Establishment of compatibility in the Ustilago maydis/maize pathosystem

The fungus Ustilago maydis is a biotrophic pathogen parasitizing on maize. The most prominent symptoms of the disease are large tumors in which fungal proliferation and spore differentiation occur. In this study, we have analyzed early and late tumor stages by confocal microscopy. We show that fungal differentiation occurs both within plant cells as well as in cavities where huge aggregates of fungal mycelium develop. U. maydis is poorly equipped with plant CWDEs and we demonstrate by array analysis that the respective genes follow distinct expression profiles at early and late stages of tumor development. For the set of three genes coding for pectinolytic enzymes, deletion mutants were generated by gene replacement. Neither single nor triple mutants were affected in pathogenic development. Based on our studies, we consider it unlikely that U. maydis feeds on carbohydrates derived from the digestion of plant cell wall material, but uses its set of plant CWDEs for softening the cell wall structure as a prerequisite for in planta growth.     

Quantifying the effects of switchgrass (Panicum virgatum) on deep organic C stocks using natural abundance 14C in three marginal soils

Perennial bioenergy crops have been shown to increase soil organic carbon (SOC) stocks, potentially offsetting anthropogenic C emissions. The effects of perennial bioenergy crops on SOC are typically assessed at shallow depths (<30 cm), but the deep root systems of these crops may also have substantial effects on SOC stocks at greater depths. We hypothesized that deep (>30 cm) SOC stocks would be greater under bioenergy crops relative to stocks under shallow‐rooted conventional crop cover. To test this, we sampled soils to between 1‐ and 3‐m depth at three sites in Oklahoma with 10‐ to 20‐year‐old switchgrass (Panicum virgatum) stands, and collected paired samples from nearby fields cultivated with shallow rooted annual crops. We measured root biomass, total organic C, ¹⁴C, ¹³C, and other soil properties in three replicate soil cores in each field and used a mixing model to estimate the proportion of recently fixed C under switchgrass based on ¹⁴C. The subsoil C stock under switchgrass (defined over 500–1500 kg/m² equivalent soil mass, approximately 30–100 cm depth) exceeded the subsoil stock in neighboring fields by 1.5 kg C/m² at a sandy loam site, 0.6 kg C/m² at a site with loam soils, and showed no significant difference at a third site with clay soils. Using the mixing model, we estimated that additional SOC introduced after switchgrass cultivation comprised 31% of the subsoil C stock at the sandy loam site, 22% at the loam site, and 0% at the clay site. These results suggest that switchgrass can contribute significantly to subsoil organic C—but also indicated that this effect varies across sites. Our analysis shows that agricultural strategies that emphasize deep‐rooted grass cultivars can increase soil C relative to conventional crops while expanding energy biomass production on marginal lands.     

Drought signal transduction in plants

Water deficit is one of the most common environmental limitations of crop productivity by affecting growth through alterations in metabolism and gene expression. The mechanisms involved in drought perception and signal transduction pathways are poorly understood. The participation of the plant hormone abscisic acid (ABA) has been well established. ABA levels increase when there are changes in the environment that result in cellular dehydration. Different approaches have been taken to understanding the molecular responses to desiccation and how ABA regulates gene expression. Recent efforts have identified particular topics of importance in the dissection of the signal transduction pathway which are summarized as follows: physiological approaches: identification of signalling molecules. Genetic approaches: the use of mutants, and Molecular approaches: promoter analysis.     

Social development of stumptail macaques (Macaca arctoides): Synchrony of changes in mother-infant interactions and individual behaviors during the first 60 days of life

Several categories of social and individual behaviors were recorded during the first 60 days of life for seven stumptail macaques. Mother-infant interactions tended to decelerate in synchrony with increases in infant nonsocial behaviors, such as object manipulation. Several aspects of stumptail social growth during the first two months were similar to those of rhesus and other macaques. Approaching-leaving, which has been used previously as an index of waning of the mother-infant bond, was due more to infants than to mothers during the second month of life     

A Chlorate-Formaldehyde Modification of the Golgi Method

Pieces of fresh nervous tissue 3-5 mm thick are put into a mixture of: 6% K₂Cr₂O₇, 40 ml; 5% KClO₃, 20 ml; 20% chloral hydrate, 30 ml; and concentrated formalin (38% HCHO), 10 ml; allowed to fix 3 days, with a daily change of fluid; transferred to 3% K₂Cr₂O₇ for 3 days, with twice daily changes; then to 1% AgNO₃ for 3 days at 20-25° C. Frozen sections are cut, dehydrated, cleared and mounted in Permount with a cover glass. The method gives good results for microglia and oligodendroglia in addition to the usual staining of nerve cells and their processes.     

A Monoclonal Antibody that Specifically Recognizes m'A Nucleoside

Abstract

A hybridoma against the nucleoside m⁶A has been obtained from mouse spleen. This hybridoma was named H65 and it secretes monoclonal antibodies anti-m⁶A. The competition assays showed that the monoclonal antibody was highly specific for m⁶A nucleoside.     

Note: A Convenient Method for the Preparation of N2, N2-Dimethylguanosine

Abstract

The preparation of N², N²-dimethylguanosine is described. The use of the 2-(p-nitrophenyl)ethyl group instead of the benzyl protecting group for the O⁶ position of the guanine ring resulted in better yields and shorter protocols.