Metabolic footprint of epiphytic bacteria on Arabidopsis thaliana leaves

The phyllosphere, which is defined as the parts of terrestrial plants above the ground, is a large habitat for different microorganisms that show a high extent of adaption to their environment. A number of hypotheses were generated by culture-independent functional genomics studies to explain the competitiveness of specialized bacteria in the phyllosphere. In contrast, in situ data at the metabolome level as a function of bacterial colonization are lacking. Here, we aimed to obtain new insights into the metabolic interplay between host and epiphytes upon colonization of Arabidopsis thaliana leaves in a controlled laboratory setting using environmental metabolomics approaches. Quantitative nuclear magnetic resonance (NMR) and imaging high-resolution mass spectrometry (IMS) methods were used to identify Arabidopsis leaf surface compounds and their possible involvement in the epiphytic lifestyle by relative changes in compound pools. The dominant carbohydrates on the leaf surfaces were sucrose, fructose and glucose. These sugars were significantly and specifically altered after epiphytic leaf colonization by the organoheterotroph Sphingomonas melonis or the phytopathogen Pseudomonas syringae pv. tomato, but only to a minor extent by the methylotroph Methylobacterium extorquens. In addition to carbohydrates, IMS revealed surprising alterations in arginine metabolism and phytoalexin biosynthesis that were dependent on the presence of bacteria, which might reflect the consequences of bacterial activity and the recognition of not only pathogens but also commensals by the plant. These results highlight the power of environmental metabolomics to aid in elucidating the molecular basis underlying plant–epiphyte interactions in situ.     

Lymphocytic Infiltration of Epithelium in Diagnosis of Gluten-sensitive Enteropathy

The macroscopic appearance of the mucosa of the small intestine and the lymphocytic infiltration of the epithelium were studied in 27 patients with dermatitis herpetiformis and in 11 control subjects. The mucosa was abnormal in appearance in 13 of the patients and normal in 14 patients and in all the controls. In 25 (93%) of the patients the intraepithelial lymphocyte count was significantly raised compared with the controls. The increased lymphocytic infiltration of the epithelium in the patients probably represented an underlying immunological reaction of the small intestine to gluten, since the infiltration lessened in five out of six patients after a year on a gluten-free diet and in all of four patients after three years on a gluten-free diet.Increased lymphocytic infiltration of the epithelium of the small intestine seems a surer sign of gluten sensitivity than the macroscopic appearance of the mucosa, and a diagnosis of gluten-sensitive enteropathy may no longer be excluded when the mucosa appears normal. Further evidence of the significance of increased lymphocytic infiltration is that patients with normal-looking mucosa but with raised intraepithelial lymphocyte counts often had low serum folate levels.     

Splenic Atrophy in Dermatitis Herpetiformis

Twenty-four patients with dermatitis herpetiformis were investigated for splenic atrophy by splenic scan and clearance of ⁵¹Cr-labelled heat-damaged red blood cells. Eight of them had definite splenic atrophy. The average splenic cross-sectional area of the remaining 16 with normal clearance times was substantially smaller than normal, suggesting some degree of splenic atrophy. No relationship of splenic hypofunction to intestinal biopsy findings, folate status, reticulin antibody, or treatment with a gluten-free diet or dapsone was evident.     

Development and Testing of a Magnetically Actuated Capsule Endoscopy for Obesity Treatment

Intra-gastric balloons (IGB) have become an efficient and less invasive method for obesity treatment. The use of traditional IGBs require complex insertion tools and flexible endoscopes to place and remove the balloon inside the patient’s stomach, which may cause discomfort and complications to the patient. This paper introduces a new ingestible weight-loss capsule with a magnetically remote-controlled inflatable and deflatable balloon. To inflate the balloon, biocompatible effervescent chemicals are used. As the source of the actuation is provided via external magnetic fields, the magnetic capsule size can be significantly reduced compared to current weight-loss capsules in the literature. In addition, there are no limitations on the power supply. To lose weight, the obese subject needs only to swallow the magnetic capsule with a glass of water. Once the magnetic capsule has reached the patient’s stomach, the balloon will be wirelessly inflated to occupy gastric space and give the feeling of satiety. The balloon can be wirelessly deflated at any time to allow the magnetic capsule to travel down the intestine and exit the body via normal peristalsis. The optimal ratio between the acid and base to provide the desired gas volume is experimentally evaluated and presented. A prototype capsule (9.6mm x 27mm) is developed and experimentally validated in ex-vivo experiments. The unique ease of delivery and expulsion of the proposed magnetic capsule is slated to make this development a good treatment option for people seeking to lose excess weight.     

