Formation of body appendages during caudal regeneration in Platynereis dumerilii: adaptation of conserved molecular toolsets

Background: Platynereis and other polychaete annelids with homonomous segmentation are regarded to closely resemble ancestral forms of bilateria. The head region comprises the prostomium, the peristomium, a variable number of cephalized body segments and several appendages, like cirri, antennae and palps. The trunk of such polychaetes shows numerous, nearly identical segments. Each segment bears a parapodium with species-specific morphology on either side. The posterior end of the trunk features a segment proliferation zone and a terminal pygidium with the anus and anal cirri. The removal of a substantial part of the posterior trunk is by no means lethal. Cells at the site of injury dedifferentiate and proliferate forming a blastema to regenerate both the pygidium and the proliferation zone. The pygidium forms new anal cirri, and the proliferation zone generates new segments at a rapid pace. The formation of body appendages like the cirri and the segmental parapodia can thus be studied in the caudal regenerate of Platynereis within only a few days. Results: The development of body appendages in Platynereis is regulated by a network of genes common to polychaetes but also shared by distant taxa. We isolated DNA sequences from P. dumerilii of five genes known to be involved in appendage formation within other groups: Meis/homothorax, Pbx1/extradenticle, Dlx/Distal-less, decapentaplegic and specific protein 1/buttonhead. Analyses of expression patterns during caudal regeneration by in situ hybridization reveal striking similarities related to expression in arthropods and vertebrates. All genes exhibit transient expression during differentiation and growth of segments. As was shown previously in other phyla Pdu-Meis/hth and Pdu-Pbx1/exd are co-expressed, although the expression is not limited to the proximal part of the parapodia. Pdu-Dll is prominent in parapodia but upregulated in the anal cirri. No direct dependence concerning Pdu-Dll and Pdu-sp/btd expression is observed in Platynereis. Pdu-dpp shows an expression pattern not comparable to its expression in other taxa. Conclusions: The expression patterns observed suggest conserved roles of these genes during appendage formation across different clades, but the underlying mechanisms utilizing this toolset might not be identical. Some genes show broad expression along the proximodistal axis indicating a possible role in proximodistal patterning of body appendages. Other genes exhibit expression patterns limited to specific parts and tissues of the growing parapodia, thus presumably being involved in formation of taxon-specific morphological differences

Effects of sodium butyrate on DNA content, glutathione S-transferase activities, cell morphology and growth characteristics of rat liver nonparenchymal epithelial cells in vitro

The effects of sodium butyrate, which has been shown to act as a differentiation promoting agent in several different tumor cell lines, were studied in a rat liver nonparenchymal epithelial cell line. Exposure of these cells to 3.75 mM butyrate resulted in an inhibition of cell proliferation and, at the same time, an increase in cell diameter (2- to 6-fold) and size of the nuclei (∼2-fold) after 3 days in culture. Binucleated cells arose, comprising ∼12% of the cells investigated, and the number of cells with an abnormal set of chromosomes was increased. Intercellular communication, measured by dye transfer of Lucifer Yellow, was unchanged. From the various xenobiotic metabolizing enzyme activities measured, only those of glutathione S-transferases were significantly altered (increases of 4- to 9-fold) by butyrate treatment. These increases were mainly due to the predominant rise in the π class isoenzyme which is a well-known tumour marker in rat hepatocarcinogenesis. Thus, our results cannot be interpreted as being either due to promotion of differentiation or due to transformation. The state and type of cell under study has to be considered and investigations of further differentiation parameters are needed to obtain a deeper insight into the biological activity and the underlying mechanisms of cell state modifying agents like butyrat

Population structure and distribution patterns of the sibling mosquito apecies Culex pipiens and Culex torrentium (Diptera: Culicidae) reveal different evolutionary paths

Nowadays a number of endemic mosquito species are known to possess vector abilities for various diseases, as e.g. the sibling species Culex pipiens and Culex torrentium. Due to their morphological similarity, ecology, distribution and vector abilities, knowledge about these species' population structure is essential. Culicidae from 25 different sampling sites were collected from March till October 2012. All analyses were performed with aligned cox1 sequences with a total length of 658 bp. Population structure as well as distribution patterns of both species were analysed using molecular methods and different statistical tests like distance based redundancy analysis (dbDRA), analysis of molecular variances (AMOVA) or McDonald & Kreitman test and Tajima's D. Within both species, we could show a genetic variability among the cox1 fragment. The construction of haplotype networks revealed one dominating haplotype for Cx. pipiens, widely distributed within Germany and a more homogeneous pattern for Cx. torrentium. The low genetic differences within Cx. pipiens could be a result of an infection with Wolbachia which can induce a sweep through populations by passively taking the also maternally inherited mtDNA through the population, thereby reducing the mitochondrial diversity as an outcome of reproductive incompatibility. Pairwise population genetic differentiation (FST) ranged significantly from moderate to very great between populations of Cx. pipiens and Cx. torrentium. Analyses of molecular variances revealed for both species that the main genetic variability exists within the populations (Cx. pipiens [88.38%]; Cx. torrentium [66.54%]). Based on a distance based redundancy analysis geographical origin explained a small but significant part of the species' genetic variation. Overall, the results confirm that Cx. pipiens and Cx. torrentium underlie different factors regarding their mitochondrial differentiation, which could be a result of endosymbiosis, dispersal between nearly located populations or human introduction

