels were detected in both hemolymph and hepatopancreas, being the highest values observed during the mid-reproductive period. Besides, such variations were positively correlated to the HSI. A positive correlation between Vg levels in hepatopancreas and ovary was also seen. These results support previous evidences about the central role of the hepatopancreas as a site of Vg synthesis in the studied species, together with the relevancy of hemolymph for transporting Vg from the hepatopancreas to the ovary. For aquaculture purposes, Vg monitoring in hemolymph could be used as a non-injurious method, to check the reproductive activity of C. quadricarinatus females.     

Biosynthesis of mosquito vitellogenin

Vitellogenin (Vg), the hemolymph precursor to the major yolk protein in mosquitoes, is synthesized in the fat body of blood-fed females. Mosquito Vg consists of two subunits with Mr = 200,000 and 66,000. Here, we demonstrate that both the Vg subunits are first synthesized as a single precursor. The identity of this Vg precursor was confirmed by immunoprecipitation with subunit-specific monoclonal antibodies. In cell-free translation of fat body poly (A)+ RNA, the Vg precursor had Mr = 224,000 which increased to 240,000 in the presence of canine pancreatic microsomal membranes. A precursor with Mr = 250,000 was immunoprecipitated in microsomal fractions isolated from rat bodies. With in vitro pulse labeling, the 250-kDa precursor could be detected in homogenates of fat bodies from blood-fed mosquitoes only during the first few hours accumulation of the Vg precursor was achieved by an in vitro stimulation of Vg synthesis in previtellogenic fat bodies cultured with an insect hormone, 20-hydroxyecdysone. The 250-kDa precursor was glycosylated and to a much lesser degree phosphorylated. Treatment of fat bodies with tunicamycin yielded the precursor with Mr = 226,000 which was neither glycosylated nor phosphorylated. The reduction in molecular mass of the 250-kDa Vg precursor and of both mature Vg subunits combined was similar after digestion with endoglycosidase H, indicating that glycosylation is completed prior to cleavage of the Vg precursor. In vitro pulse-chase experiments revealed rapid proteolytic cleavage of the 250-kDa precursor to two polypeptides with Mr = 190,000 and 62,000 which transformed into mature Vg subunits of 200- and 66-kDa as the last step prior to Vg secretion. This last step in Vg processing was inhibited by an ionophore, monensin, and therefore occurred in the Golgi complex. Sulfation as an additional, previously unknown, modification of mosquito Vg was revealed by the incorporation of sodium [35S]sulfate into both Vg subunits. Since sulfation of Vg was predominantly blocked by monensin, the final maturation of Vg subunits in the Golgi complex is, at least in part, due to this modification.     

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.     

Regulation of vitellogenesis in the fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae)

Studies were undertaken to investigate vitellogenesis and its regulation in female adults of the fall armyworm, Spodoptera frugiperda. A single female-specific protein, likely to be the S. frugiperda vitellogenin (Vg), appeared approximately 5 h after adult eclosion in the hemolymph of virgin females. The concentration of the protein increased with age as sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) revealed. A protein with the same relative molecular mass was also present in egg extracts, but absent from hemolymph samples from male moths. The relative molecular mass of the designated S. frugiperda Vg was determined as 164.5+/-2.5 kDa. Vitellogenic oocytes became visible 36-48 h after emergence and egg deposition began on day 3 of adult life. Vg could not be detected in the hemolymph of females decapitated directly after eclosion. When decapitated virgin females were injected with the JH-mimic methoprene (MP), the level of Vg was comparable to that in non-decapitated moths, indicating that vitellogenesis in S. frugiperda depends on juvenile hormone (JH). However, the number of vitellogenic oocytes was somewhat lower than in non-decapitated virgin females. Injection of 20-hydroxyecdysone (20E) promoted Vg production to a similar extent in decapitated female moths, but in contrast to methoprene injection, treatment with 20E never resulted in the production of vitellogenic oocytes. In vitro cultivated ovaries of adult females dissected directly after eclosion produced lower amounts of ecdysteroids than those isolated on day 1 after emergence. Our results suggest a crucial role for 20E in the induction of vitellogenesis in the noctuid S. frugiperda, while JH seems to be essential for the continued uptake of Vg by developing oocytes and may trigger 20E biosynthesis in the ovary.     

