Medical Students

The Mount Desert Island Biological Laboratory application is currently closed.

Mount Desert Island Biological Laboratory Application

The deadline to apply is Wednesday, January 22, 2025, at 2:00 p.m. EST.

Kidney TREKS, an initiative established by the American Society of Nephrology (ASN), is designed to foster interest in careers in nephrology and research through a week-long research course retreat and long-term mentorship program.

The Kidney TREKS MDIBL Program includes:

• Attending the Mount Desert Island Biological Laboratory's "Origins of Renal Physiology" course for students, June 7 – 14, 2025. Tuition, travel support to Maine, and room and board are paid by ASN.
• Becoming connected with a nephrology mentor who will interact with the participant over the course of medical school, residency, graduate school, or postdoctoral fellowship.
• Attending ASN Kidney Week within two years of participating in the TREKS program with travel support as a part of the ASN Kidney STARS Program.
• Receiving complimentary membership to ASN with access to website resources for trainees.

Eligibility

• a medical student who has completed at least one year of medical school,
• a graduate student pursuing a PhD,
• a postdoctoral fellow within their first year of training,
• or (new for this year) a first-year resident in an ACGME-accredited internal medicine, medicine-pediatric, or pediatric residency.

2. Must reside in North America.

3. This program is not for fellows already pursuing nephrology.

Program Schedule and Faculty

June 7 – 14, 2025

The course will be organized around several research modules that examine all aspects of kidney function. All students will be randomly assigned to three modules. Below are modules from previous years that we anticipate returning in 2025. New for 2025 is the Acid-Base Homeostasis module.

• Glomerular Filtration:.

  Leader: Hermann Haller, MD, | Mount Desert Island Biological Laboratory, Bar Harbor, ME.

  The glomerulus is located at the beginning of a nephron tubule. It comprises a network of capillaries inside Bowman's capsule that allows the formation of filtrate that then flows into the tubule. Podocytes and glomerular capillary endothelia plus the glomerular basement membrane that they create and maintain provide a filtration barrier that blocks entry into the tubules of blood cells and large molecules (proteins) while allowing salts, nutrients, and small waste molecules to be filtered. Many kidney diseases such as nephritic and nephrotic syndromes result from damage to the glomerulus. This module utilizes the zebrafish model system to study glomerular disease. Zebrafish glomeruli resemble those of mammals, and they have many experimental advantages including rapid embryonic development, transparency, a fully sequenced genome with many human orthologues, and the ability to manipulate gene expression using morpholinos. We will knock down the expression of specific proteins which are thought to play a role in glomerular function and determine the effects on glomerular function.
• Proximal Tubule:

  Leaders: Stewart Lecker, MD PhD, Kavita Mistry, MD | Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, Ken Ralto |UMass Memorial, Worcester MA, Anastasia Paulmann, MD, | Mount Desert Island Biological Laboratory.

  Proximal tubules make up the bulk of the kidney mass and are responsible for reabsorbing most of the plasma filtrate produced by the glomeruli. As such, their function requires large amounts of energy, and the cells are extremely metabolically active. The activity of the proximal tubule is also highly adaptable, increasing its absorptive capacity in conditions of volume depletion and its net acid production when necessary. The function of this tubular segment is tightly linked to mitochondrial ATP production required to fuel the Na+/K+ ATPase pump, which in turn creates the driving force for Na+ and HCO3- reabsorption, H+ production, and renal ammoniagenesis. The experiments in this module will explore how the mammalian kidney performs these tasks. One set of experiments will examine the urinary response to protein intake. We will measure changes in urinary acid (ammonium) and urea production to infer how glomerular and proximal tubular function might respond to these changes. In the second set of experiments, we will measure oxygen consumption in a mouse renal tubular preparation as a way of uncovering the metabolic activity of tubular cells. Using inhibitors and activators of the mitochondria, pumps (e.g., Na+/K+ ATPase), and ion transporters (e.g., Na+/glucose cotransporter, Na+/H+ exchanger) we will try and understand how energy (ATP) is utilized in the proximal tubule.
• Water and Salt Homeostasis:

  Leader: Mark Zeidel, MD | Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA.

  As Claude Bernard said in the 1800s, "the constancy of the internal milieu is the condition of a free and independent existence." The most fundamental form of homeostasis is the maintenance of a constant osmolality of body fluids. Derangements of osmotic homeostasis represent the most common and potentially lethal electrolyte disorders and often require emergent and expert treatment. In this module, we will perform balance studies in humans, measure water flow across intact toad bladders (a model of the human collecting duct) and aquaporin water channels, and monitor in cultured cells the trafficking of aquaporin 2 water channels in response to vasopressin. These studies will give trainees a comprehensive understanding of how humans and other organisms control their osmolality despite massive changes in water and salt intake.
• Secretory:

  Leaders: Patricio Silva, MD, Emeritus Professor, | Temple University, Philadelphia, PA and David Evans, PhD, Emeritus Professor, | University of Florida, Gainesville, FL.

