Malaria sporozoite antigen‐directed genome‐wide response in transgenic Drosophila

Malaria kills a million people annually. Understanding the relationship between a causative parasite, Plasmodium falciparum, and the mosquito vector might suggest novel prevention approaches. We created and transformed into Drosophila two genes encoding, thrombospondin‐related adhesive protein (TRAP) and circumsporozoite protein (CSP), found on the cell surface of Plasmodium sporozoites. To understand a model insect's response, we induced these proteins separately and together, performing whole genome microarray analysis measuring gene expression changes. Gene ontology classification of responding genes reveals that TRAP and CSP strongly and differentially influence Drosophila genes involved with cell motility and gene regulation, respectively; however, the most striking effects are on the immune system. While immune‐related genes are but modestly elevated compared with responses to sepsis, there is a marked repression of the Toll pathway. This suggests: (1) how Plasmodium infection of the mosquito might use TRAP and CSP to modulate the host insect's physiology to promote sporozoite survival and transmission to man and (2) that approaches to elevate expression of the mosquito's Toll pathway might lead to novel methods of malaria prevention. genesis 47:196–203, 2009. © 2009 Wiley‐Liss, Inc.     

Exogenous maltose enhances Zebrafish immunity to levofloxacin-resistant Vibrio alginolyticus

Understanding the interplay between bacterial fitness, antibiotic resistance, host immunity and host metabolism could guide treatment and improve immunity against antibiotic-resistant pathogens. The acquisition of levofloxacin (Lev) resistance affects the fitness of Vibrio alginolyticus in vitro and in vivo. Lev-resistant (Lev-R) V. alginolyticus exhibits slow growth, reduced pathogenicity and greater resistance to killing by the host, Danio rerio (zebrafish), than Lev-sensitive (Lev-S) V. alginolyticus, suggesting that Lev-R V. alginolyticus triggers a weaker innate immune response in D. rerio than Lev-S V. alginolyticus. Differences were detected in the metabolome of D. rerio infected with Lev-S or Lev-R V. alginolyticus. Maltose, a crucial metabolite, is significantly downregulated in D. rerio infected with Lev-R V. alginolyticus, and exogenous maltose enhances the immune response of D. rerio to Lev-R V. alginolyticus, leading to better clearance of the infection. Furthermore, we demonstrate that exogenous maltose stimulates the host production of lysozyme and its binding to Lev-R V. alginolyticus, which depends on bacterial membrane potential. We suggest that exogenous exposure to crucial metabolites could be an effective strategy for treating and/or managing infections with antibiotic-resistant bacteria.     

Effects of culture conditions on osteogenic differentiation in human mesenchymal stem cells

Human bone marrow-derived mesenchymal stem cells (hBMMSCs) must differentiate into osteogenic cells to allow for successful bone regeneration. In this study, we investigated the effects of different combinations of three soluble osteogenic differentiation-inducing factors [L-ascorbic acid (AC), beta-glycerophosphate (betaG), and bone morphogenic protein-2 (BMP-2)] and the presence of a hydroxyapatite (HA) substrate on hBMMSC osteogenic differentiation in vitro. hBMMSCs were cultured in medium containing various combinations of the soluble factors on culture plates with or without HA coating. After 7 days of culture, alkaline phosphatase (ALP) activity, calcium deposition, and osteoprotegerin (OPG) and osteopontin (OPN) expression were measured. The effects of individual and combined factors were evaluated using a factorial analysis method. BMP-2 predominantly affected expression of early markers of osteogenic differentiation (ALP and OPG). HA had the highest positive effect on OPN expression and calcium deposition. The interaction between AC, betaG, and HA had the second highest positive effect on ALP activity.     

The Interactions of Glutathione-Capped CdTe Quantum Dots with Trypsin

Due to their unique fluorescent properties, quantum dots present a great potential for biolabelling applications; however, the toxic interactions of quantum dots with biopolymers are little known. The toxic interactions of glutathione-capped CdTe quantum dots with trypsin were studied in this paper using synchronous fluorescence spectroscopy, fluorescence emission spectra, and UV–vis absorption spectra. The interaction between CdTe quantum dots and trypsin resulted in structure changes of trypsin and inhibited trypsin's activity. Fluorescence emission spectra revealed that the quenching mechanism of trypsin by CdTe quantum dots was a static quenching process. The binding constant and the number of binding sites at 288 and 298 K were calculated to be 1.98 × 10⁶ L mol⁻¹ and 1.37, and 6.43 × 10⁴ L mol⁻¹ and 1.09, respectively. Hydrogen bonds and van der Waals' forces played major roles in this process.     

High-resolution mapping of genotype-phenotype relationships in cri du chat syndrome using array comparative genomic hybridization

We have used array comparative genomic hybridization to map DNA copy-number changes in 94 patients with cri du chat syndrome who had been carefully evaluated for the presence of the characteristic cry, speech delay, facial dysmorphology, and level of mental retardation (MR). Most subjects had simple deletions involving 5p (67 terminal and 12 interstitial). Genotype-phenotype correlations localized the region associated with the cry to 1.5 Mb in distal 5p15.31, between bacterial artificial chromosomes (BACs) containing markers D5S2054 and D5S676; speech delay to 3.2 Mb in 5p15.32-15.33, between BACs containing D5S417 and D5S635; and the region associated with facial dysmorphology to 2.4 Mb in 5p15.2-15.31, between BACs containing D5S208 and D5S2887. These results overlap and refine those reported in previous publications. MR depended approximately on the 5p deletion size and location, but there were many cases in which the retardation was disproportionately severe, given the 5p deletion. All 15 of these cases, approximately two-thirds of the severely retarded patients, were found to have copy-number aberrations in addition to the 5p deletion. Restriction of consideration to patients with only 5p deletions clarified the effect of such deletions and suggested the presence of three regions, MRI-III, with differing effect on retardation. Deletions including MRI, a 1.2-Mb region overlapping the previously defined cri du chat critical region but not including MRII and MRIII, produced a moderate level of retardation. Deletions restricted to MRII, located just proximal to MRI, produced a milder level of retardation, whereas deletions restricted to the still-more proximal MRIII produced no discernible phenotype. However, MR increased as deletions that included MRI extended progressively into MRII and MRIII, and MR became profound when all three regions were deleted.