Meloidogyne hispanica n. sp. (Nematoda: Meloidogynidae), the 'Seville Root-Knot Nematode'

Meloidogyne hispanica n. sp. is described and illustrated from specimens obtained from peach rootstock, Prunus persica silvestris Batsch, from the Seville district of Spain. The perineal pattern of the female is oval shaped to rectangular with low dorsal arch and often widely spaced lateral lines with fringe-like striae. The stylet, 14.1 μm long, has broad, distinctly set off knobs. Males have a high, rounded head cap that slopes posteriorly. Labial disc and medial lips are fused to form elongate lip structures. The robust styler, 23.5 μm long, has large, rounded knobs that are slightly set off from the shaft. Mean second-stage juveniles length is 392.6 μm. The truncate head region is generally not annulated. The distinctly rounded and raised labial disc and the crescent-shaped medial lips form dumbbell-shaped lip structures. The stylet, 11.1 μm long, has rounded, posteriorly sloping knobs. The slender tail, 46.4 μm long, has large irregular-sized annules in the posterior region and ends in a bluntly rounded tip. Tomato was a good host; tobacco, pepper, and watermelon were poor hosts; cotton and peanut were nonhosts. Meloidogyne hispanica n. sp. reproduces by mitotic parthenogenesis and has a somatic chromosome number of 2n = 33-36. The esterase pattern is unique among Meloidogyne species.     

Beiträge zur Kenntnis der Wasseraufnahme durch oberirdische Pflanzenorgane

Ohne Zusammenfassung     

Contrasting heterozygosity‐fitness correlations across life in a long‐lived seabird

Selection is a central force underlying evolutionary change and can vary in strength and direction, for example across time and space. The fitness consequences of individual genetic diversity have often been investigated by testing for multilocus heterozygosity‐fitness correlations (HFCs), but few studies have been able to assess HFCs across life stages and in both sexes. Here, we test for HFCs using a 26‐year longitudinal individual‐based data set from a large population of a long‐lived seabird (the common tern, Sterna hirundo), where 7,974 chicks and breeders of known age were genotyped at 15 microsatellite loci and sampled for life‐history traits over the complete life cycle. Heterozygosity was not correlated with fledging or post‐fledging prospecting probabilities, but was positively correlated with recruitment probability. For breeders, annual survival was not correlated with heterozygosity, but annual fledgling production was negatively correlated with heterozygosity in males and highest in intermediately heterozygous females. The contrasting HFCs among life stages and sexes indicate differential selective processes and emphasize the importance of assessing fitness consequences of traits over complete life histories.     

Ein Beitrag zur Theorie der organischen symmetrie

Ohne Zusammenfassung Mit 26 Textabbildungen     

Heterodera betulae n. sp. (Heteroderidae), a Cyst-forming Nematode from River Birch

A new species of the genus Heterodera A. Schmidt, 1871 parasitic on river birch, Betula nigra L., is described and illustrated. Females and cysts are lemon-shaped to almost spherical with slight vulval protrusion. Female cuticles have a thick subcrystalline layer. The average cyst size is 763 by 616 [mu]. They are circumfenestrate with small anal opening and lack a yellow phase. The cyst wall pattern is typically network-like. All eggs are retained in the cyst, although a well-developed matrix is formed. The egg shell is without markings. The second-stage larvae average 462 [mu] in length and have 3 incisures in the lateral field. The tail terminal is shorter than the stylet. Males are rare. They have 4 incisures in the lateral field and bifid spicules. The relationship of H. betulae n. sp. to other Heterodera species is obscure.     

Life Cycle,Host Range,and Reproduction of Heterodera betulae

Heterodera betulae, a cyst-forming nematode, originally recovered from roots of river birch in Arkansas, appears to have a limited host range. Of 80 plant species in 20 families tested, only five species of Betula and Cleome spinosa supported reproduction. The minimum time for a complete life cycle was 52 days at 28 C. No reproduction occurred at 31 C or above, and development was very slow below 20 C. Successful population propagations from single larvae demonstrated that males were not necessary for reproduction.     

Crystal Structure and Pathophysiological Role of the Pneumococcal Nucleoside-binding Protein PnrA

Nucleotides are important for RNA and DNA synthesis and, despite a de novo synthesis by bacteria, uptake systems are crucial. Streptococcus pneumoniae, a facultative human pathogen, produces a surface-exposed nucleoside-binding protein, PnrA, as part of an ABC transporter system. Here we demonstrate the binding affinity of PnrA to nucleosides adenosine, guanosine, cytidine, thymidine and uridine by microscale thermophoresis and indicate the consumption of adenosine and guanosine by ¹H NMR spectroscopy. In a series of five crystal structures we revealed the PnrA structure and provide insights into how PnrA can bind purine and pyrimidine ribonucleosides but with preference for purine ribonucleosides. Crystal structures of PnrA:nucleoside complexes unveil a clear pattern of interactions in which both the N- and C- domains of PnrA contribute. The ribose moiety is strongly recognized through a conserved network of H-bond interactions, while plasticity in loop 27–36 is essential to bind purine- or pyrimidine-based nucleosides.Further, we deciphered the role of PnrA in pneumococcal fitness in infection experiments. Phagocytosis experiments did not show a clear difference in phagocytosis between PnrA-deficient and wild-type pneumococci. In the acute pneumonia infection model the deficiency of PnrA attenuated moderately virulence of the mutant, which is indicated by a delay in the development of severe lung infections. Importantly, we confirmed the loss of fitness in co-infections, where the wild-type out-competed the pnrA-mutant. In conclusion, we present the PnrA structure in complex with individual nucleosides and show that the consumption of adenosine and guanosine under infection conditions is required for virulence.