Acidification of a Small Watershed in Southern Norway and Some Characteristics of Acidic Aquatic Environments

Continuous monitoring of a small watershed in southern Norway shows that pH has decreased significantly by almost half a unit (from 5.9 to 5.4), conductivity increased from 23 to 29 μS/cm within the period from 1965–1975. Changes are also detected in sediment analyses where Daphnia and Chaoborus are only found deeper than 3–4 cm. Forest clear-cutting activities have probably accelerated the acidification processes of the already highly vulnerable freshwater localities. The acidic lakes show a solute content below 0.4 meq/1, and the bicarbonate buffer system may no longer work efficiently. Spring thaw and autumn rain episodes are accompanied by strong alternations in the chemical environment of the lakes; by considerable drop in pH and increasing conductivity and sulphate content. With increasing acidification the planktonic community changes from a fish predation governed system (brown trout and Eurasian perch as dominant species) to an invertebrate predation governed one with dominant predators Heterocope and pelagic corixids. Pelagic zooplankton are primarily composed of littoral species: Bosmina longispina, Diaphanosoma brachyurum, Eudiaptomus gracilis and Heterocope saliens. The littoral plant and invertebrate communities are described and discussed.     

Paliurus Fruits from the Oligocene of South China and Their Phytogeographic Implications

Paliurus favonii Unger is recognized and described based on fruits from the Oligocene Ningming flora of Guangxi, South China. Characteristics of the present specimens include circular winged fruits that are 10.0–11.5 mm in diameter with a central endocarp at 3.0 to 4.0 mm in diameter. The specimens fall into the morphological range of the fossil species P. favonii, which has been observed in other Cenozoic sites in the Northern Hemisphere. The present discovery represents the lowest latitude distribution of P. favonii in the world, and we are presenting the first P. favonii fossil described with detailed cuticular characteristics from China. Further, this finding demonstrates that the genus existed in the Oligocene Ningming region, South China, and provides new information for understanding the fossil history. The dispersal mode for winged fossils demonstrates that wind dispersal is well-represented in the Oligocene Ningming flora.     

Morphologic and Aerodynamic Considerations Regarding the Plumed Seeds of Tragopogon pratensis and Their Implications for Seed Dispersal

Tragopogon pratensis is a small herbaceous plant that uses wind as the dispersal vector for its seeds. The seeds are attached to parachutes that increase the aerodynamic drag force and increase the total distance travelled. Our hypothesis is that evolution has carefully tuned the air permeability of the seeds to operate in the most convenient fluid dynamic regime. To achieve final permeability, the primary and secondary fibres of the pappus have evolved with complex weaving; this maximises the drag force (i.e., the drag coefficient), and the pappus operates in an “optimal” state. We used computational fluid dynamics (CFD) simulations to compute the seed drag coefficient and compare it with data obtained from drop experiments. The permeability of the parachute was estimated from microscope images. Our simulations reveal three flow regimes in which the parachute can operate according to its permeability. These flow regimes impact the stability of the parachute and its drag coefficient. From the permeability measurements and drop experiments, we show how the seeds operate very close to the optimal case. The porosity of the textile appears to be an appropriate solution to achieve a lightweight structure that allows a low terminal velocity, a stable flight and a very efficient parachute for the velocity at which it operates.     

Pattern of the Cyanide-Potential in Developing Fruits : Implications for Plants Accumulating Cyanogenic Monoglucosides (Phaseolus lunatus) or Cyanogenic Diglucosides in Their Seeds (Linum usitatissimum, Prunus amygdalus)

The absolute cyanide content of developing fruits was determined in Costa Rican wild lima beans (Phaseolus lunatus), oil flax (Linum usitatissimum), and bitter almonds (Prunus amygdalus). The cyanide potential (HCN-p) of the lima bean and the almond fruit began to increase shortly after anthesis and then stopped before fruit maturity. In contrast, the flax inflorescence had a higher HCN-p in absolute terms than the mature flax fruit. At all times of its development the bean fruit contained the monoglucosides linamarin and lotaustralin. The almond and the flax fruits contained, at anthesis, the monoglucosides prunasin, and linamarin and lotaustralin, respectively, while, at maturity, only the corresponding diglucosides amygdalin, and linustatin and neolinustatin, respectively, were present.     

