Survival of Ranunculus repens L. (creeping buttercup) in an amphibious habitat

The turlough form of Ranunculus repens is subjected to several months' complete inundation with hard groundwater. Experimental flooding to the level of the soil surface had no effect on turlough or ruderal populations relative to drained controls. Experimental submergence resulted in direct tissue death of the ruderal population but did not affect the turlough population relative to drained controls. There was no detectable difference in the proportion of aerenchyma in drained, flooded and submerged roots of plants from either population. The proportion of aerenchyma increased with root age in the ruderal population. Up to twice the proportion of aerenchyma occurred in the lower third of the root in the turlough population relative to the middle and upper thirds. Submergence in artificially hardened tap water increased the amount of tissue death in the ruderal population, whereas it appeared to enhance the growth of plants from the turlough population relative to that of plants submerged in tap water. Only the ruderal population demonstrated a depth accommodation response in submerged conditions. Root concentrations of ethanol-soluble carbohydrates were up to three times higher in a field- collected turlough population during winter and autumn months than those in a ruderal population. Low levels of ethanol-insoluble carbohydrates were present in the turlough population but were absent from the ruderal population. Starch concentrations fluctuated greatly in the turlough population and were generally higher than those in the ruderal population. These results, together with those from previous investigations, suggest that the turlough population survives prolonged submergence by maintaining low levels of submerged photosynthesis, which may circulate oxygen within the plant tissues, and by utilizing storage carbohydrates for maintenance respiration.     

Consequences of flower heliotropism for reproduction in an alpine buttercup (Ranunculus adoneus)

Summary The flowers of the alpine snow buttercup Ranunculus adoneus track the sun's movement from early morning until mid-afternoon. Individual blooms last up to a week: younger female stage flowers show greater solar tracking fidelity than older hermaphrodite or dehisced flowers. Flowers aligned parallel to the sun's rays reach mean internal temperatures several degrees Celsius above ambient air temperature. As a flower's angle of deviation from the sun increases beyond 45 degrees, internal flower temperature is significantly reduced. Fly pollinators are seen disproportionately often on flowers aligned with the sun; this is due, in part, to their greater residence time on tracking flowers. Fly visitation is important to fecundity. When flies were excluded from flowers, some selfed seeds were matured, but total seed production was much less than in either handoutcrossed or open-pollinated flowers. Flowers that were tethered at random angles to prevent solar tracking set fewer, smaller seeds than unmanipulated control flowers. Reductions in seed weight were statistically consistent at different times in the season, but tethering influenced seed number per flower most strongly in the early season. Effects of tethering on maternal reproduction could be due to either pollinator diserimination, post-pollination developmental processes, or both. In a second series of experiments using fluorescent dye particles as pollen analogs, tethered donor flowers dispersed dye to as many recipients as paired control flowers, suggesting that solar tracking fidelity may have little effect upon this component of male reproduction.     

Managed grazing is an effective strategy to restore habitat for the endangered autumn buttercup (Ranunculus aestivalis)

The only protected habitat of the endangered autumn buttercup is a small, overgrown, wet meadow that no longer supports the species. We used an experimentally driven reintroduction to examine the role of rodent herbivory in limiting the survival and establishment of autumn buttercup at the site. We evaluated the effectiveness of livestock grazing and cages to exclude rodents by comparing survival of caged and uncaged transplants under two pasture management treatments (grazed vs. ungrazed). We found that transplant survival was greatest for caged plants in grazed pasture with 50% of plants surviving to the end of the second growing season. Grazing increased the species richness in the plant community and decreased the amount of cover for small mammals. Accordingly, rodent density and vole herbivory in late summer were significantly lower on grazed pasture. Our results indicate that rodent herbivores represent a major threat to the survival and reestablishment of autumn buttercup and livestock grazing and protective caging are effective strategies to reduce rodent populations and vole herbivory.     

