Characterization of Picea abies (L.) Karst. ectomycorrhizas: discrepancy between classification according to macroscopic versus microscopic features

Summary In a 3-year study of ectomycorrhizal diversity in 2 Norway spruce stands in Switzerland the macroscopically classified ectomycorrhizal types were analyzed microscopically to compare the results of the 2 approaches. A total of 22 ectomycorrhizal types were macroscopically classified in the 2 stands. Microscopic investigations — particularly of mantle structures — resulted in the identification of 7 additional types to give a total of 29. These additional types resulted from separation of macroscopically identical types occurring on both stands (type-pairs) at the microscopic level. The problematic nature of characterization and classification of ectomycorrhizas is discussed.     

Fiber production in vitro from a conditional fiberless mutant of cotton

A single-gene temperature-sensitive mutation regulates fiber development from ovular epidermal cells of a cotton strain derived from Gossypium arboreum L. Fiber development is permitted when unfertilized ovules are cultured at 30°C (and below) in nutrient medium containing indoleacetic acid and gibberellic acid, but it is restricted in identical medium at 32°C (and above).     

The process utility of thermotolerant methylotrophic bacteria: I. An evaluation in chemostat culture

In Part l, the process utility of a thermotolerant methylotrophic bacterium is evaluated in chemostat culture under conditions where methanol, methanol/formaldehyde mixtures and dual methanol/ammonia limitation occurred. The results show that the bacterium studied was nonfastideous under steady-state operation, in contrast to results obtained in batch culture. For application in industrial wastewater treatment processes the bacterium should be employed in systems where the biomass residence time exceeds 5 h, i. e., dilution rates < O.2 h(-1). Under such conditions, methanol was essentially exhausted and the biomass yield coefficient was lowered.     

Regulation of the synthesis of methanol oxidizing enzymes inKloeckera sp. 2201 andHansenula polymorpha,a comparison

A comparative study was made of the regulation of the synthesis of methanol dissimilating enzymes inkloeckera sp. 2201 andHansenula polymorpha using chemostat and batch growth conditions and methanol or glucose as carbon sources. During growth in methanol-limited chemostat cultures similar enzyme patterns for alcohol oxidase, catalase, formaldehyde dehydrogenase and formate dehydrogenase in the two yeasts were found. When growing in batch culture with glucoseH. polymorpha, but notKloeckera sp. 2201, was found to produce ethanol which might affect the synthesis of these enzymes.     

Model-based inference of neutralizing antibody avidities against influenza virus

To assess the response to vaccination, quantity (concentration) and quality (avidity) of neutralizing antibodies are the most important parameters. Specifically, an increase in avidity indicates germinal center formation, which is required for establishing long-term protection. For influenza, the classical hemagglutination inhibition (HI) assay, however, quantifies a combination of both, and to separately determine avidity requires high experimental effort. We developed from first principles a biophysical model of hemagglutination inhibition to infer IgG antibody avidities from measured HI titers and IgG concentrations. The model accurately describes the relationship between neutralizing antibody concentration/avidity and HI titer, and explains quantitative aspects of the HI assay, such as robustness to pipetting errors and detection limit. We applied our model to infer avidities against the pandemic 2009 H1N1 influenza virus in vaccinated patients (n = 45) after hematopoietic stem cell transplantation (HSCT) and validated our results with independent avidity measurements using an enzyme-linked immunosorbent assay with urea elution. Avidities inferred by the model correlated with experimentally determined avidities (ρ = 0.54, 95% CI = [0.31, 0.70], P < 10⁻⁴). The model predicted that increases in IgG concentration mainly contribute to the observed HI titer increases in HSCT patients and that immunosuppressive treatment is associated with lower baseline avidities. Since our approach requires only easy-to-establish measurements as input, we anticipate that it will help to disentangle causes for poor vaccination outcomes also in larger patient populations. This study demonstrates that biophysical modelling can provide quantitative insights into agglutination assays and complement experimental measurements to refine antibody response analyses.     

Plasmodium berghei sporozoites in nonreplicative vacuole are eliminated by a PI3P‐mediated autophagy‐independent pathway

The protozoan parasite Plasmodium, causative agent of malaria, invades hepatocytes by invaginating the host cell plasma membrane and forming a parasitophorous vacuole membrane (PVM). Surrounded by this PVM, the parasite undergoes extensive replication. Parasites inside a PVM provoke the Plasmodium‐associated autophagy‐related (PAAR) response. This is characterised by a long‐lasting association of the autophagy marker protein LC3 with the PVM, which is not preceded by phosphatidylinositol 3‐phosphate (PI3P)‐labelling. Prior to productive invasion, sporozoites transmigrate several cells and here we describe that a proportion of traversing sporozoites become trapped in a transient traversal vacuole, provoking a host cell response that clearly differs from the PAAR response. These trapped sporozoites provoke PI3P‐labelling of the surrounding vacuolar membrane immediately after cell entry, followed by transient LC3‐labelling and elimination of the parasite by lysosomal acidification. Our data suggest that this PI3P response is not only restricted to sporozoites trapped during transmigration but also affects invaded parasites residing in a compromised vacuole. Thus, host cells can employ a pathway distinct from the previously described PAAR response to efficiently recognise and eliminate Plasmodium parasites.