Limits...
Circadian pacemaker coupling by multi-peptidergic neurons in the cockroach Leucophaea maderae.

Soehler S, Stengl M, Reischig T - Cell Tissue Res. (2011)

Bottom Line: Although two-thirds of all PDF-expressing medulla neurons coexpressed FMRFamide and orcokinin immunoreactivity in their somata, colocalization of PDF and FMRFamide immunoreactivity was observed in only a few termination sites.Colocalization of PDF and orcokinin immunoreactivity was never observed in any of the terminals or optic commissures.We suggest that circadian pacemaker cells employ axonal peptide sorting to phase-control physiological processes at specific times of the day.

View Article: PubMed Central - PubMed

Affiliation: Department of Natural Sciences, Animal Physiology, University of Kassel, Heinrich-Plett-Strasse 40, 34132 Kassel, Germany.

ABSTRACT
Lesion and transplantation studies in the cockroach, Leucophaea maderae, have located its bilaterally symmetric circadian pacemakers necessary for driving circadian locomotor activity rhythms to the accessory medulla of the optic lobes. The accessory medulla comprises a network of peptidergic neurons, including pigment-dispersing factor (PDF)-expressing presumptive circadian pacemaker cells. At least three of the PDF-expressing neurons directly connect the two accessory medullae, apparently as a circadian coupling pathway. Here, the PDF-expressing circadian coupling pathways were examined for peptide colocalization by tracer experiments and double-label immunohistochemistry with antisera against PDF, FMRFamide, and Asn(13)-orcokinin. A fourth group of contralaterally projecting medulla neurons was identified, additional to the three known groups. Group one of the contralaterally projecting medulla neurons contained up to four PDF-expressing cells. Of these, three medium-sized PDF-immunoreactive neurons coexpressed FMRFamide and Asn(13)-orcokinin immunoreactivity. However, the contralaterally projecting largest PDF neuron showed no further peptide colocalization, as was also the case for the other large PDF-expressing medulla cells, allowing the easy identification of this cell group. Although two-thirds of all PDF-expressing medulla neurons coexpressed FMRFamide and orcokinin immunoreactivity in their somata, colocalization of PDF and FMRFamide immunoreactivity was observed in only a few termination sites. Colocalization of PDF and orcokinin immunoreactivity was never observed in any of the terminals or optic commissures. We suggest that circadian pacemaker cells employ axonal peptide sorting to phase-control physiological processes at specific times of the day.

Show MeSH

Related in: MedlinePlus

Colocalization of PDF and FMRFamide immunoreactivity in neurons and neuropil of the accessory medulla (AMe) of the cockroach. Confocal laser scan images were obtained from vibratome sections of the accessory medulla showing PDF-immunoreactive (blue) and FMRFamide-immunoreactive (red) neurons. Left Overlay images. a, b Maximum projections from stacks of optical sections. c Single optical section. a1-3 Neurons of the small (small open arrowheads), medium-sized (large open arrowhead), and large anterior PDFMe (large filled arrows). b1-3 Posterior PDFMe comprising small (open triangles) and large (filled triangles) cells. All small, but no large, posterior PDFMe showed colocalized PDF/FMRFamide immunoreactivity (LoVT lobula valley tract). c1-3 In the AMe, weakly labeled PDF-ir varicosities (open arrowheads) in the noduli showed colocalized PDF/FMRFamide immunoreactivity, whereas large and intensely labeled PDF-ir varicosities (filled arrowheads) in the internodular neuropil did not. Bars 50 μm (a), 25 μm (b), 100 μm (c)
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3046342&req=5

Fig2: Colocalization of PDF and FMRFamide immunoreactivity in neurons and neuropil of the accessory medulla (AMe) of the cockroach. Confocal laser scan images were obtained from vibratome sections of the accessory medulla showing PDF-immunoreactive (blue) and FMRFamide-immunoreactive (red) neurons. Left Overlay images. a, b Maximum projections from stacks of optical sections. c Single optical section. a1-3 Neurons of the small (small open arrowheads), medium-sized (large open arrowhead), and large anterior PDFMe (large filled arrows). b1-3 Posterior PDFMe comprising small (open triangles) and large (filled triangles) cells. All small, but no large, posterior PDFMe showed colocalized PDF/FMRFamide immunoreactivity (LoVT lobula valley tract). c1-3 In the AMe, weakly labeled PDF-ir varicosities (open arrowheads) in the noduli showed colocalized PDF/FMRFamide immunoreactivity, whereas large and intensely labeled PDF-ir varicosities (filled arrowheads) in the internodular neuropil did not. Bars 50 μm (a), 25 μm (b), 100 μm (c)

