Identification,characterization, and developmental profile of a high molecular weight,juvenile hormone-binding protein in the hemolymph of the migratory grasshopper,Melanoplus sanguinipes

In the hemolymph of Melanoplus sanguinipes, a high molecular weight juvenile hormone binding protein (JHBP) was identified by photoaffinity labelling and found to have a M_r of 480,000. The JHBP, purified using native gel electrophoresis followed by electroelution, has an equilibrium dissociation constant for JH III of 2.1 nM and preferentially binds JH III over JH I. Antibody raised against JHBP recognized only the 480,000 band. Under denaturing conditions the native JHBP gave a single band with a M_r 78,000. The antibody against native JHBP recognized only the 78,000 protein in SDS-treated hemolymph samples, indicating that JHBP is a hexamer in this species. The concentration of JHBP fluctuates in both the sexes during nymphal and adult development in parallel with total protein content of hemolymph. © 1995 Wiley-Liss, Inc.     

Hormonal control of uric acid storage in the fat body during last-larval instar of Manduca sexta

In the last-larval instar of the tobacco hornworm, Manduca sexta, a switch from excretion of uric acid to storage in the fat body occurs during transition from the feeding to the wandering stage. Neuroendocrine control of this change from excretion to storage was demonstrated by neck-ligation experiments with synchronously reared larvae. Results indicate that a neurohormone is released from the head 24–30 hr before the initiation of wandering and coincident with the first release of ecdysone that initiates metamorphosis. Direct involvement of the moulting hormone was shown by the effects of multiple injections of 20-hydroxyecdysone into the abdomen of larvae that had been ligated before the release of hormone. Urate levels in the fat body were 20- to 100-fold higher from hormone-injected larvae as from saline inject controls. Topically applied juvenile hormone or methoprene reversed the 20-hydroxyecdysone-induced storage of urate. Increased levels of uric acid in the haemolymph during pupal development result from the presence of juvenile hormone, and the abrupt decrease in uric acid concentration in the haemolymph just prior to pupal ecdysis results from a decreased titre of juvenile hormone. Applications of methoprene prevented the decrease in uric acid levels in the haemolymph.     

Improved assay conditions for measurement of corpus allatum activity in vitro in the adult Colorado potato beetle, Leptinotarsa decemlineata

Assay conditions for the short-term, radiochemical, in vitro determination of the spontaneous rate of juvenile biosynthesis by isolated corpora allata from Leptinotarsa decemlineata have been further improved, permitting the measurement of juvenile hormone biosynthesis by individual pairs of corpora allata. The final incubation product has been identified as juvenile hormone III with the aid of High-performance liquid chromatography (HPLC) and juvenile hormone esterase degradation. Using the new assay conditions, the activities of adult corpora allata during maturation were found to be significantly higher in reproductive, long-day animals than in pre-diapause, short-day beetles. During diapause no activity was detectable, whereas corpora allata from post-diapause beetles were reactivated totally after 5 days. Simultaneous determination of the in vitro rates of juvenile hormone biosynthesis and corpus allatum volumes revealed no clear correlation although the results suggest that the volume may be indicative of the maximal capacity for juvenile hormone production. Corpora allata from a population of beetles did not display any synchronous diurnal rhythmicity.     

Circadian placebo and ACTH effects on urinary cortisol in arthritics

The effect of placebo and ACTH-1-17 (Synchrodyn®, Hoechst) upon urinary free cortisol was examined at 5 different circadian stages on 10 men with Steinbrocker Stage II–III rheumatoid arthritis. A mean cosinor analysis of urinary cortisol data from the subjects prior to treatment with either ACTH or placebo revealed a statistically highly-significant rhythm. A circadian variation in a response of urinary free cortisol to a placebo was also seen. Moreover, the response of the midline-estimating statistic of rhythm (rhythm-adjusted circadian average) of urinary free cortisol to ACTH-1-17 by patients with rheumatoid arthritis is circadian rhythmic. This reactivity rhythm is out of phase with the spontaneous rhythm in urinary cortisol acrophases—in the tests limited thus far to midsummer. The further assessment of the circadian component in the context of broader interactions by rhythms with other frequencies in various conditions in health and disease is warranted by the demonstration of rhythms here presented for men with rheumatoid arthritis.     

Protective Effects of Human Recombinant Mnsod in Adjuvant Arthritis and Bleomycin-Induced Lung Fibrosis

We have previously shown that human recombinant methionyl manganese superoxide dismutase (MnSOD) is more efficient than CuZnSOD as an anti-inflammatory agent in a model of acute inflammation (Carrageenan-induced pau edema). This effect was attributed to the prolonged half-life of MnSOD in blood (t_1/2 = 6 h vs. 10 min. respectively). In the present study, the two enzymes were compared in terms of their effectiveness in two systems: (I) Adjuvant-induced arthritis in rats, which is considered to be a model for the chronic situation of rheumatoid arthritis and (2) Bleomycin-induced lung fibrosis. which is a chronic situation believed to be mediated by oxygen free radicals.

Rats inflicted with adjuvant arthritis were treated during the period of maximal joint swelling (Days 15-21 after adjuvant injection) with MnSOD or CuZnSOD (12 to 50mg/kg, i.p. daily). MnSOD administration resulted in a 50-75% reduction of paw swelling, as well as inhibition of the elevation of serum globulins. A similar treatment with CuZnSOD gave merely marginal effects.

