Control of juvenile hormone biosynthesis during the reproductive cycle of a viviparous cockroach. I. Activation and inhibition of corpora allata

An in vitro radiochemical assay has been used to determine the juvenile hormone (JH) synthetic capacity of denervated and transplanted corpora allata (CA) of female Diploptera punctata. CA maintained in vitro over a 24-hr period do not increase their rate of JH synthesis whether taken from females in which they would undergo a dramatic increase in vivo (just before vitellogenesis) or from females in which CA synthesize JH at a low rate for an extended period (as in pregnancy). However, when CA are denervated and allowed to remain in vivo, a normal cycle of JH synthesis is observed in mated females. In virgin females, which do not normally mature eggs, the denervation mimics mating in that the CA undergo a synthetic cycle and oocytes are matured. Denervation of CA of young pregnant females (16% gestation) does not result in an immediate cycle of synthesis similar to that of mated females, nor do 0-day CA transplanted to allatectomized pregnant females exhibit such a cycle. However, inactive CA from the pregnant females transplanted to allatectomized 0-day animals promptly undergo a cycle of JH synthesis with an associated maturation of oocytes. From these results it is concluded that the integrity of the nerves of CA is required for inhibition of synthetic activity, whereas some factor in the hemolymph, not present in pregnant females, is responsible for activation and maintenance of the JH synthetic cycle.     

Ecdysteroid hormone titer and its relationship to vitellogenesis in the soft tick, Ornithodoros moubata (Acari: Argasidae)

A blood meal is required for reproduction in most argasid female ticks. The blood meal appears to stimulate an organ in the posterior end to produce a fat body stimulating factor (FSF), which is thought to be an ecdysteroid, to induce vitellogenin (Vg) synthesis. In this study, the relationship of vitellogenesis and ecdysteroids was investigated by measuring Vg and ecdysteroid titers while observing oocyte development and oviposition in mated and virgin females. Oviposition occurred from day 10 after engorgement in mated females and continued up to 40-50 days, whereas egg maturation and oviposition did not occur in virgin females. Vg titers in the hemolymph peaked on day 6 after engorgement and subsequently declined in mated females. Interestingly, Vg synthesis occurred and ovarian development progressed to the development of early vitellogenic oocytes in virgin females but oocyte maturation and oviposition did not occur. Topical application of ecdysteroids induced oviposition in fed virgin females indicating that ecdysteroids may induce oviposition. Concentrations of ecdysteroids for 20 days after engorgement revealed several peaks in mated female whole body extracts, but no peaks in virgin female extracts. In the hemolymph of only mated females, ecdysteroid titers showed two peaks that followed the early peak of ecdysteroids in the whole body on day 4 and 6 after engorgement. In addition, ecdysteroids in the reproductive tissues increased with the development of the ovary in mated females and this increase coincided with the latter peaks of the whole body. These observations indicate that physiological elevation of ecdysteroids accelerate Vg synthesis, and may induce egg maturation and stimulate oviposition in fed mated Ornithodoros moubata females.     

The activity and stability of injected juvenile hormones (JH I, JH II, and JH III) in last-instar larvae and adult females of the cockroach Nauphoeta cinerea.

The relative activities of the three known juvenile hormones (JHs) injected in olive oil are investigated in a larva test, a vitellogenin test, and an ovary growth test. The degree and character of juvenilization obtained after injection of JHs is dependent on the developmental stage at the time of injection, on the dose, and on the kind of JH used. In all developmental stages investigated JH I and JH II have similar and up to 10-fold higher juvenilizing activity than JH III. Measurement of the exogenous JH I and JH III titers at different developmental stages reveals that until at least 2–3 days after injection, the titer of JH III in hemolymph is higher than that of JH I and that only 1% or less of the injected JH circulates in hemolymph. This indicates that the difference in juvenilizing activity between JH I and JH III cannot be due to different elimination rates and suggests that JH I and JH III have different modes of action in larval Nauphoeta. For the vitellogenin and the ovary growth test decapitated adult females are used. Injection of small doses of each JH induces the synthesis of vitellogenin while high doses of each JH have to be injected to stimulate oocyte growth. Thus in adult females the three JHs have similar relative activities.     