Mentions: Double-labeling with anti-FMRFamide and anti-Drosophila-PDF revealed colocalized immunoreactivities in subgroups of the PDFMe. All small and all medium-sized anterior PDFMe showed additional FMRFamide immunoreactivity, whereas the large PDFMe never did (Fig. 2a; for numbers of PDFMe, see Table 1). Evaluation of the posterior PDFMe revealed that all small posterior PDFMe were additionally FMRFamide-ir, whereas large posterior PDFMe were not (Fig. 2b, Table 1), except in one case. The cell counts (Table 1) showed that the sum of non-FMRFamide-ir anterior and non-FMRFamide-ir posterior PDFMe was, in most cases, 6 neurons (n = 21 of 25). In cases where no non-FMRFamide-ir PDFMe were found among the posterior PDFMe, six of them were found among the anterior PDFMe (n = 5 of 25). In one preparation, six large posterior PDFMe were present but no large anterior PDFMe. In fiber projections, the colocalization of PDF and FMRFamide immunoreactivity was found only in three areas of the brain, namely in the AMe (Fig. 2c), in a dorsal part of the superior lateral protocerebrum (dSLP, Fig. 3a), and in the posterior optic tubercle (POTu, Fig. 3b). Contrary to previous studies (Reischig and Stengl 1996, 2003a), PDF-ir fibers with varicosities were also identified in the nodular neuropil, in addition to the shell neuropil (including the anterior neuropil) of the AMe. The PDF-ir varicosities of the nodular neuropil exhibited far lower labeling intensity and were generally more irregularly shaped than the strongly labeled PDF-ir varicosities of shell and internodular neuropil (Fig. 2c). Only these weakly labeled nodular PDF-ir projections exhibited additional FMRFamide immunoreactivity. Moreover, the AMe was densely invaded by FMRFamide-ir fibers without additional PDF immunoreactivity. Only PDF/FMRFamide-ir fibers occurred in the dSLP, and no fibers with PDF immunoreactivity alone. Many fibers with FMRFamide immunoreactivity alone were also detected in the dSLP. The origin of these fibers remained unclear. The POTu contained PDF/FMRFamide-ir fibers, fibers that expressed only PDF immunoreactivity, and fibers with only FMRFamide immunoreactivity. As in the dSLP, the origin of the FMRFamide-ir fibers in the POTu remained unclear. As shown previously, FMRFamide immunoreactivity was also present in other neuronal groups of the AMe next to the small and medium-sized PDFMe, namely the MNe, the VPNe, the DFVNe including non-PDF-ir and PDF-ir neurons, and the VNe including non-PDF-ir and PDF-ir neurons. Cell counts generally confirmed previous work (Soehler et al. 2008; Table 2).Fig. 2


Circadian pacemaker coupling by multi-peptidergic neurons in the cockroach Leucophaea maderae.

Soehler S, Stengl M, Reischig T - Cell Tissue Res. (2011)

Colocalization of PDF and FMRFamide immunoreactivity in neurons and neuropil of the accessory medulla (AMe) of the cockroach. Confocal laser scan images were obtained from vibratome sections of the accessory medulla showing PDF-immunoreactive (blue) and FMRFamide-immunoreactive (red) neurons. Left Overlay images. a, b Maximum projections from stacks of optical sections. c Single optical section. a1-3 Neurons of the small (small open arrowheads), medium-sized (large open arrowhead), and large anterior PDFMe (large filled arrows). b1-3 Posterior PDFMe comprising small (open triangles) and large (filled triangles) cells. All small, but no large, posterior PDFMe showed colocalized PDF/FMRFamide immunoreactivity (LoVT lobula valley tract). c1-3 In the AMe, weakly labeled PDF-ir varicosities (open arrowheads) in the noduli showed colocalized PDF/FMRFamide immunoreactivity, whereas large and intensely labeled PDF-ir varicosities (filled arrowheads) in the internodular neuropil did not. Bars 50 μm (a), 25 μm (b), 100 μm (c)
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3046342&req=5

