Chemical Camouflage– A Frog's Strategy to Co-Exist with Aggressive Ants

Whereas interspecific associations receive considerable attention in evolutionary, behavioural and ecological literature, the proximate bases for these associations are usually unknown. This in particular applies to associations between vertebrates with invertebrates. The West-African savanna frog Phrynomantis microps lives in the underground nest of ponerine ants (Paltothyreus tarsatus). The ants usually react highly aggressively when disturbed by fiercely stinging, but the frog is not attacked and lives unharmed among the ants. Herein we examined the proximate mechanisms for this unusual association. Experiments with termites and mealworms covered with the skin secretion of the frog revealed that specific chemical compounds seem to prevent the ants from stinging. By HPLC-fractionation of an aqueous solution of the frogs'' skin secretion, two peptides of 1,029 and 1,143 Da were isolated and found to inhibit the aggressive behaviour of the ants. By de novo sequencing using tandem mass spectrometry, the amino acid sequence of both peptides consisting of a chain of 9 and 11 residues, respectively, was elucidated. Both peptides were synthesized and tested, and exhibited the same inhibitory properties as the original frog secretions. These novel peptides most likely act as an appeasement allomone and may serve as models for taming insect aggression.     

The Importance of Using Multiple Approaches for Identifying Emerging Invasive Species: The Case of the Rasberry Crazy Ant in the United States

In the past decade, Houston, Texas has been virtually overrun by an unidentified ant species, the sudden appearance and enormous population sizes and densities of which have received national media attention. The Rasberry Crazy Ant, as it has become known due to its uncertain species status, has since spread to neighboring states and is still a major concern to pest control officials. Previous attempts at identifying this species have resulted in widely different conclusions in regards to its native range, source, and biology. We identify this highly invasive pest species as Nylanderia fulva (Mayr) using morphometric data measured from 14 characters, molecular sequence data consisting of 4,669 aligned nucleotide sites from six independent loci and comparison with type specimens. This identification will allow for the study and control of this emerging pest species to proceed unencumbered by taxonomic uncertainty. We also show that N. fulva has a much wider distribution than previously thought and has most likely invaded all of the Gulf Coast states.     

Ionic balance in the freshwater-adapted Chinese crab, Eriocheir sinensis

Ionic regulation by the gills of the freshwater-adapted Chinese crab, Eriocheir sinensis, was examined. The balance of uptake and loss of NaCl in crabs living in freshwater was established. Urine production was measured directly by cannulating the nephropores. Daily urinary loss of Na+ is equivalent to 16% of the haemolymph Na+ content and is substantially higher than that based on data from indirect measurements reported in the literature. Weight and area of anterior and posterior gills are proportional to body weight. The role of the gills in compensating urinary loss by uptake was determined by analysing changes in Na+ and Cl- concentrations in the external medium in which isolated perfused gills were suspended. In posterior gills, salt loss is quantitatively balanced by NaCl net uptake from an external concentration of 1.3 mmol l(-1) NaCl upwards. The transport constant (Kt) for half maximum saturation of net uptake and saturation of NaCl uptake are 1.5 mmol l(-1) and 4 mmol l(-1), respectively. In contrast to previous studies in which tracer fluxes or transepithelial short-circuit currents were determined, our method of direct ion determination shows that no net uptake of Na+ or Cl- occurs in posterior gills in the absence of the respective counter ion, or when uptake of one ion is blocked by a specific inhibitor. Net uptake of Na+ and Cl- was about equal. We conclude that the uptake of the two ions is coupled. The properties of the branchial ion uptake of E. sinensis correlates with the distribution of this crab in river systems.     

Novel Phylogenetic Algorithm to Monitor Human Tropism in Egyptian H5N1-HPAIV Reveals Evolution toward Efficient Human-to-Human Transmission

