Nemertean nervous system : a comparative analysis

Most described nemerteans are marine benthic hunters. Thus, they possess a well developed nervous system. Basically, the nervous system comprises a four lobed brain, two main lateral medullary cords, some minor nerves, various nerve plexus and sensory structures. The brain and lateral nerve cords are composed of a central neuropil and a layer of neuronal cell somata, which are homogeneously distributed around the neuropil. Formerly, nemerteans fell into three major taxa, the Palaeo- Hetero- and Hoplonemertea. But this classification has been controversially discussed in recent years. Especially the monophyly of palaeonemerteans is matter of debate. But there is a consensus that Hetero- and Hoplonemertea are monophyletic and form an evolutionary lineage called Neonemertea. In recent years, neuroanatomical studies by immunohistochemistry have yielded promising data to contribute to unraveling the phylogeny of the invertebrate metazoans. For Nemertea, however, only one species has been investigated, which most likely shows derived characters states. Therefore the nervous system of 16 species of different evolutionary lineages of nemerteans was reinvestigated using different techniques. Azan staining was chosen to reveal the overall anatomy of the nervous system, additionally immunohistochemical methods were applied to reveal the details. A careful analysis of the nervous system showed considerable differences in the structure of the peripheral nervous system of even closely related species. A number of 61 characters concerning the morphological elements of the nervous system resulted from this investigation. The analysis yielded one most parsimonious tree. According to this result hoplonemerteans and heteronemerteans are monophyletic and form a monophyletic taxon called Neonemertea. Whether Palaeonemertea are mono- or paraphyletic remains uncertain due to the unknown outgroup conditions. Compared to other recently published results, the nervous system, although being just one organ system, turned out to be a valuable morphological system to infer nemertean phylogeny

Lophotrochozoan neuroanatomy: An analysis of the brain and nervous system of Lineus viridis(Nemertea) using different staining techniques

<p>Abstract</p> <p>Background</p> <p>The now thriving field of neurophylogeny that links the morphology of the nervous system to early evolutionary events relies heavily on detailed descriptions of the neuronal architecture of taxa under scrutiny. While recent accounts on the nervous system of a number of animal clades such as arthropods, annelids, and molluscs are abundant, in depth studies of the neuroanatomy of nemerteans are still wanting. In this study, we used different staining techniques and confocal laser scanning microscopy to reveal the architecture of the nervous system of <it>Lineus viridis </it>with high anatomical resolution.</p> <p>Results</p> <p>In <it>L. viridis</it>, the peripheral nervous system comprises four distinct but interconnected nerve plexus. The central nervous system consists of a pair of medullary cords and a brain. The brain surrounds the proboscis and is subdivided into four voluminous lobes and a ring of commissural tracts. The brain is well developed and contains thousands of neurons. It does not reveal compartmentalized neuropils found in other animal groups with elaborate cerebral ganglia.</p> <p>Conclusions</p> <p>The detailed analysis of the nemertean nervous system presented in this study does not support any hypothesis on the phylogenetic position of Nemertea within Lophotrochozoa. Neuroanatomical characters that are described here are either common in other lophotrochozoan taxa or are seemingly restricted to nemerteans. Since detailed descriptions of the nervous system of adults in other nemertean species have not been available so far, this study may serve as a basis for future studies that might add data to the unsettled question of the nemertean ground pattern and the position of this taxon within the phylogenetic tree.</p

On the role of the proventricle region in reproduction and regeneration in Typosyllis antoni (Annelida: Syllidae)