Effect of age,diet, diapause and juvenile hormone on oogenesis and the amount of vitellogenin and vitellin in the twospotted stink bug,Perillus bioculatus (Heteroptera: pentatomidae)

Vitellogenic oocytes from Perillus bioculatus have two native vitellins, Vt1 and Vt2, with molecular masses of 553 and 228 kDa, respectively. The hemolymph contains a major vitellogenin, Vg, with a molecular mass of 528 kDa that consists of three apoproteins with masses of 177, 84 and 59 kDa, respectively. Antibodies to purified Vt2 reacted with ovary extracts, egg extracts and female hemolymph, but not with male hemolymph in immunodiffusion tests. Western blots showed that anti Vt2 reacted with both Vt1, Vt2 and with Vg. Vitellogenesis starts at an ovarian score of 12 at 2.4 days after emergence. The first cycle of egg development is completed in ovaries with a score of 112 at 7.7 days. During this 5.3 day period, the ovaries of a single female incorporated 1833 &mgr;g of protein to form vitellin. Vitellogenin levels start to increase in females 2.5 days after emergence and reached 17.8 &mgr;g/&mgr;l by 5.5 days. After 5.5 days vitellogenin levels fluctuated between 9.7 and 19.9 &mgr;g/&mgr;l. Most diapausing females contained no ovarian follicles in the vitellarium and their hemolymph contained less than 1 &mgr;g/&mgr;l of vitellogenin. Treating diapausing females with 1 &mgr;g of JH III increased vitellogenin levels over 120-fold. Insects maintained on a liver-based artificial diet had lower vitellogenin levels than the controls at all sample times and did not show an increase in vitellogenin concentration until 11.5 days. Treating insects on the artificial diet with 10 &mgr;g of JH III elevated vitellogenin levels to about a fourth of that found in prey-fed insects of a comparable age. This suggests that females fed the artificial diet have low levels of essential materials needed for vitellogenin production.     

Dynamics of vitellogenin synthesis in juvenile giant freshwater prawn Macrobrachium rosenbergii

The dynamics of vitellogenin (Vg) mRNA expression and patterns of Vg and vitellin distribution in the hepatopancreas and ovary of juvenile Macrobrachium rosenbergii were examined using real-time RT-PCR and immunohistochemical methods. Eyestalk ablation was seen to induce rapid development of the gonads and Vg synthesis in females. In the female hepatopancreas, Vg mRNA expression was observed several days following ablation, after which levels increased gradually with increasing gonadosomatic index (GSI). Vitellin accumulation in the oocytes also increased with increasing Vg mRNA synthesis; expression was however negligible in the ovary. Hemolymph Vg levels in females ranged from 0.04 to 2.2 mg/ml. SDS PAGE/Western blotting analysis of hemolymph samples revealed that juvenile Vg was composed of 199 and 90 kDa subunits; the 102 kDa subunit present in adult female Vg (Okuno et al., 2002. J Exp Zool 292:417-429) could not be detected at any stage of vitellogenesis in juveniles. Vg was not detectable in non-ablated juveniles. The results of this study confirmed that the mode of involvement of eyestalk factors in regulating vitellogenesis is intrinsic to both juveniles and adults, and that a basic pattern of Vg synthesis and processing is conserved. However, the fact that juveniles are not able to produce the same Vg levels observed in adult females, and do not reach high GSI levels culminating in spawning suggests that other factors and physiological conditions specific to adult females are necessary to demonstrate full reproductive ability.     

