Monoamine- and peptide-containing elements in the body wall and nervous trunks of nemerteans

Localization and morphological peculiarities of cateholamine-containing (CA-C), serotonin-(5HTIR), neurotensin-(NT-IR) and FMRFamide-immunoreactive (FMRFa-Ir) cells and processes in the body wall and lateral nervous trunks of nemerteans were investigated. The following nemertean species from three orders occurring in the White Sea were studied by fluorescent histochemistry and by immunohistochemistry: Lineus viridis, Lineus ruber and Cerebratulus sp. (Heteronemertini), Cephalothrix linearis (Palaeonemertini), and Amphiporus lactifloreus (Hoplonemertini). The similarity and characteristics of morphological types of monoamine-and peptide-containing elements, their distribution and possible participation in regulation of some functions in different nemertean species and in other invertebrates are discussed. We suggest that 5HT-IR and CA-C bi-and multipolar intra-and subepidermal open-type cells prevailing in the body wall perform a receptive function, while the FMRFa-Ir and NT-IR neurons of the nerve trunks and body wall are responsible for efferent innervation of musculature and connections within the nervous system.     

Isoenzyme differences between three closely related species of Lineus (Heteronemertea)

Starch-gel electrophoresis was employed to compare six enzymes in three closely related species of nemertean worms, Lineus ruber (Müller, 1774), Lineus sanguineus (Rathke, 1799), and Linens viridis (Müller, 1774). Differences in mobility recorded for most of the enzyme loci examined support the hypothesis that these nemerteans are distinct taxa.     

Nemerteans of the genus <Emphasis Type="Italic">Ototyphlonemertes</Emphasis> (Enopla: Ototyphlonemertidae) from Van Phong Bay (South Vietnam)

Two species of the interstitial nemerteans from the intertidal zone of Van Phong Bay (southern Vietnam) are described. By the structure of the proboscis and statocysts, the nemertean Ototyphlonemertes ani sp. n. can be referred to the species group “Lactea” (sensu Envall, Norenburg, 2001), but it differs from other species of this group by the presence of cerebral organs and caudal cirri. The second species new for the region is very similar to O. martynovi, but differs from it in having 2 to 3 cephalic cirri in group C (instead of 4 to 6 cirri found in O. martynovi).     

The nervous system of Isodiametra pulchra (Acoela) with a discussion on the neuroanatomy of the Xenacoelomorpha and its evolutionary implications

Introduction

Acoels are microscopic marine worms that have become the focus of renewed debate and research due to their placement at the base of the Bilateria by molecular phylogenies. To date, Isodiametra pulchra is the most promising ??model acoel?? as it can be cultured and gene knockdown can be performed with double-stranded RNA. Despite its well-known morphology data on the nervous system are scarce. Therefore we examined this organ using various microscopic techniques, including histology, conventional histochemistry, electron microscopy, and immunocytochemistry in combination with CLSM and discuss our results in light of recently established phylogenies.

Results

The nervous system of Isodiametra pulchra consists of a bilobed brain with a dorsal posterior commissure, a frontal ring and tracts, four pairs of longitudinal neurite bundles, as well as a supramuscular and submuscular plexus. Serotonin-like immunoreactivity (SLI) is displayed in parts of the brain, the longitudinal neurite bundles and a large part of the supramuscular plexus, while FMRFamide-like immunoreactivity (RFLI) is displayed in parts of the brain and a distinct set of neurons, the longitudinal neurite bundles and the submuscular plexus. Despite this overlap SLI and RFLI are never colocalized. Most remarkable though is the presence of a distinct functional neuro-muscular system consisting of the statocyst, tracts, motor neurons and inner muscles, as well as the presence of various muscles that differ with regard to their ultrastructure and innervation.

Conclusions

The nervous system of Isodiametra pulchra consists of an insunk, bilobed brain, a peripheral part for perception and innervation of the smooth body-wall musculature as well as tracts and motor neurons that together with pseudostriated inner muscles are responsible for steering and quick movements. The insunk, bilobed brains with two to three commissures found in numerous acoels are homologous and evolved from a ring-commissural brain that was present in the stem species of acoelomorphs. The acoelomorph brain is bipartite, consisting of a Six3/6-dependend animal pole nervous system that persists throughout adulthood and an axial nervous system that does not develop by exhibiting a staggered pattern of conserved regulatory genes as in other bilaterians but by a nested pattern of these genes. This indicates that acoelomorphs stem from an ancestor with a simple brain or with a biphasic life cycle.     

