Improved Chiral SFC Screening for Analytical Method Development

In this study we describe the evaluation of a recently developed supercritical fluid chromatography (SFC) instrument for automated chiral SFC method development. The greatly improved gradient dwell volume and liquid flow control of the new instrument in combination with the use of shorter columns containing smaller stationary phase particles affords chiral SFC method development that is faster and more universal than previous systems. Chirality 25:799–804, 2013. © 2013 Wiley Periodicals, Inc.     

MAIGO2 is involved in abscisic acid‐mediated response to abiotic stresses and Golgi‐to‐ER retrograde transport

The central role of multisubunit tethering complexes in intracellular trafficking has been established in yeast and mammalian systems. However, little is known about their roles in the stress responses and the early secretory pathway in Arabidopsis. In this study, Maigo2 (MAG2), which is equivalent to the yeast Tip20p and mammalian Rad50‐interacting protein, is found to be required for the responses to salt stress, osmotic stress and abscisic acid in seed germination and vegetative growth, and MAG2‐like (MAG2L) is partially redundant with MAG2 in response to environmental stresses. MAG2 strongly interacts with the central region of ZW10, and both proteins are important as plant endoplasmic reticulum (ER)‐stress regulators. ER morphology and vacuolar protein trafficking are unaffected in the mag2, mag2l and zw10 mutants, and the secretory marker to the apoplast is correctly transported in mag2 plants, which indicate that MAG2 functions as a complex with ZW10, and is potentially involved in Golgi‐to‐ER retrograde trafficking. Therefore, a new role for ER–Golgi membrane trafficking in abiotic‐stress and ER‐stress responses is discovered.     

Fatty acid synthase causes drug resistance by inhibiting TNF-α and ceramide production

Fatty acid synthase (FASN) is a key enzyme in the synthesis of palmitate, the precursor of major nutritional, energetic, and signaling lipids. FASN expression is upregulated in many human cancers and appears to be important for cancer cell survival. Overexpression of FASN has also been found to associate with poor prognosis and higher risk of recurrence of human cancers. Indeed, elevated FASN expression has been shown to contribute to drug resistance. However, the mechanism of FASN-mediated drug resistance is currently unknown. In this study, we show that FASN overexpression causes resistance to multiple anticancer drugs via inhibiting drug-induced ceramide production, caspase 8 activation, and apoptosis. We also show that FASN overexpression suppresses tumor necrosis factor-α production and nuclear factor-κB activation as well as drug-induced activation of neutral sphingomyelinase. Thus, TNF-α may play an important role in mediating FASN function in drug resistance.     

Betaine attenuates Alzheimer‐like pathological changes and memory deficits induced by homocysteine

Hyperhomocysteinemia (Hhcy) may induce memory deficits with β‐amyloid (Aβ) accumulation and tau hyperphosphorylation. Simultaneous supplement of folate and vitamin B12 partially restored the plasma homocysteine level and attenuated tau hyperphosphorylation, Aβ accumulation and memory impairments induced by Hhcy. However, folate and vitamin B12 treatment have no effects on Hhcy which has the methylenetetrahydrofolate reductase genotype mutation. In this study, we investigated the effects of simultaneous supplement of betaine on Alzheimer‐like pathological changes and memory deficits in hyperhomocysteinemic rats after a 2‐week induction by vena caudalis injection of homocysteine (Hcy). We found that supplementation of betaine could ameliorate the Hcy‐induced memory deficits, enhance long‐term potentiation (LTP) and increase dendritic branches numbers and the density of the dendritic spines, with up‐regulation of NR1, NR2A, synaptotagmin, synaptophysin, and phosphorylated synapsin I protein levels. Supplementation of betaine also attenuated the Hcy‐induced tau hyperphosphorylation at multiple AD‐related sites through activation protein phosphatase‐2A (PP2A) with decreased inhibitory demethylated PP2A_C at Leu309 and phosphorylated PP2A_C at Tyr307. In addition, supplementation of betaine also decreased Aβ production with decreased presenilin‐1 protein levels. Our data suggest that betaine could be a promising candidate for arresting Hcy‐induced AD‐like pathological changes and memory deficits.     

