Contrasting genetic diversity and differentiation of populations of two successional stages in a Neotropical pioneer tree (Eremanthus erythropappus, Asteraceae)

Eremanthus erythropappus, commonly known as "candeia", is an abundant pioneer tree species, forming dense populations known as "candeial", but it is also found in forests at middle stages of succession. Trees from forests are bigger and occur in lower density than in the "candeial". The objectives of the present study were to investigate if the decrease in population density during successional process is accompanied by 1) changes in within-population genetic diversity, and 2) differentiation of populations. Eight populations, four of early successional stage ("candeial") and four of middle successional stages (forest), were analyzed with RAPD markers. The genetic diversity found was high compared to other tree species analyzed with RAPD markers. AMOVA revealed that most of the genetic variations of E. erythropappus were found within populations (85.7%), suggesting that this species is predominantly outcrossing. The relatively low differentiation among the populations can be attributed to small distances among the populations analyzed (0.2 to 10.8 km). No indication that populations from middle successional habitats show lower genetic variation than populations from early successional stages was found. The percentage of polymorphic fragments (82.8 and 84.8%) and the Shannon indexes (0.442 and 0.455) were similar in "candeial" and forest, respectively. These results suggest that if an increase in selection intensity occurred during succession, it did not result in a decrease in genetic diversity or that the selection effect was balanced by other factors, such as gene flow. Higher significant differentiation among E. erythropappus populations from "candeial" in relation to that among populations from forest was also not detected.     

High-performance liquid chromatography analysis of naturally occurring D-amino acids in sake

We measured all of the D- and L-amino acids in 141 bottles of sakes using HPLC. We used two precolumn derivatization methods of amino acid enantiomer detection with o-phthalaldehyde and N-acetyl-L-cysteine, as well as (+)-1-(9-fluorenyl)ethyl chloroformate/1-aminoadamantane and one postcolumn derivatization method with o-phthalaldehyde and N-acetyl-L-cysteine. We found that the sakes contained the D-amino acids forms of Ala, Asn, Asp, Arg, Glu, Gln, His, Ile, Leu, Lys, Ser, Tyr, Val, Phe, and Pro. We were not able to detect D-Met, D-Thr D-Trp in any of the sakes analyzed. The most abundant D-Ala, D-Asp, and D-Glu ranged from 66.9 to 524.3 μM corresponding to relative 34.4, 12.0, and 14.6% D-enantiomer. The basic parameters that generally determine the taste of sake such as the sake meter value (SMV; "Nihonshudo"), acidity ("Sando"), amino acid value ("Aminosando"), alcohol content by volume, and rice species of raw material show no significant relationship to the D-amino acid content of sake. The brewing water ("Shikomimizu") and brewing process had effects on the D-amino acid content of the sakes: the D-amino acid contents of the sakes brewed with deep-sea water "Kaiyoushinosousui", "Kimoto yeast starter", "Yamahaimoto", and the long aging process "Choukijukusei" are high compared with those of other sakes analyzed. Additionally, the D-amino acid content of sakes that were brewed with the adenine auxotroph of sake yeast ("Sekishoku seishu kobo", Saccharomyces cerevisiae) without pasteurization ("Hiire") increased after storage at 25 °C for three months.     

Provision of residents of the city of Kiev with vitamins C and B1. Effectiveness of a complex vitamin-mineral preparation in preventing spring vitamin deficiencies

The investigation was conducted on provision with vitamins C and B1 of Kyiv inhabitants limited contingent at spring period and efficiency of complex vitamin-mineral preparations in normalisation of the vitamins level in blood of human-subjects. The deficit of vitamin C in 54% and vitamin B1 in 18.5% of the investigated people was revealed. Supradin gave the best results among rest preparations ("Centrum", "Vitrum", "Duovit", "Multi-Tabs") in the normalization of the level of vitamin C and biologically-active form of thiamine (thiamindiphosphate) in the blood of investigated people.     

