内蒙古大庙中新世小哺乳动物化石埋藏学研究

捕食是小哺乳动物死亡最常见的原因,也导致被捕食动物遗骸发生明显改变.动物死亡后的风化、踩踏、搬运等过程也会改变动物的骨骼并影响到化石组合的形成.本文研究了内蒙古大庙三个中新世化石地点,时代从早中新世到晚中新世早期(约21～11.6 Ma).通过分析各小哺乳动物化石组合的沉积背景以及埋藏学特征识别化石埋藏的主要成因.结果显示出捕食是三个地点小哺乳动物化石埋藏的基本成因,而在两个年轻的地点中也有流水搬运与可能的踩踏因素的叠加.三个地点可能存在不一样的捕食者:早中新世地点以猫头鹰捕食为主,中、晚中新世地点则以日间活动的鸟类或哺乳类为主要捕食者.研究还显示小哺乳动物的系统发掘是可行的,在一定程度上可以减少采样过程中产生的破坏.     

Stem wood properties of mature Norway spruce after 3 years of continuous exposure to elevated [CO2] and temperature

The objective of the study was to investigate the interactive effects of elevated atmospheric carbon dioxide concentration, [CO₂], and temperature on the wood properties of mature field-grown Norway spruce ( Picea abies (L.) Karst.) trees. Material for the study was obtained from an experiment in Flakaliden, northern Sweden, where trees were grown for 3 years in whole-tree chambers at ambient (365 μmol mol⁻¹) or elevated [CO₂] (700 μmol mol⁻¹) and ambient or elevated air temperature (ambient +5.6 °C in winter and ambient +2.8 °C in summer). Elevated temperature affected both wood chemical composition and structure, but had no effect on stem radial growth. Elevated temperature decreased the concentrations of acetone-soluble extractives and soluble sugars, while mean and earlywood (EW) cell wall thickness and wood density were increased. Elevated [CO₂] had no effect on stem wood chemistry or radial growth. In wood structure, elevated [CO₂] decreased EW cell wall thickness and increased tracheid radial diameter in latewood (LW). Some significant interactions between elevated [CO₂] and temperature were found in the anatomical and physical properties of stem wood (e.g. microfibril angle, and LW cell wall thickness and density). Our results show that the wood material properties of mature Norway spruce were altered under exposure to elevated [CO₂] and temperature, although stem radial growth was not affected by the treatments.     

Metabolism of Arginine and Ornithine in Suspension-Cultured Cells and Aseptic Roots of Intact Plants of Atropa belladonna

Suspension-cultured cells and aseptically cultured roots ofintact plants of Atropa belladonna L. removed tropane alkaloidprecursors arginine (Arg) and ornithine (Orn) at nearly an equalrate from the feeding medium. A great part of Arg- and Orn-derived¹⁴C-label was found in ethanol-insoluble compounds, mostly inproteins already after 2 h feeding. Ethanol-soluble label inthe roots was found mainly in amino acids (e.g. glutamine, Gln)after 2 h feeding, and after 20 h also in some intermediatesof the urea cycle (e.g. argininosuccinate). In suspension cultures, subculturing of the initiation callusdecreased both the uptake of the basic amino acids tested andtheir binding on to the apoplastic space. After 20 h feedingwith Arg more label was found in organic acids in stationaryphase suspension cultures with repressed alkaloid synthesisthan in roots producing alkaloids. The growth phase and passagenumber also affected into which amino acids the label was incorporated.When the initiation callus was young (the 3rd passage), theintermediates of the urea cycle were actively labelled, butwhen the initiation callus was older (the 8th passage) and thesuspension formed roots, especially Gln was labelled. Only tracesof -N-methylornithine were detected in feeding experiments withOrn and Arg. Considerable arginase activity with a high pH optimumwas observed in cell suspensions and roots of A. belladonna. Key words: Atropa, arginine, ornithine, roots, suspension culture     

Effects of Coyote Population Reduction on Swift Fox Demographics in Southeastern Colorado

ABSTRACT The distribution and abundance of swift foxes (Vulpes velox) has declined from historic levels. Causes for the decline include habitat loss and fragmentation, incidental poisoning, changing land use practices, trapping, and predation by other carnivores. Coyotes (Canis latrans) overlap the geographical distribution of swift foxes, compete for similar resources, and are a significant source of mortality amongst many swift fox populations. Current swift fox conservation and management plans to bolster declining or recovering fox populations may include coyote population reduction to decrease predation. However, the role of coyote predation in swift fox population dynamics is not well-understood. To better understand the interactions of swift foxes and coyotes, we compared swift fox population demographics (survival rates, dispersal rates, reproduction, density) between areas with and without coyote population reduction. On the Piñon Canyon Maneuver Site, Colorado, USA, we monitored 141 swift foxes for 65,226 radio-days from 15 December 1998 to 14 December 2000 with 18,035 total telemetry locations collected. Juvenile swift fox survival rate was increased and survival was temporarily prolonged in the coyote removal area. Adult fox survival patterns were also altered by coyote removal, but only following late-summer coyote removals and, again, only temporarily. Coyote predation remained the main cause of juvenile and adult fox mortality in both areas. The increase in juvenile fox survival in the coyote removal area resulted in a compensatory increase in the juvenile dispersal rate and an earlier pulse in dispersal movements. Adult fox dispersal rate was more consistent throughout the year in the coyote removal area. Coyote removal did not influence the reproductive parameters of the swift foxes. Even though juvenile survival increased, swift fox density remained similar between the areas due to the compensatory dispersal rate among juvenile foxes. We concluded that the swift fox population in the area was saturated. Although coyote predation appeared additive in the juvenile cohort, it was compensatory with dispersal.     

