• Behavioural characteristics in phylogenetics : a case study using black fly (Diptera: Simuliidae) cocoon spinning behaviour

      Stuart, Alison E.; Department of Biological Sciences (Brock University, 1995-07-09)
      1-1 is torically, the predominan t method of reconstructing phylogenies has been through the use of morphological characters. There are new techniques now gaining acceptance, including molecular techniques al1d chromosomal information. Altl10ugh the study of behaviour has been used in a comparative framework, these analyses have, historically, been based on intuition. Hennig (1966) devised a neV\' method of reconstructing phylogenies which provided a 110ncircular method for formulating, testing and refining phylogenies. Subsequent s)Tstematists had virtually abandoned ecological and beha\lioural data as primary indicators of phylogenetic relationships (Brooks and McLennan 1991). Therefore, in a modern cladistic framework (sensu Hennig) the analysis of behavioural traits remains underrepresented as a method of reconstructing phylogenies. This thesis will reconstruct the phylogeny for species of black flies (Diptera: Simuliidae), using two steps. The first step is to thoroughl)' understand and explain the cocoon spinning in black fly larvae. There have bee115 previous descriptions of cocoon spinning, but all were incomplete or erroneous. The advances in technology, including video recorders and VCRs, have allowed this behaviour to be analyzed in great detail in 20 different species. A complete description of the cocoon spinning of Simulium \littatum is given. This description will be used as a template for the other species observed. The description and understanding of cococ)n spinning was the first step in undertaking a phylogenetic analysis using this behaviour. The behaviour was then broken down and analyzed, revealing 23 characters, 3 either qualitative and quantitative in nature. These characters were assessed in a cladistic framework (sensu Hennig) and a phylogenetic tree was reconstructed with a e.I of 0.91 and an R.I. of 0.96. This phylogenetic tree closely resembles a previously established pllylogenetic tree produced from morphological and cytological information. The importance of this result is the indication that, contrary to some authors, behavioural characters, if used properly, can add very informative characters to a data set.
    • Behavioural Thermoregulation and Energetics in Two Intermediate Hosts of Trematode Parasites

      Wang, Susan Yao Shan; Department of Biological Sciences
      Infection by macroparasites, such as trematodes (flatworms), can negatively impact survival of hosts such as larval amphibians, potentially altering host energy use in response to infection, and also through alterations of host behaviour that may increase infection tolerance or instead benefit the parasite. However, physiological consequences of macroparasite infections are not well studied, despite heavy parasite burdens in the field. The purpose of this work was to examine altered thermoregulatory behaviours in two taxa (snails and larval amphibians) used as intermediate hosts by trematodes, as well as to study the metabolism of naturally-infected tadpoles. Both infected and uninfected tadpoles (Lithobates sylvaticus and L. pipiens) and snails (Helisoma trivolvis) were placed in thermal gradients to observe thermal preferences in hosts. Oxygen consumption in naturally-infected bullfrog tadpoles (L. catesbeiana) was measured to determine whether macroparasites could impact host metabolism. The trematode-infected, L. sylvaticus tadpoles exhibited “behavioural fever” by choosing warmer temperatures by the end of the experiment compared to uninfected tadpoles, but this did not occur in L. pipiens. Active, infected snails also selected warmer temperatures relative to inactive snails and active uninfected snails. Trematode infection intensity did not affect respiration in L. catesbeiana tadpoles, but those with higher metabolic rates and larger fat bodies had lower parasite counts. These results suggest that behavioural fever may occur in ectotherms infected with macroparasites, but may be more important for species which are relatively intolerant of infection given that fever was not seen in L. pipiens. As infected snails selected warmer temperatures, this may be a case of parasite manipulation to increase production and emergence of infectious stages in warm microhabitats to facilitate transmission. Metabolic rate increased with fat body content, and larger fat bodies were observed in tadpoles with lower parasite intensity, suggesting more heavily parasitized animals had lower energy stores. Globally, infectious diseases are known to contribute to amphibian declines, thus more research is needed to understand the possible consequences of parasitism and mechanisms by which hosts to may defend themselves.
    • Behavioural Thermoregulation and Escape Behaviour: Investigating the Thermal Biology of Round Gobies

