The brain and subesophageal ganglion (BR-SG) of the commercial silk worm, Bombyx mori, were stained immunohistochemically at the larval stage for circadian clock neurons with antibodies against Doubletime (DBT) of B. mori and Period (PER) of Periplaneta americana. The BR-SGs were also stained with antisera against [Arg7]-corazonin, which has been known to be present in B. mori and co-localized with PER in Manduca sexta, and against [His7]-corazonin, a homolog identified in other species. From co-localization of [Arg7]-corazonin and PER-like reactivities in the pars lateralis, [Arg7]-corazonin is suspected to be a downstream regulator of the circadian clock in M. sexta. DBT- and corazonin-like immunohistochemical reactivities were found in both the neurosecretory cells of the pars intercerebralis (PIC) and pars lateralis (PL) in B. mori. Small numbers of neurons shared both reactivities against anti-DBT and anti-corazonin. The majority of the immunopositive cells were common to both corazonins, but some cells were unique in expressing either reactivity against [His7]-corazonin or [Arg7]-corazonin only. The results suggest that there is a diversity in the clock output pathway among lepidopterans and that [His7]-corazonin may be present in B. mori, as well as [Arg7]-corazonin, although the former has not been chemically identified in this species. Corazonin may be a downstream regulator of circadian clocks in B. mori because of the co-localization of [His7]-corazonin at PIC and [Arg7]-corazonin at PL with anti-DBT.
A short-winged morph, whose occurrence is controlled by a simple recessive Mendelian unit, was recently discovered in Locusta migratoria. The existence of trade-offs between flight capability associated with wing length and other fitness-related traits are often documented for insects. The present study investigated the evolutionary significance of the short-winged and long-winged morphs of this locust using two laboratory strains showing wing dimorphism. The life-history traits examined included nymphal development, adult body weight, percentage adult survival, age at first reproduction, egg production and hatchling body weight. The results indicate that there are no consistent morph-specific differences in any of these traits. Of the several possibilities considered, the most likely is that the short-winged morph of this locust is an aberration or represents an initial stage in the evolution of this species., Yudai Nishide, Seiji Tanaka., and Obsahuje seznam literatury