Metabolome profiling reveals metabolic cooperation between Bacillus megaterium and Ketogulonicigenium vulgare during induced swarm motility

The metabolic cooperation in the ecosystem of Bacillus megaterium and Ketogulonicigenium vulgare was investigated by cultivating them spatially on a soft agar plate. We found that B. megaterium swarmed in a direction along the trace of K. vulgare on the agar plate. Metabolomics based on gas chromatography coupled with time-of-flight mass spectrometry (GC-TOF-MS) was employed to analyze the interaction mechanism between the two microorganisms. We found that the microorganisms interact by exchanging a number of metabolites. Both intracellular metabolism and cell-cell communication via metabolic cooperation were essential in determining the population dynamics of the ecosystem. The contents of amino acids and other nutritional compounds in K. vulgare were rather low in comparison to those in B. megaterium, but the levels of these compounds in the medium surrounding K. vulgare were fairly high, even higher than in fresh medium. Erythrose, erythritol, guanine, and inositol accumulated around B. megaterium were consumed by K. vulgare upon its migration. The oxidization products of K. vulgare, including 2-keto-gulonic acids (2KGA), were sharply increased. Upon coculturing of B. megaterium and K. vulgare, 2,6-dipicolinic acid (the biomarker of sporulation of B. megaterium), was remarkably increased compared with those in the monocultures. Therefore, the interactions between B. megaterium and K. vulgare were a synergistic combination of mutualism and antagonism. This paper is the first to systematically identify a symbiotic interaction mechanism via metabolites in the ecosystem established by two isolated colonies of B. megaterium and K. vulgare.     

真菌中脱落酸的代谢及定量分析技术

综述了各种脱落酸产生真菌的生物学特征及其不同的生物合成代谢途径,并对脱落酸的定量分析技术作了简要介绍。     

Determination of albuterol in plasma after aerosol inhalation by gas chromatography-mass spectrometry with selected-ion monitoring

Albuterol is a β₂-adrenergic agonist commonly used as a bronchdilator for the treatment of patients with asthma. We have developed an assay to determine plasma levels as low as 50 pg/ml of albuterol by gas chromatography-mass spectrometry (GC-MS). This assay utilizes isotopically labeled albuterol ([¹³C]albuterol) as an internal standard. In this assay albuterol and the internal standard are recovered from 1 ml of plasma using solid-phase extraction. The samples are then derivatized to trimethylsilyl ethers using N,O-bis(trimethylsilyl)trifluoro-acetamide with 1% trimethylchlorosilane. The samples are then analyzed by GC-MS with selected-ion monitoring (SIM) for the ions m/z 369.15 and 370.15. The method has been validated for a concentration range of 50–10000 pg/ml in plasma.     

EVALUATING THE IMPACT OF INSECT COMMUNITY ON PINE CATERPILLAR DENSITY IN DIFFERENT STAND CONDITIONS

Abstract  Natural enemies play an important role in inhibiting population growth of pine caterpillar, but they are difficult to be used in systematic management models. This paper attempts to use some forest stand factors to substitute the effect of natural enemies, which could be used in management models. Through the studies from more than 200 stand plots with different stand conditions in Qu County, Changshan County, and Longyou County of Zhejiang Province, 16 predominant species groups from insect community were selected, and the canonical correlation coefficient between the diversity index, species number, individual number of predominant species and the stand factors was analyzed. The results indicated that the canopy density and ground vegetation were the key stand factors for characterizing the function of insect community. The forest area was divided into four types according to the variation of canopy and vegetation conditions by using cluster analysis. The regression models between the rate of variation of pine caterpillar density and the forest factors including canopy density and vegetation covers were developed in each type of forests. There were significant differences in diversity index, species number, individual number of insect community and population density of pine caterpillar among four types of forests, and correlation coefficients of the four regression models were rather high ( r =0. 924 — 0. 964). This means that the classification of the forest stands is reasonable and the stand factors can characterize the effect of natural enemies in practice.     