      Bridgeman, Justin; Department of Biological Sciences
      The invasive round goby (Neogobius melanostomus) has successfully colonized all of the Great Lakes since its discovery in the region in 1991, yet little is known about its thermal biology. The focus of this thesis was to examine the effect of acclimation to unseasonably warm temperatures on round goby behavioural thermoregulation, as well as behavioural and physiological performance during escapes with warm acute temperatures. Juvenile gobies were acclimated to either 21°C or 24°C for each set of experiments. I first examined goby thermal preference in a shuttlebox through their ability to escape from unfavourable temperatures. I found that escape temperatures were plastic following acclimation to a rise in 3°C rise in temperature (+3°C) and associated positively with acclimation temperature, even though gobies showed slightly lower-than-expected average escape temperatures in each acclimation treatment. Interestingly, acclimation to +3°C leads to lower exploratory behaviour in warm waters and lower overall activity levels during behavioural thermoregulation. In risky situations involving threat of predation, exploratory behaviour is often linked to boldness. Next I investigated exploratory swimming through two behavioural traits: ability to voluntarily enter a tunnel and subsequent swimming activity while being chased in a detour task. Detour tasks require a fish to swim down a narrow space and then detour to the left or right as they approach a barrier. A strong correlation between behavioural traits suggests the two behavioural traits are a good measure of risky swimming behaviour. With respect to the impact of warm acute temperatures, I observed an increase in strength of risky swimming behaviour following a rise in acute temperature of 6°C (+6°C). Finally, I examined burst swimming performance (C- and S-starts) during the detour task. While there was no observed effect of warm acute temperatures on most C- and S-start performance measures, there was a significant increase in S-start time to maximum velocity at +6°C. Along with the observed plasticity in strength of risky swimming behaviour, my findings showed that acclimation to +3°C shifted physiological performance of escapes. My findings provide a greater understanding of round goby physiological and behavioural functioning during short- and long-term rises in temperature.
    • Behavioural, mensural, and ecological correlates of polygyny in the eastern meadowlark (Sturnella magna)

      Siderius, Joanne A.; Department of Biological Sciences (Brock University, 1984-07-09)
      During 1982 and 1983 I studied male attributes and attributes of the territory of male Eastern Meadowlarks (Sturnella magna) in order to determine whether there was a correlation between any of the attributes investigated and the number of females attracted by a male. Seventeen males, nine of which were polygynous and eight monogamous, were studied in 1982 and sixteen males.of which .. seven were polygynous and nine ~onogamous, were studied in 1983. The study was conducted in Short Hills Park, 10 km southwest of St. Catharines, Ontario and was designed to compare two hypotheses: the "sexy son" hypothesis (Weatherhead and Robertson,1977) and the polygyny threshold model (Verner and Willson,1966, Orians, 1969). Male attributes investigated were male size and song behaviour. Six measures of male size were taken: weight, flattened and natural wing chord length, culmen length, bill depth and length of the tarsometatarsus. In 1983 song repertoire size and song versatility measures were investigated. Attributes of the territory studied were: territory size, density of plant stems, percentage plant cover and measures of vegetation structure. In 1983 Arthropods were collected from each territory and sorted according to taxonomic group and size. During 1983, territory attributes were sampled twice, once early and once later in the nesting season. Analysis of data involved univariate comparisons between monogamous and polygynous males using T-tests and multivariate comparisons were made using discriminant function analysis (DFA) and principle components analysis (PCA).No correlations were found between the number of females attracted with, .ny measure of male size or with me, .sures of song versatili or size of song repertoire. Also no correlation was found between terri size and the number of females nesting on a terri . Some attributes of the male's terri id distinguish between monog,mous and po s males of thistudy. Analysis of Arthropod numbers showed that e~ .eran counts were significantly great~r on polygynous territories, a1 the total numb~rs of Arthropods collected showed no s fico .nt differences between territories of monogamous and po males. DFA chose ear teran and Hymenopteran counts as multivariate discriminators; both variables we' e more vegetation revealed that there were no univariate differences between the two groups of males fOT 1982 stem densities, but ~ spp. and Solidago spp. were chosen DFA as multivariate discriminators. The total number of plant stems and of Vicia spp. stems were s ficantly the early 1983 ing on monogamous territories for however DFA found no multivariate discriminators" Variables concerned with the overall aspects of vegetation structure showed significant differences between territories of monogamous and polygynous males. DFA of the 1982 sampling of vegetation structure showed significantly greater mat depth and vegetation height on polygynous territories, a finding which was not supported, however, by peA. For the early 1983 sampling period, plant height was greater on polygynous territories. Multivariate analysis identified greater green cover on polygynous territories, greater ground cover on monogamous territories, and greater depth of mat material on monogamous territories as discriminators between territories of monogamous and polygynous males. A DFA on the major variables of the study showed no significant difference between the territories of monogamous and polygynous male Meadowlarks. Of the correlations found, some were for non-prey Arthr~ods, for cover plants with very small samples sizes, or for variables which were greater for monogamous males during one sampling period and polygynous males during the next. While multivariate discriminators were found, peA showed no grouping of monogamous or polygynous males according to any of the variables investigated. On the basis of the univariate and multivariate analysis of major variables, I concluded that there were no correlations between the number of females attracted with male attributes and no unambiguous correlation with attributes of the territory. My study does not unequivocally support either the "sexy son" or the polygyny threshold hypothesis.
    • Biochemical and histological investigations of viral localisation in the hypersensitive reaction of Phaselous vulgaris L. var Pinto to tobacco mosaic virus infection

