Scientists reveal new and improved genome sequence of Daphnia pulex

May 05, 2017

For many, experience with Daphnia, commonly known as water fleas, ends in high school. The organism is often used for science experiments exploring water toxicity, because of its sensitivity to environmental factors. But the tiny, transparent microcrustaceans have been studied intensively for more than 150 years, and new research published and featured on the cover of the journal G3 reveals scientists can now take a closer look at its genome.

Researchers have completed a new and improved genome sequence of Daphnia pulex (D. pulex), providing a clearer roadmap of the organism's genome so they can identify the genes and pathways that make this organism so successful in freshwater ecosystems.

Populations of Daphnia, barely visible to the naked eye, can be found in virtually every standing body of water on the planet, including Antarctica. They evolve quickly and are masters of responding to the conditions in their environment. Sensing the chemical cues of nearby predators, some species of Daphnia develop elaborate defensive structures such as spines and helmets that make them harder to eat. While scientists have gained a thorough understanding of what these tiny water fleas do to adapt to varying conditions, they don't yet know how they do it.

"That's why a system like this is so powerful," said Michael E. Pfrender, director of the Genomics & Bioinformatics Core Facility and associate professor in the Department of Biological Sciences and the Environmental Change Initiative at the University of Notre Dame. "We need this genomic infrastructure to add to the ecological context we already have to gain a better understanding of how Daphnia adapt. Because we have an improved genome sequence, we can get a more accurate catalog of genes and when thinking about response to the environment and chemical cues, it's the turning on and off of genes and pathways that's important. The picture is much more complete than it was before."

Calling it the "Portland Arch" genome after the Indiana Nature Preserve where the Daphnia was collected, the new assembly comes six years after the first sequence of D. pulex in 2011. The current study describes how scientists used the latest technology as part of a thorough and methodical process the result of which led to the identification of 18,440 genes.

D. pulex plays a vital role in Earth's ecology. Feeding off of algae and phytoplankton in standing freshwaters, they are the primary grazer in those environments, the "cows of lakes," said Pfrender. They're also primary forage, transferring all of that energy to the fish that eat them. By understanding how species of Daphnia respond to toxic elements like industrial contaminants, toxic algae blooms or thermal stress, scientists can look at how environmental changes caused by agriculture and road runoff or warming temperatures and climate change could impact populations in lakes, rivers and standing bodies of water.

"What happens to this vital part of the ecosystem when conditions change very rapidly? What genes allow some populations to cope with these changes while others fail?" Pfrender said. "That's what we want to find out. This genome sequence provides the toolkit."
-end-
Co-authors of the study include Pfrender, Jacqueline Lopez and Brent Harker of the Notre Dame Genomics and Bioinformatics Core Facility; Zhiqiang Ye, Ken Spitze, Xiaoqian Jiang, Matthew S. Ackerman and Michael Lynch at the Department of Biology at Indiana University; Sen Xu at the Department of Biology at Indiana University and the University of Texas at Arlington; Jana Asselman, Laboratory for Environmental Toxicology at Ghent University; R. Taylor Raborn at the Department of Biology and School of Informatics and Computing at Indiana University; and W. Kelley Thomas and Jordan Ramsdell at the Hubbard Center for Genome Studies at the University of New Hampshire.

The study was funded through a grant from the National Institutes of Health to Michael Lynch at Indiana University, Bloomington and Notre Dame Research.

University of Notre Dame

Related Climate Change Articles from Brightsurf:

Are climate scientists being too cautious when linking extreme weather to climate change?
Climate science has focused on avoiding false alarms when linking extreme events to climate change.

Mysterious climate change
New research findings underline the crucial role that sea ice throughout the Southern Ocean played for atmospheric CO2 in times of rapid climate change in the past.

Mapping the path of climate change
Predicting a major transition, such as climate change, is extremely difficult, but the probabilistic framework developed by the authors is the first step in identifying the path between a shift in two environmental states.

Small change for climate change: Time to increase research funding to save the world
A new study shows that there is a huge disproportion in the level of funding for social science research into the greatest challenge in combating global warming -- how to get individuals and societies to overcome ingrained human habits to make the changes necessary to mitigate climate change.

Sub-national 'climate clubs' could offer key to combating climate change
'Climate clubs' offering membership for sub-national states, in addition to just countries, could speed up progress towards a globally harmonized climate change policy, which in turn offers a way to achieve stronger climate policies in all countries.

Review of Chinese atmospheric science research over the past 70 years: Climate and climate change
Over the past 70 years since the foundation of the People's Republic of China, Chinese scientists have made great contributions to various fields in the research of atmospheric sciences, which attracted worldwide attention.

A CERN for climate change
In a Perspective article appearing in this week's Proceedings of the National Academy of Sciences, Tim Palmer (Oxford University), and Bjorn Stevens (Max Planck Society), critically reflect on the present state of Earth system modelling.

Fairy-wrens change breeding habits to cope with climate change
Warmer temperatures linked to climate change are having a big impact on the breeding habits of one of Australia's most recognisable bird species, according to researchers at The Australian National University (ANU).

Believing in climate change doesn't mean you are preparing for climate change, study finds
Notre Dame researchers found that although coastal homeowners may perceive a worsening of climate change-related hazards, these attitudes are largely unrelated to a homeowner's expectations of actual home damage.

Older forests resist change -- climate change, that is
Older forests in eastern North America are less vulnerable to climate change than younger forests, particularly for carbon storage, timber production, and biodiversity, new research finds.

Read More: Climate Change News and Climate Change Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.