Conservation of MAP kinase activity and MSP genes in parthenogenetic nematodes

<p>Abstract</p> <p>Background</p> <p>MAP (mitogen-activated protein) kinase activation is a prerequisite for oocyte maturation, ovulation and fertilisation in many animals. In the hermaphroditic nematode <it>Caenorhabditis elegans</it>, an MSP (major sperm protein) dependent pathway is utilised for MAP kinase activation and successive oocyte maturation with extracellular MSP released from sperm acting as activator. How oocyte-to-embryo transition is triggered in parthenogenetic nematode species that lack sperm, is not known.</p> <p>Results</p> <p>We investigated two key elements of oocyte-to-embryo transition, MSP expression and MAP kinase signaling, in two parthenogenetic nematodes and their close hermaphroditic relatives. While activated MAP kinase is present in all analysed nematodes irrespective of the reproductive mode, MSP expression differs. In contrast to hermaphroditic or bisexual species, we do not find MSP expression at the protein level in parthenogenetic nematodes. However, genomic sequence analysis indicates that functional MSP genes are present in several parthenogenetic species.</p> <p>Conclusions</p> <p>We present three alternative interpretations to explain our findings. (1) MSP has lost its function as a trigger of MAP kinase activation and is not expressed in parthenogenetic nematodes. Activation of the MAP kinase pathway is achieved by another, unknown mechanism. Functional MSP genes are required for occasionally emerging males found in some parthenogenetic species. (2) Because of long-term disadvantages, parthenogenesis is of recent origin. MSP genes remained intact during this short intervall although they are useless. As in the first scenario, an unknown mechanism is responsible for MAP kinase activation. (3) The molecular machinery regulating oocyte-to-embryo transition in parthenogenetic nematodes is conserved with respect to <it>C. elegans</it>, thus requiring intact MSP genes. However, MSP expression has been shifted to non-sperm cells and is reduced below the detection limits, but is still sufficient to trigger MAP kinase activation and embryogenesis.</p

Methode zur Erfassung und Bewertung der FFH-Waldlebensraumtypen im Rahmen der dritten Bundeswaldinventur (BWI-2012)

Art. 11 der FFH-Richtlinie fordert die Durchführung eines flächendeckenden Monitorings u. a. des Erhaltungszustands der Lebensraumtypen (LRTen) in den Mitgliedsstaaten. In Deutschland hat die Bund-/Länderarbeitsgemeinschaft Naturschutz, Landschaftspflege und Erholung (LANA) die Forstseite (FCK) gebeten, für den Nationalen FFH-Bericht die Bundeswaldinventur um eine Methodik zur Erfassung / Bewertung verbreiteter Waldlebensraumtypen (WLRTen) zu ergänzen und damit ressortübergreifende Synergieeffekte zu nutzen. Das hier beschriebene Konzept stellt eine Methode zur Erfassung und Bewertung großräumig oder häufig vorkommender FFH-WLRTen im Rahmen der dritten Bundeswaldinventur (BWI-2012) vor. Es berücksichtigt die Vorgaben der EU und des LANA-FCK-Papiers aus dem Jahr 2004. Das bundesweite FFH-Monitoring und der Nationale FFH-Bericht sehen Aussagen zum Erhaltungszustand jedes WLRTs auf Ebene der biogeographischen Regionen in Deutschland vor, nicht jedoch Aussagen auf Landesebene oder in Bezug auf noch kleinere Teilgebiete wie beispielsweise einzelne FFH-Gebiete. Die Länder können durch Umsetzung des hier beschriebenen Konzepts ein bestehendes Monitoring-System nutzen und damit ihren notwendigen Beitrag im Bereich der WLRTen zur deutschen FFH-Berichtspflicht erbringen. Die Methodik wurde von FCK und LANA angenommen und von Bund und Ländern in das BWI-Verfahren eingearbeitet. Die Erhebungsergebnisse sind in den nationalen FFH-Bericht 2013 eingeflossen. Im Nachgang zur BWI-2012 wurde die Beschreibung der Methodik aktualisiert.Article 11 of the FFH Directive mandates the implementation of nationwide monitoring, inter alia, of the conservation status of habitat types in the Member States. In Germany, the German Federal Government/Länder (federal states) Working Group on Nature Conservation, Landscape Management and Recreation (LANA) asked the Forest Directors' Conference (FCK) to supplement the National Forest Inventory with a methodology of recording and assessing prevalent forest habitat types for the national FFH report, thus making use of interdepartmental synergy effects. The scheme described herein presents a methodology for recording and assessing common or widespread FFH forest habitat types within the scope of the third National Forest Inventory (NFI 2012). In doing so, it takes into account the requirements of the EU and the LANA-FCK paper of 2004. While the nationwide FFH monitoring and the National FFH Report provide for conclusions concerning the conservation status of each forest habitat type at the level of the biogeographic regions in Germany as a whole, they do not allow conclusions at the level of the Länder or with respect to even smaller subareas such as individual FFH areas, for example. By implementing the scheme described herein, the Länder can use the monitoring system in place for their necessary contribution to the German FFH reporting obligation on forest habitat types. The elaborated methodology was adopted by the FCK and LANA and incorporated in the NFI procedure by the Federal Government and the Länder. The survey outcome has been incorporated into the 2013 national FFH report. As a follow-up to the NFI-2012, the description of the methodology has been updated

