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PARTICIPANTS and PROJECTS 1998

Miriam Blum To determine if ethanol changes crayfish behavior, Procambarus clarkii subjects were submerged in 7% ethanol for a period of 90 minutes, and then isolated in separate storage containers. For the next ten days following the ethanol treatment the experimental subjects were paired and placed in holding tanks for observation of social interactions. Data were collected in all social interaction periods starting 24 hours after the ethanol treatment. All animals were housed individually before and between social interactions. For each social interaction, a pair of ethanol treated subjects (n=20) were placed on opposite sides of a divided common tank with the divider in place for a 5 minute introductory period. No data were recorded during this period. After 5 minutes, the divider was removed and the subjects were allowed to interact for a 10-minute period. Only the data collected in the first five minutes of the paired interaction were analyzed to determine behavioral differences. Controls were established by repeating this procedure with subjects not exposed to ethanol (n=19). While monitoring the social interaction periods, data were collected on the basis of observed aggressive or submissive behaviors of the test subjects. Aggressive behaviors included dominant stance, aggressive chasing, approaching and aggressive clawing. Submissive behaviors included tail flips, defensive chasing, defensive clawing, and retreating. Analysis of the data indicates a significant behavioral difference (p<0.05) in the frequency of approaching behavior between the experimental and control groups. The results indicate that the control group had a significantly higher frequency of approaching behavior.

Brooke Byerley The effects of autogamous and heterospecific pollinations on female reproductive success were determined for sympatric populations of Phlox cuspidata and Phlox drummondii. Percent fruit set and percent seed set were used as markers of success. Differences in mean values of fruit set were found to be dependent on the recipient species and the type of cross performed. Differences in seed set were found within each species and within autogamous pollinations as opposed to being the product of interaction among the two as with fruit set. Effects of a mixed-donor pollen load consisting of autogamous and heterospecific pollen are under present investigation. It is suspected that the overall rates of fruit set will be somewhat diminished because of an increase in microgametophytic competition within the style. No change in mean seed set is predicted.

Joseph Cordova Gene flow is the movement of genes within or among populations. Important consequences of gene flow are the avoidance of detrimental effects caused by inbreeding and allowance for the selection of favorable traits among a species. Limiting gene dispersal can result in genetic drift among small populations which results in a higher inbreeding percentage. Gene flow and overall seed success rates increase with the receiving of pollen from a non-related plant, but at the same time gathering genes from distant donors can leave the plant less fit to live in the surrounding environment. Therefore it appears as if a medium exists in which desired genes from donor plants can be obtained. With pollinator dependent species, gene flow distances are determined by the pollinator. As a result, an overlap between optimal donor distances and actual pollinator distances can result. The optimal intermediate for populations of Phlox drummondii is between 1 and 10 m, and pollinators on average work within a range of 2.5 m. In this experiment, the effects of plant distance on gene flow and related genetic effects is studied in populations of Phlox drummondii. This is done using a dominant Twinkle phenotype in the middle of a population with the neighboring recessive wild type phlox at varying distances. It is hypothesized that gene flow will decrease both as distances between populations increases and as the number of plants between the donor and recipient increases.

Jennifer Fite This study was performed to determine the optimum nutritional conditions for sporagiospore sporulation in Mucor rouxii. Sporulation seems to be dependent on nutritional conditions, yet the conditions that yield maximum sporulation have not been determined in this organism. If sporulation is a mechanism for the organism's survival, one could hypothesize that nutritional depravation would result in increased sporulation. To determine the maximum sporulation conditions, the organism was grown on tomato juice agar plates. Researchers have typically used a 50% tomato juice mixture. Higher and lower concentrations of tomato juice were used to grow the organism. A supplemented Yeast Extract Peptone (YEP) medium and four different fruit juices were used as well to determine the extent of sporulation with different nutritional sources. Replicates (six) were done for each test condition to determine the standard error for each trial. The spores from each trial were harvested and manually counted using a hemocytometer, and the spore counts were compared to a standard curve (a curve in which absorbance at 600 nm was plotted as a function of the number of spores per ml). This allowed the spore concentration of each plate to be determined spectrophotometrically by determined absorance at 600 nm. The results indicated that a 50% tomato juice agar yielded the maximum amount of sporulation. The lower concentrations yielded less growth and lower sporulation of the fungal colonies. The four fruit juices yielded less growth as well. Famine conditions did not increase sporulation. Hence, the results do not support the hypothesis. Sporulation obviously ensures the fungus survival, but nutritional depravation does not seem to trigger this process.

