Patrick J Horn

• Ph.D Biochemistry
• Professor (Assistant) at University of North Texas

Lipids and oils derived from plant and algal photosynthesis constitute much of human daily caloric intake and provide the basis for high-energy bioproducts, chemical feedstocks for countless applications, and even fossil fuels over geological time scales. Sustainable production of high-energy compounds from plants is essential to preserving fossil...

Plants produce structurally and functionally diverse metabolites that are key to many physiological processes such as growth and development, reproduction, defense, and stress responses. Underlying this chemical diversity are numerous enzyme-catalyzed (oxidoreductase) reactions that transfer electrons between molecular species altering their respec...

Imaging has long supported our ability to understand the inner life of plants, their development, and response to a dynamic environment. While optical microscopy remains the core tool for imaging, a suite of novel technologies is now beginning to make a significant contribution to visualize plant metabolism. The purpose of this review was to provid...

Mass spectrometry imaging (MSI) has emerged as an invaluable analytical technique for investigating the spatial distribution of molecules within biological systems. In the realm of plant science, MSI is increasingly employed to explore metabolic processes across a wide array of plant tissues, including those in leaves, fruits, stems, roots, and see...

Plant neutral lipids, also known as “vegetable oils”, are synthesized within the endoplasmic reticulum (ER) membrane and packaged into subcellular compartments called lipid droplets (LDs) for stable storage in the cytoplasm. The biogenesis, modulation, and degradation of cytoplasmic LDs in plant cells are orchestrated by a variety of proteins local...

In the wake of increasing demand for renewable energy sources, plant-based sources including alternative oilseeds have come to the forefront of interest. Hydroxy fatty acids (HFAs), produced in a few oilseed species, are important chemical feedstocks for industrial applications. An integrated approach was taken to assemble the first draft genome of...

Cysteines (Cys) are chemically reactive amino acids containing sulfur that play diverse roles in plant biology. Recent proteomics investigations in Arabidopsis thaliana have revealed the presence of thiol post-translational modifications (PTMs) on several Cys residues. These PTMs are presumed to impact protein structure and function, yet mechanisti...

Using a population of recombinant inbred lines (RILs) cowpea (Vigna unguiculata. L. Walp), we tested for co‐linkages between lipid contents and chilling responses of photosynthesis. Under low temperature conditions (19°C/13°C, day/night), we observed co‐linkages between quantitative trait loci (QTL) intervals for photosynthetic light reactions and...

Using a population of recombinant inbred lines (RILs) cowpea ( Vigna unguiculata. L. Walp), we tested for co-linkages between lipid contents and chilling responses of photosynthesis. Under low temperature conditions (19°C/13°C, day/night), we observed co-linkages between quantitative trait loci (QTL) intervals for photosynthetic light reactions and...

Cytosolic lipid droplets (LDs) are organelles which emulsify a variety of hydrophobic molecules in the aqueous cytoplasm of essentially all plant cells. Most familiar are the LDs from oilseeds or oleaginous fruits that primarily store triacylglycerols and serve a storage function. However, similar hydrophobic particles are found in cells of plant t...

African Americans endure a nearly two-fold greater risk of suffering a stroke and are 2–3 times more likely to die from stroke compared to those of European ancestry. African Americans also have a greater risk of recurrent stroke and vascular events, which are deadlier and more disabling than incident stroke. Stroke is a multifactorial disease with...

Thylakoid membrane lipids, comprised of glycolipids and the phospholipid phosphatidylglycerol (PG), are essential for normal plant growth and development. Unlike other lipid classes, chloroplast PG in nearly all plants contains a substantial fraction of the unusual trans fatty acid 16:1Δ3trans or 16:1t. We determined that in Arabidopsis thaliana, 1...

The marine microalgae Nannochloropsis oceanica (CCMP1779) is a prolific producer of oil and is considered a viable and sustainable resource for biofuel feedstocks. Nitrogen (N) availability has a strong impact on the physiological status and metabolism of microalgal cells, but the exact nature of this response is poorly understood. To fill this gap...

In plant lipid metabolism, the synthesis of many intermediates or end products often appears overdetermined with multiple synthesis pathways acting in parallel. Lipid metabolism is also dynamic with interorganelle transport, turnover, and remodeling of lipids. To explore this complexity in vivo, we developed an in vivo lipid “tag and track” method....

Figure S1 Map of binary plant expression vectors. Figure S2 Seed oil content as a percentage of dry weight. Figure S3 Germination and growth of transgenic camelina in soil (a and c) and " MS plus 1% sucrose medium (b). Seeds from control fad2/fae1 and transgenic lines collected at the same time were compared for germination testing. (c) T4 genera...

