A new parasitic isopod of the genus Norileca (Crustacea, Cymothoidae) from the Arabian Sea

A new species Norileca borealis belonging to the family Cymothoidae is described in detail and illustrated. The new species is distinguished from the other members of the genus by the details of maxilla 2, maxilliped, pleotelson and pereopod 1.

中国卧龙自然保护区不同海拔川滇高山栎(Quercus aquifolioides)群体的遗传变异

海拔梯度造成的环境异质性，如崎岖的地形、复杂的植被结构以及花期延迟等可能会极大地影响到物种的形态和遗传变异格局。理解物种形态和遗传变异的海拔格局对于物种多样性的管理和保护是非常重要的。尽管植物群体遗传学是一个飞速发展的研究领域，然而与海拔相关的形态变异、遗传变异及群体间遗传差异的研究却很少。到目前为止，还不清楚遗传变异与海拔之间是否必然的相关性。 川滇高山栎是一种重要的生态和经济型树种，广泛分布于中国西南的四川、西藏、贵州和云南省的高海拔地区，在保持水土、调节气候方面起着十分重要的作用。尽管主要受阳光限制而仅分布于阳坡，但其海拔梯度范围较大，表明川滇高山栎对不同的环境具有很强的适应性。本文通过叶型及生理响应、微卫星分子标记和扩增性片段长度多态性方法，试图探索川滇高山栎叶沿海拔梯度的形态和生理响应及其沿海拔梯度的遗传变异格局，为川滇高山栎的保护和利用提供进一步的遗传学理论依据和技术指导。 对叶形、含氮量及碳同位素的试验结果表明，平均比叶面积、气孔密度、气孔长度和气孔指数等气孔参数随海拔的升高呈非线性变化。在海拔大于2800 m时，川滇高山栎的比叶面积、气孔长度和气孔指数都随海拔升高而降低，但是在海拔小于2800 m时，这些指标都随海拔的升高而增大。相对而言，单位叶面积的含氮量和碳同位素则表现出相反的变化模式。另外，比叶面积是决定碳同位素沿海拔梯度变化的最重要参数。本研究结果表明，海拔2800 m附近是川滇高山栎生长和发育的最适地带，在这里生长的植物叶片厚度更薄、气孔更大、叶碳同位素值更小。 利用六对微卫星引物对五个不同海拔川滇高山栎群体遗传多样性进行研究，结果表明，群体内表现出较高的遗传多样性，平均每位点等位基因数11.33个，平均期望杂合度达0.820。群体间差异较小，分化仅为6.6％。聚类分析也并没有显示出明显的海拔格局。然而低频率等位基因却与海拔呈显著性正相关(R2=0.97, P < 0.01)，表明在高海拔处，川滇高山栎以更多的稀有基因来适应恶劣的环境条件。本试验结果表明由海拔梯度形成的选择性压力对川滇高山栎群体的遗传变异影响并不明显。 为了进一步探讨川滇高山栎群体遗传变异与海拔之间的相互关系，我们还对其进行了扩增性片段长度多态性分析。结果表明：(1)随海拔的升高(从群体WL2到群体WL5)，群体内遗传变异降低，而群体间遗传差异增加；(2)低海拔群体WL1表现出最低的遗传变异性(HE = 0.181)，同时与其余四个群体间呈现出最大的遗传差异性(平均FST = 0.0596)；(3)在除去低海拔群体WL1后，Mantel检测表明群体间遗传距离与海拔距离之间表现出正相关性。另外，研究结果还表明，遗传变异受生境条件(过度的湿热环境)及人为干扰(火烧、砍伐和放牧)的影响，这一点至少在低海拔群体WL1上发生了作用。 通过叶形态、生理及DNA分子水平的研究，结果表明叶形态特征和碳同位素与海拔紧密相关，与海拔之间呈非线性变化，海拔2,800 m附近是川滇高山栎生长和发育的最适地带。海拔梯度在一定程度上会影响到川滇高山栎群体的遗传变异结构，但在这样一个狭窄的地理分布区域里，这种影响并不足以导致群体间较大的遗传分化。同时生境条件及人为干扰也是影响遗传变异的限制性因子，不容忽视。 Altitudinal gradients impose heterogeneous environmental conditions, such as rugged topography, a complex pattern of vegetation and flowering delay, and they likely furthermore markedly affect the morphological and genetic variation pattern of a species. Understanding altitudinal pattern of morphological and genetic variation at a species is important for the management and conservation of species diversity. Although plant population genetics is a fast growing field of research, there are only few recent investigations, which analyzed the genetic differentiation and changes of intra-population variation along altitudinal gradients. At present, it is still unclear whether there are some common patterns of morphological and genetic variation with altitude. Quercus aquifolioides Rehder & E.H. Wilson, which is an important ecological and economical endemic woody plant species, is widely distributed in the Yunnan and Sichuan provinces, Southwest China. Its large range of habitat across different altitudes implies strong adaptation to different environments, although it is mainly restricted to sunny, south facing slopes. It plays a very important role in preventing soil erosion, soil water loss and regulating climate, as well as in retaining ecological stability. In this paper, we tried to understand the altitudinal pattern of morphological and genetic variation along altitudinal gradients through the experiments of leaf morphological and physiological responses, microsatellite analysis and AFLP markers. In leaf morphological and physiological responses experiment, we measured leaf morphology, nitrogen content and carbon isotope composition (as an indicator of water use efficiency) of Q. aquifolioides along an altitudinal gradient. We found that these leaf morphological and physiological responses to altitudinal gradients were non-linear with increasing altitude. Specific leaf area, stomatal length and index increased with increasing altitude below 2,800 m, but decreased with increasing altitude above 2,800 m. In contrast, leaf nitrogen content per unit area and carbon isotope composition showed opposite change patterns. Specific leaf area