Genetic Technique | ScienceGate

Abstract. Ariyanti Y, Farajallah A. 2019. Species confirmation of juvenile cloudy grouper, Epinephelus erythrurus (Valenciennes, 1828), based on a morphologic analysis and partial CO1 gene sequencing. Biodiversitas 20: 914-921. The genus Epinephelus is the most species among the genera within the subfamily Epinephelinae. Species identification techniques for groupers, especially in the Epinephelus, are commonly based on color patterns and a suite of morphological characters, including body shape and the size and number of fins, scales and gill rakers. In some species, juveniles are morphologically distinct from adults of the same species, making morphological identification highly problematic. This present work will provide some morphological description or variations of juveniles that have been identified as Epinephelus erythrurus based on CO1 sequences. Further, the present study demonstrates that a molecular genetic technique, based on partial sequencing of the mitochondrial CO1 gene, may be used for the rapid species confirmation of every developmental stage and phase of an organism (juvenile E. erythrurus). Two DNA sequences of E. erythrurus from the Pangandaran District (7o43’8.31”S 108o30’11.59”E) have been submitted to GenBank under accession numbers KP998441 and KP998442.

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An engineered bacterium auxotrophic for an unnatural amino acid: a novel biological containment system

10.7287/peerj.preprints.1001 ◽

2015 ◽

Author(s):

Yusuke Kato

Keyword(s):

Amino Acid ◽

Natural Environment ◽

Culture Medium ◽

Stop Codon ◽

Unnatural Amino Acid ◽

Biological Containment ◽

Containment System ◽

Genetic Technique ◽

Colicin E3 ◽

Host Killing

Biological containment is a genetic technique to program dangerous organisms to grow only in the laboratory and to die in the natural environment. Auxotropy for a substance not found in the natural environment is an ideal biological containment. Here, we constructed an Escherichia coli strain that cannot survive in the absence of the unnatural amino acid 3-iodo-L-tyrosine. This synthetic auxotrophy was achieved by conditional production of the antidote protein against the highly toxic enzyme colicin E3. An amber stop codon was inserted in the antidote gene. The translation of the antidote mRNA was controlled by a translational switch using amber-specific 3-iodo-L-tyrosine incorporation. The antidote is synthesized only when 3-iodo-L-tyrosine is present in the culture medium. The viability of this strain rapidly decreased with less than a 1 h half-life after removal of 3-iodo-L-tyrosine, suggesting that the decay of the antidote causes the host killing by activated colicin E3 in the absence of this unnatural amino acid. This containment system can be constructed by only plasmid introduction without genome editing, suggesting that this system may be applicable to other microbes carrying toxin-antidote systems similar to that of colicin E3.

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