Publications by authors named "Grace Q Chen"

Background: Castor (Ricinus communis L.) seeds contain unusual fatty acid, hydroxy fatty acid (HFA) used as a chemical feedstock for numerous industrial products. Castor cultivation is limited by the potent toxin ricin in its seeds and other poor agronomic traits, so it is advantageous to develop a suitable HFA-producing crop.

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Seeds of castor () are enriched in oil with high levels of the industrially valuable fatty acid ricinoleic acid (18:1OH), but production of this plant is limited because of the cooccurrence of the ricin toxin in its seeds. Lesquerella () is being developed as an alternative industrial oilseed because its seeds accumulate lesquerolic acid (20:1OH), an elongated form of 18:1OH in seed oil which lacks toxins. Synthesis of 20:1OH is through elongation of 18:1OH by a lesquerella elongase, PfKCS18.

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Article Synopsis
  • Two Phase 3 studies showed bictegravir/emtricitabine/tenofovir alafenamide (B/F/TAF) is as effective as other HIV treatments, with no resistance emerging over 144 weeks.
  • Analysis of resistance after 3 years revealed very low rates of pre-existing drug resistance among participants, which did not impact treatment outcomes.
  • Overall, treatment with B/F/TAF and other regimens led to high and sustained rates of HIV-1 viral suppression, even in individuals with some baseline resistance.
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Hydroxy fatty acids (HFAs) have numerous industrial applications but are absent in most vegetable oils. accumulating 85% HFA in its seed oil makes it a valuable resource for engineering oilseed crops for HFA production. To discover lipid genes involved in HFA synthesis in , transcripts from developing seeds at various stages, as well as leaf and flower buds, were sequenced.

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Objective: The growing prevalence of tobacco use in low "to middle" income countries (LMICs) and the hurdles of conducting tobacco cessation in that context necessitates a focus on the scope of randomized controlled trials (RCTs) in LMICs to guide tobacco cessation in this environment. We conducted a scoping review to identify LMIC tobacco cessation RCTs.

Methods: Consistent with PRISMA-ScR guidelines and without language restrictions, we systematically searched peer-reviewed databases (MEDLINE, Embase, PsycINFO, articles published since inception, latest searches in March 2020) and gray literature (clinical trials registries, searches between September and December 2019).

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Background: Increasing the oil yield is a major objective for oilseed crop improvement. Oil biosynthesis and accumulation are influenced by multiple genes involved in embryo and seed development. The () is a master regulator of embryo development that also enhances the expression of genes involved in fatty acid biosynthesis.

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Background: Perilla (Perilla frutescens (L.) var frutescens) produces high levels of α-linolenic acid (ALA), a ω-3 fatty acid important to health and development. To uncover key genes involved in fatty acid (FA) and triacylglycerol (TAG) synthesis in perilla, we conducted deep sequencing of cDNAs from developing seeds and leaves for understanding the mechanism underlying ALA and seed TAG biosynthesis.

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Lesquerella is a potential industrial oilseed crop that makes hydroxy fatty acid (HFA). Unlike castor its seeds are not poisonous but accumulate lesquerolic acid mostly at the sn-1 and sn-3 positions of triacylglycerol (TAG), whereas castor contains ricinoleic acid (18:1OH) at all three positions. To investigate whether lesquerella can be engineered to accumulate HFAs in the sn-2 position, multiple transgenic lines were made that express castor lysophosphatidic acid acyltransferase 2 (RcLPAT2) in the seed.

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Background: Castor oil is the only commercial source of hydroxy fatty acid that has industrial value. The production of castor oil is hampered by the presence of the toxin ricin in its seed. Lesquerella seed also accumulates hydroxy fatty acid and is free of ricin, and thus it is being developed as a new crop for hydroxy fatty acid production.

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Hydroxy fatty acids produced in plant seed oil are important industrial material. This review focuses on the use of metabolic engineering approaches for the production of hydroxy fatty acids in transgenic plants. Vegetable oil is not only edible but can also be used for industrial purposes.

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Castor oil has many industrial uses. Molecular species of acylglycerols containing monohydroxy, dihydroxy and trihydroxy fatty acids in castor oil have been reported. We report here the identification of acylglycerols containing a triOH18:2 fatty acid in castor oil.

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We studied the temporal and spatial expression of the 2S albumin in castor (Ricinus communis L.) during seed development, germination, post-germination, and plant development. Quantitative polymerase chain reaction analysis showed that the 2S albumin transcript accumulated to a maximum level at the middle of seed development, showing a bell-shaped temporal pattern.

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As part of our effort to identify enzymes that are critical for producing large amounts of ricinoleate in castor oil, we have isolated three cDNAs encoding acyl-CoA synthetase (ACS) in the castor plant. Analysis of the cDNA sequences reveals that two of them, designated RcACS 2 and RcACS 4, contain complete coding regions corresponding to 694 and 690 amino acids, respectively. The third cDNA, RcACS 1, encodes a truncated gene sequence.

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Castor seed triacylglycerols (TAGs) contain 90% ricinoleate (12-hydroxy-oleate) which has numerous industrial applications. Due to the presence of the toxin ricin and potent allergenic 2S albumins in the seed, it is desirable to produce ricinoleate from temperate oilseeds. To identify regulatory genes or genes for enzymes that may up-regulate multiple activities or entire pathways leading to the ricinoleate and TAG synthesis, we have analyzed expression profiles of 12 castor genes involved in fatty acid and TAG synthesis using quantitative reverse transcription-polymerase chain reaction technology.

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Due to the potential for intentional contamination of food with crude preparations containing ricin, a real-time PCR method was developed for the detection of castor plant material in ground beef. One primer pair was identified and confirmed to be castor-specific and efficient for amplification of ricin in DNA extracts from castor or beef matrices. Of three different DNA extraction protocols compared, the hexadecyltrimethylammonium bromide (CTAB) method yielded the highest quality of DNA for QPCR assay.

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The central importance of storage lipid breakdown in providing carbon and energy during seed germination has been demonstrated by isolating the genes encoding the enzymes involved in FA beta-oxidation. In contrast, little is known about the ability of germinating seeds to synthesize TAG. We report that castor cotyledons are capable of TAG synthesis.

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Castor oil is the only commercial source of ricinoleic acid and has numerous industrial applications. Among the factors limiting domestic production of castor oil is the presence of the toxin ricin and its less toxic homologue Ricinus communis agglutinin (RCA) in seeds. Although the sequences of ricin and RCA genes are known, their transcriptional expression patterns have not been distinguished due to their high degree of sequence similarity.

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We have previously reported the cloning of castor diacylglycerol acyltransferase (RcDGAT) based on its homology to other plant type 1 diacylglycerol acyltransferases (DGATs). To elucidate the physiological role of the RcDGAT, we have investigated the regulation of RcDGAT expression in developing seeds of castor. The RcDGAT transcript appeared at 12 d after pollination (DAP), reached the highest level at 26 DAP, and declined rapidly after that.

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The oil from castor seed (Ricinus communis) contains 90% ricinoleate, a hydroxy FA that is used in producing numerous industrial products. Castor diacylglycerol acyltransferase (RcDGAT) is a critical enzyme, as it catalyzes the terminal step in castor oil biosynthesis in which the products contain two or three ricinoleoyl moieties. We have isolated a cDNA encoding RcDGAT from developing castor seeds.

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