Molecular,functional, and cellular alterations of oocytes and cumulus cells induced by heat stress and shock in animals

Environmental Science and Pollution Research - Global warming is considered as the main environmental stress affecting ecosystems as well as physiological and biochemical characteristics, and...     

Do novel genotypes drive the success of an invasive bark beetle-fungus complex? Implications for potential reinvasion

Novel genotypes often arise during biological invasions, but their role in invasion success has rarely been elucidated. Here we examined the population genetics and behavior of the fungus, Leptographium procerum, vectored by a highly invasive bark beetle, Dendroctonus valens, to determine whether genetic changes in the fungus contributed to the invasive success of the beetle-fungal complex in China. The fungus was introduced by the beetle from the United States to China, where we identified several novel genotypes using microsatellite markers. These novel genotypes were more pathogenic to Chinese host seedlings than were other genotypes and they also induced the release of higher amounts of 3-carene, the primary host attractant for the beetle vector, from inoculated seedlings. This evidence suggests a possible mechanism, based on the evolution of a novel genotype during the two or three decades since its introduction, for the success of the beetle-fungal complex in its introduced region.     

Aggregation pheromone of a newly described spruce bark beetle, Ips shangrila Cognato and Sun, from China

Volatiles from male hindgut extracts of a newly described spruce bark beetle, Ips shangrila Cognato and Sun, from different attack phases were analyzed by GC–MS/FID with both polar and enantioselective columns. The GC–MS/FID analyses showed that unmated males (Phase 1) or males mated with <3 females (Phases 2–4) produced 2-methyl-3-buten-2-ol and 99%-(+)-ipsdienol as major components, and (−)-cis-verbenol, (−)-trans-verbenol, myrtenol and 2-phenyl ethanol as minor or trace components. The release of these male-produced compounds was confirmed by the analysis on aeration sample of an I. shangrila infested wind-thrown spruce trunk. The quantities of 2-methyl-3-buten-2-ol, cis-verbenol and trans-verbenol from male hindgut extracts were almost unchanged or even slightly increased during gallery development, while ipsdienol decreased dramatically after mating with three females. No obvious Ips-related aggregation pheromone components were detected in the female hindgut extract. A field trapping bioassay in Qinghai, China, showed that the ternary blends containing 2-methyl-3-buten-2-ol, (−)-cis-verbenol and 97%-(+)-ipsdienol or (±)-ipsdienol, caught significantly more I. shangrila (♂:♀ = 1:2.14) than did the unbaited control. Replacing 97%-(+)-ipsdienol (close to the naturally produced enantiomeric ratio) with (±)-ipsdienol in the ternary blend seemed to reduce trap catches by 50%, but the difference was not statistically significant. Surprisingly, addition of (−)-trans-verbenol (at 0.2 mg/day) to the active ternary blends significantly reduced traps catches to the level not different from the unbaited control. Our results suggest that the two major components, 2-methyl-3-buten-2-ol and 99%-(+)-ipsdienol, plus a minor component, (−)-cis-verbenol, produced by fed males, are likely the aggregation pheromone components of I. shangrila.     

腐殖酸对水中多壁碳纳米管凝聚特性的影响

以多壁碳纳米管(MWNTs)稳定悬浮液为对象,研究了腐殖酸(HA)对水中MWNTs凝聚特性的影响.结果表明,采用SDS超声分散法制备的MWNTs稳定悬浮液具有较强的稳定性,投加电解质可通过压缩双电层机制使其发生凝聚,并符合经典的DLVO理论.HA存在时,可通过增大MWNTs颗粒间的空间位阻效应和亲水性,抑制凝聚反应发生,从而提高其在水中的稳定性.Ca2+可与HA发生络合桥联作用,导致MWNTs颗粒粒径的大幅提高,强化凝聚发生.水中MWNTs的分散和凝聚性质将受到有机物性质和电解质种类等复杂因素的影响.