Priming of inducible defenses protects Norway spruce against tree-killing bark beetles

Plants can form an immunological memory known as defense priming, whereby exposure to a priming stimulus enables quicker or stronger response to subsequent attack by pests and pathogens. Such priming of inducible defenses provides increased protection and reduces allocation costs of defense. Defense priming has been widely studied for short-lived model plants such as Arabidopsis, but little is known about this phenomenon in long-lived plants like spruce. We compared the effects of pretreatment with sublethal fungal inoculations or application of the phytohormone methyl jasmonate (MeJA) on the resistance of 48-year-old Norway spruce (Picea abies) trees to mass attack by a tree-killing bark beetle beginning 35 days later. Bark beetles heavily infested and killed untreated trees but largely avoided fungus-inoculated trees and MeJA-treated trees. Quantification of defensive terpenes at the time of bark beetle attack showed fungal inoculation induced 91-fold higher terpene concentrations compared with untreated trees, whereas application of MeJA did not significantly increase terpenes. These results indicate that resistance in fungus-inoculated trees is a result of direct induction of defenses, whereas resistance in MeJA-treated trees is due to defense priming. This work extends our knowledge of defense priming from model plants to an ecologically important tree species.     

Cotranslational folding of alkaline phosphatase in the periplasm of Escherichia coli

Cotranslational protein folding studies using Force Profile Analysis, a method where the SecM translational arrest peptide is used to detect folding‐induced forces acting on the nascent polypeptide, have so far been limited mainly to small domains of cytosolic proteins that fold in close proximity to the translating ribosome. In this study, we investigate the cotranslational folding of the periplasmic, disulfide bond‐containing Escherichia coli protein alkaline phosphatase (PhoA) in a wild‐type strain background and a strain background devoid of the periplasmic thiol: disulfide interchange protein DsbA. We find that folding‐induced forces can be transmitted via the nascent chain from the periplasm to the polypeptide transferase center in the ribosome, a distance of ~160 Å, and that PhoA appears to fold cotranslationally via at least two disulfide‐stabilized folding intermediates. Thus, Force Profile Analysis can be used to study cotranslational folding of proteins in an extra‐cytosolic compartment, like the periplasm.     

Factor H Binds to the Hypervariable Region of Many Streptococcus pyogenes M Proteins but Does Not Promote Phagocytosis Resistance or Acute Virulence

Many pathogens express a surface protein that binds the human complement regulator factor H (FH), as first described for Streptococcus pyogenes and the antiphagocytic M6 protein. It is commonly assumed that FH recruited to an M protein enhances virulence by protecting the bacteria against complement deposition and phagocytosis, but the role of FH-binding in S. pyogenes pathogenesis has remained unclear and controversial. Here, we studied seven purified M proteins for ability to bind FH and found that FH binds to the M5, M6 and M18 proteins but not the M1, M3, M4 and M22 proteins. Extensive immunochemical analysis indicated that FH binds solely to the hypervariable region (HVR) of an M protein, suggesting that selection has favored the ability of certain HVRs to bind FH. These FH-binding HVRs could be studied as isolated polypeptides that retain ability to bind FH, implying that an FH-binding HVR represents a distinct ligand-binding domain. The isolated HVRs specifically interacted with FH among all human serum proteins, interacted with the same region in FH and showed species specificity, but exhibited little or no antigenic cross-reactivity. Although these findings suggested that FH recruited to an M protein promotes virulence, studies in transgenic mice did not demonstrate a role for bound FH during acute infection. Moreover, phagocytosis tests indicated that ability to bind FH is neither sufficient nor necessary for S. pyogenes to resist killing in whole human blood. While these data shed new light on the HVR of M proteins, they suggest that FH-binding may affect S. pyogenes virulence by mechanisms not assessed in currently used model systems.     

Hyaluronan and N-ERC/Mesothelin as Key Biomarkers in a Specific Two-Step Model to Predict Pleural Malignant Mesothelioma

Purpose

Diagnosis of malignant mesothelioma is challenging. The first available diagnostic material is often an effusion and biochemical analysis of soluble markers may provide additional diagnostic information. This study aimed to establish a predictive model using biomarkers from pleural effusions, to allow early and accurate diagnosis.

Patients and Methods

Effusions were collected prospectively from 190 consecutive patients at a regional referral centre. Hyaluronan, N-ERC/mesothelin, C-ERC/mesothelin, osteopontin, syndecan-1, syndecan-2, and thioredoxin were measured using ELISA and HPLC. A predictive model was generated and validated using a second prospective set of 375 effusions collected consecutively at a different referral centre.

Results

Biochemical markers significantly associated with mesothelioma were hyaluronan (odds ratio, 95% CI: 8.82, 4.82–20.39), N-ERC/mesothelin (4.81, 3.19–7.93), CERC/mesothelin (3.58, 2.43–5.59) and syndecan-1 (1.34, 1.03–1.77). A two-step model using hyaluronan and N-ERC/mesothelin, and combining a threshold decision rule with logistic regression, yielded good discrimination with an area under the ROC curve of 0.99 (95% CI: 0.97–1.00) in the model generation dataset and 0.83 (0.74–0.91) in the validation dataset, respectively.