Rebeccaa Grieser In this study, two paths on the versatile life cycle of Mucor rouxii were documented. These two paths, arthrosporulation and fragmentation by septation were examined in several different culture media conditions. In addition, data were collected and analyzed to determine the culture media conditions resulting in the maximal level of arthrosporulation and fragmentation. Both fermentable and non-fermentable carbon sources were tested, including yeast extract peptone (YEP), YEP plus glucose, YEP plus acetate, YEP plus glycerol, YEP plus pyruvic acid, YEP plus citric acid, and YEP plus glutaric acid. The pH of the media was adjusted to 6.5. All cultures were inoculated with 105 spores per ml and incubated in air bath shaker at 200 rpm and 28 C for 32 h. The cultures were then harvested, blended, and filtered, to separate and subsequently concentrate the arthrospores and fragments. Results support the hypothesis that arthrosporulation would occur maximally in a fermentable carbon source. Arthrosporulation was seen maximally in culture media with a high percentage of glucose. There was no previous data on fragmentation. It was seen maximally in culture media with a lower concentration of glucose.

Katie Hutka Superparasitism has become a controversial issue in ecological studies. It initially seemed maladaptive, but now its benefits and the factors that influence it are being examined. I studied the effect of host to parasitoid ratio manipulation on the incidence of self and conspecific superparasitism using the solitary parasitoid Xanthopimpla stemmator. The ratios were manipulated in Experiment 1 so that the parasitoid to host ratios were: 1:0.25, 1:0.5, 1:1, 1:2 (Table 1 for set up). In Experiment 2, the ratios were: 1:0.5, 1:1, 1:2, 1:4. I exposed the host to the wasps for three hours, then I removed and dissected the hosts in order to search for wasp eggs. The first experiment showed that the number of eggs laid per trial did not significantly change with increasing host number (ANOVA, p>0.05). However, the average number of eggs per pupa did decline with increasing number of pupa (ANOVA, p<0.01). I also found that the lowest frequency of superparasitism (both self and conspecific) occurred in the 4 wasp : 8 pupa set-up. The pattern of parasitism with 4 wasp : 4 pupa differed from a Poisson random distribution (Chi Square test, p<0.001). The pattern of parasitism with 4 wasp : 8 pupa also differed from a Poisson random distribution (Chi Square test, p<0.001). Data are still being collected for the second experiment.

Callie McCormack A flower's floral formula denotes the kind and number of organs that make up the flower. Though it is relatively constant, especially in taxa with fewer numbers of organs, some species are found to have higher degrees of variation among these parts than others. In the Polemoniaceae family most species have a floral formula of 5-5-5-3. This denotes a floral formula consisting of 5 sepals, 5 petals, 5 stamens, and a tricarpellate gynoecium with 3 stigmatic lobes (Lehman). Meristic variation seen in certain flower parts of Phlox drummondii may be linked to instability in other parts (i.e. flowers with uncharacteristically high numbers of sepals are more likely to have a greater number of petals). In this study a survey was conducted using a population of the Twinkle cultivar of Phlox drummondii to determine the degree of meristic variation for the cultivar. Data from the study suggests that flowers demonstrating meristic variation in number of stigmatic lobes will also show variation in the number of ovules they produce. More specifically, it is proposed that there is a direct correlation between these two parts(i.e. a flower with 3 stigmatic lobes will produce 3 ovules where as one with 4 stigmatic lobes will produce 4 ovules). This would mean that plants with a preponderance of flowers with 4 stigmatic lobes would be selectively favored due to higher production of ovules and thus higher production of seeds. Many researchers have studied meristic instability by quantifying the degree of variation and determining what factors cause the variation. The research conducted in this study focuses on determining what effect, if any, such instability had on fitness. In this study we propose to determine if there is a selective advantage to producing 4 ovules by comparing the reproductive output of 3 vs. 4.

Anthony Pruett In this experiment data was collected and analyzed to determine if intracellular protease activity and production of protease zymogen in Mucor rouxii could be induced by limiting exogenous protein in the growth environment. One liter yeast extract peptone cultures with peptone concentrations from 0.1% to 5.0% were inoculated with 105 M. rouxii spores per mL. Cultures were harvested at 18 hours of growth and extracts subjected to Lowry and azocasien degradation assays to determine protein concentration and protease velocity, respectively. From these data, specific enzyme activity was calculated at 2 hour increments between 0 and 8 hours of extract incubation. Preliminary results supported the hypothesis that decreased availability of exogenous proteins can induce protease zymogen production and induction in M. rouxii.

