Responses in pigmentation and anti-oxidant expression in Arctic Daphnia along gradients of DOC and UV exposure

Responses in carapace melanization and expression of the majoranti-oxidant catalase (CAT) and glutathione transferase (GST)in Arctic Daphnia were assessed in enclosures along a gradientof dissolved organic carbon (DOC). This gradient was createdby adding freeze-dried humic matter to 2 m³ UV-transparent enclosures,yielding final nominal concentrations of 1, 2.5, 5 and 10 mgC l^-1. The UV attenuation was strongly affected by additionsof DOC, and attenuation coefficients at 320 nm increased from3.0 in the control to approximately 3.5 and 11.0 m^-1 in the1 and 10 mg DOC treatments respectively. Most Daphnia showedpronounced carapace melanization, and the absorbance of short-waveradiation through the carapace was strongly related to the degreeof melanization. Nevertheless, the different UV climate in theenclosures did not cause any short-term adaptation in Daphniapigmentation over a 3 week period. The levels of CAT and GSTwere assessed over time in the control and at 10 mg DOC. Theseenzymes displayed opposite patterns, with somewhat lower activitiesof CAT at low DOC (control) relative to 10 mg DOC, while theopposite was found for GST. There was also a significant negativecorrelation between CAT and solar irradiation for GST in bothbags, while no effects were found for GST.     

Temporal variability of top-down forces and their role in host choice evolution of phytophagous arthropods

The role of top-down forces in host choice evolution of phytophagous arthropods is the subject of a vividly animated debate. Empirical evidence for the evolutionary role of top-down forces comes from studies showing that phytophagous arthropods prefer hosts that entail enemy-free space. The aim of this paper is to draw the attention of plant–arthropod researchers to the potentially, temporally variable nature of third trophic level effects. We show that this aspect is largely neglected in studies on enemy-free space, despite the fact that relative enemy impact varies seasonally among plants in at least some studies. We conclude that rigorous testing of the enemy-free space hypothesis can only be performed when within and between season variation in higher trophic level effects is taken into account.     

Results of combined radiotherapy and hormonal treatment of prostate cancer patients with initial PSA value >40 ng/ml

AimTo evaluate the outcome of prostate cancer patients with initial PSA value >40 ng/ml.BackgroundThe outcome of prostate cancer patients with very high initial PSA value is not known and patients are frequently treated with palliative intent. We analyzed the outcome of radical combined hormonal treatment and radiotherapy in prostate cancer patients with initial PSA value >40 ng/ml.MethodsBetween January 2003 and December 2007 we treated, with curative intent, 56 patients with non-metastatic prostate cancer and initial PSA value >40 ng/ml. The treatment consisted of two months of neoadjuvant hormonal treatment (LHRH analog), radical radiotherapy (68–78 Gy, conformal technique) and an optional two-year adjuvant hormonal treatment.ResultsThe median time of follow up was 61 months. 5-Year overall survival was 90%. 5-Year biochemical disease free survival was 62%. T stage, Gleason score, PSA value, and radiotherapy dose did not significantly influence the outcome. Late genitourinal and gastrointestinal toxicity was acceptable.ConclusionRadical treatment in combination with hormonal treatment and radiotherapy can be recommended for this subgroup of prostate cancer patients with good performance status and life expectancy.     

Elevated glutamate and NMDA disrupt production of the second messenger cyclic GMP in the early postnatal mouse cortex

The second messenger cyclic guanosine monophosphate (cGMP) plays many roles during nervous system development. Consequently, cGMP production shows complex patterns of regulation throughout early development. Elevated glutamate levels are known to increase cGMP levels in the mature nervous system. A number of clinical conditions including ischemia and perinatal asphyxia can result in elevated glutamate levels in the developing brain. To investigate the effects of elevated glutamate levels on cGMP in the developing cortex we exposed mouse brain slices to glutamate or N‐methyl D ‐aspartate (NMDA). We find that at early postnatal stages when the endogenous production of cGMP is high, glutamate or NMDA exposure results in a significant lowering of the overall production of cGMP in the cortex, unlike the situation in the mature brain. However, this response pattern is complex with regional and cell‐type specific exceptions to the overall lowered cGMP production. These data emphasize that the response of the developing brain to physiological disturbances can be different from that of the mature brain, and must be considered in the context of the developmental events occurring at the time of disturbance. © 2009 Wiley Periodicals, Inc. Develop Neurobiol, 2009     