      Stobbs, Lorne W.; Department of Biological Sciences (Brock University, 1975-10-02)
      STOBBS, Lorne,W ABSTRACT Biochemical and Histological Investigations of viral localisation in the hypersensitive reaction of Phaseolus vulgaris L. var Pinto to tobacco mosaic virus infection. The infection of Phaseolus vulgaris L. var Pinto with tobacco mosaic virus (TMV) results in the production of distinct necrotic lesions confining the virus to restricted areas of the leaf surface. Biochemical and histological changes in the leaf tissue as a result of infection have been described. Trace accumulations of fluorescent metabolites, detected prior to lesion expression represent metabolites produced, by the cell in response to virus infection. These substances, are considered to undergo oxidation and in diffusing into adjacent cells, react with cellular constituents causing the death of these cells. Such cellular necrosis in advance of infection effectively limits virus spread. Chromatographic studies on extracts from TMV infected Pinto bean leaf tissue suggests that a number of extra-fluorescent metabolites produced on lesion'expression represent end products of phenolic oxidation r,eactionsoccurring earlier in these cells. Inhibition of phenolic oxidation by ascorbate infiltration or elevated temperature treatment resulted in the absence of extra-fluorescent metabolites and the continued movement of virus in the absence of necrosis. Further studies with i ascorbate infiltration indicated that irreversible necrotic events were determined as early as 12 tci 18 hrs after viral inoculation. Histochemical tests indicated that callose formation was initiated at this time, and occurred in response to necrotisation. Inhibition of necrosis by either ascorbate infiltration or elevated temp8rature treatment resulted in the absence of callose deposition. Scanning electron'micrographs of infected tissue revealed severe epidermal and palisade cell damage. Histochemical tests indicated extensive callose formation in cells bordering the lesion, and suggested the role of callose iTh the blockage of intercellular connections limiting virus movement. The significance of these cellular changes is discussed. ii
    • A biochemical predictor of performance during mesophilic anaerobic fermentation of starch wastewater

      Goodin, John D.; Department of Biological Sciences (Brock University, 1985-07-09)
      The aim of this study was to determine the potential of biochemical parameters, such as enzyme activity and adenosine triphosphate (ATP) levels, as monitors of process performance in the Upflow Anaerobic Sludge Blanket (UASB) reactor utilizing a starch wastewater. The acid and alkaline phosphatase activity and the ATP content of the UASB sludge were measured in response to changes in flow rate and nutrient loading. Conventional parameters of process performance, such as gas production, acetic acid production, COD, phosphorus, nitrogen and suspended solids loadings and % COD removal were also monitored. The response of both biochemical and conventional parameters to changing process conditions was then compared. Alkaline phosphatase activity exhibited the highest activity over the entire study perioda A high suspended solids loading was observed to upset the system in terms of gas production, acetic acid production and % COD removala The initial rate of increase in alkaline phosphatase activity following an increase in loading was four times as great during process upset than under conditions of good performance. The change in enzyme actiVity was also more sensitive to process upset than changes in acetic acid production. The change in ATP content of the sludge with time suggested that enzyme actiVity was changing independently of the actual viable biomass present. The bacterial composition of the anaerobic sludge granules was similar to that of other sludge bed systems, at the light and scanning electron microscope level. Isolated serum bottle cultures produced several acids involved in anaerobic carbohydrate metabolism. The overall performance of the UASB system indicated that higher loadings of soluble nutrients could have been tolerated by the system.
    • Bird depredation of grapes in Niagara vineyards : a novel approach to identifying spatial and temporal trends /

      Department of Biological Sciences (Brock University, 1999-05-21)
      Although local grape growers view bird depredation as a significant economic issue, the most recent research on the problem in the Niagara Peninsula is three decades old. Peer-reviewed publications on the subject are rare, and researchers have struggled to develop bird-damage assessment techniques useful for facilitating management programmes. I used a variation of Stevenson and Virgo's (1971) visual estimation procedure to quantify spatial and temporal trends in bird damage to grapes within single vineyard plots at two locations near St. Catharines, Ontario. I present a novel approach to managing the rank-data from visual estimates, which is unprecedented in its sensitivity to spatial trends in bird damage. I also review its valid use in comparative statistical analysis. Spatial trends in 3 out of 4 study plots confirmed a priori predictions about localisation in bird damage based on optimal foraging from a central location (staging area). Damage to grape clusters was: (1) greater near the edges of vineyard plots and decreased with distance towards the center, (2) greater in areas adjacent to staging areas for birds, and (3) vertically stratified, with upper-tier clusters sustaining more damage than lower-tier clusters. From a management perspective, this predictive approach provides vineyard owners with the ability to identify the portions of plots likely to be most susceptible to bird damage, and thus the opportunity to focus deterrent measures in these areas. Other management considerations at Henry of Pelham were: (1) wind damage to ice-wine Riesling and Vidal was much higher than bird damage, (2) plastic netting with narrow mesh provided more effective protection agsiinst birds than nylon netting with wider mesh, and (3) no trends in relative susceptibility of varietals by colour (red vs green) were evident.
    • Body size in the field cricket Gryllus integer (Orthoptera : Gryllidae) :heritability and male mating success

