Hypobranching Induced by Both Environmental Antioxidants and ROS Metabolism Gene Knockouts in Neurospora Crassa

Previous work suggested a role of reactive oxygen species (ROS) metabolism on branch density, the statistical distribution of physical distances between branch points along a growing hypha in Neurospora. Here we report the results of experiments designed to ask more generally about the relationship between ROS and branch density by examining the branching effects of selected ROS metabolism gene knockout mutants as well as the impact on branching of exogenously added antioxidants. In all ROS metabolism mutants tested, growth was shown to branch less densely (hypobranching) when grown at lower temperatures, a shift not observed in the wild-type. Interestingly, this holds true for knockouts of genes expected to reduce ROS as well as those expected to produce them. In addition, in tests on wild type Neurospora, added ascorbic acid produced unusual branching patterns. Hypha exposed to exogenous antioxidants display dose dependent hypobranching with hypha becoming more hypobranched as doses increase. At higher doses, however, the branch distribution becomes bimodal with one maximum continuing to shift toward hypobranching and the second maximum representing a spike of very closely spaced branch points

Effect of Media and Estrogen on Morphological Change in Candida albicans

Introduction: Candida albicans (C. albicans), an opportunistic pathogen, lives symbiotically within the intestine of its human host. Temperature and chemical factors have been shown to induce a morphological change in C. albicans from yeast to filamentous form turning C. albicans pathogenic. In this study, we investigated the intestinal cues that might be responsible for the change. We found that different solid media impact the morphological phenotype so we focused on characterizing these before further testing. We tested Estradiol (E2) because of its known linkage to sepsis and higher levels during infections. Experiments were conducted to compare solid agar plates of YEPD, Minimal Media (MM), and Spider Media (SP) for C. albicans growth to choose the best one for further testing with E2 and other factors that could be prone to causing morphological changes. Methods: C. albicans was inoculated through streak method on different solid media (YEPD, MM, SP) and incubated at 30℃. The effect of 0.1nM E2 on C. albicans morphology was also tested. Morphological changes were assayed through bright-field microscopy. Results: Using the three different medias, we found three distinctive phenotypes: A, B, and C. Out of 6 experiments of 14 MM plates, the expressed phenotype was 86% A and 14% inconclusive of the time. 8 experiments of 17 SP plates showed 100% of phenotype B. 6 experiments of 14 YEPD plates presented phenotype C 92% of the time and 8% inconclusive. For E2 trials, 2 experiments, 6 MM plates showed 50% phenotype A and 50% inconclusive. 4 experiments, 10 SP plates had phenotype B 100%. YEPD 2 experiments, 2 plates had phenotype C at 100%. Conclusion: We have established experimental conditions of media controls for further testing whether E2 and other cues, such as inflammatory cytokines, have inhibitory or positive effects on the growth of C. albicans

The Effects of Low and High Gravity on Neurospora Crassa

We studied the effects of different gravity levels on Neurospora crassa and its morphology. This research was conducted by simulating low and high gravity effects in different operating procedures. For the low gravity simulation, the experiment was conducted by using a clinostat to constantly disorient the samples at a very slow rate. For the high gravity simulation, N. crassa was subjected to different amounts of g forces by placing the samples in a centrifuge and subjected the samples to increasing amounts of revolutions per minute. The results of these experiments conclude that in low-gravity situations, the N. crassa showed sparse growth and some cytoplasmic failure. In the high gravity situations, the samples showed that at around 1,000 to 2,000 RPMs, there were no changes in the morphology, but at higher RPMs like 3,000 or 4,000, there were some signs of cytoplasmic failure but no noticeable changes to morphology

Students perceptions of cheating in online business courses

Accounting majors enrolled in business courses at two different universities were asked to complete a survey questionnaire pertaining to cheating in online business courses. Specifically, students majoring in Accounting were asked about their awareness online business courses as well as their opinions regarding the credibility of online courses and the effectiveness of different techniques that may be used to prevent cheating. Forty-six percent of students indicated that they had knowledge of students receiving help with an online exam/quiz. Overall, 75 percent of respondents indicated that the most effective technique to prevent cheating on online exams/quizzes is the use of random question generation so every exam is uniquely different. Forty-two percent of respondents disagreed with the statement “Online courses are less credible than traditional courses.” While the potential for cheating in online courses seems to be well perceived, the perception of actual cheating in online courses seems to vary considerable among the students covered in this study

Strain-Dependent Relationship Between Growth Rate and Hyphal Branching in Neurospora Crassa

In a previous study of branch frequency in Neurospora crassa focused on the wild-type, no relationship between growth rate and the frequency of hyphal branching was observed. In subsequent experiments, it became clear that while this independence is valid for the wild type and most mutant strains, it fails to hold for a subset of morphological mutants. This study distinguishes a subset of Neurospora morphological mutants for their morphological response to altered growth rate. Growth rates are altered using two different methods: reduced temperature and nutrient-deficient media. This should assure that the observed effect is not due to simple conditional mutations in the mutant strains examined. The observed effect provides an additional method for characterizing morphological mutants. It also provides support for models of branching in which control of branching is tightly linked to mechanisms of tip growth

