Invasive pulmonary aspergillosis due to a mixed infection caused by Aspergillus flavus and Aspergillus fumigatus

Invasive pulmonary aspergillosis is typically caused by a single Aspergillus species, most frequently Aspergillus fumigatus. Here we report that a lung transplant recipient developed invasive aspergillosis due to a mixed infection caused by Aspergillus flavus and A. fumigatus. The implications for this unusual finding are discussed.     

Comparative Proteomic Analysis of Supportive and Unsupportive Extracellular Matrix Substrates for Human Embryonic Stem Cell Maintenance

Human embryonic stem cells (hESCs) are pluripotent cells that have indefinite replicative potential and the ability to differentiate into derivatives of all three germ layers. hESCs are conventionally grown on mitotically inactivated mouse embryonic fibroblasts (MEFs) or feeder cells of human origin. In addition, feeder-free culture systems can be used to support hESCs, in which the adhesive substrate plays a key role in the regulation of stem cell self-renewal or differentiation. Extracellular matrix (ECM) components define the microenvironment of the niche for many types of stem cells, but their role in the maintenance of hESCs remains poorly understood. We used a proteomic approach to characterize in detail the composition and interaction networks of ECMs that support the growth of self-renewing hESCs. Whereas many ECM components were produced by supportive and unsupportive MEF and human placental stromal fibroblast feeder cells, some proteins were only expressed in supportive ECM, suggestive of a role in the maintenance of pluripotency. We show that identified candidate molecules can support attachment and self-renewal of hESCs alone (fibrillin-1) or in combination with fibronectin (perlecan, fibulin-2), in the absence of feeder cells. Together, these data highlight the importance of specific ECM interactions in the regulation of hESC phenotype and provide a resource for future studies of hESC self-renewal.     

Vaccine-Induced Boosting of Influenza Virus-Specific CD4 T Cells in Younger and Aged Humans

Current yearly influenza virus vaccines induce strain-specific neutralizing antibody (NAb) responses providing protective immunity to closely matched viruses. However, these vaccines are often poorly effective in high-risk groups such as the elderly and challenges exist in predicting yearly or emerging pandemic influenza virus strains to include in the vaccines. Thus, there has been considerable emphasis on understanding broadly protective immunological mechanisms for influenza virus. Recent studies have implicated memory CD4 T cells in heterotypic immunity in animal models and in human challenge studies. Here we examined how influenza virus vaccination boosted CD4 T cell responses in younger versus aged humans. Our results demonstrate that while the magnitude of the vaccine-induced CD4 T cell response and number of subjects responding on day 7 did not differ between younger and aged subjects, fewer aged subjects had peak responses on day 14. While CD4 T cell responses were inefficiently boosted against NA, both HA and especially nucleocaspid protein- and matrix-(NP+M) specific responses were robustly boosted. Pre-existing CD4 T cell responses were associated with more robust responses to influenza virus NP+M, but not H1 or H3. Finally pre-existing strain-specific NAb decreased the boosting of CD4 T cell responses. Thus, accumulation of pre-existing influenza virus-specific immunity in the form of NAb and cross-reactive T cells to conserved virus proteins (e.g. NP and M) over a lifetime of exposure to infection and vaccination may influence vaccine-induced CD4 T cell responses in the aged.     

Isolation and characterization of a hemocyte aggregation inhibitor from hemolymph of Manduca sexta larvae

A protein that inhibits hemocyte aggregation has been isolated from hemolymph of Manduca sexta larvae and named hemocyte aggregation inhibitor protein (HAIP). HAIP has a M_r = 50,000, pI = 8.5, and contains 7% carbohydrate. It is present at 230 ± 20 μg/ml in hemolymph of day 3 fifth instar larvae. Antibodies to HAIP do not cross-react with M. sexta hemolin, which is similar in size and charge and also inhibits hemocyte aggregation. HAIP and hemolin have some similarity in amino acid composition and NH₂-terminal sequence, but are different in overall secondary structure, as determined by CD spectroscopy. The concentration of HAIP in hemolymph is not affected by injection of larvae with bacteria. A protein of approximately 50,000 daltons that reacts with antibody to M. sexta HAIP is present in hemolymph of Bombyx mori, Heliothis zea, and Galleria mellonella. Although the function of HAIP in vivo is not yet clear, it may have a role in modulating adhesion of hemocytes during defensive responses. © 1994 Wiley-Liss, Inc.     

