Anti-proliferation of Melanoma Cells and Immune Stimulation by the Cyanobacterial Indole-alkaloid Scytonemin

Under the stress of ultraviolet radiation some cyanobacteria synthesize scytonemin, a protective pigment against DNA photodamage. In addition to photoprotection, scytonemin has been shown to have an anti-proliferative effect on various types of malignant cells. In this study the effect of scytonemin on melanoma and spleen cells was assessed both in vitro using tissue cultures and in vivo in mice models. Melanoma and spleen cells were exposed to 0.08 to 10 μM of scytonemin, and cell proliferation was measured using tritiated thymidine uptake. The data suggest that scytonemin acts as an inhibitor for melanoma cells in a concentration-dependent manner while enhancing the proliferation of spleen cells, suggesting that it can potentially augment the immune response. Furthermore, mice injected with melanoma cells and scytonemin produced fewer tumors than mice that did not receive scytonemin, although the data were not significant. This study adds to the growing body of research that scytonemin may be beneficial as a future anticancer agent to prevent tumor cell growth.

Isolation and Identification of Dermatophytes from Collegiate Runners

Competitive runners experience various risk factors that render them more susceptible to superficial cutaneous fungal infections, including the use of occlusive footwear, shared locker rooms, submission of feet to constant maceration, trauma, sweating, and having depressed immune function. The goal of this work was to assess the prevalence of athlete’s foot fungi in cross country runners at St. John Fisher College. Toe webs of 16 collegiate runners were sampled and volunteers surveyed about their shoe habits, foot hygiene, and average miles run per week. Lack of tinea pedis-causing fungi in asymptomatic cross- country runners shifted the study to investigate the identities of fungi morphologically similar to athlete’s foot and look for correlations with volunteers’ running habits and hygiene. Thirty-five distinct fungal cultures were isolated and compared to a known Trichophyton rubrum strain both microscopically and macroscopically. Four samples were preliminarily identified as tinea pedis-causing fungi and sequenced to confirm molecular identification. Fungal DNA was isolated, purified, and PCR amplified using primers for the internal transcribed spacer region, D1/D2 region of the 28S subunit, and β-Tubulin gene. Three of the four isolates were identified as Fusarium equiseti, a soil-borne plant pathogen with rare human pathogenicity reported. The fourth isolate was Beauveria bassiana, a common soil-borne pathogen that can infect immunocompromised individuals. Correct dermatophytic identification and understanding of the interplay between species is important to provide correct treatment, prevent spread among athletes and within facilities, and determine how opportunistic pathogens might play a role in people with immune suppressed function, which includes runners.

Biogenesis of Lipoproteins in Gram-Negative Bacteria: 50 Years of Progress

The outer membrane is the defining characteristic of Gram-negative bacteria and is crucial for the maintenance of cellular integrity. Lipoproteins are an essential component of this outer membrane and regulate broad cellular functions ranging from efflux, cellular physiology, antibiotic resistance, and pathogenicity. In the canonical model of lipoprotein biogenesis, lipoprotein precursors are first synthesized in the cytoplasm prior to extensive modifications by the consecutive action of three key enzymes: diacylglyceryl transferase (Lgt), lipoprotein signal peptidase A (LspA), and apolipoprotein N-acyltransferase (Lnt). This enzymatic process modifies lipoprotein precursors for subsequent trafficking by the Lol pathway. The function of these three enzymes were originally thought to be essential, however, in some Gram-negative bacteria, namely Acinetobacter baylyi, the third enzyme Lnt is dispensable. Here we review the function and significance of Lgt, LspA, and Lnt in outer membrane biogenesis and how non-canonical models of lipoprotein processing in Acinetobacter spp. can enhance our understanding of lipoprotein modifications and trafficking.