Study of the synthesis of vitellogenin in intersexual males of Armadillidium vulgare Latreille (oniscoid isopod crustacean): comparison with males and with intact or ovariectomized females

In some natural populations of Armadilidium vulgare, intersex animals are genetic males which are feminized by maternally transmitted symbiotic bacteria. In these intersex males (iM) the fat body synthesizes vitellogenin, although their gonads are testes with hypertrophied--but nonfunctional--androgenic glands. Vitellogenin is present in the hemolymph of males changed experimentally into iM 90 days after inoculation of the feminizing bacteria. During the molting cycle, vitellogenin synthesis in iM varies as in ovariectomized females or in vitellogenic females, with a peak at the stage D1." In A. vulgare, vitellogenin synthesis is a neutral character since it can be observed in a genetic male or in an ovariectomized female; however, it is inhibited by the androgenic hormone. In intersex males, vitellogenin synthesis is the result of their refractoriness to androgenic hormone.     

Ovarian stimulation of juvenile hormone biosynthesis in the viviparous cockroach, Diploptera punctata

A direct radiochemical assay for juvenile hormone (JH) biosynthesis by the corpora allata (CA) showed that the cyclic changes in biosynthesis associated with the gonadotrophic cycle were abolished in the absence of ovaries whether or not the CA were innervated. In ovariectomized animals denervated CA synthesized JH at slightly higher rates than did innervated CA. However, the low rates of JH synthesis in ovariectomized females were sufficient to result in accumulation of vitellogenin in the hemolymph to levels twice those of normal females. Implantation of one ovary 1 week after ovariectomy resulted in a cycle of JH biosynthesis qualitatively similar to that observed during a normal gonadotrophic cycle. Implantation of one ovariole did not result in a detectable cycle of JH biosynthesis whereas normal rates of JH synthesis were observed after implantation of three to six ovarioles. Implantation of four ovaries resulted in a cycle of CA activity more attenuated than that observed in the presence of one ovary. Nonetheless all four ovaries sequestered a normal quantity of vitellin.     

Changes in the sensitivity of adult cockroach corpora allata to a brain allatostatin

There are major changes in the sensitivity of corpora allata from the cockroach Diploptera punctata toward the allatostatic tridecapeptide APSGAQRLYGFGL-amide (ASAL) during the female reproductive cycle, as revealed by measurement of juvenile hormone (JH) biosynthesis in vitro. Glands from recently molted adult females show only 30-40% inhibition at 10 nM ASAL, falling to a minimum of less than 10% on day 5 at the peak of spontaneous JH synthesis in vitro. The decline in JH synthesis observed in post-vitellogenic females is accompanied by a dramatic increase to ca. 90% ASAL sensitivity at 10 nM by day 6. Then sensitivity slowly wanes during subsequent ovulation and pregnancy to the levels typical of previtellogenic and virgin females. Full dose/response studies reveal a second level of response at ca. 1 microM, which resembles the pattern obtained from whole brain extracts. We conclude that physiological sensitivity to ASAL (IC50 ca. 0.1 nM) is correlated with the preparation for choriogenesis, and we suggest that 1000 times higher doses give a cross-reaction with related allatostatic receptor(s) that confer important sensitivity at other development stages.     

Effects of Short-Day Photoperiods and of N-(2,4-Dinitrophenyl)-5-Methoxytryptamine, a Putative Melatonin Antagonist, on Melatonin Synthesis in the Harderian Gland of the Syrian Hamster, Mesocricetus auratus

The Harderian glands of Syrian hamsters contain melatonin and the enzymes N-acetyltransferase (NAT) and hydroxyindole-O-methyltransferase (HIOMT) which synthesize melatonin from serotonin. Because the Harderian glands share this metabolic pathway with the pineal gland, we examined the effects of short-day photoperiods, which stimulate pineal-mediated gonadal regression, and N-(2,4-dinitrophenyl)-5-methoxytryptamine (ML-23), which has been described as a melatonin antagonist, on melatonin synthesis in the Harderian glands of the hamster. Harderian glands of male hamsters kept in short days had reduced NAT activity and melatonin concentration, but HIOMT activity was unchanged from that of long-day controls. In males kept in short days, ML-23 restored melatonin concentrations to levels seen in long days but did not affect the short-day induced reduction in NAT activity. ML-23 had no effect upon NAT or HIOMT activity or melatonin concentration in male hamsters kept on long days. Harderian glands of female hamsters kept on short days had reduced melatonin concentrations, but NAT and HIOMT activities similar to those of long-day controls. ML-23 had no effect on Harderian NAT or HIOMT activities or melatonin concentration in females kept in short days. However, in females kept in long days, ML-23 treatment led to increased NAT activity and decreased melatonin concentrations. We conclude from these results that short-day photoperiods alter some aspects of melatonin synthesis in hamster Harderian glands and that these effects differ in males and females. ML-23 does not usually prevent the effects of short days on Harderian melatonin synthesis, suggesting that it is not a melatonin antagonist in the Syrian hamster.     