Testing the Potential of Using Fungi to Convert Human Waste into Protein

We report on the results of a pilot experiment designed to test the potential of filamentous fungi (mold) to reduce solid waste (feces) while converting it into a consumable, high protein food product. Feces represent an untapped resource. Filamentous fungi are natural decomposers with the ability to use this resource. Many filamentous fungi are safe to eat. We examined growth in order to determine the conditions which maximized the rate of conversion of solid waste into fungal biomass. For this pilot, we compared the effect of different lengths of incubation, different methods of aeration, and different available surface area. The initial study resulted in rates of conversion as high as 75% (3.75g of mold produced from 5g of solid waste). Fungal growth also appeared to reduce odor. Although initially proposed as a mechanism to deal with waste and food storage issues on long-term space missions, this project holds the potential to benefit waste processing in diverse situations including large livestock confinement operations and sewage treatment facilities. This work was supported by a grant from the Indiana Space Grant Consortium (INSGC)

Effect of Media and Estrogen on Morphological Change in Candida albicans

Introduction: Candida albicans (C. albicans), an opportunistic pathogen, lives symbiotically within the intestine of its human host. Temperature and chemical factors have been shown to induce a morphological change in C. albicans from yeast to filamentous form turning C. albicans pathogenic. In this study, we investigated the intestinal cues that might be responsible for the change. We found that different solid media impact the morphological phenotype so we focused on characterizing these before further testing. We tested Estradiol (E2) because of its known linkage to sepsis and higher levels during infections. Experiments were conducted to compare solid agar plates of YEPD, Minimal Media (MM), and Spider Media (SP) for C. albicans growth to choose the best one for further testing with E2 and other factors that could be prone to causing morphological changes. Methods: C. albicans was inoculated through streak method on different solid media (YEPD, MM, SP) and incubated at 30℃. The effect of 0.1nM E2 on C. albicans morphology was also tested. Morphological changes were assayed through bright-field microscopy. Results: Using the three different medias, we found three distinctive phenotypes: A, B, and C. Out of 6 experiments of 14 MM plates, the expressed phenotype was 86% A and 14% inconclusive of the time. 8 experiments of 17 SP plates showed 100% of phenotype B. 6 experiments of 14 YEPD plates presented phenotype C 92% of the time and 8% inconclusive. For E2 trials, 2 experiments, 6 MM plates showed 50% phenotype A and 50% inconclusive. 4 experiments, 10 SP plates had phenotype B 100%. YEPD 2 experiments, 2 plates had phenotype C at 100%. Conclusion: We have established experimental conditions of media controls for further testing whether E2 and other cues, such as inflammatory cytokines, have inhibitory or positive effects on the growth of C. albicans

The Contribution of Fermi Gamma-Ray Pulsars to the local Flux of Cosmic-Ray Electrons and Positrons

We analyze the contribution of gamma-ray pulsars from the first Fermi-Large Area Telescope (LAT) catalogue to the local flux of cosmic-ray electrons and positrons (e+e-). We present new distance estimates for all Fermi gamma-ray pulsars, based on the measured gamma-ray flux and pulse shape. We then estimate the contribution of gamma-ray pulsars to the local e+e- flux, in the context of a simple model for the pulsar e+e- emission. We find that 10 of the Fermi pulsars potentially contribute significantly to the measured e+e- flux in the energy range between 100 GeV and 1 TeV. Of the 10 pulsars, 2 are old EGRET gamma-ray pulsars, 2 pulsars were discovered with radio ephemerides, and 6 were discovered with the Fermi pulsar blind-search campaign. We argue that known radio pulsars fall in regions of parameter space where the e+e- contribution is predicted to be typically much smaller than from those regions where Fermi-LAT pulsars exist. However, comparing the Fermi gamma-ray flux sensitivity to the regions of pulsar parameter space where a significant e+e- contribution is predicted, we find that a few known radio pulsars that have not yet been detected by Fermi can also significantly contribute to the local e+e- flux if (i) they are closer than 2 kpc, and if (ii) they have a characteristic age on the order of one mega-year.Comment: 21 pages, 6 figures, accepted for publication in JCA

The Seventh Data Release of the Sloan Digital Sky Survey

This paper describes the Seventh Data Release of the Sloan Digital Sky Survey (SDSS), marking the completion of the original goals of the SDSS and the end of the phase known as SDSS-II. It includes 11663 deg^2 of imaging data, with most of the roughly 2000 deg^2 increment over the previous data release lying in regions of low Galactic latitude. The catalog contains five-band photometry for 357 million distinct objects. The survey also includes repeat photometry over 250 deg^2 along the Celestial Equator in the Southern Galactic Cap. A coaddition of these data goes roughly two magnitudes fainter than the main survey. The spectroscopy is now complete over a contiguous area of 7500 deg^2 in the Northern Galactic Cap, closing the gap that was present in previous data releases. There are over 1.6 million spectra in total, including 930,000 galaxies, 120,000 quasars, and 460,000 stars. The data release includes improved stellar photometry at low Galactic latitude. The astrometry has all been recalibrated with the second version of the USNO CCD Astrograph Catalog (UCAC-2), reducing the rms statistical errors at the bright end to 45 milli-arcseconds per coordinate. A systematic error in bright galaxy photometr is less severe than previously reported for the majority of galaxies. Finally, we describe a series of improvements to the spectroscopic reductions, including better flat-fielding and improved wavelength calibration at the blue end, better processing of objects with extremely strong narrow emission lines, and an improved determination of stellar metallicities. (Abridged)Comment: 20 pages, 10 embedded figures. Accepted to ApJS after minor correction