Statistical Parsimony Networks and Species Assemblages in Cephalotrichid Nemerteans (Nemertea)

Background

It has been suggested that statistical parsimony network analysis could be used to get an indication of species represented in a set of nucleotide data, and the approach has been used to discuss species boundaries in some taxa.

Methodology/Principal Findings

Based on 635 base pairs of the mitochondrial protein-coding gene cytochrome c oxidase I (COI), we analyzed 152 nemertean specimens using statistical parsimony network analysis with the connection probability set to 95%. The analysis revealed 15 distinct networks together with seven singletons. Statistical parsimony yielded three networks supporting the species status of Cephalothrix rufifrons, C. major and C. spiralis as they currently have been delineated by morphological characters and geographical location. Many other networks contained haplotypes from nearby geographical locations. Cladistic structure by maximum likelihood analysis overall supported the network analysis, but indicated a false positive result where subnetworks should have been connected into one network/species. This probably is caused by undersampling of the intraspecific haplotype diversity.

Conclusions/Significance

Statistical parsimony network analysis provides a rapid and useful tool for detecting possible undescribed/cryptic species among cephalotrichid nemerteans based on COI gene. It should be combined with phylogenetic analysis to get indications of false positive results, i.e., subnetworks that would have been connected with more extensive haplotype sampling.     

On the identity of two Antarctic brooding nemerteans: redescription of Antarctonemertes valida (Bürger, 1893) and description of a new species in the genus Antarctonemertes Friedrich, 1955 (Nemertea, Hoplonemertea)

Nemerteans (ribbon worms) constitute an abundant and occasionally conspicuous group of benthic invertebrates in the Southern Ocean. Although recent work has confirmed that this group is far more diverse than previously recognized, the Antarctic nemertean fauna remains poorly understood when compared to other geographic regions. In most cases, the taxonomic information on the known nemertean fauna is incomplete for this region and/or has been inappropriately documented. As a consequence, many of the species described are considered species inquirendae. Among the nearly 50 species described so far for the Southern Ocean, two hoplonemerteans are known to brood eggs in cocoons: Amphiporus incubator Joubin, 1914 and Amphiporus michaelseni Bürger, 1895a. Here, we redescribe Antarctonemertes valida (Bürger, 1893), a senior synonym of A. michaelseni, and describe a new congeneric species, Antarctonemertes riesgoae sp. nov. Both species show a similar reproductive strategy by brooding their cocoons, and similar external appearance, but clearly differ in other aspects of their morphology, such as the cephalic coloration pattern and the number of proboscidial nerves. We provide novel information about their life habitus, reproductive behaviour, internal anatomy, and their phylogenetic placement within hoplonemerteans using one nuclear (28S rRNA) and two mitochondrial [cytochrome c oxidase subunit I (COI) and 16S rRNA] markers. We also provide a parsimony haplotype network using 16S rRNA, COI, and the internal transcribed spacer region 2 (ITS-2) showing a clear distinction between individuals of both species. Our results stress the need of combining molecular and morphological information when dealing with closely related species of nemerteans.     

Hubrecht,Macfarlane, Jensen and Willmer: on the nature and testability of four versions of the nemertean theory of vertebrate origins

Four authors (A. A. W. Hubrecht, J. M. Macfarlane, D. D. Jensen and E. N. Willmer) have argued that nemerteans are the proximal invertebrate ancestors of vertebrates. While all these authors accept certain homologies (i.e. vertebrate pituitary and notochord with nemertean proboscis invagination and proboscis sheath or mesoderm), there is considerable variation among them in the derivation of the vertebrate nervous system, sense organs and foregut apertures. For example, Hubrecht suggests that the vertebrate nervous system developed from a solid dorsal nerve found in some nemerteans; Macfarlane suggests it developed by fusion of the left and right solid brains of nemerteans; Jensen suggests that the vertebrate tubular nervous system developed by the backward extension of the nemertean frontal organ and fusion with the nemertean dorsal and ventral brain ganglia. Modern EM, histochemical and biochemical methods can test empirically the four theories. Research testing these theories will also test the more popular acraniate theory, since that theory implies that vertebrate head structures evolved de novo in chordates and that no homologies should exist between vertebrate and nemertean head structures.     

Traffic of Leukocytes and Cytokine Up-regulation in the Central Nervous System in a Murine Model of Neuroparacoccidioidomycosis

Background

Paracoccidioidomycosis is the most important systemic mycosis in South America. In the last decades, it was observed that central nervous system involvement is frequent, occurring in 12.5 % of the cases. The aim of this study was to report the early inflammatory changes associated with an experimental model of neuroparacoccidioidomycosis (NPCM).