Ovaries and regulation of juvenile hormone titer in Acheta domesticus L. (Orthoptera)

A study was performed on females Acheta domesticus to examine the effects of various experimental conditions on the ovarian physiology. Using a radioimmunoassay to determine juvenile hormone (JH) titers as well as in vitro JH biosynthesis, we observed that retention of mature follicles in egg-retaining females, i.e., virgins or mated females not provided an egg-laying substrate, inhibits JH production and consequently oocyte development. Mating in intact as well as ovariectomized females does not affect corpora allata activity. It is only when mating is associated with egg laying that JH biosynthesis and hemolymph titers increased and oocyte development and fecundity are stimulated. Despite lower JH biosynthesis, ovariectomized females present enlarged corpora allata and the levels of JH observed in their hemolymph were intermediate between those of intact egg-laying and virgin females. In intact females, the hemolymph JH titers as well as the JH esterase activities were related to ovarian development. JH esterase activity was very high in ovariectomized animals. Several factors involved in ovarian development of A. domesticus are discussed.     

Primary induction of vitellogenin mRNA in the rooster by 17beta-estradiol.

We have studied the kinetics of vitellogenin mRNA accumulation in rooster liver after a primary injection of 17beta-estradiol. The levels of vitellogenin mRNA have been determined both by hybridization of total cellular RNA to vitellogenin cDNA and by translation of vitellogenin mRNA in a wheat germ cell-free system. The results obtained by both methods of analysis are in good agreement and indicate that vitellogenin mRNA is present in the liver of normal roosters at a level of 0-5 molecules per liver cell and increases in amount during the 3 days following injection of estrogen, reaching a level of almost 6000 molecules per cell at the peak of the response. The level of vitellogenin mRNA declined exponentially during the next 14 days with a half-life of 29 hr, reaching a level of less than 10 molecules per cell at 17 days after injection of the hormone. The levels of vitellogenin mRNA after stimulation with estrogen have been correlated with the in vivo rate of synthesis of the vitellogenin polypeptide. The results indicate that the rate of vitellogenin synthesis is closely correlated with the level of vitellogenin mRNA. On the basis of these findings, we conclude that vitellogenin mRNA does not exist in the liver in an untranslated form after withdrawal from estrogen.     

Response of male corpora allata to ovarian stimulation in the cockroach, Diploptera punctata

In Diploptera punctata, female corpora allata (CA) show a cycle of juvenile hormone (JH) synthesis in response to oocyte development. Whether the smaller male CA can also respond to the ovary was investigated. One or two pairs of male CA were implanted into allatectomized females during the period corresponding to egg growth. Low rates and no cycle of JH synthesis occurred in CA of sham-operated males or in male CA implanted into males or ovariectomized females. On the contrary, male CA, either one or two pairs, implanted into females with ovaries showed a cycle of increase and decrease in JH synthesis similar in pattern to that of female glands implanted into females. However, the peak of JH synthesis for a single pair of male CA occurred 1 day later than the peak for two pairs of male CA or one pair of female CA. Also the maximum rates of synthesis of one or two pairs of male CA were lower than those of female glands. However, rates of JH synthesis per cell and per unit volume of corpus allatum tissue were higher for one pair of male CA than for one pair of female CA. Thus, the intrinsic difference between male and female CA appears to be their size rather than rate of JH synthesis and ability to respond to ovarian stimuli.     

Effects of hypophysectomy on vitellogenesis in the elasmobranch Scyliorhinus canicula L

The effects of total hypophysectomy on vitellogenesis in adult female Scyliorhinus canicula were investigated by injection of ³²P-phosphate 5 days after operation. The rate of plasma vitellogenin formation was not significantly altered by the operation, but removal of vitellogenin from the plasma was delayed relative to controls. Similar investigation 3 days after partial hypophysectomy showed that this effect was caused by removal of the intracranial lobes of the pituitary (the neuro-intermediate/median/rostral lobe complex) but not by removal of the ventral lobe. None of these operative procedures was found to produce a significant effect on the rate of yolk granule synthesis. Consideration is given to the possibility that the intracranial pars distalis of the pituitary secretes a hormone which stimulates the uptake of vitellogenin by growing ovarian follicles.     