Population Structure and Distribution Patterns of the Sibling Mosquito Species <i>Culex pipiens</i> and <i>Culex torrentium</i> (Diptera: Culicidae) Reveal Different Evolutionary Paths

<div><p>Nowadays a number of endemic mosquito species are known to possess vector abilities for various diseases, as e.g. the sibling species <i>Culex pipiens</i> and <i>Culex torrentium</i>. Due to their morphological similarity, ecology, distribution and vector abilities, knowledge about these species' population structure is essential. Culicidae from 25 different sampling sites were collected from March till October 2012. All analyses were performed with aligned cox1 sequences with a total length of 658 bp. Population structure as well as distribution patterns of both species were analysed using molecular methods and different statistical tests like distance based redundancy analysis (dbDRA), analysis of molecular variances (AMOVA) or McDonald & Kreitman test and Tajima's D. Within both species, we could show a genetic variability among the cox1 fragment. The construction of haplotype networks revealed one dominating haplotype for <i>Cx. pipiens</i>, widely distributed within Germany and a more homogeneous pattern for <i>Cx. torrentium</i>. The low genetic differences within <i>Cx. pipiens</i> could be a result of an infection with <i>Wolbachia</i> which can induce a sweep through populations by passively taking the also maternally inherited mtDNA through the population, thereby reducing the mitochondrial diversity as an outcome of reproductive incompatibility. Pairwise population genetic differentiation (F_ST) ranged significantly from moderate to very great between populations of <i>Cx. pipiens</i> and <i>Cx. torrentium</i>. Analyses of molecular variances revealed for both species that the main genetic variability exists within the populations (<i>Cx. pipiens</i> [88.38%]; <i>Cx. torrentium</i> [66.54%]). Based on a distance based redundancy analysis geographical origin explained a small but significant part of the species' genetic variation. Overall, the results confirm that <i>Cx. pipiens</i> and <i>Cx. torrentium</i> underlie different factors regarding their mitochondrial differentiation, which could be a result of endosymbiosis, dispersal between nearly located populations or human introduction.</p></div

Sampling localities of <i>Culex torrentium</i> across Germany with significant different population pairwise F_ST values.

<p>Significant F_ST values were grouped into the four following categories: very great population differentiation (red lines), great population differentiation (yellow lines), moderate population differentiation (green lines) and low population differentiation (purple lines) <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0102158#pone.0102158-Balloux1" target="_blank">[67]</a>. Pictured are all sampling points listed in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0102158#pone-0102158-t005" target="_blank">Table 5</a> with a summary of their haplotypes. There were no significant moderate or low F_ST values. Map was created with ArcMap 10.1.</p

AMOVA group structure of <i>Culex pipiens</i> and <i>Culex torrentium</i>.

<p>Group structures are based on pairwise F_ST's of <i>Culex pipiens</i> and <i>Culex torrentium</i>.</p

Distribution of <i>Culex torrentium</i> (white) and <i>Culex pipiens</i> (grey) in Germany (A) and the Hessian Rhine-Main area (B).

<p>Small circles in Figure 1A (excluding the circles for FFM, BV, AS and GR) indicate that only one of the two species was detected at this specific locality. Pie charts indicate the ratio of the two detected species at this locality. The sizes of the pie chart and the circles do not relate to the number of investigated individuals (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0102158#pone-0102158-t001" target="_blank">Table 1</a>). A: Overview of the sampling localities across Germany. Abbreviations: AS = Altenstadt, BV = Bad Vilbel, MF = Berlin-Marienfelde, BI = Bielefeld, BL = Bad Lippspringe, DB = Duisburg, DK = Dresden-Klotzsche, EW = Eberswalde, FFM = Frankfurt/Main (four different localities: Bornheim (FB), Bockenheim (KS), Sachsenhausen (FS) and Ostend (FZ)), FT = Fuldatal, GR = Gründau-Rothenbergen, HU = Husum, KL = Klein Linden, LE = Lebus, LL = Langenlehsten, MG = Mönchengladbach, MÜ = Müncheberg, RI = Rietschen, ST = Stralsund and WI = Wismar. B: Detailed view of the Rhine-Main area with Höchst a.d.N. (A1), Eichen (AS2), Heldenbergen (AS3), Klein Linden. Map was created with ArcMap 10.1.</p

Sampling localities of <i>Culex pipiens</i> across Germany with significant different population pairwise F_ST values.

<p>Significant different pairwise F_ST values between populations are indicated using different line colors. Significant F_ST values were grouped into the four following categories: very great population differentiation (red lines), great population differentiation (yellow lines), moderate population differentiation (green lines) and low population differentiation (purple lines) <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0102158#pone.0102158-Balloux1" target="_blank">[67]</a>. Pictured are all sampling points listed in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0102158#pone-0102158-t004" target="_blank">Table 4</a> with a summary of their haplotypes. Map was created with ArcMap 10.1.</p

Sampling localities in Germany with abbreviations and number of sequences and detected haplotypes at each locality.

<p>Sampling localities in Germany with abbreviations and number of sequences and detected haplotypes at each locality.</p