Economy of mate attraction in the Cassin's finch

Mate attraction can be costly. Thus, individuals should modulate it according to its probable benefits. Specifically, individuals should modulate mate-attraction efforts based on their need for, the probability of attracting, and the reproductive competence of prospective mates. We tested these predictions by monitoring song output in laboratory-housed male Cassin's finches (Carpodacus cassinii) before, during and after brief female exposure following variable periods of isolation from females. We inferred individual reproductive competence from the product of season and reproductive schedule, the latter estimated from moult progress. Males produced little song in the presence of a female but robustly elevated song output in response to female loss. However, mere absence of a female did not elevate song output in males unaccustomed to female proximity. Furthermore, song output in response to female loss increased with her reproductive competence. We suggest that individuals modulate mate-attraction effort based on the benefits such efforts are likely to yield.     

Microbial Transport, Survival, and Succession in a Sequence of Buried Sediments

Abstract Two chronosequences of unsaturated, buried loess sediments, ranging in age from <10,000 years to >1 million years, were investigated to reconstruct patterns of microbial ecological succession that have occurred since sediment burial. The relative importance of microbial transport and survival to succession was inferred from sediment ages, porewater ages, patterns of abundance (measured by direct counts, counts of culturable cells, and total phospholipid fatty acids), activities (measured by radiotracer and enzyme assays), and community composition (measured by phospholipid fatty acid patterns and Biolog substrate usage). Core samples were collected at two sites 40 km apart in the Palouse region of eastern Washington State, near the towns of Washtucna and Winona. The Washtucna site was flooded multiple times during the Pleistocene by glacial outburst floods; the Winona site elevation is above flood stage. Sediments at the Washtucna site were collected from near surface to 14.9 m depth, where the sediment age was approximately 250 ka and the porewater age was 3700 years; sample intervals at the Winona site ranged from near surface to 38 m (sediment age: approximately 1 Ma; porewater age: 1200 years). Microbial abundance and activities declined with depth at both sites; however, even the deepest, oldest sediments showed evidence of viable microorganisms. Same-age sediments had equal quantities of microorganisms, but different community types. Differences in community makeup between the two sites can be attributed to differences in groundwater recharge and paleoflooding. Estimates of the microbial community age can be constrained by porewater and sediment ages. In the shallower sediments (<9 m at Washtucna, <12 m at Winona), the microbial communities are likely similar in age to the groundwater; thus, microbial succession has been influenced by recent transport of microorganisms from the surface. In the deeper sediments, the populations may be considerably older than the porewater ages, since microbial transport is severely restricted in unsaturated sediments. This is particularly true at the Winona site, which was never flooded.     

Inhibition of Epstein-Barr virus infection in vitro and in vivo by soluble CR2 (CD21) containing two short consensus repeats.

The extracellular domain of CR2, the Epstein-Barr virus (EBV)/C3d receptor of B lymphocytes, contains 15 or 16 tandemly arranged short consensus repeat elements (SCR). Recombinant CR2 proteins containing SCR 1 and 2 fused to Staphylococcus aureus protein A (PA-CR2) and to murine complement factor H SCR 20 (CR2FH) were expressed in Escherichia coli and in insect cells, respectively. These recombinant CR2 molecules retained functional activity as indicated by their ability to bind to C3dg in an enzyme-linked immunosorbent assay and to inhibit EBV gp350/220 binding to B cells. PA-CR2 and CR2FH were as efficient in blocking EBV gp350/220 binding as the full-length CR2 extracellular domain, indicating that the first two SCR of CR2 contain the majority of the ligand binding activity of the receptor. PA-CR2 and CR2FH inhibited EBV-induced B-cell proliferation in vitro and blocked the development of EBV-induced lymphoproliferative disease in severe combined immunodeficient mice reconstituted with human lymphocytes. These studies indicate that soluble forms of truncated CR2 proteins may have potential therapeutic value in the treatment of EBV-induced lymphoproliferative disorders in humans that involve viral replication.     

Ultrastructure of the Host-Pathogen Relationship in Entomosporium Leaf Spot Disease of Photinia

Entomosporium mespili appears to be a hemibiotroph on infected Photinia leaves. This fungal pathogen produced distinctive haustoria in living host cells in young lesions. Each haustorium possessed a long slender neck with a single septum and an enlarged distal body that contained a single nucleus. A collar of host cell wall material was associated with the haustorial neck. Intact haustoria also were found in necrotic cells of older lesions. However, by this stage of disease development, the pathogen also possessed an extensive system of branched, septate hyphae that grew indiscriminately between and through dead and dying host cells. These hyphae eventually gave rise to a subcutaneous layer of sporogenous cells that formed conidia.     

Bioluminescence imaging reveals inhibition of tumor cell proliferation by Alzheimer's amyloid β protein

Background  

Cancer and Alzheimer's disease (AD) are two seemingly distinct diseases and rarely occur simultaneously in patients. To explore molecular determinants differentiating pathogenic routes towards AD or cancer, we investigate the role of amyloid β protein (Aβ) on multiple tumor cell lines that are stably expressing luciferase (human glioblastoma U87; human breast adenocarcinoma MDA-MB231; and mouse melanoma B16F).