      McGowan, Elizabeth Jean.; Department of Biological Sciences (Brock University, 1986-07-09)
      The influence of male body weight on the aggressive and mating behaviour of male Gryllus integer was studied under laboratory conditions. The relationship between adult age and weight was first determined; female weight increased and male weight decreased with age. Virgin males that had been isolated since the adult molt were paired for similar age and a difference in weight of greater than 200 mg. Paired males and a virgin female were observed in a glass arena for 24 minutes or until a mating occurred. Larger males mated significantly more often than smaller males. Larger males attacked more often, were more successful in aggressive encounters and had more contact with the female. Males that did not mate had lower rates of courtship and mounts than males that mated. Females in trials that did not result in a mating were signifcantly heavier than females in trials that resulted in a mating. Larger males that mated were significantly closer in weight to the weight of the female than larger males in trials that did not result in a mating. Larger males in trials that did not result in a mating had higher rates of aggressive stridulation than larger males that mated. Male weight is therefore important in mating success; fitness traits should theoretically show low genetic variability. However, significant heritability values were found for live weight, dry weight, head width, pronotum width and length, hind femur length and forewing length when estimated from the regression of offspring on mid-parent values, offspring and female and male values separately and full-sib correlations. The heritability of hind femur width was significant when estimated from the regression of offspring on male parent and from full-sib correlations. Heritability estimates of forewing length were significantly higher when estimated from the regression of offspring on female parent than when estimated from the regression of offspring on male parent. High phenotypic, genetic and environmental correlations were found between all pairs of traits. Data on male mating success and the heritability of fitness traits were discussed in terms of the maintenance of genetic variability.
    • Breeding parameters of great cormorants (Phalacrocorax carbo carbo) at mixed species colonies on Prince Edward Island, Canada

      Hogan, Geoffrey Gordon.; Department of Biological Sciences (Brock University, 1979-07-09)
      Breeding parameters of Great Cormorants (PkaZac/iOCOfiCLX CCUibo dCUtbo) and Double-crested Cormorants (P. CLU/uXuA CMJhLtllb) were examined at two mixed species colonies at Cape Tryon and Durell Point, Prince Edward Island from 1976 to 1978. Differential access to nests at the two colony sites resulted in more complete demographic data for P. CCUibo than for P. CLUJiituA. In 1911j P. CCtfibo was present at both colonies by 21 March, whereas P. auAAJtuA did not return until 1 April and 16 April at Cape Tryon and Durell Point, respectively. Differences in the arrival chronology by individuals of each species and differences in the time of nest site occupation according to age, are suggested as factors influencing the nest site distribution of P. CXUtbo and P. aiVtituA at Cape Tryon. Forty-eight P. dOJtbo chicks banded at the Durell Point colony between 19 74 and 19 76 returned there to nest as two- to four-year olds in 19 77 and 19 78. Unmarked individuals with clutch-starts in April were likely greater than four years old as all marked two to four-year olds (with one possible exception) in 19 77 and 1978 had clutch-starts in May and June. Seasonal variation in the breeding success of P. dOJibo individuals was examined at Durell Point in 1977. Mean clutch-size, hatching success and fledging success exhibited a seasonal decline. Four- and 5-egg clutches represented the majority (75%) of all P. CCUibo clutches at Durell Point in 1977 and had the highest reproductive success (0.48 and 0.43 chicks fledged per egg laid respectively). Smaller clutches produced small broods with significantly higher chick mortality while larger clutches suffered high egg loss prior to clutch completion.
    • Broad reduction and adoption in ring-billed gulls (Larus Delaworensis): the potential for inergenerational conflict

