The following student awards were presented at the 2007 In Vitro Biology Meeting, Indianapolis, Indiana. Information related to the available specific student awards can be found on the SIVB website (www.sivb.net) or by contacting the SIVB Business Office at (919) 420-7940, sivb@sivb.net, or Dr. Pamela Weathers, Chair, Student Affairs and Awards Committee, at (870) 680-4795, email: pweathers@astate.edu.

2007 CELLULAR TOXICOLOGY AWARD

Paloma Olvera-Caltzontzin

In Vitro Effect of Carotenoids on Breast Cancer Cells

Breast cancer is one of the first causes of mortality in women on reproductive age worldwide, and ductal breast cancer is the most common (80% of death). Some factors are associated with breast cancer risk, including nutritional factors, particularly antioxidant status. Between antioxidant compounds, carotenoids are abundant on fruits and vegetables. -carotene is the most common carotenoid however, lycopene from tomatoes is now consumed in approximately the same amount as -carotene. Epidemiological studies have shown an inverse relationship between carotenoid intake and cancer but, for breast cancer, results are inconsistent. The goal of this work was to determine the effect of -carotene and lycopene on proliferation and survival of ductal (ZR-75-1) and glandular (MCF-7) breast cancer cells. Dose-response curves showed that lycopene increased survival and proliferation of both cell lines, the effect was more pronounced on MCF-7 than on ZR-75-1 cells. On MCF-7 cells, the highest concentration tested of -carotene (1×10-4 M) exhibited cytostatic effect, and lower concentrations stimulated cell proliferation. On the other hand, there was an inhibitory effect of -carotene on ZR-75-1 cells, proliferation and survival were inhibited nearly 50% when cells were treated with 1×10-4 M of -carotene (p<0.05) and lower concentrations stimulated cell growth. Our results show that some carotenoids, but not all, can affect cell growth depending on carotenoid type and concentration. Also, we are demonstrating that ductal breast cancer cells are less resistant than glandular cells. Future studies will evaluate the possible mechanism of action of carotenoids on ductal breast cancer cells.

Paloma Olvera-Caltzontzin, Universidad Autonoma de Queretaro. Facultad de Ciencias Naturales. Queretaro. MEXICO. In Vitro Cellular and Developmental Biology, 43:S34, 2007


2007 SIVB STUDENT TRAVEL AWARD

Sukhpreet Sandhu

Generation, Characterization and Risk Assessment of Transgenic, Herbicide Resistant Forage and Turf Grass (Paspalum notatum Flugge).

Bahiagrass (Paspalum notatum Flugge) is one of the most important forage and low-input turf grasses in the southeastern United States. However, its open growth habit facilitates weed encroachment and its low tolerance to commercially available herbicides complicates weed management. ‘Argentine’, a commercially important bahiagrass cultivar was chosen for genetic transformation to incorporate glufosinate herbicide resistance. Its apomictic mode of reproduction should allow production of uniform seed progeny and might reduce the risk of unintended gene dispersal by pollen. To further investigate this, we co-transformed minimal unlinked nptII and bar expression constructs (MC’s) into bahiagrass callus by biolistic gene transfer. The vector backbone was removed prior gene transfer to enhance co-expression and expression stability and eliminate the prokaryotic antibiotic resistance expression cassette. Twenty-one nptII expressing plants were confirmed by ELISA following selection of 300 bombarded calli on paramomycin containing media. Relatively simple integration patterns for the nptII gene, and higher copy numbers and more complex integration patterns for the non-selected bar gene were detected by Southern blot analysis. Consistent with earlier reports the co-integration and co-expression frequency of the unlinked MC’s was higher than 90%. Integration of quantitative ELISA-, Southern blot- and herbicide resistance data under greenhouse and field conditions indicated that MC’s support high level expression of the bar gene and resistance to high glufosinate application rates. Molecular analysis of the seed progeny of the transgenic lines, will also be presented. Glufosinate resistance in apomictic ‘Argentine’ bahiagrass was used as a marker to study pollen-mediated intraspecific gene flow from transgenic apomictic ‘Argentine’ bahiagrass to wild type diploids under field and greenhouse conditions. Data on herbicide resistance of seed progeny, intraspecific gene transfer frequencies, ploidy, fertility and transgene integration patterns of gene transfer events will be presented.