INTRODUCTION

Foliage-feeding forest insects have served as model systems in the study of animal populations for more than 50 years. Early studies emphasized identification of "key" mortality agents or density-dependent sources of mortality. However, these efforts became burdened by rhetorical ambiguity, and population ecologists are increasingly focusing on characterizing population behavior and identifying the processes that generate that behavior. Two types of behavior seem to be common in forest insect populations: periodic oscillations ("population cycles") and spatial synchrony (synchronous fluctuations over large geographic areas). Several population processes (e.g., host–pathogen interactions) have been demonstrated to be capable of producing periodic oscillations, but the precise identity of these processes remains uncertain for most forest insects and presents a challenge to future research. As part of these efforts, a greater emphasis is needed on the use of statistical methods for detecting periodic behavior and for identifying other types of population behavior (e.g., equilibrium dynamics, limit cycles, transient dynamics). Spatial synchrony appears to be even more ubiquitous in forest insect populations. Dispersal and regional stochasticity ("Moran effect") have been shown to be capable of producing synchrony, but again more research is needed to determine the relative contribution of these processes to synchrony observed in natural populations. In addition, there is a need to search for other types of time–space patterns (e.g., traveling waves, spiral waves) in forest insect populations and to determine their causes. Received: April 25, 2000 / Accepted: September 22, 2000     

四个桂花品种挥发油成分研究(英文)

采用顶空固相微萃取结合气质联用技术首次同时对桂花四大栽培品系代表品种白洁、败育丹桂、佛顶珠和金桂的挥发油成分进行对比研究。从四个代表品种中共分离鉴定了72个化学成分,其中,21个是共有成分,但这四个品系中还存在着不同。结果发现,α-甲基--α[4-甲基-3-戊烯基]环氧丙醇存在于4个品种中,是白洁、败育丹桂和佛顶珠的主要成分之一,含量高达14~16%,但在金桂中仅有3.94%;芳樟醇存在于四个样品中,在佛顶珠中含量最高(9.83%);3-乙烯基-3-甲基-环己烷酮(7.89%)仅存在于佛顶珠中,邻苯二甲酸二异丁酯仅存在于金桂中,并且含量最高(23.99%)。     

Allozyme Variation in the Rare Gulf Coast Endemic Polygonella macrophylla Small (Polygonaceae)

Abstract Polygonella macrophylla Small is a rare, perennial, primarily gynodioecious plant species endemic to a narrow zone of coastal sand pine scrub habitat along the Gulf of Mexico from Carrabelle, Florida, to Gulf Shores, Alabama (U.S.A.). The species is comprised of a crimson-red flowered form ("rubra"), known from only two populations at the eastern distributional limit of the species, and a white/pink flowered form ("alba") represented by several populations throughout the remainder of the range of the species. An electrophoretic investigation revealed that commonly used measures of gene diversity are very close to expected values in "rubra" given the combination of ecological attributes displayed by the species; however, gene diversity in "alba" is much lower than expected. Population differentiation is high, with estimates of the coefficient of gene differentiation ( G _ST ) indicating that more than 30% of the diversity is among populations. Lack of gene flow among populations, estimated to be at most 0.6 migrating individuals per generation for the species, is a likely cause of greater population differentiation. High inbreeding, detected both within populations and within the species, is suggestive of high rates of self-fertilization in hermaphroditic plants and/or biparental inbreeding in small populations.     

Mechanism of the activating effect of detergents and chelating agents on the Na, K-ATPase activity of erythrocyte ghosts

The reasons for differences in the Na,K-ATPase activity in rat erythrocyte ghosts obtained by hypoosmotic hemolysis in 10 mM Tris-HCl buffer pH 7.6 in the absence ("Tris-ghosts") and presence ("EDTA-ghosts") were investigated. Structurally different detergents (Triton X-100, Tween-20 and sodium deoxycholate) taken at optimal concentrations increased the enzyme activity in a similar way, i. e., 4-fold in "Tris-ghost" and by 30% in "EDTA-ghosts", the absolute activity of Na,K-ATPase in both preparations being levelled out. In the absence of EDTA, only 50-60% of the maximal enzyme activity could be revealed. Thus, in non-nuclear erythrocyte ghosts the maximal Na,K-ATPase activity can be revealed only upon a combined use of a detergent and chelator. It is concluded that the activating effect of the detergents consisting in the increase of the membrane permeability is realized on the outer surface of the membrane, whereas that of EDTA is localized on its inner surface, which is probably due to the disintegration of the cytoskeleton as a result of attachment of membrane-bound Ca2+.     

