Beaver central place foraging : literature review, model and field test

The spatial distribution of tree cutting activity by beaver (Castor canadensis Kuhl) and tree availability were measured at two beaver colonies near Thunder Bay, Ontario. Beaver maximize the net rate of energy acquisition (e/t) when they minimize the distance travelled from the lodge, their central place, while obtaining a balanced diet. However, beaver must travel through two mediums to obtain terrestrial forage so minimum distance is a function of the relative costs of swimming and walking. A continuum of relative costs was used to generate two contrasting foraging models: 1) swimming equalled the cost of walking and the foraging path was a straight line from the lodge to a tree; 2) swimming was costless and the foraging path was the shortest distance from water to a tree. The models were compared for relative goodness of fit with the observed foraging pattern using chi-square and linear regression goodness of fit tests. The water costless model was the best fit model and empirically supported the implicit assumption of most workers that the pond is the effective central place. In practical terms 'water costless* was judged to be indistinguishable from a 5-10 times advantage for swimming over walking. Although experimental confirmation is required, this advantage was considered too large to be explained by energy or time savings and was therefore not an optimization of e/t. It was tentatively concluded that the pond should be viewed as a refuge from predators which probably constrain the relative availability of terrestrial forage to beaver. A test for optimal foraging, given the predation constraint, showed that beaver were maximizing e/t at Northbranch Pond. At Pinetop Pond, a relatively old site, beaver expanded their refuge to obtain patches of relatively high food quality. They could have realized higher e/t with perfect knowledge of their site, but apparently they maximized e/t with a patch use strategy that minimized search time. A review of beaver literature discussed optimization processes at four levels: evolution of body form and function, the individual lifespan, yearly, and seasonally. Arguments of particular interest were developed for dispersal (population regulation), central place, and the size-distance relationship

Constitutive Association of Tie1 and Tie2 with Endothelial Integrins is Functionally Modulated by Angiopoietin-1 and Fibronectin

Functional cross-talk between Tie2 and Integrin signaling pathways is essential to coordinate endothelial cell adhesion and migration in response to the extracellular matrix, yet the mechanisms behind this phenomenon are unclear. Here, we examine the possibility that receptor cross-talk is driven through uncharacterized Tie-integrin interactions on the endothelial surface. Using a live cell FRET-based proximity assay, we monitor Tie-integrin receptor recognition and demonstrate that both Tie1 and Tie2 readily associate with integrins α5ß1 and αVß3 through their respective ectodomains. Although not required, Tie2-integrin association is significantly enhanced in the presence of the extracellular component and integrin ligand fibronectin. In vitro binding assays with purified components reveal that Tie-integrin recognition is direct, and further demonstrate that the receptor binding domain of the Tie2 ligand Ang-1, but not the receptor binding domain of Ang-2, can independently associate with α5ß1 or αVß3. Finally, we reveal that cooperative Tie/integrin interactions selectively stimulate ERK/MAPK signaling in the presence of both Ang-1 and fibronectin, suggesting a molecular mechanism to sensitize Tie2 to extracellular matrix. We provide a mechanistic model highlighting the role of receptor localization and association in regulating distinct signaling cascades and in turn, the angiogenic switch

Compilation no.3

The 2024 Class of All Maine Women and members of the Retiree Council met on Saturday, February 10, 2024 to conduct the Living History Project. The project interviewed two retirees of the University to collect their experiences at the University of Maine. Members of All Maine Women took and submitted notes to Fogler Library Special Collections in addition to recording the interview

Report of a Curriculum Used in a Peer-Delivered Intervention to Reduce Obesity of Adolescents in Southern Appalachia and its Relationship to the National Health Education Standards

Adolescent obesity in Southern Appalachian is among the highest in the nation. Even though adolescent obesity is a major public health concern, effective interventions are limited. Team Up for Healthy Living is a cluster-randomized control trial developed to test the effectiveness of a cross-peer intervention with high school students focusing on healthy eating and physical activity. This instructional article describes the 8-week curriculum developed and utilized by Team Up for Healthy Living with an emphasis on the relationship to National Health Education Standards. This is important given the standards were created to promote and support health-enhancing behaviors for students all across America. Findings showed that this intervention adhered highly to the National Health Education Standards. It may be important for future school based obesity prevention efforts to consider using these standards as a framework to help meet national health education goals

Determining the Effects of Maternal Adiposity on Preterm Neonatal Microbiome and Short Chain Fatty Acid Profiles

The gut microbiota and its metabolites have vast impacts on the human digestive system, immune system, and health outcomes. Short chain volatile fatty acids (SCVFAs) present in feces can be representative of the interactions of the microbiota present in the gut. Low microbiota diversity in the human gut is highly associated with obesity and adverse health outcomes. Furthermore, the maternal microbiome has a direct impact on neonatal microbiota through various pathways such as environment, skin flora, breast milk composition, and vaginal secretions. This study is aimed to further understand the associations between various factors (maternal adiposity, gestational time, length of life, delivery mode, and race/ethnicity ) and neonatal microbiome and its metabolites, SCFA. Data (pre-pregnancy BMI, gestational time, length of life at time of sample collection, delivery mode, race/ethnicity, SCVFA profiles, fecal fermentation profiles, and 16s rRNA sequences, n=75) was obtained from 75 mother-infant dyads. Qiagen CLC Genomics Workbench was used to process 16s RNA data, generate quantitative and qualitative measures of alpha and beta diversity, and generate an analysis of the composition of microbiomes for differential abundances. Multiple metrics were analyzed for alpha and beta diversity and no significant differences were found for acetic acid (A), propionic acid (P), butyric acid (B), or APB combined. Shannon diversity index, a measure of Alpha diversity, showed no significant difference between groups in each subset. BMI differences were significant for no c-section vs. c-section and Black vs. White race/ethnicity. There were no significant differences found in PERMANOVA, a measure of beta diversity, or found in differential abundances among the groups