退田还湖对洞庭湖生态环境的影响

在总结围湖造田带来的生态环境影响的基础上,就退田还湖工程对洞庭湖生态环境的影响进行了分析,获得了退田还湖能扩大洞庭湖的蓄洪能力、改善湖泊局地气候和水质、有利于生物多样性保护和水资源的可持续利用,同时指出了移民集中建镇安置可能带来的水质污染风险,并提出了湖泊生态环境保护的建议与对策。     

Effects of the litter layer of Pteridium aquilinum on seed banks under experimental restoration

Questions: Does the litter layer of Pteridium aquilinum (bracken) act as a barrier to certain species in the seed bank? Does bracken control/restoration treatment affect seed transfer through the litter layer? Location: Five experiments at three sites across the UK covering two major vegetation types; acid‐grassland and heath‐land. Methods: At each experiment a range of bracken control and vegetation restoration treatments were applied for about ten years. The seed bank was sampled in both the bracken litter and the soil. The cover (%) of each species in the vegetation and the bracken litter abundance (cover and depth) was also estimated. Results: The bracken litter layer acts as an inert barrier as it contained a large proportion of seeds available in the litter‐soil profile (38%– 67% of the total). Bracken litter depth and cover also influenced significantly the seed bank composition in both the bracken litter and the soil. These effects were site‐specific, and species‐specific. The application of treatments changed significantly the balance between seed inputs and outputs in the bracken litter layer for some species. This was either a positive or negative response relative to the untreated control plots. Conclusion: For heathland and acid‐grassland restoration, the bracken litter layer may be an important seed source, but it must be disturbed particularly before seed addition.     

Existence d''une phéromone sexuelle chezCaryedon serratus: Attractivité des femelles et réactivité des males

Résumé Les femelles deCaryedon serratus (Ol.) produisent, pendant la scotophase, une phéromone sexuelle volatile qui déclenche chez les males une chémoanémotaxie positive. Les effets de l'age sur l'attractivité des femelles et sur la réactivité des males ont été étudiés. Plus de soixante-dix pour cent des males commencent à réagir à la phéromone sexuelle dès les premières 24 heures qui suivent leur émergence. Une seule femelle sur 31 a été attractive à cet age. A 48 heures, le pourcentage des femelles attractives est de 38,7%. Il existe une variabilité inter et intra femelles dans la production de phéromone sexuelle (début, régularité). L'existence des récepteurs antennaires à la phéromone sexuelle chez le male est montrée par des études électrophysiologiques (EAG). La variabilité de la production de phéromone sexuelle est discutée.

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Summary The female ofCaryedon serratus release, from the beginning of scotophase, a sex pheromone witch triggers a positive chemoanemotaxy in males. The effects of age on female attractiveness and on male reactivity are studied. About 70.37% of males begin to react to the sex pheromone within the first 24 h after emergence. At this age, only one female out of 31 is attractive. At 48 h, the percentage of attractive females is 38.7%. There is inter and intra-female variation in sex pheromone production (beginning, regularity). The existence of receptors on male antennae for this pheromone is shown by electrophysiology (EAG). The variability in sex pheromone production is discussed.

     

德兴铜矿矿山废弃地植被恢复与重建研究

对德兴铜矿1号尾矿库库面纯尾砂立地植被恢复与重建进行了研究。结果表明：纯尾砂植被恢复与重建的主要是土壤因子,即土壤组成、结构、水分、养分和毒性。矿区自然植被的次生演替序列为：次生裸地→草丛→灌丛→针叶林→常绿与落叶阔叶混交林、针阔叶混交林→常绿阔叶林6个阶段。纯尾砂立地13种试验先锋草种的优劣热比较结果依次顺序为：水蜡烛1．06＞假俭草1．05＞苇状羊茅1．01＞芒草1．00＝弯叶画眉草1．00＞狗牙根0．98＝百喜草0．98＝香根草0．98＞象草0．87＞荩草0．85＞矮象草0．74＞节节草0．73＞苏丹草0．55。水蜡烛、假俭草、苇状羊茅、芒草、弯叶画眉草、狗牙根、百喜草、香根草、象草、荩草、矮象草、节节草被认为是纯尾砂植被恢复与重建的优良先锋草种。纯尾砂立地植被恢复与重建的途径主要包括植被恢复演替、土壤生物改良和客土复垦3种模式。     

