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The Secret Behind Silkworm's Hardy Stomachs

Date:
May 30, 2008
Source:
American Society for Biochemistry and Molecular Biology
Summary:
Researchers have found that silkworms produce a special digestive enzyme, previously not found in any animals, that is not affected by the toxic chemicals found in mulberry leaves.
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Silkworm eating mulberry leaf.
Credit: Toru Shimada

Silkworms have a unique ability to eat toxic mulberry leaves without feeling ill, and researchers have come one step closer to understanding why: silkworms contain a special digestive enzyme that is not affected by mulberry's toxic chemicals.

Mulberry leaves contain an extremely high amount of alkaloids that inhibit enzymes that break down sucrose (sugar), and thus are potentially quite toxic. However, one type of sucrase called beta-fructofuranosidase is not affected by these alkaloids.

Until now, this enzyme has not been found in any animals, but Toru Shimada and colleagues believed this might explain the silkworm's unique diet.

The researchers scanned the silkworm genome and discovered two fructofuranosidase genes, although only one was actually expressed in the worm. This gene (BmSuc1) was, as expected, concentrated in the worm's gut, although surprisingly was also prevalent in the silk gland. When they isolated the enzyme from silkworms, the researchers found it could effectively digest sucrose.

Shimada and colleagues note that further work is needed to determine if this special enzyme is the sole reason for silkworm's resistance to mulberry toxins. It's possible that fructofuranosidases may turn up in other insects that cannot eat mulberry leaves, indicating additional factors are at work.


Story Source:

The above story is based on materials provided by American Society for Biochemistry and Molecular Biology. Note: Materials may be edited for content and length.


Journal Reference:

  1. Daimon et al. B-fructofuranosidase genes of the silkworm, Bombyx mori: insights into enzymatic adaptation of B. mori to toxic alkaloids in mulberry latex. Journal of Biological Chemistry, 2008; 283 (22): 15271 DOI: 10.1074/jbc.M709350200

Cite This Page:

American Society for Biochemistry and Molecular Biology. "The Secret Behind Silkworm's Hardy Stomachs." ScienceDaily. ScienceDaily, 30 May 2008. <www.sciencedaily.com/releases/2008/05/080527170509.htm>.
American Society for Biochemistry and Molecular Biology. (2008, May 30). The Secret Behind Silkworm's Hardy Stomachs. ScienceDaily. Retrieved May 25, 2015 from www.sciencedaily.com/releases/2008/05/080527170509.htm
American Society for Biochemistry and Molecular Biology. "The Secret Behind Silkworm's Hardy Stomachs." ScienceDaily. www.sciencedaily.com/releases/2008/05/080527170509.htm (accessed May 25, 2015).

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