Big ‘antlers’ are favoured: female choice in stalk-eyed flies (Diptera,Insecta), field collected harems and laboratory experiments

Summary Cyrtodiopsis whitei (Diopsidae) from Malaysia is one of the stalk-eyed flies which show a marked sexual dimorphism ofeye spans. The particularly long eye stalks of male flies are to be regarded as an epigamic feature. Field observations show the males' eye spans to be correlated with the possession of a harem and with that harem's size. The question whether such a harem is acquired by male competition only, or whether female choice plays a part, is solved in female preference tests, offering dummy males of different eye spans for choice. Optical clues are found to be the relevant stimuli.     

Beiträge zur Verbreitungsgeschichte der GattungTaraxacum im zentral- und nordostmediterranen Raum

Zusammenfassung Diploidie, reliktäres Vorkommen und ziemlich genaue Übereinstimmung des Areals mit paläogeographischen Landkarten des Mittelmeergebietes und der östlich angrenzenden Länder weisen die kurzschnäbeligenTaraxaca als alte Typen — wahrscheinlich Tertiärrelikte — aus. Ein engerer Zusammenhang der übrigen, offenbar meist polyploiden mediterranenTaraxaca mit den alten Typen sowie dieser beiden mit den mittel- und nordeuropäischenTaraxacum-Arten scheint nicht gegeben zu sein.

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Summary Diploidy, relic occurence and rather exact correspondence of their areals with paleogeographic maps of the mediterranean area and of adjacent territories mark the shortly rostratedTaraxaca as ancient types, probably relics. These ancient types are neither closely related to the younger mediterranean polyploids, nor to the middle- and north-europeanTaraxacum species, just as nearer connections between the young mediterranean types and the young middle- and north-europeanTaraxacum species are not probable.

     

Das Inselorgan des Crossopterygiers Latimeria chalumnae J. L. B. Smith

Zusammenfassung Das Pankreas und der Fettkörper von Latimeria chalumnae, dem einzigen rezenten Crossopterygier aus der Klasse der Coelacanthes, werden in ihrer Lagebeziehung zu Magen, Darm und Milz beschrieben. Das von Millot und Anthony (1958) als Pankreas geschilderte Organ wird histologisch als Fettkörper identifiziert. Der exokrine Pankreasanteil besteht, ähnlich wie bei anderen niederen Wirbeltieren, aus einem tubulösen System exkretorischer Zellen. Das Inselorgan ist mit dem Gangsystem verbunden. Mit der Aldehydfuchsin Ponceau de Xylidine-Färbung lassen sich A- und B-Zellen, mit der Versilberung nach Hellman und Hellerström (1960) Silberzellen darstellen. Geschwollene Zellen werden als Fixationsartefakt nach Formolfixierung betrachtet. B-Zellknospen an den Gängen werden als erste phylogenetische Ansätze zu einer Dissemination des Inselorgans in das exokrine Parenchym hinein gedeutet. Zellen zwischen den exokrinen Tubuli werden beschrieben. Die Befunde werden mit den Ergebnissen am Pankreas niederer Wirbeltiere und Säuger verglichen.

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Summary The topographical anatomy of the pancreas and the fat-body of Latimeria chalumnae, the only living Crossopterygian of the suborder of Coelacanths, is described. The organ, which was considered by Millot and Anthony (1958) to be the pancreas, has been histologically identified as a fat-body. The exocrine part of the pancreas consists of a tubulous system of exocrine cells, which are similar to those of lower vertebrates. The islet-organ is connected to the ductsystem. The aldehydfuchsin Ponceau de Xylidine-staining makes it possible to demonstrate - and -cells, the argyrophil reaction according to Hellman and Hellerström (1960) silvercells. Swollen cells are thought to be fixation artefacts due to formalin-fixation. -cellbuds, which are attached to the ducts, are regarded as the first phylogenetic beginning of dissemination of the islet-organ into the exocrine tissue. Cells between the exocrine tubules are described. The findings are compared with the results of the investigations of the pancreas of lower vertebrates and mammals.

