<p> The phenomenon of genetic recombination is of fundamental importance to the evolution and adaptation of species, and is a valuable laboratory aid to the biological scientist. Probable mechanisms of control of recombination are largely unknown, due partly to the difficulty of obtaining artificial mutants affecting the process. The studies reported here avoid this difficulty by the use of different factors controlling recombination which occur naturally in the species Neurospora crassa and N. sitophila. Studies of hybrid N. crassa strains carrying factors from N. sitophila are described, and some models for the control of genetic recombination are discussed. </p> / Thesis / Master of Science (MSc)

<p> Recently, the discovery that taxol (2), a highly modified diterpenoid available from Taxus species, possesses anticancer activity has attracted considerable interest. The synthesis of [1-3H]-geranylgeranyl pyrophosphate(1b), a labelled form of the precursor to the diterpenoids(1a), and its incubation with a cell-free enzyme preparation from Taxus x media densiformis, a species of yew tree, were investigated.</p> <p> The investigation into the biosynthesis of taxol(2) was to be accomplished by monitoring the enzymatic transformations of (1b). The synthesis of 1b was accomplished via a convergent method using geraniol, a ten carbon compound, as the starting material. Essentially two molecules of geraniol were chemically manipulated and condensed to give geranyl geraniol which was oxidized to the corresponding aldehyde and then reduced using sodium borotritide. The radioactive alcohol was subsequently converted to the pyrophosphate (1b) using standard methodology. Cell-free extracts of Taxus x media densiformis were prepared and incubated with [1-3H]-GGPP (1b), the intermediates were extracted, and then analyzed by scintillation counting and radioactive gas chromatography. Identification of these labelled intermediates was attempted in order to provide information about the biosynthesis of 2. (Diagram included in thesis)</p> / Thesis / Master of Science (MSc)

Page 39 was included twice in the thesis. / <p> This thesis describes reactions involving low valent technetium nitrosyl complexes. O-Substituted hydroxylamines were reacted with [TcOCl4]- in methanol producing [Tc(NO)Cl4]-. NMR studies have shown that two species are present besides the starting material during this reaction. One of these species was confirmed by NMR to be the corresponding alcohol of the O-substituted hydroxylamine. The other species is believed to be a hydroxylamine intermediate that is in equilibrium with the final product, [Tc(NO)Cl4]-. A plausible mechanism for this reaction was proposed that included an oxo group attack of the α-carbon of the O-substituted hydroxylamine which would lead to the formation of the corresponding alcohol. In an attempt to confirm the mechanism, O-18 labeled [TcOCl4]- was synthesized, however, there is no conclusive evidence that the label is transferred to the corresponding alcohol at the present time. Substitution reactions of [Tc(NO)Cl4]- with phenanthroline and bipyridyl ligands were also investigated. Reactions with these ligands produced [Tc^(II)(NO)Cl3phen] (4a) and [Tc^(II)(NO)Cl3bipy] (5), respectively. The crystal structures of these complexes showed that the meridonial isomer is produced with one nitrogen atom of the bidentate ligand trans to the nitrosyl moiety. EPR spectra of these compounds confirm the Tc(II) oxidation state of the metal. All of the chloride ligands of 4a and 5 can be displaced using AgBF4 in acetonitrile solvent, which, in the case of bipyridyl, produces [Tc^(I)(NO)(bipy)2(MeCN)]2+ (6). Other technetium nitrosyl containing complexes are formed in these reactions and are currently awaiting x-ray structure determination.</p> / Thesis / Master of Science (MSc)