Years of endemic infections with highly pathogenic avian influenza (HPAI) A subtype H5N1 virus in poultry and high numbers of infections in humans provide ample opportunity in Egypt for H5N1-HPAIV to develop pandemic potential. In an effort to better understand the viral determinants that facilitate human infections of the Egyptian H5N1-HPAIVvirus, we developed a new phylogenetic algorithm based on a new distance measure derived from the informational spectrum method (ISM). This new approach, which describes functional aspects of the evolution of the hemagglutinin subunit 1 (HA1), revealed a growing group G2 of H5N1-HPAIV in Egypt after 2009 that acquired new informational spectrum (IS) properties suggestive of an increased human tropism and pandemic potential. While in 2006 all viruses in Egypt belonged to the G1 group, by 2011 these viruses were virtually replaced by G2 viruses. All of the G2 viruses displayed four characteristic mutations (D43N, S120(D,N), (S,L)129Δ and I151T), three of which were previously reported to increase binding to the human receptor. Already in 2006–2008 G2 viruses were significantly (p<0.02) more often found in humans than expected from their overall prevalence and this further increased in 2009–2011 (p<0.007). Our approach also identified viruses that acquired additional mutations that we predict to further enhance their human tropism. The extensive evolution of Egyptian H5N1-HPAIV towards a preferential human tropism underlines an urgent need to closely monitor these viruses with respect to molecular determinants of virulence.     

Geometry of proline and hydroxyproline I: An analysis of X-ray crystal structure data

We have carried out an analysis of crystal structure data on prolyl and hydroxyprolyl moieties in small molecules. The flexibility of the pyrrolidine ring due to the pyramidal character of nitrogen has been defined in terms of two projection angles delta 1 and delta 2. The distribution of these parameters in the crystal structures is found to be consistent with results of the energy calculations carried out on prolyl moieties in our laboratory.     

Eine neue mediterrane Reliktart der GattungTaraxacum

Zusammenfassung Aus Griechenland, Peloponnes, wird vom Kyllene-Oros ein neues endemischesTaraxacum, T. cylleneum, beschrieben; es trägt den Namen des Berges, auf dem es 1966 in Gipfelnähe entdeckt wurde.T. cylleneum gehört in die SektionMicrocephala v. S. (ined. ?) (bzw. in die GroßsektionRhodotricha Hand.-Mzt.), die damit erstmalig für Europa nachgewiesen wurde. Es unterscheidet sich vonT. glaciale Huet D. Pav. exHand.-Mzt., mit dem es früher offenbar verwechselt wurde, durch den rötlichen bis roten Pappus sowie den kurzen aber deutlich abgesetzten Schnabel der Achäne und durch die (nahezu) ungehörnten Hüllblätter, durch welche sich die Art auch vonT. primigenium Hand.-Mzt. sicher unterscheidet. VonT. microcephalum Pom., dem wahrscheinlich nächstverwandten Taxon, unterscheidet sie sich wieder durch die Form der Achänen bzw. des Schnabels und durch die Form der Hüllblätter des Blütenstandes. Die bisher untersuchten Pflanzen dieser Art waren allesamt diploid mit 16 Chromosomen. Die Pflanze zeigt nur bei künstlicher Fremdbestäubung einen einigermaßen befriedigenden Fruchtansatz. Die Art scheint streng sexuell zu sein, Kreuzungsexperimente mit anderen diploiden Arten der Gattung schlugen jedoch fehl, was auf die geringe Fertilität der Pflanzen sowie auf die systematisch isolierte Stellung zurückzuführen sein dürfte.

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Summary A new Greek endemicTaraxacum, T. cylleneum, is described, found on Kyllene-Oros, Peloponnesos. It has got the name of the mountain, on which, close by the top, it 1966 had been discovered.Taraxacum, cylleneum n. sp. belongs to the sectionMicrocephala v. S. (ined. ?) (respective in the great-sectionRhodotricha Hand.-Mzt.), whose presence in Europe by that could be proved for the first time. FromT. glaciale Huet D. Pav. exHand.-Mzt., which seems to have been mistaken for,T. cylleneum differs in its reddish to red pappus and the short, but abruptly constricted rostrum of the achenes and the almost incornuted leaflets of the involucrum, by which characteristic it is well distinguished fromT. primigenium Hand.-Mzt. FromT. microcephalum Pomel, which is probable to be the next related taxon,T. cylleneum differs in the shape of the involucrum-leaflets of its inflorescence.All plants of this species, that have been investigated till now, proved diploid with 16 chromosomes (2 n=2 x=16). Fruits are produced only with help of artificial pollination. The species seems to be strongly sexual and allogamous. Crossing experiments with other diploids of the genusTaraxacum were not successful, most probably caused by the low fertility of the plants and the species' systematical isolation.