Tree species atlas of the third national forest inventory (BWI 2012)

Die deutsche Bundeswaldinventur (BWI) ist eine systematische Stichprobeninventur, die im 4 km x 4 km-Grundnetz mit regionalen Netzverdichtungen die Waldverhältnisse in ganz Deutschland aufzeigt. Insgesamt 51 Baumarten werden in der BWI erfasst. Der vorliegende Baumartenatlas gibt an, wie standortgerecht die 31 wichtigsten Baumarten in Deutschland sind. Eine Baumart wird je nach vorhandener natürlicher Waldgesellschaft als eine Pionierbaumart, eine akzessorische oder obligatorische Klimaxbaumart bzw. als eine Baumart außerhalb des natürlichen Verbreitungsgebiets kategorisiert. Die Kategorisierung ist bedeutsam für die Ableitung des Naturnähegrads der Baumartenzusammensetzung in der BWI.The National Forest Inventory (BWI) records the forest conditions in Germany in a systematic sample inventory on the basis of a 4 km x 4 km reference grid with regional grid refinements. The BWI distinguishes a total of 51 tree species or tree species groups. This tree atlas informs about the distribution and the ecological relevance of the 31 most important tree species in Germany in the natural forest community of a sample point. It separately outlines the categories of pioneer tree species, accessory or mandatory climax tree species or tree species outside the natural distribution area. [...] The categorization is, for instance, the basis for determining the naturalness of the tree species composition in the BWI

The genome of Romanomermis culicivorax:revealing fundamental changes in the core developmental genetic toolkit in Nematoda

Background: The genetics of development in the nematode Caenorhabditis elegans has been described in exquisite detail. The phylum Nematoda has two classes: Chromadorea (which includes C. elegans) and the Enoplea. While the development of many chromadorean species resembles closely that of C. elegans, enoplean nematodes show markedly different patterns of early cell division and cell fate assignment. Embryogenesis of the enoplean Romanomermis culicivorax has been studied in detail, but the genetic circuitry underpinning development in this species has not been explored. Results: We generated a draft genome for R. culicivorax and compared its gene content with that of C. elegans, a second enoplean, the vertebrate parasite Trichinella spiralis, and a representative arthropod, Tribolium castaneum. This comparison revealed that R. culicivorax has retained components of the conserved ecdysozoan developmental gene toolkit lost in C. elegans. T. spiralis has independently lost even more of this toolkit than has C. elegans. However, the C. elegans toolkit is not simply depauperate, as many novel genes essential for embryogenesis in C. elegans are not found in, or have only extremely divergent homologues in R. culicivorax and T. spiralis. Our data imply fundamental differences in the genetic programmes not only for early cell specification but also others such as vulva formation and sex determination. Conclusions: Despite the apparent morphological conservatism, major differences in the molecular logic of development have evolved within the phylum Nematoda. R. culicivorax serves as a tractable system to contrast C. elegans and understand how divergent genomic and thus regulatory backgrounds nevertheless generate a conserved phenotype. The R. culicivorax draft genome will promote use of this species as a research model

Operon conservation and the evolution of trans-splicing in the phylum Nematoda

The nematode Caenorhabditis elegans is unique among model animals in that many of its genes are cotranscribed as polycistronic pre-mRNAs from operons. The mechanism by which these operonic transcripts are resolved into mature mRNAs includes trans-splicing to a family of SL2-like spliced leader exons. SL2-like spliced leaders are distinct from SL1, the major spliced leader in C. elegans and other nematode species. We surveyed five additional nematode species, representing three of the five major clades of the phylum Nematoda, for the presence of operons and the use of trans-spliced leaders in resolution of polycistronic pre-mRNAs. Conserved operons were found in Pristionchus pacificus, Nippostrongylus brasiliensis, Strongyloides ratti, Brugia malayi, and Ascaris suum. In nematodes closely related to the rhabditine C. elegans, a related family of SL2-like spliced leaders is used for operonic transcript resolution. However, in the tylenchine S. ratti operonic transcripts are resolved using a family of spliced leaders related to SL1. Non-operonic genes in S. ratti may also receive these SL1 variants. In the spirurine nematodes B. malayi and A. suum operonic transcripts are resolved using SL1. Mapping these phenotypes onto the robust molecular phylogeny for the Nematoda suggests that operons evolved before SL2-like spliced leaders, which are an evolutionary invention of the rhabditine lineage