Conclusions

A two-step model using hyaluronan and N-ERC/mesothelin predicts mesothelioma with high specificity. This method can be performed on the first available effusion and could be a useful adjunct to the morphological diagnosis of mesothelioma.     

Effect of PEEP and Tidal Volume on Ventilation Distribution and End-Expiratory Lung Volume: A Prospective Experimental Animal and Pilot Clinical Study

Introduction

Lung-protective ventilation aims at using low tidal volumes (V_T) at optimum positive end-expiratory pressures (PEEP). Optimum PEEP should recruit atelectatic lung regions and avoid tidal recruitment and end-inspiratory overinflation. We examined the effect of V_T and PEEP on ventilation distribution, regional respiratory system compliance (C_RS), and end-expiratory lung volume (EELV) in an animal model of acute lung injury (ALI) and patients with ARDS by using electrical impedance tomography (EIT) with the aim to assess tidal recruitment and overinflation.

Methods

EIT examinations were performed in 10 anaesthetized pigs with normal lungs ventilated at 5 and 10 ml/kg body weight V_T and 5 cmH₂O PEEP. After ALI induction, 10 ml/kg V_T and 10 cmH₂O PEEP were applied. Afterwards, PEEP was set according to the pressure-volume curve. Animals were randomized to either low or high V_T ventilation changed after 30 minutes in a crossover design. Ventilation distribution, regional C_RS and changes in EELV were analyzed. The same measures were determined in five ARDS patients examined during low and high V_T ventilation (6 and 10 (8) ml/kg) at three PEEP levels.

Results

In healthy animals, high compared to low V_T increased C_RS and ventilation in dependent lung regions implying tidal recruitment. ALI reduced C_RS and EELV in all regions without changing ventilation distribution. Pressure-volume curve-derived PEEP of 21±4 cmH₂O (mean±SD) resulted in comparable increase in C_RS in dependent and decrease in non-dependent regions at both V_T. This implied that tidal recruitment was avoided but end-inspiratory overinflation was present irrespective of V_T. In patients, regional C_RS differences between low and high V_T revealed high degree of tidal recruitment and low overinflation at 3±1 cmH₂O PEEP. Tidal recruitment decreased at 10±1 cmH₂O and was further reduced at 15±2 cmH₂O PEEP.

Conclusions

Tidal recruitment and end-inspiratory overinflation can be assessed by EIT-based analysis of regional C_RS.     

Ancient Dispersal of the Human Fungal Pathogen Cryptococcus gattii from the Amazon Rainforest

Over the past two decades, several fungal outbreaks have occurred, including the high-profile ‘Vancouver Island’ and ‘Pacific Northwest’ outbreaks, caused by Cryptococcus gattii, which has affected hundreds of otherwise healthy humans and animals. Over the same time period, C. gattii was the cause of several additional case clusters at localities outside of the tropical and subtropical climate zones where the species normally occurs. In every case, the causative agent belongs to a previously rare genotype of C. gattii called AFLP6/VGII, but the origin of the outbreak clades remains enigmatic. Here we used phylogenetic and recombination analyses, based on AFLP and multiple MLST datasets, and coalescence gene genealogy to demonstrate that these outbreaks have arisen from a highly-recombining C. gattii population in the native rainforest of Northern Brazil. Thus the modern virulent C. gattii AFLP6/VGII outbreak lineages derived from mating events in South America and then dispersed to temperate regions where they cause serious infections in humans and animals.     

A short C-terminal tail prevents mis-targeting of hydrophobic mitochondrial membrane proteins to the ER

Sdh3/Shh3, a subunit of mitochondrial succinate dehydrogenase, contains transmembrane domains with a hydrophobicity comparable to that of endoplasmic reticulum (ER) proteins. Here, we show that a C-terminal reporter fusion to Sdh3/Shh3 results in partial mis-targeting of the protein to the ER. This mis-targeting is mediated by the signal recognition particle (SRP) and depends on the length of the C-terminal tail. These results imply that if nuclear-encoded mitochondrial proteins contain strongly hydrophobic transmembrane domains and a long C-terminal tail, they have the potential to be recognized by SRP and mis-targeted to the ER.     

Sporoderm in Populus and Salix

Four phenomena were observed in a study of Populus tremula and P. tremula f. gigas microspores from before microspore mitosis through mature pollen which may have general significance in the ontogeny of pollen grains: 1) The exine and orbicules (Ubisch bodies) were covered by membranes. 2) The exine and the tapetal surfaces where orbicules form were covered by a polysaccharide (PAS positive) coat until after microspore mitosis; subsequently the tapetum became plasmodial. 3) Material having the staining characteristics of the nexine 2 (endexine in the sense of Fægri) accumulated on membranes in microspores in the space between the exine and the plasma membrane. That material was almost completely gone from the wall in mature pollen. The membranes on which material had accumulated migrated through the exine. Following passage through the exine these membranes were seen as empty fusiform vesicles in micrographs of anthers prepared by commonly used methods. 4) At about microspore mitosis when the cellulosic intine begins to form, microtubules about 240 A in diameter occurred near the plasma membrane and generally parallel with it. Positive acid phosphatase reactions in tapetal cells together with the morphology of orbicules and other tapetal organelles suggest that the wall of orbicules, which is like the pollen exine, may form as a residual product of a lysosome system.

Sections of mature Salix humilis pollen were compared with Populus.