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NMSU biology professors research squid, bacteria for NASA grant

Two biology professors at New Mexico State University were awarded a nearly $800,000 three-year NASA grant to study how biological changes in bacteria affect complex organisms.


A green squid
The Australian species of squid Euprymna tasmanica, also known as the dumpling squid. Regents Professor of Biology Michele Nishiguchi and assistant professor of biology Maria Castillo will travel to Australia in January to collect these squids in order to conduct research, for which they've been given an $800,000 grant by NASA. (Courtesy photo)
Woman looking in a bucket
Regents Professor of Biology Michele Nishiguchi sorts through squids collected from Kurnell Beach in Australia on a previous trip. (Courtesy photo)
Woman’s portrait
Assistant professor of biology Maria Castillo. (Courtesy photo)

NMSU Regents Professor Michele Nishiguchi and assistant professor Maria Castillo are both in the Department of Biology in the College of Arts and Sciences. Nishiguchi specializes in microbial ecology research while Castillo’s research has focused primarily on comparative invertebrate immunology in squids.

“NASA has an exobiology program to look at the evolution of life on Earth, as well as on other planets and how life may have existed and could exist again on other planets,” Nishiguchi said.

Nishiguchi and Castillo intend to conduct their research by experimenting on how altered Vibrio bacteria affect host squids.

“Vibrio bacteria are important microbes to squids because the bacteria colonizes the squid and produces bioluminescence, which the squid utilizes as a form of counterillumination and uses it for hunting and preventing detection by predators,” Castillo said.

Nishiguchi and Castillo will manipulate the Vibrio bacteria in various experiments by changing the salinity, temperature, pH, or ultra-violent radiation the bacteria are exposed to in order to mimic conditions of early Earth or what is observed in today’s changing climate.

“After the bacteria have been altered, we’ll introduce the bacteria to newly hatched squids to see how the bacteria interact with the squids’ immune systems,” Nishiguchi said.

“If the altered bacteria are beneficial for the squids, they’ll retain it,” Castillo said. “If the bacteria aren’t good for them or are harmful, the squids will reject the bacteria.”

In the latter case, the two will then examine why the squids rejected the bacteria and what immune function was used to identify beneficial versus less fit bacteria in the squid.

The adult squids collected in the field are used as a breeding colony and won’t be exposed to the bacteria. Instead, the offspring they produce, and the subsequent generations, will be the recipients of the altered bacteria.

“It’s important the squids we work with be ‘blank slates,’ unaffected by the bacteria of their natural environments,” Nishiguchi said.

The species of bobtailed squid Castillo and Nishiguchi are examining lay multiple “clutches” of eggs during their lifetime, each of which take three to four weeks to hatch.

“Bobtail squid juveniles are born without their Vibrio bacteria,” Castillo said. “They get them from their environment. So that’s when we introduce the altered Vibrio bacteria.”

Questions Nishiguchi and Castillo will be working to answer include: How does altered Vibrio bacteria affect the squids’ bioluminescence capabilities? Which processes replicated in the lab to emulate environmental changes are harmful to the Vibrio bacteria’s ability to enable bioluminescence? Which allow the same amount of bioluminescence? And which allow even better bioluminescence?

Nishiguchi and Castillo will be traveling to Australia in January to collect samples. The pair will collaborate with two faculty at the University of New South Wales in Sydney, where they will store the squids they catch before returning to Las Cruces.

Nishiguchi said they selected an Australian species of squid (Euprymna tasmanica) in their research because the species is robust and can be raised in the laboratory under artificial conditions more easily than other species. The squids they bring back will be stored in the squid lab located in Foster Hall.

“With this research, we’ll be able to determine how bacteria and animals evolved together when the first multicellular organisms appeared on Earth, and whether specific changes were necessary due to the evolution of this beneficial relationship,” Nishiguchi said. “And we’ll be able to get an idea of what we can do to help keep beneficial associations healthy, like our gut microbiota under changing environmental conditions. The world’s climate is rapidly changing, and it’s important to study associations such as those between animals and bacteria in order to maintain this diversity and the existence of all multicellular life that depends on microbes.”