八种水果中的多酚含量及其抗氧化性

测定了苹果、石榴、橄榄、芒果、香蕉、菠萝、葡萄和龙眼的壳、肉及核中的多酚含量及其抗氧化性。以70%丙酮(v/v)为提取溶剂,室温下超声波辅助浸提样品后得到提取液。采用普鲁士兰(Prussian blue)法测定了提取液中多酚和单宁的含量,利用FRAP法测定其抗氧化性。结果表明:提取液中多酚和单宁的含量均与其抗氧化性成正相关关系;石榴、橄榄、芒果、葡萄和龙眼等水果的壳与核有望成为天然抗氧化剂的新来源。     

Sedimentary environment of Devonian pelagic limestones in the Southern Alps

Primary sedimentary structures combined with the geometry of Devonian and Lower Palaeozoic lithosomes in the Southern Alps (Austria and Italy) suggest many doubts about the published environmental and bathymetric interpretation of some Lower to Middle Devonian pelagic nodular limestones as 'deep-water' abyssal deposits. Every graded bed is not necessarily aturbidite; a single or some turbiditic beds are not necessarily deep-water or abyssal deposits; carbonate dissolution does not necessarily take place only below the carbonate compensation depth (CCD). Data show that graded allodapic beds, like those of the Lower to Middle Devonian of the Alps, may have been deposited as storm layers at a depth not exceeding some hundreds of metres. Accordingly the margins between Lower Devonian shallow-water platform and basins were characterized by low gradient and transitional sedimentary conditions. They became very steep only at the Devonian–Carboniferous transition because of synsedimentary block faulting.     

Exploratory Activity of Rats in Three Different Environments

Adult male hooded (Long‐Evans) rats (Rattus norvergicus) were used to compare the efficiency of three types of tests (plain open field – OF, open field with a refuge – OD, and complex environment with a refuge – EX), for the evaluation of exploratory behaviour. The results confirmed that OF is a highly aversive situation with the animals showing elevated emotional response (defecation and urination) when compared to situations containing a refuge (OD and EX). Presence of a plain arena (OF and OD) does not elicit high exploratory performance, as shown by the delayed and reduced exit from the refuge in OD when compared to EX. Thus locomotor activity in OF (covered distance, number of rearings) probably reflects more of an escape reaction than a genuine exploratory behaviour. Conversely the presence of a complex environment seems to elicit a high exploratory performance expressed as a quick exit from the refuge, an increased time in the environment (more than 75% of the observation time) and intense locomotor patterns (large covered distances, great number of rearings) but with little emotional display (reduced defecation and urination). The results thus show the importance of considering ethological factors in the choice or development of laboratory tests.     

Mutant gene frequencies in cats of Southern England

Summary Three areas in Southern England have been sampled for frequency of nine mutant genes among the domestic cat population. The significance of the derived estimates are discussed and a brief comparison is made with the earlier estimate obtained by Searle. The frequencies seem comparable in the two surveys except for genes O and d. The estimates of these from the present study are significantly higher than those found earlier. Tentatively, it is proposed that human preference for orange cats may be responsible for the increase in O. No obvious reason exists for the higher frequency of d.

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Zusammenfassung In drei Gebieten Südenglands wurden Beobachtungen über die Häufigkeit von 9 Genmutanten bei Hauskatzen angestellt. Die Signifikanz der aus den getroffenen Feststellungen abgeleiteten Voraussagen wird besprochen und kurz mit durch Searle vorgenommenen Schätzungen verglichen. Die Häufigkeiten scheinen in beiden Fällen vergleichbar mit Ausnahme der Gene O (orange) und d (dilute). Die Vorhersagen für diese Gene sind nach der gegenwärtigen Untersuchung signifikant höher als die früher gefundenen. Es könnte die Möglichkeit bestehen, daß für die Steigerung der Häufigkeit des Gens O die menschliche Vorliebe für orangefarbene Katzen verantwortlich ist. Für die größere Häufigkeit des Gens d liegt kein offensichtlicher Grund vor.

