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How marmoset monkeys (Callithrix jacchus) cope with stability challenges during arboreal locomotion03/11/2015For arboreal mammals, problems of stability increase as branches become smaller and more compliant (i.e., move more under the animal’s weight). Changing the size and compliancy of a substrate should cause arboreal mammals to change their gait to facilitate balance. We tested this by having two marmosets (Callithrix jacchus) cross differently sized stable and compliant arboreal supports (5cm, 2.5cm, and 1.25cm in diameter). We filmed the marmosets with four high-speed cameras, testing how they would change their gait in order to maximize stability on thin and unsteady branches. Overall, the marmosets put more limbs on the substrate and for longer periods of time when substrate diameter decreased and when the substrate was compliant. Specifically, duty factors (the percent of time that a limb contacts the support during a stride) increased when the substrate size decreased. There was also a difference in duty factor between the stable and compliant substrates, such that the duty factor increased when the marmosets were on the compliant substrate. The average number of supporting limbs contacting the substrate at any one time also increased when the size of the substrate decreased and when the substrate became compliant. These findings show that marmosets respond to variation in substrate size and substrate compliancy in similar ways, in both cases increasing the average number of limb contacts and the duration of limb contact on a substrate in order to maintain stability. |
Fibroblast Growth Factor 8 Hypomorphy Does Not Affect Astrocyte Arborization Complexity in the Corpus Callosum of Adult Mice03/11/2015Fibroblast growth factor 8 (FGF8) has an array of functions in relation to a developing organism. Previous studies examined the role of FGF8 and its involvement with the formation of the corpus callosum in Fgf8 hypomorphic mice. Astrocytic glial cells are critical for the interhemispheric crossing of callosal fibers, and thus the formation of the corpus callosum. Using GFAP immunohistochemistry (IHC), we showed that midline astrocyte cell number was significantly reduced in heterozygous (+/neo) and homozygous (neo/neo) Fgf8 hypomorphic as compared to wildtype (WT) mice. These results suggest FGF8 signaling is critical for late gestational astrocyte cell development, possibly by acting on the progenitor cells that are destined to become astrocytes. Recently, it was shown that FGF8 increased astrocyte arborization complexity in cell culture (Kang et al., 2014). These findings led us to ask whether FGF8 also affected GFAP immunoreactive astrocyte arborization complexities in the corpus callosum of adult WT and Fgf8+/neo mouse brains using a computerized Sholl analysis. Our results showed, that unlike astrocytes in cell culture, corpus callosal astrocytes do not differ in complexity between WT and Fgf8+/neo adult mice. Currently, we are designing experiments that are designed to elucidate the incongruence between the in vitro and in vivo data. Indeed, cell culture astrocytes are derived from late embryonic animals. Therefore, instead of studying astrocyte arborization in adult, we will use newborn Fgf8 hypomorphic mice. Furthermore, we will study whether FGF8 signaling deficits affect the development of other glial cell types, such as oligodendrocytes and microglia using the IHC markers Olig2 and IBA-1. Future studies will address if FGF8-dependent disruption of midline glial cells development have functional consequences on the ability of midline glial cells to guide extending callosal fibers. |
Evaluating Stereoscopic Effects with EEG of Memory Formation and Regional Brain Activity03/11/2015A current line of research is focusing on the processes of spatial learning. Previous studies have indicated that students have trouble learning concepts which have a spatial component to them. Topics such as molecular geometry within the field of chemistry are notably difficult. Recent research has suggested that stereoscopic presentation of these objects may promote better learning. To understand the processes which contribute to spatial learning a neurophysiological approach is necessary. Therefore, in order to investigate the effectiveness of stereoscopic presentation and the neural correlates of it, an Electroencephalograph (EEG) was used. Participants were fitted with an EEG cap and had electrical scalp activity recorded using Brain Vision software. Participants were presented with images in both 3-D and 2-D of the organic molecule Hemoglobin. During the tasks the molecule rotated across three different planes, changed colors, and changed focal distance. The data collected was then analyzed using EEGLAB for MATLAB. Individual components associated with visual processing (visual cortex), executive processing (pre-frontal cortex), and memory (hippocampus) were identified using an Independent Components Analysis (ICA) and dipole modeling. The brainwave activity in these components were recorded and the components were correlated with one another. Preliminary data collected indicated an increased amount of activation in the visual cortex for 3-D processing as compared with its 2-D counterpart. The goal of these findings is to identify areas of the brain associated with spatial learning through stereoscopic presentation and to identify the optimal conditions for learning various spatial objects and molecules. |
