bluuebunny/crossref_metadata_2025_split huggingface dataset:
Statistical analysis of the spatio‐temporal dynamics of rubber tree (Hevea brasiliensis) trunk phloem necrosis: no evidence of pathogen transmission
Authors: Peyrard N. , Pellegrin F. , Chadœuf J. , Nandris D. 
Published: September 2006

SummaryTrunk phloem necrosis (TPN) of Hevea brasiliensis is an irreversible syndrome of the phloem that spreads from the collar towards the tapping cut. It is responsible for the cessation of latex production, the main constraint in rubber plantations worldwide. Numerous investigations have been undertaken to understand the mechanisms of this disease. The apparent linear spread of TPN supported the initial hypothesis of a biotic causal agent for TPN. However, previous and recent aetiological analyses remained inconclusive and the pathogen hypothesis is tending to be abandoned. In this paper we present a complementary statistical analysis of spatio‐temporal epidemiological data collected in a rubber plantation in Côte d'Ivoire. There, four study plots were surveyed each year from 2000 to 2003, with tree‐by‐tree disease assessment. In two plots, the tapping knife was systematically disinfected with sodium hypochlorite to stop any virus or viroid transmission. Based on permutation tests, our analysis confirmed the aetiological results: there was no evidence for spread by pathogen transmission. However, the spatial structure of the disease was clear. These results strengthen the current alternative scenario of a multi‐factor physiological disease caused by an accumulation of exogenous and endogenous stresses. Spatial heterogeneity of the risk factors probably results in the presence of areas of stress that can explain the spatial patterns observed among the TPN cases. The final contribution of this study was confirmation of the curative effect of sodium hypochlorite in the earliest stages of the disease, thus opening the way for control of this disease.
Traumatic resin canals as markers of infection events in Douglas‐fir roots infected with Armillaria root disease
Authors: Cruickshank M. G. , Lejour D. , Morrison D. J. 
Published: September 2006

SummaryIn response to an infection, traumatic resin canals (TRCs) are formed in the roots of many conifers, which may be used to determine the timing and sequence of infection events essential for epidemiological studies of root diseases. Juvenile Douglas‐fir (Pseudotsuga menziesii) tree roots at coastal and interior sites in British Columbia were wounded at various times of the year or were inoculated with an isolate of Armillaria ostoyae, and root sections were taken to determine the timing and extent of TRC formation. Naturally infected Douglas‐fir were also examined to determine the extent of the TRCs in infected and uninfected roots on infected trees and in the lower stem. Wounds made in March and October had poor or no TRC formation while the summer wounds responded strongly and were associated with resin soaking. Roots wounded in October did not respond until the following year in all trees except one. Trees produced TRCs and resin soaked tracheids at all times in response to the fungal inoculations. The most striking difference between wounding or fungal inoculation was the multiple bands of TRCs produced in response to the fungus. TRCs at natural A. ostoyae infections were found 92% of time in roots at the stem junction and 74% of the time in the stem at soil line. TRCs were produced in uninfected roots on infected trees but disappeared with increasing distance from the initiating lesion. TRCs can be used to time yearly and seasonal root infections when they can be traced from an identified lesion.
Acquisition and Transmission of two Begomoviruses by the B and a non‐B Biotype of Bemisia tabaci from Zhejiang, China
Authors: Jiu M. , Zhou X.‐P. , Liu S.‐S. 
Published: September 2006

AbstractAcquisition and transmission was studied of Tomato yellow leaf curl China virus (TYLCCNV) and Tobacco curly shoot virus (TbCSV) by the B and a non‐B biotype (China‐ZHJ‐1) of Bemisia tabaci from Zhejiang, China. The frequency of TYLCCNV and TbCSV detection by PCR in whitefly adults increased with increasing length of feeding on virus‐infected plants. The virus DNA was detected by PCR in 40% of the B biotype adults tested after a period of 30 min access to infected plants and in all adults after a 12‐h period of access. All ZHJ‐1 adults acquired TYLCCNV and TbCSV after a 48‐h period of access to the virus‐infected plants. Viruliferous B and ZHJ‐1 adults retained TYLCCNV DNA for their entire life when placed on healthy cotton plants. Viruliferous ZHJ‐1 adults retained TbCSV DNA for their entire life when placed on healthy cotton plants but the B biotype adults did not. Transmission of TYLCCNV was achieved with one B or ZHJ‐1 adult per plant, and the probability of transmission reached 100% when the number of adults was increased to 10 per plant. The efficiency for TYLCCNV transmission to healthy plants by adults of both B and ZHJ‐1 was much higher than that for TbCSV.
Quantification of Fusarium culmorum in Wheat and Barley Tissues Using Real‐Time PCR in Comparison with DON Content
Authors: Leišová L. , Kučera L. , Chrpová J. , Sýkorová S. , Šíp V. , Ovesná J. 
Published: September 2006

