长白山北坡垂直植被带木本植物的植硅体形态特征及其环境意义

长白山垂直分布的植被是温带到寒带植被的组合,能够很好地反映温度变化趋势,研究其植物的植硅体对于了解长白山气候变迁有重要意义.作者选择长白山9科14属木本植物的叶子,采用湿式灰化法对其进行植硅体分析,计算了不同形态植硅体的百分含量,同时测量了长度和宽度.研究表明:长白山北坡垂直植被带中典型木本植物的叶子具有8种植硅体类型:表面有突起、皱纹的椭圆形、卵形;具有螺旋纹的纺锤状以及导管形、弓形、鸟嘴状、扁棒型、石块状、松树皮状、不确定型.在14种木本植物叶子中都出现了扁棒型植硅体,其含量随海拔升高逐渐增加,说明在长白山区扁棒型植硅体是示冷型植硅体.阔叶类木本植物叶子中,具有螺旋纹的纺锤体及导管形、弓形植硅体占优势;裸子植物叶子中松树皮状、石块状植硅体,其含量随海拔升高逐渐递减,说明松树皮状和石块状植硅体是示暖型植硅体.     

植硅体形态的研究进展

植硅体作为古环境的代用指标是以植硅体形态分类研究为基础的,植硅体分类研究程度将直接影响到植硅体应用的精度及深度。从植硅体的植物母体来源分析和讨论,分别总结和比较多种植物(21科的草本植物及20科的木本植物)科、属乃至种级水平上的典型植硅体类型,植硅体组合特征及同一类型植硅体的细微差别。综合多位学者的认识,以期能够完善植硅体形态学研究,为植硅体在现代植物分类、重建古环境、环境考古等领域提供有意义的证据和资料。     

东北地区草本植物和木本植物植硅体的形态特征鉴别分析

为了鉴别草本植物来源及木本植物来源的植硅体类型,本文从植硅体形态和大小两方面着手,对东北地区常见的57种草本植物和72种木本植物的植硅体进行系统分析。从植硅体形态来看,鞍型、帽型和哑铃型等24类植硅体为草本植物的特征类型,木本植物也鉴定出17类典型植硅体类型,包括立方体、端尖细长棒型和凹口棒型等。同时,进一步通过引入形态参数区分三类形态相似且含量较多的植硅体类型(不规则扁平状、边缘弯曲扁平状、不规则块状)的植物来源,结果显示,长度30μm不规则扁平状、长度50μm边缘弯曲扁平状(包含蕨类植物)、长度30μm不规则块状主要来源于草本植物;长度40μm不规则扁平状、长度50μm边缘弯曲扁平状及长度40μm不规则块状主要形成于木本植物。在利用形态和大小分别区分植硅体植物来源的基础上,本研究还系统总结了东北地区草本类植硅体和木本类植硅体的鉴别标准,并据此识别东北地区表土植硅体的植物来源。该研究能够为本区开展植硅体-古植被重建等研究提供重要的参考。     

玉米生长周期内植硅体的变化研究

植物不同组织部位的植硅体形态、组合研究有助于准确鉴定考古地层植硅体来源植物的具体种类以及组织部位;生长周期内植硅体形态、组合变化研究有利于探讨植硅体的形成机制,认识植硅体形态组合变化与环境因子之间的关系,科学解释土壤及沉积物植硅体古植被、古环境信息。玉米变种亚航0919在生长的初期,尤其是前3片真叶,含比重较高的3片以上的多铃型植硅体;随着玉米生长天数增加及生长温度的升高,第4—5片真叶3片以上多铃型植硅体消失,哑铃型植硅体含量逐渐增加,尖型及棒型植硅体含量有所降低,叶片哑铃型植硅体长度(L)及宽度(W)有增加的趋势;相同生长阶段,叶片与叶脉植硅体组合及大小显著不同,叶脉相对叶片含较低比重的哑铃型植硅体、较高比重的十字型和椭圆-哑铃型植硅体,叶脉中哑铃型植硅体小于叶片中的。玉米叶片植硅体形态、组合在生长季节内的变化主要与植物的成熟阶段及生长环境温度的变化有关,其植硅体形态、大小和组合,尤其是哑铃型植硅体大小能够响应温度变化。     

