Environmental factors that affect the ability of amylose to contribute to retrogradation in gels made from rice flour     

Philpot K  Martin M  Butardo V  Willoughby D  Fitzgerald M 《Journal of agricultural and food chemistry》2006,54(14):5182-5190

Retrogradation in rice is a trait that describes the hardening of cooked rice after storage or cooling, and it has significant implications for many consumers of rice, since many people cook rice in the morning and consume it several hours later or the next day. Tools to select against retrogradation in breeding programs are yet to be described. Here, we aim to determine the effect on retrogradation of storage time and temperature and the role of starch, protein, and lipids using gels made from Koshihikari grown in either Australia or Japan. Immediately after cooking, cooling from 60 to 40 degrees C had a minimal effect on firmness, but cooling to 20 degrees C led to significantly firmer gels. Storing the gels at low temperatures did not have an additional effect on the firmness as compared with storing the gels at 20, 40, or 60 degrees C. The removal of proteins led to significantly softer gels at all storage treatments but did not affect the change in firmness on cooling. The removal of lipids increased the rate of retrogradation and the firmness of gels significantly for all treatments. Koshihikari grown in Japan retrograded much less than Koshihikari grown in Australia. The amount of amylose that could be washed from gels made from Australian flour was much greater than for gels made from Japanese flour. After storage, only low molecular weight amylose chains were released from the gel and only after rewarming them to 60 degrees C. Despite the fact that flours from both origins were 18% amylose, the amount of long amylose chains that were complexed with lipids was much greater for the Japanese rice, and the unavailability of the complexed long amylose chains explained the lack of retrogradation in the Japanese rice. Once the long chains were released from amylose-lipid complexes, the Japanese rice retrograded. Thus, the environmental factor affecting retrogradation in this variety is type or amount of lipids synthesized, and the degree of retrogradation was determined by the availability of long chains of amylose.  相似文献   

Evolution of the earliest horses driven by climate change in the Paleocene-Eocene Thermal Maximum     

Secord R  Bloch JI  Chester SG  Boyer DM  Wood AR  Wing SL  Kraus MJ  McInerney FA  Krigbaum J 《Science (New York, N.Y.)》2012,335(6071):959-962

Body size plays a critical role in mammalian ecology and physiology. Previous research has shown that many mammals became smaller during the Paleocene-Eocene Thermal Maximum (PETM), but the timing and magnitude of that change relative to climate change have been unclear. A high-resolution record of continental climate and equid body size change shows a directional size decrease of ~30% over the first ~130,000 years of the PETM, followed by a ~76% increase in the recovery phase of the PETM. These size changes are negatively correlated with temperature inferred from oxygen isotopes in mammal teeth and were probably driven by shifts in temperature and possibly high atmospheric CO(2) concentrations. These findings could be important for understanding mammalian evolutionary responses to future global warming.  相似文献   

Letters to the Editor ◆ Lettres À La Rédaction: Inappropriate title          下载免费PDF全文

Doug Hare 《The Canadian veterinary journal. La revue veterinaire canadienne》1997,38(6):331

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The end of an era          下载免费PDF全文

Doug Hare 《The Canadian veterinary journal. La revue veterinaire canadienne》2002,43(2):77-80

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Effective communication     

Roberts D 《The Canadian veterinary journal. La revue veterinaire canadienne》2011,52(5):457-460

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Environmental genome shotgun sequencing of the Sargasso Sea   总被引：4，自引：0，他引：4  

Venter JC  Remington K  Heidelberg JF  Halpern AL  Rusch D  Eisen JA  Wu D  Paulsen I  Nelson KE  Nelson W  Fouts DE  Levy S  Knap AH  Lomas MW  Nealson K  White O  Peterson J  Hoffman J  Parsons R  Baden-Tillson H  Pfannkoch C  Rogers YH  Smith HO 《Science (New York, N.Y.)》2004,304(5667):66-74

We have applied "whole-genome shotgun sequencing" to microbial populations collected en masse on tangential flow and impact filters from seawater samples collected from the Sargasso Sea near Bermuda. A total of 1.045 billion base pairs of nonredundant sequence was generated, annotated, and analyzed to elucidate the gene content, diversity, and relative abundance of the organisms within these environmental samples. These data are estimated to derive from at least 1800 genomic species based on sequence relatedness, including 148 previously unknown bacterial phylotypes. We have identified over 1.2 million previously unknown genes represented in these samples, including more than 782 new rhodopsin-like photoreceptors. Variation in species present and stoichiometry suggests substantial oceanic microbial diversity.  相似文献   

