Constructing an Effective Annual Departmental Report

Departmental strategic needs are wide-ranging placing increased demands on chairs to broaden their roles. To meet growing strategic demands, chairs must systematize the gathering of pertinent analytics and information. This workshop identifies important items to include in annual departmental reviews and how to leverage data towards positive departmental change

Data-Informed Program Planning for Academic Chairs and Directors

Presenters and participants will engage in conversations related to data-informed decision making for academic departments and programs. Emerging strategies and best practices in data analysis will be employed to address critical questions related to cost efficiency, enrollment trends, and faculty load at the program level

Daisy Deane

https://digitalcommons.library.umaine.edu/mmb-vp/5322/thumbnail.jp

Competitive Interactions among Symbiotic Fungi of the Southern Pine Beetle

The southern pine beetle, a damaging pest of conifers, is intimately linked to three symbiotic fungi. Two fungi, Ceratocystiopsis ranaculosus and Entomocorticium sp. A, are transported within specialized structures (mycangia) in the beetle exoskeleton and are mutualists of the beetle. A third fungus, Ophiostoma minus, is transported externally on the beetle exoskeleton (phoretically) and is an antagonist of the beetle. This study examined competitive interactions among these three fungi. The results of de Wit replacement series and primary and secondary resource capture assays with these fungi provide strong evidence for differential competition between the phoretic and mycangial fungi. O. minus was the most able to capture both uncolonized and colonized resources. Entomocorticium sp. A and C. ranaculosus, although equal to one another in compet- itive abilities, differed in their ability to compete with O. minus. Entomocorticium sp. A was able to maintain space free of O. minus to a much greater degree than was C. ranaculosus. The outcome of such competitive interactions may have significant impacts on the biology of this ecologically and economically important beetle

State-independent Block of BK Channels by an Intracellular Quaternary Ammonium

Intracellular blockade by quaternary ammonium (QA) molecules of many potassium channels is state dependent, where the requirement for channel opening is evidenced by a time-dependent component of block in the macroscopic record. Whether this is the case for Ca2+- and voltage-activated potassium (BK) channels, however, remains unclear. Previous work (Li, W., and R.W. Aldrich. 2004. J. Gen. Physiol. 124:43–57) tentatively proposed a state-dependent, trapping model, but left open the possibility of state-independent block. Here, we found BK channel blockade by a novel QA derivative, bbTBA, was time dependent, raising the possibility of state-dependent, open channel block. Alternatively, the observed voltage dependence of block could be sufficient to explain time-dependent block. We have used steady-state and kinetic measurements of bbTBA blockade in order to discriminate between these two possibilities. bbTBA did not significantly slow deactivation kinetics at potentials between −200 and −100 mV, suggesting that channels can close unhindered by bound bbTBA. We further find no evidence that bbTBA is trapped inside BK channels after closing. Measurements of steady state fractional block at +40 mV revealed a 1.3-fold change in apparent affinity for a 33-fold change in Po, in striking contrast to the 31-fold change predicted by state-dependent block. Finally, the appearance of a third kinetic component of bbTBA blockade at high concentrations is incompatible with state-dependent block. Our results suggest that access of intracellular bbTBA to the BK channel cavity is not strictly gated by channel opening and closing, and imply that the permeation gate for BK channels may not be intracellular

