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Arceuthobium divaricatum is a species of dwarf mistletoe that parasitizes six species of pinyon pine (Pinus subsec. Cembroides). Previous phylogeographic research discovered a population of A. divaricatum in the Guadalupe Mountains of Texas that had significant sequence divergence in intergenic regions of chloroplast DNA compared to all other populations. In this study, conserved regions of nuclear intergenic DNA from the same Guadalupe Mountains population and its two neighboring populations were amplified using PCR and then sequenced. The DNA sequences were edited and aligned to determine if there was a significant amount of nuclear sequence divergence. There is 3.8% nuclear sequence divergence between the Guadalupe Mountain population and its two neighboring populations, which is more than the 3.5% nuclear sequence divergence in two recognized subspecies of Arceuthobium vaginatum obtained from GenBank. Based on genetic information the divergent population may warrant further investigation to determine whether it might be better classified as its own subspecies.
African brown house snakes (Boaedon fuliginosus) provide a unique opportunity to observe juvenile pheromone trailing behavior in a species of snake that does not use overwintering hibernacula or exhibit aggregation behavior. Using a standard Y-maze as a trailing behavioral assay, the presence and likelihood of captive juvenile B. fuliginosus to trail conspecifics was measured. Juveniles were assessed for trailing juvenile conspecifics as well as non-related adult female conspecifics. A binomial statistic determined if trailing behavior is significantly different than random probability. Juvenile B. fuliginosus did not exhibit significant trailing behavior in regards to other juvenile conspecifics (n = 15). However, trailing behavior was observed for juveniles trailing non-related adult females in 80% of trials (n = 15). Presence of juvenile pheromone trailing in this species may have other functions beyond hibernacula searching and/or conspecific aggregation.
We examined the dynamics of green sunfish (Lepomis cyanellus) in Gilmore Creek, a coldwater trout stream in southeastern Minnesota, over two time scales. On a historical scale, green sunfish occurred in the creek with other warmwater fishes after deforestation and poor farming practices in the late 1800s and early 1900s resulted in higher water temperatures and other habitat degradation. Reforestation and improved land management led to a restored trout fishery by the 1970s and 1980s. Since then, green sunfish have been known to invade the creek from downstream Boller Lake during high water events in late summer or early fall. After such an invasion event in 2010, catches of green sunfish declined exponentially over the subsequent months. Available evidence suggests that green sunfish have little predatory impact on brown trout because few sunfish remain in the creek by late fall when trout lay their eggs, and even fewer sunfish are present by spring when trout eggs hatch.
The effects of Brassica rapa stem color on the selection of host plants by Pieris rapae were investigated using choice tests between seedlings with reddish-purple, anthocyanin-containing stems and seedlings with light-green, anthocyaninless stems. The first landing response and the collective as well as the individual egg-laying behavior of P. rapae female butterflies to the reddish-purple-stemmed seedlings were comparable to the responses to the light-green-stemmed plants. These results demonstrate that stem anthocyanins do not play a significant role in host plant selection.
Native plant communities support a diverse biota of invertebrates, birds, and other wildlife, and are therefore essential to the health of ecosystems. Agriculture and urban development have eliminated most native plant communities through forest clearing and introduction of exotic, invasive plants. Prior to European settlement, bottomland hardwood forests prevailed along broad floodplains within the lower Mississippi alluvial valley. Dominant taxa included Taxodium distichum (L.) Rich. (bald cypress), Quercus spp. (oaks), Carya spp. (hickories), Fraxinus pennsylvanica (green ash), Liquidambar styraciflua (sweetgum), Celtis laevigata (sugarberry), Ulmus spp. (elms), and Nyssa spp. (gums). Much of this forested area, however, has been cleared and used for agricultural purposes or urban development. Bottomland hardwood forests, situated along the Mississippi River, are associated with the Mississippi Flyway, a bird migration route heavily utilized by migratory waterfowl, songbirds, and shorebirds for food, water, and shelter. In this preliminary study, woody plant species (trees and shrubs) occurring on the 134 hectare Delta State University campus (33°44.756′N, 90°44.026′W) were identified and documented. At present 46 families, 77 genera, and 125 species have been recognized. Only 66 species are native to the state of Mississippi. Only 41 species are native to the Mississippi Delta. We encourage the planting of more native woody plants representative of bottomland hardwood forests that will benefit migratory wildlife and enhance native habitat and food availability.