内蒙古大庙中中新世上猿化石地点的鼠兔科化石(英文)

鼠兔科虽然是地质历史时期较为繁盛的一个门类,但现在仅有一个属(鼠兔属Ochotona)。Ochotona被认为与Bellatona有密切的亲缘关系,可能是由后者衍生而来。详细描述了内蒙古大庙上猿化石地点发现的鼠兔科化石,识别出一种古老类型Desmatolagus moergenensis以及其他三个种Bellatona cf.B.forsythmajori,Bellatonoides eroli,Ochotonacf.O.lagreli。归入Bellatona,Bellatonoides和Ochotona的这三个种的p3具有相似的形态,并呈现出连续变化的特征。Bellatona的p3具有两个唇侧褶沟,但无舌侧褶沟;Bellatonoides的p3具有浅的舌侧前褶沟,但与唇侧前褶沟分开较宽;Ochotona的p3则具有深的舌侧前褶沟,与唇侧前褶沟之间仅以很窄的齿质桥连接。M2从无后突起、较小的后突起至发育的后突起,也呈现出连续变化的特征。中间颊齿则难以区分。因此,推测这三个种之间存在连续的线性演化关系,Ochotona可能直接起源于Bellatonoides。磁性地层学与生物地层学对比结果显示该地点的年代约为12Ma,与根据分子钟推测的Ochotona的分化时间基本一致。     

Characterization of the Proteinases Present in Germinating Seeds of Scots Pine, Pinus sylvestris

Methods were developed to determine proteinase activity in germinating seeds of Scots pine. The assays were based on the liberation of TCA-soluble peptides from haemoglobin at pH 3.7 and from casein at pH 5.4 and pH 7.0; the reaction products were determined by the Lowry method. — Endosperms separated from seeds at the time of rapid storage protein mobilization (seedling length between 20 and 50 mm) showed high proteinase activities in all three assays. Experiments with different inhibitors suggested that at least four enzymes were involved. One of the enzymes resembled mammalian and microbial pepsin-like acid proteinases: the pH optimum was 3.7 and the enzyme was inhibited by pepstatin.—The proteinase activities in the endosperms were high enough to account for the mobilization of the reserve proteins during germination. Moreover the activities at pH 3.7.5.4. and 7.0 in the endosperms were 10-, 25-, and 50-fold the corresponding activities in the growing seedlings (a “reference” tissue). Consequently, it seems that both the acid and neutral proteinases take part in the mobilization of storage proteins in the germinating seed.     

Wood properties of two silver birch clones exposed to elevated CO2 and O3

Effects of elevated carbon dioxide (CO₂) and ozone (O₃) on wood properties of two initially 7‐year‐old silver birch (Betula pendula Roth) clones were studied after a fumigation during three growing seasons. Forty trees, representing two fast‐growing clones (4 and 80), were exposed in open‐top chambers to the following treatments: outside control, chamber control, 2 × ambient [CO₂], 2 × ambient [O₃] and 2 × ambient [CO₂]+2 × ambient [O₃]. After the 3‐year exposure, the trees were felled and wood properties were analyzed. The treatments affected both stem wood structure and chemistry. Elevated [CO₂] increased annual ring width, and concentrations of extractives and starch, and decreased concentrations of cellulose and gravimetric lignin. Elevated O₃ decreased vessel percentage and increased cell wall percentage in clone 80. In vessel percentage, elevated CO₂ ameliorated the O₃‐induced decrease. In clone 4, elevated O₃ decreased nitrogen concentration of wood. The two clones had different wood properties. In clone 4, the concentrations of extractives, starch, soluble sugars and nitrogen were greater than in clone 80, while in clone 80 the concentrations of cellulose and acid‐soluble lignin were higher. Clone 4 also had slightly longer fibres, greater vessel lumen diameter and vessel percentage than clone 80, while in clone 80 cell wall percentage was greater. Our results show that wood properties of young silver birch trees were altered under elevated CO₂ in both clones, whereas the effects of O₃ depended on clone.