Ground vegetation in the Mongolian taiga forest‐steppe ecotone does not offer evidence for the human origin of grasslands

Question: Is the vegetation of meadow and mountain steppes distinct from the ground vegetation of light taiga forests in the transitional zone between these biomes? Location: Western Khentey Mountains, northern Mongolia. Methods: Vegetation was recorded from 100‐m² plots from all dominant types of light taiga forest and dry grassland. Distinctness of ground vegetation was studied with Detrended Correspondence Analysis (DCA). Results: Ground vegetation in the light taiga was significantly different from the herbal vegetation of meadow and mountain steppes. Clear separation was only absent for the Car ex amgunensis meadow steppes that occur in a narrow strip along the forest edge and are partly shaded by trees. Forest and steppe communities followed a moisture gradient according to the DCA ordination with light taiga forests at the moistest sites and steppe communities at the driest sites. Ulmus pumila open woodlands diverged from this pattern, because of their close spatial and phytosociological relationship to mountain steppes. Conclusions: The present results do not support the assumption that grasslands in Mongolia's transitional zone between forest and steppe would generally resemble the ground vegetation of light taiga forests. This contradicts a published hypothesis stating that the vegetation of meadow and mountain steppes would not clearly differ from ground vegetation of light taiga forests in the forest‐steppe transitional zone of Mongolia.     

Cellular adhesion molecules as targets for bacterial infection

A large number of bacterial pathogens targets cell adhesion molecules to establish an intimate contact with host cells and tissues. Members of the integrin, cadherin and immunoglobulin-related cell adhesion molecule (IgCAM) families are frequently recognized by specific bacterial surface proteins. Binding can trigger bacterial internalization following cytoskeletal rearrangements that are initiated upon receptor clustering. Moreover, signals emanating from the occupied receptors can result in cellular responses such as gene expression events that influence the phenotype of the infected cell. This review will address recent advances in our understanding of bacterial engagement of cellular adhesion molecules by discussing the binding of integrins by Staphylococcus aureus as well as the exploitation of IgCAMs by pathogenic Neisseria species.     

Microbial production of single-cell protein from deproteinized whey concentrates

Deproteinized sweet and sour cheese whey concentrates were investigated for their suitability as substrates for the production of single-cell protein with Kluyveromyces marxianus CBS 6556 up to a 100-l scale. An important factor for gaining high cell concentrations was the use of the Crabtree-negative strain K. marxianus CBS 6556. Supplements such as trace elements, ammonium and calcium were required for the complete conversion of sweet whey concentrates into biomass, whereas sour whey concentrates had to be supplemented with ammonium, trace elements and vitamins. After improvement, biomass dry concentrations of up to 50 g l⁻¹ could be reached with Yx/s values of 0.52 for sweet whey and of up to 65 g l⁻¹ with Yx/s values of 0.48 for sour whey concentrates. The chemical oxygen demand of the whey concentrates were reduced by 80%. The cells were used for the analysis of amino acid and ash composition, showing a distinct increase of eight out of ten essential amino acids compared to sweet and sour whey protein and exceeding the World Health Organisation guidelines for valine, leucine, isoleucine, threonine, phenylalanine and tyrosine.     

The significance of precipitation and substrate chemistry for epiphytic lichen diversity in spruce-fir forests of the Salish Mountains, northwestern Montana

The relevance of chemical site factors for the abundance of epiphytic lichens was studied in Picea engelmannii-Abies lasiocarpa forests of the Salish Mountains, northwestern Montana, USA. The Salish Mountains are an area with relatively low atmospheric pollutant load and low precipitation. Canonical correspondence analysis (CCA) suggests that cover of several lichen species was limited by high Mn concentrations of bark or by high ratios of Mn to Ca, Mg and Fe. Mn in the bark is known primarily to derive from the soil. An effect of Mn concentration or Mn/Ca and Mn/Mg ratios was not found on A. lasiocarpa. This suggests that A. lasiocarpa deposits Mn in the bark in a physiologically inactive form as already known from A. balsamea. Precipitation chemistry was apparently less relevant for epiphytic lichen distribution in the Salish Mountains, as no correlations between element concentrations in stemflow and cover values were found and as amounts of stemflow were small. However, precipitation in the study year was less than average. The lacking significance of precipitation chemistry is probably the cause why epiphytic lichen vegetation differed less between living and dead trees in the Salish Mountains than in highly polluted coniferous forests studied by our group in Germany; in Germany, the difference between living and dead trees was attributed to reduced interception of pollutants from the atmosphere by trees with reduced crown surface. The result of the present study that small-scale variation of epiphytic lichen abundance is only partly explainable by chemical parameters gives rise to the assumption that microclimate (e.g., moisture), which has not been systematically explored, could be an important site factor for epiphytic lichens in the Salish Mountains. Furthermore, tree age was identified by CCA as a relevant site factor for lichens on P. engelmannii.     

