The absorptive cells of the small intestine, enterocytes, are not generally thought of as a cell type that stores triacylglycerols (TGs) in cytoplasmic lipid droplets (LDs). We revisit TG metabolism in enterocytes by ex vivo and in vivo coherent anti-Stokes Raman scattering (CARS) imaging of small intestine of mice during dietary fat absorption (DFA). We directly visualized the presence of LDs in enterocytes. We determined lipid amount and quantified LD number and size as a function of intestinal location and time post-lipid challenge via gavage feeding. The LDs were confirmed to be primarily TG by biochemical analysis. Combined CARS and fluorescence imaging indicated that the large LDs were located in the cytoplasm, associated with the tail-interacting protein of 47 kDa. Furthermore, in vivo CARS imaging showed real-time variation in the amount of TG stored in LDs through the process of DFA. Our results highlight a dynamic, cytoplasmic TG pool in enterocytes that may play previously unexpected roles in processes, such as regulating postprandial blood TG concentrations. With obesity and cardiovascular disease being worldwide health issues, the impetus of understanding the parameters that govern energy intake and blood lipid concentration has emerged. Blood lipid concentration and a major portion of energy intake are regulated through the highly efficient process of dietary fat absorption (DFA) by the small intestine. Greater than 95% of dietary fat consumed is absorbed whether a low-or high-fat diet is consumed (1), as evidenced by the small amount of fat that is excreted in feces. In the small intestine lumen, dietary fat in the form of triacylglycerol (TG) is hydrolyzed to generate FFAs and monoacylglycerols (MGs) by pancreatic lipase. These products are then emulsified with the help of phospholipids and bile acids present in bile to form micelles. FFAs and MGs are then taken up by the absorptive cells of the small intestine, enterocytes, where they are resynthesized into TGs and incorporated into the core of chylomicrons (CMs), which are secreted via the lymphatic system into the circulation (2, 3).Most current models of the synthesis of CMs show the resynthesized TG in this process entering the lumen of the endoplasmic reticulum (ER) where the assembly of CMs begins and do not highlight the potential for the resynthesized TG to enter a cytoplasmic TG storage pool unless there is a defect in CM synthesis or secretion (1,(3)(4)(5)(6)(7)(8). In fact, wild-type mice fed a high-fat diet, or challenged with an oil bolus by oral gavage, are commonly reported as having no lipid droplet (LD) accumulation in enterocytes (9-11). Nevertheless, both indirect and direct evidence exists supporting the presence of a cytoplasmic storage pool in enterocytes. In humans, sequential meal tests demonstrated that CMs secreted after a second meal carried TG ingested in the first meal (12, 13). In rats, TG is synthesized within 30 s after an intraduodenal fat infusion (14); however, the secretion of TG into the lymph does n...

Multimodal nonlinear optical microscopy is a valuable tool to study complex biological samples. We present an easy-to-operate approach to perform coherent anti-Stokes Raman scattering (CARS), two-photon fluorescence (TPF), second harmonic generation (SHG), and third-harmonic generation (THG) imaging using a single laser source composed of an 80 MHz femtosecond (fs) laser, an optical parametric oscillator (OPO), and a PPLN crystal for frequency doubling. The platform allows vibrationally resonant CARS imaging of CH-rich myelin sheath in fresh spinal tissues and lipid bodies in live cells. Multimodal nonlinear optical imaging and microspectroscopy analysis of fresh liver tissues are demonstrated.

The adoption of pest-resistant transgenic plants to reduce yield loss and pesticide utilization has been successful in the past three decades. Recently, transgenic plant expressing double-stranded RNA (dsRNA) targeting pest genes emerges as a promising strategy for improving pest resistance in crops. The steroid hormone, 20-hydroxyecdysone (20E), predominately controls insect molting via its nuclear receptor complex, EcR-USP. Here we report that pest resistance is improved in transgenic tobacco plants expressing dsRNA of EcR from the cotton bollworm, Helicoverpa armigera, a serious lepidopteran pest for a variety of crops. When H. armigera larvae were fed with the whole transgenic tobacco plants expressing EcR dsRNA, resistance to H. armigera was significantly improved in transgenic plants. Meanwhile, when H. armigera larvae were fed with leaves of transgenic tobacco plants expressing EcR dsRNA, its EcR mRNA level was dramatically decreased causing molting defects and larval lethality. In addition, the transgenic tobacco plants expressing H. armigera EcR dsRNA were also resistant to another lepidopteran pest, the beet armyworm, Spodoptera exigua, due to the high similarity in the nucleotide sequences of their EcR genes. This study provides additional evidence that transgenic plant expressing dsRNA targeting insect-associated genes is able to improve pest resistance.