Fig2: Colocalization of PDF and FMRFamide immunoreactivity in neurons and neuropil of the accessory medulla (AMe) of the cockroach. Confocal laser scan images were obtained from vibratome sections of the accessory medulla showing PDF-immunoreactive (blue) and FMRFamide-immunoreactive (red) neurons. Left Overlay images. a, b Maximum projections from stacks of optical sections. c Single optical section. a1-3 Neurons of the small (small open arrowheads), medium-sized (large open arrowhead), and large anterior PDFMe (large filled arrows). b1-3 Posterior PDFMe comprising small (open triangles) and large (filled triangles) cells. All small, but no large, posterior PDFMe showed colocalized PDF/FMRFamide immunoreactivity (LoVT lobula valley tract). c1-3 In the AMe, weakly labeled PDF-ir varicosities (open arrowheads) in the noduli showed colocalized PDF/FMRFamide immunoreactivity, whereas large and intensely labeled PDF-ir varicosities (filled arrowheads) in the internodular neuropil did not. Bars 50 μm (a), 25 μm (b), 100 μm (c)
Mentions: Double-labeling with anti-FMRFamide and anti-Drosophila-PDF revealed colocalized immunoreactivities in subgroups of the PDFMe. All small and all medium-sized anterior PDFMe showed additional FMRFamide immunoreactivity, whereas the large PDFMe never did (Fig. 2a; for numbers of PDFMe, see Table 1). Evaluation of the posterior PDFMe revealed that all small posterior PDFMe were additionally FMRFamide-ir, whereas large posterior PDFMe were not (Fig. 2b, Table 1), except in one case. The cell counts (Table 1) showed that the sum of non-FMRFamide-ir anterior and non-FMRFamide-ir posterior PDFMe was, in most cases, 6 neurons (n = 21 of 25). In cases where no non-FMRFamide-ir PDFMe were found among the posterior PDFMe, six of them were found among the anterior PDFMe (n = 5 of 25). In one preparation, six large posterior PDFMe were present but no large anterior PDFMe. In fiber projections, the colocalization of PDF and FMRFamide immunoreactivity was found only in three areas of the brain, namely in the AMe (Fig. 2c), in a dorsal part of the superior lateral protocerebrum (dSLP, Fig. 3a), and in the posterior optic tubercle (POTu, Fig. 3b). Contrary to previous studies (Reischig and Stengl 1996, 2003a), PDF-ir fibers with varicosities were also identified in the nodular neuropil, in addition to the shell neuropil (including the anterior neuropil) of the AMe. The PDF-ir varicosities of the nodular neuropil exhibited far lower labeling intensity and were generally more irregularly shaped than the strongly labeled PDF-ir varicosities of shell and internodular neuropil (Fig. 2c). Only these weakly labeled nodular PDF-ir projections exhibited additional FMRFamide immunoreactivity. Moreover, the AMe was densely invaded by FMRFamide-ir fibers without additional PDF immunoreactivity. Only PDF/FMRFamide-ir fibers occurred in the dSLP, and no fibers with PDF immunoreactivity alone. Many fibers with FMRFamide immunoreactivity alone were also detected in the dSLP. The origin of these fibers remained unclear. The POTu contained PDF/FMRFamide-ir fibers, fibers that expressed only PDF immunoreactivity, and fibers with only FMRFamide immunoreactivity. As in the dSLP, the origin of the FMRFamide-ir fibers in the POTu remained unclear. As shown previously, FMRFamide immunoreactivity was also present in other neuronal groups of the AMe next to the small and medium-sized PDFMe, namely the MNe, the VPNe, the DFVNe including non-PDF-ir and PDF-ir neurons, and the VNe including non-PDF-ir and PDF-ir neurons. Cell counts generally confirmed previous work (Soehler et al. 2008; Table 2).Fig. 2

Bottom Line: Although two-thirds of all PDF-expressing medulla neurons coexpressed FMRFamide and orcokinin immunoreactivity in their somata, colocalization of PDF and FMRFamide immunoreactivity was observed in only a few termination sites.Colocalization of PDF and orcokinin immunoreactivity was never observed in any of the terminals or optic commissures.We suggest that circadian pacemaker cells employ axonal peptide sorting to phase-control physiological processes at specific times of the day.

View Article: PubMed Central - PubMed

Affiliation: Department of Natural Sciences, Animal Physiology, University of Kassel, Heinrich-Plett-Strasse 40, 34132 Kassel, Germany.

ABSTRACT
Lesion and transplantation studies in the cockroach, Leucophaea maderae, have located its bilaterally symmetric circadian pacemakers necessary for driving circadian locomotor activity rhythms to the accessory medulla of the optic lobes. The accessory medulla comprises a network of peptidergic neurons, including pigment-dispersing factor (PDF)-expressing presumptive circadian pacemaker cells. At least three of the PDF-expressing neurons directly connect the two accessory medullae, apparently as a circadian coupling pathway. Here, the PDF-expressing circadian coupling pathways were examined for peptide colocalization by tracer experiments and double-label immunohistochemistry with antisera against PDF, FMRFamide, and Asn(13)-orcokinin. A fourth group of contralaterally projecting medulla neurons was identified, additional to the three known groups. Group one of the contralaterally projecting medulla neurons contained up to four PDF-expressing cells. Of these, three medium-sized PDF-immunoreactive neurons coexpressed FMRFamide and Asn(13)-orcokinin immunoreactivity. However, the contralaterally projecting largest PDF neuron showed no further peptide colocalization, as was also the case for the other large PDF-expressing medulla cells, allowing the easy identification of this cell group. Although two-thirds of all PDF-expressing medulla neurons coexpressed FMRFamide and orcokinin immunoreactivity in their somata, colocalization of PDF and FMRFamide immunoreactivity was observed in only a few termination sites. Colocalization of PDF and orcokinin immunoreactivity was never observed in any of the terminals or optic commissures. We suggest that circadian pacemaker cells employ axonal peptide sorting to phase-control physiological processes at specific times of the day.

Show MeSH
Related in: MedlinePlus