Honors Projects Copyright (c) 2013 Illinois Wesleyan University All rights reserved. http://digitalcommons.iwu.edu/bio_honproj Recent documents in Honors Projects en-us Thu, 14 Mar 2013 17:05:34 PDT 3600 Comparison of regional eggshell porosity between the brood parasitic Brown-headed Cowbird (Molothrus ater) and its hosts: the Dickcissel (Spiza americana), and two non-parasitic relatives, the Red-winged Blackbird (Agelaius phoeniceus) and the Common Grackle (Quiscalus quiscula). http://digitalcommons.iwu.edu/bio_honproj/50 http://digitalcommons.iwu.edu/bio_honproj/50 Wed, 18 Apr 2012 07:17:04 PDT The Brown-headed Cowbird (Molothrus ater) is a generalist brood parasite that lays eggs in the nests of many host species, including the Dickcissel (Spiza americana) and two non-parasitic relatives: the Red-winged Blackbird (Agelaius phoeniceus) and the Common Grackle (Quiscalus quiscula). Cowbird eggs reportedly hatch sooner than equivalently-sized host eggs, presumably via accelerated embryonic development enabled by a greater eggshell porosity and consequently greater gas exchange. However, the distribution of pores among apical, equatorial and basal eggshell regions within cowbirds and host species is undetermined. I tested the hypothesis that equatorial porosity would be greatest because respiratory gases primarily cross the eggshell pores and enter or exit the embryo’s circulatory system via the chorioallantoic membrane located in that region. I found that the equatorial region of eggs within species had significantly greater pore density, pore area, and porosity than the basal or apical regions of eggshells from cowbirds (P ≤ 0.006), Red-winged Blackbirds (P ≤ 0.002), and Dickcissels (P ≤ 0.005). Grackle eggshells did not follow this regional pattern, and porosity characteristics did not differ significantly between the equator and base (P > 0.05). Notably, cowbird eggshells had significantly greater pore area and porosity in equatorial regions compared to its three hosts (P ≤ 0.012). Cowbird eggshells had a greater apical pore area than that of the Dickcissel (P < 0.001) and grackle (P = 0.003), and did not have significantly greater eggshell basal pore area or porosity compared to either of its relatives. These observations demonstrate region-specific rather than global increases in eggshell porosity, which may further explain the accelerated embryonic development of cowbirds compared to host species.

]]> Brittany Childs A new species of frog (Strabomantidae: Pristimantis) from Peru with comments on its ectoparasites (Acari: Trombiculidae) http://digitalcommons.iwu.edu/bio_honproj/49 http://digitalcommons.iwu.edu/bio_honproj/49 Tue, 17 Apr 2012 09:28:42 PDT In South America, frogs of the genus Pristimantis are diverse and can be found from lowland forests to elevations of about 4000 m in the Andes. The 444 known species of Pristimantis belong to 16 species groups. One of these groups is the Pristimantis orestes Group, the 14 members of which inhabit the páramo, puna, and upper montane forests in southern Ecuador (3 species) and Peru (11 species). Species of the Pristimantis orestes Group are characterized by having snout-vent lengths ranging from 18.0 to 29.4 mm, short robust bodies, relatively short snouts, narrow digital discs, and areolate ventral skin. Some species have variously colored pale spots in the groin. Herein, I describe a new, diminutive species of Pristimantis from the Andes of northern Peru that I assign to the Pristimantis orestes Group. The new species, denoted Prsitimantis sp. 1, has a snout-vent length of 17.35–29.08 mm (n = 47) in adult females, and 14.39–22.97 mm (n = 40) in adult males, and it differs from all other members of the Pristimantis orestes Group in having prominent scapular tubercles. Ectoparasitic mites (Trombiculidae) of the new species were studied to determine any relation between the degree of infestations and body regions, size, sex, and age. No relationships were found among sexes or ages of frogs. Larger females were 3.85 times more likely to be infested than small females, but no difference was seen between different sized males. The throat had significantly more mites than other body regions and the legs had significantly fewer mites than other regions. Mites were examined using scanning electron microscopy and their morphology was compared to drawings of a previously described mite. The mite on Pristimantis sp. 1 was not Hannimania sp., the genus commonly reported to infest frogs.

