Skip Navigation
Regional News
Frog and flatfish, in stages of metamorphosis
Frog and flatfish, in stages of metamorphosis

Biologist passes along his fascination with metamorphosis

Listen to this story
Dr. Alexander Schreiber studies change--the metamorphosis of amphibians and flatfish. His St. Lawrence University biology lab teems with frogs and fish in various stages of development.

His enthusiasm for his subject sends him off campus to local grade schools. And at SLU, it attracts even English majors like our intern, Roger Miller. Schreiber told Roger he just never stopped being a kid.

Roger Miller is a senior at St. Lawrence University. He's worked as an intern in our news and web departments for the last couple of years. We'll miss him, and wish him well after graduation this weekend.

Hear this

Download audio

Share this


Explore this

Story location

News near this location

Video: Frog and flatfish metamorphosis (text continues below video)

“I basically took my child-like fascination with certain aspects of biology and maintained it through adulthood, so I’m still asking the same questions that I was asking when I was a kid.”

Asked if he just has fancier tools, Schreiber replies, “Oh no, toys. Toys!” Schreiber says. “That’s right, as long as you play with toys you do not grow old. That’s my hypothesis.”

“This is the lab. This is where the frogs hang out. There are no flatfish here, these are all frogs.”

There are nine water-filled buckets on the floor, each with a very large, pale-green amphibian. These are African Clawed Frogs or Xenopus Levus.

Schreiber  says, “This is our model organism that we work with and what we’ve been doing is feeding these frogs swordfish and this may seem like an odd thing to do, but swordfish are extremely high in mercury and we are trying to increase mercury content in these frogs to see what effects it has on the adults but more importantly what effects it has on the larvae that they produce.”

Schreiber and his students are testing the neurological effects of mercury by measuring how fast these little tadpoles can react and escape from a potential threat, like, say, a bigger fish or raccoon. While some tadpoles are the offspring of frogs fed a diet high in mercury, another batch of tadpoles to be tested were born from frogs raised on salmon, which contains far less mercury, but the same nutritional content.

“These particular species we can feed frog food… it’s essentially what you would feed to a dog, dog food, dog pellets, but a little bit smaller.”

On the other side of the lab there are tubs against the wall filled with tadpoles.

Schreiber  says, “And these are not just any tadpoles, these are transgenic tadpoles and what transgenic means is that we have inserted genes from another species into the genome of these tadpoles.”

These tadpoles have a gene only found in jellyfish known as Green Fluorescent Protein or GFP.” When you turn the lights off and shine an ultraviolet light on them, they actually glow green!

Schreiber  says, “Now, it’s one thing to make a tadpole glow in the dark because its fun and interesting and it looks cool, but what we’re really interested in is using this green fluorescent protein as a tag.”

Parts of the tadpole will only glow when cells are using this gene. This means that Dr. Schreiber can attach GFP to other genes to see what they’re doing and when during metamorphosis.

Schreiber and his students have also taken some incredible pictures and time-lapse videos of frogs and flat-fish undergoing metamorphosis—what normally takes days and months is condensed into seconds and minutes. In one video, the bony eye socket of a juvenile flatfish actually migrates around the head and comes to rest alongside the other eye.

“I’ve always wanted to figure out a way to convey my enthusiasm for how cool this process is and that’s when I became interested in basically photographing these creatures in such a way that I could present the changes of metamorphosis to a broader audience so they could gain some insight into the way I see these animals when I look at them under a microscope.”

Schreiber has been working with his frogs and flatfish for 14 years including the four he’s taught at St. Lawrence.  He also takes his science lessons on the road to local grade schools.

“You may think that this is maybe inaccessible to a 4th grader, but it is very easy to talk about genes and metamorphosis and how we can take genes from a jellyfish and put them into a frog and make it glow in the dark. You’d be amazed at what they can absorb because their minds are designed to take in this new information and, again, they have this inherent fascination with metamorphosis so it’s really fun to take the pictures that I have photographed of metamorphosis and let the pictures do the talking. It’s all about having fun.”

Scores of photos of these green and red, transgenic tadpoles and flatfish in various stages of metamorphosis, many taken by students,  are now on display in St. Lawrence University’s Brush Art Gallery.

Roger Miller is a senior at St. Lawrence University. He’s worked as an intern in our news and web departments for the last couple of years. We wish him well after graduation.

Visitor comments

on:

NCPR is supported by:

This is a Visitor-Supported website.