AbstractA real‐time polymerase chain reaction (PCR) assay was developed for the specific detection of Fusarium culmorum in infected seeds. Primers and TaqMan minor groove binder probe were derived from the sequences of a F. culmorum specific PCR product. The specificity of the assay was confirmed by test in seven Fusarium species and 21 non‐Fusarium fungal species. With serial dilutions of purified genomic DNA from F. culmorum isolate B as the template, the detection limit of the assay was found to be 0.9 pg of fungal genomic DNA per reaction. A significant correlation ( = 0.982) and collinearity was found between DNA concentration and Ct (cycle threshold) values of real‐time PCR assay with serial diluted DNAs extracted from three seed samples with different deoxynivalenol (DON) content. Eight barley and nine wheat varieties infected by F. culmorum isolate B were evaluated in 1 (barley samples) and in 4 years (wheat samples). The results of real‐time PCR analysis and enzyme‐linked immunosorbent assay testing for DON content were compared and a significant correlation was found for barley samples (r2 = 0.935). Concerning wheat we found rather complicated relationship between Ct values and DON contents influenced by environmental conditions of field trials. The real‐time PCR assay was found to be highly specific and sensitive. It could be used in phytopathological studies and praxis.
Influence of Sugar Beet Seed Treatment withPseudomonas fluorescensand Low Fungicide Doses on Infection withPythiumand Plant Yield and Quality
Authors: Kristek S. , Kristek A. , Guberac V. , Glavaš Tokić R. , Pavlovic H. 
Published: September 2006

AbstractThe effect of sugar beet seed inoculation with the bacteriumPseudomonas fluorescensand treatment with the fungicides Thiram 42‐S and Dithane S‐60 with and without seed inoculation aiming to control the root decay agentsPythium ultimumandPythium debarianumwas studied during a 2‐year trial on two soil types (Mollic Gleysols and Eutric Cambisols). The influence of the treatments on parameters of sugar beet yield and quality such as root yield, sugar content, sugar in molasses, sugar yield as well as percentage of the infected and decayed plants as a consequence of parasitic oomycete infestation will be described.
Effect of lake sediments of different trophic states on alkaline phosphatase activity
Authors: Jin Xiang Can , Wang Sheng Rui , Zhao Hai Chao , Bu Qing Yun , Chu Jian Zhou , Cui Ze , Zhou Xiao Ning , Wu Feng Chang 
Published: September 2006

AbstractSamples of sediments, interstitial water and overlying water were collected monthly under temperature‐controlled conditions to determine the effects of sediment types on the alkaline phosphatase activity (APA) in lake systems. The relationship between the total alkaline phosphatase activity (TAPA) and soluble reactive phosphorus (SRP) concentration also was examined. The study results indicate the variations of TAPA in the overlying water, and the interstitial water in different layers from different sediments was similar over time. They were influenced not only by the phosphate concentrations, but also were correlated with submerged plant and phytoplankton biomass. The direct effects of the sediment types on the APA were not readily obvious. Although the higher APA in sediment was probably responsible for the enzymatic response to the characteristics of sediments, other factors (e.g. growth of submerged plants and phytoplankton) also should be considered. The peak of the maximum velocity of the enzyme reactions (Vmax) at deeper sediment layers suggests another stratum in which the enzymatically mediated phosphorus regeneration was active. This finding contributes to our understanding of phosphorus cycling in lake sediments.
Synthesis of a new conceptual model to facilitate management of ephemeral deflation basin lakes
Authors: Gawne Ben , Scholz Oliver 
Published: September 2006

AbstractEphemeral deflation basin lakes are widespread throughout arid and semiarid regions of the Murray–Darling Basin in Australia. Although they are diverse, productive habitats, the water resources development has generally caused significant declines in their ecological condition. Managers are currently trying to protect or restore these systems, however, without an adequate theoretical framework on which to base management decisions. This is because the existing conceptual models provide little insight into the effects of any component of the flow regime except flooding. This paper reviews the effects of flooding and drying on lakes, using the information and conclusions therein to propose a conceptual model that identifies five stages in the flooding and drying cycle. This conceptual model incorporates elements of the Flood Pulse Concept, Trophic Cascade models and the Geomorphic–Trophic model, as they apply to these highly variable water systems.
Nuclear division of the vegetative cells, conchosporangial cells and conchospores of Porphyra yezoensis (Bangiales, Rhodophyta)
Authors: Wang Juan , Dai Jixun , Zhang Yiting 
Published: September 2006