Does sex, age, or species drive gut microbial community similarities between captive lorikeets?03/11/2015Gut microbial communities are known to be associated with immune defense. Changes to this microbial ecosystem can have negative effects on animal health. The Cleveland Metroparks Zoo has recently experienced an abnormally high mortality rate in their captive lorikeet colony, particularly in their younger animals. We hypothesized that lorikeet health may be associated with differences in gut microbial communities. We predicted that differences in gut microbiota between animals may be correlated with particular individual traits including bird age, sex, and species. Amplifying the 16S rRNA gene region of bacterial DNA and using a fragment analysis technique, we assessed gut microbial community structure across 34 birds. Analysis revealed two distinct groupings of similarly structured gut microbial communities across our samples; however, bird sex, age or species did not correlate with these groupings. In future laboratory studies, we will examine whether these two distinct groupings are driven by known deleterious microbes. |
Developmental allometry of the effective mechanical advantage in eastern cottontail rabbits (Sylvilagus floridanus)03/11/2015Juvenile mammals must often compete in the same ecological niche as adults, despite smaller absolute body size and muscle force capacity. However, because limb joints operate as levers, greater muscle mechanical advantage (i.e., ‘leverage’) in juveniles may permit greater force production despite these disadvantages. Previous research on mammals has shown that bony proxies for extensor muscle leverage are greater early in development and decrease throughout growth. However, no previous study of mammalian musculoskeletal development has collected the locomotor data needed to examine changes in actual (i.e., “effective”) mechanical advantage. We used high-speed videography and force plate measurements, combined with anatomical data on muscle lever arm lengths, to calculate effective mechanical advantage (EMA), a measure of limb muscle leverage, exploring the relationship between body size (proxy for age) and EMA. We predicted that if rabbits maintain proportionality during growth, then the length variables that determine muscle leverage should scale to the cube root of overall volume, and therefore the cube root of overall body mass (i.e., Mb0.33). However, we found that muscle lever arms scaled to Mb0.27, whereas the lever arms of the loading forces that the limb muscles had to resist scaled to Mb0.45. Therefore EMA, as the quotient of these two measures, scaled to Mb-0.18, such that muscle leverage decreased by 36% over the course of rabbit growth. Greater leverage early in life may permit young rabbits to attain adult-like levels of locomotor performance, despite smaller size and reduced muscle mass. |
Circadian Analysis on Human Population Entrainment: Inferences from the Power Grid03/11/2015Few, if any studies have focused on the daily rhythmic nature of modern industrialized populations. The present study involved actigraphic analyses of continuously streaming electrical load data from a human subject pool of approximately 43 million primarily residential users in the U.S. Pacific Northwest as a reflection of daily household activity. Rhythm analyses reveal striking seasonal and intra-week differences in human activity patterns, largely devoid of manufacturing and automated load interference. Length of the diurnal activity period (alpha) is longer during the spring than the summer (16.64 h versus 15.98 h, respectively; p < 0.01). As expected, significantly more activity occurs in the solar dark phase during the winter than during the summer (6.29 h versus 2.03 h, respectively; p < 0.01). Interestingly, throughout the year a “weekend effect” is evident, where morning activity onset occurs approximately 1 h later during the weekend than during the work week (5:54 am versus 6:52 am, respectively; p < 0.01). This indicates a general phase-delaying response to the absence of job-related or other weekday morning arousal cues, substantiating a preference or need to sleep longer on weekends. Finally, a shift in onset time can be seen during the transition to Daylight Saving Time, but not the transition back to Standard Time. The use of grid power load as a means for human actimetry assessment thus offers new insights into the collective diurnal activity patterns of large human populations. |
Beta Synemin is a Dual AKAP03/11/2015b-Synemin is a cytoskeletal that also functions to targets PKA to specific subcellular locations, thus it also functions as an A-kinase anchoring protein (AKAP). We have recently confirmed that b-synemin is capable of binding both PKA type I and PKA type II using yeast two-hybrid, FACS-FRET, and co-immunoprecipitation analysis, which therefore classifies it as a dual AKAP. Most interestingly, our co-immunoprecipitation data also suggests that the binding of PKA type I to b-synemin only occurs only upon stimulation of the b-adrenergic pathway. Currently we are carrying out co-immunoprecipitation studies to determine the binding status of PKA type II and the catalytic subunit of PKA under both basal and stimulated conditions. These data are exciting because they suggest temporal compartmentalization of PKA type I and II at a single subcellular location, b-synemin. |