Limulus lateral eyes shed and renew a portion of their photosensitive membrane (rhabdom) daily. Shedding, in many species including Limulus, is regulated by complex interactions between circadian rhythms and light. Little is known about how circadian clocks and photoreceptors communicate to regulate shedding. Limulus photoreceptors do not contain an endogenous circadian oscillator, but rely upon efferent outflow from a central clock for circadian timing. To investigate whether the putative efferent neurotransmitter octopamine (OA) communicates circadian rhythms that prime the lateral eye for transient rhabdom shedding, we decoupled photoreceptors from the clock by transecting the lateral optic nerve (contains the retinal efferent fibers). Overnight (6 h) intraretinal injections of 40 microM OA restored transient shedding to lateral eyes with transected nerves to levels comparable to those of intact internal control eyes. To determine whether OA acts alone in communicating circadian rhythms that prime the lateral eye for transient shedding, we "primed" eyes with intact nerves for transient shedding with exogenous OA during subjective day. In nature, lateral eyes shed their rhabdoms only once a day at dawn following overnight efferent priming. Eyes in animals placed in darkness during subjective day, when the retinal efferents are quiescent, and injected for 6 h with 40 microM OA shed their rhabdoms in response to a second introduction to light. Untreated control eyes of the same animals did not. The same results were observed in vitro in lateral eyes treated similarly. Octopamine is the only efferent neurotransmitter/messenger required to make lateral eyes competent for transient shedding. Phentolamine, an OA receptor antagonist, reduced the number of photoreceptors primed for transient shedding and the amount of rhabdom shed in those photoreceptors suggesting that OA acts via a specific OA receptor.
The anonymous author of A Spy on Mother Midnight (1748) applies libertine philosophy to commonplace elements of eighteenth-century amatory and erotic fiction, producing a story that offers omnisexual thrills and unmistakable homoerotic interest. This manipulation suggests that the boundaries of pornographic appeal in the period may have been more flexible than scholars have generally believed. At a time when public discourse on “sodomites” and “mollies” was almost uniformly negative, Mother Midnight's libertinism creates homoerotic allure without the intratextual or actual punishment expected in connection with both pornography and homosexuality. Though the tale embraces the amorality of the aristocratic libertines, it blurs social boundaries as well as gender boundaries, using class voyeurism to enable sexual voyeurism. With a letter from a man to his male friend as its framing device, Mother Midnight dwells on the erotic appeal and sexual usefulness of cross-dressing while allowing its readers, standing in for the letter’s recipient, to partake of the transgressive adventures from a safe distance. Because its homoerotic content stays just under the radar, A Spy on Mother Midnight need not excuse itself with homophobic language. As the protagonist disguises himself to gain entrance to a lying-in, A Spy on Mother Midnight disguises its homoerotic sympathies, hiding them, so to speak, in plain sight for interested readers to discover.
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