Asynchronous origins of ectomycorrhizal clades of Agaricales

The ectomycorrhizal (ECM) symbiosis is the most widespread biotrophic nutritional mode in mushroom-forming fungi. ECM fungi include, though are not limited to, about 5000 described species of Agaricales from numerous, independently evolved lineages. Two central hypotheses suggest different explanations for the origin of ECM fungal diversity: (i) dual origins, initially with the Pinaceae in the Jurassic and later with angiosperms during the Late Cretaceous, and (ii) a simultaneous and convergent radiation of ECM lineages in response to cooling climate during the Palaeogene and advancing temperate ECM plant communities. Neither of these hypotheses is supported here. While we demonstrate support for asynchronous origins of ECM Agaricales, the timing of such events appears to have occurred more recently than suggested by the first hypothesis, first during the Cretaceous and later during the Palaeogene. We are also unable to reject models of rate constancy, which suggests that the diversity of ECM Agaricales is not a consequence of convergent rapid radiations following evolutionary transitions from saprotrophic to ECM habits. ECM lineages of Agaricales differ not only in age, but also in rates of diversification and rate of substitution at nuclear ribosomal RNA loci. These results question the biological uniformity of the ECM guild.     

The Assembly Domain of the Small Capsid Protein of Kaposi's Sarcoma-Associated Herpesvirus

Self-assembly of Kaposi''s sarcoma-associated herpesvirus capsids occurs when six proteins are coexpressed in insect cells using recombinant baculoviruses; however, if the small capsid protein (SCP) is omitted from the coinfection, assembly does not occur. Herein we delineate and identify precisely the assembly domain and the residues of SCP required for assembly. Hence, six residues, R14, D18, V25, R46, G66, and R70 in the assembly domain, when changed to alanine, completely abolish or reduce capsid assembly.     

Coccolithogenesis In Scyphosphaera apsteinii (Prymnesiophyceae)

Coccolithophores are the most significant producers of marine biogenic calcite, although the intracellular calcification process is poorly understood. In the case of Scyphosphaera apsteinii Lohmann 1902, flat ovoid muroliths and bulky, vase‐shaped lopadoliths with a range of intermediate morphologies may be produced by a single cell. This polymorphic species is within the Zygodiscales, a group that remains understudied with respect to ultrastructure and coccolith ontogeny. We therefore undertook an analysis of cell ultrastructure, morphology, and coccolithogenesis. The cell ultrastructure showed many typical haptophyte features, with calcification following a similar pattern to that described for other heterococcolith bearing species including Emiliania huxleyi. Of particular significance was the reticular body role in governing fine‐scale morphology, specifically the central pore formation of the coccolith. Our observations also highlighted the essential role of the inter‐ and intracrystalline organic matrix in growth and arrangement of the coccolith calcite. S. apsteinii secreted mature coccoliths that attached to the plasma membrane via fibrillar material. Time‐lapse light microscopy demonstrated secretion of lopadoliths occurred base first before being actively repositioned at the cell surface. Significantly, growth irradiance influenced the coccosphere composition with fewer lopadoliths being formed relative to muroliths at higher light intensities. Overall, our observations support dynamic metabolic (i.e., in response to growth irradiance), sensory and cytoskeletal control over the morphology and secretion of polymorphic heterococcoliths. With a basic understanding of calcification established, S. apsteinii could be a valuable model to further study coccolithophore calcification and cell physiological responses to ocean acidification.     

Temporal changes in age and sex ratios of forest grouse harvested in northeastern oregon

Ratio of immature (young of the year) grouse to adult birds (I:A) in the harvest of upland game birds is commonly used as an index to annual reproduction; however, I:A ratios can vary as the season progresses producing biased estimates. We analyzed I:A ratios in the daily harvest of dusky grouse (Dendragopus obscurus) and ruffed grouse (Bonasa umbellus) in northeastern Oregon over 28 years (1981–2008) and found that I:A ratios in the harvest declined for both species as the hunting season progressed. We also analyzed ratios of adult female to adult male (AF:AM) grouse to determine if female and male grouse were harvested in equal numbers throughout the harvest season. We found that more males than females of both species were harvested, but that AF:AM ratio of both dusky and ruffed grouse did not change during most of the hunting season. Approximately 50% of the annual harvest occurred during the first 14 days of the hunting season. Therefore, we recommend using the ratios of I:A birds in the first 14 days of the harvest season as the best index to annual reproduction of forest grouse in northeast Oregon. © 2011 The Wildlife Society.     

Reconstitution of the Kaposi's sarcoma-associated herpesvirus nuclear egress complex and formation of nuclear membrane vesicles by coexpression of ORF67 and ORF69 gene products

The Kaposi's sarcoma-associated herpesvirus nuclear egress complex is composed of two proteins, ORF67 and ORF69. In this study, we have recapitulated the KSHV complex by coexpression of these two proteins in insect cells using expression from recombinant baculoviruses. The proteins form a complex at the nuclear membrane as judged by live-cell analysis of protein fusions tagged with green fluorescent protein (GFP) and mCherry. Ultrastructural analysis of infected cells showed that ORF67 expression results in reduplication of the nuclear membrane. When the two proteins are expressed together, numerous virion-size nuclear membrane-derived vesicles were evident at the nuclear margins.     