The mechanism of floral heliotropism in the snow buttercup, Ranunculus adoneus

We designed field experiments using solar-tracking Ranunculus adoneus flowers to determine where photoreception occurred, which organs responded, and how movement was achieved. Flower peduncles bend eastward in the morning and gradually unbend over the course of the day. Peduncles were found to bend significantly more frequently in the middle region near the floral bracts, 1–3 cm below the flower, than elsewhere on the peduncle. Because the peduncle tip continued to track the sun even after the flower itself was removed, our experiments concentrated on shielding (or conversely, exposing) various portions of peduncles from (or to) sunlight. Photoreception occurred primarily in the portion of the stem just beneath the floral receptacle. By following the position of landmarks applied to the stem, we found that 40% more growth occurred on the shaded side of bent peduncles, compared to the sunlit side. In contrast, top-shielded peduncles did not solar track well and grew only 25% more on the shaded side than on the sunlit side. This growth differential corresponded to differences in cell length on the two sides of bent peduncles, with significantly longer epidermal cells occurring on the shaded side than on the sunlit side.     

Evaluating the relationship of autumn buttercup (Ranunculus acriformis var. aestivalis) to some close congeners using random amplified polymorphic DNA

Autumn buttercup, an endangered endemic of wet, saline meadows in Garfield County, Utah, is treated differently in various taxonomic references now in use in the region. The taxon is currently listed as endangered by the United States Fish and Wildlife Service under the name Ranunculus acriformis var. aestivalis L. Benson. Others treat it as R. acris var. aestivalis (L. Benson) Welsh. In an attempt to resolve the taxonomical disagreements and to quantitatively describe the genetic uniqueness of this taxon, putative close relatives of the autumn buttercup, namely R. occidentalis (Nevada County, CA), R. acris (introduced from Europe and now growing wild in Rich and Cache counties, UT), R. acriformis var. montanensis (Lincoln County, WY), R. acriformis var. acriformis (Emery and Sanpete counties, UT), and R. acriformis var. aestivalis were collected and analyzed using random amplified polymorphic DNA (RAPD) genetic markers amplified from total cellular DNA extracts. Twenty-three decanucleotide primers of arbitrary sequence were used for DNA amplification; over 350 markers were generated. The genetic marker data were analyzed using similarity coefficients and parsimony. Based on the results of those analyses and on a review of ecological and morphological characteristics, we have elevated the autumn buttercup to species rank as Ranunculus aestivalis (Benson) Van Buren & Harper.     

青藏高原高寒矮嵩草草甸碳增汇潜力估测方法

以广布于青藏高原的高寒矮嵩草草甸为研究对象,研究了草甸碳储存的场所、碳库容量随草甸演替的变化过程及其碳增汇潜力的空间分布格局,同时探讨了高寒草甸碳增汇潜力估测的困惑与解决方法。结果表明,高寒草甸生态系统碳增汇潜力空间分布格局差异极大,主要受到土层厚度和草地演化进程的影响。高寒草甸碳主要贮存于草毡表层,其增汇潜力在于退化草地草毡表层的恢复与重建。保持适宜厚度的草毡表层是协调高寒草甸生产与碳生态服务功能的关键。随着退化高寒草甸的恢复,土壤容重呈现下降趋势,计算其系统碳增汇潜力,需要用根土体积比进行土层深度的校正。高寒草甸具有较大的固碳潜力,但其潜力的发挥受到气候和草地恢复与管理措施的影响,比较漫长。     

The endangered Tunbridge buttercup (Ranunculus prasinus): Ecology,conservation status and introduction to the Township Lagoon Nature Reserve,Tasmania

Abstract Ranunculus prasinus is a mat-forming species of the marginal herbfields and tussock grasslands of brackish wetlands. It is only known from four wetlands, all on private land, in the driest part of Tasmania. The species has been successfully introduced from divisions from three of the populations into a secure reserve with similar vegetation to that of the natural populations. This is considered to be desirable and morally sound in that it increases the chances of survival of native biological diversity as a whole. However, ex situ measures and a gaining of security for natural populations would also be prudent.     