      Woulfe, Michelle.; Department of Biological Sciences (Brock University, 1989-07-09)
      Patterns of intra-clutch egg size variation and intra-clutch hatch intervals in the Ring-billed gull (Larus delawarensis) were documented during the peak nesting period of two consecutive breeding seasons, at a colony near Port Colborne, Ontario. Egg size decreased with laying order; third laid eggs were significantly smaller than first laid eggs. Hatching of the third egg was delayed from that of first and second eggs. Intraclutch egg size differences established initial size disparities among chicks at hatch. Hatch intervals further exaggerated size disparities during the early post brood completion period. Competitive asymmetries among chicks were associated with increased mortality rates among third hatched chicks despite the lack of evidence of a sibling feeding hierarchy. Fledging success in 1987 was greater than in 1988. A "brood reduction strategy" appears to have enabled parents in 1987, to obtain an extra unit of reproductive fitness, while in 1988 parents were often unable to raise the entire brood and third chicks likely represented insurance reproductive value. Experimental broods (1988) were created in which hatch intervals were double those of natural intervals. The size disparities among chicks were significantly greater than in control broods, and the pattern of mortality among chicks suggested that first chicks benefited at a cost to second and third chicks. Parents of peak experimental broods achieved a fledging success rate similar to that of control broods. Characteristics of chick adoptions were also recorded. In each study year, 9 chicks abandoned their natal territories, 6 of which were adopted. Chicks consistently established themselves into broods where they were older than resident chicks. No direct evidence of cost to foster parents, or benefits to adopted chicks was obtained, although fledging success of adopted chicks was high.
    • The Catharanthus roseus 16-hydroxytabersonine O-methyltransferase involved in vindoline biosynthesis /

      Levac, Dylan.; Department of Biological Sciences (Brock University, 2008-06-29)
      Madagascar periwinkle (Catharanthus roseus) produces the well known and remarkably complex dimeric anticancer alkaloids vinblastine and vincristine that are derived by coupling vindoline and catharanthine monomers. This thesis describes the novel application of carborundum abrasion (CA) technique as a tool for large scale isolation of leaf epidermis enriched proteins. This technique was used to facilitate the purification to apparent homogeneity of 16-hydroxytabersonine-16-0-methyltransferse (l60MT) that catalyses the second step in the 6 step pathway that converts tabersonine into vindoline. This versatile tool was also used to harvest leaf epidermis enriched mRNAs that facilitated the molecular cloning of the 160MT. Functional expression and biochemical characterization of recombinant 160MT enzyme showed that it had a very narrow substrate specificity and high affinity for 16-hydroxytabersonine, since other closely related monoterpene indole alkaloids (MIAs) did not act as substrates. In addition to allowing the cloning of this gene, CA technique clearly showed that 160MT is predominantly expressed in Catharanthus leaf epidermis, in contrast to several other OMTs that appear to be expressed in other Catharanthus tissues. The results provide compelling evidence that most of the pathway for vindoline biosynthesis including the 0- methylation of 16-hydroxytabersonine occurs exclusively in leaf epidermis, with subsequent steps occurring in other leaf cell types. Small molecule O-methyltransferases (OMTs) (E.C. catalyze the transfer of the reactive methyl group of S-adenosyl-L-methionine (SAM) to free hydroxyl groups of acceptor molecules. Plant OMTs, unlike their monomeric mammalian homologues, exist as functional homodimers. While the biological advantages for dimer fonnation with plant OMTs remain to be established, studies with OMTs from the benzylisoquinoline producing plant, Thalictrum tuberosum, showed that co-expression of 2 recombinant OMTs produced novel substrate specificities not found when each rOMT was expressed individually (Frick, Kutchan, 1999) . These results suggest that OMTs can fonn heterodimers that confer novel substrate specificities not possible with the homodimer alone. The present study describes a 160MT model based strategy attempting to modify the substrate specificity by site-specific mutagenesis. Our failure to generate altered substrate acceptance profiles in our 160MT mutants has lead us to study the biochemical properties ofhomodimers and heterodimers. Experimental evidence is provided to show that active sites found on OMT dimers function independently and that bifunctional heterodimeric OMTs may be fonned in vivo to produce a broader and more diverse range of natural products in plants.
    • Cellular Mechanisms Underlying Retinoic Acid-Induced Growth Cone Guidance During Neuronal Regeneration

      Johnson, Alysha; Department of Biological Sciences
      During the period of neuronal development, neurons must make correct synaptic connections with their appropriate targets. The intricate connections of the nervous system are established in part by growth cones, located at the tips of extending neurites. These unique structures are essential for axon pathfinding and target cell selection by sensing and integrating numerous guidance cues from their environment. Retinoic acid, the active metabolite of vitamin A, is an important regulator of neurite outgrowth during vertebrate development, but there is substantial evidence that it also plays a role in axon guidance. Previous studies have provided preliminary evidence of a potential role of retinoid receptors in mediating the chemotropic effects of retinoic acid. In this study, I demonstrated that a synthetic retinoic acid receptor agonist was able to mimic the effects of retinoic acid in inducing growth cone turning. I also examined the intracellular pathways activated by retinoic acid that induce changes in growth cone behaviour. Previously it has been shown that retinoic acid-induced growth cone turning of invertebrate motorneurons requires local protein synthesis and calcium influx, similar to other known guidance cues in the central nervous system. However, the signalling pathways that link calcium influx to the regulation of cytoskeletal dynamics involved in growth cone turning are not currently known. Here, I examined potential effectors downstream of retinoic acid and have provided evidence that the intracellular pathways likely involve the Rho GTPases, Rac and Cdc42. I demonstrated that the inhibition of Rac or Cdc42 prevented growth cone turning towards retinoic acid. However, it was shown that the involvement of Rac differed depending on whether the growth cones maintained communication with the cell body or not. Moreover, the inhibition of Cdc42 not only blocked growth cone turning towards retinoic acid, but also induced a switch in growth cone responsiveness from attraction to repulsion. Overall, these studies provide new knowledge of the mechanisms underlying growth cone pathfinding by retinoids during nervous system development and regeneration.
    • Changes in the magnitude and pattern of translocation of photoassimilated ¹CO in soybean plants following an acute exposure to gamma radiation /

