Correlation between temperature range of growth and structural transitions in membranes and lipids of Escherichia coli K12

Purified cytoplasmic and outer membranes isolated from cells of wild-type Escherichia coli grown at different temperatures were labelled with 1,6-diphenyl-1,3,5-hexatriene and anlyzed using fluorescence polarization techniques. Lipids extracted from the membranes were similarly analyzed using fluorescence polarization. The thermotropic structural transition in outer membranes changed as a function of growth temperature. The structural transition in cytoplasmic membranes and lipids extracted from either cytoplasmic or outer membranes did not change with growth temperature. These data suggest that adaptive changes which occur in the outer membrane determine the temperature range of growth of E. coli. These changes apparently require alterations in outer membrane components other than phospholipids.     

Intrathecal levels of matrix metalloproteinases in systemic lupus erythematosus with central nervous system engagement

Symptoms originating from the central nervous system (CNS) occur frequently in patients with systemic lupus erythematosus (SLE), and CNS involvement in lupus is associated with increased morbidity and mortality. We recently showed that neurones and astrocytes are continuously damaged during the course of CNS lupus. The matrix metalloproteinases (MMPs) are a group of tissue degrading enzymes that may be involved in this ongoing brain destruction. The aim of this study was to examine endogenous levels of free, enzymatically active MMP-2 and MMP-9 in cerebrospinal fluid from patients with SLE. A total of 123 patients with SLE were evaluated clinically, with magnetic resonance imaging of brain and cerebrospinal fluid (CSF) analyses. Levels of free MMP-2 and MMP-9 were determined in CSF using an enzymatic activity assay. CSF samples from another 22 cerebrally healthy individuals were used as a control. Intrathecal MMP-9 levels were significantly increased in patients with neuropsychiatric SLE as compared with SLE patients without CNS involvement (P < 0.05) and healthy control individuals (P = 0.0012). Interestingly, significant correlations between MMP-9 and intrathecal levels of neuronal and glial degradation products were noted, indicating ongoing intrathecal degeneration in the brains of lupus patients expressing MMP-9. In addition, intrathecal levels of IL-6 and IL-8 – two cytokines that are known to upregulate MMP-9 – both exhibited significant correlation with MMP-9 levels in CSF (P < 0.0001), suggesting a potential MMP-9 activation pathway. Our findings suggest that proinflammatory cytokine induced MMP-9 production leads to brain damage in patients with CNS lupus.     

Fatal-Mixed Cutaneous Zygomycosis–Aspergillosis: A Case Report

Mucorales and Aspergillus are molds responsible for infections in immunocompromised patients. In this report, we describe a case of a rare extensively mixed cutaneous infection caused by Lichtheimia ramosa, Aspergillus fumigatus and Aspergillus terreus in a neutropenic patient suffering from an acute leukemia. The fatal outcome of this patient can be attributed to its hematologic malignancy, the extensive nature of the lesions and the resistance of the strains to antifungals.     

Lion,Ungulate, and Visitor Reactions to Playbacks of Lion Roars at Zoo Atlanta

Felids in captivity are often inactive and elusive in zoos, leading to a frustrating visitor experience. Eight roars were recorded from an adult male lion and played back over speakers as auditory enrichment to benefit the lions while simultaneously enhancing the zoo visitor experience. In addition, ungulates in an adjacent exhibit were observed to ensure that the novel location and increased frequency of roars did not lead to a stress or fear response. The male lion in this study roared more in the playback phase than in the baseline phases while not increasing any behaviors that would indicate compromised welfare. In addition, zoo visitors remained at the lion exhibit longer during playback. The nearby ungulates never exhibited any reactions stronger than orienting to playbacks, identical to their reactions to live roars. Therefore, naturalistic playbacks of lion roars are a potential form of auditory enrichment that leads to more instances of live lion roars and enhances the visitor experience without increasing the stress levels of nearby ungulates or the lion themselves, who might interpret the roar as that of an intruder.     

Down-regulated expression of plant-specific glycoepitopes in alfalfa

Compared with other plant expression systems used for pharmaceutical protein production, alfalfa offers the advantage of very homogeneous N -glycosylation. Therefore, this plant was selected for further attempts at glycoengineering. Two main approaches were developed in order to humanize N -glycosylation in alfalfa. The first was a knock-down of two plant-specific N -glycan maturation enzymes, β1,2-xylosyltransferase and α1,3-fucosyltransferases, using sense, antisense and RNA interference strategies. In a second approach, with the ultimate goal of rebuilding the whole human sialylation pathway, human β1,4-galactosyltransferase was expressed in alfalfa in a native form or in fusion with a targeting domain from N -acetylglucosaminyltransferase I, a glycosyltransferase located in the early Golgi apparatus in Nicotiana tabacum . Both knock-down and knock-in strategies strongly, but not completely, inhibited the biosynthesis of α1,3-fucose- and β1,2-xylose-containing glycoepitopes in transgenic alfalfa. However, recombinant human β1,4-galactosyltransferase activity in transgenic alfalfa completely prevented the accumulation of the Lewis a glycoepitope on complex N -glycans.     

