Temperature effects on forest herbs assessed by warming and transplant experiments along a latitudinal gradient

Slow‐colonizing forest understorey plants are probably not able to rapidly adjust their distribution range following large‐scale climate change. Therefore, the acclimation potential to climate change within their actual occupied habitats will likely be key for their short‐ and long‐term persistence. We combined transplant experiments along a latitudinal gradient with open‐top chambers to assess the effects of temperature on phenology, growth and reproductive performance of multiple populations of slow‐colonizing understorey plants, using the spring flowering geophytic forb Anemone nemorosa and the early summer flowering grass Milium effusum as study species. In both species, emergence time and start of flowering clearly advanced with increasing temperatures. Vegetative growth (plant height, aboveground biomass) and reproductive success (seed mass, seed germination and germinable seed output) of A. nemorosa benefited from higher temperatures. Climate warming may thus increase future competitive ability and colonization rates of this species. Apart from the effects on phenology, growth and reproductive performance of M. effusum generally decreased when transplanted southwards (e.g., plant size and number of individuals decreased towards the south) and was probably more limited by light availability in the south. Specific leaf area of both species increased when transplanted southwards, but decreased with open‐top chamber installation in A. nemorosa. In general, individuals of both species transplanted at the home site performed best, suggesting local adaptation. We conclude that contrasting understorey plants may display divergent plasticity in response to changing temperatures which may alter future understorey community dynamics.     

滇黔数种颇饶趣味的菌物

本文报道了我国西南地区所产担子菌类3新种:即采自贵州省梵净山的梵净山小奥德蘑Oudemansiella fanjingshanensis Zang et Wu(白蘑科Tricholomataceae);威宁县境的贵州华牛肝菌Sinoboletut guizhouensis Zang et Wu(牛肝菌科Boletaceae)和采自云南省哀牢山的巨盖鬼笔Phallus megacephalus Zang(鬼笔科Phallaceae).文中并讨论了有关该新分类群的地理区系成分,田中线划分的见解。     

Superoxide radical production during the autoxidation of 1-methyl-4-phenyl-2,3-dihydropyridinium perchlorate.

1-Methyl-4-phenyl-2,3-dihydropyridinium perchlorate (MPDP+), an intermediate in the metabolism of the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, was found to generate superoxide radicals during its autoxidation process. The generation of superoxide radicals was detected by their ability to reduce ferricytochrome c. Superoxide dismutase inhibited this reduction in a dose-dependent manner. The rate of reduction of ferricytochrome c was dependent not only on the concentration of MPDP+ but also on the pH of the system. Thus, the rate of autoxidation of MPDP+ and the sensitivity of this autoxidation to superoxide dismutase-inhibitable ferricytochrome c reduction were both augmented, as the pH was raised from 7.0 to 10.5. The rate constant (Kc) for the reaction of superoxide radical with ferricytochrome c to form ferricytochrome c was found to be 3.48 x 10(5) M-1 s-1. The rate constant (KMPDP+) for the reaction of MPDP+ with ferricytochrome3+ c was found to be only 4.86 M-1 s-1. These results, in conjunction with complexities in the kinetics, lead to the proposal that autoxidation of MPDP+ proceeds by at least two distinct pathways, one of which involves the production of superoxide radicals and hence is inhibitable by superoxide dismutase. It is possible that the free radicals so generated could induce oxidative injury which may be central to the MPTP/MPDP(+)-induced neuropathy.     

TAXONOMY, MYCOGEOGRAPHY AND ECTO-MYCORRHIZAL ASSOCIATION OF THE BOLETALES FROM CHINA Ⅰ. FAMILY STROBILOMYCETACEAE

TAXoNOMYSPeciesintheorderBoIetalesisusual1yrnycorrhizalandsaprobic,occasionallyhyperpansihc,mostareedjble,afewpoisonous.ThebasidiocarPsarefleshy,readi1ydecay,withtubularhymenoPhore.CommoulyareaccePted2driilies:inthebolyStrobi1omycetaceae,thesporesareomamentedwithsuperficialsculptUring,orperforate-punctate,oulynalysmoothwhenyoung.InthebolyBoletaCeae,thesporesarealwnyssmooth,onlyrarelyroughinmature.FamilyStrobilomycetaceaeKeytothegeneral.Hymenophorewhite,pallidorgrayishwhenyoung,becoming…     