Real-time Screening of Foods Using Repetitive Element PCR Reveals a DNA Marker Characteristic for Enterotoxigenic Bacillus Species

Bacillus cereus is traditionally thought to be the only member of its genus accepted as a pathogen in foods like grains, fruits, vegetables, and milk due to the presence of the nonhemolytic (Nhe) operon. However, many other Bacillus spp. may also harbor the Nhe operon and be pathogenic, including not just food-associated gastrointestinal toxicoinfections, but human endophthalmitis as well. Real-time PCR targeted the nheA gene in 37 samples obtained from food, soil, and reference cultures by analyzing the standard deviations of melt peaks. Repetitive element PCR was used to compare the banding patterns of each sample against B. cereus ATCC 14579 and three B. thuringiensis strains to “fingerprint” each isolate. Of the original 43 isolated tested, 37 were Gram-positive rods. The remaining six samples were Gram-positive cocci. Twenty-five of the 37 Gram-positive Bacillus spp. were nheA positive, while twelve were negative. Many of the nheA positive strains were species not previously known to contain Nhe and were capable of causing gastroenteritis in consumers.

Nylon Oxygen Barrier Tubing Reduces Biofouling in Beer Draught Lines

Beer draught lines are frequently contaminated with biofilm-forming microorganisms, which forces retailers to spend considerable time and money cleaning and replacing lines. In light of this financial burden, draught tubing composition was examined for its role in the prevention of biofouling in beer lines. Three types of draught tubing - vinyl, polyethylene, and nylon barrier - were inoculated with a combination of biofilm-forming microorganisms (Hafnia paralvei, Raoultella planticola, Pediococcus damnosus and Saccharomyces cerevisiae) and used to simulate a bar environment for sixteen weeks. Following simulation, the degree of biofouling in each draught line was determined by spectrophotometry and microscopy. Absorption values and fluorescence images showed that nylon barrier tubing was superior to the other lines at resisting biofilm maturation.These results suggest that tubing composition plays a significant role in the prevention of biofilm formation in beer draught lines and supports the adoption of nylon barrier tubing as an effective strategy against biofouling in a variety of applications.

Factors Affecting Learning Gains among Students in Microbiology Class: A Preliminary Study Between a U.S. Community College and a Canadian Comprehensive University

Though in the past, serious concerns have been raised about students’ interest and learning gains in STEM courses, not much research has been done to examine the differences in learning science at community colleges and universities. The purpose of this paper is to close this gap. This paper analyzes the influence of students’ demographics, preparedness, major, and attitudes on their learning gains in an introductory microbiology class at a community college vs. a university. Student demographics, information about their preparedness level, major, and attitudes were collected in a questionnaire and students’ learning gains were assessed by comparing student performance on a pre- and post-test on four different topics in microbiology. Our results indicate that students’ majors and attitudes such as their willingness to actively participate in the classroom discussions and spend time outside the classroom to learn are major factors that enhance their learning. Age and marital status positively impact learning gains while gender, employment status, and citizenship status show no impact on learning gains in students. Our results also indicate that students at the community college who had less exposure to science classes in high school or biology classes in college achieved statistically higher learning gains despite having overall lower scores on two of the four post-tests.

Addressing the global antibiotic resistance crisis through a microbiology undergraduate course-based research experience (CURE)

Objective Lens by editor Dr. John McKillip

A Pre-Med Graduate’s Gap Year of Community Immersion: Finding a Greater Purpose

Undergraduate Student Perspective

Loss of protein quality control gene UBR1 sensitizes Saccharomyces cerevisiae to the aminoglycoside hygromycin B

Ubr1 is a conserved ubiquitin ligase involved in the degradation of aberrant proteins in eukaryotic cells. The human enzyme is found mutated in patients with Johanson-Blizzard syndrome. We hypothesized that Ubr1 is necessary for optimal cellular fitness in conditions associated with elevated abundance of aberrant and misfolded proteins. Indeed, we found that loss of Ubr1 in the model eukaryotic microorganism Saccharomyces cerevisiae strongly sensitizes cells to hygromycin B, which reduces translational fidelity by causing ribosome A site distortion. Our results are consistent with a prominent role for Ubr1 in protein quality control. We speculate that disease manifestations in patients with Johanson-Blizzard syndrome are linked, at least in part, to defects in protein quality control caused by loss of Ubr1 function.

The benefits of mentoring undergraduate research students

Faculty Perspective by Dr. Douglas H. Roossien