]]> Alan W. Brus Determining the Composition of the Dwelling Tubes of Antarctic Pterobranchs http://digitalcommons.iwu.edu/bio_honproj/48 http://digitalcommons.iwu.edu/bio_honproj/48 Fri, 22 Apr 2011 14:46:23 PDT Pterobranchs are a group of marine invertebrates within the Hemichordata, which share characteristics with both chordates and echinoderms. Pterobranchs live in colonies of secreted tubes, coenicia, which are composed of a gelatinous material of unknown composition. Visually, the tubes appear similar to the tunic of tunicates, a group of invertebrates within the Chordata. The nonproteinaceous tunic of tunicates is composed of cellulose, which is unusual. The goal of this study was to determine the composition of the pterobranch coenicium. Some aspects of pterobranch phylogeny are still unclear even after multiple molecular and morphological studies. Identification of any new shared characteristics with either echinoderms or chordates would be valuable in determining clearer relationships among these taxa. Purification methods, histology, and microscopy techniques were used to study the structure and properties of the tube material. To date, the results indicate that that the tube material may be protein but the composition is unknown.

]]> Lukasz J. Sewera Nucleic acids and protein synthesis http://digitalcommons.iwu.edu/bio_honproj/47 http://digitalcommons.iwu.edu/bio_honproj/47 Wed, 17 Mar 2010 09:04:51 PDT The unprecedented growth of interest in protein synthesis among biochemists is both a result of, and has contributed to, our rapidly advancing knowledge of the chemistry and metabolism of the nucleic acids. Over the past two decades, evidence has accumulated which points to an intimate association between cellular nucleic acid and protein synthetic activity. A large number of experiments in bacterial systems have shown that ribonuclease disrupts the cell's protein synthetic machinery and that ribonucleic acid (RNA) can frequently restore it. Studies of bacterial transformation (Hotchkiss, 1957) and the discovery of the autonomous infectivity of tobacco mosaic virus RNA (Gierer and Schramm, 1956) unequivocally established that nucleic acids alone contain the necessary information in their structure to direct the synthesis of new and genetically significant proteins. A large body of information on the fate of C14-amino acids in whole animal demonstrates conclusively that the initial and major site of incorporation of amino acids into protein are the cellular ribonecleoprotein particles (ribosomes). Thus it was clear, before cell-free systems has received much scrutiny, that nucleic acids had some intimate directive role in converting amino acids to protein and that the study of protein synthesis was inseparable from a study of the nucleic acids.

]]> Sheldon Nicol Myology of the Pectoral, Branchial, and Jaw Regions of the Ratfish Hydrolagus Colliei (Holocephali) http://digitalcommons.iwu.edu/bio_honproj/46 http://digitalcommons.iwu.edu/bio_honproj/46 Thu, 04 Mar 2010 14:44:06 PST The musculature of the jaw, branchial, and shoulder regions of the ratfish, Hydrolagus colliei, was dissected and described in an effort to determine possible homologous characters shared by the shark, a member of the subclass Elasmobranchii, and the ratfish, a member of the subclass Holocephali. The musculature of the ratfish jaw differs from the morphological pattern found in sharks in that the jaw muscles of the ratfish are located anterior to the orbit, unlike the jaw muscles of sharks, which are posterior to the orbit. It is suggested that this anterior musculature is a character that was shared by fossil ptyctodonts (Class Placodermi) and is not found in any other living fish today. It is further suggested that the labial cartilages of the ratfish may be remnants of the palatoquatrate cartilage which were excluded as the jaw became fused to the braincase. The morphology of the head of the ratfish best supports the hypothesis that ratfish and ptyctodonts are more closely related to each other than either taxon is to sharks or other jawed fishes.

