Choline acetyltransferase and NADPH-diaphorase activity in the nervous system and receptor organs of nemerteans

Zaitseva, O. V.; Markosova, T. G.

doi:10.1134/s001249660905010x

Cited by 6 publications

(8 citation statements)

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“…Other sensory structures, detected in addition to the cerebral organs, includes FLIR and ChAT + anterior sensory cells ( asc , Figs. 1 and 2 C, E), which likely contribute to the so-called frontal organs [19, 22, 23, 25], and numerous SLIR cephalic nerves extending anteriorly from the brain ( an , Figs. 1 and 2H).…”

Section: Resultsmentioning

confidence: 99%

“…1 , nk2.2, dach, svp, tll ) and rhynchocoel ( bf1, arx ), two morphological apomorphies of Nemertea [15, 16]. Taking into account that the proboscis is a highly innervated structure [this study; also 15-20, 22, 23, 25, 26, 29, 57, 58, 90], the neuronal genes in the proboscis might be expressed in the developing neuronal network of the organ. Comparable results were obtained by body region-specific transcriptomics of the nemertean Notospermus geniculatus , in which expression of some of the neuronal markers (e.g.…”

Section: Discussionmentioning

confidence: 99%

“…Most nemerteans are active predators, which hunt for their invertebrate prey using a specialized eversible proboscis, a morphological apomorphy of the clade [1,[14][15][16][17][18]. This active lifestyle is accompanied by a relatively complex nervous system, composed of a large, multilobed brain (with two ventral and two dorsal lobes), a pair of lateral medullary nerve cords, extensive peripheral network and multiple specialized sensory organs [17][18][19][20][21][22][23][24][25][26][27][28][29]. Among the latter, the most conspicuous are the so-called cerebral (or cephalic) organs -paired structures of neurosecretory and either chemo-or mechanosensory function, located on the lateral sides of the head [17-23, 28, 30-33].…”

Section: Introductionmentioning

confidence: 99%

“…In the present study, we describe the detailed morphology of the nervous system and gene expression in the brain and cerebral organs of the juveniles of Lineus ruber (Müller, 1774), a directly developing lineid heteronemertean. L. ruber has been studied in past for both adult morphology [20,[22][23][24][25][26][29][30][31] and some aspects of its development [29,37,38], including the molecular patterning of anterior-posterior axis, germ layers and lateral nerve cords [39,40]. Comparison of our data with the existing morphological descriptions of the adult nervous system in L. ruber [20,[22][23][24][25][26][29][30][31] and other closely related species, allows a better understanding of the ontogeny of the complex nemertean nervous system.…”

Section: Introductionmentioning

confidence: 99%

“…L. ruber has been studied in past for both adult morphology [20,[22][23][24][25][26][29][30][31] and some aspects of its development [29,37,38], including the molecular patterning of anterior-posterior axis, germ layers and lateral nerve cords [39,40]. Comparison of our data with the existing morphological descriptions of the adult nervous system in L. ruber [20,[22][23][24][25][26][29][30][31] and other closely related species, allows a better understanding of the ontogeny of the complex nemertean nervous system. Additionally, juxtaposition of gene expression profiles in the developing brain of L. ruber with that of other Spiralia [39,[41][42][43][44][45][46][47][48] can pinpoint similarities and differences in the molecular patterning of the spiralian brains in general, which in turn can inform evolution of the complex nemertean brain.…”

Section: Introductionmentioning

confidence: 99%

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Gene expression in the developing nemertean brain indicates convergent evolution of complex brains in Spiralia

Gąsiorowski

Børve

et al. 2021

Preprint

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Background: Nemertea is a clade of worm-like animals, which belongs to a larger animal group called Spiralia (together with e.g. annelids, flatworms and mollusks). Many of the nemertean species possess a complex central nervous system (CNS) with a prominent brain, and elaborated chemosensory and neuroglandular cerebral organs, which have been suggested as homologues to the annelid mushroom bodies. In order to understand the developmental and evolutionary origins of complex nemertean brain, we investigated details of neuroanatomy and gene expression in the brain and cerebral organs of the juveniles of nemertean Lineus ruber. Results: In the hatched juveniles the CNS is already composed of all major elements present in the adults, including the brain (with dorsal and ventral lobes), paired longitudinal lateral nerve cords and an unpaired dorsal nerve cord. The TEM investigation of the juvenile cerebral organ revealed that the structure is already composed of several distinct cell types present also in the adults. We further investigated the expression of twelve transcription factors commonly used as brain and cell type markers in bilaterian brains, including genes specific for annelid mushroom bodies. The expression of the investigated genes in the brain is region-specific and divides the entire organ into several molecularly distinct areas, partially overlapping with the morphological compartments. Additionally, we detected expression of mushroom body specific genes in the developing cerebral organs. Conclusions: At the moment of hatching, the juveniles of L. ruber already have a similar neuroarchitecture as adult worms, which suggests that further neural development is mostly related with increase in the size but not in complexity. Comparison in the gene expression between L. ruber and the annelid Platynereis dumerilii and other spiralians, indicates that the complex brains present in those two species evolved convergently by independent expansion of non-homologues regions of the simpler brain present in their common ancestor. The similarities in gene expression in mushroom bodies and cerebral organs might be a result of the convergent recruitment of the same genes into patterning of non-homologues organs or the results of more complicated evolutionary processes, in which conserved and novel cell types contribute to the non-homologues structures.

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