Remodeling of the Musculature during Sexual Maturation.

Background: The external transformations associated with sexual maturation in (Audouin and Milne Edwards) are well studied, whereas the internal changes along the body axis have not been systematically analyzed. Therefore, we examined muscle morphology in body regions located anterior or posterior to the prospective atokous/epitokous border to generate a structural basis for internal transformations.

Results: All dorsal and ventral longitudinal muscles were significantly reduced in size and density after sexual maturation and strongly atrophied, with the greatest decrease in the anterior segments of females.

Expression of katanin p80 in human spermatogenesis.

Objective: To define the stage-by-stage expression of KATNB1 during human spermatogenesis.

Design: Gene expression analysis, histologic and immunohistochemical evaluation.

Setting: University research laboratories and andrological clinic.

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.

Cholinergic urethral brush cells are widespread throughout placental mammals.

We previously identified a population of cholinergic epithelial cells in murine, human and rat urethrae that exhibits a structural marker of brush cells (villin) and expresses components of the canonical taste transduction signaling cascade (α-gustducin, phospholipase Cβ2 (PLCβ2), transient receptor potential cation channel melanostatin 5 (TRPM5)). These cells serve as sentinels, monitoring the chemical composition of the luminal content for potentially hazardous compounds such as bacteria, and initiate protective reflexes counteracting further ingression. In order to elucidate cross-species conservation of the urethral chemosensory pathway we investigated the occurrence and molecular make-up of urethral brush cells in placental mammals.

Population structure and distribution patterns of the sibling mosquito species 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.

Maternal inheritance of twist and analysis of MAPK activation in embryos of the polychaete annelid Platynereis dumerilii.

In this study, we aimed to identify molecular mechanisms involved in the specification of the 4d (mesentoblast) lineage in Platynereis dumerilii. We employ RT-PCR and in situ hybridization against the Platynereis dumerilii twist homolog (Pdu-twist) to reveal mesodermal specification within this lineage. We show that Pdu-twist mRNA is already maternally distributed.

Identification and characterization of a twist ortholog in the polychaete annelid Platynereis dumerilii reveals mesodermal expression of Pdu-twist.

The basic helix-loop-helix transcription factor twist plays a key role during mesoderm development in Bilateria. In this study, we identified a twist ortholog in the polychaete annelid Platynereis dumerilii and analyze its expression during larval development, postlarval growth up to the adult stage, and caudal regeneration after amputation of posterior segments. At late larval stages, Pdu-twist is expressed in the mesodermal anlagen and in developing muscles.

Diversity of Culex torrentium Martini, 1925 - a potential vector of arboviruses and filaria in Europe.

Culex torrentium is one of the most common mosquito species in Germany. Due to its sympatric occurrence as well as its similar morphological and ecological characteristics, it has often been confused with another common species, Culex pipiens. Both species are known to be potential vectors for different arboviruses (not only in Germany) with C.

Activation of Hox genes during caudal regeneration of the polychaete annelid Platynereis dumerilii.

The capability of regenerating posterior segments and pygidial structures is ancestral for annelids and has been lost only a few times within this phylum. As one of the three major segmented taxa, annelids enable us to monitor reconstruction of lost tissues and organs. During regeneration, regional identities have to be imprinted onto the newly formed segments.

Intervertebral disc regeneration: influence of growth factors on differentiation of human mesenchymal stem cells (hMSC).

Introduction: One common cause of disability in modern society is low back pain. The main reason for this pain is the degeneration of the intervertebral disc (IVD), particularly of the nucleus pulposus (NP). For the early degeneration stage, a cell-based therapy could constitute a minimally invasive method of treatment.

Clonal domains in postlarval Platynereis dumerilii (Annelida: Polychaeta).

Following an enzymatic procedure for softening the egg envelope, blastomeres in the embryo of the polychaete Platynereis dumerilii were injected with TRITC-dextran. Injection was successful in the following blastomeres: AB, CD, A, B, C, D, 1a-1d, 1A-1D, 4d, and 4d(1). The distribution of fluorescent label was recorded by confocal laser scanning microscopy of young, three-segmented worms after 3 or 4 days of development, in some cases also in 1-day-old trochophore larvae.

Ciliary photoreceptors with a vertebrate-type opsin in an invertebrate brain.

For vision, insect and vertebrate eyes use rhabdomeric and ciliary photoreceptor cells, respectively. These cells show distinct architecture and transduce the light signal by different phototransductory cascades. In the marine rag-worm Platynereis, we find both cell types: rhabdomeric photoreceptor cells in the eyes and ciliary photoreceptor cells in the brain.

The polychaete Platynereis dumerilii (Annelida): a laboratory animal with spiralian cleavage, lifelong segment proliferation and a mixed benthic/pelagic life cycle.