山东泰山种子植物区系的研究

泰山位于山东中部,共有种子植物１００科４０７属７５７种。世界性单型属和少型属共有５１属,占总属数的１２．５％,并有不少起源古老的科、表明了本区系起源的古老性。中国种子植物区系的１５种类型在泰山均有分布,其中北温带分布居首位,占３４．５％,泛热分布次之,占１９．１％,再次是旧世界温带分布和东亚分布,分别占１４．３％和１０．１％。类温带性质属共有２５７属,占７２．２％,而热带质属有则９９属,占２７．８     

AMP-activated protein kinase is required for the lipid-lowering effect of metformin in insulin-resistant human HepG2 cells

The antidiabetic drug metformin stimulates AMP-activated protein kinase (AMPK) activity in the liver and in skeletal muscle. To better understand the role of AMPK in the regulation of hepatic lipids, we studied the effect of metformin on AMPK and its downstream effector, acetyl-CoA carboxylase (ACC), as well as on lipid content in cultured human hepatoma HepG2 cells. Metformin increased Thr-172 phosphorylation of the alpha subunit of AMPK in a dose- and time-dependent manner. In parallel, phosphorylation of ACC at Ser-79 was increased, which was consistent with decreasing ACC activity. Intracellular triacylglycerol and cholesterol contents were also decreased. These effects of metformin were mimicked or completely abrogated by adenoviral-mediated expression of a constitutively active AMPKalpha or a kinase-inactive AMPKalpha, respectively. An insulin-resistant state was induced by exposing cells to 30 mm glucose as indicated by decreased phosphorylation of Akt and its downstream effector, glycogen synthase kinase 3alpha/beta. Under these conditions, the phosphorylation of AMPK and ACC was also decreased, and the level of hepatocellular triacylglycerols increased. The inhibition of AMPK and the accumulation of lipids caused by high glucose concentrations were prevented either by metformin or by expressing the constitutively active AMPKalpha. The kinase-inactive AMPKalpha increased lipid content and blocked the ability of metformin to decrease lipid accumulation caused by high glucose concentrations. Taken together, these results indicate that AMPKalpha negatively regulates ACC activity and hepatic lipid content. Inhibition of AMPK may contribute to lipid accumulation induced by high concentrations of glucose associated with insulin resistance. Metformin lowers hepatic lipid content by activating AMPK, thereby mediating beneficial effects in hyperglycemia and insulin resistance.     

白藜芦醇心血管保护作用研究进展

白藜芦醇(resveratrol)是广泛存在于水果、中药和葡萄酒中的一种植物抗毒素,具有多种生物学作用。本文主要从白藜芦醇减少心肌缺血-再灌注损伤、舒张血管、抗动脉粥样硬化等方面对其心血管保护作用及其机制作一综述。     

High-level expression of recombinant human paraoxonase 1 Q in silkworm larvae (Bombyx mori)

Human serum paraoxonase 1 (hPON1) belongs to a family of enzymes that catalyze the hydrolysis of a broad range of esters and lactones. Although the very first identification of hPON1 might have been as a calcium-dependent paraoxonase/arylesterase, PON1 is in fact a lactonase associated with high-density lipoprotein and strongly stimulated by apoA-I. PON1 hydrolyzes various organophosphates, including insecticides and nerve gases. PON1 also plays a key role in prevention of atherosclerosis. Mediation of cholesterol efflux from macrophage is a key in vivo function of PON1. In present study, the hPON1 Q gene was cloned into baculovirus transfer vector pVL1392 and expressed in silkworm expression system. The rhPON1 Q presented two bands with every near molecular weight of about 40 and 43 kDa according to sodium dodecyl sulphate-polyacrylamide gel electrophoresis and Western blotting analysis. The expression level was up to 1,256 mg/L in haemolymph, about 50 times as high as that from BmN cells (24.8 mg/L). After purified by two chromatography steps (DEAE-Sepharose and HiTrap Chelating HP), the purity of rhPON1 Q was up to 90%, and the enzymatic properties are similar to serum hPON1.     

山东省十地市人轮状病毒分子流行病学研究

用核酸凝胶电泳法对1985—1986年山东省十地市的318份婴幼儿急性腹泻粪便标本中测出的170份HRV阳性标本作了RNA电泳型分析,发现3个地区为HRVI亚群流行,3个地区为HRVⅡ亚群流行,4个地区为两亚群共同流行,共检出差异电泳型34个,其中14个属长RNA电泳型,20个属短RNA电泳型。在一个地区虽有多个差异电泳型毒株流行,但仅有其中的1—2个占流行优势。在两亚群毒株共同流行区,检出的差异电泳型特别多。本文并对HRV RNA电泳型多形性的原因及意义进行了讨论。