Intrinsic differences in juvenile hormone synthetic ability between corpora allata of males and females of the cockroach Diploptera punctata

To study the basis for differences in juvenile hormone (JH) synthesis exhibited by corpora allata (CA) of males and females of the cockroach Diploptera punctata, the activity of male and female CA is compared after implantation into allatectomized adult females. Implanted male CA are able to support complete oocyte development, but at a reduced rate. Measurement of juvenile hormone biosynthesis by implanted CA with an in vitro radiochemical assay shows that implanted male CA synthesize JH at much lower rates than those of implanted female CA. The fact that male CA are smaller than female CA accounts in part for their lesser synthetic ability.     

Roles of ecdysteroid and juvenile hormone in vitellogenesis in an endoparasitic wasp, Pteromalus puparum (Hymenoptera: Pteromalidae)

To elucidate the endocrine regulation of vitellogenesis in an endoparastic wasp (Pteromalus puparum), the titers of ecdysteroid and juvenile hormone (JH) from the whole bodies are measured using the method of radioimmunoassay and GC-MS, and compared with the levels of vitellogenin (Vg) mRNA in the fat bodies, hemolymph Vg and ovarian vitellin (Vt), respectively. The results show that the ecdysteroid titer and fat body Vg mRNA level have a similar dynamics tendency, and the peak titer is at adult eclosion. The titer of JH III and ovarian Vt also have a similar dynamics tendency, and the peak titer is at 48 h after eclosion. The profiles of hemolymph Vg, Vg mRNA in fat bodies and ovarian Vt, are also measured in the wasps after treated with different amounts of 20-hydroxyecdysone (20HE) or JH III in female pupa and adults. The results show that 20HE stimulates Vg synthesis in the fat bodies and its release into the hemolymph, and that JH III only accelerates Vg sequestration in the oocytes. Decapitation, which is believed to terminate synthesis of JH in insects, can not inhibit vitellogenesis and oocyte maturation in P. puparum. Furthermore, Vg gene is expressed with a lower titer of JH and depressed by a higher titer of JH III. These studies suggest that ecdysteroids play a role in Vg synthesis and believed to be the dominant hormones in regulation of vitellogenesis in P. puparum, and JHs are not the essential factors to female reproduction in this wasp.     

Juvenile hormone synthesis as related to egg development in neotenic reproductives of the termite Reticulitermes flavipes, with observations on urates in the fat body

The relationship between juvenile hormone (JH) synthesis and egg development, which is well documented in cockroaches, is much less studied in their close relatives, the termites. In this study of neotenic reproductives of the subterranean termite Reticulitermes flavipes, in vitro rates of juvenile hormone (JH) synthesis by corpora allata (CA) are related to vitellogenic egg development and the size of CA. The first study compared brachypterous and apterous neotenics in their first cycle of egg development and a second study compared physogastric and non-physogastric brachypterous and apterous neotenics. In both studies, rates of JH synthesis correlated with the size of CA as indicated by their length. Unlike the cockroach in which all basal oocytes are in the same stage of development, those in termites are in various stages. In brachypterous and apterous in the first cycle of egg development, CA with high rates of JH synthesis were from females with early vitellogenic basal oocytes, whereas CA with low rates of JH synthesis were from females with either pre-vitellogenic or mature basal oocytes. This pattern of JH synthesis is similar to the cycle of JH synthesis correlated with oocyte development in several cockroach species. In later oocyte maturations, CA from physogastric apterous females with ovaries containing mature, as well as growing oocytes, showed a wide range of JH production; the CA with the highest rates of JH synthesis were from females with the highest proportion of early vitellogenic oocytes suggesting that both mature and early vitellogenic oocytes interact to regulate JH synthesis. Rates of JH synthesis were related to the number of vitellogenic ovarioles. Physogastric brachypterous neotenics, compared to the other classes of neotenic females, had CA with 2- to 4-fold higher rates of JH synthesis and ovaries with 2.5- to 8-fold greater number of vitellogenic ovarioles. However, both physogastric brachypterous and apterous neotenics had more vitellogenic basal oocytes and less urate in their fat bodies than the respective non-physogastric neotenics. These results demonstrate the similarities and differences between the classes of neotenic termites and between reproductive females in cockroaches and termites.     

Sexual mimicry regulates the attractiveness of mated Drosophila melanogaster females.