      Schefski, Hans Juergen.; Department of Biological Sciences (Brock University, 1974-06-15)
      Young soybean plants (Glycine ~. L. cultivar Harosoy '63), grown under controlled conditions, were exposed to gamma radiation on a single occasion. One hour following exposure to 3,750 rads, the mature trifoliate leaf of the soybean plant was isolated in a closed system and permitted to photoassimilate approximately 1-5 pCi of 14C02 for 15 minutes. After an additional 45 minute-period, the plant was sacrificed and the magnitude of translocation and distribution pattern of 14C determined. In the non-irradiated plants 18~ of the total 14C recovered was outside the fed leaf blades and of this translocated 14c, 28~ was above the node of the fed leaf, 38~ in the stem below the node, 28~ in the roots and 7~ in the petiole. As well, in the irradiated plants, a smaller per cent (6~) of the total 14 C recovered was exported out of the source leaf blades. Of this translocated 14c , a smaller per cent (20~) was found in the apical region above the node of the source leaf and a higher per cent (45~) was recovered from the stem below the node and in the petiole (11~). The per cent of exported 14 C recovered from the root was unaffected by the radiation. Replacement of the shoot apex with 20 ppm IAA immediately following irradiation, only J partially increased the magnitude of translocation but did completely restore the pattern of distribution to that observed in the non-irradiated plants. From supplementary studies showing a radiationinduced reduction of photosynthetic rates in the source leaf and a reduction of the cumulative stem and leaf lengths in the apical sink region, the observed effects of radiation on the translocation process have been correlated to damage incurred by the source and sink regions. These data suggest that the reduction in the magnitude of translocation is the result of damage to both the source and sink regions rather than the phloem conducting tissue itself, whereas the change in the pattern of translocation is probably the result of a reduced rate of 14C-assimilate movement caused by a radiation-induced decrease of sink metabolism, especially the decrease in the metabolism of the apical sink.
    • Characterising Behavioural Thermoregulation in the Bearded Dragon: The Role of TRPM8

      Berman, Jacob; Department of Biological Sciences (Brock University, 2013-05-06)
      Temperature regulation is a necessary part of maintaining life, as most biological processes are influenced by temperature. ThermoTRP channels are considered the primary thermosensors in endotherms, but little is known regarding their function in ectotherms. The goal of this study is to establish TRPM8, a cold sensing channel, as a participant in normal thermoregulation of the bearded dragon (Pogona vitticeps), an ectotherm. Animals were placed inside a ramping temperature shuttle box to assess the common behavioural thermoregulatory strategy of shuttling. Shuttling involves the periodic movement between cold and warm environments to maintain body temperature at moderate levels. The temperatures for cold and warm escapes represent sensory thresholds for inducing the shuttling thermoeffector. Animals were administered with: 1) an injection of the TRM8 antagonist capsazepine, 2) an injection of the TRPM8 agonist menthol, and 3) menthol applied topically. No effect was observed with injected drugs, but topical menthol resulted in a 2-3oC rise in the ambient temperature threshold and 1-2oC rise in skin temperature threshold for escape from the cold compartment. In an additional experiment, gaping behaviour, a warm temperature thermoregulatory strategy, was assessed. No effect was observed in this behaviour when the same dose of menthol was applied topically. These results point to a role for TRPM8 only in thermoregulation as it relates to cold temperature sensation in lizards, since it does not participate in regulating warm temperature behaviours such as gaping.
    • Characterization and protein fingerprinting of Botrytis cinerea isolates /