]]> Dominique Didier '87 The Anatomy of the Hyoid Region of Molossus Molossus and its Implication in Systematics http://digitalcommons.iwu.edu/bio_honproj/43 http://digitalcommons.iwu.edu/bio_honproj/43 Tue, 07 Oct 2008 14:29:45 PDT The hyoid musculature and hyoid apparatus of a bat, Molossus molossus (Chiroptera: Molossidae) are dissected and described. A comparison is made with the hyoid structures of bats of the genera Rhinopoma, Emballonura, Nycteris, Megaderma, Rhinolophus, Pteronotus, Phyllostomus, and Eptesicus, which were previously described by my sponsor Gri'tfiths and associates. In Molossus, the geniohyoid and sternohyoid insertions, as well as the hyoglossus origin, have lifted off the basihyal bone and jointly retain a direct attachment to the basihyal via a small tendon. The hyoglossus is split into three distinct bellies: the most superficial originates from the basihyal raphe, the second originates from the basihyal bone, and the third originates from a very reduced thyrohyal bone. A part of the mylohyoideus has broken away from the main muscle, retaining its insertion on the basihyal--it is termed the mylohyoid profundus. The jugulohyoid muscle is absent, as is the stylohyoideus. The styloglossus muscle is split into two distinct bellies by the hyoglossus muscle. A cladistic analysis of these data gives preliminary support to Koopman's proposal in 1984 for a separation of the superfamilies Emballonuroidea and Rhinolophoidea from the superfamilies Phyllostomoidea and Vespertilionoidea. These data provide the first compelling support for Koopman's taxonomic group Yangochiroptera, comprising the superfamilies Phyllostomoidea and Vespertilionoidea.

]]> Natawadee Prasertphon '91 Toward an Understanding of Alzheimer's Disease: The Effects of B-Amyloid(1-42) and Ibotenic Acid on the Retention of a Spatial learning Task in Rats F:ollowing Multiple Injections into the Hippocampus http://digitalcommons.iwu.edu/bio_honproj/42 http://digitalcommons.iwu.edu/bio_honproj/42 Tue, 07 Oct 2008 14:29:43 PDT Neuropathologically, Alzheimer's disease (AD) is characterized by neuritic plaques and neurofibrillary tangles. Evidence has suggested that a protein called B-amyloid (BA) is a major component of the neuritic plaques and may playa role in the neurodegeneration seen in AD. The cellular mechanisms by which BA induces neurotoxicity, however, are still unclear. Recent evidence suggests that the aggregational state of BA may be relevant to its neurotoxicity. Whether portions of the BA protein or the entire sequence produces neurotoxicity in neurons, however, remains a controversy. Still another controversy is whether BA is directly neurotoxic to neurons or whether it increases the vulnerability of neurons. Recent evidence reported by Doman, Kang, McCampbell and Kang, that injections of BA(25-35) with a low dose of ibotenic acid into the hippocampus did disrupt the acquisition of spatial learning in the rat, supports the vulnerability hypothesis. They suggest that the synergistic effect between BA and ibotenic acid may have produced the neurotoxic effect. In light of recent evidence (McCampbell, Peterson and Tinkler, unpublished) that injections of BA(1-42) alone did not disrupt the retention of a spatial learning task, in this study we assessed the increased vulnerability hypothesis by co-injecting fiA(1-42) with a subthreshold dose of ibotenic acid into the hippocampus of male rats. Another problem related to fiA's neurotoxicity may concern the extent of hippocampal damage it produces. Therefore, we assessed the effects of multiple injections of fiA(1-42) and ibotenic acid into the hippocampus of male rats. Although preliminary, the results of this study conclude that coinjections of fiA(1-42) and ibotenic acid do not disrupt the retention of a spatial learning task.

]]> Jason Pequette '94 Comparison of the Effects of Saporin-IgG Injections into the Nucleus Basalis Magnocellularis and Medial Septal Area of Male Rat as Assessed by the Morris Water Maze Task http://digitalcommons.iwu.edu/bio_honproj/41 http://digitalcommons.iwu.edu/bio_honproj/41 Tue, 07 Oct 2008 14:29:42 PDT Alzheimer's disease currently afflicts approximately 4 million people in the United States, with 100,000 new cases being reported each year. As post mortem examination of AD patientsI brains has revealed a significant decrease in the number of cholinergic neurons, one approach we have taken is to look at the correlation between the depletion of certain cholinergic markers in animals and the resulting behavioral deficits. Two regions of specific interest are the medial septal area (MSA) and the nucleus basalis magnocellularis (NBM). These regions are important because they are the major source of cholinergic neurons in the brain, they are selectively targeted during aging and AD, and there have been many reports of their importance in learning and memory tasks. Therefore in this study we examined the effects on spatial learning, as assessed by the Morris water maze (MWM), in the male rat following intracerebral injections of the selective cholinergic neurotoxin, saporin-IgG. The results of this study indicate that saporin injections into the NBM impaired the performance in the MWM when compared to controls and injections of saporin into the MSA. This was revealed by significantly longer latencies to find a submerged platform and longer latencies during the spatial discrimination test.