In the second system, lung fibrosis was induced in rats by intratracheal administration of bleomycin. MnSOD (50mg/kg, s.c.), administered 2 h before and then 2 and 4 days after bleomycin, markedly inhibited lung fibrosis, as evident from lung weight and collagen content measured by the 3rd week. By contrast, CuZnSOD administration did not give a significant effect. The results indicate that MnSOD is superior to CuZnSOD in the treatment of chronic inflammatory processes. In addition, they lend further support to the involvement of oxygen free radicals in bleomycin toxicity.     

Ixodes dammini: Induced skin lesions in guinea pigs and rabbits compared to erythema chronicum migrans in patients with lyme arthritis

Erythematous skin lesions occurred in rabbits 2 days after being fed upon by larvae or nymphs of the tick, Ixodes dammini. Similar lesions occurred in guinea pigs 7 days after a primary infestation with either larvae or nymphs. Host resistance to secondary feeding by larvae was demonstrated in guinea pigs and rabbits. Host resistance to secondary feeding by nymphs was seen in guinea pigs, but not in rabbits. Guinea pigs developed resistance to nymphs after being previously fed upon twice by larvae. All skin lesions in resistant guinea pigs contained large accumulations of basophils (49–76% of cells) with smaller (20–33%), but significant, numbers of eosinophils. These responses were characteristic of strong cutaneous basophil hypersensitivity reactions. Primary and secondary lesions in rabbits fed upon by larvae contained mostly mononuclear cells (46–52%) and moderate numbers (16–30%) of basophils and eosinophils. Primary and secondary lesions in rabbits fed upon by nymphs had few (3–11%) basophils and eosinophils and were dominated by mononuclear cells (73–86%). Thus, acquired resistance in guinea pigs and rabbits was associated with cutaneous basophil and eosinophil responses and the lack of resistance of rabbits to nymphs was associated with erythematous lesions dominated by mononuclear cells. The mononuclear nature of rabbit lesions induced by nymphal feeding was similar to that seen in erythema chronicum migrans in Lyme arthritis patients who are thought to have been fed upon by I. dammini nymphs. This study confirms the cutaneous basophil hypersensitivity characteristics of lesions in guinea pigs resistant to ticks and demonstrates a relationship between the mononuclear cell response of rabbits to nymphal I. dammini and the cellular response seen in patients with erythema chronicum migrans and Lyme arthritis.     

Endocrine influence upon the development of vitellogenic competency in Oncopeltus fasciatus

Immunoelectrophoretic analysis of the blood of precocious adult females of Oncopeltus demonstrated the presence of the A form of vitellogenin but no detectable AB form, the form present in mature adult-female haemolymph. Although the appearance of the AB form could be induced by topical treatment of precocious adult females with juvenile hormone, no yolk deposition was induced in these females. Histological examination revealed that the ovaries of precocious adult females reached only a previtellogenic stage of development with or without treatment with juvenile hormone. Topical treatment of normal larvae and adults with the hormone demonstrated that vitellogenin synthesis could not be induced with juvenile hormone treatment alone until after adult emergence. Since the precocious adult females are chronologically younger than normal last-stage larval instars, we suggest that a transition period during which juvenile hormone is absent (i.e. the precocious moult in treated animals; the final moult in control animals) must occur before some tissue of the precocious or normal adult females, presumably the fat body, becomes competent to respond to further exposure to the hormone by making the AB form of vitellogenin. The ovary requires a similar transition period prior to becoming capable of depositing vitellogenin; however, the times when the fat body and the ovary become competent to respond to the transition period differ.     

Effects of methoprene and juvenile hormone on larval ecdysis,emergence, and metamorphosis of the endoparasitic wasp, Apanteles congregatus

Topical application of juvenile hormone I and III or the hormone analogue methoprene to parasitized Manduca sexta larvae inhibited subsequent emergence of the endoparasitic wasp Apanteles congregatus. Methoprene treatment inhibited wasp emergence in a dose-dependent manner, causing either a delay or total inhibition of emergence. These results were interpreted as reflecting inhibitory effects of juvenile hormone on the second-larval ecdysis of the parasitoid that normally occurs during emergence from the host larva. Parasitoid ecdysis was disrupted even when methoprene was applied to host larvae a few hours prior to the normal expected time of emergence. A correlation between the number of emerging parasitoids and the timing of emergence was seen in methoprene-treated hosts, and few parasitoids emerged after day 9 of the host's fifth-instar. Our findings suggest that the suppression of emergence by juvenile hormone analogues noted in previous studies may be due to a similar inhibitory effect on parasitoid ecdysis. We also observed that parasitoids emerging from hosts treated with a low dose of methoprene (1 μg) later pupated normally but then formed nonviable pupal-adult intermediates. Thus use of this insect growth regulator must be undertaken carefully to prevent possible adverse effects on natural parasitoid populations.     

The hormonal control of accessory reproductive gland development in female Schistocerca gregaria

Allatectomy of adult female Schistocerca gregaria prevents the normal development of the accessory reproductive glands and no secretion is produced. Development of the glands can be restored by the administration of synthetic juvenile hormone and the response is dose-dependent. A continuous supply of hormone is required for maintenance of secretory activity. In the normal developmental sequence the total protein content of the glands remains constant until the time at which vitellogenesis occurs in the terminal oöcytes. As maturation proceeds there is a linear increase in protein content of the glands. The initial increase occurs as a result of cellular changes in the glands and is then followed by an increase due to an accumulation of secretion in the lumina.