Serine protease inhibitors (serpins) are a large superfamily of proteins that regulate critical proteolytic pathways by inhibiting serine proteases. Tick-encoded serpins are thought to play a vital role in the feeding process. To determine the relationship of Amblyomma americanum serpin 6 (S6) to tick feeding regulation, this study attempted to define the biological significance of this molecule through transcription and protein expression profiles, biochemical characterization of recombinant s6 (rS6), and the effects of in vivo post-transcriptional gene silencing on blood meal acquisition and fecundity. Transcriptional analysis revealed that S6 mRNA is ubiquitously expressed in unfed and partially fed ticks through the initial 5 days of the feeding period. S6 mRNA abundance in dissected tick organs showed a 3.7, 3.4, and 1.7- fold upregulation from 24 h to 96 h in the salivary gland (SG), midgut (MG) and the carcass (CA) remnant after removal of SG, MG respectively before downregulating at 120 h. Native S6 protein is downregulated in response to tick feeding, with correlation between transcription and protein expression profiles only consistent from the unfed to 48 h. Similarly, S6 protein expression in dissected female tick tissues is reduced as feeding progresses, with S6 being identified in SG, MG, ovary (OV), and CA from 24 h until 72 h. Biochemical characterization of S6 was not achieved, as rS6 did not form an irreversible complex when incubated with chymotrypsin or trypsin. Although complete silencing of S6 and S6/S17 mRNA was achieved, post-transcriptional gene knockdown had no effect on tick feeding efficiency or fecundity. These findings have been discussed in regards to the development of a vaccine against A. americanum and necessary future studies have been suggested for further characterization and assessment of biological significance.

Two studies were conducted to evaluate the presence of tick-borne bacterial agents in Amblyomma americanum, lone star tick (LST), and various wildlife in Mississippi. Adult LSTs had DNA evidence of Ehrlichia chaffeensis (3.7%), E. ewingii (6.3%), and Borrelia lonestari (2.6%), while both larval (24.3%) and adult (43.5%) LSTs were positive for a Rickettsia spp. by polymerase chain reaction (PCR). White-tailed deer (WTD) were the only wildlife PCR positive for E. chaffeensis (18.8%), B. lonestari (3.1%), and Anaplasma phagocytophilum (3.1%). In addition, WTD had the highest seroprevalence to B. lonestari (19.3%) and E. chaffeensis (43.9%) antigens while raccoons had the highest seroprevalence to spotted fever group rickettsiae (R. parkeri antigen) (73.7%). These studies demonstrate evidence of potentially zoonotic tick-borne agents in LSTs and wildlife in Mississippi underscoring the importance of monitoring these agents for human and animal health.

With advances in molecular technology, the study of human ageing has turned to DNA for answers as to how humans age. Due to the size of the human genome and the longevity of humans, organisms with smaller genomes and shorter lifespans have frequently been the center of research studies in ageing. Studies of Drosophila melanogaster, Caenorhabditis elegans, yeast, and mice have uncovered specific genes that up and down regulate with age and stress. Research has yet to produce, however, results from an organism known for its longevity. Amblyomma americanum is an excellent candidate for this, as it can survive for years unfed. Two groups of 75 unfed adult A. americanum were monitored in a control environment of 85% relative humidity and an experimental environment designed to induce physiological stress at 75% relative humidity. Five ticks were tested for transcript abundance of five candidate ageing genes initially and at the 25th, 75th, and 95th percent mortality. These tests provided evidence that Amblyomma americanum undergoes changes in gene expression with age on a genetic level.

With advances in molecular technology, the study of human ageing has turned to DNA for answers as to how humans age. Due to the size of the human genome and the longevity of humans, organisms with smaller genomes and shorter lifespans have frequently been the center of research studies in ageing. Studies of Drosophila melanogaster, Caenorhabditis elegans, yeast, and mice have uncovered specific genes that up and down regulate with age and stress. Research has yet to produce, however, results from an organism known for its longevity. Amblyomma americanum is an excellent candidate for this, as it can survive for years unfed. Two groups of 75 unfed adult A. americanum were monitored in a control environment of 85% relative humidity and an experimental environment designed to induce physiological stress at 75% relative humidity. Five ticks were tested for transcript abundance of five candidate ageing genes initially and at the 25th, 75th, and 95th percent mortality. These tests provided evidence that Amblyomma americanum undergoes changes in gene expression with age on a genetic level.