Discordance between morphological and molecular species boundaries among Caribbean species of the reef sponge Callyspongia

Sponges are among the most species‐rich and ecologically important taxa on coral reefs, yet documenting their diversity is difficult due to the simplicity and plasticity of their morphological characters. Genetic attempts to identify species are hampered by the slow rate of mitochondrial sequence evolution characteristic of sponges and some other basal metazoans. Here we determine species boundaries of the Caribbean coral reef sponge genus Callyspongia using a multilocus, model‐based approach. Based on sequence data from one mitochondrial (COI), one ribosomal (28S), and two single‐copy nuclear protein‐coding genes, we found evolutionarily distinct lineages were not concordant with current species designations in Callyspongia. While C. fallax, C. tenerrima, and C. plicifera were reciprocally monophyletic, four taxa with different morphologies (C. armigera, C. longissima, C. eschrichtii, and C. vaginalis) formed a monophyletic group and genetic distances among these taxa overlapped distances within them. A model‐based method of species delimitation supported collapsing these four into a single evolutionary lineage. Variation in spicule size among these four taxa was partitioned geographically, not by current species designations, indicating that in Callyspongia, these key taxonomic characters are poor indicators of genetic differentiation. Taken together, our results suggest a complex relationship between morphology and species boundaries in sponges.     

Characterization and clinical manifestations of Arcanobacterium phocae infections in marine mammals stranded along the central California coast

Between 1994 and 2000, 141 Arcanobacterium phocae isolates were recovered from marine mammals that stranded along the central California coast (USA). Arcanobacterium phocae was cultured from tissue sites with abnormal discharge or evidence of inflammation in 66 California sea lions (Zalophus californianus), 50 Pacific harbor seals (Phoca vitulina richardii), 19 northern elephant seals (Mirounga angustirostris), five southern sea otters (Enhydra lutris nereis), and one common dolphin (Delphinus delphis). The overall prevalence of A. phocae among cultured stranded marine mammals was 8%. This is the first report of A. phocae in animals from the Pacific Ocean. Sequence analysis of a portion of the 16S ribosomal RNA gene confirmed recent isolates as A. phocae. Prior to phylogenetic testing and the routine use of the esculin hydrolysis and motility tests, A. phocae isolates may have been misidentified as Listeria ivanovii. Arcanobacterium phocae was commonly isolated from superficial abscesses, was often present in mixed infections, and was susceptible to all antimicrobial agents tested.     

Asymmetric Segregation of the Double-Stranded RNA Binding Protein Staufen2 during Mammalian Neural Stem Cell Divisions Promotes Lineage Progression

Asymmetric cell divisions are a fundamental feature of neural development, and misregulation can lead to brain abnormalities or tumor formation. During an asymmetric cell division, molecular determinants are segregated preferentially into one daughter cell to specify its fate. An important goal is to identify the asymmetric determinants in neural progenitor cells, which could be tumor suppressors or inducers of specific neural fates. Here, we show that the double-stranded RNA-binding protein Stau2 is distributed asymmetrically during progenitor divisions in the developing mouse cortex, preferentially segregating into the Tbr2(+) neuroblast daughter, taking with it a subset of RNAs. Knockdown of Stau2 stimulates differentiation and overexpression produces periventricular neuronal masses, demonstrating its functional importance for normal cortical development. We immunoprecipitated Stau2 to examine its cargo mRNAs, and found enrichment for known asymmetric and basal cell determinants, such as Trim32, and identified candidates, including a subset involved in primary cilium function.