Presentation Title

Determining if the K(3) Herbicide Cafenstrole affects Alkenone Biosynthesis in Emiliania huxleyi

Faculty Mentor

Dr. Betsy Read

Start Date

23-11-2019 1:00 PM

End Date

23-11-2019 1:15 PM

Location

Markstein 208

Session

oral 3

Type of Presentation

Oral Talk

Subject Area

biological_agricultural_sciences

Abstract

Emiliania huxleyi (E. hux) is one of the most abundant phytoplankton on this planet. In addition to producing intricate calcium carbonate cell coverings, they are one in five species on the planet to synthesize abnormally long chain fatty acids known as alkenones. Unlike other fatty acids, carbon chain lengths range from 36-40 with one to five trans double bonds. Most phytoplankton store energy in the form of triglycerides but E. hux stores energy as alkenones. For many years’ biogeochemists have used the alkenone desaturation index to estimate sea surface temperatures and construct paleoenvironments. The pathways involved in the biosynthesis and degradation of alkenones however, remain unknown. To determine whether elongases are involved in the synthesis of alkenones we used the K(3) herbicide Cafenstrole which is known to inhibit the synthesis of very-long-chain fatty acids. E. hux cells were plated on a lethal dose of Cafenstrole. Two spontaneous mutants were selected and characterized after growing in batch culture. The growth rates were determined, and neutral lipids were extracted and profiled using gas chromatography-mass spectrometry (GC-MS). The growth rates of the mutants and the wild type were similar whereby the doubling time of the wild type strain CCMP 1516 was 31.5 hrs, Caf Sp1 was 32.5 hrs, and Caf Sp2 was somewhat greater at 39 hrs. In terms of total neutral lipids, the two cafenstrole mutants produced 50% less alkenones and nearly 50% more alkanes compared to the wild-type CCMP 1516. RNA was extracted for transcriptional profiling, and genomic DNA was isolated to identify genomic lesions in the mutants. RNA analysis indicates three elongases are down regulated in the mutant strains. The expression profiles of these and several other genes related to lipid metabolism that are significantly differentially expressed will be described, and progress identifying genomic lesions will also be detailed.

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Nov 23rd, 1:00 PM Nov 23rd, 1:15 PM

Determining if the K(3) Herbicide Cafenstrole affects Alkenone Biosynthesis in Emiliania huxleyi

Markstein 208

Emiliania huxleyi (E. hux) is one of the most abundant phytoplankton on this planet. In addition to producing intricate calcium carbonate cell coverings, they are one in five species on the planet to synthesize abnormally long chain fatty acids known as alkenones. Unlike other fatty acids, carbon chain lengths range from 36-40 with one to five trans double bonds. Most phytoplankton store energy in the form of triglycerides but E. hux stores energy as alkenones. For many years’ biogeochemists have used the alkenone desaturation index to estimate sea surface temperatures and construct paleoenvironments. The pathways involved in the biosynthesis and degradation of alkenones however, remain unknown. To determine whether elongases are involved in the synthesis of alkenones we used the K(3) herbicide Cafenstrole which is known to inhibit the synthesis of very-long-chain fatty acids. E. hux cells were plated on a lethal dose of Cafenstrole. Two spontaneous mutants were selected and characterized after growing in batch culture. The growth rates were determined, and neutral lipids were extracted and profiled using gas chromatography-mass spectrometry (GC-MS). The growth rates of the mutants and the wild type were similar whereby the doubling time of the wild type strain CCMP 1516 was 31.5 hrs, Caf Sp1 was 32.5 hrs, and Caf Sp2 was somewhat greater at 39 hrs. In terms of total neutral lipids, the two cafenstrole mutants produced 50% less alkenones and nearly 50% more alkanes compared to the wild-type CCMP 1516. RNA was extracted for transcriptional profiling, and genomic DNA was isolated to identify genomic lesions in the mutants. RNA analysis indicates three elongases are down regulated in the mutant strains. The expression profiles of these and several other genes related to lipid metabolism that are significantly differentially expressed will be described, and progress identifying genomic lesions will also be detailed.