A primary response with an initial negative wave

In the anterosuperior and posterosuperior portions of the ectosylvian gyrus of dogs small foci were found in which clicks evoked responses with parameters close to those of primary responses (PRs), but with an initial negative wave. An analysis of PRs with an initial wave of different polarity was carried out by studying the reproducibility of the response during an increase in the frequency of stimulation and during the action of various drugs. PRs with an initial negative ("negative" focus) and positive (auditory area AI) waves were found to be reproduced when the frequency of stimulation was 20–30 Hz, whereas the negative phase of the classical PR disappeared when the stimulation frequency reached 10–15 Hz. The polarity of the response in these foci was unchanged after injection of a lethal dose of nembutal, but the negative phase of the classical PR disappeared during moderately deep anesthesia. Strychnine, on the other hand, considerably increased the amplitude of the negative wave in the positive-negative complex, but the initial negative potential was only very slightly and temporarily increased, and it was lost in the subsequent strychnine spike. GABA inhibited both the PR with initial negative wave and also the negative phase of the classical PR. The results suggest that PRs with different polarities of their initial wave differ in origin. The results of experiments with GABA indicate that PRs with an initial negative wave arise through excitation of apical dendrites.A. A. Bogomolets' Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 2, No. 5, pp. 488–496, September–October, 1970.     

Comparison of the crystal structures and intersubunit interactions of human immunodeficiency and Rous sarcoma virus proteases

The crystal structures of the proteases (PRs) encoded by the Rous sarcoma virus (RSV) and the human immunodeficiency virus (HIV) have been compared. The crystallographic monomer of HIV PR superimposes on the two crystallographically independent subunits of the RSV PR dimer with root mean square deviations of 1.45 and 1.55 A for 86 and 88 common C alpha atoms, respectively. There is a conserved structural core consisting of seven beta-strands forming two perpendicular layers, a helix, and the amino- and carboxyl-terminal beta-strands. PRs from related retroviruses fold into similar structures with surface turns of variable length between the beta-strands. Both HIV and RSV PR dimers have significant subunit-subunit interactions in three regions: the "firemen's grip" at the active site; the salt bridges involving Arg8, Asp29, and Arg87 of HIV PR; and the termini of the two subunits, which form a four-stranded antiparallel beta-sheet. The specific interactions of the termini differ in the two PRs. The carboxyl termini, residues 96-99 of HIV PR and residues 119-124 of RSV PR, contribute approximately 50% of the intersubunit ionic and hydrogen bond interactions and approximately 45% of the buried surface area involved in dimer formation. This information may be useful in the design of site-directed mutations or inhibitors of dimer formation.     

Functional significance of cortical evoked potentials

Experimental results indicating a limited and indirect dependence of the amplitudes of the first two phases of the primary response (PR) of the cat auditory cortex on the information content of the stimulus are described. The PR amplitude is slightly reduced during the action of positive acoustic stimuli. This is due, primarily, to activation of the EEG in response to positive stimuli, for a similar decrease in amplitude of the cortical PR against the background of an activated EEG is also observed to fine differential stimuli. No PRs to acoustic stimulation are found in the sensomotor cortex either before or after motor-food conditioning; they are recorded only in the auditory projection zone. The amplitude of the PRs falls regularly during fast (25–30/min) and prolonged repetitive acoustic stimulation, and the rate of fall is greater when the interval between stimuli is shortened. The appearance of PRs of high amplitude in response to infrequent stimuli of whatever quality indicates that these responses are dependent on a component of the orienting reaction. It is concluded that the role of the first two phases of the PR as an indicator of fine analysis of information by the brain is limited.I. P. Pavlov Institute of Physiology, Academy of Sciences of the USSR, Leningrad. Translated from Neirofiziologiya, Vol. 2, No. 4, pp. 423–428, July–August, 1970.     