During mating, male Drosophila melanogaster transfer to the female's cuticle a compound (7-tricosene) that is almost absent from virgin females but is the major hydrocarbon component of the male's cuticle. During the first 3 hr after mating, the amount of 7-tricosene on a female decreases sharply but remains significantly above virgin levels. By 6 hr after mating, female synthesis of 7-tricosene has increased, and females release it when they are exposed to courting males. Transfer of 7-tricosene to immature virgin females by courting males significantly decreases their attractiveness, so 7-tricosene has demonstrable antiaphrodisiac properties. Thus, mated D. melanogaster females appear to mimic males by releasing, during courtship, an antiasphrodisiac pheromone that is almost absent from virgin females but is the most prominent hydrocarbon of the male cuticle.     

Vitellogenin synthesis in andrectomized males of the terrestrial isopod, Armadillidium vulgare (malacostracan Crustacea)

When adult females of Armadillidium vulgare were ovariectomized, the fat body continued to synthesize vitellogenin. On the other hand, females transplanted with androgenic glands decreased the synthetic activity for vitellogenin in their fat body. In order to elucidate effect of the androgenic hormone for vitellogenin synthesis, the occurrence of vitellogenin was studied with andrectomized males. Vitellogenin was estimated, using rocket immunoelectrophoresis. Vitellogenin synthesis in the fat body was analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis and fluorography. After andrectomy, males ceased elongation of the endopods (copulatory organs) and then vitellogenin was present in their hemolymph. Their vitellogenin titer continued to rise until it reached approximately three times higher than that of normal females. The accumulation level of vitellogenin was comparable with that of ovariectomized females. However, the activity of vitellogenin synthesis was at a low level in the fat body culture of andrectomized males, similar to ovariectomized females. These results indicate that andrectomized males are capable of vitellogenin synthesis, so one of the effects of the androgenic hormone is to inhibit vitellogenin synthesis. In A. vulgare, ovarian factors may not be involved in the induction of vitellogenin synthesis.     

Juvenile hormones (JHs) and completion of oöcyte development in the African migratory locust: A comparative and quantitative study

The effect of juvenile hormones (JHs) I and III on induction and completion of oöcyte development in allatectomized adult Locusta migratoria migratorioides females was studied. Whenever possible, oviposition rate served as a parameter, though, necessarily, oöcyte length was employed when no laying occurred. In the latter instance, oöcytes were usually measured twice, at laparotomy (special operation of the living female) and later at dissection. Normal (unoperated), allatectomized, allatectomized and later corpora allata (CA)-implanted females, as well as allatectomized females receiving solvents without hormone, constituted the controls. Allatectomy prevented oöcyte development, but reimplantation of CA led to its completion (laying). Injection or topical application of solvent(s) alone did not induce oöcyte development in allatectomized females. Topical application of JHI in methanol induced small, though distinct, vitellogenetic growth of the oöcytes. A more marked effect was obtained with JHI topically applied in olive oil. Injection of JHI greatly improved the effect, and only this method led to completion of oöcyte development. Hormone concentration in olive oil between 0.075 and 0.5% ($\text{w}\text{v}$), single or repeated (up to four) injections, did not influence oviposition rate for a 40-μg cumulative dose of JHI, though duration of laying was affected. Increasing cumulative doses of JHI, or JHIII, increased oviposition rate, furnishing well-defined dose-response curves. ED₅₀ (effective dose 50%, defined as 0.5 oviposition rate, that is, number of pods laid is equal to half the number of females) was about 30 μg per female for JHI and about 44 μg per female for JHIII. Thus, JHI was about 1.4–1.5 times more efficacious than JHIII. Ten micrograms of JHI did not induce completion of oöcyte development; 60 μg did so more than once in a portion of the females. Surprisingly, dosage and cumulative dose did not affect the number of eggs per pod, which always remained considerably lower than in normal (unoperated) controls. Pods laid by allatectomized and JH-injected females were viable, hatched reasonably, and the progeny achieved normal adult stage and sexual maturation. Injected JHI restored the secretory functioning of the oviduct. Unreliability of oöcyte length for assaying JH in adult female locusts, mode of JH administration, lack of difference in the results for single and repeated injections (of the same cumulative dose), and the crucial effect of the cumulative dose are discussed. Effective doses are considered as unphysiologically high, and some hypotheses are forwarded in explanation. The lack of effect of the cumulative dose on number of eggs per pod is also discussed and related to nutritional and/or metabolic factors, especially female-specific protein (=vitellogenin) synthesis.     