Identification of paracrine neuroprotective candidate proteins by a functional assay-driven proteomics approach

Glial cells support neuronal survival and function by secreting neurotrophic cytokines. Retinal Mueller glial cells (RMGs) support retinal neurons, especially photoreceptors. These highly light-sensitive sensory neurons receive vision, and their death results in blinding diseases. It has been proposed that RMGs release factors that support photoreceptor survival, but the nature of these factors remains to be elucidated. To discover such neurotrophic factors, we developed an integrated work flow toward systematic identification of neuroprotective proteins, which are, like most cytokines, expressed only in minute amounts. This strategy can be generally applied to identify secreted bioactive molecules from any body fluid once a recipient cell for this activity is known. Toward this goal we first isolated conditioned medium (CM) from primary porcine RMGs cultured in vitro and tested for survival-promoting activity using primary photoreceptors. We then developed a large scale, microplate-based cellular high content assay that allows rapid assessment of primary photoreceptor survival concomitant with biological activity in vitro. The enrichment strategy of bioactive proteins toward their identification consists of several fractionation steps combined with tests for biological function. Here we combined 1) size fractionation, 2) ion exchange chromatography, 3) reverse phase liquid chromatography, and 4) mass spectrometry (Q-TOF MS/MS or MALDI MS/MS) for protein identification. As a result of this integrated work flow, the insulin-like growth factor-binding proteins IGFBP5 and IGFBP7 and connective tissue growth factor (CTGF) were identified as likely candidates. Cloning and stable expression of these three candidate factors in HEK293 cells produced conditioned medium enriched for either one of the factors. IGFBP5 and CTGF, but not IGFBP7, significantly increased photoreceptor survival when secreted from HEK293 cells and when added to the original RMG-CM. This indicates that the survival-promoting activity in RMG-CM is multifactorial with IGFBP5 and CTGF as an integral part of this activity.     

Ductus ejaculatorius peptide 99B (DUP99B), a novel Drosophila melanogaster sex-peptide pheromone.

We have characterized a glycosylated, 31 amino-acid peptide of 4932 Da isolated from Drosophila melanogaster males. The mature peptide contains a sugar moiety of 1184 Da at a NDT consensus glycosylation site and a disulfide bond. It is synthesized in the male ejaculatory duct via a 54 amino-acid precursor containing an N-terminal signal peptide and Arg-Lys at the C-terminus which is cleaved off during maturation. The gene contains an intron of 53 bp and is localized in the cytological region 99B of the D. melanogaster genome. The peptide is therefore named DUP99B (for ductus ejaculatorius peptide, cytological localization 99B). The C-terminal parts of mature DUP99B and D. melanogaster sex-peptide (ACP70A) are highly homologous. Injected into virgin females, DUP99B elicits the same postmating responses as sex-peptide (increased oviposition, reduced receptivity). These effects are also induced by de-glycosylated native peptide or synthetic DUP99B lacking the sugar moiety. Presence of the glycosyl group, however, decreases the amount needed to elicit the postmating responses. Homologies in the coding regions of the two exons of DUP99B and sex-peptide, respectively, suggest that the two genes have evolved by gene duplication. Thus, we consider these two genes to be members of the new sex-peptide gene family.     

Protective Oral Vaccination against Infectious bursal disease virus Using the Major Viral Antigenic Protein VP2 Produced in Pichia pastoris

Infectious bursal disease virus (IBDV) causes economically important immunosuppressive disease in young chickens. The self-assembling capsid protein (VP2) from IBDV strain IR01 was expressed in Pichia pastoris resulting in the formation of homomeric, 23-nm infectious bursal disease subviral particles (IBD-SVPs) with a yield of 76 mg/l before and 38 mg/l after purification. Anti-IBDV antibodies were detected in chickens injected with purified IBD-SVPs or fed with either purified IBD-SVPs or inactivated P. pastoris cells containing IBD-VP2 (cell-encapsulated). Challenge studies using the heterologous classical IBDV strain (MB3) showed that intramuscular vaccination with 20 µg purified IBD-SVPs conferred full protection, achieved complete virus clearance and prevented bursal damage and atrophy, compared with only 40% protection, 0–10% virus clearance accompanied by severe atrophy and substantial bursal damage in mock-vaccinated and challenge controls. The commercial IBDV vaccine also conferred full protection and achieved complete virus clearance, albeit with partial bursal atrophy. Oral administration of 500 µg purified IBD-SVPs with and without adjuvant conferred 100% protection but achieved only 60% virus clearance with adjuvant and none without it. Moderate bursal damage was observed in both cases but the inclusion of adjuvant resulted in bursal atrophy similar to that observed with live-attenuated vaccine and parenteral administration of 20 µg purified IBD-SVPs. The oral administration of 250 mg P. pastoris cells containing IBD-VP2 resulted in 100% protection with adjuvant and 60% without, accompanied by moderate bursal damage and atrophy in both groups, whereas 25 mg P. pastoris cells containing IBD-VP2 resulted in 90–100% protection with moderate bursal lesions and severe atrophy. Finally, the oral delivery of 50 µg purified IBD-SVPs achieved 40–60% protection with severe bursal lesions and atrophy. Both oral and parenteral administration of yeast-derived IBD-VP2 can therefore induce a specific and protective immune response against IBDV without affecting the growth rate of chickens.