Production of the infant formula ingredient 1,3-olein-2-palmitin in Arabidopsis thaliana seeds.

In human milk fat, palmitic acid (16:0) is esterified to the middle (sn-2 or β) position on the glycerol backbone and oleic acid (18:1) predominantly to the outer positions, giving the triacylglycerol (TG) a distinctive stereoisomeric structure that is believed to assist nutrient absorption in the infant gut. However, the fat used in most infant formulas is derived from plants, which preferentially esterify 16:0 to the outer positions. We have previously showed that the metabolism of the model oilseed Arabidopsis thaliana can be engineered to incorporate 16:0 into the middle position of TG.

Engineering the stereoisomeric structure of seed oil to mimic human milk fat.

Human milk fat substitute (HMFS) is a class of structured lipid that is widely used as an ingredient in infant formulas. Like human milk fat, HMFS is characterized by enrichment of palmitoyl (C16:0) groups specifically at the middle (sn-2 or β) position on the glycerol backbone, and there is evidence that triacylglycerol (TAG) with this unusual stereoisomeric structure provides nutritional benefits. HMFS is currently made by in vitro enzyme-based catalysis because there is no appropriate biological alternative to human milk fat.

The impact of reducing fatty acid desaturation on the composition and thermal stability of rapeseed oil.

Oilseed rape (Brassica napus) is the third largest source of vegetable oil globally. In addition to food uses, there are industrial applications that exploit the ability of the species to accumulate the very-long-chain fatty acid (VLCFA) erucic acid in its seed oil, controlled by orthologues of FATTY ACID ELONGASE 1 (Bna.FAE1.

Fatty acids in arbuscular mycorrhizal fungi are synthesized by the host plant.

Plants form beneficial associations with arbuscular mycorrhizal fungi, which facilitate nutrient acquisition from the soil. In return, the fungi receive organic carbon from the plants. The transcription factor RAM1 (REQUIRED FOR ARBUSCULAR MYCORRHIZATION 1) is crucial for this symbiosis, and we demonstrate that it is required and sufficient for the induction of a lipid biosynthetic pathway that is expressed in plant cells accommodating fungal arbuscules.

Expression of Castor LPAT2 Enhances Ricinoleic Acid Content at the sn-2 Position of Triacylglycerols in Lesquerella Seed.

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.

Reducing isozyme competition increases target fatty acid accumulation in seed triacylglycerols of transgenic Arabidopsis.

One goal of green chemistry is the production of industrially useful fatty acids (FAs) in crop plants. We focus on hydroxy fatty acids (HFAs) and conjugated polyenoic FAs (α-eleostearic acids [ESAs]) using Arabidopsis (Arabidopsis thaliana) as a model. These FAs are found naturally in seed oils of castor (Ricinus communis) and tung tree (Vernicia fordii), respectively, and used for the production of lubricants, nylon, and paints.

Seed Storage Reserve Analysis.

One of the major goals of plant research is to improve crop yield, by for instance increasing seed oil or protein content. Besides this, extensive research is done to change seed fatty acid (FA) composition in order to make vegetable oils more suitable for specific purposes. To determine the effect of genetic changes on seed FA composition, oil, protein and sugar content it's important to use standardised protocols to compare results between different research groups.

Multigene engineering of triacylglycerol metabolism boosts seed oil content in Arabidopsis.

Increasing the yield of oilseed crops is an important objective for biotechnologists. A number of individual genes involved in triacylglycerol metabolism have previously been reported to enhance the oil content of seeds when their expression is altered. However, it has yet to be established whether specific combinations of these genes can be used to achieve an additive effect and whether this leads to enhanced yield.

bZIP67 regulates the omega-3 fatty acid content of Arabidopsis seed oil by activating fatty acid desaturase3.

Arabidopsis thaliana seed maturation is accompanied by the deposition of storage oil, rich in the essential ω-3 polyunsaturated fatty acid α-linolenic acid (ALA). The synthesis of ALA is highly responsive to the level of fatty acid desaturase3 (FAD3) expression, which is strongly upregulated during embryogenesis. By screening mutants in leafy cotyledon1 (LEC1)-inducible transcription factors using fatty acid profiling, we identified two mutants (lec1-like and bzip67) with a seed lipid phenotype.

The sugar-dependent1 lipase limits triacylglycerol accumulation in vegetative tissues of Arabidopsis.

There has been considerable interest recently in the prospect of engineering crops to produce triacylglycerol (TAG) in their vegetative tissues as a means to achieve a step change in oil yield. Here, we show that disruption of TAG hydrolysis in the Arabidopsis (Arabidopsis thaliana) lipase mutant sugar-dependent1 (sdp1) leads to a substantial accumulation of TAG in roots and stems but comparatively much lower TAG accumulation in leaves. TAG content in sdp1 roots increases with the age of the plant and can reach more than 1% of dry weight at maturity, a 50-fold increase over the wild type.

Castor phospholipid:diacylglycerol acyltransferase facilitates efficient metabolism of hydroxy fatty acids in transgenic Arabidopsis.

Producing unusual fatty acids (FAs) in crop plants has been a long-standing goal of green chemistry. However, expression of the enzymes that catalyze the primary synthesis of these unusual FAs in transgenic plants typically results in low levels of the desired FA. For example, seed-specific expression of castor (Ricinus communis) fatty acid hydroxylase (RcFAH) in Arabidopsis (Arabidopsis thaliana) resulted in only 17% hydroxy fatty acids (HFAs) in the seed oil.