Properties of a strain of free-living nematode, Rhabditidae sp.: life cycle and age-related mortality

Some properties, especially the life cycle and the temperature-dependency of age-related mortality, of a newly isolated free-living nematode have been investigated. The nematode was identified as a member of the family Rhabditidae, but the genus has not yet been identified. The nematode is bisexual and the male to female ratio was found to be 1 : 15. In all experiments animals were cultured with Escherichia coli cells as a food source. At 20°C, eggs hatched to larvae after about 24 hours and the eggs of the next generation appeared in a population about 5 days after being laid. The longevity of the nematode was greatly influenced by the temperature. The average life span observed for virgin females at 20°C was about 95 days and that at 35°C was 30 days. The life span of the females which had laid eggs was shorter than that of virgin females. Virgin males were also found to have a shorter average life span than virgin females. One female lays about 100 eggs during its life span. It was shown that one third of 100 days old virgin females could mate with males and produce about 100 eggs per female with almost complete hatchability. These results indicate that this particular nematode is a useful animal for the study of aging, like other free-living nematodes currently being used in aging research.     

Mutations in insulin signaling pathway alter juvenile hormone synthesis in Drosophila melanogaster

Juvenile hormone (JH) is a key endocrine regulator of insect metamorphosis, reproduction, and aging. The synthesis of JH is regulated by neuropeptides and biogenic amines, but the molecular and cellular basis of this control remains largely unknown. Genetic analysis of JH synthesis in Drosophila melanogaster mutant for insulin signaling may provide new and powerful insights. Mutants of the insulin receptor (InR) are slow to develop, small, infertile, and long-lived. We previously reported that mutants of InR had reduced JH synthesis as young adults, and that normal longevity and vitellogenesis were restored by topical application of a JH analog [Science 292 (2001) 107]. Here, we describe the 10-day adult age course of JH synthesis from isolated corpus allatum (CA) of InR and of chico, the insulin receptor substrate homolog. JH synthesis increased in wildtype flies to a maximum of 30fmol/gland/h at day 10. In contrast, homozygous InR mutants produced no more than 3 fmol/gland/h JH within the first 5 days, and only 7 fmol/gland/h at day 10. InR mutation disproportionately reduced the synthesis of JH III-bisepoxide, the major JH subtype of the fly. Mutation of chico also reduces body size and extends longevity [Science 292 (2001) 104; Aging Cell 1 (2002a) 75]. Both homozygous and heterozygous chico genotypes reduced JH synthesis, but only to 47 and 67%, respectively, of wildtype and without influencing the ratio of JH subtypes. Because JH synthetic rate does not correlate with the size of CA, it is not likely that insulin signaling mediates JH by impeding endocrine tissue development. Alternatively, we find allatotropin-positive axons to be abundant in the adult brain and in the corpora cardiaca-corpus allatum complex but these neurons are less immunoreactive in the InR mutant genotype, suggesting that insulin signaling may affect JH synthesis through control of JH regulatory neuropeptides.     

Neuroendocrine and juvenile hormone effects on fat body protein synthesis during the reproductive cycle in female Blaberus discoidalis cockroaches

Ovarian protein content and fat body protein synthesis were measured during the first gonotrophic cycle in virgin female Blaberus discoidalis cockroaches. Protein synthesis was measured for in vitro fat bodies from animals treated with combinations of a juvenile hormone analog (JHA = methoprene) and corpora cardiaca (CC) extracts. Ovarian protein content began to increase on Day 5 of adult life and reached its maximum at Days 20-22. Synthesis of proteins secreted by the in vitro fat body increased by 12-fold between emergence and its maximum on Day 18, then declined to nearly its original level by Day 33. Synthesis of nonsecreted, fat body proteins increased by 4-fold between emergence and a maximum on Day 21, then declined. CC extracts and JHA were administered to decapitated females to determine their regulative effects on fat body protein synthesis. The synthesis by the fat body of nonsecreted proteins was increased by both JHA and CC extracts. In contrast, synthesis of secreted proteins increased only in the presence of JHA. CC extracts, alone, had no effects on the synthesis of secreted proteins, but administration of CC extracts in combination with JHA increased the synthesis of the secreted proteins by 55% above that observed with JHA alone. SDS-PAGE of proteins secreted into the medium by the in vitro fat body demonstrated that JHA stimulated the synthesis of specific polypeptides, whereas CC extracts did not affect the synthesis of specific-secreted polypeptides. These results suggest that JH regulates specific protein synthesis by the fat body of B. discoidalis; neurohormones elevate the general capacity of the fat body for protein synthesis and amplify the specific effects of JH.