Reid's paradox revisited: the evolution of dispersal kernels during range expansion

Current approaches to modeling range advance assume that the distribution describing dispersal distances in the population (the "dispersal kernel") is a static entity. We argue here that dispersal kernels are in fact highly dynamic during periods of range advance because density effects and spatial assortment by dispersal ability ("spatial selection") drive the evolution of increased dispersal on the expanding front. Using a spatially explicit individual-based model, we demonstrate this effect under a wide variety of population growth rates and dispersal costs. We then test the possibility of an evolved shift in dispersal kernels by measuring dispersal rates in individual cane toads (Bufo marinus) from invasive populations in Australia (historically, toads advanced their range at 10 km/year, but now they achieve >55 km/year in the northern part of their range). Under a common-garden design, we found a steady increase in dispersal tendency with distance from the invasion origin. Dispersal kernels on the invading front were less kurtotic and less skewed than those from origin populations. Thus, toads have increased their rate of range expansion partly through increased dispersal on the expanding front. For accurate long-range forecasts of range advance, we need to take into account the potential for dispersal kernels to be evolutionarily dynamic.     

Dietary conservatism may facilitate the initial evolution of aposematism

It has generally been assumed that warningly coloured organisms pay a cost associated with their increased visibility, because naïve predators notice and eat them. This cost is offset by their enhanced protection from educated predators who associate the colour pattern with unprofitability. However, some studies have suggested that avoidance of novel prey by avian predators ("dietary conservatism") can actually place novel colour morphs at a selective advantage over familiar ones, even when they are highly conspicuous. To test this idea, we experimentally simulated the appearance of a single novel-coloured mutant in small populations (20 individuals) of palatable artificial prey. The colour morph frequencies in each "generation" were determined by the relative survival of the previous generation under predation by birds. We used wild-caught European robins Erithacus rubecula foraging on pastry "prey" of different colours. The aim was to test whether prey selection by predators prevented or facilitated the novel colour morph persisting in the prey population over successive generations. We found that the novel colour morph quickly increased to fixation in 14/40 prey "populations", and at least once each in 8 of the 10 birds tested. Novel mutants of the classic aposematic colours (red and yellow) reached fixation most frequently, but even the green and blue novel morphs both increased to fixation in 2/40 trials. Novel colours reached fixation significantly faster than could be accounted for by drift, indicating active avoidance by the birds. These results suggest that a novel colour morph arising in a prey population can persist and increase under the selective pressure imposed by predators, even to the local exclusion of the original morph, despite being fully palatable. The consequences of this finding are discussed in relation to receiver psychology, the evolution of aposematism and the existence of polymorphism in Müllerian mimics.     

The influence of sociality on the conservation biology of social insects

Social insects (ants, bees, wasps and termites) as a group are species rich and ecologically dominant. Many are outstanding "ecological engineers", or providers of "ecosystem services", or potential bioindicator species. Few social insects are currently formally classified as Threatened, but this is almost certainly due to a lack of information on population sizes and trends in scarce species. The main influence that sociality has on threats faced by social insects is in reducing effective population sizes, increasing population genetic subdivision and possibly reducing levels of genetic variation relative to solitary species. The main influence that sociality has on threats from social insects is via its role in the ecological success of invasive species, which frequently pose a major hazard to native biotas. In some cases, social features underpinning ecological success in the original range almost certainly contribute to the success of invasive social insects. However, recent studies show or strongly suggest that, in some of the most notoriously invasive populations of ants, bees and wasps, novel social traits have arisen that greatly enhance the rate of spread and ecological competitiveness of these populations. Sociality can therefore represent either a liability or an asset in its contribution to the persistence of social insect populations.     

Purification and interaction with estradiol-17beta.

The combination of polyacrylamide gel electrophoresis and Concanavalin-A-Sepharose affinity chromatography has permitted the isolation on a preparative scale, of four molecular forms of rat alpha1-fetoprotein: a "slow" and a "fast" fraction, each separable into Concanavalin-A-adorbed ("high carbohydrate", i.e. rich in accessible alphaD-Mannosyl and alphaD-Glucosyl residues) and a Concanavalin-A-non adsorbed ("low carbohydrate") fractions. These four iso-alpha-fetoproteins (iso-AFP) bind estradiol-17beta. However, they disclose differences in both their association constants and number of binding sites for this hormone. Very high affinity sites (10(9)) are mainly located on the "slow-low carbohydrate" form. Low affinity, high capacity sites are preferentially located on the "high carbohydrate" form. These results confirm the molecular and functional heterogeneity of rat AFP and suggest that the carbohydrate moiety of the protein may have a role in estrogen-AFP interactions.     

