Quantitative analysis of harmonic convergence in mosquito auditory interactions

This article analyses the hearing and behaviour of mosquitoes in the context of inter-individual acoustic interactions. The acoustic interactions of tethered live pairs of Aedes aegypti mosquitoes, from same and opposite sex mosquitoes of the species, are recorded on independent and unique audio channels, together with the response of tethered individual mosquitoes to playbacks of pre-recorded flight tones of lone or paired individuals. A time-dependent representation of each mosquito's non-stationary wing beat frequency signature is constructed, based on Hilbert spectral analysis. A range of algorithmic tools is developed to automatically analyse these data, and used to perform a robust quantitative identification of the 'harmonic convergence' phenomenon. The results suggest that harmonic convergence is an active phenomenon, which does not occur by chance. It occurs for live pairs, as well as for lone individuals responding to playback recordings, whether from the same or opposite sex. Male-female behaviour is dominated by frequency convergence at a wider range of harmonic combinations than previously reported, and requires participation from both partners in the duet. New evidence is found to show that male-male interactions are more varied than strict frequency avoidance. Rather, they can be divided into two groups: convergent pairs, typified by tightly bound wing beat frequencies, and divergent pairs, that remain widely spaced in the frequency domain. Overall, the results reveal that mosquito acoustic interaction is a delicate and intricate time-dependent active process that involves both individuals, takes place at many different frequencies, and which merits further enquiry

Semaphorin 7A plays a critical role in TGF-β1–induced pulmonary fibrosis

Semaphorin (SEMA) 7A regulates neuronal and immune function. In these studies, we tested the hypothesis that SEMA 7A is also a critical regulator of tissue remodeling. These studies demonstrate that SEMA 7A and its receptors, plexin C1 and β1 integrins, are stimulated by transforming growth factor (TGF)-β1 in the murine lung. They also demonstrate that SEMA 7A plays a critical role in TGF-β1–induced fibrosis, myofibroblast hyperplasia, alveolar remodeling, and apoptosis. TGF-β1 stimulated SEMA 7A via a largely Smad 3–independent mechanism and stimulated SEMA 7A receptors, matrix proteins, CCN proteins, fibroblast growth factor 2, interleukin 13 receptor components, proteases, antiprotease, and apoptosis regulators via Smad 2/3–independent and SEMA 7A–dependent mechanisms. SEMA 7A also played an important role in the pathogenesis of bleomycin-induced pulmonary fibrosis. TGF-β1 and bleomycin also activated phosphatidylinositol 3-kinase (PI3K) and protein kinase B (PKB)/AKT via SEMA 7A–dependent mechanisms, and PKB/AKT inhibition diminished TGF-β1–induced fibrosis. These observations demonstrate that SEMA 7A and its receptors are induced by TGF-β1 and that SEMA 7A plays a central role in a PI3K/PKB/AKT-dependent pathway that contributes to TGF-β1–induced fibrosis and remodeling. They also demonstrate that the effects of SEMA 7A are not specific for transgenic TGF-β1, highlighting the importance of these findings for other fibrotic stimuli

Analysis of Water Surplus at the Lunar Outpost

This paper evaluates the benefits to the lunar architecture and outpost of having a surplus of water, or a surplus of energy in the form of hydrogen and oxygen, as it has been predicted by Constellation Program's Lunar Surface System analyses. Assumptions and a scenario are presented leading to the water surplus and the revolutionary surface element options for improving the lunar exploration architecture and mission objectives. For example, some of the elements that can benefit from a water surplus are: the power system energy storage can minimize the use of battery systems by replacing batteries with higher energy density fuel cell systems; battery packs on logistics pallets can also be minimized; mobility asset power system mass can be reduced enabling more consumables and extended roving duration and distance; small robotic vehicles (hoppers) can be used to increase the science exploration range by sending round-trip robotic missions to anywhere on the Moon using in-situ produced propellants

Early Growth Response Gene 1–mediated Apoptosis Is Essential for Transforming Growth Factor β1–induced Pulmonary Fibrosis