     

Forelimb Kinematics of Rats Using XROMM,with Implications for Small Eutherians and Their Fossil Relatives

The earliest eutherian mammals were small-bodied locomotor generalists with a forelimb morphology that strongly resembles that of extant rats. Understanding the kinematics of the humerus, radius, and ulna of extant rats can inform and constrain hypotheses concerning typical posture and mobility in early eutherian forelimbs. The locomotion of Rattus norvegicus has been extensively studied, but the three-dimensional kinematics of the bones themselves remains under-explored. Here, for the first time, we use markerless XROMM (Scientific Rotoscoping) to explore the three-dimensional long bone movements in Rattus norvegicus during a normal, symmetrical gait (walking). Our data show a basic kinematic profile that agrees with previous studies on rats and other small therians: rats maintain a crouched forelimb posture throughout the step cycle, and the ulna is confined to flexion/extension in a parasagittal plane. However, our three-dimensional data illuminate long-axis rotation (LAR) movements for both the humerus and the radius for the first time. Medial LAR of the humerus throughout stance maintains an adducted elbow with a caudally-facing olecranon process, which in turn maintains a cranially-directed manus orientation (pronation). The radius also shows significant LAR correlated with manus pronation and supination. Moreover, we report that elbow flexion and manus orientation are correlated in R. norvegicus: as the elbow angle becomes more acute, manus supination increases. Our data also suggest that manus pronation and orientation in R. norvegicus rely on a divided system of labor between the ulna and radius. Given that the radius follows the flexion and extension trajectory of the ulna, it must rotate at the elbow (on the capitulum) so that during the stance phase its distal end lies medial to ulna, ensuring that the manus remains pronated while the forelimb is supporting the body. We suggest that forelimb posture and kinematics in Juramaia, Eomaia, and other basal eutherians were grossly similar to those of rats, and that humerus and radius LAR may have always played a significant role in forelimb and manus posture in small eutherian mammals.     

种子的脱水行为及其分子机制

成熟脱水是种子发育的末端事件。根据种子的脱水行为,可以把种子分为正常性、顽拗性和中间性种子。许多过程或者机制授予或者提高种子的脱水耐性,不同的过程可能在不同的水合水平上对水分丧失起保护作用,这些过程的缺乏或者无效表达可能决定个别物种的种子的脱水敏感性程度。到目前为止,涉及种子脱水耐性的过程或者机制有：细胞内脱分化;代谢的‘关闭’;抗氧化系统的存在和有效运转;保护性分子(包括胚胎发育后期高丰度表达蛋白,蔗糖、寡糖或者半乳糖苷环多醇,亲水脂分子,油素)的存在;以及在重新水合过程中修复机制的存在和运转。     

Systematic Consideration of Microcharacters of Fruits and Seeds in the GenusVerbascum(Scrophulariaceae)

A morphological and anatomical study of fruits and seeds often species ofVerbascumfrom south-west Spain has been made.The seeds showed considerable uniformity in shape, size, seed-coatornamentation and internal structure. Two groups of speciesare distinguished on the basis of indumentum of the capsules.The first group has branched hairs which do not appear in thesecond. Only one species,V. virgatummay be included in bothgroups. Other characters such as corolla size or stamen number,support separation of both groups and reaffirm the intermediateposition ofV. virgatum. A key to distinguish the taxa is provided.Copyright1997 Annals of Botany Company Pericarp; seed-coat; SEM; anatomy     

Effects of Fluctuating Temperature on Germination and Emergence of Seeds in Different Moisture Environments