Background: Syllids are a species rich annelid family possessing remarkable regenerative ability, which is not only the response after traumatic injury, but also a key step during the life cycle of several syllid taxa. In these animals the posterior part of the body becomes an epitoke and is later detached as a distinct unit named stolon. Such a sexual reproductive mode is named schizogamy or stolonization. The prostomium and the proventricle, a modified foregut structure, have been proposed to have a control function during this process, though the concrete mechanisms behind it have never been elucidated. Results: By using different experimental set-ups, histology and immunohistochemistry combined with subsequent cLSM analyzes, we investigate and document the regeneration and stolonization in specimens of Typosyllis antoni that were amputated at different levels throughout the antero-posterior body axis. The removal of the anterior end including the proventricle implies an incomplete anterior regeneration as well as severe deviations from the usual reproductive pattern, i.e. accelerated stolonization, masculinization and the occurrence of aberrant stolons. The detailed anatomy of aberrant stolons is described. A histological study of the proventricle revealed no signs of glandular or secretory structures. The ventricle and the caeca are composed of glandular tissue but they are not involved in the reproductive and regenerative processes. Conclusions: As in other investigated syllids, the proventricle region has a significant role during stolonization and reproduction processes in Typosyllis antoni. When the proventricle region is absent, anterior and posterior regeneration are considerably deviated from the general patterns. However, proventricle ultrastructure does not show any glandular component, thereby questioning a direct involvement of this organ itself in the control of reproduction and regeneration. Our findings offer a comprehensive starting point for further studies of regeneration and reproductive control in syllids as well as annelids in general

Friedel-Crafts Type Methylation with Dimethylhalonium Salts

The dimethylchloronium salt [Me2Cl][Al(OTeF5)(4)] is used to methylate electron-deficient aromatic systems in Friedel-Crafts type reactions as shown by the synthesis ofN-methylated cations, such as [MeNC5F5](+), [MeNC5F4I](+), and [MeN3C3F3](+). To gain a better understanding of such fundamental Friedel-Crafts reactions, the role of the dimethylchloronium cation has been evaluated by quantum-chemical calculations

Conductivity and Redox Potentials of Ionic Liquid Trihalogen Monoanions [X3]−, [XY2]−, and [BrF4]− (X=Cl, Br, I and Y=Cl, Br)

The ionic liquid (IL) trihalogen monoanions [N2221][X3]− and [N2221][XY2]− ([N2221]+=triethylmethylammonium, X=Cl, Br, I, Y=Cl, Br) were investigated electrochemically via temperature dependent conductance and cyclic voltammetry (CV) measurements. The polyhalogen monoanions were measured both as neat salts and as double salts in 1‐butyl‐1‐methyl‐pyrrolidinium trifluoromethane‐sulfonate ([BMP][OTf], [X3]−/[XY2]− 0.5 M). Lighter IL trihalogen monoanions displayed higher conductivities than their heavier homologues, with [Cl3]− being 1.1 and 3.7 times greater than [Br3]− and [I3]−, respectively. The addition of [BMP][OTf] reduced the conductivity significantly. Within the group of polyhalogen monoanions, the oxidation potential develops in the series [Cl3]−>[BrCl2]−>[Br3]−>[IBr2]−>[ICl2]−>[I3]−. The redox potential of the interhalogen monoanions was found to be primarily determined by the central halogen, I in [ICl2]− and [IBr2]−, and Br in [BrCl2]−. Additionally, tetrafluorobromate(III) ([N2221]+[BrF4]−) was analyzed via CV in MeCN at 0 °C, yielding a single reversible redox process ([BrF2]−/[BrF4]−)

The central nervous system of Oweniidae (Annelida) and its implications for the structure of the ancestral annelid brain

Figure S1: Histology Orrhage’s Owenia fusiformis. A: slide showing sections of Owenia fusiformis. B: Intermediate filaments (if) cross the neuropil of the brain (br). The ecm of the epidermis is less prominent where the neuropil layer is above it. C: Posterior part of the brain (br). if: intermediate filaments. (JPG 10649 kb

Non-classical polyinterhalides of chlorine monofluoride: experimental and theoretical characterization of [F(ClF)3]−

We present the synthesis and characterization of the first non-classical Cl(I) polyinterhalide [NMe4][F(ClF)3] as well as the homologous polychloride [NPr3Me][Cl7]. Both salts were obtained from the reaction of the corresponding ammonium chlorides with ClF or Cl2, respectively. Quantum-chemical investigations predict an unexpected planar structure for the [F(ClF)3]− anion