In vivo role of 20-hydroxyecdysone in the regulation of the vitellogenin mRNA and egg development in the American dog tick, Dermacentor variabilis (Say)

Injection of the hormone 20-hydroxyecdysone (20-E) into partially fed (virgin) female adults of the American dog tick, Dermacentor variabilis, while they are attached and feeding on the rabbit host, initiated the expression of the vitellogenin (Vg) gene, and Vg protein secretion and uptake by the ovary. The induction of egg production by 20-E in this bioassay was dose dependent in the range of 1-50 times the concentration normally found in a replete, vitellogenic female. Ticks examined 4 d after the 50 x treatment were still attached to the host, had numerous enlarged vitellin-filled (brown) oocytes in their ovaries, but had not engorged to repletion. The ovaries reached weights similar to those found in untreated, replete (mated) females (pre-oviposition) while solvent-injected controls demonstrated no increase in oocyte size or increase in ovary weight. An increase in the levels of a putative Vg protein was observed in hemolymph samples collected 1, 2 and 3d post-20-E injection but was not observed in the corresponding solvent controls as determined by native PAGE. Analysis of the ecdysteroid-induced protein by tryptic digestion-mass fingerprinting and BLASTP found that the putative Vg had the strongest match to GP80 (U49934), the partial sequence for the vitellogenin protein from Boophilus microplus. A partial Vg cDNA was cloned and sequenced from replete females of D. variabilis with a high similarity to GP80. Using this message as a probe, Northern blots conducted with RNA collected from partially fed, virgin females 1, 2 and 3d post-20-E injection showed upregulation of the Vg mRNA on all 3 days. Controls injected with solvent only showed no Vg mRNA. Injections with juvenile hormone III did not stimulate Vg expression, oocyte growth or full engorgement. These studies indicate that ecdysteroids and not JH can initiate expression of the Vg gene, Vg protein synthesis and release into hemolymph, and Vg uptake into developing oocytes under bioassay conditions mimicking normal feeding on the host.     

Cypermethrin induction of vitellogenesis and ovarian development in unfed adult female Ornithodoros moubata (Acari: Argasidae)

Summary

Vitellogenesis in ticks is known to be induced by engorgement and mating. In this paper, the synthetic pyrethroid cypermethrin (CyM) is shown to induce production of yolk protein precursor, vitellogenin (Vg), and ovarian development in unengorged mated adult female Ornithodoros moubata. The levels of Vg found in the hemolymph and ovarian development induced by CyM were dose-dependent. i.e., CyM doses of more than 0.2 and 1.0 μg/tick were needed for significant increase of Vg titer in the hemolymph and yolk deposition in oocytes, respectively. Immunological and electrophoretical analyses of Vg and Vitellin (Vn) induced by CyM were identical with those induced by engorgement. Vg titer induced by CyM in unengorged females followed approximately the same time course as that in the normal engorged females. However, Vg titer induced by CyM continued to increase after day 8 and reached a maximum (95 μg/μ1) on day 10 after treatment, while Vg titer induced by engorgement decreased again after reaching a maximum (60 μg/μ1) on day 6, correlated with yolk Vn deposition in oocytes. Ovarian development induced by even high doses (10 or 20 μg/tick) of CyM was slow compared to normal development stimulated by engorgement. Oviposition was not observed in females treated with CyM.     

Ovarian Development and Vitellin of the Mushroom Fly,Lycoriella mali (Diptera: Sciaridae)

Ovarian Development and Vitellin of the Mushroom Fly, Lycoriella mali, were characterized. L. mali has a pair of ovaries, composed of 50–60 ovarioles, respectively. Ovarian development began at 1 day of pupation, and continued to become mature at 2 days after adult emergence. The vitellogenin (Vg) and vitellin (Vn) of L. mali were identified by native- and SDS-PAGE analyses. The Vn is composed of two subunits with a large subunit, L-Vn (190 kDa), and a small subunit, S-Vn (63 kDa). The Vg and Vn detected in the hemolymph and ovary, respectively, have the two equivalent subunits (190, 63 kDa), respectively. These two subunits of Vn gradually decreased in content during embryogenesis. We confirmed the presence of the Vg and Vn which were first detected in the 3 day-old female pupae by SDS-PAGE and Western blot analyses. It can be assumed that the Vn is synthesized as a precursor (Vg) in the fat body at 3 days after pupation and released into hemolymph. Then, the Vg is subsequently absorbed into the ovary at the same time. Twelve amino acid residues after the signal peptide at the N-terminus of L. mali S-Vn were sequenced and showed 70% homology to those of Anthonomus grandis vitellegenin.     