      Aljourmi, Ismail.; Department of Biological Sciences (Brock University, 1999-05-21)
      Botrytis cinerea isolates collected from Niagara region were treated with different concentrations of the fiingicide, iprodione to test their sensitivity to this fungicide. These Botrytis cinerea isolates were divided into two groups according to their sensitivity to iprodione. Those isolates whose growth was inhibited by iprodione at concentrations < 2|i,g/nil were classified as sensitive isolates. Isolates that were able to show considerable growth at 2|j,g/ml iprodione were classified as resistant isolates. Resistant and sensitive isolates were compared for their morphological and growth characteristics, conidial germination, virulence on grape berries and protein banding profiles. The fungicide iprodione at a concentration of 2|xg/nil inhibited mycelial growth, sporulation and conidial germination of sensitive isolates but not those of resistant isolates. The inhibitory effect of the fungicide was greater on mycelial growth than on conidia germination of the sensitive isolates. Sensitive isolates produced no sclerotia whereas resistant isolates produced large number of sclerotia. The fungicide iprodione affected sclerotial production in the resistant isolates. The number of sclerotia was decreased by the increase of iprodione in the medium. Sporulation of resistant isolates was improved significantly in the presence of iprodione. The resistant isolates were as virulent as the sensitive isolates on grape berries. The sensitive and resistant isolates showed similar protein banding profiles in the absence of iprodione in polyacrylamide gel electrophoresis studies. Similar protein profiles were also observed when these isolates were grown in the presence of low iprodione concentration (0.5|ig/nil). However, in the presence of concentration (0.5|ig/nil). However, in the presence of iprodione at concentration of 5|Xg/nil, one protein band with approximate molecular weight of 83 KDa was present in the growing resistant isolates (and the controls) but was missing in the inhibited sensitive isolates.
    • Characterization of black fly (Diptera: Simuliidae) silk proteins

      Viel, Patrick; Department of Biological Sciences (Brock University, 2014-09-05)
      Black fly (Simuliidae) silk is produced by the larvae and pharate pupae and is used for anchorage and cocoon production. There exists limited information on simuliid silks, including protein composition and genetic sequences encoding such proteins. The present study aimed to expand what is known about simuliid silks by examining the silks of several simuliid species and by making comparisons to the silk of non-biting midges (Chironomidae). Silk glands were dissected out of larval and pupal simuliids, and protein contents were separated by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and visualized with silver stain. Protein contents were compared by mass in kilodaltons (kDa) between life stages and among species. Polymerase chain reaction (PCR) was used to expand upon known gene sequence information, and to determine the presence of genes homologous to chironomid silk. SDS-PAGE of cocoons revealed the presence of a 56 kDa and a 67 kDa protein. Silk gland contained as many as 28 different proteins ranging from 319 kDa to 8 kDa. Protein profiles vary among species, and group into large (>200), intermediate(>100), and small (<100) protein classes as is found in chironomids. It is likely that silk evolved in a common ancestor of simuliids and chironomids
    • Characterization of plant, leafhopper, and spider communities in perimeter plantings and vineyards in the Niagara region

      Hughes, Margaret Moira; Department of Biological Sciences
      Vineyards are large agroecosystems associated with high external inputs and intervention leading to local decreases in biodiversity. With trends towards sustainable agriculture, there is a push to maximize natural ecosystem functions through methods of on-farm diversification, such as perimeter plantings. Increased plant diversity has been found to increase the ability to exploit natural ecosystem functions such as pest management, through the bottom-up control of species richness displayed by increased plant species richness. The aim of this thesis was to investigate the effect of perimeter plantings on vineyard plant and invertebrate communities. I hypothesized that perimeter plantings would have greater plant diversity and habitat complexity than vineyard interiors. Perimeter plantings would also support increased assemblages of natural enemies with decreased pest populations when compared to the vineyards. Plant communities in the perimeter plantings and the vineyards were first surveyed using transects within the perimeters and perpendicular transects from the perimeters towards the interior of the vineyards. Invertebrate communities were also surveyed within the perimeter plantings and adjacent vineyards, focusing on leafhoppers and spiders. Seven commercially operating vineyards throughout the Niagara region were surveyed both within the perimeter planting and adjacent vineyard during the 2018-growing season. It was found that perimeter plantings not only had increased plant species richness and functional diversity, but the species and functional composition within the perimeters differed from vineyard interiors. This indicated that perimeter plantings did not increase weed pressure but allowed for increased habitat complexity adjacent to the vineyards. Leafhoppers showed significantly higher abundance in vineyard interiors than perimeter plantings, and as distance from perimeter planting increased, leafhopper abundances also increased. Spiders were more abundant in perimeter plantings, decreasing in abundance with distance from perimeter. Overall, the results suggest that perimeter plantings have the ability to support biological pest control, while not increasing both weed or pest pressure observed within vineyards.
    • Characterization of the chitinolytic system during the mycoparasitic interaction between Trichoderma aggressivum f. aggressivum and different host strains of Agaricus bisporus /