seemed to be the most important parameter that determined the carbon isotope composition along the altitudinal gradient. Our results suggest that near 2,800 m in altitude could be the optimum zone for growth and development of Q. aquifolioides, and highlight the importance of the influence of altitude in research on plant physiological ecology. Genetic variation and differentiation were investigated among five natural populations of Q. aquifolioides occurring along an altitudinal gradient that varied from 2,000 to 3,600 m above sea level in the Wolong Natural Reserve of China, by analyzing variation at six microsatellite loci. The results showed that the populations were characterized by relatively high intra-population variation with the average number of alleles equaling 11.33 per locus and the average expected heterozygosity (HE) being 0.779. The amount of genetic variation varied only little among populations, which suggests that the influence of altitude factors on microsatellite variation is limited. However, there is a significantly positive correlation between altitude and the number of low-frequency alleles (R2=0.97, P < 0.01), which indicates that Q. aquifolioides from high altitudes has more unique variation, possibly enabling adaptation to severe conditions. F statistics showed the presence of a slight deficiency of heterozygosity (FIS=0.136) and a low level of differentiation among populations (FST=0.066). The result of the cluster analysis demonstrates that the grouping of populations does not correspond to the altitude of the populations. Based on the available data, it is likely that the selective forces related to altitude are not strong enough to significantly differentiate the populations of Q. aquifolioides in terms of microsatellite variation. To further elucidate genetic variation pattern of Q. aquifolioides populations under sub-alpine environments, genetic variation and differentiation were investigated along altitudinal gradients using AFLP markers. The altitudinal populations with an average altitude interval of 400 m, i.e. WL1, WL2, WL3, WL4 and WL5, correspond to the altitudes 2,000, 2,400, 2,800, 3,200 and 3,600 m, respectively. Our results were as follows: (i) decreasing genetic variation (ranging from 0.253 to 0.210) and increasing genetic differentiation with altitude were obtained from the WL2 to the WL5 population; (ii) the WL1 population showed the lowest genetic variation (HE = 0.181) and the highest genetic differentiation (average FST = 0.0596) with the other four populations; (iii) the positive correlation was obtained using Mantel tests between genetic and altitude distances except for the WL1 population. Our results suggest that altitudinal gradients may have influenced the genetic variation pattern of Q. aquifolioides populations to some extent. In addition, habitat environments (unfavorable wet and hot conditions) and human disturbances (burning, grazing and felling) were possible influencing factors, especially to the low-altitude WL1 population. The present study shows that there were close correlations between morphological features and carbon isotope composition in our data. This indicates that a coordinated plant response modified these parameters simultaneously across different altitudes. Around 2,800 m altitude there seems to be an optimum zone for growth and development of Q. aquifolioides, as indicated by thinner leaves, larger stomata and more negative d13C values. All available evidence indicates altitudinal gradients may have influenced the genetic variation pattern of Q. aquifolioides to some extent. Decreasing genetic variation and increasing genetic differentiation with altitude was obtained except for the WL1 population. And the environment of habitats and human disturbances were also contributing factors, which impact genetic variation pattern, especially to the low-altitude WL1 population.