Morphological Variation in Populations of Ranunculus repens from the Temporary Limestone Lakes (Turloughs) in the West of Ireland

An unusual form of Ranunculus repens L. occurs in turlough basins(temporary lakes) in the West of Ireland. It is characterizedby more highly-dissected and glabrous leaves than the more typicalbroad-leaved form. Leaf dissection of both forms was quantifiedusing seed-derived plants which were cultivated in standardconditions. Leaves of both forms showed heteroblastic developmentand became increasingly dissected with each successively producedleaf until the adult leaf shape was attained around leaf 8.The dissection index of adult leaves was genetically based andhad a high heritability. Changes in leaf dissection were recordedacross a relatively deep, undulating turlough basin. The mostdissected leaf form was found deep within the basin among ahighly specialized species-poor community which was subjectedto the most prolonged period of inundation. An intermediate-leavedform occurred higher up the sides of the basin in a damp grasslandcommunity, where the period of inundation was more transient.A broad-leaved form occurred around the upper fringes of thebasin among a dry pastureland community. The intermediate-leavedform may have resulted from gene flow between the broad- anddissected-leaved populations, or may have evolved a distinctleaf shape adapted to the prevailing conditions at that pointwithin the basin. Copyright 2001 Annals of Botany Company Ranunculus repens L., turloughs, leaf shape, heritability, ontogeny, population biology     

利用Inverse PCR快速筛选单个T—DNA拷贝转基因水稻植株的方法

In order to obtain single T-DNA copy transgenic rice, we have established a quick method to estimate the T-DNA copy number in transgenic rice using inverse PCR (IPCR). IPCR was used to amplify junction fragments, i.e. plant genomic DNA sequences flanking the known T-DNA sequences, which will help to estimate the T-DNA copy number in transgenic rice. We have analyzed 20 transgenic plants of 15 transgenic lines. Most plants (12) contain one integrated T-DNA copy per genome, 3 plants contain two and 1 plant contains 3 copies. In 4 transgenic plants no T-DNA copies could be detected using this method. The IPCR results were further tested by Southern analysis and sequence analysis.     

Aspects of the Comparative Physiology of Ranunculus bulbosus L. and Ranunculus repens L.: I. Response to Nitrogen

Ranunculus bulbosus and R. repens are closely related taxonomicallyand coexist in the same general habitat but differ in that R.bulbosus only exceptionally shows vegetative multiplicationcontrasting with R. repens which reproduces extensively by meansof long branched stolons which root and form new daughter plantsat the nodes. The response of these two species to nitrogen was similar inthat an increase from 10 to 50 ppm nitrogen gave rise to greatlyincreased total dry weight and higher shoot to root ratios,whereas further nitrogen increase from 50 to 200 ppm had littleeffect. However, they differed in that at low nitrogen levelsthe perennating organ (corm) took priority in R. bulbosus withsexual reproduction assuming greater importance at the highernitrogen levels, whereas in R. repens the main storage organ(the stock) was not especially favoured at low nitrogen levelsreflecting perhaps the differences between this structure andthe corm in R. bulbosus. In R. repens the greatest responseto nitrogen was shown by the stolons although this was due toincreased branching and a higher dry weight per unit lengthat the higher levels of nitrogen (50 and 200 ppm). Primary stolonlength was not greatly affected by nitrogen level. Dry weightsof flowers and fruits in R. repens were very much lower thanin R. bulbosus. It is suggested that in R. bulbosus the emphasis lies firstin replacement of the parent at approximately the same siteby a daughter from the new corm and secondly in sexual reproductivespread. In R. repens lateral spread by vegetative propagationtakes precedence over all else and under low nitrogen conditionsbranching is sacrificed and energy is diverted to maintaininglong primary stolons. These, in turn, have the potential forproducing daughter plants at some distance from the parent andthis may be of considerable importance in field situations sincethe daughter may come to occupy more favourable sites than theparent.     

Sunny-side up: flower heliotropism as a source of parental environmental effects on pollen quality and performance in the snow buttercup, Ranunculus adoneus (Ranunculaceae)

