{"id":39503,"date":"2011-07-05T07:58:51","date_gmt":"2011-07-05T11:58:51","guid":{"rendered":"https:\/\/today.uconn.edu\/?p=39503"},"modified":"2015-09-24T14:33:24","modified_gmt":"2015-09-24T18:33:24","slug":"glowing-squid-thrive-in-symbiotic-relationship","status":"publish","type":"post","link":"https:\/\/today.uconn.edu\/2011\/07\/glowing-squid-thrive-in-symbiotic-relationship\/","title":{"rendered":"Glowing Squid Thrive in Symbiotic Relationship"},"content":{"rendered":"

In the middle of summer, our thoughts often turn to things that have to do with the ocean. Sand. Sea. Sailing. Even Squid!\u00a0 In keeping with this theme, the following is a reprint of a story that originally appeared in UConn Today in March of 2010. <\/em><\/p>\n

\"\"<\/a>
Spencer Nyholm, assistant professor of molecular and cell biology, with a Hawaiian Bobtail Squid. Photo by Jessica Tommaselli<\/figcaption><\/figure>\n

Bacteria generally have a bad reputation \u2013 they\u2019re good only for causing disease, and are best avoided. But Spencer Nyholm of the molecular and cell biology<\/strong><\/a> department in the College of Liberal Arts and Sciences sees things differently.<\/p>\n

\u201cMore than 90 percent of the cells in our bodies are bacteria,\u201d Nyholm points out. \u201cSome live on our skin, and many live in our intestines, providing vitamins and aiding us in digestion.\u201d<\/p>\n

These mutually advantageous relationships, called beneficial symbioses, occur when a symbiont, such as a bacterium, lives within and exchanges resources with a host animal or plant. Nyholm\u2019s research on one particular beneficial symbiosis is not only exciting in a visual sense \u2013 he studies a glowing squid \u2013 but is helping scientists understand how immune systems distinguish friend from foe.<\/p>\n

The relationship that Nyholm and his students study involves the tiny Hawaiian bobtail squid and its symbiotic bacterium, Vibrio fisheri<\/em>. The two-inch-long squid live in the central Pacific, near coral reefs in shallow sand flats, where they bury themselves in the sand during the day and come out at night to feed and reproduce. The bacteria float freely in<\/p>\n

\"\"<\/a>
<Bobtail squid bred by Professor Spencer Nyholm in his saltwater laboratory. The nocturnal squid bury themselves under the sand during the day. Photo by Spencer Nyholm<\/figcaption><\/figure>\n

the ocean water, but when they find themselves in large groups, they produce light.<\/p>\n

During their first few days of life, the nocturnal squid take advantage of this bioluminescence by collecting a population of the bacteria into a specialized light organ within their bodies. The aggregated bacteria light up the animal\u2019s underside, which helps to defend the squid from predators, says Nyholm.<\/p>\n

\u201cThese squid don\u2019t have a lot of defenses: they\u2019re small and they\u2019re soft,\u201d he says. \u201cSo they use light to protect themselves.\u201d<\/p>\n

By producing light on their undersides, says Nyholm, their silhouettes blend in with the moonlight above, making it difficult for predators below, such as fish, seals, and sharks, to see them. In return, the squid provides nutrients and a safe haven to the bacteria.<\/p>\n

Each morning, however, as the squid are settling down to sleep, they spit out about 95 percent of the Vibrio<\/em> bacteria into the surrounding water. Why would the squid effectively rid themselves of a perfectly good defense mechanism?<\/p>\n

There are two main reasons, says Nyholm. First, as the bacteria age, they might become toxic to the squid. Secondly, releasing the bacteria bolsters the number of free-living Vibrio<\/em>, so baby squid have a stock of bacteria to draw from.<\/p>\n

Besides, Nyholm points out, a 95 percent population reduction is nothing for bacteria. After expulsion, the remaining 5<\/p>\n

\"\"<\/a>
Bobtail squid provide a home within their body cavity for luminescent squid, which helps camouflage them against moonlight. Photo by Mattias Ormestad<\/figcaption><\/figure>\n

percent of the squid\u2019s bacteria replicate throughout the day and by the time the sun sets, the squid is re-equipped with a full 100 percent.<\/p>\n

The squid\u2019s unusual life cycle isn\u2019t the only reason this symbiosis is interesting to scientists. In a recent paper published<\/p>\n

in the Proceedings of the National Academy of Sciences<\/strong><\/a>, Nyholm and his colleagues show that this daily rhythm is tightly woven into the organisms\u2019 genetics, and suggest that the same might be true for bacteria in the guts of humans and other mammals.<\/p>\n

Nyholm also recently received a grant of more than $600,000 from the National Science Foundation<\/strong><\/a> to study the squid\u2019s immune system. Unlike many symbioses \u2013 for example, in the human gut, which contains hundreds of different beneficial species of bacteria \u2013 these squid maintain a relationship with only one species. When baby squid collect bacteria from seawater, their immune cells need to know which bacteria to accept and which to destroy.<\/p>\n

\u201cIn this case, we can study how the specific bacteria and host communicate with each other,\u201d Nyholm says. \u201cThis can tell us a lot about immune system function and how it distinguishes beneficial from harmful bacteria. It helps us to tease apart the conversation between blood cells and symbionts.\u201d<\/p>\n

\"\"<\/a>
A Hawaiian Bobtail Squid. Photo by Jessica Tommaselli<\/figcaption><\/figure>\n

Although Vibrio<\/em> fisheri<\/em> are beneficial to squid, a closely related bacterium, Vibrio cholerae<\/em>, causes cholera in humans. Nyholm hopes that his work will help to discover what characteristics of this group of bacteria are potentially harmful.<\/p>\n

\u201cUnderstanding how the squid immune system reacts to Vibrio<\/em> bacteria can help us understand how other animals interact with both beneficial and disease-causing microbes,\u201d he says. \u201cThe genes of communication appear to be similar for good and bad associations, but the mechanisms of implementation are likely different.\u201d<\/p>\n

To read more about Nyholm\u2019s work, go to the Molecular and Cell Biology online newsletter, MCB Notes<\/strong><\/a> (PDF).<\/p>\n","protected":false},"excerpt":{"rendered":"

Glowing squid help scientists learn about the immune system. They look neat, too.<\/p>\n","protected":false},"author":21,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_crdt_document":"","wds_primary_category":0,"wds_primary_series":0,"wds_primary_attribution":0,"footnotes":""},"categories":[2076],"tags":[],"magazine-issues":[],"coauthors":[56],"class_list":["post-39503","post","type-post","status-publish","format-standard","hentry","category-research"],"pp_statuses_selecting_workflow":false,"pp_workflow_action":"current","pp_status_selection":"publish","acf":[],"publishpress_future_action":{"enabled":false,"date":"2026-04-12 16:40:49","action":"change-status","newStatus":"draft","terms":[],"taxonomy":"category","extraData":[]},"publishpress_future_workflow_manual_trigger":{"enabledWorkflows":[]},"_links":{"self":[{"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/posts\/39503","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/users\/21"}],"replies":[{"embeddable":true,"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/comments?post=39503"}],"version-history":[{"count":6,"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/posts\/39503\/revisions"}],"predecessor-version":[{"id":104753,"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/posts\/39503\/revisions\/104753"}],"wp:attachment":[{"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/media?parent=39503"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/categories?post=39503"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/tags?post=39503"},{"taxonomy":"magazine-issue","embeddable":true,"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/magazine-issues?post=39503"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/today.uconn.edu\/wp-rest\/wp\/v2\/coauthors?post=39503"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}