中国蜡革菌属的研究(英文)

介绍了蜡革菌属Ceraceomyces及该属在中国的种类,其中北方蜡革菌Ceraceomyces borealis是中国新记录种,根据中国的材料对其进行了详细的描述和显微结构绘图,同时给出了中国蜡革菌属5个种的检索表。

Distribution of molluscan remains in the sediment of the Chukchi Sea and its vicinity, the Arctic

The result of an analysis of mollusca remains collected from the Chukchi Sea, Beaufort Sea and Bering Sea in the First Chinese National Arctic Research Expedition, from July to September, 1999 is presented. Seventeen species of mollusca have been identified, which belong to two classes: Bivalvia and Gastropoda. The compositions of the mollusca are very simple. According to the distribution pattern two groups may be distinguished among molluscan species. The Pan-Arctic and circumboreal group comprises Nuculana pernula, N.radiata, Nucula bellotii, Astarte montagui, Seripes groenlandicus, Macoma calcarea, M. moesta alaskana, Liocyrna fluctuosa, Mya pseudoarenaria and Turritella polaris. Three species, Cyclocardia crebricostata, Trichotrois coronata and Argobuccinum oregonense are components of the Pan-Arctic and Pacific boreal group. With regard to feeding habits, detritus feeders dominate. There are 7 species of detritus feeders, i.e., Nuculana pernula, N. radiata, Nucula bellotii, Macoma calcarea, M. moesta alaskana, Macoma sp. and Trichotropis coronata. Detritus feeders are dominant with regard to the numbers of species as well as to the frequency of occurrence. Macoma calcarea is the most abundant species.

中国北方石墨矿床及赋矿孔达岩系碳同位素特征及有关问题讨论

本文综合了中国北方孔达岩系和石墨矿床的碳同位素数据102件, 发现片麻岩石墨n 透辉岩石墨< 大理岩石墨<石墨大理岩方解石< 大理岩方解石; 混合岩化岩石中石墨D13C 总介于有机碳和无机碳之间; 不同地体片麻岩石墨D13C 极为一致, 变化于- 22. 8‰～ - 21. 48‰, 略低于世界有机质平均值- 26 ±7‰; 大理岩的原岩碳酸盐D13C 高于2‰, 与2330～ 2060Ma期间全球性D13Ccarb 正向漂移事件一致。地质流体是碳同位素分馏、均一化的重要因素, 是石墨矿床的3种主要碳源之一, 是碳的5 种存在形式之一, 也是碳循环的重要媒介和方式; 导致热液矿床D13C= - 5‰左右的因素较多, 依据D13Ccalciteµ - 5‰得出成矿物质和流体来自地幔的结论值得怀疑; 中国北方孔达岩系形成于古元古代, 可能为2300～ 2050Ma。