Protein-protein interactions and substrate channeling in orthologous and chimeric aldolase-dehydrogenase complexes

Bacterial aldolase-dehydrogenase complexes catalyze the last steps in the meta cleavage pathway of aromatic hydrocarbon degradation. The aldolase (TTHB246) and dehydrogenase (TTHB247) from Thermus thermophilus were separately expressed and purified from recombinant Escherichia coli. The aldolase forms a dimer, while the dehydrogenase is a monomer; these enzymes can form a stable tetrameric complex in vitro, consisting of two aldolase and two dehydrogenase subunits. Upon complex formation, the K(m) value of 4-hydroxy-2-oxopentanoate, the substrate of TTHB246, is decreased 4-fold while the K(m) of acetaldehyde, the substrate of TTHB247, is increased 3-fold. The k(cat) values of each enzyme were reduced by ~2-fold when they were in a complex. The half-life of TTHB247 at 50 °C increased by ~4-fold when it was in a complex with TTHB246. The acetaldehyde product from TTHB246 could be efficiently channelled directly to TTHB247, but the channeling efficiency for the larger propionaldehyde was ~40% lower. A single A324G substitution in TTHB246 increased the channeling efficiency of propionaldehyde to a value comparable to that of acetaldehyde. Stable and catalytically competent chimeric complexes could be formed between the T. thermophilus enzymes and the orthologous aldolase (BphI) and dehydrogenase (BphJ) from the biphenyl degradation pathway of Burkholderia xenovorans LB400. However, channeling efficiencies for acetaldehyde in these chimeric complexes were ~10%. Structural and sequence analysis suggests that interacting residues in the interface of the aldolase-dehydrogenase complex are highly conserved among homologues, but coevolution of partner enzymes is required to fine-tune this interaction to allow for efficient substrate channeling.     

Human serum promotes the proliferation but not the stemness genes expression of human adipose-derived stem cells

Recently human adipose-derived stem cells (ASCs) have shown much therapeutic potential in regenerative medicine. However, fetal bovine serum (FBS) used in culturing human cells may give risk to viral and prion transmission as well as immune rejection. Human serum (HS) is a safer growth supplement in human cell culture but its effects have not been well established. Therefore the objectives of this study were to compare the effects of HS versus FBS on the proliferation and stemness gene expression of ASCs. ASCs were cultured for 5 passages in medium supplemented with either 10% HS or 10% FBS. ASCs proliferation rate and viability were determined at every passage. Total RNA was extracted at passage 5 (P5) and quantitative PCR was carried out to determine the stemness gene expression level of SOX-2, Nanog3, BST-1, REX-1, ABCG2 and FGF-4. The results showed ASC cultured in 10% HS scored greater proliferation rates and viability compared to 10% FBS. ASCs proliferated significantly faster in 10% HS compared to 10% FBS at P2, P3, and P4 (p < 0.05). In quantitative gene expression analysis, ASCs cultured in 10% FBS showed a significant increase of BST-1, REX-1 and ABCG2 expression compared to 10% HS. In conclusion, HS promotes ASCs proliferation and viability but its ability to support the stemness property of ASCs was inferior to FBS.     

Multilocus population genetic analysis of the Southwest Pacific malaria vector Anopheles punctulatus

The population structure and history of the cryptic malaria vector species, Anopheles punctulatus (Doenitz), was investigated throughout Papua New Guinea and the Solomon Islands with the aim of detailing genetic subdivisions and the potential for movement through this biogeographically complex region. We obtained larval collections from over 80 sites and utilised a diverse array of molecular markers that evolve through different processes. Individuals were initially identified to species and genotyped using the ribosomal DNA second internal transcribed spacer. DNA sequencing of a single copy nuclear ribosomal protein S9 and the mitochondrial cytochrome oxidase I loci were then investigated and 12 nuclear microsatellite markers were developed and analysed. Our data revealed three genetically distinct populations – one in Papua New Guinea, the second on Buka Island (Bougainville Province, Papua New Guinea), and the third on Guadalcanal Island (Solomon Islands). Genetic differentiation within Papua New Guinea was much lower than that found in studies of other closely related species in the region. The data does suggest that A. punctulatus has undergone a population bottleneck followed by a recent population and range expansion in Papua New Guinea. Humans and regional economic growth may be facilitating this population expansion, as A. punctulatus is able to rapidly occupy human modified landscapes and traverse unsealed roads. We therefore anticipate extensive movement of this species through New Guinea – particularly into the highlands, with a potential increase in malaria frequency in a warming climate – as well as relatively unrestricted gene flow of advantageous alleles that may confound vector control efforts.     

Seipin regulates excitatory synaptic transmission in cortical neurons

Heterozygosity for missense mutations in Seipin, namely N88S and S90L, leads to a broad spectrum of motor neuropathy, while a number of loss‐of‐function mutations in Seipin are associated with the Berardinelli–Seip congenital generalized lipodystrophy type 2 (CGL2, BSCL2), a condition that is characterized by severe lipoatrophy, insulin resistance, and intellectual impairment. The mechanisms by which Seipin mutations lead to motor neuropathy, lipodystrophy, and insulin resistance, and the role Seipin plays in central nervous system (CNS) remain unknown. The goal of this study is to understand the functions of Seipin in the CNS using a loss‐of‐function approach, i.e. by knockdown (KD) of Seipin gene expression. Excitatory post‐synaptic currents (EPSCs) were impaired in Seipin‐KD neurons, while the inhibitory post‐synaptic currents (IPSCs) remained unaffected. Expression of a shRNA‐resistant human Seipin rescued the impairment of EPSC produced by Seipin KD. Furthermore, α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionic acid (AMPA)‐induced whole‐cell currents were significantly reduced in Seipin KD neurons, which could be rescued by expression of a shRNA‐resistant human Seipin. Fluorescent imaging and biochemical studies revealed reduced level of surface AMPA receptors, while no obvious ultrastructural changes in the pre‐synapse were found. These data suggest that Seipin regulates excitatory synaptic function through a post‐synaptic mechanism.