东北地区芦苇植硅体的变化特征

深入研究芦苇(Phragmites australis)不同生长期植硅体的形态变化规律, 对提高古植被重建精度、探讨植硅体形成机理具有重要意义。该文对东北地区12个样点的芦苇叶片进行研究, 选取长势相近、叶片大小一致的芦苇叶片, 用湿式灰化法提取植硅体并对其进行分类和命名。研究发现, 芦苇植硅体主要有5种类型, 在不同生长期内和不同温湿度组合下, 其植硅体类型组合基本无变化, 说明同种植物的植硅体类型组合具有稳定性, 据此可以有效地恢复古植被; 同时芦苇鞍型植硅体百分含量的峰值出现在7月份, 随后稍有减少, 而芦苇扇型植硅体百分含量和浓度的峰值出现在8或9月份, 谷值在7月份。由此推测芦苇鞍型植硅体的形成可能更多地受控于植物的光合作用和蒸腾作用, 芦苇扇型植硅体的形成可能与机动细胞的支撑作用关系密切。实验结果还表明芦苇植硅体浓度并不是随着时间逐渐积累的, 其在8月份达到峰值, 9月份达到谷值, 因此推测植物植硅体浓度的变化规律可能与植物在不同生长期其自身对硅的需求规律相一致。鞍型植硅体浓度的峰值也出现在8月份, 谷值也在9月份, 其浓度变化与芦苇植硅体总浓度的变化趋势相似。     

内蒙古典型草原禾本科植硅体形态

运用地层中植硅体组合解释过去草原植被及气候变化的关键之一,是要了解研究区现代植硅体形态及表土植硅体组合与现代植被的关系。文中研究内蒙古典型草原禾本科植物根、茎、叶、芒以及种子等不同部位的植硅体,对其中的12种主要禾本科植物叶表皮短细胞硅酸体进行分类及统计。研究表明：内蒙古典型草原禾本科叶表皮短细胞硅酸体可分为8种特殊形态类型。C3植物早熟禾亚科的叶表皮短细胞硅酸体形态多样。几乎所有早熟禾亚科都能产生圆型硅酸体,以贝加尔针茅(85．5％)、大针茅(89．7％)、克氏针茅(90％)以及芨芨草(96．6％)中的圆型硅酸体含量最丰富。针茅哑铃型主要见于针茅植物叶表皮短细胞中,克氏针茅的针茅哑铃型含量相对较高。羊草中未见针茅哑铃型硅酸体。浴草、披缄草叶表皮短细胞硅酸体以齿型为主,分别含87．3％和57．2％,齿型在硬质早熟禾中也占一定比例。沙生冰草中的脊圆型占优势,含74．4％。C3植物早熟禾亚科的叶表皮短细胞产生的截锥型硅酸体含量较少。C4植物虎尾草亚科中的糙隐子草叶表皮短细胞硅酸体以黍哑铃型、简单哑铃型、鞍型为主;黍亚科狗尾草则以黍哑铃型占优势(82．9％)。     

温带地区表土植硅体对温度的响应

植硅体的现代过程研究是利用植硅体这一指标精准恢复区域古植被、古气候的前提和关键环节,探讨表土植硅体组合的空间分布特征及其对环境因子的响应尤为重要.本研究在东北地区沿着年降水量为600 mm等降水线采集54块表土样品,研究单一温度控制下表土植硅体的空间分布规律,以期寻找对温度比较敏感的植硅体类型.结果表明:54块表土样品...     

内蒙古草原中东部现代表土植硅体组合与植被关系

对内蒙古中东部14个典型植被表土样品进行植硅体分析,同时将其结果作对应分析。结果表明：圆型和齿型在表土组合中占优势。圆型具有超代表性且在针茅草原和羊草草原表土组合中含量超过50％。针茅哑铃型和脊哑铃型在克氏针茅草原以及退化草原表土组合中含量偏高,可指示干的草原生境以及草原退化。蒿属块型表现为低代表性,即便是在冷蒿灌丛表土中,蒿属块型含量也较低。沙地云杉林和榆树灌丛生境特殊,它们的表土植硅体组合特征明显,前者以光滑块型、粗糙块型、规则多边型以及十字型等为主,后者以多铃型、三铃型、哑铃型以及简单哑铃型为特征。高山草甸和山杨林表土与研究区其它植被表土的相似性低。另外,研究区全新世古土壤剖面样品与表土样品的对应分析表明内蒙古中东部表土植硅体分析为恢复研究区全新世草原植被演化提供了参照物。     

青藏高原常见早熟禾亚科植硅体形态特征初步研究

文章对采自青藏高原地区早熟禾亚科（Pooideae）常见的10属19种现代植物进行详细的植硅体形态描述、分类、统计、测量和对比。分析发现：青藏高原现生植物早熟禾亚科（Pooideae）特有的植硅体形态主要包括帽型、齿型、针茅哑铃型和针茅多铃型,同时发育塔型、棒型、尖型、刺球型等其它亚科常见的类型。初步明确了部分属一级的植硅体形态特点,例如,羊茅属（Festuca）、早熟禾属（Poa）等主要发育尖顶帽型;长芒草（Stipa bungeana Trin．）、赖草（Leymus secalinus（Georgi）Tzvel．）等主要发育平顶帽型;针茅属（Stipa）主要发育针茅哑铃型;早熟禾属（Poa）、三毛草属（Trisetum）同时发育较丰富的帽型和齿型。为进一步地深入研究该区草原植被群落的演替过程和规律提供了植硅体形态学分析的基础。     

