黄土高原冬小麦田光谱特征变化及其与二氧化碳日收支的相关分析

根据光谱辐射仪对黄土高原冬小麦整个生育期光谱反射率的连续观测数据及CO₂通量观测数据,对冬小麦田光谱特征变化及其与CO₂日收支的相关性进行了分析.结果表明：冬小麦田不同波长光谱反射率和归一化植被指数（NDVI）呈现明显的日变化和季节变化.同一天内,反射率随太阳高度角的变化而变化,变化最大的波段（550 nm左右、700～1 050 nm）表现为峰.不同生育期同一时刻,可见光波段（350～670 nm）反射率变化不大,近红外波段（700～1 050 nm）出现较大差异,在出苗期、分蘖期和越冬期后红边位置向长波方向“红移”;越冬期前出现向短波方向“蓝移” 的现象;但成熟期“蓝移”现象不明显,表现为突变;其他生育时期没有观测到波谱位移.NDVI的日变化呈U型,13：00左右最低,16：00后出现较大波动,与抛物线有较好的拟合效果,小麦生长旺盛时期,对其地面遥感观测应选择在NDVI变化不大的13：00左右进行;整个冬小麦生长季11:00反射率及NDVI以播种后第140天为中心对称,NDVI的季节变化表现为M型,可用四次多项式拟合;在整个小麦生育期中NDVI与CO₂的日收支呈极显著负相关,但正午左右的相关性稍差.     

Theoretical insights into the effect of pH values on oxidation processes in the emission of firefly luciferin in aqueous solution

To elucidate the emission process of firefly d ‐luciferin oxidation across the pH range of 7–9, we identified the emission process by comparison of the potential and free‐energy profiles for the formation of the firefly substrate and emitter, including intermediate molecules such as d ‐luciferyl adenylate, 4‐membered dioxetanone, and their deprotonated chemical species. From these relative free energies, it is observed that the oxidation pathway changes from d ‐luciferin → deprotonated d ‐luciferyl adenylate → deprotonated 4‐membered dioxetanone → oxyluciferin to deprotonated d ‐luciferin → deprotonated d ‐luciferyl adenylate → deprotonated 4‐membered dioxetanone → oxyluciferin with increasing pH value. This indicates that deprotonation on 6′OH occurs during the formation of dioxetanone at pH 7–8, whereas luciferin in the reactant has a 6′OH‐deprotonated form at pH 9.     

Slow-down of age-dependent telomere shortening is executed in human skin keratinocytes by hormesis-like-effects of trace hydrogen peroxide or by anti-oxidative effects of pro-vitamin C in common concurrently with reduction of intracellular oxidative stress

The cellular life-span of cultivated human skin epidermis keratinocytes NHEK-F was shown to be extended up to 150% of population doubling levels (PDLs) by repetitive addition with two autooxidation-resistant derivatives of ascorbic acid (Asc), Asc-2-O-phosphate (Asc2P), and Asc-2-O-alpha-glucoside (Asc2G), respectively, but to be not extended with Asc itself. In contrast, hydrogen peroxide (H(2)O(2)) as dilute as 20 microM which was non-cytotoxic to the keratinocytes, or at 60 microM being marginally cytotoxic achieved the cellular longevity, unexpectedly, up to 160 and 120% of PDLs, respectively, being regarded as a hormesis-like stimulatory effect. The lifespan-extended cells that were administered with Asc2P, Asc2G, or 20 microM H(2)O(2) were prevented from senescence-induced symptoms such as PDL-dependent enlargement of a cell size of 14.7 microm finally up to 17.4 microm upon Hayflick's limit-called loss of proliferation ability as estimated with a channelizer, and retained young cell morphological aspects such as thick and compact shape and intense attachment to the culture substratum even upon advanced PDLs, whereas other non-extended cells looked like thin or fibrous shape and large size upon lower PDLs. The PDL-dependent shortening of telomeric DNA of 11.5 kb finally down to 9.12-8.10 kb upon Hayflick's limit was observed in common for each additive-given cells, but was decelerated in the following order: 20 microM H(2)O(2) > Asc2P = Asc2G > 60 microM H(2)O(2) > Asc = no additive, being in accord with the order of cell longevity. Intracellular reactive oxygen species (ROS) was diminished by Asc2P, Asc2G or 20 microM H(2)O(2), but not significantly by Asc or 60 microM H(2)O(2) as estimated by fluorometry using the redox indicator dye CDCFH. There was no appreciable difference among NHEK keratinocytes that were administered with or without diverse additives in terms of telomerase activity per cell, which was 1.40 x 10(4)-4.48 x 10(4) times lower for the keratinocytes than for HeLa cells which were examined as the typical tumor cells. Thus longevity of the keratinocytes was suggested to be achieved by slowdown of age-dependent shortening of telomeric DNA rather than by telomerase; telomeres may suffer from less DNA lesions due to the continuous and thorough repression of intracellular ROS, which was realized either by pro-vitamin C such as Asc2P or Asc2G that exerted an antioxidant ability more persistent than Asc itself or by 20 microM H(2)O(2) which diminished intracellular ROS assumedly through a hormesis-like effect.     