Seeds of calabrese and carrot were sown in soil at differentmoisture contents or were germinated in polyethylene glycolsolution of equivalent water potential. The seeds were alsosubjected to temperature environments which were either constant,altering at 12 h intervals, or changing smoothly and continuouslyin a daily cycle. The environments had similar mean temperatures,similar accumulated numbers of day-degrees, and the changing-temperatureenvironments had similar upper and lower temperature limits.In soil, at low and moderate moisture stress, seedlings of bothcrops emerged faster in the changing-temperature environmentsthan at constant temperature; at high moisture stress, emergenceoccurred only in the changing temperature environments. In osmoticsolutions, germination (radicle emergence) of calabrese seedswas faster in changing-temperature environments, but germinationof carrot seeds was unaffected by the temperature treatments.The results indicate that interaction between moisture stressand temperature environment is important and that results ofexperiments run at both constant moisture stress and constanttemperature together may not relate directly to the field situation.     

The Role of the Sedimentary Regime in Shaping the Distribution of Subtidal Sandbank Environments and the Associated Meiofaunal Nematode Communities: An Example from the Southern North Sea

We combined sediment and faunal data to explore the role of the sedimentary regime in shaping the distribution of subtidal sandbank environments and the associated meiofaunal nematode communities at Broken Bank and Swarte Bank, in the southern North Sea. A variety of sediment transport processes occur in the area, differing in the frequency and magnitude of sediment mobility, and the continuum between erosion, translation and sediment accumulation. The seabed contained a variety of bedforms, including longitudinal furrows, and small to very large sandwaves. The bed sediments were dominated by fine and medium sands, with admixtures of silt and gravel. Based on sedimentary bedforms and grain size analysis, a total of 11 sedimentary facies were delineated, of which 8 were analysed in detail for their relationships with the meiofauna. The sedimentary facies fell clearly into groups of facies, respectively representing high, high-moderate and moderate, and episodic sediment mobility. For those sedimentary facies where daily movement of sediments and bedforms occurred (‘high’ sediment mobility), the resulting spatially homogeneous environments were dominated by an impoverished nematode community comprising small deposit feeders and large predators. Resistance to sediment movement and the ability to exploit alternative food sources were prominent functional features of the successful colonisers. Those facies characterised by relatively infrequent sediment mobility (‘episodic’ and ‘high-moderate and moderate’ sediment mobility) comprised a heterogeneous suite of benthic habitats, containing taxonomically and functionally diverse assemblages of nematodes of various sizes, feeding types and reproductive potential. Faunal distribution patterns here indicated trade-offs between the resistance to sediment movement, environmental tolerance and competitive abilities. Our focus on diverse assemblages of organisms with high turnover times, inhabiting highly dynamic sedimentary environments, has revealed new animal-sediment relationships of relevance to pure and applied science.     

Cytohistochemical Analysis of Malus domestica Borkh. Seeds from Shedding and Nonshedding Fruits

A histological, cytochemical, and ultrastructural investigation of seeds of control (nonshedding) and shedding fruits of Malus domestica Borkh. showed differences in the pattern of nutrient distribution. The kind and amount of storage compounds in the two seeds also differed. Protein bodies and starch were abundant in the control seeds and nearly absent in the seeds of shedding fruit. In the latter, there was a great abundance of phenols that exhibited a specific distribution in different tissues of the chalazal region. A cuticle was present on the inner side of the inner integument of the seeds of both control and shedding fruits. This cuticle was interrupted in the chalaza and formed a pathway for nutrient translocation, what we termed the "window." Cell wall changes observed in the chalazal window were probably associated with the different distribution pattern of storage compounds and with the control of nutrient routing. The delayed and variable development of the embryos of seeds in shed fruits may be related to both the altered pattern of storage substances and their translocation to the embryo.     