Nitrogen Budgets of Phloem-Feeding Bark Beetles with and without Symbiotic Fungi

The nitrogen content of plant tissue is low relative to that of herbivores; as a consequence, dietary N can limit the growth and reproduction of herbivores and select for attributes that increase N acquisition. Bark beetles face a particularly severe challenge because the phloem that they consume is very low in nitrogen and phosphorus relative to their requirements. We quantified variation in the phloem concentrations of N and P in the host tree, Pinus taeda, and evaluated the following hypotheses regarding the role of symbiotic fungi in nutrient budgets of the herbivore Dendroctonus frontalis: D. frontalis experience variation in phloem nutrient concentrations across several spatial scales (H1); mycangial fungi enhance the diet of D. frontalis larvae by contributing to the acquisition of N and P (H2); Ophiostoma minus, an apparently antagonistic fungal symbiont, hinders D. frontalis larvae because it does not enhance nutrient concentrations of the phloem as much as mycangial fungi do (H3); and larvae of bark beetle species that lack mycangial fungi must consume more phloem to accomplish the same growth as larvae of D. frontalis (H4). In addition, we developed a general model for the N budgets of herbivorous insects that identifies the possible combinations of dietary and physiological parameters that can allow developmental success on low‐nutrient diets. Spatial variation in phloem N was mostly at the level of trees within sites (a scale of meters) while P mostly varied among sites (a scale of kilometers). Trees with higher N content produced larger D. frontalis adults. Prior to infestation by beetles, phloem nutrient concentrations were very uniform within trees and very low relative to that of the bark beetles (N and P concentrations of D. frontalis adults were 28 and 8 times greater, respectively). During infestation, phloem nutrient concentrations increased overall and became highly variable within trees. Nitrogen concentrations increased from 0.40 ± 0.01% (mean ± 1 se) in uninfested phloem to 0.86 ± 0.03% in the phloem surrounding successfully developing D. frontalis larvae, which are typically associated with one or two species of mutualistic mycangial fungi. Nitrogen concentrations were intermediate in other microhabitats within infested trees, including regions with no adult colonization, with failed larval development, or colonized by the antagonistic bluestain fungus O. minus. We parameterized a general nutrient‐budget model for D. frontalis and a sympatric non‐mycangial bark beetle, Ips grandicollis, which indicated that (1) mycangial fungi provide their benefits by concentrating dietary N for larvae; (2) O. minus may exert its antagonistic effects on D. frontalis larvae by failing to concentrate dietary N as much as mycangial fungi do; (3) non‐mycangial bark beetles meet their N budgets through high consumption of unaltered, low‐N phloem; and (4) larvae should easily meet their P requirements with any combination of consumption rate and development time that allows them to meet their N requirements. Alternative strategies for N acquisition may have general consequences for the population dynamics and community interactions of bark beetles

Teaching the Logistic Growth Difference Equation Using Spreadsheets

The logistic growth difference equation is often used in biology to model population growth. The terms that satisfy the difference equation have many remarkable mathematical properties such as exhibiting chaotic behavior. Using spreadsheet modeling tools, the properties of logistic growth can be investigated by students in a user friendly environment. Students will learn about useful computational and modeling tools, while also learning about a new area of mathematics that has fascinated many (e.g. James Gleick’s Chaos: Making a New Science is a national best seller). Moreover, the model has many real world applications in biology. Unfortunately, many mathematics and computer science students do not see the logistic growth model because it does not appear in the standard set of required courses. In this paper we describe a how to implement the logistic growth model, and describe related applications and student exercises

The d subunit plays a central role in human vacuolar H+-ATPases

The multi-subunit vacuolar-type H+-ATPase consists of a V1 domain (A–H subunits) catalyzing ATP hydrolysis and a V0 domain (a, c, c′, c″, d, e) responsible for H+ translocation. The mammalian V0 d subunit is one of the least-well characterized, and its function and position within the pump are still unclear. It has two different forms encoded by separate genes, d1 being ubiquitous while d2 is predominantly expressed at the cell surface in kidney and osteoclast. To determine whether it forms part of the pump’s central stalk as suggested by bacterial A-ATPase studies, or is peripheral as hypothesized from a yeast model, we investigated both human d subunit isoforms. In silico structural modelling demonstrated that human d1 and d2 are structural orthologues of bacterial subunit C, despite poor sequence identity. Expression studies of d1 and d2 showed that each can pull down the central stalk’s D and F subunits from human kidney membrane, and in vitro studies using D and F further showed that the interactions between these proteins and the d subunit is direct. These data indicate that the d subunit in man is centrally located within the pump and is thus important in its rotary mechanism