Publications by authors named "David McCaskill"

Article Synopsis
  • DHA is primarily sourced from marine fish, but bioengineered crops could provide a more sustainable and cost-effective alternative.
  • Researchers identified and characterized lysophosphatidic acid acyltransferases (LPAATs) from algae and soybeans to increase DHA in seed oils, particularly in the sn-2 position of triacylglycerol (TAG).
  • The study found significant increases in sn-2 DHA levels in transgenic Arabidopsis, indicating that genetic modifications can enhance DHA accumulation, paving the way for improved omega-3 sources in crops like canola and soybean.
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Soybeans (Glycine max (L.) Merr.) genetically modified to express aryloxyalkanoate dioxygenase-12 (AAD-12), an enzyme that confers resistance to the herbicide 2,4-D, can sometimes exhibit a darker seed coat coloration than equivalent unmodified soybeans.

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Background: RNA interference (RNAi) triggered by maize plants expressing RNA hairpins against specific western corn rootworm (WCR) transcripts have proven to be effective at controlling this pest. To provide robust crop protection, mRNA transcripts targeted by double-stranded RNA must be sensitive to knockdown and encode essential proteins.

Results: Using WCR adult feeding assays, we identified Sec23 as a highly lethal RNAi target.

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Cry6Aa1 is a () toxin active against nematodes and corn rootworm insects. Its 3D molecular structure, which has been recently elucidated, is unique among those known for other toxins. Typical three-domain toxins permeabilize receptor-free planar lipid bilayers (PLBs) by forming pores at doses in the 1-50 μg/ml range.

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Background: The Cry6 family of proteins from Bacillus thuringiensis represents a group of powerful toxins with great potential for use in the control of coleopteran insects and of nematode parasites of importance to agriculture. These proteins are unrelated to other insecticidal toxins at the level of their primary sequences and the structure and function of these proteins has been poorly studied to date. This has inhibited our understanding of these toxins and their mode of action, along with our ability to manipulate the proteins to alter their activity to our advantage.

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Article Synopsis
  • The western corn rootworm (WCR) is a significant pest affecting maize in the U.S. Corn Belt, and transgenic maize has been developed with Bt insecticidal proteins to combat this pest.
  • A study investigated the role of a specific cadherin-like gene (DvvCad) in WCR midgut tissue and its potential involvement in the toxicity of Proteins Cry3Aa and Cry34/35Ab1.
  • Findings indicated that knocking down DvvCad expression did not significantly affect larval mortality or growth when WCR were exposed to these proteins, suggesting that cadherin is not a key factor in their toxicity.
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Bacillus thuringiensis strains are well known for the production of insecticidal proteins upon sporulation and these proteins are deposited in parasporal crystalline inclusions. The majority of these insect-specific toxins exhibit three domains in the mature toxin sequence. However, other Cry toxins are structurally and evolutionarily unrelated to this three-domain family and little is known of their three dimensional structures, limiting our understanding of their mechanisms of action and our ability to engineer the proteins to enhance their function.

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In higher plants, three subfamilies of sucrose nonfermenting-1 (Snf1)-related protein kinases have evolved. While the Snf1-related protein kinase 1 (SnRK1) subfamily has been shown to share pivotal roles with the orthologous yeast Snf1 and mammalian AMP-activated protein kinase in modulating energy and metabolic homeostasis, the functional significance of the two plant-specific subfamilies SnRK2 and SnRK3 in these critical processes is poorly understood. We show here that SnRK2.

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Article Synopsis
  • Agricultural biotechnology faces challenges from inefficient methods like random mutagenesis and transgenesis, making plant trait engineering difficult.
  • The study introduces designed zinc-finger nucleases (ZFNs) as a solution, enabling precise genome modifications in crops like Zea mays (corn).
  • Using ZFNs, researchers successfully added a herbicide-tolerance gene to maize, demonstrating that these genetic changes can be reliably passed to future generations, paving the way for improved plant genetic manipulation in agriculture.
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The 15N content of pheophytin, the magnesium-free derivative of chlorophyll, can be measured with great accuracy and precision using positive-ion atmospheric pressure ionization electrospray mass spectroscopy following a simple solvent extraction of small amounts of plant tissue. The molecular weight of pheophytin prepared from Chlamydomonas reinhardtii grown in different ratios of 14N/15N showed linear regression with the isotopic input, with a precision of 0.5-1%.

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