Platynereis dumerilii, a marine polychaetous annelid with indirect development, can be continuously bred in the laboratory. Here, we describe its spectacular reproduction and development and address a number of open research problems. Oogenesis is easily studied because the oocytes grow while floating in the coelom.

Arthropod-like expression patterns of engrailed and wingless in the annelid Platynereis dumerilii suggest a role in segment formation.

The origin of animal segmentation, the periodic repetition of anatomical structures along the anteroposterior axis, is a long-standing issue that has been recently revived by comparative developmental genetics. In particular, a similar extensive morphological segmentation (or metamerism) is commonly recognized in annelids and arthropods. Mostly based on this supposedly homologous segmentation, these phyla have been united for a long time into the clade Articulata.

Development of pigment-cup eyes in the polychaete Platynereis dumerilii and evolutionary conservation of larval eyes in Bilateria.

The role of Pax6 in eye development in insects and vertebrates supports the view that their eyes evolved from simple pigment-cup ocelli present in their last common ancestors (Urbilateria). The cerebral eyes in errant polychaetes represent prototype invertebrate pigment-cup ocelli and thus resemble the presumed ancestral eyes. We have analysed expression of conserved eye specification genes in the early development of larval and adult pigment-cup eyes in Platynereis dumerilii (Polychaeta, Annelida, Lophotrochozoa).

Competence of blastomeres for the expression of molecular tissue markers is acquired by diverse mechanisms in the embryo of Platynereis (Annelida).

This paper is devoted to the role of cell divisions for the establishment of histospecificity in the embryo of the spiralian, Platynereis dumerilii (Annelida). We have incubated successive cleavage stages in cytochalasin B (CCB) and observed whether the cells thereafter were able to acquire the competence for expressing histospecific antigens of larval gland cells (labelled by the monoclonal antibody OI64) and of neural components of the ventral nerve cord (labelled by mAb OI7 or by testing acety1cholinesterase activity), respectively. Incubation in CCB results in permanent cleavage arrest, but does not necessarily interfere with biochemical differentiation of such markers.

Molecular specification of cell lines in the embryo of Platynereis (Annelida).

In this study we describe the site and moment of histospecific differentiation in developmental stages of the annelid Platynereis dumerilii by use of biochemical markers. The monoclonal antibody (mab) OI7 and uncloned hybridoma supernatants (pAb's) OI8, OI10, OI46 and OI69 recognize neural antigens that appear asynchronously during development. By an enzymatic test, acetylcholinesterase (AChE) was found specific for nervous tissue as well.

A morphometric comparison of dissimilar early development in sibling species of Platynereis (Annelida, Polychaeta).

Early development of Platynereis massiliensis was studied in serial sections of fixed embryos and in living or fixed embryos whose nuclei had been made visible with a fluorescent label. The unfertilized egg is an ellipsoid with three axes of differing length. The longest axis corresponds to the dorsoventral axis of the developing embryo.

Experimental change of cytoplasmic composition can convert determination of blastomeres inPlatynereis dumerilii (Annelida, Polychaeta).

Early development ofPlatynereis dumerilii is characterized by an extremely constant cleavage pattern in which the volumes and cytoplasmic contents of the blastomeres show remarkably little variability (Dorresteijn 1990). In order to test the necessity of a precise partitioning of the cytoplasm, we have stratified the ooplasm by mild centrifugation (10 min at 300 g) after completion of meiosis but before first cleavage. The cytoplasm of the zygote stratifies randomly with respect to the pre-existing animal-vegetal axis, but first cleavage follows the animal-vegetal axis dividing the plasm before it has rearranged to its normal distribution.

Quantitative analysis of cellular differentiation during early embryogenesis ofPlatynereis dumerilii.

As in many spiralian embryos with unequal cleavage, cleavage inPlatynereis follows an invariant pattern. Preceding each cleavage the cytoplasm is reorganized, allowing the spiral cleavage mode to produce cells with different cytoplasmic composition. The fertilized egg undergoes a dramatic ooplasmic segregation after the completion of the cortical reaction.

A correlative study of experimentally changed first cleavage and Janus development in the trunk of Platynereis dumerilii (Annelida, Polychaeta).

Among zygotes of Platynereis dumerilii treated with cytochalasin B (CCB) prior to first cleavage, a wide variety of developmental effects were observed. One effect is a delay in the first cleavage. Treated embryos may skip the first or even more than one cleavage cycle and become multinucleated.

Dye-coupling between blastomeres in early embryos ofPatella vulgata (mollusca, gastropoda): Its relevance for cell determination.

During the early development of the molluscPatella, the dorsoventral axis is established after the fifth cleavage due to direct interaction between the animal micromeres and one of the vegetal macromeres. This vegetal macromere is thereby induced to become the mesentoblast mother cell (3D). In this study we have examined intercellular communication in earlyPatella embryos by monitoring the transfer of the fluorescent dye, Lucifer Yellow, upon iontophoretic injection into blastomeres between the second and sixth cleavage.