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Herrn Dr. G. v. Wahlert, Forschungsstelle für Ichthylogie in Ludwigsburg, danke ich für die freundliche Überlassung des Untersuchungsmaterials.     

Ceramide levels in blood plasma correlate with major depressive disorder severity and its neutralization abrogates depressive behavior in mice

Major depressive disorder (MDD) is a severe disease of unknown pathogenesis that will affect ∼10% of people during their lifetime. Therapy for MDD requires prolonged treatment and often fails, predicating a need for novel treatment strategies. Here, we report increased ceramide levels in the blood plasma of MDD patients and in murine stress-induced models of MDD. These blood plasma ceramide levels correlated with the severity of MDD in human patients and were independent of age, sex, or body mass index. In addition, intravenous injection of anti-ceramide antibodies or neutral ceramidase rapidly abrogated stress-induced MDD, and intravenous injection of blood plasma from mice with MDD induced depression-like behavior in untreated mice, which was abrogated by ex vivo preincubation of the plasma with anti-ceramide antibodies or ceramidase. Mechanistically, we demonstrate that ceramide accumulated in endothelial cells of the hippocampus of stressed mice, evidenced by the quantitative measurement of ceramide in purified hippocampus endothelial cells. We found ceramide inhibited the activity of phospholipase D (PLD) in endothelial cells in vitro and in the hippocampus in vivo and thereby decreased phosphatidic acid in the hippocampus. Finally, we show intravenous injection of PLD or phosphatidic acid abrogated MDD, indicating the significance of this pathway in MDD pathogenesis. Our data indicate that ceramide controls PLD activity and phosphatidic acid formation in hippocampal endothelial cells and thereby mediates MDD. We propose that neutralization of plasma ceramide could represent a rapid-acting targeted treatment for MDD.     

Independent recruitment of a flavin-dependent monooxygenase for safe accumulation of sequestered pyrrolizidine alkaloids in grasshoppers and moths

Several insect lineages have developed diverse strategies to sequester toxic pyrrolizidine alkaloids from food-plants for their own defense. Here, we show that in two highly divergent insect taxa, the hemimetabolous grasshoppers and the holometabolous butterflies, an almost identical strategy evolved independently for safe accumulation of pyrrolizidine alkaloids. This strategy involves a pyrrolizidine alkaloid N-oxygenase that transfers the pyrrolizidine alkaloids to their respective N-oxide, enabling the insects to avoid high concentrations of toxic pyrrolizidine alkaloids in the hemolymph. We have identified a pyrrolizidine alkaloid N-oxygenase, which is a flavin-dependent monooxygenase, of the grasshopper Zonocerus variegatus. After heterologous expression in E. coli, this enzyme shows high specificity for pyrrolizidine alkaloids of various structural types and for the tropane alkaloid atropine as substrates, a property that has been described previously for a pyrrolizidine alkaloid N-oxygenase of the arctiid moth Grammia geneura. Phylogenetic analyses of insect flavin-dependent monooxygenase sequences suggest that independent gene duplication events preceded the establishment of this specific enzyme in the lineages of the grasshoppers and of arctiid moths. Two further flavin-dependent monooxygenase sequences have been identified from Z. variegatus sharing amino acid identities of approximately 78% to the pyrrolizidine alkaloid N-oxygenase. After heterologous expression, both enzymes are also able to catalyze the N-oxygenation of pyrrolizidine alkaloids, albeit with a 400-fold lower specific activity. With respect to the high sequence identity between the three Z. variegatus sequences this ability to N-oxygenize pyrrolizidine alkaloids is interpreted as a relict of a former bifunctional ancestor gene of which one of the gene copies optimized this activity for the specific adaptation to pyrrolizidine alkaloid containing food plants.     