Dinosaur footprints from the Early Jurassic of Le Mazel (Lozère,Southern France)

During the 20^th century, the first dinosaur tracks of the Causses Basin were identified at Saint-Laurent-de-Trèves, in the Parc National des Cévennes (southern France). A recent excavation reveals a new theropod tracksite in the Hettangian deposits from Le Mazel, 2 km from the historical tracksite at Saint-Laurent-de-Trèves. The tracks are here described combining a biometric approach and 3D imaging photogrammetry. The main track-bearing surface bears 64 in situ tridactyl footprints preserved as concave epireliefs. Two morphotypes were identified, a “Grallatorid” morphotype and a “Kayentapus” morphotype. Footprints belonging to the first morphotype are closely similar to Grallator lescurei, Grallator minusculus, and Grallator sauclierensis. This study shows the difficulty to distinguish quite similar tridactyl tracks from an ichnotaxonomic point of view and highlights the importance of detailed biometric comparisons. Tracks are preserved in a brown to yellowish dolomudstone showing abundant cryptalgal laminites and mud cracks. These deposits were accrued in shallow environments such as intertidal and supratidal zones of a tidal flat.     

脊髓5—HT1A受体和5HT3受体参与的心血管反应

给清醒大鼠脊髓蛛网膜下腔注射(ith)5-羟色胺(5-HT)1.56、3.125、6.25和12.5μg/1Oμl后引起明显血压升高,并呈量效关系,但心率(HR)无明显改变。Ith 5-HT 再摄取抑制剂 fluoxetine(10μg/10μ1)后也使平均动脉压(mABP)明显上升,这一效应可被5-HT 受体阻断剂肉桂硫胺(cinanserin 25μg/1Oμl)完全阻断。8-OH-DPAT 和2-Methylhydroxy-tryptamine 分别为5-HT_(1A)受体和5-HT_3受体的激动剂,在 ith 8-OH-DPAT(2.5,5.0,1Oμg/1Oμl)后 mABP 明显上升,但 HR 减慢;相反,ith 2-Methylhydroxytryptamine 之后则使 mABP 明显降低,HR 无明显变化。以上结果表明,脊髓中5-HT 可通过激活5-HT_(1A)受体引起血压升高,激活5-HT_3受体则引起血压降低。这一发现对有关5-HT 中枢效应的不同报道提出了一种可能的解释。     

Influence de l'intensité et de la longueur d'onde de la lumière sur le rendement des radicaux libres dans les semences de tomate et de carotte

Influence of light intensity and wavelength on the yield of free radicals in seeds of tomato and carrot.
Seeds of tomato ( Lycopersicum esculentum L. cv. Gribovsky-1180) and carrot ( Daucus carota L. cv. Santanet) were irradiated by continuous light of different wavelengths (white, blue, green, red, far-red and He-Ne laser) and different power density. Free radical output was measured using Electron Spin Resonance spectra (ESR). The dependence of the content of free radicals (FR) on the light power density was established. The yield of FR in the seeds irradiated with monochromatic light of the same power density was inversely proportional to the wavelength. The ESR spectra showed maximum absolute number of FR for white light. Successive irradiations gave cumulative effects on the output of free radicals in both directions: increase by the action of white light and decrease by the action of red and far-red light. The contact of irradiated seeds with steam decreased the amount of FR.     