Sukhpreet Sandhu, Agronomy Department, PMCB, Genetics Institute, University of Florida – IFAS, Gainesville, FL 32611. In Vitro Cellular and Developmental Biology, 43:S57-S58, 2007


2007 SIVB STUDENT TRAVEL AWARD

Tejas Gawade

In Vitro Evaluation of Pertussis Toxin Composite Nanofibers as a Non-Invasive Whooping Cough Vaccine

Global resurgence of pertussis (whooping cough) has raised questions about the current preventative and treatment technologies. As a highly contagious disease caused by the fastidious gram negative coccobacillus, Bordetella pertussis, whooping cough is primarily considered a pediatric illness. Recent trends show a shift in epidemiology towards adolescents and adults, who can infect the most vulnerable population of neonates and infants. The most frequent misconception about the disease is that protection provided by childhood immunization is life long. In fact, adolescents become susceptible to whooping cough approximately 6 to 10 years after childhood vaccination. A novel non-invasive whooping cough vaccine has been developed by immobilization of Pertussis Toxin (PT) in electrospun polymer (Polyvinylpyrrolidone, PVP) nanofibers. Our in vitro experiments utilized a sensitive assay for PT based on Chinese Hamster Ovary (CHO) cells to examine the bioavailability of PT in novel electrospun coatings. Under standard culture conditions CHO cells form an attached monolayer. In the presence of intact PT, CHO cells lose contact inhibition and undergo characteristic clumping. We qualitatively measured clumping of CHO cells in the presence of native PT, PT-PVP electrospinning solution, and in dissolved PT-PVP electrospun coating. Microscopic observation showed clumping of cells with sensitivity down to 2.5 ng/mL of PT in dissolved electrospun coating at 48 hours. The results of the in vitro assays confirm retention of non-denatured, biologically active Pertussis Toxin in electrospun nanofibers. The superior surface area to volume ratios of non woven electrospun mats provide an improved platform for the development of a non invasive whooping cough vaccine.

Tejas Gawade, Department of Biology, Stony Brook University, Stony Brook, NY 11794. In Vitro Cellular and Developmental Biology, 43:S31, 2007


2007 JOHN S. SONG AWARD

Taniya Dhillon

Evaluation of Viral Suppressors of Silencing to Stabilize Transgene Expression

Gene expression is a highly regulated and complex process in eukaryotes. Over-expression of a transgene does not always result in an increase in protein levels, but may cause transcriptional or post-transcriptional gene silencing (RNA silencing). Plants use RNA silencing to suppress virus replication and spread in the plant. As a counter measure, some virus genes encode proteins that suppress the silencing mechanism of the plant. We evaluated six such viral suppressors of silencing for their ability to stabilize transgene expression. Various combinations of the green fluorescent protein (gfp) gene and silencing suppressors were introduced into lima bean (Phaseolus lunatus L.) cotyledons using particle bombardment. Post-introduction, GFP expression in the cotyledons was tracked over time with an automated image collection and analysis system. In this transient expression assay, we found that the silencing suppressors, HCPro and p19 stabilized GFP expression as 3? gfp transcriptional fusions; p21 and gamma b stabilized GFP expression when co-introduced independently on separate plasmids from the gfp gene; however, AL2 and replicase did not show any stabilization of GFP expression. The 3? gfp fusions of HCPro and p19 were bombarded into soybean (Glycine max (L.) Merrill) embryogenic tissue. Introduction of the gfp gene without any suppressor was used as a control. Variable GFP expression was observed in all stably transformed soybean clones. An abnormal downward-leaf-curling phenotype was observed in one p19 transgenic plant, suggesting that the p19 suppressor may not only affect the expression of the gene it is fused with, but also other genes in-trans.

Taniya Dhillon, Department of Horticulture and Crop Science, OARDC/The Ohio State University, OH 44691. In Vitro Cellular and Developmental Biology, 43:S24, 2007