Objetivo: El objetivo del presente trabajo fue determinar el efecto citoprotector y antisecretor del extracto acuoso de Solanum americanum Mill (hierba mora) en ratas con úlcera gástrica inducida y observar la presencia de reacciones adversas. Métodos: Se emplearon 72 ratas fueron divididas en grupos de 6. Para evaluar el efecto citoprotector, la úlcera fue inducida administrando indometacina 30mg/kg; para evaluar el efecto antisecretor se realizó la ligadura de píloro y para evaluar las reacciones adversas se administró el extracto durante dos meses; las dosis administradas de extracto fueron de 200mg/kg y 400mg/kg, las cuales fueron comparadas con el omeprazol a dosis de 10mg/kg. Resultados: El tratamiento con extracto de S. americanum Mill a dosis de 400mg/kg de peso, demostró efecto citoprotector, disminuyendo en 67% los indicadores de congestión, edema y hemorragia, inducidas con indometacina, sin embargo el omeprazol disminuyó en 67% los indicadores de congestión y hemorragia y en 100%, el indicador de edema. En ligadura de píloro, el extracto acuoso de S. americanum M. a dosis de 400mg/kg de peso, demostró efecto antisecretor disminuyendo el volumen de la secreción gástrica en un 66% y aumentando el pH en un 163%; comparado con omeprazol que disminuyó la secreción gástrica en un 83.6% e incrementó el pH en un 201.5%. En la determinación de efectos adversos, S. americanum M. demostró ser seguro a dosis de 400mg/kg de peso. Conclusión: En las condiciones experimentales, el extracto acuoso de S. americanum M. ha demostrado tener efecto antisecretor y citoprotector en ratas con inducción de úlcera gástrica, y con mínimos efectos adversos. / Aim: The aim of this study was to determine the cytoprotective and antisecretory effect of extract aqueous of Solanum americanum Mill (hierba mora) in rats with gastric ulcer induced and to observe the presence of adverse reactions. Methods: We used 72 rats were divided en groups of 6. For the cytoprotective effect, the ulcer was induced by administration of indomethacin 30mg/kg b.w.; the antisecretory effect by pylorus ligation and to evaluate the adverse reactions the extract was administered for two months, the doses of extract were 200mg / kg and 400mg/kg, which were compared with omeprazole at a dose of 10mg/kg. Results: Treatment with extract of S. americanum Mill at a dose of 400mg/kg b.w., showed cytoprotective effect, decreasing in 67% the indicators of congestion, edema and hemorrhage induced with indomethacin, however omeprazole decreased 67% the indicators of congestion and hemorrhage, and 100% the indicator of edema. In pylorus-ligated, the extract aqueous of S. americanum Mill a dose of 400mg/kg b.w., showed antisecretory effect, decreasing the volume of gastric secretion in 66% and increasing pH in 163%, and the omeprazole reduced the gastric acid secretion in 83.6% and increased the pH in 201.5%. In the determination of adverse effects, S. americanum Mill proved to be safe at doses of 400mg/kg b.w. Conclusion: In the experimentals conditions, the extract aqueous of S. americanum Mill possesses antisecretory and cytoprotective effect in rats with induced gastric ulcer, and with minimal side effects.

Infestation of cattle by Lone Star ticks, Amblyomma americanum, leads to damage of hides intended for leather, weight loss, infertility, and potentially death of cattle, which contribute to production losses for farmers. Public concerns regarding chemical residues in food and the environment necessitate development of chemical-free alternative tick controls, such as breeding for tick-resistant phenotypes and developing anti-tick vaccines. Thus, the goal of this study was elucidation of mechanisms that mediate immune responses in cattle infested with A. americanum using gene expression techniques. Methods for isolation of total RNA from bovine tick bite-site biopsies and blood leukocytes were optimized to provide RNA suitable for gene expression studies. Tick bite-site biopsies (6 mm) and blood leukocytes were collected from a total of 13 calves (N=6, Group 4 and N=7, Group 5 calves) during experimental tick infestations to determine A. americanum tick-susceptible and -resistant phenotypes. Microarray experiments compared gene expression in tick bite-sites from tick-susceptible, moderately tick-resistant, and highly tick-resistant calves. A total of 35 genes were profiled in tick bite-site biopsies and 12 genes were evaluated in blood leukocytes via gene-specific qRT-PCR assays, and analyzed for each phenotype and for each group of calves as a whole. Analysis of microarray data revealed differential expression of IL-1R-mediators among the three cattle phenotypes. Expression profiles generated by qRT-PCR for TLR-mediating genes such as TLR2, TLR4, CD14, and MyD88 suggest that a MyD88-dependent signaling pathway may mediate the development of acquired immunity in cattle infested with Lone Star ticks. Additionally, increased expression for IL12, IFNgamma, and TNFalpha suggests that a Th1-type cell-mediated reaction may be activated, whereas increased expression of IL6, IL10, and IGHG1 supports the involvement of a Th2-type humoral-mediated response at tick bite-sites in cattle infested with at A. americanum. Regression analyses identified strong correlations between factors involved in pattern recognition in tick bite-site biopsies, including associations between TLR4 and IL1alpha, and between IL1alpha and IL1RN. In conclusion, this dissertation reports optimal methodology for gene expression studies in tick-infested cattle and provides preliminary data concerning the underlying mechanisms associated with the immune response in Lone Star tick-infested cattle.