Presymptomatic risk assessment for chronic non-communicable diseases

The prevalence of common chronic non-communicable diseases (CNCDs) far overshadows the prevalence of both monogenic and infectious diseases combined. All CNCDs, also called complex genetic diseases, have a heritable genetic component that can be used for pre-symptomatic risk assessment. Common single nucleotide polymorphisms (SNPs) that tag risk haplotypes across the genome currently account for a non-trivial portion of the germ-line genetic risk and we will likely continue to identify the remaining missing heritability in the form of rare variants, copy number variants and epigenetic modifications. Here, we describe a novel measure for calculating the lifetime risk of a disease, called the genetic composite index (GCI), and demonstrate its predictive value as a clinical classifier. The GCI only considers summary statistics of the effects of genetic variation and hence does not require the results of large-scale studies simultaneously assessing multiple risk factors. Combining GCI scores with environmental risk information provides an additional tool for clinical decision-making. The GCI can be populated with heritable risk information of any type, and thus represents a framework for CNCD pre-symptomatic risk assessment that can be populated as additional risk information is identified through next-generation technologies.     

Stem-like cells in human hepatoblastoma.

Hepatoblastoma is a pediatric liver tumor with epithelial components resembling embryonal and fetal liver cells. The existence of teratoid hepatoblastoma suggests the presence of stem cells in hepatoblastoma. The aim of this study was to analyze the expression of stem cell markers in hepatoblastomas. We studied specimens from 10 hepatoblastomas. Five of the hepatoblastomas were of epithelial and five of mixed type. Immunohistochemistry (IHC) for the stem cell markers CD34, Thy1, c-kit, and the hepatic or biliary lineage markers CK-18, OCH, CK-7, and CD56 was performed. Double IHC for stem cell and lineage markers was used to identify putative liver stem cells. The different markers showed distinct distributions on the tumor cells. Cells in atypical ducts were found to express simultaneously stem cell markers and hepatocytic or biliary lineage markers. Other cells in connective tissue showed c-kit expression, but not hepatic or biliary marker expression. The data show the presence of different cell populations bearing stem cell markers in human hepatoblastoma. Ductal cells co-expressing stem cell markers and hepatic lineage markers phenotypically resemble hepatic stem-like cells. These findings support the thesis that stem cells play a role in the histogenesis of hepatoblastoma.     

ER–mitochondria contacts control surface glycan expression and sensitivity to killer lymphocytes in glioma stem‐like cells

Glioblastoma is a highly heterogeneous aggressive primary brain tumor, with the glioma stem‐like cells (GSC) being more sensitive to cytotoxic lymphocyte‐mediated killing than glioma differentiated cells (GDC). However, the mechanism behind this higher sensitivity is unclear. Here, we found that the mitochondrial morphology of GSCs modulates the ER–mitochondria contacts that regulate the surface expression of sialylated glycans and their recognition by cytotoxic T lymphocytes and natural killer cells. GSCs displayed diminished ER–mitochondria contacts compared to GDCs. Forced ER–mitochondria contacts in GSCs increased their cell surface expression of sialylated glycans and reduced their susceptibility to cytotoxic lymphocytes. Therefore, mitochondrial morphology and dynamism dictate the ER–mitochondria contacts in order to regulate the surface expression of certain glycans and thus play a role in GSC recognition and elimination by immune effector cells. Targeting the mitochondrial morphology, dynamism, and contacts with the ER could be an innovative strategy to deplete the cancer stem cell compartment to successfully treat glioblastoma.     

Plant mitochondria actively import DNA via the permeability transition pore complex

Plant mitochondria are remarkable with respect to their content in foreign, alien and plasmid-like DNA, raising the question of the transfer of this information into the organelles. We demonstrate the existence of an active, transmembrane potential-dependent mechanism of DNA uptake into plant mitochondria. The process is restricted to double-strand DNA, but has no obvious sequence specificity. It is most efficient with linear fragments up to a few kilobase pairs. When containing appropriate information, imported sequences are transcribed within the organelles. The uptake likely involves the voltage-dependent anion channel and the adenine nucleotide translocator, i.e. the core components of the mitochondrial permeability transition pore complex in animal cells, but it does not rely on known mitochondrial membrane permeabilization processes. We conclude that DNA import into plant mitochondria might represent a physiological phenomenon with some functional relevance.