Staining in the brain of Pachymorpha sexguttata mediated by an antibody against a Drosophila clock-gene product: labeling of cells with possible importance for the beetle's circadian rhythms

Abstract

Central nervous system ganglia within the head of the beetle Pachymorpha sexguttata were labeled using an antibody that recognizes an evolutionarily conserved region of the period (per) gene product of Drosophila melanogaster. per and the protein it encodes (PER) are believed to play a central role in the generation of endogenous circadian rhythms in flies; therefore anti-PER-mediated immunoreactivity may help to uncover cellular components of the circadian clock system in that insect and in others. In the beetle, application of this antibody led to the staining of a distinct set of neurons located in the optic lobes and the central brain, plus small numbers of putative glial cells in the optic lobes. Neuronal perikarya (including their nuclei in a few cases), the axons, and terminal regions of the neurons were stained. The network formed by these labeled cells and processes are candidates for the neuronal basis of the beetle's circadian clock system: the pacemaker region situated next to the medulla neuropil, its connection to the apparent site of Zeitgeber input, and putative efferent pathways projecting to control centers of various effector systems. Anti-PER-mediated labeling and that resulting from application to beetle specimens of an antiserum against pigment-dispersing hormone (PDH) were compared; in the Drosophila brain all "PDH cells" express the per gene as well. In the beetle, however, the set of "PER cells" and PDH ones is at least in part nonoverlapping. The hypothesis that neurons stained by application of anti-PER participate in the control of the beetle's circadian rhythms is discussed in the context of previous electrophysiological and immunohistochemical studies. Also considered are analogies to, and differences from, labeling of the PER protein in fruit flies and PER-like immunoreactivity in other animals.

Circadian Rhythm Gene Regulation in the Housefly Musca domestica

“…While it can be argued that in some of these studies perhaps the antigenicity did not reflect PER in these insects, or that PER does indeed enter the nucleus at low undetectable levels to engage the negative feedback loop, it is odd that PER antigenicity, whether cycling in the firebrat (Zavodska et al 2003a) or not in the hawkmoth (Wise et al 2002) or the beetle (Frisch et al 1996), or ''not known'' in a variety of other insects (Zavodska et al 2003b), does not usually appear to be nuclear. In fact, on the basis of our initial results with Musca, we might have been tempted to add the housefly to the list of species with ''noncanonical'' patterns of PER regulation.…”

“…In other insect orders, PDF does not colocalize with PER or TIM antigens (Zavodska et al 2003b), although some colocalization of PER and PDF may be present in the beetle Pachymorpha sexguttata (Frisch et al 1996). It therefore may be that the Diptera compared with these other insects have a fundamental difference in this aspect of clock neuronal biology.…”

Roles of PER immunoreactive neurons in circadian rhythms and photoperiodism in the blow fly, Protophormia terraenovae

“…Although in D. melanogaster circadian clock genes and neurons are well known, photoperiodic responses in this species are very shallow and difficult to assay. Clock-gene-expressing neurons or their protein-immunoreactive neurons have been examined in many species (Frisch et al, 1996;Sauman and Reppert, 1996;Závodská et al, 2005;Codd et al, 2007); however, their roles in behavioural rhythms or photoperiodism have not been identified. Only in the hawk moth Manduca sexta, has the loss of photoperiodic control of pupal diapause been shown after ablation of per-expressing neurons (Wise et al, 2002;Shiga et al, 2003).…”

Nonvisual Photoreceptors in Arthropods with Emphasis on Their Putative Role as Receptors of Natural Zeitgeber Stimuli

“…In beetles, these terminals might at least partly originate from neurons innervating the accessory medulla, as could be shown by immunostaining with an antibody raised against the Drosophila Per protein [ Fig. 1(E)] (Fleissner et al, 1993a;Frisch et al, 1996). In cockroaches, efferent innervation from the MEacc was also made possible; immunostaining with antiGaq antibodies clearly showed tiny accessory LAs as in beetles within the first optic chiasm (Fleissner and Schuchardt, unpublished).…”

“…On their proximal end, the cells of the LaO have axons, which form a common optic tract and terminate in a separate first optic neurophil, the frontal lamina accessoria (fLAcc) (Fleissner et al, 1993a;Frisch et al, 1996). This neurophil is clearly distinct from the huge compound eye lamina (LA) and the caudal lamina accessoria (cLAcc) of the stemmata, one for each of the six stemmata.…”