RESUMEN

Proteolytic enzyme biosynthesis in the midgut of the 4th instar larva of Heliothis virescens is cyclical. Protease activity increases immediately after the molt from the 3rd to the 4th instar larvae and declines just before the molt into the 5th instar. Characterization of the midgut proteases using soybean tryspin inhibitor (SBTI) Bowman Birk Inhibitor (BBI) 4-(2-aminoethyl)benzensulfonylfluoride (AEBSF) and N-tosyl-L-phenylalanine chloromethylketone (TPCK) indicate that protease activity is mostly trypsinlike (80%) with a small amount of chymotrypsinlike activity (20%). Injections of late 3rd and 4th instar larval hemolymph into H. virescens larvae inhibited tryspin biosynthesis in the larval midgut. Similar results were obtained when highly purified 4th instar larval hemolymph that crossreacted with Aea-TMOF antisurm using ELISA was injected into 2nd instar larvae. Injections of Aea-TMOF and its analogues into 2nd instar, and Aea-TMOF alone into 4th instar larvae stopped trypsin biosynthesis 24 and 48 h after the injections, respectively. Injections of 4th instar H. virescens larval hemolymph into female Aedes aegypti that took a blood meal stopped trypsin biosynthesis and egg development. These results show that the biosynthesis of trypsin-like enzymes in the midgut of a lepidoptera is modulated with a hemolymph circulating TMOF-like factor that is closely related to Aea-TMOF. Arch.

Asunto(s)

RESUMEN

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.

RESUMEN

Brain-retrocerebral complexes of female crickets, Gryllus bimaculatus and Acheta domesticus, treated with antibody to allatostatin-1 from a cockroach, Diploptera punctata, show extensive immunoreactivity. The results suggest that allostatins or allatostatin-like molecules are produced in neurosecretory cells of the brain and are delivered to the corpora allata through nervous connections and/or via haemolymph. Radiochemical measurements of juvenile hormone III biosynthesis by isolated corpora cardiaca-corpora allata complexes from adult G. bimaculatus have been used to demonstrate an in vitro sensitivity of these glands to allatostatin-1 from D. punctata. Allatostatin-1 is a relatively potent inhibitor of juvenile hormone III biosynthesis in corpora allata of both young adult females and males. In glands taken from 3-day virgin females, 50% inhibition of hormone biosynthesis is reached at ca. 3 nmol.l-1 allatostatin-1. The inhibitory action of allatostatin-1 is rapid, dose-dependent and reversible. Addition of 200 mumol.l-1 farnesol to the incubation medium prevents inhibition of juvenile hormone III biosynthesis by allatostatin-1. Juvenile hormone III biosynthesis by isolated corpora allata of 3-day female house crickets, A. domesticus, is also susceptible to inhibition by 1 mumol.l-1 allatostatin-1.

Asunto(s)

RESUMEN

To the authors' knowledge, colonic hemorrhage from anomalous ventral aortic mesenteric arteries has not been described previously. They report a case in which a middle mesenteric artery with unusual vascular distribution supplied a splenic flexure hemorrhage in a 62-year-old man. Although this is a rare anomaly, a thorough understanding of the middle mesenteric artery may have important diagnostic and therapeutic implications.

Asunto(s)