SUMMARYTo confirm the position and timing of meiosis in Porphyra yezoensis Ueda, the nuclear division of vegetative cells, conchosporangial cells and conchospores was observed. An improved staining method using modified carbol fuchsin was introduced to stain the chromosomes of Porphyra. Pit‐connections between conchosporangial cells also stained well with this method. Leptotene, zygotene, pachytene, diplotene, diakinesis, metaphase, anaphase and telophase were observed in the conchosporangial cells. During the germination of conchospores, no characteristics of meiosis I were found. No difference between the nuclear division of vegetative cells and that of conchospores was observed, and 2–3 days were needed for the first cell division both in vegetative cells and conchospores. Therefore, the cell division that occurs during conchospore germination is not meiosis I. Our results indicate that the prophase of meiosis I begins during the formation of conchosporangial branches, and metaphase I, anaphase I and telophase I take place during the maturation of conchosporangial branches. Then the three‐bivalent nucleate sporangia complete cell division to form two individual conchospores, each with one three‐univalent nucleus. The conchospores released from the sporangia are at meiotic interphase. Meiosis II occurs at the first nuclear division during conchospore germination, which is a possible explanation for the observation of mosaic thalli in mutant germlings of P. yezoensis. The mosaic thalli might also arise from gene conversion/post meiotic segregation events, comparable to those in Sordaria fimicola (Roberge ex Desm.) Ces. & De Not. and Neurospora crassa Shear & B.O. Dodge.
New records of three marine red algae from Japan
Authors: Masuda Michio , Tani Masaya , Kurihara Akira 
Published: September 2006

SUMMARYThree species in the red algal order Ceramiales, Dasya longifila Masuda et Uwai (Dasyaceae), Endosiphonia horrida (C. Agardh) P. Silva (Rhodomelaceae) and Laurencia flexilis Setchell (Rhodomelaceae), are reported from Japan for the first time, and their morphological features are described along with taxonomic comments. Our findings point to the northernmost limit of geographic distribution of these species in the north‐western Pacific. Dasya longifila is characterized by small, sparsely corticated axes, long pseudolaterals in which intercalary cell divisions take place, and a small number of tetrasporangial stichidia and spermatangial branches per fertile pseudolateral. Endosiphonia horrida is characterized by frequently anastomosing branches that form a bush‐like tuft without a percurrent axis, inner cortical cells becoming the same length as the axial and periaxial cells, and luxuriously developed, unbranched trichoblasts. Laurencia flexilis is characterized by numerous cartilaginous rigid axes developing from a basal disc without creeping branches, the production of 4 periaxial cells per vegetative segment and the absence of longitudinally oriented secondary pit‐connections between contiguous superficial cortical cells.
Hippocampal CA3 pyramidal cells selectively innervate aspiny interneurons
Authors: Wittner Lucia , Henze Darrell A. , Záborszky László , Buzsáki György 
Published: September 2006

AbstractThe specific connectivity among principal cells and interneurons determines the flow of activity in neuronal networks. To elucidate the connections between hippocampal principal cells and various classes of interneurons, CA3 pyramidal cells were intracellularly labelled with biocytin in anaesthetized rats and the three‐dimensional distribution of their axon collaterals was reconstructed. The sections were double‐stained for substance P receptor (SPR)‐ or metabotropic glutamate receptor 1α (mGluR‐1α)‐immunoreactivity to investigate interneuron targets of the CA3 pyramidal cells. SPR‐containing interneurons represent a large portion of the GABAergic population, including spiny and aspiny classes. Axon terminals of CA3 pyramidal cells contacted SPR‐positive interneuron dendrites in the hilus and in all hippocampal strata in both CA3 and CA1 regions (7.16% of all boutons). The majority of axons formed single contacts (87.5%), but multiple contacts (up to six) on single target neurons were also found. CA3 pyramidal cell axon collaterals innervated several types of morphologically different aspiny SPR‐positive interneurons. In contrast, spiny SPR‐interneurons or mGluR‐1α‐positive interneurons in the hilus, CA3 and CA1 regions were rarely contacted by the filled pyramidal cells. These findings indicate a strong target selection of CA3 pyramidal cells favouring the activation of aspiny classes of interneurons.
Lack of localization of 5‐HT6 receptors on cholinergic neurons: implication of multiple neurotransmitter systems in 5‐HT6 receptor‐mediated acetylcholine release
Authors: Marcos Beatriz , Gil‐Bea Francisco J. , Hirst Warren D. , García‐Alloza Mónica , Ramírez María J. 
Published: September 2006