安徽禹会村遗址双墩文化时期农业发展的植硅体证据

本文利用植硅体分析方法,对安徽蚌埠禹会村遗址双墩文化时期44份土壤样品开展植物考古研究,重点关注典型农作物植硅体类型及其形态特征,以及敏感型与固定型植硅体组合特征等。结果显示,禹会村遗址大部分样品中皆发现有水稻特征型植硅体,并未发现粟、黍等旱地作物遗存;水稻扇型及双峰型植硅体形态特征分析显示,水稻遗存为驯化程度较高的粳型稻。以上研究结果表明,该遗址双墩文化时期的农业结构延续了顺山集文化时期以来种植粳型稻为主的传统。此外,通过水稻植硅体高密度样品中敏感型与固定型植硅体含量比值为0.7±0.2推测,该遗址水稻栽培环境属于“高地势-雨水供给”或“低地势-雨水供给”类型。本文研究结果为探讨淮河中游地区新石器时代农业发展、水稻栽培与驯化以及人类适应策略等问题提供了重要科学依据。     

CHANCE,PURPOSE, AND PROGRESS IN EVOLUTION AND CHRISTIANITY

Evolutionary biology has a complex relationship with ideas of chance, purpose, and progress. Probability plays a subtle role; strikingly, founding figures in statistics were motivated by evolutionary questions. The findings of evolutionary biology have been used both in support of narratives of progress, and in their deconstruction. Likewise, professional biologists bring to their scientific work a set of preconceptions about chance and progress, grounded in their philosophical, religious, and/or political views. From the religious side, questions of purpose are ever‐present. We explore this interplay in five broad categories: chance, progress, intelligence, eugenics, and the evolution of religious practices, each the subject of a semester long symposium. The intellectual influence of evolutionary biology has had a broad societal impact in these areas. Based on our experience, we draw attention to a number of relevant facts that, while accepted by experts in their respective fields, may be unfamiliar outside them. We list common areas of miscommunication, including specific examples and discussing causes: sometimes semantics and sometimes more substantive knowledge barriers. We also make recommendations for those attempting similar dialogue.     

ECOLOGY AND PHYSIOLOGY OF HIBERNATION AND OVERWINTERING AMONG FRESHWATER FISHES, TURTLES, AND SNAKES

1. Freshwater fishes are the most northerly of freshwater ectotherms, followed by frogs. North American freshwater snakes, turtles, and salamanders do not range farther north than southernmost Canada. 2. Freezing and desiccation are the main challenges during terrestrial hibernation of ectotherms. Oxygen depletion, water balance, and ionic balance are the major problems for air breathing ectotherms that hibernate underwater. 3. The importance of accumulation of energy stores for overwintering among fishes depends upon the length and severity of the winters, whether or not there is springtime reproduction, body size, latitude, and the availability and use of food during overwintering. 4. Fishes can decrease energy demands during the winter by reductions in activity, metabolic depression, and entrance in semi-torpidity. 5. Adaptations for coping with hypoxia and anoxia among overwintering freshwater fishes may include metabolic depression, a decrease in blood O₂ affinity, microhabitat selection, air breathing, short-distance migration, biochemical modifications aimed at adjusting glycolytic rates, and alcoholic fermentation. 6. Freshwater turtles have a worldwide northern limit of approximately 50° N, which means that some species spend about half of their lives hibernating. 7. Aquatic turtles normally hibernate underwater, although occasionally they hibernate on land. In water they usually hibernate in a hypoxic or anoxic (mud) environment and in relatively shallow water. Wintertime movements of unknown frequency occur in some species. 8. The hatchlings of many turtle species can overwinter in the nest. Among northern species this behaviour is most common among painted turtles, whose hatchlings can withstand freezing. 9. Mortality among adult turtles is probably highest during the hibernation cycle. 10. Temperature appears to the most important cue for entry and exit from hibernation among freshwater turtles. 11. Little is known of the energetics of overwintering turtles. Energy stores for overwintering may be more important at lower latitudes than at higher ones, due to the higher metabolic rates of overwintering, but non-feeding, southern turtles. 12. The ability of turtles to tolerate submergence is a function of temperature, degree of water oxygenation, latitude of origin, efficacy of extrapulmonary respiratory pathways, and metabolic rate. 13. For turtles that hibernate in an anoxic hibernaculum, and for those without sufficient extrapulmonary uptake of O₂ to allow metabolism to be completely aerobic, the most important physiological perturbation is an acidosis developed from a continuing production of lactate. If sufficient O₂ can be obtained, the most likely factors limiting hibernation time are water balance and ion balance. 14. Mechanisms of turtles for coping with acidosis include metabolic depression, integumental CO₂ loss, bicarbonate buffering, and changes in ion concentrations that minimize the decrease in SID (strong ion difference). The most important among the latter are a decrease in plasma [Cl^-] and large increases in plasma calcium and magnesium. 15. Turtles are unique among reptiles in their ability to maintain both cardiovascular and nervous system function during prolonged anoxia. 16. Turtles gain weight from water uptake during submerged hibernation, but apparently maintain some kidney function; however, osmoregulation is one of the least known areas of the physiology of hibernation. 17. Recovery of turtles upon emergence commences with a rapid hyperventilatory compensation of pH, followed by a slower adjustment of ion levels. Basking speeds recovery greatly. 18. While hibernation of turtles in the northern parts of their ranges is most likely very stressful physiologically, northern range limits are more likely to be determined by reproductive restraints than by the rigors of extended hibernation. 19. The superior ability of turtles to tolerate anoxia may be more the result of an annual hibernation than of their diving habits during active periods of the year. 20. Freshwater snakes usually hibernate on land. However, they appear to be capable of aquatic hibernation and may not do so because of the risk of death from anoxia. 21. Some species of terrestrial snakes are known to hibernate underwater, and are able to do so in the laboratory for months. In the field, this behaviour is considered opportunistic, as there is no evidence to suggest that any snakes can tolerate extended anoxia.     