Regulation of the cellulose synthase-like gene family by light in the maize mesocotyl.

The cellulose synthase-like (ZmCSL) gene family of maize was annotated and its expression studied in the maize mesocotyl. A total of 28 full-length CSL genes and another 13 partial sequences were annotated; four are predicted to be pseudogenes. Maize has all of the CSL subfamilies that are present in rice, but the CSLC subfamily is expanded from 6 in rice to 12 in maize, and the CSLH subfamily might be reduced from 3 to 1.

AtPARN is an essential poly(A) ribonuclease in Arabidopsis.

Deadenylation is the first and rate-limiting step in the degradation of many mRNAs in a wide-range of organisms from yeast to higher eukaryotes. It can also play a regulatory role in early development. In this study, we examined the Arabidopsis homolog of poly(A) ribonuclease (PARN), a deadenylase first identified in mammals and absent from yeast.

ARC6 is a J-domain plastid division protein and an evolutionary descendant of the cyanobacterial cell division protein Ftn2.

Replication of chloroplasts is essential for achieving and maintaining optimal plastid numbers in plant cells. The plastid division machinery contains components of both endosymbiotic and host cell origin, but little is known about the regulation and molecular mechanisms that govern the division process. The Arabidopsis mutant arc6 is defective in plastid division, and its leaf mesophyll cells contain only one or two grossly enlarged chloroplasts.

Subcellular localization and oligomerization of the Arabidopsis thaliana somatic embryogenesis receptor kinase 1 protein.

The Arabidopsis thaliana somatic embryogenesis receptor kinase 1 (AtSERK1) gene is expressed in developing ovules and early embryos. AtSERK1 is also transiently expressed during somatic embryogenesis. The predicted AtSERK1 protein contains an extracellular domain with a leucine zipper motif followed by five leucine-rich repeats, a proline-rich region, a single transmembrane region and an intracellular kinase domain.

R-ras interacts with rasGAP, neurofibromin and c-raf but does not regulate cell growth or differentiation.

Within the superfamily of ras-related GTP-binding proteins, only ras itself has been shown to act as an oncogene. Seven other proteins, however, have greater than 50% amino acid identity to ras and one of them, rap1A, has been shown to interact with the ras GTPase activating protein, ras-GAP, and to inhibit ras function when overexpressed. In this paper, we have examined the biological and biochemical activities of another close relative of ras, R-ras.

Characterization of rhoGAP. A GTPase-activating protein for rho-related small GTPases.

GTPase-activating proteins or GAPs play an important role in signal transduction pathways regulated by GTP-binding proteins. In addition to acting as down-regulators of GTPases, there is growing evidence that they also act as effector molecules required for downstream signaling. PLC-beta 1, the target protein regulated by the heterotrimeric GTPase Gq, has been shown to be a GAP, whereas rasGAP, a down-regulator of the small GTPase ras, may be required for the ras-mediated signals.

Protein tyrosine kinases in human brain and gliomas.

Tyrosine kinase activity was determined in neonatal and adult human brain, oligodendrogliomas, and astrocytomas. The astrocytomas were divided into low- (grade I and grade II) and high-grade (grade III and grade IV) tumors. We measured the tyrosine kinase activity in the cytosolic and membrane fraction using poly(glutamic acid:tyrosine, 4:1) as an artificial substrate.

Cellular expression of K-type pyruvate kinase in normal and neoplastic human tissues.

The cellular expression of K-type pyruvate kinase was studied immunohistochemically in several normal and neoplastic tissues of human origin. The authors used the monoclonal antibody, designated as ES1, which was raised against human K-type pyruvate kinase. In contrast to the normal counterparts, a strong immunoreactivity was found in a rhabdomyosarcoma (n = 1), in a carcinoma of the pancreas (n = 1), and in neurofibromas (n = 2).

Phosphofructokinase and pyruvate kinase in mouse embryonal carcinoma P19 cells in relation to growth and differentiation.

Two key enzymes of glycolysis, phosphofructokinase and pyruvate kinase, were studied in embryonal carcinoma cells (P19 EC cells) and three differentiated derivatives in relation to growth rate and differentiation state. The growth rates of P19 EC cells and its differentiated derivatives are positively correlated with both the specific activity of phosphofructokinase and the expression of the L-subunit of this enzyme. The specific activity of pyruvate kinase and its isozyme composition is not correlated with growth rate but seems to be correlated with the differentiation state of these cells.

Production and characterization of monoclonal antibodies against human type K pyruvate kinase.

K-type pyruvate kinase was purified from human kidney by immunoadsorbant chromatography. Monoclonal antibodies secreting hybridomas were made using conventional techniques. Two clones were established which produced antibodies against K-type not cross-reacting with the other pyruvate kinase isoenzymes, named the M, L and R-types.

Inactivation of human plasma kallikrein and factor XIa by protein C inhibitor.

The inhibition of kallikrein and factor XIa by protein C inhibitor (PCI) was studied. The method of Suzuki et al. [Suzuki, K.

Periplasmic accumulation of truncated forms of outer-membrane PhoE protein of Escherichia coli K-12.

In order to localize the information within PhoE protein of Escherichia coli K-12 required for export of the protein to the outer membrane, we have generated deletions throughout the phoE gene. Immunocytochemical labelling on ultrathin cryosections revealed that the polypeptides encoded by the mutant alleles are transported to, and accumulate in, the periplasm. These results show that, except for the signal sequence, there is no specific sequence within the PhoE protein that is essential for transport through the cytoplasmic membrane.