<p dir="ltr">Blanding’s turtles (<i>Emydoidea blandingii</i>) and Wood Turtles (<i>Glyptemys insculpta</i>) are two threatened species that face various natural and anthropogenic threats to their populations. Many of these threats cause a decline in their recruitment, which can lead to drastic declines in populations. Females put themselves at-risk during periods of movement. My objectives were to identify portions of the season that females were most at-risk, potential nest predators, preferrable nest microhabitat characteristics, and movement of hatchlings. I studied movements in adult females of both species at a site in Northern Michigan using GPS and radiotelemetry. I compared these movements to the relative level of risk, or resistance, in the path they chose to take. I found both species had relatively similar resistance movements over the entire season. It seems that Blanding’s turtles tend to make more resistant movements during nesting, while Wood Turtles seem to be less resistant. Neither species seems to take the least resistance path available. I also conducted nesting surveys to determine nesting locations and selection characteristics at the site for both species. I did not find any characteristic that predicts nesting locations. The located nests were also recorded via trail cams to assess for predator activity. I recorded many species on trail camera review, but I did not note any predation behavior, all damage to nest cages were caused by humans and their vehicles. Lastly, I used radiotelemetry to analyze movements for hatchling turtles. Hatchlings of both species tended to make short daily movements until they reached a wetland. I also found hatchling’s succumbed to predation, desiccation, and road mortality. My data suggests further research needs to be conducted to expand our knowledge on recruitment threats. Nevertheless, I suggest active management for the threats we have noted. Nest cages seemed to be relatively successful at protecting nests, so I recommend continued nest cages to prevent or deter predators. Head-starting may be a strong strategy to help hatchlings reach a larger size before release. These larger hatchlings would also allow for larger transmitters and longer tracking times. This will help to prevent lost turtles and further our knowledge on hatchling success.</p>

京都大学 / 新制・課程博士 / 博士(理学) / 甲第24874号 / 理博第4984号 / 新制||理||1711(附属図書館) / 京都大学大学院理学研究科生物科学専攻 / (主査)教授 朝倉 彰, 教授 森 哲, 准教授 下村 通誉 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

Phytophthora ramorum, an exotic forest pathogen known as ‘sudden oak death’ (SOD), has received considerable attention in recent years because of its effects on vegetation structure, composition, and fire disturbance regimes in western U.S. coastal forests. This research examines differences in the importance (e.g., density, dominance, and frequency) and distribution of five host species of P. ramorum–– Umbellularia californica (California bay laurel), Quercus agrifolia (coast live oak), Pseudotsuga menziesii (Douglas fir), Sequoia sempervirens (Coast redwood), and Arbutus menziesii (Madrone)––in Soquel, California. A stratified random sampling design was used to select 66 plots surrounding a managed forest edge in Soquel Demonstration State Forest. Vegetation measurements were conducted in summer 2013. In each plot, all trees ≥3 cm diameter at breast height (DBH) were identified to species, counted, and DBH, height, and canopy position measured. Leaf area index (LAI) of bay laurel was measured to quantify the amount of leaves available for pathogen dispersal with a LiCOR 2200 Plant Canopy Analyzer. In addition, morning (9:00 am) and afternoon (1:00 pm) photosynthetically active radiation (PAR) were quantified using a quantum light sensor. This paper examines the influence of environmental variables, including distance to edge, aspect, slope, and light availability on host species spatial patterns in Soquel, CA. Studying P. ramorum host pattern and importance among managed forest edges is critical for determining hotspots most susceptible to infection and spread, thus relevant for implementing control measures.