Regional Distribution of Calmodulin Activity in Rat Brain

Calmodulin activity in 68 discrete areas of rat brain, obtained by micropunch technique, was assessed by its capacity to activate a calmodulin-sensitive form of phosphodiesterase. In general, the activity of calmodulin was higher in the telencephalon, limbic system, and hypothalamus than in the mesencephalon, pons, cerebellum, and medulla. However, there were substantial differences in calmodulin activity in discrete nuclei of each region. The regional distribution of calmodulin activity in rat brain does not appear to correlate with that of any of the known putative neurotransmitters or peptides.     

Hippocampal place cells acquire location-specific responses to the conditioned stimulus during auditory fear conditioning

We recorded neurons from the hippocampus of freely behaving rats during an auditory fear conditioning task. Rats received either paired or unpaired presentations of an auditory conditioned stimulus (CS) and an electric shock unconditioned stimulus (US). Hippocampal neurons (place and theta cells) acquired responses to the auditory CS in the paired but not in the unpaired group. After CS-US pairing, rhythmic firing of theta cells became synchronized to the onset of the CS. Conditioned responses of place cells were gated by their location-specific firing, so that after CS-US pairing, place cells responded to the CS only when the rat was within the cell's place field. These findings may help to elucidate how the hippocampus contributes to context-specific memory formation during associative learning.     

TRAIL-R2 (DR5) mediates apoptosis of synovial fibroblasts in rheumatoid arthritis

TRAIL has been proposed as an anti-inflammatory cytokine in animal models of rheumatoid arthritis (RA). Using two agonistic mAbs specific for TRAIL-R1 (DR4) and TRAIL-R2 (DR5), we examined the expression and function of these death receptors in RA synovial fibroblast cells. The synovial tissues and primary synovial fibroblast cells isolated from patients with RA, but not those isolated from patients with osteoarthritis, selectively expressed high levels of cell surface DR5 and were highly susceptible to anti-DR5 Ab (TRA-8)-mediated apoptosis. In contrast, RA synoviocytes did not show increased expression of TRAIL-R1 (DR4), nor was there any difference in expression of Fas between RA and osteoarthritis synovial cells. In vitro TRA-8 induced apoptosis of RA synovial cells and inhibited production of matrix metalloproteinases induced by pro-inflammatory cytokines. In vivo TRA-8 effectively inhibited hypercellularity of a SV40-transformed RA synovial cell line and completely prevented bone erosion and cartilage destruction induced by these cells. These results indicate that increased DR5 expression and susceptibility to DR5-mediated apoptosis are characteristic of the proliferating synovial cells in RA. As highly proliferative transformed-appearing RA synovial cells play a crucial role in bone erosion and cartilage destruction in RA, the specific targeting of DR5 on RA synovial cells with an agonistic anti-DR5 Ab may be a potential therapy for RA.     

APP processing is regulated by cytoplasmic phosphorylation

Amyloid-beta peptide (Abeta) aggregate in senile plaque is a key characteristic of Alzheimer's disease (AD). Here, we show that phosphorylation of amyloid precursor protein (APP) on threonine 668 (P-APP) may play a role in APP metabolism. In AD brains, P-APP accumulates in large vesicular structures in afflicted hippocampal pyramidal neurons that costain with antibodies against endosome markers and the beta-secretase, BACE1. Western blot analysis reveals increased levels of T668-phosphorylated APP COOH-terminal fragments in hippocampal lysates from many AD but not control subjects. Importantly, P-APP cofractionates with endosome markers and BACE1 in an iodixanol gradient and displays extensive colocalization with BACE1 in rat primary cortical neurons. Furthermore, APP COOH-terminal fragments generated by BACE1 are preferentially phosphorylated on T668 verses those produced by alpha-secretase. The production of Abeta is significantly reduced when phosphorylation of T668 is either abolished by mutation or inhibited by T668 kinase inhibitors. Together, these results suggest that T668 phosphorylation may facilitate the BACE1 cleavage of APP to increase Abeta generation.