Periodic mesoporous organosilicas containing interconnected [Si(CH2)]3 rings     

Landskron K  Hatton BD  Perovic DD  Ozin GA 《Science (New York, N.Y.)》2003,302(5643):266-269

A periodic mesoporous organosilica composed of interconnected three-ring [Si(CH2)]3 units built of three SiO2(CH2)2 tetrahedral subunits is reported. It represents the archetype of a previously unknown class of nanocomposite materials in which two bridging organic groups are bound to each silicon atom. It can be obtained with powder and oriented film morphologies. The nanocomposite is self-assembled from the cyclic three-ring silsesquioxane [(EtO)2Si(CH2)]3 precursor and a surfactant mesophase to give a well-ordered mesoporous framework. Low dielectric constants and good mechanical stability of the films were measured, making this material interesting for microelectronic applications. Methylene group reactivity of the three-ring precursor provides entry to a family of nanocomposites, exemplified by the synthesis and self-assembly of [(EtO)2Si(CHR)][(EtO)2Si(CH2)]2 (where R indicates iodine, bromine, or an ethyl group).  相似文献   

外源DNA导入水稻体细胞胚研究初报     

刘选明  周朴华  洪亚辉  董延瑜  徐庆国  伏军 《湖南农业大学学报(自然科学版)》1994,(6)

以水稻Ｒ２８８的幼穗为外植体，培养在附加激素的ＭＳ固体培养基上诱导出愈伤组织，挑选胚性愈伤组织进行液体振荡培养，建立体细胞悬浮细胞系，诱导出体细胞胚并大量增殖．用水稻紫香糯幼苗为材料提取其ＤＮＡ，以不同浓度ＤＮＡ浸泡体细胞胚，发现体细胞胚的生长发育与试管苗发生了明显变化．试管苗移植大田，获得了种子，植株矮小．初步表明外源ＤＮＡ导入体细胞胚能够诱发变异．  相似文献   

Defining Useful Limits for Spectral Reflectance Measures in Corn     

Wade E. Thomason  Steve B. Phillips  F. Doug Raymond 《Journal of plant nutrition》2013,36(8):1263-1277

Recent work has shown that spectral measurements from a corn (Zea mays L.) canopy can be used to reliably predict differences in growth and nutrient status. Most researchers have found that the accuracy of this assessment increases as the season progresses. In contrast, real differences upon which to base management decisions need to be measured as early in the season as possible due to the time restrictions associated with fertilizer and chemical application equipment and weather. The objectives of this research were to evaluate the relationship between Normalized Difference Vegetative Index (NDVI) measurements and corn biomass and grain yield and to define upper and lower limits for effectively using NDVI measurements to make in-season management decisions in corn. Forage biomass and grain yield from eight field studies conducted in the Coastal Plain of Virginia in 2005 were compared to indirect measures of spectral reflectance and leaf area index (LAI). The NDVI was well correlated with vegetative forage biomass (R² = 0.81) and LAI (R² = 0.90) within the range 0.27 to 0.82. This range in NDVI values corresponds to 166 to 485 cumulative growing degree days (GDD), and a resultant developmental window of V5 to V9 when NDVI measurement are most useful and appropriate for making in-season management decisions for corn production.  相似文献   

Activation of the Nuclear Factor E2-Related Factor 2 Pathway by Novel Natural Products Halomadurones A–D and a Synthetic Analogue     

Thomas P. Wyche  Miranda Standiford  Yanpeng Hou  Doug Braun  Delinda A. Johnson  Jeffrey A. Johnson  Tim S. Bugni 《Marine drugs》2013,11(12):5089-5099

Two novel chlorinated pyrones, halomadurones A and B, and two novel brominated analogues, halomadurones C and D, were isolated from a marine Actinomadura sp. cultivated from the ascidian Ecteinascidia turbinata. Additionally, a non-halogenated analogue, 2-methyl-6-((E)-3-methyl-1,3-hexadiene)-γ-pyrone, was synthesized to understand the role of the halogens for activity. Halomadurones C and D demonstrated potent nuclear factor E2-related factor antioxidant response element (Nrf2-ARE) activation, which is an important therapeutic approach for treatment of neurodegenerative diseases.  相似文献