Apoplastic Venom Allergen-like Proteins of Cyst Nematodes Modulate the Activation of Basal Plant Innate Immunity by Cell Surface Receptors

Despite causing considerable damage to host tissue during the onset of parasitism, nematodes establish remarkably persistent infections in both animals and plants. It is thought that an elaborate repertoire of effector proteins in nematode secretions suppresses damage-triggered immune responses of the host. However, the nature and mode of action of most immunomodulatory compounds in nematode secretions are not well understood. Here, we show that venom allergen-like proteins of plant-parasitic nematodes selectively suppress host immunity mediated by surface-localized immune receptors. Venom allergen-like proteins are uniquely conserved in secretions of all animal- and plant-parasitic nematodes studied to date, but their role during the onset of parasitism has thus far remained elusive. Knocking-down the expression of the venom allergen-like protein Gr-VAP1 severely hampered the infectivity of the potato cyst nematode Globodera rostochiensis. By contrast, heterologous expression of Gr-VAP1 and two other venom allergen-like proteins from the beet cyst nematode Heterodera schachtii in plants resulted in the loss of basal immunity to multiple unrelated pathogens. The modulation of basal immunity by ectopic venom allergen-like proteins in Arabidopsis thaliana involved extracellular protease-based host defenses and non-photochemical quenching in chloroplasts. Non-photochemical quenching regulates the initiation of the defense-related programmed cell death, the onset of which was commonly suppressed by venom allergen-like proteins from G. rostochiensis, H. schachtii, and the root-knot nematode Meloidogyne incognita. Surprisingly, these venom allergen-like proteins only affected the programmed cell death mediated by surface-localized immune receptors. Furthermore, the delivery of venom allergen-like proteins into host tissue coincides with the enzymatic breakdown of plant cell walls by migratory nematodes. We, therefore, conclude that parasitic nematodes most likely utilize venom allergen-like proteins to suppress the activation of defenses by immunogenic breakdown products in damaged host tissue.     

Anchored protein kinase A signalling in cardiac cellular electrophysiology

The cyclic adenosine monophosphate (cAMP)‐dependent protein kinase (PKA) is an elementary molecule involved in both acute and chronic modulation of cardiac function. Substantial research in recent years has highlighted the importance of A‐kinase anchoring proteins (AKAP) therein as they act as the backbones of major macromolecular signalling complexes of the β‐adrenergic/cAMP/PKA pathway. This review discusses the role of AKAP‐associated protein complexes in acute and chronic cardiac modulation by dissecting their role in altering the activity of different ion channels, which underlie cardiac action potential (AP) generation. In addition, we review the involvement of different AKAP complexes in mechanisms of cardiac remodelling and arrhythmias.     

Genetic Variability of Plasmodium malariae dihydropteroate synthase (dhps) in Four Asian Countries

The dihydropteroate synthase (dhps) genes of 44 P. malariae strains from four Asian countries were isolated. Only a limited number of polymorphisms were observed. Comparison with homologous mutations in other Plasmodium species showed that these polymorphisms are unlikely to be associated with sulfadoxine resistance.     

Human Immunoglobulin Repertoires against Tetanus Toxoid Contain a Large and Diverse Fraction of High-Affinity Promiscuous VH Genes

