Immunofluorescence analysis of the internal brain anatomy of Nereis diversicolor (Polychaeta, Annelida)

Abstract

Comparative analyses of neuroanatomical characters can make valuable contributions to the inference of phylogenetic relationships. Whereas investigations in this field are numerous for arthropods, in-depth studies on other protostomes are sparse. Here, we provide a survey of the internal neuroarchitecture of the brain of the aciculate ragworm Nereis diversicolor (Polychaeta, Annelida). Descriptions are based on confocal laser scanning microscope analyses of brain sections labeled with the nuclear marker DAPI and antibodies raised against FMRF-amide, serotonin, and histamine. Autofluorescence of the nervous tissue has been utilized to further elucidate the anatomical structures of the brain. The architecture of two major brain compartments, i.e., the paired mushroom bodies and the central optic neuropil, is described in detail. The findings are compared with existent literature on polychaete neuroanatomy and on arthropod neuroanatomy, and possible phylogenetic implications are outlined.

Comparative neuroanatomy of Caudofoveata, Solenogastres, Polyplacophora, and Scaphopoda (Mollusca) and its phylogenetic implications

“…The neuroarchitecture was revealed by a combination of immunohistochemistry and DAPI nuclear labeling as described in Heuer and Loesel (2008). Depending on the size of the investigated species, the mollusks were either decapitated or Wxed completely overnight in 4% paraformaldehyde in 0.1 M phosphate buVer saline (PBS) at 4°C.…”

The endocrine control of reproduction in Nereidae: a new multi-hormonal model with implications for their functional role in a changing environment

“…For example, oxytocin-like hormones have been identified in mature female N. diversicolor and Perinereis vencourica ganglia (Fewou & Dhainaut-Cortois 1995;Matsushima et al 2002) and vasotocin (vasopressin/oxytocin) -neurophysin is expressed in the developing forebrain of P. dumerilii (Tessmar-Raible et al 2007). Most recently, immunopositive staining for serotonin has been reported in N. diversicolor (Heuer & Loesel 2008). Furthermore, the fact that the supra-oesophageal ganglion of juvenile animals is responsive to these hormones in vivo indicates some inherent mechanistic competency within the neuroendocrine system to interact with these elements.…”

Evolutionary Convergence of Higher Brain Centers Spanning the Protostome-Deuterostome Boundary

“…In most species, Kenyon cells supply calyx neuropils with their dendrites and the pedunculus and lobes with parallel projecting axon-like processes, the latter of which typically bifurcate to form two or more lobes and receive further inputs from other areas of the protocerebrum while providing outputs to mushroom body efferents and recurrent neurons Strausfeld, 2002]. This basic organization is shared by mushroom body-like structures in the brains of polychaete annelids, the Onychophora (lobopods), and all arthropods with the exception of the basal hexapods and the Crustacea [Strausfeld et al, 1995[Strausfeld et al, , 2006Strausfeld, 1998;Heuer and Loesel, 2008]. In most representative species of these taxa, the mushroom bodies serve chemosensory processing functions as their calyces are the targets of olfactory input from primary olfactory neuropils Heuer and Loesel, 2008], and recent studies suggest that the insect mushroom bodies also receive gustatory input from sensory neurons on the mouthparts via neuropils in the deutocerebrum, tritocerebrum and subesophageal ganglion [Schröter and Menzel, 2003;Farris, 2008b].…”

“…This basic organization is shared by mushroom body-like structures in the brains of polychaete annelids, the Onychophora (lobopods), and all arthropods with the exception of the basal hexapods and the Crustacea [Strausfeld et al, 1995[Strausfeld et al, , 2006Strausfeld, 1998;Heuer and Loesel, 2008]. In most representative species of these taxa, the mushroom bodies serve chemosensory processing functions as their calyces are the targets of olfactory input from primary olfactory neuropils Heuer and Loesel, 2008], and recent studies suggest that the insect mushroom bodies also receive gustatory input from sensory neurons on the mouthparts via neuropils in the deutocerebrum, tritocerebrum and subesophageal ganglion [Schröter and Menzel, 2003;Farris, 2008b]. Protostome mushroom bodies are not solely olfactory processing centers, however, as olfactory input is lost in aquatic insects and other A B Fig.…”