This article is available online at http://www.jlr.org lipids and bile acids present in bile to form micelles. Free fatty acids and monoacylglycerol are then taken up by the absorptive cells of the small intestine, enterocytes, where they are resynthesized into TGs and incorporated into the core of chylomicrons, which are secreted via the lymphatic system into circulation ( 2 ). TG is then delivered to cells throughout the body, where it serves diverse functions, including energy storage and generation depending on energy status. The postprandial triglyceridemic response (or levels of TG in blood after a meal) is thus dependent on both the appearance of TG in and the clearance of TG from circulation. Because of its high energy density, high effi ciency of absorption, ability to be stored when energy is in excess, and ability to be oxidized to generate energy when needed, dietary fat and its absorption by the small intestine are important determinants of energy balance.TGs synthesized within enterocytes are secreted into circulation in a time-and amount-dependent manner. As the amount of dietary fat increases, postprandial triglyceridemia also increases ( 3, 4 ). In addition, under HF dietary challenges, TG is also found packaged in enterocytes in cytoplasmic lipid droplets (CLDs) ( 5 ). We recently demonstrated that this storage pool of TG in enterocytes expands and depletes relative to the fed-fasted state and is present whether mice are acutely or chronically challenged by high levels of dietary fat ( 5 ). These results suggest that TG stored in CLDs are eventually hydrolyzed, reesterifi ed, and secreted on chylomicrons. The absorption of dietary fat, the most energy-dense nutrient, by the small intestine is a highly effi cient process. Greater than 95% of dietary fat consumed is absorbed whether a low-or high-fat (HF) diet is consumed ( 1 ), as evidenced by the small amount of fat that is excreted in feces. In the small intestine lumen, dietary fat in the form of triacylglycerol (TG) is hydrolyzed to generate free fatty acids and monoacylglycerol by pancreatic lipase. These products are then emulsifi ed with the help of phospho-

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Sericulture has been greatly advanced by applying hybrid breeding techniques to the domesticated silkworm, Bombyx mori, but has reached a plateau during the last decades. For the first time, we report improved silk yield in a GAL4/UAS transgenic silkworm. Overexpression of the Ras1 CA oncogene specifically in the posterior silk gland improved fibroin production and silk yield by 60%, while increasing food consumption by only 20%. Ras activation by Ras1 CA overexpression in the posterior silk gland enhanced phosphorylation levels of Ras downstream effector proteins, up-regulated fibroin mRNA levels, increased total DNA content, and stimulated endoreplication. Moreover, Ras1 activation increased cell and nuclei sizes, enriched subcellular organelles related to protein synthesis, and stimulated ribosome biogenesis for mRNA translation. We conclude that Ras1 activation increases cell size and protein synthesis in the posterior silk gland, leading to silk yield improvement.

Inositol phosphates (IPs) and their turnover products have been implicated to play important roles in stress signaling in eukaryotic cells. In higher plants genes encoding inositol polyphosphate kinases have been identified previously, but their physiological functions have not been fully resolved. Here we expressed Arabidopsis inositol polyphosphate 6-/3-kinase (AtIpk2b) in two heterologous systems, i.e. the yeast Saccharomyces cerevisiae and in tobacco (Nicotiana tabacum), and tested the effect on abiotic stress tolerance. Expression of AtIpk2b rescued the salt-, osmotic-and temperature-sensitive growth defects of a yeast mutant strain (arg82D) that lacks inositol polyphosphate multikinase activity encoded by the ARG82/IPK2 gene. Transgenic tobacco plants constitutively expressing AtIpk2b under the control of the Cauliflower Mosaic Virus 35S promoter were generated and found to exhibit improved tolerance to diverse abiotic stresses when compared to wild type plants. Expression patterns of various stress responsive genes were enhanced, and the activities of anti-oxidative enzymes were elevated in transgenic plants, suggesting a possible involvement of AtIpk2b in plant stress responses.

Short CommunicationDynamic Changes of Sediment Discharge and the Influencing Factors in the Yellow River, China, for the Recent 90 YearsThe dynamic changes in the sediment discharge over 90 years from 1919 to 2008 in the Yellow River in China were assessed on the basis of annual rainfall series and annual sediment series in Shan County hydrological station. The key factors affecting sediment discharge, such as rainfall, and human activities were studied. Anomaly accumulation method and double mass curve were employed to test the stage changes of sediment discharge, and to determine the main factors of sediment decline. Results showed that the annual average sediment discharge under natural conditions was about 16 Â 10 8 t, 1924-1931 and 1979-2008) and a high sediment stage , respectively. Since 1979, there was a significant decreasing trend in the sediment discharge, and the main influencing factor was fierce human activities. Annual average sediment discharge in the post-development period was 69.7% lower than that in the pre-development period , with average reduction of 81 and 19% caused by human activities and rainfall, respectively. These results provide important evidence for making protecting policy for water resources quality and environmental safety of the Yellow River.