Cardiomyocyte-specific perilipin 5 overexpression leads to myocardial steatosis and modest cardiac dysfunction

Presence of ectopic lipid droplets (LDs) in cardiac muscle is associated to lipotoxicity and tissue dysfunction. However, presence of LDs in heart is also observed in physiological conditions, such as when cellular energy needs and energy production from mitochondria fatty acid β-oxidation are high (fasting). This suggests that development of tissue lipotoxicity and dysfunction is not simply due to the presence of LDs in cardiac muscle but due at least in part to alterations in LD function. To examine the function of cardiac LDs, we obtained transgenic mice with heart-specific perilipin 5 (Plin5) overexpression (MHC-Plin5), a member of the perilipin protein family. Hearts from MHC-Plin5 mice expressed at least 4-fold higher levels of plin5 and exhibited a 3.5-fold increase in triglyceride content versus nontransgenic littermates. Chronic cardiac excess of LDs was found to result in mild heart dysfunction with decreased expression of peroxisome proliferator-activated receptor (PPAR)α target genes, decreased mitochondria function, and left ventricular concentric hypertrophia. Lack of more severe heart function complications may have been prevented by a strong increased expression of oxidative-induced genes via NF-E2-related factor 2 antioxidative pathway. Perilipin 5 regulates the formation and stabilization of cardiac LDs, and it promotes cardiac steatosis without major heart function impairment.     

Molecular tagging of a novel rust resistance gene R 12 in sunflower (Helianthus annuus L.)

Sunflower production in North America has recently suffered economic losses in yield and seed quality from sunflower rust (Puccinia helianthi Schwein.) because of the increasing incidence and lack of resistance to new rust races. RHA 464, a newly released sunflower male fertility restorer line, is resistant to both of the most predominant and most virulent rust races identified in the Northern Great Plains of the USA. The gene conditioning rust resistance in RHA 464 originated from wild Helianthus annuus L., but has not been molecularly marked or determined to be independent from other rust loci. The objectives of this study are to identify molecular markers linked to the rust resistance gene and to investigate the allelism of this gene with the unmapped rust resistance genes present in HA-R6, HA-R8 and RHA 397. Virulence phenotypes of seedlings for the F₂ population and F_2:3 families suggested that a single dominant gene confers rust resistance in RHA 464, and this gene was designated as R ₁₂ . Bulked segregant analysis identified ten markers polymorphic between resistant and susceptible bulks. In subsequent genetic mapping, the ten markers covered 33.4 cM of genetic distance on linkage group 11 of sunflower. A co-dominant marker CRT275-11 is the closest marker distal to R ₁₂ with a genetic distance of 1.0 cM, while ZVG53, a dominant marker linked in the repulsion phase, is proximal to R ₁₂ with a genetic distance of 9.6 cM. The allelism test demonstrated that R ₁₂ is not allelic to the rust resistance genes in HA-R6, HA-R8 and RHA 397, and it is also not linked to any previously mapped rust resistance genes. Discovery of the R ₁₂ novel rust resistance locus in sunflower and associated markers will potentially support the molecular marker-assisted introgression and pyramiding of R ₁₂ into sunflower breeding lines.     

Genetic transformation and genes for resistance to abiotic and biotic stresses in Citrus and its related genera

Citrus is the most important tree fruit crop in the world. However, citrus production is affected by both biotic and abiotic stresses, including drought, extreme temperature, salinity, citrus canker, citrus tristeza virus, and Huanglongbing (or citrus greening), among others. These stresses can severely influence growth and development of both rootstocks and/or scions of citrus trees, thus reducing both fruit production and fruit quality. Modern advances in the tools of plant biotechnology and advances in genomics play important roles in understanding how citrus crops can cope with diseases and adverse environmental conditions. Within the last decades, much progress has been made in identifying and cloning of genes involved in resistance to biotic and abiotic stresses as well in genetic transformation of Citrus and its related genera, such as Poncirus trifoliata and Fortunella spp. In this review, we will provide information on advances and insights on genetic transformation protocols as well as availability of characterized genes involved in resistance to both abiotic and biotic stresses. This will be followed with a discussion on perspectives of future developments in this field.