Temperature represents a major driving force in biology as it influences essential functions across multiple levels of biological organization. The role of temperature is especially important for ectothermic animals, whose biotic processes are dependent on both body and environmental temperature. Assessing the relationship between temperature and organismal performance represents an important research direction as temperatures continue to warm under anthropogenic climate change. Chapters two and three are focused on a recently colonized population of the invasive Mediterranean House Geckos at the northern edge of their invasion front. These chapters examine the ecological and physiological factors that enable these lizards to persist in a cooler and more temperate environment than their native range. The thermal breadth of a reptile greatly influences its ability to tolerate a thermally variable environment, particularly when environmental options are limited for behavioral thermoregulation. These chapters explore the thermal performance of this species, and the results show that the eurythermality of these geckos promotes their rapid colonization of novel environments despite experiencing prolonged periods of cool temperatures. Chapters four, five, and six, by contrast, shift focus to larval amphibians to explore the constraints and factors underlying plasticity in acclimation to temperature extremes. As habitats continue to warm with climate change, ectotherms with limited capacity to thermoregulate, such as larval amphibians in shallow ponds, will be under a heightened threat of heat stress and mortality. Resultantly, identifying different factors that can increase organismal heat tolerance would reduce the risk of overheating and promote survival. Chapters four, five, and six explore this topic by measuring the critical thermal maximum (CTmax) of larval wood frogs. Chapter four focuses on the tradeoff between basal CTmax and plasticity of CTmax and its consequences for how a larval anuran responds to an acute heat shock. Chapter five examines the role a viral pathogen, ranavirus, has on larval CTmax. Surprisingly, a lethal dose of ranavirus did not reduce CTmax which goes against the common pattern of pathogenic infections lowering host heat tolerance. Lastly, chapter six explores the relationship between the gut microbiota and host CTmax with a particular focus on cross-species microbiota transplants. In line with our prediction, transplanting the gut microbiota of a heat-tolerant donor species promoted greater CTmax in the heat-sensitive recipient species.

京都大学 / 新制・課程博士 / 博士(農学) / 甲第24243号 / 農博第2522号 / 新制||農||1094(附属図書館) / 学位論文||R4||N5414(農学部図書室) / 京都大学大学院農学研究科応用生物科学専攻 / (主査)教授 松浦 健二, 教授 大門 高明, 教授 日本 典秀 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM

Invasive species are alien to the ecosystem under consideration and cause economic or environmental damage or harm to human health. Two alien insects that fit this description are the brown marmorated stink bug, Halyomorpha halys and the spotted lanternfly, Lycorma delicatula. Both invaders are polyphagous pests that feed on a myriad of plant species and inflict severe crop losses. As sustainable control methods depend on the accurate monitoring of species’ invasion and involve the use of natural enemies, we addressed these two facets by exploring novel monitoring techniques and deciphering host-parasitoid interactions for improved integrated pest management. Thus, we adopted ‘BugMap’, a citizen science initiative that enables students, farmers and everyday citizens to report sightings of H. halys from Italy, with emphasis on Trentino-Alto Adige. Aside from fostering citizen participation in scientific endeavors and the enhanced literacy that ensues, BugMap helped uncover the invasion dynamics of H. halys and forecast its potential distribution in Trentino, all while coordinating technical monitoring and informing management strategies. The most promising agent currently under study for the classical biological control of H. halys is the Asian egg parasitoid Trissolcus japonicus. To assess the wasp’s potential non-target impacts, we investigated its foraging behavior in response to chemical traces ‘footprints’ deposited by its main host H. halys and by a suboptimal predatory species, the spined soldier bug, Podisus maculiventris. Wasps exhibited a ‘motivated searching’ when in contact with footprints originating from both species. However, T. japonicus arrestment was significantly stronger in response to H. halys footprints, compared with P. maculiventris, implying the presence of underlying chemical cues that shape its natural preferences. A series of GC-MS chemical analyses revealed that n-tridecane and (E)-2-decenal were more abundant in H. halys footprints and are probably the key components utilized by the wasp for short range host location. The function of the aforementioned compounds was studied, n-tridecane acted as an arrestant, prolonging T. japonicus residence time, whereas (E)-2-decenal fulfilled its presumed defensive role and repelled the wasp. These results shed new light on the chemical ecology of T. japonicus and help expand the understanding of parasitoid foraging and its implications for classical biological control. Moving to the other invader L. delicatula, an egg parasitoid Anastatus orientalis was reported attacking it at high rates in its native range in Eastern Asia and may play a key role in reducing its populations there. A series of bioassays revealed that wasps responded to footprints deposited by L. delicatula gravid females by initiating a strong searching behavior. Moreover, A. orientalis preferred to oviposit in egg masses with intact oothecae, suggesting that the host’s egg covering functions as a trigger for A. orientalis probing and oviposition. Thus, A. orientalis not only overcomes, but also reverses an important line of host structural defense for its own fitness gains. This dissertation discusses the benefits of combining citizen science with traditional monitoring, and the usefulness of decoding host-parasitoid interactions to design more efficacious management strategies of invasive insect pests.