]]> Alexander R. V. McCampbell '95 Immunolesions Using Site Specific Injections of 192-lgG Saporin into the Basal Forebrain Fail to Affect Radial Arm Maze Performance in the Male Rat http://digitalcommons.iwu.edu/bio_honproj/40 http://digitalcommons.iwu.edu/bio_honproj/40 Tue, 07 Oct 2008 14:29:41 PDT In this study I investigated the effects of 192-lgG saporin injections into the medial septal area.(MSA) and nucleus basalis magnocel/ularis (NBM) on radial arm maze performance in the male rat. The results of the present study reveal that combined injections of 192-lgG saporin into the basal forebrain failed to disrupt RAM performance when compared to vehicle-injected controls. In addition, intraperitoneal injections using a muscarinic receptor blocker, scopolamine, failed to reveal a compensatory response of the cholinergic basal forebrain that may have explained the lack of behavioral effects of 192IgG saporin. Consequently, the results of this study suggest that a selective reduction in cholinergic transmission in the basal forebrain is, by itself, insufficient to account for the functional impairments observed in spatial learning in the rat. These data do not support the use of 192-lgG saporin as a viable approach to the elucidation of the neuropathological mechanisms that are associated with the cognitive deficits seen in Alzheimer's Disease.

]]> Lesley J. Hickman '96 The Effects of Intracerebral Injections of Substance P, and a Substance P Fragment (5-11) into the Medial Preoptic Nucleus on Lordosis Behavior in the Female Rat http://digitalcommons.iwu.edu/bio_honproj/39 http://digitalcommons.iwu.edu/bio_honproj/39 Fri, 26 Sep 2008 11:43:53 PDT In this study either substance P (SP), SP 5-11, an analogue resistant to enzymatic degradation, or acidified saline was injected bilaterally into the medial preoptic nucleus (MPN) of the medial preoptic area (MPOA) in ovariectomized (ovx) estrogen-primed female rats. The lordosis quotient (LQ) and the lordosis intensity scale (LIS) were recorded using a steroid regime that produced a slow increase of sexual receptivity. In experiment 1, when receptivity was low, bilateral injections of 2 different doses of SP (100 ng,1000 ng/ cannula), had no effect on lordosis behavior when compared to those injected with acidified saline. In experiment , however, when receptivity was maximal, SP 5-11 (1000 ng/cannula) produced a marked decrease in lordosis responding. The results indicate t.hat the effects of bilateral injections of SP on lordosis behavior is dependent on the level of sexual receptivity, and therefore, estrogen levels.

]]> Kellie S. Jones '90 Organochlorine Pesticide Contamination and its Potential Effects on Eggshell Characteristics of Dickcissels (Spiza americana) http://digitalcommons.iwu.edu/bio_honproj/38 http://digitalcommons.iwu.edu/bio_honproj/38 Fri, 26 Sep 2008 11:29:15 PDT Dickcissels (Spiza americana) are small, sparrow-like songbirds that nest in grasslands in the U.S. and winter in Venezuela. Fanners in Venezuela intentionally spray dickcissel flocks with organochlorine (DC) and other illegal pesticides in an attempt to kill them when they feed in both rice and sorghum fields. Previous studies have shown that organochlorine (DC) pesticide' contaminants (e.g., DDT) have significantly reduced eggshell thickness in eagles and falcons.. Although DDT was banned in the United States more than twenty years ago, DC compounds and their metabolites still persist in wildlife, possibly resulting in reduced reproductive success and in disrupted endocrine systems (Harper et al. 1996). Recent studies (e.g., Harper et al. 1996; Klemens et al. 2000; Bartuszegvige et al. 2002) have shown DC contamination in Neotropica1 migratory passerines (i.e., songbirds that breed in Canada and the United States and winter in Mexico and Central and South America.), including dickcissels. The purpose of this study is to determine the relationships between DC contamination on thickness and color (hue, saturation and brightness) of dickcissel eggshells. The ecological implications of contamination may include the effect of eggshell coloration on the amount of male parental investment, reduced hatching success of dickcissel eggs, as well as the success of dickcissels in rejecting brownheaded cowbird (Molothrus ater) eggs.