Methods

C57BL/6 mice were infected by intracranial route with 10⁶ yeast cells of PB18 strain of Paracoccidioides brasiliensis. Leukocyte–endothelium interactions were assessed by intravital microscopy 1, 2, 4, and 8 weeks post-infection (p.i.). Chemokine/cytokine levels in the brain and histopathological changes were assessed 4 and 8 weeks p.i..

Results

Intravital microscopy analysis revealed a progressive increase in leukocyte recruitment in the vessels of pia mater with a peak 4 weeks p.i. The chemokine CXCL9 was increased at 4 and 8 weeks p.i., while CCL2, CCL3, and CCL5 were increased at 8 weeks p.i. Histopathological analysis revealed the infiltration of inflammatory cells and the development of progressive granulomatous meningoencephalitis. CCL3 levels correlated with clinical manifestations of disease, as measured by the SHIRPA battery.

Conclusions

The experimental model of NPCM showed increased leukocyte recruitment associated with increased expression of chemokines and nervous tissue inflammation which correlated with clinical manifestations of disease.     

The lipopolysaccharides (O-antigens) of Rhodopseudomonas viridis

The present paper deals with the isolation, and chemical and serological characterization of the O-antigens (lipopolysaccharides, LPS) of the photosynthetic gram-negative bacterium Rhodopseudomonas viridis. The LPS are extractable with hot phenol/water, but unlike the phenol-soluble LPS of the closely related species Rhodopseudomonas palustris, the R. viridis O-antigens are preferentially extracted into the water phase. A mixture of phenol/chloroform/petroleum ether (PCP-method) does not extract the R. viridis LPS. All R. viridis LPS investigated belong to the same chemotype, the polysaccharide moiety of these O-antigens being composed of 3-O-methyl-l-xylose, 3-O-methyl-d-mannose, d-mannose, d-galactose, d-glucose, in addition to 2-keto-3-deoxyoctonate (KDO), glucosamine, 6-deoxyglucosamine (quinovosamine) and galactosamine uronic acid. The R. viridis O-antigens are clearly distinguishable from the l-glycero-d-mannoheptose containing O-antigens of R. palustris by the lack of this sugar (and of any other heptose) in the R. viridis LPS. The lipid moiety (lipid A) of the R. viridis O-antigen can be split off from the LPS by mild acid hydrolysis. Like lipid A from R. palustris, it differs remarkably from the well known lipid A of Enterobacteriaceae, in that d-glucosamine is replaced by a recently identified 2.3-diamino-2.3-dideoxyhexose in the R. viridis and R. palustris lipid A. Unlike enteric lipid A the R. viridis lipid A is phosphate-free and includes as the only fatty acid β-C₁₄OH which is exclusively amide-linked. All R. viridis strains belong to the same serotype so far as investigated, as shown by passive hemagglutination with the isolated O-antigens and rabbit antisera against heat-killed cells.     

Towards a comprehensive barcode library for arctic life - Ephemeroptera, Plecoptera, and Trichoptera of Churchill, Manitoba, Canada

Background

In order to understand the role of herbivores in trophic webs, it is essential to know what they feed on. Diet analysis is, however, a challenge in many small herbivores with a secretive life style. In this paper, we compare novel (high-throughput pyrosequencing) DNA barcoding technology for plant mixture with traditional microhistological method. We analysed stomach contents of two ecologically important subarctic vole species, Microtus oeconomus and Myodes rufocanus, with the two methods. DNA barcoding was conducted using the P6-loop of the chloroplast trnL (UAA) intron.

Results

Although the identified plant taxa in the diets matched relatively well between the two methods, DNA barcoding gave by far taxonomically more detailed results. Quantitative comparison of results was difficult, mainly due to low taxonomic resolution of the microhistological method, which also in part explained discrepancies between the methods. Other discrepancies were likely due to biases mostly in the microhistological analysis.

Conclusion

We conclude that DNA barcoding opens up for new possibilities in the study of plant-herbivore interactions, giving a detailed and relatively unbiased picture of food utilization of herbivores.     

New taxa and combinations in Malvastrum A. Gray (Malvaceae: Malveae)

The genusMalvastrum A. Gray is interpreted to include 22 taxa in 14 species. Seven taxa are here described as new, namely:M. americanum var.stellatum,M. tomentosum subsp.pautense,M. bicuspidatum subsp.campanulatum,M. bicuspidatum subsp.oaxacanum, M. bicuspidatum subsp.tumidum var.tumidum, M. bicuspidatum subsp.tumidum var.glabrum, andM. coromandelianum subsp.fryxellii. In addition, two new combinations are proposed, namely:M. tomentosum andM. coromandelianum subsp.capitato-spicatum.