Modified fatty acids (mFA) have diverse uses, e.g., cyclopropane fatty acids (CPA) are feedstocks for producing coatings, lubricants, plastics, and cosmetics. The expression of mFA-producing enzymes in crop and model plants generally results in lower levels of mFA accumulation than in their natural-occurring source plants. Thus, to further our unde...

Main conclusion: Genetically diverse cottonseeds show altered compositions and spatial distributions of phosphatidylcholines and triacylglycerols. Lipidomics profiling led to the discovery of a novel FAD2 - 1 allele, fad2 - 1D - 1 , resulting in a high oleic phenotype. The domestication and breeding of cotton for elite, high-fiber cultivars have l...

Rationale: Refined cottonseed oil has widespread applications in the food and chemical industries. Although the major lipids comprising cottonseed oil (triacylglycerols) are well known, there are many diverse lipid species in cotton seeds that occur at much lower levels and have important nutritional or anti-nutritional properties. Methods: The...

Historically, the primary objective of cotton (Gossypium hirsutum L.) breeding programs was to improve the quantity and quality of cotton fiber. Because of the added value of cottonseed and its many uses, including a feed and human food source, there is interest in developing cotton breeding programs that focus improvement efforts simultaneously on...

Two Brassicaceae species, Physaria fendleri and Camelina sativa, are genetically very closely related to each other and to Arabidopsis thaliana. Physaria fendleri seeds store over 50% hydroxy fatty acids (HFAs) while Camelina and Arabidopsis do not accumulate HFAs. To better understand how plants evolved new biochemical pathways with the capacity t...

In this study, sub-2 µm particle CO2 based supercritical chromatography (UltraPerformance Convergence Chromatography, UPC2) was investigated for the separation of free fatty acids, neutral and polar lipids in cottonseed extract. Typically, plant metabolomic profiling distinguishes heterogeneous distribution of neutral lipids; such as triacylglycero...

Recent studies have suggested that cottonseed (Gossypium spp.) has the potential to contribute to the effort against world hunger, particularly by providing a high-quality protein source. This report analyzed the diversity in protein content and other seed quality factors in the U.S. National Cotton Germplasm Collection. Nine genomes (one tetraploi...

In this study, sub-2 µm particle CO2 based supercritical chromatography was investigated for the separation of free fatty acids, neutral and polar lipids in cottonseed extract. Typically, plant metabolomic profiling distinguishes heterogeneous distribution of neutral lipids; such as triacylglycerols and diacylgylcerols at different conditions. The...

Mass spectrometry (MS) is currently the most utilized analytical instrument for evaluating the metabolite composition of a biological sample at both the qualitative and quantitative level. The exponential growth of raw data generated through increasingly versatile mass spectrometers requires sophisticated algorithms to process and visualize the raw...

Despite the plethora of information on seed characteristics and seedling vigor in cotton, the near-continuous release of new cultivars coupled with limited information on seedling vigor for field conditions necessitates re-evaluation of seed characteristics important for vigorous seedling growth and plant establishment. Consequently, seedling vigor...

The emergence of 'omics technologies (i.e. genomics, proteomics, metabolomics, etc.) have revealed new avenues for exploring plant metabolism through data-rich experimentation and integration of complementary methodologies. Over the past decade, the lipidomics field has benefited from advances in instrumentation, especially mass spectrometry (MS)-b...

While lipid droplets have traditionally been considered as inert sites for the storage of triacylglycerols and sterol esters, they are now recognized as dynamic and functionally diverse organelles involved in energy homeostasis, lipid signaling, and stress responses. Unlike most other organelles, lipid droplets are delineated by a half-unit membran...

Identifying and reporting genetic variability is an important tool to increase the utilization of germplasm collections. In an effort to further realize the potential of cottonseed, we have characterized seed composition traits of Gossypium spp. accessions available in the U.S. National Cotton Germplasm Collection (NCGC). This characterization will...

A standardized experiment was conducted during 2009 and 2010 at 20 location-years across U.S. cotton (Gossypium hirsutum L.)-producing states to compare the N use requirement of contemporary cotton cultivars based on their planting seed size. Treatments consisted of three cotton varieties with planting seed of different numbers of seed per kg and N...

High biomass crops have recently attracted significant attention as an alternative platform for the renewable production of high energy storage lipids such as triacylglycerol (TAG). While TAG typically accumulates in seeds as storage compounds fuelling subsequent germination, levels in vegetative tissues are generally low. Here, we report the accum...