Floral traits affect mating success via their influence on the microenvironment in which sexual reproduction occurs as well as their impact on pollinator attraction. Here we investigate the importance of flower heliotropism as a source of parental environmental effects on pollen quality and performance. Flowers of the snow buttercup, Ranunculus adoneus, closely track the sun's rays. We experimentally restrained flowers to test for effects of heliotropism on pollen quality and performance after pollination. When equivalent amounts of pollen were transferred to recipient pistils, pollen from solar-tracking donor flowers exhibited a 32% advantage in germination compared to pollen from stationary (tethered) donor flowers. By the end of anthesis, pistils of tracking flowers contained 40% more germinating pollen grains and 44% more pollen tubes midway down the style than pistils of stationary ones. Solar tracking had no direct effect on pollen tube growth. The greater amount of germinating pollen in tracking flowers accounted for the treatment effect on pollen tube density. A survey of pollen receipt and pollen germination in naturally tracking flowers indicated that solar tracking primarily affects pollen tube density by promoting pollen germination rather than pollen deposition. We conclude that flower heliotropism, by enhancing the paternal environment for pollen development and the maternal environment for pollen germination, represents a source of positive parental environmental effects on pollen performance in snow buttercups.     

Using otolith weight to estimate the age of haddock (Melanogrammus aeglefinus): a tree model application

In this study, we investigated whether otolith weight can be used to estimate fish age with the same level of accuracy as that of the traditional annuli counting technique in a commercially important species such as haddock (Melanogrammus aeglefinus). Results indicate that this method is highly effective for young fish (around 97% correct classification), whereas its powers of prediction decrease with the increasing age of the fish. For older fish, the otolith weight cannot be an accurate estimator of fish age if the weight overlap between the different age classes is too large. Nevertheless, the otolith weight technique is strictly dependent on correct age determination through the counting of annuli of those individuals used in the calibration. Hence, an increase in the accuracy of ageing obviously determines an increase of the power of otolith weight to estimate fish age. Therefore, we suggest that otolith weight could represent a routine technique for determination of the age structure of haddock populations. This technique has the merit to be objective, fast, 100% repeatable and has the same level of accuracy as that of annuli counting.     

Latrine survey as a method to estimate the population size of Arabian gazelles (Gazella arabica)

Arabian gazelle (Gazella arabica) populations have been decimated in most parts of their original range. As a cryptic, crepuscular species, Arabian gazelles are difficult to observe, rendering monitoring programs for conservation purposes a challenging endeavour. Latrine mapping has been suggested as an effective, time- and cost-efficient tool to survey and estimate the abundance of gazelles in remote areas with low population densities. In the present study we collected data from five populations in Saudi Arabia to address the question of how population estimates can be inferred from such latrine counts and uncovered a non-linear relationship between both variables. Methodologies applied during the five surveys differed between study sites, so caution is required when interpreting our data. Still, given the immediate threat to the survival of the species, there is an urgent need to establish a time- and cost-efficient sampling method that will be vital for the conservation of remnant pockets of natural populations and for the proclamation of new protected areas in Saudi Arabia and other countries in the Middle East, and the present data are the only available source of information in this context.     

A method to estimate body mass and relative age of exotic lagomorphs in the southern Neotropics

Exotic prey species can dramatically alter trophic interactions by functionally replacing native prey species. This pattern has been observed in the southern Neotropics, where introduced haresLepus europaeus Pallas, 1778 and rabbitsOryctolagus cuniculus (Linnaeus, 1758) have become the staple prey for native predators. Despite their importance as prey, no data are available on the mass and relative age of the lagomorphs on which native predators feed. We used linear regression models to predict the mass of lagomorphs from their hind-foot length, and investigated the influence of sex, season, and collection site on this relationship. Hind-foot length was a good predictor of body mass for both species and accounted for 58.4 and 71.6% of the variability in body mass for hares and rabbits, respectively. Sex and season significantly influenced the relationship, whereas the effect of collection site was negligible. Hind-foot length was also a good predictor of age class for hares and rabbits, allowing the discrimination between nonreproductive and reproductive classes for both species. Future research can use this method to determine the biomass and age class of exotic lagomorphs consumed by predators.     

Variation in leaves and petals of Ranunculus subgenus Batrachium on the Aegean Islands, analysed by multivariate analysis

Variation in leaves and petals was studied using canonical variate and cluster analyseS. In total of 33 populations from eight islands leaf variation in laminar, floating leaves was studied in Ranunculus peltatus subsp. peltatus, subsp. baudotii and subsp. saniculifolius, and in R. Tripartitus, all of which are heterophyllous in the Aegean area. The petal data set also included the homophyllous R. Trichophyllus. The results of the analyses show that the populations are morphologically well differentiated and that petal shape has a tendency to discriminate between the populations somewhat better than leaf shape does. There was no basis for subdividing the populations into taxa on these characterS. Analyses showed that up to 70% of the variation was distributed between populations, the remainder (5–18%) being within populations.     