果实中糖的运输、代谢与积累及其调控

叶片光合产物向果实运输的主要形态是蔗糖,但在木本蔷薇科果树中,光合产物的主要运输形态为山梨醇.糖从质外体空间跨膜运入共质体的过程由糖运输蛋白介导,而糖运输蛋白的基因表达伴随着果实糖的积累而增强.蔗糖代谢酶参与了细胞内外4个与糖运输有关的无效循环.己糖代谢抑制是果实糖快速积累的前提.在木本蔷薇科果实中,蔗糖代谢酶活力仍非常活跃,表明蔗糖可能与山梨醇在果实生长发育中都起重要的作用.糖作为信号分子,调节了承担糖运输与代谢的基因的表达.自然环境因子和栽培措施能有效调控糖运输、代谢与积累.反义抑制Ivr基因表达能提高番茄果实含糖量的实验结果表明遗传工程调控糖积累的潜力.阐明糖信号与其它信号互作对糖运输与代谢的调控机制是今后研究的重点.     

Epistemological Implications of Fieldwork and Their Consequences

Fieldwork is anthropology's primary data-gathering device, providing a boundary marker from related disciplines. Since data obtained through fieldwork form the bases of anthropological theory, it is crucial that their truth value be analyzed. The paper discusses reasons for both the relative lack of epistemological concern in anthropology until recent times and its current vogue. The empirical foundations of fieldwork are examined and a grid is presented for judging the philosophical position of fieldworkers. Application of the methods suggested is illustrated by a case study of missionary/anthropologist field interaction. Finally, an argument is outlined against both rationalism and phenomenology as being antiscientific. These last two positions are seen as the logical result of anthropology's neglect of epistemology. [epistemology, fieldwork, methodology, recurrent relationships, empiricism]     

平原湖区农业生态环境的变化及整治

生态效益是经济效益的基础,经济效益是生态效益的结果。在农业生产中,没有一个良好的生态环境,就不可能有一个全面高产丰收的局面。长期以来,由于农业上的单一经营,治理上的顾此失彼,资源上的掠夺性开发,使农田、水体、生活等生态系统平衡失调,各种矛盾突出。尤其是近些年,国家把平原湖区设为商品粮、油、棉、渔、猪、禽、蛋、林等众多的基地,从而探讨湖区的农业生态环境问题及整治对策,显得尤为重要。以著名“四湖”生态经济区所辖市之一的湖北省洪湖市为例,地处江汉平原南部,东南靠长江,北依东荆河,西濒洪湖(湖北省第一大淡水湖泊)与“四湖”水系相连,是典型的平原湖     

Seasonal succession of algae in a eutrophic stream in Southern England

The epipelic and epilithic algal communities in a small eutrophic stream situated in southern England expanded rapidly during March of both 1973 and 1974 primarily in response to changing light conditions. Although numbers varied greatly during the summer, these fluctuations were probably not due to nutrient, temperature or light conditions. High rates of disappearance of algae from the substrate were correlated with flooding, a deterioration of attachment characteristics and high metabolic rates. The episammic algal community consisted of only a few species, all of which showed maximum development during the summer. Although the well developed attachment mechanism and small size of the species undoubtedly aid in their ability to colonize sand grains, each species must be able to withstand frequent burial in the bottom deposits. Although temperature was probably an important factor controlling the number of epiphytes associated with Cladophora glomerata, light seemed to be of relatively less importance. Large numbers of isopods, amphipods and copepods occurred in the stream but their grazing seemed to have had little effect of the standing crop of the algae.     

Seasonal succession of planktonic and epiphytic algae in a canal in Southern England

The standing crop of phytoplankton in a canal in southern England remained low during 1973 and 1974, seldom exceeding 5 × 10⁴ cells/1. Since phosphorus, nitrogen and silicon occurred abundantly in the water, competition with higher plants for some other substance must have limited development. Although the standing crop of epiphytic algae associated withNasturtium officinale andGroenlandia densa seemed to be limited by the number of attachment sites, this factor was of little importance in the case of algae attached toCladophora glomerata. Achnanthes minutissima v.cryptocephala was always predominant in the epiphytic assemblages, representing 50–8o% by numbers of the flora. The limited pool of predominant epiphytic taxa may have restricted the communities' ability to adapt to fluctuations in environmental conditions. The grazing of isopods, amphipods and molluscs probably never limited algal densities.