Hidden termite coprolites revealed by Synchrotron microtomography inside Eocene–Oligocene filled wood-borings from the Malzieu Basin,Lozère,southern France

Fragments of filled wood-borings were recently discovered from the Eocene–Oligocene Conglomerate and Sandstone Formation of the Malzieu Basin (Lozère, southern France). Propagation phase-contrast X-ray synchrotron microtomography (PPC-SRμCT) was used to characterize their hidden inner structures. Virtual 2D sections and 3D reconstructions show that the inner microstructures of borings display a mudstone–wackestone siliceous matrix including tiny coprolites. The hexagonal cross-section of these coprolites is characteristic of termite faecal pellets. Morphology and dimensions of the coprolites share strong similarities with those of extant Kalotermitidae (drywood termites). The depositional environment is interpreted as a fluvial valley in which the lenticular sandstone and conglomerate lenses correspond to channels. This discovery complements the record of Palaeogene termites which remain poor in France and throughout the world.     

The impact of translocations on neutral and functional genetic diversity within and among populations of the Seychelles warbler

Translocations are an increasingly common tool in conservation. The maintenance of genetic diversity through translocation is critical for both the short‐ and long‐term persistence of populations and species. However, the relative spatio‐temporal impacts of translocations on neutral and functional genetic diversity, and how this affects genetic structure among the conserved populations overall, have received little investigation. We compared the impact of translocating different numbers of founders on both microsatellite and major histocompatibility complex (MHC) class I diversity over a 23‐year period in the Seychelles warbler (Acrocephalus sechellensis). We found low and stable microsatellite and MHC diversity in the source population and evidence for only a limited loss of either type of diversity in the four new populations. However, we found evidence of significant, but low to moderate, genetic differentiation between populations, with those populations established with fewer founders clustering separately. Stochastic genetic capture (as opposed to subsequent drift) was the main determinant of translocated population diversity. Furthermore, a strong correlation between microsatellite and MHC differentiation suggested that neutral processes outweighed selection in shaping MHC diversity in the new populations. These data provide important insights into how to optimize the use of translocation as a conservation tool.     

Metabolic and photosynthetic consequences of blocking starch biosynthesis in the green alga Chlamydomonas reinhardtii sta6 mutant

Upon nutrient deprivation, microalgae partition photosynthate into starch and lipids at the expense of protein synthesis and growth. We investigated the role of starch biosynthesis with respect to photosynthetic growth and carbon partitioning in the Chlamydomonas reinhardtii starchless mutant, sta6, which lacks ADP‐glucose pyrophosphorylase. This mutant is unable to convert glucose‐1–phosphate to ADP‐glucose, the precursor of starch biosynthesis. During nutrient‐replete culturing, sta6 does not re‐direct metabolism to make more proteins or lipids, and accumulates 20% less biomass. The underlying molecular basis for the decreased biomass phenotype was identified using LC–MS metabolomics studies and flux methods. Above a threshold light intensity, photosynthetic electron transport rates (water → CO₂) decrease in sta6 due to attenuated rates of NADPH re‐oxidation, without affecting photosystems I or II (no change in isolated photosynthetic electron transport). We observed large accumulations of carbon metabolites that are precursors for the biosynthesis of lipids, amino acids and sugars/starch, indicating system‐wide consequences of slower NADPH re‐oxidation. Attenuated carbon fixation resulted in imbalances in both redox and adenylate energy. The pool sizes of both pyridine and adenylate nucleotides in sta6 increased substantially to compensate for the slower rate of turnover. Mitochondrial respiration partially relieved the reductant stress; however, prolonged high‐light exposure caused accelerated photoinhibition. Thus, starch biosynthesis in Chlamydomonas plays a critical role as a principal carbon sink influencing cellular energy balance however, disrupting starch biosynthesis does not redirect resources to other bioproducts (lipids or proteins) during nutrient‐replete culturing, resulting in cells that are susceptible to photochemical damage caused by redox stress.