Summer 2009

Biological Science Research

Bacterial biochemistry and physiology

Mary M. Allen

The overall goal of the research in my laboratory is to understand the relationship between environmental changes and stress and the biochemistry of bacterial cells. A number of projects, all underway in this laboratory, are available for student participation. Examples of projects are given below:

A. Effect of acidic pH on cyanobacteria. Cyanobacteria typically grow in alkaline waters, but lakes are becoming more acidic due to air pollution. We are trying to determine how cyanobacteria raise the pH of their environment to cope with this stress using NMR spectroscopy (in collaboration with Prof. Nancy Kolodny, Chemistry Department) to determine sodium and proton transfer through the cell membranes. We are also looking at the effect of acid stress on protein synthesis, cell growth and specific enzymes, utilizing 2D gel electrophoresis and proteomics as well as growth and biochemical analyses.

B. Cyanobacterial uptake of lead from the environment. Experiments are underway using cyanobacteria imbedded in calcium alginate beads to remove lead from water. Preliminary studies imbedding the cyanobacterium Synechocystis sp. strain PCC 6803 within beads suggest enhanced lead removal using the microorganism (in collaboration with Prof. Nolan Flynn, Chemistry Department).

C. Biofilm capability of cyanobacteria. We have observed biofilm formation in acid-stressed cells. Experiments are underway to determine how and when biofilms may form, to observe pili by electron microscopy, and to observe protein differences by proteomics.

Behavioral neurobiology

Joanne Berger-Sweeney

My laboratory focuses on the neurobiology of cognitive development and developmental disorders. How does the brain become wired during development to evince complex cognitive behavioral patterns in adulthood? How is normal development of cerebral cortex derailed in developmental disorders that result in mental retardation? In the last several years, we have been using mouse models of Rett Syndrome and Down Syndrome, two developmental disorders that in humans are associated with brain pathologies and mental retardation, to explore the relationship between abnormal brain structure and behavioral function. Using a combination of techniques from behavior to anatomy to MRI, we examine the timing of the development of the cerebral cortex as well as the development of locomotor, social and cognitive behaviors in normal and mutant mice. We also examine therapeutic interventions that may attenuate some of the behavioral deficits in these developmental disorders.

Evolution of modular design in vertebrates

Emily Buchholtz

My recent work is at the interface of vertebrate paleontology and developmental biology. I study the developmental constraints that affect the course of vertebral column reorganization when taxa undergo dramatic evolutionary transitions. These transitions often occur when lineages enter new environments, such as the secondary invasion of aquatic environments by terrestrial ancestors of ichthyosaurs, whales and seacows.

This summer, students will have the opportunity to contribute to these ongoing projects:

1) What are the historical and phylogenetic contexts of developmental innovations in the evolutionary diversification of the mammalian vertebral column? What do the type, frequency, and location of these innovations tell us about developmental constraints on the columnÕs adaptation? What is the modular hierarchy of the column in general, and of the sacral series in particular?

2) What developmental pathways have allowed exceptional genera to escape the cervical constraint? What are the postcervical consequences of escape and what do they reveal about the origin of the constraint? Recent studies of the morphological disruptions that accompany nontraditional cervical anatomy in sloths will be expanded by an intraspecific analysis of the pygmy right whale, Caperea marginata.

3) What was the functional route by which locomotion in early whales moved from the hind limbs to the axial skeleton? Can we interpret the fragmentary remains of transitional Eocene whales based on the soft and body caudal anatomy of living semiaquatic mammals?

Physiological ecology; cardiac electrophysiology

John Cameron

My research focuses on the cardiovascular physiology of ectothermic animals; in particular, I am interested in the ionic mechanisms that promote tolerance of depleted oxygen and low temperature conditions in vertebrates. Many aquatic vertebrates can withstand prolonged exposure to environmental conditions of cold or low oxygen that would prove lethal to mammals or to other, less tolerant, aquatic species. One area of difference between tolerant species and those sensitive to hypoxia and hypothermia is thought to lie at the level of specific ion channels in the cell membranes of essential organs. Tolerant tissues might respond to prolonged metabolic stress with a reduction in the density and/or rate of activation of such channels, thus reducing membrane permeability and compensating for decreased ATP-dependent ion pumping capacity in the face of hypoxic or cold environments.

Recently we have been using standard intracellular and patch-clamp recording techniques to monitor the activity of ATP-sensitive K+ (KATP) channels in cardiac muscle from the anoxia-tolerant goldfish (Carassius). Although the KATP channel is present at very high densities in the heart muscle of all vertebrates, its function is completely unknown. In mammalian tissues, a consensus is emerging to the effect that KATP currents serve a protective function, being activated as oxygen levels fall to maintain ionic homeostasis. Our overall goal is to clarify the role of this channel in aquatic animals that may actually experience periods of environmental hypoxia/anoxia.

Power and efficiency in animal locomotion

David Ellerby

Locomotion occupies a significant proportion of an animals daily activity pattern and the high rate of energy expenditure involved means that few aspects of an animals physiology, ecology and behavior are unaffected by its demands. Studies of animal locomotion tend to fall into two categories: those that focus on externally measurable parameters such as oxygen consumption and force generation; and those that measure the characteristics of internal systems such as muscle and tendon. A major aim of research in my lab is to integrate these different approaches at a number of levels, and determine the effectiveness and efficiency of locomotory systems. Initial work will use fish locomotion as a model system.