喀斯特山区植物碳同位素组成特征及其对水分利用效率的指示——以贵州花溪杨中小流域为例

测定了贵州喀斯特山区灌丛12 种主要植物叶片的D13C 值, 研究了植物叶片碳同位素组成特征, 并分析了植物的水分利用效率。结果表明: 该区植物叶片的碳同位素组成的变化范围为- 26. 98‰～ - 29. 15‰, 平均值为- 28. 14‰。研究区D13C 值的分布相对均匀, 除高于我国热带雨林区植物外, 低于其它地区。此外, 植物的碳同位素组成存在较大的种间差异, 生境的变化对植物的碳同位素组成有着一定的影响, 但不同植物种对生境的响应不同。植物的D13C 值从生长初期到末期有降低的趋势, 但不同植物种的变化趋势存在差异。植物D13C 值随海拔的增加而增大, 但不同植物种D13C 值随海拔增加的程度存在差异。不同植物种之间的水分利用效率不同, 相同植物种在不同的生境条件下其水分利用效率也有差异。植物生长初期的水分利用效率要比后期的高; 高海拔处植物水分利用效率要比低海拔处植物的高。

Ice-binding proteins adsorb to their ligand via anchored clathrate waters

The main success of my thesis has been to establish the mechanism by which antifreeze proteins (AFPs) bind irreversibly to ice crystals, and hence prevent their growth. AFPs organize ice-like water on their ice-binding site, which then merges and freezes with the quasi-liquid layer of ice. This was revealed from studying the exceptionally large (ca. 1.5-MDa) Ca 2+-dependent AFP from the Antarctic bacterium Marinomonas primoryensis (MpAFP). The 34-kDa antifreeze- active region of MpAFP was predicted to fold as a novel Ca 2+-binding β-helix. Site-directed mutagenesis confirmed the model and demonstrated that its ice-binding site (IBS) consisted of solvent-exposed Thr and Asx parallel arrays on the Ca 2+-binding turns. The X-ray crystal structure of the antifreeze region was solved to a resolution of 1.7 Å. Two of the four molecules within the unit cell of the crystal had portions of their IBSs freely exposed to solvent. Identical clathrate-like cages of water molecules were present on each IBS. These waters were organized by the hydrophobic effect and anchored to the protein via hydrogen bonds. They matched the spacing of water molecules in an ice lattice, demonstrating that anchored clathrate waters bind AFPs to ice. This mechanism was extended to other AFPs including the globular type III AFP from fishes. Site-directed mutagenesis and a modified ice-etching technique demonstrated this protein uses a compound ice-binding site, comprised of two flat and relatively hydrophobic surfaces, to bind at least two planes of ice. Reinvestigation of several crystal structures of type III AFP identified anchored clathrate waters on the solvent-exposed portion of its compound IBS that matched the spacing of waters on the primary prism plane of ice. Ice nucleation proteins (INPs), which can raise the temperature at which ice forms in solution to just slightly below 0oC, have the opposite effect to AFPs. A novel dimeric β-helical model was proposed for the INP produced by the bacterium Pseudomonas borealis. Molecular dynamics simulations showed that INPs are also capable of ordering water molecules into an ice- like lattice. However, their multimerization brings together sufficient ordered waters to form an ice nucleus and initiate freezing.

Forest fires and insects: palaeoentomological research from a sub-fossil burnt forest.

The role of fire within Pinus-mire ecosystems is explored by focusing on a palaeoentomological investigation of the extensive burnt fossil forest preserved within the basal deposits of the raised mires of Thorne and Hatfield Moors, Humberhead Levels, eastern England. Remains of charred tree macrofossils (roots, stumps and trunks) are widely distributed across both sites, mainly comprising Pinus and Betula. Evidence from this research and elsewhere suggest fires were a common event on Pinus mires, and may indicate that such episodes played an important role in the development of raised bogs. A fire-loving (pyrophilous) insect fauna appears to have been attracted to the burnt areas and the decline and extirpation in Britain of a number of pyrophilous species (e.g. Stagetus borealis Isrealsson) suggests the former importance of this type of habitat within British Pinus-mire systems. The lack of consideration given to the role of natural fires within the British landscape is questioned and the interpretation of charcoal within mire deposits as a possible anthropogenic indicator is highlighted as an area that would benefit some reconsideration.