Regulation of the high affinity IgE receptor (Fc epsilonRI) in human neutrophils: role of seasonal allergen exposure and Th-2 cytokines

The high affinity IgE receptor, Fc epsilonRI, plays a key role in the immunological pathways involved in allergic asthma. Previously we have demonstrated that human neutrophils isolated from allergic asthmatics express a functional Fc epsilonRI, and therefore it was of importance to examine the factors regulating its expression. In this study, we found that neutrophils from allergic asthmatics showed increased expression of Fc epsilonRI-alpha chain surface protein, total protein and mRNA compared with those from allergic non asthmatics and healthy donors (p<0.001). Interestingly, in neutrophils isolated from allergic asthmatics, Fc epsilonRI-alpha chain surface protein and mRNA expression were significantly greater during the pollen season than outside the pollen season (n = 9, P = 0.001), an effect which was not observed either in the allergic non asthmatic group or the healthy donors (p>0.05). Allergen exposure did not affect other surface markers of neutrophils such as CD16/Fc gammaRIII or IL-17R. In contrast to stimulation with IgE, neutrophils incubated with TH2 cytokines IL-9, GM-CSF, and IL-4, showed enhanced Fc epsilonRI-alpha chain surface expression. In conclusion, these results suggest that enhanced Fc epsilonRI expression in human neutrophils from allergic asthmatics during the pollen season can make them more susceptible to the biological effects of IgE, providing a possible new mechanism by which neutrophils contribute to allergic asthma.     

Transferability,development of simple sequence repeat (SSR) markers and application to the analysis of genetic diversity and population structure of the African fan palm (Borassus aethiopum Mart.) in Benin

Biological pathways play an important role in the occurrence, development and recovery of complex diseases, such as cancers, which are multifactorial complex diseases that are generally caused by mutation of multiple genes or dysregulation of pathways. We propose a path-specific effect statistic (PSE) to detect the differential specific paths under two conditions (e.g. case VS. control groups, exposure Vs. nonexposure groups). In observational studies, the path-specific effect can be obtained by separately calculating the average causal effect of each directed edge through adjusting for the parent nodes of nodes in the specific path and multiplying them under each condition. Theoretical proofs and a series of simulations are conducted to validate the path-specific effect statistic. Applications are also performed to evaluate its practical performances. A series of simulation studies show that the Type I error rates of PSE with Permutation tests are more stable at the nominal level 0.05 and can accurately detect the differential specific paths when comparing with other methods. Specifically, the power reveals an increasing trends with the enlargement of path-specific effects and its effect differences under two conditions. Besides, the power of PSE is robust to the variation of parent or child node of the nodes on specific paths. Application to real data of Glioblastoma Multiforme (GBM), we successfully identified 14 positive specific pathways in mTOR pathway contributing to survival time of patients with GBM. All codes for automatic searching specific paths linking two continuous variables and adjusting set as well as PSE statistic can be found in supplementary materials.  The proposed PSE statistic can accurately detect the differential specific pathways contributing to complex disease and thus potentially provides new insights and ways to unlock the black box of disease mechanisms.     

A new role for C/EBPbeta in acute promyelocytic leukemia

The differentiating properties of retinoic acid (RA) have been used beneficially for the treatment of Acute Promyelocytic Leukemia (APL) for more than a decade. However, the molecular mechanisms of how RA induces APL cell differentiation are still poorly understood. In our previous work, we provided a novel mechanism to explain the unique sensitivity to RA of APL cells. We proposed that C/EBPbeta is an ATRA-dependent PML/RARA target gene and that its activation is critical during ATRA-induced differentiation of APL cells. Here, I discuss how C/EBPbeta could be an important gene in APL pathogenesis.     

The aqueous accessibility in the external half of transmembrane domain I of the GABA transporter GAT-1 Is modulated by its ligands

The sodium- and chloride-dependent gamma-aminobutyric acid (GABA) transporter GAT-1 is the first identified member of a family of transporters, which maintain low synaptic neurotransmitter levels and thereby enable efficient synaptic transmission. To obtain evidence for the idea that the highly conserved transmembrane domain I (TMD I) participates in the permeation pathway, we have determined the impact of impermeant methanethiosulfonate (MTS) reagents on cysteine residues engineered into this domain. As a background the essentially insensitive but fully active C74A mutant has been used. Transport activity of mutants with a cysteine introduced cytoplasmic to glycine 63 is largely unaffected and is resistant to the impermeant MTS reagents. Conversely, transport activity in mutants extracellular to glycine 63 is strongly impacted. Nevertheless, transport activity could be measured in all but three mutants: G65C, N66C, and R69C. In each of the six active cysteine mutants the activity is highly sensitive to the impermeant MTS reagents. This sensitivity is potentiated by sodium in L64C, F70C, and Y72C, but is protected in V67C and P71C. GABA protects in L64C, W68C, F70C, and P71C. The non-transportable GABA analogue SKF100330A also protects in L64C, W68C, and P71C as well as V67C, but strikingly potentiates inhibition in F70C. Although cysteine substitution in this region may have perturbed the native structure of GAT-1, our observations, taken together with the recently published accessibility study on the related serotonin transporter (Henry, L. K., Adkins, E. M., Han, Q., and Blakely, R. D. (2003) J. Biol. Chem. 278, 37052-37063), suggest that the extracellular part of TMD I is conformationally sensitive, lines the permeation pathway, and forms a more extended structure than expected from a membrane-embedded alpha-helix.