Temporal predictive codes for spoken words in auditory cortex

Humans can recognize spoken words with unmatched speed and accuracy. Hearing the initial portion of a word such as "formu…" is sufficient for the brain to identify "formula" from the thousands of other words that partially match. Two alternative computational accounts propose that partially matching words (1) inhibit each other until a single word is selected ("formula" inhibits "formal" by lexical competition) or (2) are used to predict upcoming speech sounds more accurately (segment prediction error is minimal after sequences like "formu…"). To distinguish these theories we taught participants novel words (e.g., "formubo") that sound like existing words ("formula") on two successive days. Computational simulations show that knowing "formubo" increases lexical competition when hearing "formu…", but reduces segment prediction error. Conversely, when the sounds in "formula" and "formubo" diverge, the reverse is observed. The time course of magnetoencephalographic brain responses in the superior temporal gyrus (STG) is uniquely consistent with a segment prediction account. We propose a predictive coding model of spoken word recognition in which STG neurons represent the difference between predicted and heard speech sounds. This prediction error signal explains the efficiency of human word recognition and simulates neural responses in auditory regions.     

Dissociable influences of auditory object vs. spatial attention on visual system oscillatory activity

Given that both auditory and visual systems have anatomically separate object identification ("what") and spatial ("where") pathways, it is of interest whether attention-driven cross-sensory modulations occur separately within these feature domains. Here, we investigated how auditory "what" vs. "where" attention tasks modulate activity in visual pathways using cortically constrained source estimates of magnetoencephalograpic (MEG) oscillatory activity. In the absence of visual stimuli or tasks, subjects were presented with a sequence of auditory-stimulus pairs and instructed to selectively attend to phonetic ("what") vs. spatial ("where") aspects of these sounds, or to listen passively. To investigate sustained modulatory effects, oscillatory power was estimated from time periods between sound-pair presentations. In comparison to attention to sound locations, phonetic auditory attention was associated with stronger alpha (7-13 Hz) power in several visual areas (primary visual cortex; lingual, fusiform, and inferior temporal gyri, lateral occipital cortex), as well as in higher-order visual/multisensory areas including lateral/medial parietal and retrosplenial cortices. Region-of-interest (ROI) analyses of dynamic changes, from which the sustained effects had been removed, suggested further power increases during Attend Phoneme vs. Location centered at the alpha range 400-600 ms after the onset of second sound of each stimulus pair. These results suggest distinct modulations of visual system oscillatory activity during auditory attention to sound object identity ("what") vs. sound location ("where"). The alpha modulations could be interpreted to reflect enhanced crossmodal inhibition of feature-specific visual pathways and adjacent audiovisual association areas during "what" vs. "where" auditory attention.     

Bi-enzyme L-arginine-selective amperometric biosensor based on ammonium-sensing polyaniline-modified electrode

A novel L-arginine-selective amperometric bi-enzyme biosensor based on recombinant human arginase I isolated from the gene-engineered strain of methylotrophic yeast Hansenula polymorpha and commercial urease is described. The biosensing layer was placed onto a polyaniline-Nafion composite platinum electrode and covered with a calcium alginate gel. The developed sensor revealed a good selectivity to L-arginine. The sensitivity of the biosensor was 110 ± 1.3 nA/(mM mm(2)) with the apparent Michaelis-Menten constant (K(M)(app)) derived from an L-arginine (L-Arg) calibration curve of 1.27 ± 0.29 mM. A linear concentration range was observed from 0.07 to 0.6mM, a limit of detection being 0.038 mM and a response time - 10s. The developed biosensor demonstrated good storage stability. A laboratory prototype of the proposed amperometric biosensor was applied to the samples of three commercial pharmaceuticals ("Tivortin", "Cytrarginine", "Aminoplazmal 10% E") for L-Arg testing. The obtained L-Arg-content values correlated well with those declared by producers.     

Effects of Immigration on the Dynamics of Simple Population Models

Many simple population models exhibit the period doubling route to chaos as a single parameter, commonly the growth rate, is increased. Here we examine the effect of an immigration process on such models and explain why in the case of one-dimensional ("single-humped") maps, immigration often tends to suppress chaos and stabilise equilibrium behaviour or cyclical oscillations of long period. The conditions for which an increase of immigration "simplifies" population dynamics are examined.