Holocene deposits from Neptune’s Cave, Nordland, Norway: Environmental interpretation and relation to the deglacial and emergence history of the Velfjord–Tosenfjord area

Neptune’s Cave in the Velfjord–Tosenfjord area of Nordland, Norway is described, together with its various organic deposits. Samples of attached barnacles, loose marine molluscs, animal bones and organic sediments were dated, with radiocarbon ages of 9840+/-90 and 9570+/-80 yr BP being derived for the barnacles and molluscs, based on the superseded but locally used marine reservoir age of 440 years. A growth temperature of c. 7.51C in undiluted seawater is deduced from the d13C and d18O values of both types of marine shell, which is consistent with their early Holocene age. From the dates, and an assessment of local Holocene uplift and Weichselian deglaciation, a scenario is constructed that could explain the situation and condition of the various deposits. The analysis uses assumed local isobases and sea-level curve to give results: that are consistent with previous data, that equate the demise of the barnacles to the collapse of a tidewater glacier in Tosenfjord, and that constrain the minimum extent of local Holocene uplift. An elk fell into the cave in the mid-Holocene at 510070 yr BP, after which a much later single ‘bog-burst’ event at 178070 yr BP could explain the transport of the various loose deposits further into the cave.

High-resolution 14C dating of a 25,000-year lake-sediment record from equatorial East Africa

We dated a continuous, ~22-m long sediment sequence from Lake Challa (Mt. Kilimanjaro area, Kenya/Tanzania) to produce a solid chronological framework for multi-proxy reconstructions of climate and environmental change in equatorial East Africa over the past 25,000 years. The age model is based on a total of 168 AMS 14C dates on bulk-organic matter, combined with a 210Pb chronology for recent sediments and corrected for a variable old-carbon age offset. This offset was estimated by i) pairing bulk-organic 14C dates with either 210Pb-derived time markers or 14C dates on grass charcoal, and ii) wiggle-matching high-density series of bulk-organic 14C dates. Variation in the old-carbon age offset through time is relatively modest, ranging from ~450 yr during glacial and late glacial time to ~200 yr during the early and mid-Holocene, and increasing again to ~250 yr today. The screened and corrected 14C dates were calibrated sequentially, statistically constrained by their stratigraphical order. As a result their constrained calendar-age distributions are much narrower, and the calibrated dates more precise, than if each 14C date had been calibrated on its own. The smooth-spline age-depth model has 95% age uncertainty ranges of ~50–230 yr during the Holocene and ~250–550 yr in the glacial section of the record. The d13C values of paired bulk-organic and grass-charcoal samples, and additional 14C dating on selected turbidite horizons, indicates that the old-carbon age offset in Lake Challa is caused by a variable contribution of old terrestrial organic matter eroded from soils, and controlled mainly by changes in vegetation cover within the crater basin.

The anomaly in the candidate microlensing event PA-99-N2

The light curve of PA-99-N2, one of the recently announced microlensing candidates toward M31, shows small deviations from the standard Paczynski form. We explore a number of possible explanations, including correlations with the seeing, the parallax effect, and a binary lens. We find that the observations are consistent with an unresolved red giant branch or asymptotic giant branch star in M31 being microlensed by a binary lens. We find that the best-fit binary lens mass ratio is similar to1.2x10(-2), which is one of the most extreme values found for a binary lens so far. If both the source and lens lie in the M31 disk, then the standard M31 model predicts the probable mass range of the system to be 0.02-3.6 M-circle dot (95% confidence limit). In this scenario, the mass of the secondary component is therefore likely to be below the hydrogen-burning limit. On the other hand, if a compact halo object in M31 is lensing a disk or spheroid source, then the total lens mass is likely to lie between 0.09 and 32 M-circle dot, which is consistent with the primary being a stellar remnant and the secondary being a low-mass star or brown dwarf. The optical depth (or, alternatively, the differential rate) along the line of sight toward the event indicates that a halo lens is more likely than a stellar lens, provided that dark compact objects comprise no less than 15% (or 5%) of halos.