]]> Bridget Wall '08 Larval Settlement of Ilyanassa obsoleta (Gastropoda) and Capitella sp. I (Polychaeta): Responses to Sediment Cues and Effects of No. 6 Fuel Oil http://digitalcommons.iwu.edu/bio_honproj/37 http://digitalcommons.iwu.edu/bio_honproj/37 Fri, 26 Sep 2008 11:29:14 PDT Metamorphosis in response to bottom sediment was measured in two species of marine planktonic larvae. Ilyanassa obsoleta, a common mud-snail, and Capitella sp. I, a polychaete worm. A sediment control consisted of organic-rich sediment collected from Barnstable Harbor, Ma. One sediment treatment, termed muffled sediment, consisted of the sediment control heated at a high temperature in a muffle oven to remove all organic matter. A sharp decrease in percent metamorphosis was observed in larvae exposed to the muffled sediment condition compared to the sediment control. Results confirmed that settlement involves more than physical contact with the sediment and suggest that the metamorphosis-stimulating factor is probably a water soluble substance. The June 10, 1990, spilI of 7,500 gallons of No.6 fuel oil into Buzzards Bay, Massachusetts, provided oil contaminated samples of salt marsh sediment. Both the sediment control and muffled sediment were contaminated with the oil. The influence of oiled conditions on percent larval metamorphosis varied between species. Ilyanassa obsoleta showed no significant change (ANOVA ~=0.01) in percent metamorphosis between the oiled and unoiled conditions. In Capitel la sp. I, larval settlement rates on oiled sediment conditions were significantly lower than the control sediment. This trend suggests that the oil somehow altered the metamorphosis cue detected by larvae of Capitel la sp. I. However, the variability in results of both species support the need for further studies investigating the specific mechanisms of metamorphosis as wel 1 as the impacts of No.6 fuel oil on the development of marine invertebrate larvae.

]]> Dianne Rudy '90 Effect of Copulation and Copulation Time on Female Reproductive Development in Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae) http://digitalcommons.iwu.edu/bio_honproj/36 http://digitalcommons.iwu.edu/bio_honproj/36 Fri, 26 Sep 2008 11:29:11 PDT It has been established that a prolonged copulatory period of 3-4 hours is necessary for maximal insemination to occur in the western corn rootworn (WCR). This complete mating period has been suggested to speed ovarian development. The purpose of this study was to determine the relationship between copulation and ovarian development in the WCR. Using 11 and 12 day postemergence virgin WCR beetles, four female groups of varying copulatory duration were established: (1) 15 min. in copula (2) 1 hr. in copula (3) 2 hrs. in copula (4) a control group mated until natural completion. After copulation, these beetles along with a control group of unmated females were placed in isolated cage vials. Frequency of egg-laying and post-copulation change in female weight was recorded up until the time of dissection. The beetles were then sacrificed between 21-24 days post-copulation and the effects on ovarian development were evaluated with the following criteria: (1) reproductive status (an ovarian rating system) (2) morphometric analysis of ovarian area (using an Olympus C-R Research Image Analyzer with an IBM/PC Microcomputer). The presence of spermatozoa in the spermatheca was also noted at the time of dissection. The results demonstrate significantly larger mean ovarian area and greater mean reproductive status rating (P<0.05) in the control group of mated until completion females compared with the control group of unmated females. Egg-laying frequency and mean post-copulation change in weight reflected fully developed ovaries present in the mated until completion beetles and not in the unmated beetles. The results with the groups of varying copulatory duration suggest that spermatozoa may play a role in the development of fully maturated ovaries. In addition, it appears that directly after copulation some factor other than spermatozoa is responsible for significant increases in reproductive development. This other factor appears relatively transient and does not maintain a significantly developed reproductive state past approximately 14 days post-copulation.