Objetivo: El objetivo del presente trabajo fue determinar el efecto citoprotector y antisecretor del extracto acuoso de Solanum americanum Mill (hierba mora) en ratas con úlcera gástrica inducida y observar la presencia de reacciones adversas. Métodos: Se emplearon 72 ratas fueron divididas en grupos de 6. Para evaluar el efecto citoprotector, la úlcera fue inducida administrando indometacina 30mg/kg; para evaluar el efecto antisecretor se realizó la ligadura de píloro y para evaluar las reacciones adversas se administró el extracto durante dos meses; las dosis administradas de extracto fueron de 200mg/kg y 400mg/kg, las cuales fueron comparadas con el omeprazol a dosis de 10mg/kg. Resultados: El tratamiento con extracto de S. americanum Mill a dosis de 400mg/kg de peso, demostró efecto citoprotector, disminuyendo en 67% los indicadores de congestión, edema y hemorragia, inducidas con indometacina, sin embargo el omeprazol disminuyó en 67% los indicadores de congestión y hemorragia y en 100%, el indicador de edema. En ligadura de píloro, el extracto acuoso de S. americanum M. a dosis de 400mg/kg de peso, demostró efecto antisecretor disminuyendo el volumen de la secreción gástrica en un 66% y aumentando el pH en un 163%; comparado con omeprazol que disminuyó la secreción gástrica en un 83.6% e incrementó el pH en un 201.5%. En la determinación de efectos adversos, S. americanum M. demostró ser seguro a dosis de 400mg/kg de peso. Conclusión: En las condiciones experimentales, el extracto acuoso de S. americanum M. ha demostrado tener efecto antisecretor y citoprotector en ratas con inducción de úlcera gástrica, y con mínimos efectos adversos. / Aim: The aim of this study was to determine the cytoprotective and antisecretory effect of extract aqueous of Solanum americanum Mill (hierba mora) in rats with gastric ulcer induced and to observe the presence of adverse reactions. Methods: We used 72 rats were divided en groups of 6. For the cytoprotective effect, the ulcer was induced by administration of indomethacin 30mg/kg b.w.; the antisecretory effect by pylorus ligation and to evaluate the adverse reactions the extract was administered for two months, the doses of extract were 200mg / kg and 400mg/kg, which were compared with omeprazole at a dose of 10mg/kg. Results: Treatment with extract of S. americanum Mill at a dose of 400mg/kg b.w., showed cytoprotective effect, decreasing in 67% the indicators of congestion, edema and hemorrhage induced with indomethacin, however omeprazole decreased 67% the indicators of congestion and hemorrhage, and 100% the indicator of edema. In pylorus-ligated, the extract aqueous of S. americanum Mill a dose of 400mg/kg b.w., showed antisecretory effect, decreasing the volume of gastric secretion in 66% and increasing pH in 163%, and the omeprazole reduced the gastric acid secretion in 83.6% and increased the pH in 201.5%. In the determination of adverse effects, S. americanum Mill proved to be safe at doses of 400mg/kg b.w. Conclusion: In the experimentals conditions, the extract aqueous of S. americanum Mill possesses antisecretory and cytoprotective effect in rats with induced gastric ulcer, and with minimal side effects. / Tesis

A century ago, two large American mastodon Mammut americanum specimens from coastal South Carolina were mounted for display at Amherst College. Their robust build, broad and pentalophodont third molars, and well-developed mandibular tusks were noted as unusual. Here, these specimens are redescribed; three additional mastodon mandibles from the same region of South Carolina are also described. Though collection information on these specimens is sparse, they appear to span >150 ka in the Middle to Late Pleistocene, and probably include the first report of Mammut from the earliest-Rancholabrean Ten Mile Hill Formation. Some “unusual” features — moderately to extremely broad third molars, longitudinally-wrinkled enamel, very robust mandibles, large mandibular tusks — are present in most or all specimens, and may characterize regional mastodons. Description of these mastodons provides a useful starting point for more-thorough evaluation of the species in the Southeastern United States.