Jeff Raimondo Heat shock proteins (HSPs) protect all cells from a variety of environmental stresses, including extreme heat, heavy metals, metabolic poisons, etc. HSPs may also play a role in protecting severed axons from degenerative processes. Severed and intact medial giant axons (MGAs) of the crayfish ventral nerve cord (VNC) were monitored for viability using electrophysiological criteria. Data were collected from crayfish MGAs in the following treatment groups: nonsevered VNCs, VNCs with left MGAs that were severed in vivo, for approximately 2 months; VNCs with severed left MGAs that were heat shocked for 2 hours in vitro, and VNCs with severed left MGAs that were treated with an antibody to HSP70 during the heat shock. There was no difference in the resting membrane potentials of intact or severed MGAs, indicating that the severed MGAs survived for 2 months. Similarly, severed and intact MGAs exhibited normal resting membrane potentials after heat shock treatments. There was also no difference in the resting membrane potentials of control MGAs and MGAs treated with the HSP 70 antibody for 2 hours. However, the resting membrane potentials collected from severed MGAs exposed to the HSP 70 antibody and heat shock were depolarized and significantly different from the resting membrane potentials collected from control MGAs. These data indicate that MGAs which are severed from the cell body for approximately 2 months are capable of surviving extreme heat shock exposure, but the survival is not as apparent when the severed MGAs are treated with an HSP 70 antibody during the heat shock treatment.

Jennifer Shanor The purpose of this study was to determine if a difference in fitness exists between the large and small varieties of the female wasp Xanthopimpla stemmator. The fitness of an organism is often indicated by the number of its offspring that survive to successfully reproduce. In these experiments, fitness was measured through egg load and mate choice trials. The egg load portion of the study consisted of exposing each wasp to one pupa everyday for the first 20 days of the wasp's life, and recording the number of eggs laid by each wasp. Mate choice trials consisted of placing a small and large virgin female in a glass jar, and subsequently adding an average-sized male to the same jar. The size of the first female that the male successfully mated with was recorded. I hypothesized that the large female wasps would demonstrate a higher degree of fitness by being chosen as a mate more often and by laying more eggs in the first 20 days of life. Results indicate that large female wasps possess a mating advantage, as average-sized males mated with large females 68% of the time. In regards to egg load, large females began laying eggs at a younger age; they laid more eggs in the first 20 days of life; and they superparasitized more often.

Jessica Stern Xanthopimpla stemmator, an endoparasitoid of lepidopteran stalk borers, uses parasitism as a means for providing protection and nutrition to its offspring. Previous research has hypothesized that X. stemmator can control offspring sex ratios in response to environmental factors, such as host scarcity (King, 1992). Wasps may resort to superparasitism, the deposition of more than one egg in a single host, to increase reproductive success. This superparasitism creates a larval competition within the host pupae. In this study, the effects of larval competition on sex ratios was examined to determine whether skewed sex ratios are due to an advantage of the first egg deposited, later egg deposited, or whether there exists an advantage to sex of the offspring deposited into the pupae. In the first experiment, the order of parasitization was experimentally manipulated by allowing an unmated female to parasitize a single pupa. Upon oviposition, the same pupa was then administered to a mated female for superparasitization (173 trials). The reciprocal experiment, in which a mated female was administered a single pupae for parasitization and an unmated females was given the same pupae for superparasitization was also conducted (174 trials). Statistical results indicate that there is an advantage to the order of parasitization, such that the first egg deposited in the pupae is more likely to emerge successfully that the second egg deposited, G(1)=104.4, p<.0001. However, no differences between the number of successful emergences of a wasp existed between singly and superparasitized pupa. Further experiments are being conducted to determine whether differences in the success of the order of parasitization are a result of the length of interval between parasitization and superparasitization.

Kenny Youens The cellular stress response involves increased production of a family of proteins with varying molecular weights called stress proteins. It is reported to be evoked by exposure of a cell to such stressful stimuli as cellular disruption, acute temperature increase, and ethanol or heavy metal poisoning. Copper (II) chloride was tested as an inducer of the stress response by application of 50 µM and 500 µM copper (II) chloride to the crayfish ventral nerve cord in vitro for two hours. Autoradiography and immunoblotting were used to show that exposure of the crayfish ventral nerve cord to 500 µM copper (II) chloride evokes the production of the full spectrum of inducible stress proteins, while exposure of the crayfish ventral nerve cord to 50µM copper (II) chloride may selectively induce production of the 90 kD stress protein family.

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