      Guthrie, Jennifer L.; Department of Biological Sciences (Brock University, 2003-05-19)
      Green mould is a serious disease of commercially grown mushrooms, the causal agent being attributed to the filamentous soil fungus Triclzodenna aggressivum f. aggressivu11l and T. aggressivum f. ellropaellm. Found worldwide, and capable of devastating crops, this disease has caused millions of dollars in lost revenue within the mushroom industry. One mechanism used by TricllOdenlla spp. in the antagonism of other fungi, is the secretion of lytic enzymes such as chitinases, which actively degrade a host's cell wall. Therefore, the intent of this study was to examine the production of chitinase enzymes during the host-parasite interaction of Agaricus bisporus (commercial mushroom) and Triclzodemza aggressivum, focusing specifically on chitinase involvement in the differential resistance of white, off-white, and brown commercial mushroom strains. Chitinases isolated from cultures of A. bisporus and T. aggressivu11l grown together and separately, were identified following native PAGE, and analysis of fluorescence based on specific enzymatic cleavage of 4-methylumbelliferyl glucoside substrates. Results indicate that the interaction between T. aggressivulll and A. bisporus involves a complex enzyme battle. It was determined that T. aggressivum produces a number of chitinases that appear to correlate to those isolated in previous studies using biocontrol strains of T. Izarziallilm. A 122 kDa N-acetylglucosaminidase of T. aggressivu11l revealed the highest and most variable activity, and is therefore believed to be an important predictor of antifungal activity. Furthermore, results indicate that brown strain resistance of mushrooms may be related to high levels of a 96 kDa N-acetylglucosaminidase, which showed elevated activity in both solitary and dual cultures with T. aggressivum. Overall, each host-parasite combination produced unique enzyme profiles, with the majority of the differences seen between day 0 and day 6 for the extracellular chitinases. Therefore, it was concluded that the antagonistic behaviour of T. aggressivli1ll does not involve a typical response, always producing the same types and levels of enzymes, but that mycoparasitism, specifically in the form of chitinase production, may be induced and regulated based on the host presented.
    • Characterization of the phosphorylation of thylakoid membrane proteins from cyanobacterium synechococcus sp. PCC 6301 in light state 1 and light state 2

      Li, Sida.; Department of Biological Sciences (Brock University, 1992-07-09)
      The distribution of excitation energy between the two photosystems (PSII and PSI) of photosynthesis is regulated by the light state transition. Three models have been proposed for the mechanism of the state transition in phycobilisome (PBS) containing organisms, two involving protein phosphorylation. A procedure for the rapid isolation of thylakoid membranes and PBS fractions from the cyanobacterium Synechococcus m. PCC 6301 in light state 1 and light state 2 was developed. The phosphorylation of thylakoid and soluble proteins rapidly isolated from intact cells in state 1 and state 2 was investigated. 77 K fluorescence emission spectra revealed that rapidly isolated thylakoid membranes retained the excitation energy distribution characteristic of intact cells in state 1 and state 2. Phosphoproteins were identified by gel electrophoresis of both thylakoid membrane and phycobilisome fractions isolated from cells labelled with 32p orthophosphate. The results showed very close phosphoprotein patterns for either thylakoid membrane or PBS fractions in state 1 and state 2. These results do not support proposed models for the state transition which required phosphorylation of PBS or thylakoid membrane proteins.
    • Characterization of the state transition in the cyanobacterium synechococcus sp. 7002 and a phycobilisome-less Mutant

      Brimble, K. Scott.; Department of Biological Sciences (Brock University, 1989-10-02)
      ABSTRACT Photosynthetic state transitions were investigated in the cyanobacterium Synechococcus sp. PCC 7002 in both wild-type cells and mutant cells lacking phycobilisomes. Preillumination in the presence of DCMU (3(3,4 dichlorophenyl) 1,1 dimethyl urea) induced state 1 and dark adaptation induced state 2 in both wild-type and mutant cells as determined by 77K fluorescence emission spectroscopy. Light-induced transitions were observed in the wildtype after preferential excitation of phycocyanin (state 2) or preferential excitation of chlorophyll .a. (state 1). The state 1 and 2 transitions in the wild-type had half-times of approximately 10 seconds. Cytochrome f and P-700 oxidation kinetics could not be correlated with any current state transition model as cells in state 1 showed faster oxidation kinetics regardless of excitation wavelength. Light-induced transitions were also observed in the phycobilisomeless mutant after preferential excitation of short wavelength chlorophyll !l. (state 2) or carotenoids and long wavelength chlorophyll it (state 1). One-dimensional electrophoresis revealed no significant differences in phosphorylation patterns of resolved proteins between wild-type cells in state 1 and state 2. It is concluded that the mechanism of the light state transition in cyanobacteria does not require the presence of the phycobilisome. The results contradict proposed models for the state transition which require an active role for the phycobilisome.