Fibrosis and apoptosis are juxtaposed in pulmonary disorders such as asthma and the interstitial diseases, and transforming growth factor (TGF)-β1 has been implicated in the pathogenesis of these responses. However, the in vivo effector functions of TGF-β1 in the lung and its roles in the pathogenesis of these responses are not completely understood. In addition, the relationships between apoptosis and other TGF-β1–induced responses have not been defined. To address these issues, we targeted bioactive TGF-β1 to the murine lung using a novel externally regulatable, triple transgenic system. TGF-β1 produced a transient wave of epithelial apoptosis that was followed by mononuclear-rich inflammation, tissue fibrosis, myofibroblast and myocyte hyperplasia, and septal rupture with honeycombing. Studies of these mice highlighted the reversibility of this fibrotic response. They also demonstrated that a null mutation of early growth response gene (Egr)-1 or caspase inhibition blocked TGF-β1–induced apoptosis. Interestingly, both interventions markedly ameliorated TGF-β1–induced fibrosis and alveolar remodeling. These studies illustrate the complex effects of TGF-β1 in vivo and define the critical role of Egr-1 in the TGF-β1 phenotype. They also demonstrate that Egr-1–mediated apoptosis is a prerequisite for TGF-β1–induced fibrosis and remodeling

Oncogenic EGFR Represses the TET1 DNA Demethylase to Induce Silencing of Tumor Suppressors in Cancer Cells

SummaryOncogene-induced DNA methylation-mediated transcriptional silencing of tumor suppressors frequently occurs in cancer, but the mechanism and functional role of this silencing in oncogenesis are not fully understood. Here, we show that oncogenic epidermal growth factor receptor (EGFR) induces silencing of multiple unrelated tumor suppressors in lung adenocarcinomas and glioblastomas by inhibiting the DNA demethylase TET oncogene family member 1 (TET1) via the C/EBPα transcription factor. After oncogenic EGFR inhibition, TET1 binds to tumor suppressor promoters and induces their re-expression through active DNA demethylation. Ectopic expression of TET1 potently inhibits lung and glioblastoma tumor growth, and TET1 knockdown confers resistance to EGFR inhibitors in lung cancer cells. Lung cancer samples exhibited reduced TET1 expression or TET1 cytoplasmic localization in the majority of cases. Collectively, these results identify a conserved pathway of oncogenic EGFR-induced DNA methylation-mediated transcriptional silencing of tumor suppressors that may have therapeutic benefits for oncogenic EGFR-mediated lung cancers and glioblastomas

Bostonia: The Boston University Alumni Magazine. Volume 9

Founded in 1900, Bostonia magazine is Boston University's main alumni publication, which covers alumni and student life, as well as university activities, events, and programs

Chandra Observation of V426 Oph: Weighing the Evidence for a Magnetic White Dwarf

We report the results of a 45 ks Chandra observation of the cataclysmic variable V426 Ophiuchus. The high resolution spectrum from the high-energy transmission grating spectrometer is most consistent with a cooling flow model, placing V426 Oph among the group of CVs including U Gem and EX Hya. An uninterrupted lightcurve was also constructed, in which we detect a significant 4.2 hr modulation together with its first harmonic at 2.1 hrs. Reanalysis of archival Ginga, and ROSAT X-ray lightcurves also reveals modulations at periods consistent with 4.2 and/or 2.1 hrs. Furthermore, optical photometry in V, simultaneous with the Chandra observation, indicates a modulation anti-correlated with the X-ray, and later more extensive R band photometry finds a signal at ~2.1 hrs. The earlier reported X-ray periods at ~0.5 and 1 hrs appear to be only transient and quasi-periodic in nature. In contrast, the 4.2 hr period or its harmonic are stable and persistent in X-ray/optical data from 1988 to 2003. This periodicity is clearly distinct from the 6.85 hr orbit, and could be due to the spin of the white dwarf. If this is the case, V426 Oph would be the first long period intermediate polar with a ratio P_spin/P_orb of 0.6. However, this interpretation requires unreasonable values of magnetic field strength and mass accretion rate.Comment: 11 pages, 7 figures, 5 tables. Accepted for publication in the Astrophysical Journal (to appear August 2004