To study the contribution of antibody light (L) chains to the diversity and binding properties of immune repertoires, a phage display repertoire was constructed from a single human antibody L chain and a large collection of antibody heavy (H) chains harvested from the blood of two human donors immunized with tetanus toxoid (TT) vaccine. After selection for binding to TT, 129 unique antibodies representing 53 variable immunoglobulin H chain (V_H) gene rearrangements were isolated. This panel of anti-TT antibodies restricted to a single variable immunoglobulin L chain (V_L) could be organized into 17 groups binding non-competing epitopes on the TT molecule. Comparison of the V_H regions in this V_L-restricted panel with a previously published repertoire of anti-TT V_H regions with cognate V_H-V_L pairing showed a very similar distribution of V_H, D_H and J_H gene segment utilization and length of the complementarity-determining region 3 of the H chain. Surface plasmon resonance analysis of the single-V_L anti-TT repertoire unveiled a range of affinities, with a median monovalent affinity of 2 nM. When the single-V_L anti-TT V_H repertoire was combined with a collection of naïve V_L regions and again selected for binding to TT, many of the V_H genes were recovered in combination with a diversity of V_L regions. The affinities of a panel of antibodies consisting of a single promiscuous anti-TT V_H combined with 15 diverse V_L chains were determined and found to be identical to each other and to the original isolate restricted to a single-V_L chain. Based on previous estimates of the clonal size of the human anti-TT repertoire, we conclude that up to 25% of human anti-TT-encoding V_H regions from an immunized repertoire have promiscuous features. These V_H regions readily combine with a single antibody L chain to result in a large panel of anti-TT antibodies that conserve the expected epitope diversity, V_H region diversity and affinity of a natural repertoire.     

Modeling conversion and transport phenomena in solid-state fermentation: a review and perspectives

Solid-state fermentation (SSF) is accompanied inevitably by development of concentration and temperature gradients within the substrate particles and microbial biofilms. These gradients are needed for driving the transport of substrates and products. In addition, concentration gradients have been suggested to be crucial for obtaining the characteristics that define the products of SSF; nevertheless, gradients are also known to result in reduced productivity and unwanted side reactions. Solid-state fermentations are generally batch processes and this further complicates their understanding as conditions change with time. Mathematical models are therefore needed for improving the understanding of SSF processes and allowing their manipulation to achieve the desired outcomes. Existing models of SSF processes describe coupled substrate conversion and diffusion and the consequent microbial growth. Existing models disregard many of the significant phenomena that are known to influence SSF. As a result, available models cannot explain the generation of the numerous products that form during any SSF process and the outcome of the process in terms of the characteristics of the final product. This review critically evaluates the proposed models and their experimental validation. In addition, important issues that need to be resolved for improved modeling of SSF are discussed.     

Envisioning the reward

The primary visual cortex (area V1) is for vision. At least, that is what most researchers believe. However, in a recent issue of Science, Shuler and Bear demonstrate a correlate of reward timing in area V1. This surprising result indicates that brain circuits for reward processing are more extensive than expected and that area V1 has more functionality than previously thought.     

Analysis of the cGMP/cAMP interactome using a chemical proteomics approach in mammalian heart tissue validates sphingosine kinase type 1-interacting protein as a genuine and highly abundant AKAP

The cyclic nucleotide monophosphates cAMP and cGMP play an essential role in many signaling pathways. To analyze which proteins do interact with these second messenger molecules, we developed a chemical proteomics approach using cAMP and cGMP immobilized onto agarose beads, via flexible linkers in the 2- and 8-position of the nucleotide. Optimization of the affinity pull-down procedures in lysates of HEK293 cells revealed that a large variety of proteins could be pulled down specifically. Identification of these proteins by mass spectrometry showed that many of these proteins were indeed genuine cAMP or cGMP binding proteins. However, additionally many of the pulled-down proteins were more abundant AMP/ADP/ATP, GMP/GDP/GTP, or general DNA/RNA binding proteins. Therefore, a sequential elution protocol was developed, eluting proteins from the beads using solutions containing ADP, GDP, cGMP, and/or cAMP, respectively. Using this protocol, we were able to sequentially and selectively elute ADP, GDP, and DNA binding proteins. The fraction left on the beads was further enriched, for cAMP/cGMP binding proteins. Transferring this protocol to the analysis of the cGMP/cAMP "interactome" in rat heart ventricular tissue enabled the specific pull-down of known cAMP/cGMP binding proteins such as cAMP and cGMP dependent protein kinases PKA and PKG, several phosphodiesterases and 6 AKAPs, that interact with PKA. Among the latter class of proteins was the highly abundant sphingosine kinase type1-interating protein (SKIP), recently proposed to be a potential AKAP. Further bioinformatics analysis endorses that SKIP is indeed a genuine PKA interacting protein, which is highly abundant in heart ventricular tissue.