Biasing the prostaglandin F2α receptor responses toward EGFR-dependent transactivation of MAPK

The G protein-coupled prostaglandin F2α (PGF2α) receptor [F prostanoid (FP) receptor] has been implicated in many physiological events including cardiovascular, respiratory, immune, reproductive, and endocrine responses. Binding of PGF2α to FP receptor elicits inositol production and protein kinase C-dependent MAPK activation through Gα(q) coupling. Here we report that AL-8810, previously characterized as an orthosteric antagonist of PGF2α-dependent, Gα(q)-mediated signaling, potently activates ERK1/2 in a protein kinase C-independent manner. Rather, AL-8810 promoted ERK1/2 activation via an epidermal growth factor receptor transactivation mechanism in both human embryonic kidney 293 cells and in the MG-63 osteoblast-like cells, which express endogenous FP receptors. Neither AL-8810- nor PGF2α-mediated stimulation of FP receptor promoted association with β-arrestins, suggesting that MAPK activation induced by these ligands is independent of β-arrestin's signaling scaffold functions. Interestingly, the spatiotemporal activation of ERK1/2 promoted by AL-8810 and PGF2α showed almost completely opposite responses in the nucleus and the cytosol. Finally, using [(3)H]thymidine incorporation, we noted differential regulation of PGF2α- and AL-8810-induced cell proliferation in MG-63 cells. This study reveals, for the first time, the signaling biased nature of FP receptor orthosteric ligands toward MAPK signaling. Our findings on the specific patterns of ERK1/2 activation promoted by FP receptor ligands may help dissect the distinct roles of MAPK in FP receptor-dependent physiological responses.     

No evidence for an open vessel effect in centrifuge-based vulnerability curves of a long-vesselled liana (Vitis vinifera)

Vulnerability to cavitation curves are used to estimate xylem cavitation resistance and can be constructed using multiple techniques. It was recently suggested that a technique that relies on centrifugal force to generate negative xylem pressures may be susceptible to an open vessel artifact in long-vesselled species. Here, we used custom centrifuge rotors to measure different sample lengths of 1-yr-old stems of grapevine to examine the influence of open vessels on vulnerability curves, thus testing the hypothesized open vessel artifact. These curves were compared with a dehydration-based vulnerability curve. Although samples differed significantly in the number of open vessels, there was no difference in the vulnerability to cavitation measured on 0.14- and 0.271-m-long samples of Vitis vinifera. Dehydration and centrifuge-based curves showed a similar pattern of declining xylem-specific hydraulic conductivity (K(s)) with declining water potential. The percentage loss in hydraulic conductivity (PLC) differed between dehydration and centrifuge curves and it was determined that grapevine is susceptible to errors in estimating maximum K(s) during dehydration because of the development of vessel blockages. Our results from a long-vesselled liana do not support the open vessel artifact hypothesis.     

Computational mapping reveals dramatic effect of Hoogsteen breathing on duplex DNA reactivity with formaldehyde

Formaldehyde has long been recognized as a hazardous environmental agent highly reactive with DNA. Recently, it has been realized that due to the activity of histone demethylation enzymes within the cell nucleus, formaldehyde is produced endogenously, in direct vicinity of genomic DNA. Should it lead to extensive DNA damage? We address this question with the aid of a computational mapping method, analogous to X-ray and nuclear magnetic resonance techniques for observing weakly specific interactions of small organic compounds with a macromolecule in order to establish important functional sites. We concentrate on the leading reaction of formaldehyde with free bases: hydroxymethylation of cytosine amino groups. Our results show that in B-DNA, cytosine amino groups are totally inaccessible for the formaldehyde attack. Then, we explore the effect of recently discovered transient flipping of Watson–Crick (WC) pairs into Hoogsteen (HG) pairs (HG breathing). Our results show that the HG base pair formation dramatically affects the accessibility for formaldehyde of cytosine amino nitrogens within WC base pairs adjacent to HG base pairs. The extensive literature on DNA interaction with formaldehyde is analyzed in light of the new findings. The obtained data emphasize the significance of DNA HG breathing.     

Potential role of prolactin in antipsychotic-mediated association of schizophrenia and type 2 diabetes

It remains unclear why atypical antipsychotics confer a risk for hyperglycemia compared to typical antipsychotics. Atypical antipsychotics antagonize dopamine receptors-2 (D(2)) and serotonin (5-HT) receptors-2, while typical antipsychotics antagonize only D(2) receptors. We aimed at elucidating the mechanistic differences between the role of typical and atypical antipsychotics on prolactin levels and glucose regulation. A Medline search was conducted during 2010 using the search terms type 2 diabetes (T2D), typical/atypical antipsychotics, schizophrenia, prolactin, and serotonin. We discuss the effect of typical and atypical antipsychotics on prolactin levels and glucose regulation. Given that prolactin is under negative control by dopamine and positive control by serotonin, typical antipsychotics induce elevations in prolactin, while atypical antipsychotics do not. Research studies show protective effects of prolactin on T2D. We hypothesize that the difference in induction of T2D between typical and atypical antipsychotics is due to the antipsychotic receptor binding mediated effect in changes in prolactin levels.