Stress has been shown to impact the rate of development in many species of vertebrates, including amphibians, reptiles, and mammals. We investigated how treatments of corticosterone, a glucocorticoid stress hormone, would affect the development and immune function of the Western Chorus Frog (Pseudacris triseriata) and the Southern Leopard Frog (Lithobates sphenocephalus). These two species exhibit different metamorphic rates, and we specifically chose these species as we wanted to determine if stress during development had a different effect on species with substantially different developmental periods. Tadpoles in the treatment group were given doses of corticosterone (0.5 μM in their water) and tadpoles in the control group were not dosed with corticosterone. Following three weeks of treatment, a blood sample was collected from each tadpole for use in a Candida albicans killing assay to test constitutive immunity. The findings suggest that Western Chorus Frog tadpoles and Southern Leopard Frog tadpoles differ significantly in their response to stress, from both a developmental and an immunological standpoint. Western Chorus Frog tadpoles treated with corticosterone developed significantly faster than control tadpoles and had significantly weaker immune responses to the C. albicans challenge. Conversely, there was no significant difference in development in Southern Leopard Frog tadpoles treated with corticosterone compared to controls; however, those given corticosterone had significantly stronger immune responses to the C. albicans challenge. Together, these findings suggest fundamental differences in larval amphibian response to stress that may be related to physiological and ecological restraints in each species.
Atrazine and chlorpyrifos are a commonly used herbicide and pesticide, respectively. Mammalian studies have found similar effects from these chemicals including reduced birth weight of offspring and reduced numbers of viable offspring. Additionally, invertebrate and fish studies have found synergistic toxicological effects. It was hypothesized that these chemicals would not individually have statistically significant effects but the combined group would experience effects on birth weight of pups and number of pups born as a result of synergistic effects. This study examined the effect of these two chemicals in Sprague Dawley rats at levels of 25mg/kg of body weight for atrazine and 5mg/kg for chlorpyrifos. Four groups were established: a control receiving corn oil, a group receiving only atrazine, a group receiving chlorpyrifos, and a group receiving both chemicals. Subjects were exposed for three weeks prior to impregnation and throughout term. No statistically significant differences were found among any of the groups in number of offspring per litter or average weight of pups. Future studies could increase the concentrations of these chemicals to examine effects at higher dosages; however, higher doses lose relevance to possible environmental exposure.
Due to the high frequency of post-surgical infection, antibacterial coated suture material has been developed and is suggested to reduce infection during healing. Triclosan is a common antibacterial that is now being incorporated into suture material. When the sutures are placed in the body, the triclosan is slowly released into the tissue over time. Recent studies show a potential for accumulation in fatty body tissues which would amplify the exposure to triclosan. Since exposure time to the drug plays a significant role in the magnitude of its results, the effects on tissue cultures should be investigated. The purpose of this study was to determine if triclosan inhibits tissue proliferation at supraphysiological doses to find out whether or not further study is required. Rat peritoneal tissue was excised from neonatal rats. It was hypothesized that triclosan would have a significantly negative effect on tissue proliferation. However, the results showed that even at high doses, triclosan had no effect on proliferation.
DiGeorge syndrome (DGS) is one of the most common genetic syndromes, resulting from random mutations in the 22q11.2 region of chromosome 22. The effects of DGS are highly variable and include craniofacial abnormalities, cardiac defects, immune deficiencies, cognitive impairment and psychiatric disorders. The molecular mechanisms underlying the manifestations of DGS are not completely understood. Identifying specific mutations and molecular pathways involved in DGS and the resulting phenotypic characteristics are areas of ongoing investigation. Many of the manifestations of DGS have been linked to deletion of the T-box transcription factor 1 (TBX1) gene, which plays a role in neural crest cell migration, pharyngeal arch (PA) development and formation of the pharyngeal pouches. TBX1 interacts with many molecular pathways leading to craniofacial defects and aberrant neural crest cell migration and survival. Many of the psychiatric and cognitive effects of DGS have been linked to mutations in genes such as DiGeorge critical region (DGCR6), Catechol-O-methyltransferase (COMT), Phosphatidylinositol 4-kinase alpha (PIK4CA) and zinc finger, DHHC-type containing 8 (ZDHHC8) that regulate neurotransmitters and neuronal metabolism. Understanding the genetic and molecular mechanisms underlying DGS can lead to more effective and targeted therapy for patients. In this review, current findings on the genetic aspects of DGS are summarized and future directions for research are addressed.