Effects of Odorants on Pigment Aggregation and cAMP in Fish Melanophores

Odor perception within olfactory neuroepithelium and pigment translocation within melanophores both seem to rely on a cAMP-based second messenger system. From studies on cultured frog melanophores, Lerner et al. (Proc. Natl. Acad. Sci. USA 85:261-264, 1988) suggested that some aspect of odor perception may be mediated by a nonspecific mechanism whose signal is transduced by a cAMP-based second messenger system. In the present study, odorants (β-ionone, benzylaldehyde, cineole, cinnamaldehyde, and octanol), which previously have been shown to stimulate formation of cAMP in the olfactory neuroepithelium, were investigated for possible pigment dispersing and cAMP-increasing effects. Pretreatment of fish melanophores with the adenylate cyclase activator forskolin (1 μM) resulted in an approximately 300% increase in cAMP and an almost complete blockage of noradrenaline-induced pigment aggregation. However, none of the tested odorants were able to increase the cAMP level and only cinnaldehyde and β-ionone were found to have any pigment dispersing activity.     

Rapid isolation of anopheline mosquito eye-colour mutants, based on larval colour change

Abstract. A method is presented for the rapid isolation of eye-colour mutants in anopheline mosquitoes based on their inability to undergo a background-stimulated morphological colour change. For application of this method, larval mosquitoes, whose grandfathers had been mutagenized, were reared in black containers and examined with the naked eye en masse during the third or fourth instar. The vast majority of larvae became dark-coloured; however, rare exceptional pale larvae were observed and examined individually microscopically. Approximately half of the pale types examined were eye-colour mutants. By this method, seven sex-linked mutations in the mosquito Anopheles gambiae s.s. were easily isolated. Additional existing anopheline eye-colour mutants in An. gambiae and An. stephensi were tested and were found to be unable to undergo colour change. Several applications of this simple technique are suggested.     

Mate-locating strategies are related to relative body length and wing colour in the speckled wood butterfly Pararge aegeria

1. The mate-locating strategies of Pararge aegeria (L.) males were studied in relation to adult morphology (dorsal wing colour, forewing length, body length and forewing length : body length ratio) and generation.
2. Males locate females either by perching and defending territories, or by patrolling. Individuals were more consistent in their mating strategies than expected by chance.
3. Forewing length : body length ratio was positively correlated with thorax mass : body mass; relatively short-bodied males had relatively heavy thoraxes. Therefore, forewing length : body length ratio was an index of mass allocation.
4. Perching males had higher forewing length : body length ratios and were paler than patrolling males.
5. The higher forewing length : body length ratio was due to the differences in body length and not wing length. Perchers had shorter bodies than patrollers.