1. Large rivers in the central United States experience a variety of ecological interactions. Both short- and long-term temporal changes affect both fish and zooplankton communities in rivers. Variation in diel patterns of predation could affect differences of behavior in prey. Long term temporal changes across seasons can lead to different areas of rivers providing growth or costing energy. Spatial changes also affect habitat quality and behaviors of the aquatic organisms within large rivers. Spatial variation can be dynamic and occur between longitudinally connected habitats or vary through different sections of the reach and can also change seasonally. 2. Invasive species have major economic and ecological impacts. In aquatic ecosystems, plankton are the base of the food web and a planktivore invader can cause major ecological disruptions. The Wabash River is a large free flowing river with a variable hydrology, which causes dramatic changes in habitat availability through time. Therefore, habitat usage, quality, and availability may differ for native and invasive species through time. The objectives of this study were to assess how habitat quality changes in a large, flashy, free-flowing river over time, and to compare the quantity and overlap of quality macrohabitat for invasive and native fish. Growth rate potential (GRP) was used to quantify habitat quality for Silver Carp (Hypophthalmichthys molitrix; invasive) and Gizzard Shad (Dorosoma cepedianum; native). To calculate GRP, bioenergetic models were used with monthly observations of food abundance (zooplankton, phytoplankton, and detritus), water temperature, dissolved oxygen, and water velocity of various habitat types from the Wabash River’s confluence with the Ohio River upstream to Terre Haute, Indiana, approximately 215 river miles. Negative GRP for both Silver Carp and Gizzard Shad occurred during spring and most of summer. However, in the fall, the majority of the river had a positive GRP for both species. Reduced flows and increases in food abundance were the cause for the switch from negative to positive GRP. There was a high degree of spatial overlap in positive GRP areas between Silver Carp and Gizzard Shad, suggesting that there is a high degree of competition. Acoustically tagged Silver Carp selected for areas predicted to have a positive GRP from the model presented in the study. This model showed that regulation of flows in hydrologically altered systems could potentially lower the impact of Silver Carp in those systems. With Silver Carp selecting for predicted habitats, a bioenergetics model can be used to inform commercial fishers where to focus effort to maximize catch.3. Temporal changes in rivers tend to be quantified at broad seasonal scales. However, river conditions including water flow, water temperature, dissolved oxygen, and availability of zooplankton prey may change daily. In large rivers, these conditions may change in a diel fashion between backwater and main channel habitats. To assess diel changes in the Illinois River, zooplankton, paired with mobile hydroacoustic surveys for fish were sampled from three main channel and three off-channel sites in the LaGrange reach every four hours in a twenty-four-hour period at different depths between October 22 and 26, 2018. Water depth, water temperature, water velocity, and fish (planktivore and nonplanktivore) densities were quantified during each sampling time. Water temperature and water velocity differed between the two habitat types. Water temperature was higher and water velocity was lower in the off-channel. Water temperature was colder in the morning in both the main channel and off-channel. Water velocity did not change throughout the day. The majority of the zooplankton community was comprised of rotifers which were less mobile than larger taxa and did not migrate. When evaluating the more mobile, large body zooplankton, time and depth affected copepod density in off-channel environments, where the deeper depth had a higher copepod density than the shallower depth. In contrast, only time of day affected off-channel cladoceran density, where densities increased at night. Fish did not exhibit diel patterns and the off-channel habitat had a higher density. The most likely mechanism behind the diel movements of the large bodied zooplankton was predation by planktivorous fish. The present study suggests that connections to the off-channel habitats in large rivers will promote quality habitat for both zooplankton and fish.