Molecular characterization of the vitellogenin receptor from the tick,Amblyomma hebraeum (Acari: Ixodidae)

We have identified the full-length cDNA encoding a vitellogenin receptor (VgR) from the African bont tick Amblyomma hebraeum Koch (1844). VgRs are members of the low-density lipoprotein receptor superfamily that promote the uptake of the yolk protein vitellogenin (Vg), from the haemolymph. The AhVgR (GenBank accession No. JX846592) is 5703 bp, and encodes an 1801 aa protein with a 196.5 kDa molecular mass following cleavage of a 22 aa signal peptide. Phylogenetic analysis indicates that AhVgR is highly similar to other tick VgRs. AhVgR is expressed in only the ovary of mated, engorged females, and is absent in all other female tissues and in both fed and unfed males. Unfed, adult females injected with a VgR-dsRNA probe to knock-down VgR expression experienced a significant delay in ovary development and started oviposition significantly later than controls. These results indicate that the expression of AhVgR is important for the uptake of Vg and subsequent maturation of the oocytes.     

Purification and characterization of biliverdin-binding vitellogenin from the hemolymph of the common cutworm,Spodoptera litura

Biliverdin-binding vitellogenin (Vg) was purified from adult female hemolymph of the common cutworm, Spodoptera litura, by using gel filtration and ion exchange chromatographies. The molecular mass of the protein was 490 kDa and it was composed of two 188-kDa subunits. Three internal amino acid sequences obtained by digestion of the protein with lysylendopeptidase showed high similarity to those of Bombyx mori Vg, supporting the purified blue protein to be vitellogenin. latroscan analyses demonstrated the presence of biliverdin in Vg that occupied 2.4% of total lipid components. Among the lipids of Vg (9.5 micrograms total lipids per 100 micrograms protein), diacylglycerol was the most predominant, followed by phospholipid, hydrocarbons, and then triacylglycerol, while in biliverdin-binding proteins (BPs) purified from larval hemolymph (3.1 micrograms total lipids per 100 micrograms protein), phospholipid was the most abundant lipid followed by diacylglycerol; hydrocarbons and triacylglycerol were minor components. Vg was first detected in the hemolymph of female pupae one day before eclosion, but injection of 5 micrograms of methoprene into a 3-day-old pupa induced Vg in the hemolymph 4 days earlier than in the control. Methoprene also induced a faster decline in BP-A and BP-B titers in the hemolymph with a corresponding increase of the Vg titer. These results suggest that juvenile hormone (JH) induces not only vitellogenesis but also the uptake of these proteins by stimulating the metamorphosis of fat body during the pupal stage.     

Juvenile hormone analog and injection effects on locust hemolymph protein synthesis

In adult female Locusta migratoria, at about day 8 after eclosion, when vitellogenin (Vg) is first produced as a result of induction by juvenile hormone (JH), the intensity of hemolymph protein electrophoretic bands at about 75 kDa and 20 kDa increases sharply, suggesting that JH may induce additional proteins. A major component of the elevated protein is persistent storage protein (PSP; subunit 74 kDa). Administration of the JH analog, methoprene, to precocene-treated adult locusts was followed by a rise in hemolymph levels of PSP but not in apolipophorin III (19 kDa), identified immunochemically and electrophoretically. The synthesis of PSP in adult fat body was confirmed by incorporation of [³H]leucine. At 48 h after treatment with methoprene, Vg synthesis was induced in females (as previously observed) and synthesis of PSP in both sexes was elevated above controls, while synthesis of apolipophorin III was not stimulated. We conclude that in adult locust fat body the synthesis of several proteins responds in different ways to the JH analog: Vg (and a 21 kDa protein described elsewhere) is induced de novo solely in females; PSP (and a 19 kDa protein described elsewhere) is stimulated in both sexes but is not fully JH-dependent; apolipophorin III is not stimulated. In these experiments, methoprene was administered both by injection in mineral oil and topically in acetone. After injection of mineral oil as a vector control, incorporation into secreted proteins was stimulated at 24 h, presumably due to a wound effect; topical application of acetone avoids this effect and is a preferred route for administration of JH analog. © 1992 Wiley-Liss, Inc.