TLC screening of leaf tissue of Nicotiana tabacum T0 events at flowering stage as described in materials and methods. Lanes 42–44 are wild-type controls, which have relatively low TAG compared with the T0 transgenic event in lane 3 (described in this study). Figure S2 Southern blot of transgenic Nicotiana tabacum leaf DNA with NPTII probe demonstra...

Targeted increases in monounsaturated (oleic acid) fatty acid content of refined cottonseed oil could support improved human nutrition and cardiovascular health. Genetic modifications of cottonseed fatty acid composition have been accomplished using several different molecular strategies. Modification of oleic acid content in cottonseed embryos usi...

Lipid droplets in plants (also known as oil bodies, lipid bodies or oleosomes) are well characterized in seeds, and oleosins, the major proteins associated with their surface, were shown to be important for stabilizing lipid droplets during seed desiccation and rehydration. However, lipid droplets occur in essentially all plant cell types, many of...

Engineering compositional changes in oilseeds is typically accomplished by introducing new enzymatic step(s) and/or by blocking or enhancing an existing enzymatic step(s) in a seed-specific manner. However, in practice, amounts of lipid species that accumulate in seeds are often different from what one would predict from enzyme expression levels, a...

COMPARATIVE GENE IDENTIFICATION-58 (CGI-58) is a key regulator of lipid metabolism and signaling in mammals, but its underlying mechanisms are unclear. Disruption of CGI-58 in either mammals or plants results in a significant increase in triacylglycerol (TAG), suggesting that CGI-58 activity is evolutionarily conserved. However, plants lack protein...

Developments in instrumentation aimed at microscopic sampling have led to an emphasis on applications analyzing small volumes and molecular concentrations within biological, chemical, and industrial samples. Simultaneous improvements in the sensitivity and versatility of nanospray mass spectrometers have made it possible to directly couple these sa...

CGI‐58 (Comparative Gene Identification‐58) encodes an α/β hydrolase‐type protein that is involved in multiple aspects of lipid metabolism in mammals, including the breakdown of triacylglycerols (TAGs) and formation of the hydrophobic barrier of the skin. Mutations in CGI‐58 result not only in aberrant skin formation, but also in accumulation of li...

Advances in mass spectrometry (MS) have made comprehensive lipidomics analysis of complex tissues relatively commonplace. These compositional analyses, although able to resolve hundreds of molecular species of lipids in single extracts, lose the original cellular context from which these lipids are derived. Recently, high-resolution MS of individua...

Advances in mass spectrometry (MS) have made comprehensive lipidomics analysis of complex tissues relatively commonplace. These compositional analyses, although able to resolve hundreds of molecular species of lipids in single extracts, lose the original cellular context from which these lipids are derived. Recently, high-resolution MS of individua...

Mass spectrometry (MS) advances in recent years have revolutionized the biochemical analysis of lipids in plants, and made possible new theories about the structural diversity and functional complexity of lipids in plant cells. Approaches have been developed to profile the lipidome of plants with increasing chemical and spatial resolution. Here we...

Modification of cottonseed quality traits is likely to be achieved through a combination of genetic modification, manipulation of nutrient allocation, and selective breeding. Oil and protein stores account for the majority of mass of cottonseed embryos. A more comprehensive understanding of the relationship between lint quality, lint yield, and emb...

A wealth of information related to lipid metabolism and signaling has been revealed in recent years using mass spectrometric-based lipidomics methods. Although quantitatively sensitive, these compositional profiling methods rely on conventional tissue extractions of total lipids which results in a loss of original cellular context of lipid metaboli...

Lipins are phosphatidate phosphatases that generate diacylglycerol (DAG). In this study, we report that yeast lipin, Pah1p, controls the formation of cytosolic lipid droplets. Disruption of PAH1 resulted in a 63% decrease in droplet number, although total neutral lipid levels did not change. This was accompanied by an accumulation of neutral lipids...

An expanding appreciation for the varied functions of neutral lipids in cellular organisms relies on a more detailed understanding of the mechanisms of lipid production and packaging into cytosolic lipid droplets (LDs). Conventional lipid profiling procedures involve the analysis of tissue extracts and consequently lack cellular or subcellular reso...

CGI-58 is the defective gene in the human neutral lipid storage disease called Chanarin-Dorfman syndrome. This disorder causes intracellular lipid droplets to accumulate in nonadipose tissues, such as skin and blood cells. Here, disruption of the homologous CGI-58 gene in Arabidopsis thaliana resulted in the accumulation of neutral lipid droplets i...