Genetic,morphological, and virulence characterization of the entomopathogenic fungus Verticillium lecanii

In order to clarify relationships among genetic diversity, virulence, and other characteristics of conidia, 46 isolates of Verticillium lecanii from various hosts and geographical locations were examined. The internal transcribed spacer (ITS) and intergenic spacer (IGS) regions of ribosomal DNA (rDNA), mitochondrial small subunit rDNA (mt-SrDNA) and beta-tubulin were analyzed by PCR-RFLP. PCR-single stranded conformational polymorphism (SSCP) was performed on regions of the mitochondrial large subunit rDNA, mt-SrDNA, beta-tubulin and histone 4. There were no relationships among the results of RFLP, SSCP, isolation source, and location. However, amplified product size of IGS did have relationships with conidia size and sporulation. Six isolates with 4.0-kb IGS products had large conidia dimensions, and yielded low numbers of conidia compared with other isolates. Three out of the six isolates were high virulence (over 90%) against green peach aphids. Furthermore, double-stranded RNA (dsRNA) was detected in 22 out of 35 V. lecanii isolates and related with the amplicon sizes of IGS, though not with virulence or isolation location. Isolates containing dsRNA were divided into six distinct types based on banding pattern. These data demonstrate the level of genetic diversity of V. lecanii, and suggest relations among the genetic properties and conidial morphology.     

Molecular cloning and characterization of prokineticin receptors

Recent studies have identified two novel biofunctional proteins, termed prokineticin 1/EG-VEGF and prokineticin 2, which were mammalian homologues of mamba MIT1 and frog Bv8. Prokineticins have been demonstrated to exert their physiological functions through G-protein coupled receptors (GPCRs). In this study, we report the molecular identification of two endogenous prokineticin receptors, designated PK-R1 and PK-R2, through a search of the human genomic DNA database. PK-R1, locating in chromosome 2, and PK-R2, locating in chromosome 20p13, shared 87% homology, which was an extremely high value among known GPCRs. In functional assays, mammalian cells expressing PK-Rs responded to prokineticins in a concentration-dependent manner. Tissue distribution analysis revealed that expression of PK-R1 was observed in the testis, medulla oblongata, skeletal muscle and skin, while that of PK-R2 showed preferential expression in the central nervous system. The tissue distribution of PK-Rs reported in this paper suggests that the prokineticins play multifunctional roles in vivo.     

TAB2, a novel adaptor protein, mediates activation of TAK1 MAPKKK by linking TAK1 to TRAF6 in the IL-1 signal transduction pathway

The TAK1 MAPKKK mediates activation of JNK and NF-KB in the IL-1-activated signaling pathway. Here we report the identification of TAB2, a novel intermediate in the IL-1 pathway that functionally links TAK1 to TRAF6. Expression of TAB2 induces JNK and NF-kappaB activation, whereas a dominant-negative mutant TAB2 impairs their activation by IL-1. IL-1 stimulates translocation of TAB2 from the membrane to the cytosol where it mediates the IL-1-dependent association of TAK1 with TRAF6. These results define TAB2 as an adaptor linking TAK1 and TRAF6 and as a mediator of TAK1 activation in the IL-1 signaling pathway.     

Identification of MrgX2 as a human G-protein-coupled receptor for proadrenomedullin N-terminal peptides

Pleiotrophin (PTN) is a heparin-binding growth/differentiation inducing cytokine that shares 50% amino acid sequence identity and striking domain homology with Midkine (MK), the only other member of the Ptn/Mk developmental gene family. The Ptn gene is expressed in sites of early vascular development in embryos and in healing wounds and its constitutive expression in many human tumors is associated with an angiogenic phenotype, suggesting that PTN has an important role in angiogenesis during development and in wound repair and advanced malignancies. To directly test whether PTN is angiogenic in vivo, we injected a plasmid to express PTN into ischemic myocardium in rats. Pleiotrophin stimulated statistically significant increases in both normal appearing new capillaries and arterioles each of which had readily detectable levels of the arteriole marker, smooth muscle cell alpha-actin. Furthermore, the newly formed blood vessels were shown to interconnect with the existent coronary vascular system. The results of these studies demonstrate directly that PTN is an effective angiogenic agent in vivo able to initiate new vessel formation that is both normal in appearance and function. The data suggest that PTN signals the more "complete" new blood vessel formation through its ability to stimulate different functions in different cell types not limited to the endothelial cell.     

Leaf development in the absence of a shoot apical meristem in Zeylanidium subulatum (Podostemaceae)

* BACKGROUND AND AIMS: The Podostemaceae are a family of unusual aquatic angiosperms that live in rapids and waterfalls. To adapt to such extreme habitats, the family shows unusual morphologies. This study investigated the developmental anatomy of the shoot of Zeylanidium subulatum borne on the prostrate root attached to submerged rock surfaces. * METHODS: Shoots of Z. subulatum were observed under the microscope using resin-sections. * KEY RESULTS: The shoot has no shoot apical meristem (SAM) and, without it, forms leaves distichously dorsiventrally facing the immediately older leaf. A new leaf forms on the adaxial side of a pre-existing leaf and also on the abaxial side of a leaf on flowering shoots. In both cases, the young leaf is endogenous below the older leaf and maintains histological continuity with it. Shortly after internal initiation, the leaf primordia become separate from each other due to cleavage between adjacent leaves of opposite ranks. The cleavage is caused by intercellular separation as well as by degeneration of vacuolated cells. Loss of the SAM is probably linked with the speculated shift of the site of leaf formation to the root. * CONCLUSIONS: The 'shoot' of Z. subulatum is characterized by the absence of a SAM, endogenous leaf formation in the absence of a SAM, cleavage between leaf primordia, and adventitious leaf formations. These innovations occur in some Podostemaceae that have become increasingly adapted to extreme aquatic habitats.