  The secretion of ions across epithelia occurs in many different organs in the human body. Examples are the eye, ear, respiratory epithelia, gastrointestinal tract, liver, pancreas, kidney, and reproductive organs. Although the ions secreted and the intrinsic mechanisms that mediate secretion vary among each of these organs, the basic process is remarkably similar. Ions accompanied by water move across epithelial cells through transport proteins that allow them to cross the cellular lipid membrane. The energy that sustains this traffic is provided by the activity of Na+K+ATPase, the sodium pump, that by keeping the intracellular concentration of sodium low, maintains an electrochemical gradient for sodium directed into the cell. Sodium and accompanying ions move into the cell through co-transporters riding this gradient. This module uses a T84 cell line in an Ussing chamber system to demonstrate these ion secretion principles. Over the duration of the course, key pharmacological agents will be used to reveal the different transporters involved in the secretory process.
• Sodium Regulation in the Distal Nephron:

  Leader: Kelly Weixel PhD, | Washington and Jefferson University, Pittsburgh, PA.

  A major role of the distal nephron is to fine tune the renal ultrafiltrate by adjusting sodium, potassium and water content as well as balancing acid and base. About 5% of filtered sodium is reabsorbed in the collecting duct through active transport by the epithelial sodium channel (ENaC). ENaC is a tightly regulated channel via two mechanisms; first, insertion and removal from the apical membrane and secondly by the ability to open and close the channel. This module will use a heterologous expression system – oocytes from the Xenopus frog to allow expression of the three ENaC subunits. The large size of the oocyte and a trans-epithelial flow of sodium ions through the channel facilitates measurement by a two electrode voltage clamp electrophysiological apparatus. Experiments will consider the basic function of the channel, the effect of a number of different mutations on channel function, post translational processing of the channel and aspects related to its trafficking.
• Calcium Oxalate Stones and Drosophila:

  Leader: Michael Romero, PhD | Mayo Clinic, Rochester, MN.

  Drosophila melanogaster, the fruit fly, has been a vital genetic model organism for over a century. Few model organisms offer such ease of rearing, low cost, and genetic malleability paired with sophisticated eukaryotic physiology and behavior. In recent years it has been recognized that the Drosophila excretory organ, the Malpighian tubule (MT), represents an elegantly tractable yet complex model of solute transport via renal epithelia. This module will focus on the powerful vertical integration of this model system. We will explore whole animal physiology by demonstrating the formation of calcium-oxalate crystals in the MT, a model of mammalian calcium-oxalate nephrolithiasis. Next, we will explore the cellular and subcellular physiology of ion transport which underlies trans-epithelial oxalate movement through live-imaging of genetically encoded fluorescent pH-indicators. We will then consider the biophysical characterization of Drosophila water channels in a heterologous expression system (Xenopus laevis oocytes) and their contribution to stone formation. Finally, we will look at the contribution toward stone formation from uropathogenic Escherichia coli.
• Acid-Base Homeostasis:

  Leader Ian Thornell, PhD, | University of Iowa, IA.

  The acid-base status of extracellular fluid is highly regulated. The extracellular H+ ion concentration (pH) is maintained within a highly restricted range despite potential large loads of ingested alkali, increased metabolic production of acid or changes in partial pressure of CO2 (PCO2). The kidney adapts to these challenges by either rapidly modifying the reabsorption of filtered HCO3- and/or the quantity of net acid excreted. To modulate these transport parameters, the kidney varies the apical membrane expression and activity of proximal tubule NHE3 (the Na+/H+ exchanger), renal ammoniagenesis and the expression of a proton pump (H+-ATPase) in the apical membrane of the alpha-intercalated cells of the collecting duct. Experiments will consider how the kidney adapts to acid and base loading in the diet. Additionally, an immortalized cell line will be used to characterize some of the acid-base transport systems that these cells express by assessing the effects of ion substitution experiments and inhibitors on cell pH.

Click here for a sample program schedule.

Click here for a letter from a previous program participant describing her experience.

Program Housing

Please note that TREKS participants should be prepared to share housing with other program participants.

• Housing is assigned. On-campus housing is within walking distance of all campus facilities (Note: campus grounds include wooded terrain).
• Some accommodations will be in cottage-style facilities. Cottages sleep 4-5 with double and single occupancy. These accommodations include shared bathrooms, a kitchen, a living room, high-speed wireless internet, and parking.
• Other accommodations are dormitory style and also include shared bathrooms, common rooms, high-speed wireless internet, and parking.

Other Information

The course is run by Mark L. Zeidel, MD, FASN. This is a highly rated course that provides trainees with an opportunity to interact with the highest quality educators.

For questions or more information about the Kidney TREKS program, please contact ASN Leadership Development Manager Molly Rubin at mrubin@asn-online.org.