Relationships between jack pine dwarf mistletoe (Arceuthobium americanum Nutt. ex Engelm.) and Armillaria root disease (Armillaria ostoyae (Romagn.) Herink) were examined to determine how these two disease agents contribute to jack pine (Pinus banksiana Lamb.) decline and mortality in the Belair Provincial Forest, Manitoba, Canada. The incidence and extent of Armillaria root disease was strongly related to tree vigor. Dwarf mistletoe infection did not affect either the incidence of Armillaria or the mean percentage of root system colonization within vigorous, declining, and dead classes of trees. However, field observations and other analyses indicate that dwarf mistletoe was primary responsible for jack pine decline and mortality. In dwarf mistletoe mortality centers, Armillaria appeared to act opportunistically, extensively colonizing only the stressed trees. Analysis of distributions of percent Armillaria colonization revealed that rapid root system colonization occurred just prior to, or at the time of tree death.

Les relations entre l'activité de la source et l'activité du puits contrôlent en grande partie la croissance des plantes. Ces activités varient au cours du développement, mais aussi en réponse à des changements des conditions environnementales. Notre étude avait pour but d'identifier le rôle du métabolisme carboné dans la réponse de la croissance d'E. americanum à la modulation des activités de la source et du puits. Dans une première partie, l'activité du puits est modulée par la température de croissance. Aux fortes températures, l'activité du puits est plus élevée, alors que sa capacité est réduite. Ces effets, dus à la modulation du métabolisme du saccharose, mènent à une saturation précoce en amidon des bulbes à forte température. Par la suite, la baisse de la demande en carbone du puits induit un rétrocontrôle négatif de l'activité photosynthétique et finalement, la sénescence foliaire. À l'inverse, l'activité du puits à faible température est en rythme avec l'accroissement de la capacité, menant à une biomasse supérieure du bulbe en fin de croissance épigée. Dans une seconde partie, l'activité de la source est modulée en changeant la concentration en CO2 et en O3. Malgré la stimulation de la source sous fort CO2 et son inhibition sous fort O3, l'accumulation d'amidon et la biomasse du bulbe ne sont pas affectées. En effet, le surplus de carbone parvenant au puits est brûlé par la voie alternative de la respiration, celle-ci étant stimulée par l'activité de l'enzyme malique. La voie alternative de la respiration évite ainsi une saturation hâtive en amidon et éventuellement, une sénescence foliaire précoce. Dans une dernière partie, l'activité de la source est modulée par l'irradiance et la photopériode. L'accumulation d'amidon varie en fonction de la photopériode alors que l'irradiance n'a aucun effet. De plus, l'activité photosynthétique est inhibée très précocement sous longue photopériode. Cette inhibition semble due à un déséquilibre entre la quantité totale de carbone fixé par jour et son utilisation suite à son transfert au sein du bulbe. Nous pouvons donc conclure que les régulations du métabolisme carboné permettent d'ajuster l'activité du puits à la capacité de celui-ci chez l’E. americanum / Relationships between source and sink activities largely control the growth of plants. Both activities vary during development as well as in response to changes in environmental conditions. The aim of our study was to identify the role carbon metabolism plays in the response of E. americanum growth to changes in source and sink activities. Firstly, sink activity is modulated by changing growth temperature. Sink activity is higher at higher temperatures, whereas sink capacity is more restricted. These effects, due to the modulation of sucrose metabolism, lead to an earlier starch saturation of bulbs at higher temperature. Thereafter, the reduction in carbon sink demand induces a feedback inhibition of photosynthetic activity and finally, leaf senescence. In contrast, sink activity at low temperature is more in rhythm with the increasing sink capacity, leading to larger bulbs at the end of the epigeous growth season. Secondly, source activity is modulated by changing CO2 and O3 concentrations. Despite a stimulation of the source activity under high CO2 and its inhibition under high O3, neither plant growth nor starch accumulation was affected. Indeed, excess carbon translocated within the sink is burned by the alternative respiratory pathway. This pathway is stimulated by malic enzyme. Alternative respiratory pathway thus avoids an early starch saturation of the bulb and eventually, an early leaf senescence. Finally, source activity is also modulated by changing irradiance and photoperiod regimes. Starch accumulation changes in response to photoperiod but not to irradiance. Furthermore, photosynthetic activity is inhibited early in the season under long photoperiod. This inhibition seems due to an imbalance between the total amount of carbon fixed per day and its utilisation following translocation to the bulb. We can thus conclude that regulation of carbon metabolism allow to adjust sink activity to sink capacity in E. americanum.