Botany and ecology in the campus Botanic Gardens

Kristina Jones and Alden Griffith

The Alexandra Botanic Garden, H.H. Hunnewell Arboretum, Margaret Ferguson Greenhouses, and Creighton Educational Garden are fabulous resources for research right on campus. Kristina is the director of the botanic gardens as well as faculty, with primary expertise in plant-animal interactions, and particular interest in how pollination and/or herbivory influences the distribution and abundance of plants, especially rare ones. A specific topic of interest within that is phenology, the timing of important life cycle events such as flowering and leafing out, and the extent to which insect pollinators and herbivores adjust to shifting plant phenology with climate change. With her administrative responsibilities, Kristina would prefer to co-advise summer research students with plant ecologists Alden Griffith and/or Katie Griffith (Visiting Scholar). Alden, the current Botany Fellow at Wellesley, is able to advise summer research students full-time as well as collaboratively.

Alden is starting up a research project examining closely-related native vs. nonnative species, and he is also interested in looking at plant-plant facilitation through pollinators. He is also planning to continue a long-term research project on Wellesley's forest patches that was initiated by students 10 years ago. Katie will be initiating a phenology study aimed at understanding the effects of global climate change on plant species. She will also be working on native plant restoration and invasive plant eradication in the Maple Swamp on campus. All of these topics are well suited for student research projects.

Another current research interest of Kristina’s that lends itself to student projects is the green roof planted with native species on the water treatment vault at the edge of the arboretum. It was planted in 2006 with 28 native plant species and is developing into an interesting community, with some species barely able to tolerate the difficult environmental conditions and others thriving and spreading. Also of interest is the suitability of this unique habitat for native insects.

Ecological significance and mechanisms of chloroplast movement

Martina Königer

The goal of my research is to understand the dynamics and the underlying mechanisms of chloroplast movement in plants. Chloroplasts alter their position within a cell in response to changes in light intensity in order to maximize light interception at low light and to avoid damage from high light. Changes in blue light intensity are detected by phototropin receptors and through a complicated signaling pathway induce changes in the arrangement of actin cables along which the chloroplasts move to a new position within the cell. Past research in our lab on a variety of Arabidopsis thaliana mutants has shown that plants with reduced chloroplast numbers and increased sizes exhibit a greatly reduced ability for chloroplast movement and thus limited possibilities for optimization of light interception at both low and high light. We are currently testing whether chloroplast movement and high light stress tolerance are similarly affected in plant species which vary naturally in chloroplast number and size. While most plant species have many, small chloroplasts within their cells, the numbers and sizes can vary significantly. For example, wild type Arabidopsis thaliana plants have 80-100 chloroplasts per cell, while Theobroma cacao (chocolate tree) plants have only 2 chloroplasts per cell. We are using techniques such as light transmission measurements, confocal microscopy, chlorophyll a fluorescence to answer these questions. We are also employing a variety of molecular techniques to address questions about the mechanisms that allow for chloroplast movement.

Organizing worker labor in honey bee colonies

Heather Mattila

Social insects form spectacular societies that are characterized by incredible levels of cooperation and striking division of labor. Each colony has a queen that spends most of her life laying eggs, which give rise to thousands of sterile daughters—the workers—who perform all of the tasks that keep the colony healthy and productive. Without a leader or specific instructions, workers seem to “know” what to do to contribute to the collective organization of their colony. How is this organization generated? My research focuses on the mechanisms that produce efficient, cohesive colonies, using honey bees as a model. We will complete three projects this summer that are related to this idea:

1) Honey bee queens mate with an unusually high number of males compared to queens of other social insect groups. As a result, each honey bee queen creates a colony that is filled with numerous families of half-sisters. My previous research has shown that this injection of genetic diversity into the work force results in a dramatic increase in colony productivity. One benefit that promiscuous queens confer to their colonies is the emergence of an enhanced foraging effort, including higher foraging rates and more waggle-dance communication among foragers. We will do an experiment that tests the effects of social environment (genetically diverse vs. genetically uniform) on the dancing behavior of worker honey bees.

2) One way that honey bee colonies reproduce is by colony fission, where half of the workers leave home with their queen to start a new nest some distance away. Presently, we have no idea how the departing workers and queen can fly through the air as a big, swirling swarm without become disorganized and decentralized, especially considering that almost none of the workers know where they are supposed to go. We will conduct studies to establish whether queens and/or workers produce pheromones that keep the swarm cohesive as it travels from the parental nest to a new nest site over the course of several days. We will also determine whether there are differences in gene expression between workers that stay in the original nest and those that leave with the swarm. This project with be completed with collaborators from Penn State University.

3) Can a honey bee colony have a “personality” that makes it more successful than its neighbors? We will determine how subfamilies of workers contribute to colony phenotype and whether this phenotype can be linked to aspects of fitness. This project will be completed with collaborators from Cornell University.

 

In addition to intensive field studies and video analysis of animal behavior, projects may offer students the opportunity to learn molecular techniques including DNA extraction, PCR, genotyping, pheromone capture and identification, and DNA microarray. All projects involve hands-on work with live honey bees, so students will also learn the craft of hive management and gentle beekeeping.