Cementum annulus counts provide a means for age determination in Macaca mulatta (primates, anthropoidea)

14 teeth of 8 rhesus macaques (Macaca mulatta) of known age were analyzed to assess the usefulness of cementum annuli counts as a means of estimating chronological age. Methods used were histological examination of stained thin sections by light microscopy, and examination of polished and etched epoxy-embedded sections by scanning electron microscopy. In 11 of 14 cases, the known chronological ages of the individuals fell within the predicted age ranges based on cementum annuli counts; in 2 other cases, it fell within half a year of the ranges. Cementum annulus counts can provide valuable information about the age of primates living in semitropical environments. This is the most accurate method for aging skeletally adult primates that has yet been tested on animals of known age.     

Investigating deleterious effects of ultraviolet (UV) radiations on wheat by a quick method

Increasing air pollution has resulted in ozone depletion, which has led to an increase in the amount of ultraviolet (UV) radiation reaching the surface of earth posing hazardous effects on the plant yield. The chlorophyll a fluorescence transients were recorded in vivo using plant efficiency analyzer and analyzed according to JIP test, which can monitor photosystem II (PSII) behavior. This study aims to evaluate the sensitivity of different components of PSII to UV radiations and the extent of damage caused when wheat plants were exposed to UV radiations for 2 and 4 h. It was observed that functional disconnection of light harvesting complexes from PSII complex, accumulation of inactive reaction center, inactivation of oxygen evolving complex, and thus the linear electron transport process (ET₀/CS), were drastically affected by UV radiations. This study will contribute to understanding of the basic photosynthetic mechanisms affected in crop plants due to increased UV radiations. The knowledge obtained will be relevant for environmental and plant scientists to plan strategies to cope with stresses.     

The hockey-stick method to estimate evening dim light melatonin onset (DLMO) in humans

The onset of melatonin secretion in the evening is the most reliable and most widely used index of circadian timing in humans. Saliva (or plasma) is usually sampled every 0.5–1 hours under dim-light conditions in the evening 5–6 hours before usual bedtime to assess the dim-light melatonin onset (DLMO). For many years, attempts have been made to find a reliable objective determination of melatonin onset time either by fixed or dynamic threshold approaches. The here-developed hockey-stick algorithm, used as an interactive computer-based approach, fits the evening melatonin profile by a piecewise linear-parabolic function represented as a straight line switching to the branch of a parabola. The switch point is considered to reliably estimate melatonin rise time. We applied the hockey-stick method to 109 half-hourly melatonin profiles to assess the DLMOs and compared these estimates to visual ratings from three experts in the field. The DLMOs of 103 profiles were considered to be clearly quantifiable. The hockey-stick DLMO estimates were on average 4 minutes earlier than the experts' estimates, with a range of ?27 to +13 minutes; in 47% of the cases the difference fell within ±5 minutes, in 98% within ?20 to +13 minutes. The raters' and hockey-stick estimates showed poor accordance with DLMOs defined by threshold methods. Thus, the hockey-stick algorithm is a reliable objective method to estimate melatonin rise time, which does not depend on a threshold value and is free from errors arising from differences in subjective circadian phase estimates. The method is available as a computerized program that can be easily used in research settings and clinical practice either for salivary or plasma melatonin values.     

秦岭毛茛属植物(毛茛科)的分类学研究

记载了产于秦岭的毛茛属植物共11种,4变种,其中含秦岭分布新记录4种、3变种,它们是:美丽毛茛、丽江毛茛(变种)、毛果毛茛(变种)、丝叶毛茛(变种)、褐鞘毛茛、愚毛茛、匍枝毛茛;另外,收录了《秦岭植物志》遗漏的另外2种,即太白山毛茛和细长喙毛茛。经研究认为,《秦岭植物志》原记载的小毛茛Ranunculus ternatusThunb.在秦岭无分布。给出了秦岭毛茛属植物分种(变种)检索表;对每一种及种下等级的产地及分布进行了详细的论述。