Silencing of PTK7 in Colon Cancer Cells: Caspase-10-Dependent Apoptosis via Mitochondrial Pathway

Protein tyrosine kinase-7 (PTK7) is a catalytically inactive receptor tyrosine kinase (RTK). PTK7 is upregulated in many common human cancers, including colon cancer, lung cancer, gastric cancer and acute myeloid leukemia. The reason for this up-regulation is not yet known. To explore the functional role of PTK7, the expression of PTK7 in HCT 116 cells was examined using small interference (siRNA)-mediated gene silencing. Following transfection, the siRNA successfully suppressed PTK7 mRNA and protein expression. Knocking down of PTK7 in HCT 116 cells inhibited cell proliferation compared to control groups and induced apoptosis. Furthermore, this apoptosis was characterized by decreased mitochondrial membrane potential and activation of caspase-9 and -10. Addition of a caspase-10 inhibitor totally blocked this apoptosis, suggesting that caspase-10 may play a critical role in PTK7-knockdown-induced apoptosis, downstream of mitochondria. These observations may indicate a role for PTK7 in cell proliferation and cell apoptosis and may provide a potential therapeutic pathway for the treatment of a variety of cancers

Structure-Function Analysis of STRUBBELIG, an Arabidopsis Atypical Receptor-Like Kinase Involved in Tissue Morphogenesis

Tissue morphogenesis in plants requires the coordination of cellular behavior across clonally distinct histogenic layers. The underlying signaling mechanisms are presently being unraveled and are known to include the cell surface leucine-rich repeat receptor-like kinase STRUBBELIG in Arabidopsis. To understand better its mode of action an extensive structure-function analysis of STRUBBELIG was performed. The phenotypes of 20 EMS and T-DNA-induced strubbelig alleles were assessed and homology modeling was applied to rationalize their possible effects on STRUBBELIG protein structure. The analysis was complemented by phenotypic, cell biological, and pharmacological investigations of a strubbelig null allele carrying genomic rescue constructs encoding fusions between various mutated STRUBBELIG proteins and GFP. The results indicate that STRUBBELIG accepts quite some sequence variation, reveal the biological importance for the STRUBBELIG N-capping domain, and reinforce the notion that kinase activity is not essential for its function in vivo. Furthermore, individual protein domains of STRUBBELIG cannot be related to specific STRUBBELIG-dependent biological processes suggesting that process specificity is mediated by factors acting together with or downstream of STRUBBELIG. In addition, the evidence indicates that biogenesis of a functional STRUBBELIG receptor is subject to endoplasmic reticulum-mediated quality control, and that an MG132-sensitive process regulates its stability. Finally, STRUBBELIG and the receptor-like kinase gene ERECTA interact synergistically in the control of internode length. The data provide genetic and molecular insight into how STRUBBELIG regulates intercellular communication in tissue morphogenesis

DETORQUEO, QUIRKY, and ZERZAUST Represent Novel Components Involved in Organ Development Mediated by the Receptor-Like Kinase STRUBBELIG in Arabidopsis thaliana

Intercellular signaling plays an important role in controlling cellular behavior in apical meristems and developing organs in plants. One prominent example in Arabidopsis is the regulation of floral organ shape, ovule integument morphogenesis, the cell division plane, and root hair patterning by the leucine-rich repeat receptor-like kinase STRUBBELIG (SUB). Interestingly, kinase activity of SUB is not essential for its in vivo function, indicating that SUB may be an atypical or inactive receptor-like kinase. Since little is known about signaling by atypical receptor-like kinases, we used forward genetics to identify genes that potentially function in SUB-dependent processes and found recessive mutations in three genes that result in a sub-like phenotype. Plants with a defect in DETORQEO (DOQ), QUIRKY (QKY), and ZERZAUST (ZET) show corresponding defects in outer integument development, floral organ shape, and stem twisting. The mutants also show sub-like cellular defects in the floral meristem and in root hair patterning. Thus, SUB, DOQ, QKY, and ZET define the STRUBBELIG-LIKE MUTANT (SLM) class of genes. Molecular cloning of QKY identified a putative transmembrane protein carrying four C2 domains, suggesting that QKY may function in membrane trafficking in a Ca2+-dependent fashion. Morphological analysis of single and all pair-wise double-mutant combinations indicated that SLM genes have overlapping, but also distinct, functions in plant organogenesis. This notion was supported by a systematic comparison of whole-genome transcript profiles during floral development, which molecularly defined common and distinct sets of affected processes in slm mutants. Further analysis indicated that many SLM-responsive genes have functions in cell wall biology, hormone signaling, and various stress responses. Taken together, our data suggest that DOQ, QKY, and ZET contribute to SUB-dependent organogenesis and shed light on the mechanisms, which are dependent on signaling through the atypical receptor-like kinase SUB