(Noble Gas)n-NC+ Molecular Ions in Noble Gas Matrices: Matrix Infrared Spectra and Electronic Structure Calculations

An investigation of pulsed-laser-ablated Zn, Cd and Hg metal atom reactions with HCN under excess argon during co-deposition with laser-ablated Hg atoms from a dental amalgam target also provided Hg emissions capable of photoionization of the CN photo-dissociation product. A new band at 1933.4 cm−1 in the region of the CN and CN+ gas-phase fundamental absorptions that appeared upon annealing the matrix to 20 K after sample deposition, and disappeared upon UV photolysis is assigned to (Ar)nCN+, our key finding. It is not possible to determine the n coefficient exactly, but structure calculations suggest that one, two, three or four argon atoms can solvate the CN+ cation in an argon matrix with C−N absorptions calculated (B3LYP) to be between 2317.2 and 2319.8 cm−1. Similar bands were observed in solid krypton at 1920.5, in solid xenon at 1935.4 and in solid neon at 1947.8 cm−1. H13CN reagent gave an 1892.3 absorption with shift instead, and a 12/13 isotopic frequency ratio–nearly the same as found for 13CN+ itself in the gas phase and in the argon matrix. The CN+ molecular ion serves as a useful infrared probe to examine Ng clusters. The following ion reactions are believed to occur here: the first step upon sample deposition is assisted by a focused pulsed YAG laser, and the second step occurs on sample annealing: (Ar)2++CN→Ar+CN+→(Ar)nCN+

Concomitant deficits in working memory and fear extinction are functionally dissociated from reduced anxiety in metabotropic glutamate receptor 7-deficient mice

Metabotropic glutamate receptor 7 (mGluR7), a receptor with a distinct brain distribution and a putative role in anxiety, emotional responding, and spatial working memory, could be an interesting therapeutic target for fear and anxiety disorders. mGluR7-deficient (mGluR7 / ) mice showed essentially normal performance in tests for neuromotor and exploratory activity and passive avoidance learning but prominent anxiolytic behavior in two anxiety tests. They showed a delayed learning curve during the acquisition of the hidden-platform water maze, and three interspersed probe trials indicated that mGluR7 / mice were slower to acquire spatial information. Working memory in the water maze task and the radial arm maze was impaired in mGluR7 / mice compared with mGluR7 / . mGluR7 / mice also displayed a higher resistance to extinction of fear-elicited response suppression in a conditioned emotional response protocol. In a non-fear-based water maze protocol, mGluR7 / mice displayed similar delayed extinction. These observed behavioral changes are probably not attributable to changes inAMPAorNMDAreceptor function because expression levels of AMPAand NMDA receptors were unaltered. Extinction of conditioned fear is an active and context-dependent form of inhibitory learning and an experimental model for therapeutic fear reduction. It appears to depend on glutamatergic and higher-level brain functions similar to those involved in spatial working memory but functionally dissociated from those that mediate constitutional responses in anxiety tests

Endocrine consequences of immune checkpoint inhibitors

Immune checkpoints inhibitors have fundamentally changed the management of oncologic patients. These treatments consist of monoclonal antibodies directed against CTLA-4 (cytotoxic T-lymphocyte antigen 4), PD-1 (programmed cell death protein-1) and PD-L1 (one of its ligands). By blocking these receptors or ligands, the antibodies reverse the immune tolerance induced by the cancerous cell on the T-lymphocyte and favour lymphocytic reactivation and anti-tumor activity. Immune tolerance to auto-antigens is maintained with the help of these checkpoints. Targeting them can lead to auto-immune side effects. These latter mostly impact the cutaneous and digestive system, but the endocrine glands are not spared. In this article, we provide monitoring and treatment algorithms for these endocrine immune side effects. An early diagnosis followed by the appropriate treatment would reduce their negative impact on the oncologic care