THE MORPHOLOGY AND RELATIONSHIPS OF RHODEA,TELANGIUM, TELANGIOPSIS,AND HETERANGIUM

This study deals with four form or organ genera from the Upper Mississippian (Chester Series) of the Illinois Basin, and provides evidence that they were produced by a single natural genus with gymnospermous affinity. The plant remains—compressions, impressions, petrifactions, and specimens that combine compression or impression with petrifaction—allow examination of both external morphology and internal anatomy. The specimens include foliage corresponding to Rhodea, stems and petioles corresponding to Heterangium, and synangiate fructifications corresponding to either Telangium or Telangiopsis. The stems and foliage are considered parts of the same plant because of the identity of the anatomical and cuticular features of petioles attached to stem and those petioles with attached foliage. The fertile material is regarded as part of the same plant because: (1) The anatomy of axes of the fertile specimens is like that of the sterile specimens. (2) A single specimen may contain both sterile Rhodea-type axes and fertile regions. (3) Axes bearing synangia have the same size and patterns of divisions as the sterile foliage. Features that indicate lyginopterid affinities include: (1) Equal forking of the petiole. (2) Presence of fiber bands in the outer cortex and sclerotic nests in the inner part of the cortex. (3) Crowded circular bordered pits on the lateral walls of the metaxylem tracheids. (4) The presence of a small amount of secondary xylem. A variety of structural details of the stem and petiole suggest the genus Heterangium. The phyletic position of the plant that produced Rhodea, Telangium, Telangiopsis, and Heterangium is reviewed in light of such discoveries as the presence of a planated frond that lacks a lamina and the presence of both monolete and trilete microspores in a single synangium.     

MASS FRAGMENTOGRAPHY OF PHENYLETHYLAMINE, m- AND p-TYRAMINE AND RELATED AMINES IN PLASMA, CEREBROSPINAL FLUID, URINE, AND BRAIN

—A mass fragmentographic method for the assay of phenylethylamine (PEA) and a number of related amines in several biological materials is described. The gas chromatographic column employed for this analysis is a 12ft 1/8 in. o.d. steel column packed with 0.5% OV₂₂+ 2% SE54 + 1% OV₂₁₀ coated on 80/100 mesh chromosorb W (HP). The mass spectral characteristics of these amines are illustrated, compared, and discussed. Of the various monoamines which could be measured, only PEA, m- and p-tyramine were detected in measurable quantities. Phenylethanolamine and p-octopamine were found in trace amounts in urine, plasma, cerebrosponal fluid, and rat brain. No diurnal variation in the urinary excretion of PEA, m- and p-tyramine was observed. Plasma concentration of PEA or p-tyramine did not significantly change 1 h after eating a breakfast. Furthermore, consuming 200 g of Cadbury milk chocolate containing about 1 mg of PEA, 0.1 mg of phenylethanolamine and 10 mg of p-tyramine did not significantly alter urine excretions of these three amines. In the brain, as has been reported by others, we found that PEA and p-tyramine are not evenly distributed and that the highest concentrations are found in the hypothalamus and caudate. From the results obtained we concluded that PEA, m- and p-tyramine are probably produced from endogenous sources and that the direct contribution of diet to their urine excretion is small.