QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

This Article Summary Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Reischig, T. Articles by Stengl, M. Search for Related Content PubMed PubMed Citation Articles by Reischig, T. Articles by Stengl, M.

Ectopic transplantation of the accessory medulla restores circadian locomotor rhythms in arrhythmic cockroaches (Leucophaea maderae)

Thomas Reischig and Monika Stengl^*

Biology, Animal Physiology, Philipps Universität Marburg, Karl von Frisch Str., D-35041 Marburg, Germany

View larger version (22K): [in a new window]   Fig. 1. Illustration of the two transplantation methods used in this study. (A) Accessory medulla (AMe)-grafts were exchanged between animals raised in 11 h:11 h L:D and 13 h:13 h L:D cycles. The left (in respect to the body axis) optic lobes were sectioned at least three weeks before the transplantations. (B) The AMe-grafts (in control experiments: medulla-grafts) were transplanted into the right antennal lobe of host animals. The remaining right optic lobes were subsequently removed. See Materials and methods for further details.

View larger version (47K): [in a new window]   Fig. 2. Regained circadian rhythmic locomotor activity in optic lobe-less cockroaches after transplantation of one accessory medulla into the antennal lobe (animal ID 13/84; Table 2). (A) Double-plot activity histograms show circadian wheel-running activity (=24.2 h) in constant darkness before the operation (B; day 34–39, 2-periodogram). The operated cockroach is arrhythmic for 101 days after the operation, as shown in the 2-periodogram (C; day 58–65). Then, the cockroach regains rhythmic activity with =23.7 h, as shown in the 2-periodogram analysis (D; day 142–148; periodogram peak height=40.7%, width=1 h). Additionally, two activity plots show the mean locomotor activity ± S.D. of the animal during the course of a circadian day before (E; day 34–39) and after (F; day 142–148) the transplantation. Histological data of this animal are shown in Fig. 4C,D.

View larger version (38K): [in a new window]   Fig. 3. (A–E) Double-plot activity histogram (A; day 145–156) and 2-periodogram analysis (B; day 150–154; Sokolove significance line=SSL=2 for P=0.01) of another optic lobe-less cockroach (animal ID 13/21; Table 2) shows circadian wheel-running activity (=20.8 h) in constant darkness 148 days after the transplantation. The solid line at day 153 indicates computer failure. (C) The rhythm scan periodogram plot (Qp/2) over the complete length of the wheel-running recording (day 1–167) detects rhythmic peaks in consecutive 10-day-2-periodograms (rhythmicity) before removal of the remaining optic lobe (day 19–39) and after the transplantation (day 143–151). s.p.l. = single periodogram length. Additionally, rhythmic activity can be seen in the two activity plots, which show the averaged locomotor activity ± S.D. of the animal during the course of a circadian day before (D; day 27–39) and after (E; day 150–154) the transplantation.

View larger version (133K): [in a new window]   Fig. 4. PDH-immunoreactivity in an accessory medulla (AMe)-explant as used for transplantations (A) and in the central brains of two postoperatively rhythmic cockroaches (B–D). (A) In the 10-µm paraffin section of an excised AMe-graft, two large- and two medium-sized PDH-ir medulla neurons (PDH-Me) send processes into the AMe. Counterstaining with methylene blue shows unstained somata next to the PDH-Me. (B) Reconstruction of PDH-immunoreactivity in the brain of a postoperatively rhythmic cockroach (animal ID 11/16; Tables 2, 3). Three large- and two medium-sized grafted PDH-ir cells in the antennal lobe (AL; arrow) project via new routes to original arborisation sites in the superior medial and superior lateral protocerebra (SMP and SLP, respectively). Faintly stained PDH-ir neurons in the pars intercerebralis (PI) give rise to spotted staining in the protocerebrum, which can be clearly distinguished from regenerated fibres. a, alpha lobe. (C) Frontal brain section of the animal (animal ID 13/84; Tables 2, 3) in Fig. 2 with regenerated PDH-ir arborisations in the SMP and SLP (arrowheads) and antennal lobe (AL, open arrowhead). Inset: grafted large PDH-ir soma in the anterior AL (arrow). Ca, calyces of the mushroom bodies. (D) A more posterior slice of the same brain shows regenerated fibres invading the protocerebrum via the antenno-glomerular tract (arrowheads). Scale bars: 50 µm (A), 200 µm (B), 100 µm (C,D).