]]> David Sherwood '90 Systematic Relationships of Rhinolophid Bats: Based on Hyoid Morphology http://digitalcommons.iwu.edu/bio_honproj/35 http://digitalcommons.iwu.edu/bio_honproj/35 Fri, 26 Sep 2008 11:29:10 PDT The hyoid regions of three species of bats within the family Rhinolophidae were dissected and compared with similar data of the hyoid region of other families obtained from Griffiths (personal communication). A cladistic analysis was performed using these data to analyze inter-generic relationships within the Rhinolophidae and inter-familial relationships between the families Rhinolophidae, Megadermatidae, Nycteridae, Rhinopomatidae and Emballonuridae. Two possible inter-generic cladograms are most parsimonious. Within the rhinolophids, either Hipposideros diadema or Hipposideros armiger is the most distantly related species depending on which of two characters, loss of the sphincter colli or loss of the omohyoid, has undergone convergent evolution. Both cladograms show a close association between Triaenops persicus and Rhinonycteris aurantius. At the inter-familial level, two most parsimonious cladograms were produced. Emballonurids, nycterids and rhinopomatids are closely united in both cladograms. A question of which of two characters, sternothyroid shift of origin or omohyoid shift of origin, has undergone convergent evolution leaves the relationship between rhinolophids and megadermatids unclear.

]]> Andrea L. Smith '90 Intracerebral Injections of Substance P Fragments (5-11) and (1-7) into the Dorsal Midbrain Central Gray Have No Effects on Lordosis Behavior in the Female Rat http://digitalcommons.iwu.edu/bio_honproj/34 http://digitalcommons.iwu.edu/bio_honproj/34 Fri, 26 Sep 2008 11:29:08 PDT Substance P (sP), a neuroactive peptide, has now been implicated in a wide range of behaviors. One in particular is female rat sexual behavior. Recently, it has been shown that bilateral injections of sP into the dorsal midbrain central gray (dMCG) of estrogen-primed female rats facilitate sexual behavior (lordosis). Uncertainty remains, however, concerning the mode of action of synaptically released sP. Indeed, most of our understanding of sP activity has revealed that its full structural sequence is not needed for biological activity. This has led to speculation that sP may be processed into one or more types of fragments before it can exert its behavioral effect. In view of these unusual properties, we must first develop a thorough understanding of the effects of sP fragments before we can fully appreciate the significance of this peptide on the expression of female sexual behavior. In a series of behavioral experiments, we assessed the effects of injecting two different fragments (sP 1-7 and sP 5-11) into the dMCG of ovariectomized, steroid primed, female rats. In the first experiment, sexual receptivity was measured following injection of sP(1-7), (5-11) or acidified saline directly into the dMCG of maximally receptive (estrogen and progesterone primed) females. At five and thirty minutes post injection, an assessment revealed that neither sP(5-11) nor (1-7) had an effect on sexual behavior when compared to saline injections (controls). 1n the second experiment, speS-II) or acidified saline were injected into the dMCG of estrogen primed female rats showing a minimal lordosis response, and the effects of speS-II) injections were compared to those of controls (saline). Again, no significant difference in sexual behavior was observed following injection of speS-II) or saline. In conclusion, our data suggest that the effect of sP on lordosis behavior following injection into the dMCG is not due to the activity of biologically active fragments.

