Pharmacologic modulation of RNA splicing enhances anti-tumor immunity

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Temporal dynamics of mating and predation in mosquito swarms

We determined the numbers of copulations and predatory attacks in swarms ofAnopheles freeborni (Diptera: Culicidae), and the distribution of these events throughout the duration of the swarming period each day. On 19 evenings of observation, we recorded 2724 copulating pairs leaving swarms and 1351 dragonfly (Pantala hymenaea andErythemis collocata) attacks. Mating activity partially coincided with predator activity. Most copulations occurred between 10 and 20 min after the swarms formed, while predation events were most frequent during the initial 15 min of the swarm. We calculated the ratio of copulations to predatory attacks during the swarming period. This ratio was significantly higher in an area sheltered by trees than it was in the open. We suggest that physiological and ecological constraints other than predation operate on the mating system of this anopheline to affect the timing of swarm initiation and swarm site selection.     

Isolation of a mannose-specific lectin from Escherichia coli and its role in the adherence of the bacteria to epithelial cells.

A high molecular weight protein aggregate, which agglutinates yeast cells, human epithelial cells and mouse lymphocytes, was isolated from extracts of Escherichia coli by differential centrifugation and gel filtration. The agglutination is specifically inhibited by d-mannose and its derivatives, the best inhibitor being p-nitrophenyl α-d-mannoside. Sodium dodecyl sulfate gel electrophoresis showed that the lectin consists of protein subunits with identical M_r of ～36500. The amino acid composition of the purified lectin is different from that reported for the type I pili protein, the K99 antigen and the major outer membrane protein Ia of E. coli. The protein appears to be located on the bacterial surface, and is probably involved in the mannose-specific adherence of E. coli to eukaryotic cells.     

Delayed Contrast Extravasation MRI for Depicting Tumor and Non-Tumoral Tissues in Primary and Metastatic Brain Tumors

The current standard of care for newly diagnosed glioblastoma multiforme (GBM) is resection followed by radiotherapy with concomitant and adjuvant temozolomide. Recent studies suggest that nearly half of the patients with early radiological deterioration post treatment do not suffer from tumor recurrence but from pseudoprogression. Similarly, a significant number of patients with brain metastases suffer from radiation necrosis following radiation treatments. Conventional MRI is currently unable to differentiate tumor progression from treatment-induced effects. The ability to clearly differentiate tumor from non-tumoral tissues is crucial for appropriate patient management. Ten patients with primary brain tumors and 10 patients with brain metastases were scanned by delayed contrast extravasation MRI prior to surgery. Enhancement subtraction maps calculated from high resolution MR images acquired up to 75 min after contrast administration were used for obtaining stereotactic biopsies. Histological assessment was then compared with the pre-surgical calculated maps. In addition, the application of our maps for prediction of progression was studied in a small cohort of 13 newly diagnosed GBM patients undergoing standard chemoradiation and followed up to 19.7 months post therapy. The maps showed two primary enhancement populations: the slow population where contrast clearance from the tissue was slower than contrast accumulation and the fast population where clearance was faster than accumulation. Comparison with histology confirmed the fast population to consist of morphologically active tumor and the slow population to consist of non-tumoral tissues. Our maps demonstrated significant correlation with perfusion-weighted MR data acquired simultaneously, although contradicting examples were shown. Preliminary results suggest that early changes in the fast volumes may serve as a predictor for time to progression. These preliminary results suggest that our high resolution MRI-based delayed enhancement subtraction maps may be applied for clear depiction of tumor and non-tumoral tissues in patients with primary brain tumors and patients with brain metastases.     

Identification and Localization of a Rickettsia sp. in Bemisia tabaci (Homoptera: Aleyrodidae)

Whiteflies (Homoptera: Aleyrodidae) are sap-sucking insects that harbor “Candidatus Portiera aleyrodidarum,” an obligatory symbiotic bacterium which is housed in a special organ called the bacteriome. These insects are also home for a diverse facultative microbial community which may include Hamiltonella, Arsenophonus, Fritchea, Wolbachia, and Cardinium spp. In this study, the bacteria associated with a B biotype of the sweet potato whitefly Bemisia tabaci were characterized using molecular fingerprinting techniques, and a Rickettsia sp. was detected for the first time in this insect family. Rickettsia sp. distribution, transmission and localization were studied using PCR and fluorescence in situ hybridizations (FISH). Rickettsia was found in all 20 Israeli B. tabaci populations screened but not in all individuals within each population. A FISH analysis of B. tabaci eggs, nymphs, and adults revealed a unique concentration of Rickettsia around the gut and follicle cells, as well as a random distribution in the hemolymph. We postulate that the Rickettsia enters the oocyte together with the bacteriocytes, leaves these symbiont-housing cells when the egg is laid, multiplies and spreads throughout the egg during embryogenesis and, subsequently, disperses throughout the body of the hatching nymph, excluding the bacteriomes. Although the role Rickettsia plays in the biology of the whitefly is currently unknown, the vertical transmission on the one hand and the partial within-population infection on the other suggest a phenotype that is advantageous under certain conditions but may be deleterious enough to prevent fixation under others.     

Thermobifida fusca family-6 cellulases as potential designer cellulosome components

During the course of our studies on the structure-function relationship of cellulosomes, we were interested in converting the free cellulase system of the aerobic bacterium, Thermobifida fusca, to a cellulosomal system. For this purpose, the cellulose-binding modules (CBM) of two T. fusca family-6 cellulases, endoglucanase Cel6A and exoglucanase Cel6B, were replaced by divergent dockerin modules. Thus far, family-6 cellulases have not been shown to be members of natural cellulosome systems. The resultant chimaeric proteins, 6A-c and t-6B, respectively, were purified and found to interact specifically and stoichiometrically with their corresponding cohesin modules, indicating their suitability for use as components in 'designer cellulosomes'. Both chimaeric enzymes showed somewhat decreased but measurable levels of activity on carboxymethyl cellulose, consistent with the known endo- and exo-glucanase character of the parent enzymes. The activity of 6A-c on phosphoric acid swollen cellulose was also consistent with that of the wild-type endoglucanase Cel6A. The startling finding of the present research was the extent of degradation of this substrate by the chimaeric enzyme t-6B. Wild-type exoglucanase Cel6B exhibited very low activity on this substrate, while the specific activity of t-6B was 14-fold higher than the parent enzyme.