Tyrant flycatchers coming out in the open: phylogeny and ecological radiation of Tyrannidae (Aves, Passeriformes)

Tyrant flycatchers constitute a substantial component of the land bird fauna in all South American habitats. Past interpretations of the morphological and ecological evolution in the group have been hampered by the lack of a well‐resolved hypothesis of their phylogenetic interrelationships. Here, we present a well‐resolved phylogeny based on DNA sequences from three nuclear introns for 128 taxa. Our results confirm much of the overall picture of Tyrannidae relationships, and also identify several novel relationships. The genera Onychorhynchus, Myiobius and Terenotriccus are placed outside Tyrannidae and may be more closely related to Tityridae. Tyrannidae consists of two main lineages. An expanded pipromorphine clade includes flatbills, tody‐tyrants and antpipits, and also Phylloscartes and Pogonotriccus. The spadebills, Neopipo and Tachuris are their closest relatives. The remainder of the tyrant flycatchers forms a well‐supported clade, subdivided in two large subclades, which differ consistently in foraging behaviour, the perch‐gleaning elaeniines and the sallying myiarchines, tyrannines and fluvicolines. A third clade is formed by the genera Myiotriccus, Pyrrhomyias, Hirundinea and three species currently placed in Myiophobus. Ancestral habitat reconstruction and divergence date estimation suggest that early divergence events in Tyrannida took place in a humid forest environment during the Oligocene. Large‐scale diversification in open habitats is confined to the clade consisting of the elaeniines, myiarchines, tyrannines and fluvicolines. This radiation correlates in time to the expansion of semi‐open and open habitats from the mid‐Miocene (c. 15 Mya) onwards. The pipromorphine, elaeniine and myiarchine–tyrannine–fluvicoline clades each employ distinct foraging strategies (upward striking, perch‐gleaning and sallying, respectively), but the degree of diversity in morphology and microhabitat exploitation is markedly different between these clades. While the pipromorphines and elaeniines each are remarkably homogenous in morphology and exploit a restricted range of microhabitats, the myiarchine–tyrannine–fluvicoline clade is more diverse in these respects. This greater ecological diversity, especially as manifested in their success in colonizing a wider spectrum of open habitats, appears to be connected to a greater adaptive flexibility of the search‐and‐sally foraging behaviour.     

The Design and Characterization of Receptor-selective APRIL Variants

A proliferation-inducing ligand (APRIL), a member of the TNF ligand superfamily with an important role in humoral immunity, is also implicated in several cancers as a prosurvival factor. APRIL binds two different TNF receptors, B cell maturation antigen (BCMA) and transmembrane activator and cylclophilin ligand interactor (TACI), and also interacts independently with heparan sulfate proteoglycans. Because APRIL shares binding of the TNF receptors with B cell activation factor, separating the precise signaling pathways activated by either ligand in a given context has proven quite difficult. In this study, we have used the protein design algorithm FoldX to successfully generate a BCMA-specific variant of APRIL, APRIL-R206E, and two TACI-selective variants, D132F and D132Y. These APRIL variants show selective activity toward their receptors in several in vitro assays. Moreover, we have used these ligands to show that BCMA and TACI have a distinct role in APRIL-induced B cell stimulation. We conclude that these ligands are useful tools for studying APRIL biology in the context of individual receptor activation.     

A chromosomal paracentric inversion associated with T-DNA integration in Arabidopsis

T-DNA integration in the nuclear plant genome may lead to rearrangements of the plant target site. Here we present evidence for a chromosomal inversion of 26 cM bordered by two T-DNAs in direct orientation, which is linked to the mgoun2 mutation. The integration sites of the T-DNAs map at positions 80 and 106 of chromosome I and we show that each T-DNA is bordered by plant sequences from positions 80 and 106, respectively. Although the T-DNAs are physically distant, they are genetically closely linked. In addition, three markers located on the chromosome segment between the two T-DNA integration sites show no recombination with the mgo2 mutation. We show that the inversion cannot be a consequence of a recombination event between the two T-DNAs, but that the integration of the T-DNAs and the inversion were two temporally linked events. T-DNA integration mechanisms that could have led to this inversion are discussed.