]]> Jodi K. Block '91 Cystic Fibrosis: Cluster Analysis of Microbiology and Pulmonary Function http://digitalcommons.iwu.edu/bio_honproj/33 http://digitalcommons.iwu.edu/bio_honproj/33 Fri, 26 Sep 2008 11:29:06 PDT In an attempt to find a relationship between pulmonary infection and pulmonary function in cystic fibrosis (CF) patients, microbiology data and pulmonary function test (PFT) data for clinic patients' visits were obtained from the University of Minnesota Relational Database. The two files were merged, totaling 12,193 cases, and then analyzed using a quick cluster subroutine of SPSSX on the University of Illinois IBM Mainframe System. QUICK CLUSTER analysis showed a relationship between the virulence of the microorganisms, the amount of growth of the microorganisms, and the pulmonary function test scores of CF patients

]]> Lori Lee M. Larson '91 Regulation of Methyl Farnesoate Production by the Lobster Mandibular Organ in vitro http://digitalcommons.iwu.edu/bio_honproj/32 http://digitalcommons.iwu.edu/bio_honproj/32 Fri, 26 Sep 2008 11:29:05 PDT Methyl farnesoate (MF) is a crustacean compound that is structurally similar to juvenile hormone, a substance that regulates insect growth and reproduction. This similarity has led to the suggestion that MF may have juvenile hormone-like effects in crustaceans. If this is so, regulation of MF levels might be an important mechanism in the control of crustacean molting and reproduction. The understanding of, and ability to manipulate, the regulation of MF production could be a powerful tool in the aquaculture of economically Important crustaceans.

In the lobster Homarus americanus, MF synthesis occurs in the mandibular organ (MO). In vivo studies have shown that MF synthesis is negatively regulated by the sinus gland (SG), a structure located in the crustacean eyestalk end known to produce neuropeptides. To determine the effect of SG peptides on MF synthesis, fragments of MO tissue were incubated in culture medium supplemented with radiolabeled methionine (a precursor of MF). I used this in vitro bioassay to compare the activity of a crude SG extract with that of two peptides purified from the extract. The crude SG extract produced a substantial decrease in MF synthesis by MO fragments when compared with controls. One of the purified peptides also inhibited MF synthesis, but the other had no effect. The data suggest that the first peptide is the MOIH (mandibular organ inhibiting hormone) for the lobster. However, its inhibitory effect on MF production is not as complete as that of the crude SG extract, suggesting that this peptide may act synergistically with another compound from the SG to produce full inhibition.

]]> Amy Shaub '97 The Effect of Temperature on the Growth of the Zebra Mussel, Dreissena Polymorpha (Pallas) http://digitalcommons.iwu.edu/bio_honproj/31 http://digitalcommons.iwu.edu/bio_honproj/31 Fri, 26 Sep 2008 11:29:03 PDT Dreissena polymorpha (Pallas), zebra mussels, are recent invaders of North American freshwater systems. They have a high reproductive rate and settle in high densities which can clog water intake valves and pipes. Many studies investigating the use of heat as a control measure have examined the effects of high temperatures on zebra mussel mortality. Much less is known about the effect of temperature on the actual growth rate and development of zebra mussels. This study examined the growth rates of zebra mussels at 10°C, 20°C, and 25°C over two four-week periods in the laboratory. Mussels were placed in culture dishes (five similarly sized mussels per dish) and fed 100 ml of the algae Chlorella pyrenoidosa (Chick) daily at a concentration of 4.13 * 105 cells/mI. Shell length and shell height measurements were taken three times during the experiment. Although shell length is the measurement typically used in growth studies, it has not been documented whether increases in shell length are accurate indicators of increases in tissue weight. This study compared both shell length and shell height with tissue weight. Since the correlation between shell length and tissue weight (r^2 = 0.811) was slightly higher than that between shell height and tissue weight (r^2 = 0.723), shell length was used as the growth indicator in this study. Growth was significantly greater at 25°C than at either 10°C or 20°C during one two-week period (Scheffe's, p < O.O5). Mortality was also significantly greater at 25°C than at 10°C. The results from this study are important because factors which reduce growth should decrease the long-term success of the zebra mussels and therefore should be useful as possible control methods. Also, scientists working with zebra mussels in the laboratory will find the results of this study useful in determining the best conditions in which to raise zebra mussels.

]]> Tamara K. Ross '93 The Effects of Bilateral Injections of Neuropeptide K into the Medial Preoptic Area on Male Rat Copulatory Behavior http://digitalcommons.iwu.edu/bio_honproj/30 http://digitalcommons.iwu.edu/bio_honproj/30 Fri, 26 Sep 2008 11:29:01 PDT The first mammalian neuropeptide to be characterized was substance P (sP) , and it is now recognized that sP is a member of a structurally related family of peptides, the tachykinins. Extensive studies have demonstrated. that sP and some related tachykinin peptides play key roles as neurotransmitters and neuromodulators. The synthesis of different members of the tachykinin family is in part due to the modifications' of three sP-encoding preprotachykinin (PPT) mRNA's that are derived from a single sP gene. At least four tachykinin peptides can be synthesized as a result of these differential modifications including sP, neurokinin A, neuropeptide and neuropeptide K (NPK). Whereas the behavioral significance of sP has been extensively studied, there has been very little examination of the behavioral significance of NPK. This is especially true of the examination of male reproductive behavior. Dornan and Malsbury (1) reported that bilateral injections of sP into the media~ preoptic area (MPOA) facilitated male rat sexual behavior. High concentrations of PPT mRNA's are found within the MPOA, and as previously mentioned, NPK is derived from PPT mRNA's. At present, however, it is not known whether NPK plays a role in the neural regulation of male copulatory behavior. In the following experiment, we examined the role of NPK within the MPOA in the regulation of male rat copulatory behavior.Sexually experienced adult male Long-Evans rats were used. Chronic cannulae implants were stereotaxically placed 2mm above the MPOA, and following 7-12 days of recovery, the animals were behaviorally tested to obtain a baseline measure of copulatory behavior. One week following baseline testing, the animals were randomly placed into 4 groups and were bilaterally injected with .5ml solutions of either saline, 100ng NPK, 1000ng NPK or 2000ng NPK and the effects of these injections on copulatory behavior were determined. Following testing, brains were histologically analyzed to confirm the placements of the cannulae. Analysis revealed that bilateral injections of 1000ng NPK into the MPOA produced an abolishment of copulation in a significant number of animals, whereas injections of 100 and 2000ng NPK produced no significant effect on the copulatory behavior. It was noted thatinjections of2000ng NPK producedan abolishment ofcopulation in50 % of the animals, but due to the small number of animals in the group (n = 4), the result was not significant. Although the complete role of the tachykinins in the regulation of copulatory behavior has yet to be elucidated, it seems that sP and NPK, two tachykinins synthesized from the sP gene, exert opposite effects in the regulation of male copulatory behavior.

]]> Peter Malen '91 A Morphological and Chemical Study of the Lichen Genus Hypogymnia in North America North of Mexico http://digitalcommons.iwu.edu/bio_honproj/29 http://digitalcommons.iwu.edu/bio_honproj/29 Fri, 26 Sep 2008 11:28:58 PDT The lichen genus Hypogymnia is widely distributed throughout the world, in such places as Europe, Asia, Africa, Australia, New Zealand, Japan, and North America. Currently, there are twenty-one recognized species of Hypogymnia in North America, but no comprehensive study of the genus in North America has been published. My study of the genus Hypogymnia was performed on a sample of 784 North American specimens collected from the western United States, southern Canada, the Great Lakes region, and the eastern United States. The morphological characteristics of each lichen specimen were examined. Chemical studies included preliminary spot test screening of the cortex and medulla of each lichen specimen, followed by thin layer chromatographic procedures to attempt to identify the lichen substances present in each specimen, and to evaluate the chemical variation within each species. In this preliminary study of the genus Hypogymnia in North America, specimens of fifteen of the twenty-one described species of Hypogymnia have been examined as well as specimens of four new, undescribed species tentatively recognized by Lawrence Pike (on loan from the u.s. National Herbarium at the Smithsonian Institution). Patterns of morphological variation and chemical variation were identified for each species. New chemical strains have been detected in Hypogymnia imshaugii. My examination of Pike's undescribed, new species leads me to support the recognition of three of the four species as valid species worthy of publication. Thus, I recognize a total of 24 species of Hypogymnia in North America north of Mexico. The first comprehensive key to all of these species of Hypogymnia has been prepared. Additionally a brief description of the morphology, chemistry and geographical distribution of each species is provided.

]]> Melinda McFarlin '91