AbstractThe involvement of the cholinergic system in learning and memory together with the cognitive enhancing properties of 5‐HT6 receptor antagonists led us to study the relationship between 5‐HT6 receptors and cholinergic neurotransmission. A selective cholinergic lesion, induced by injection of the immunotoxin 192‐IgG‐Saporin into the nucleus basalis magnocellularis, failed to alter the density of 5‐HT6 receptor mRNA or protein expression in the deafferentated frontal cortex, suggesting that 5‐HT6 receptors are not located on cholinergic neurons. The 5‐HT6 receptor antagonist SB‐357134 (0.001–1 µm) induced a concentration‐dependant K+‐evoked [3H]acetylcholine (ACh) release in vitro in rat cortical and striatal slices, which was blocked by tetrodotoxin. SB‐357134, up to 1 µm, stimulated glutamate release in cortical and striatal slices. In the cortex, riluzole (1 µm) blocked the SB‐357134‐induced K+‐stimulated [3H]ACh release, and simultaneous administration of MK‐801 (1 µm) and SB‐357134 (0.05 µm) elicited an increase in K+‐evoked ACh release. In the striatum, SB‐357134, 1 µm, decreased dopamine release, and the increase in K+‐evoked [3H]ACh release induced by 5‐HT6 receptor blockade was reversed by the D1 receptor antagonist, SCH23390 (1 µm). In both the frontal cortex and striatum, bicuculline, 1 µm, showed no effect on SB‐357134‐evoked [3H]ACh. These results are discussed in terms of neurochemical mechanisms involved in 5‐HT6 receptor functions.
Early‐phase of learning enhances communication between brain hemispheres
Authors: Cybulska‐Klosowicz Anita , Kossut Malgorzata 
Published: September 2006

AbstractIn the somatosensory system, inputs from one side of the body are only transmitted to the contralateral primary somatosensory cortex, but both sides of the body representation can interact via interhemispheric connections. These interactions depend on the behavioural requirements of the animal and its level of arousal. During the process of learning, alertness and attention may modify the responsiveness of neuronal pathways. We functionally mapped the brains of mice by using [14C]2‐deoxyglucose (2DG) autoradiography during the first and the third session of a classical conditioning paradigm, involving whiskers stimulation on one side of the muzzle paired with an aversive or appetitive unconditioned stimulus. During the first pairing session, an increased 2DG uptake was seen in the barrel cortex of both hemispheres, independently of the type of applied unconditioned stimulus. In the third session of the sensory pairing, activation of the barrel cortex was solely contralateral, as expected after unilateral whisker stimulation. Thus, sensory stimulation directed to one cerebral hemisphere during the initial stages of Pavlovian conditioning activates the primary sensory area in both hemispheres. These results suggest that during the early phase of conditioning, when alertness is presumably strongest, the interhemispheric interactions are enhanced.
Dopamine action in the substantia nigra pars reticulata: iontophoretic studies in awake, unrestrained rats
Authors: Windels François , Kiyatkin Eugene A. 
Published: September 2006

AbstractDopamine (DA) neurons located in the substantia nigra pars compacta release DA not only via axonal terminals, affecting neurotransmission within the striatum, but also via dendrites, some of which densely protrude into the substantia nigra pars reticulata (SNr). Although the interaction of dendritically released DA with somatodendritic autoreceptors regulates DA cell activity, released DA may also affect SNr neurons. These cells, however, lack postsynaptic DA receptors, making it unclear how locally released DA modulates their activity. Although previous work in brain slices suggests that DA might modulate the activity of GABA inputs, thus affecting SNr neurons indirectly, it remains unclear how increased or decreased DA release might affect these cells exposed to normal afferent inputs. To explore this issue, we examined the effects of iontophoretic DA and amphetamine on SNr neurons in awake, unrestrained rats. DA had no consistent effects on SNr cells but amphetamine, known to induce DA release, dose‐dependently inhibited most of them. This effect was blocked by SCH23390, a selective D1 receptor blocker, which itself strongly increased neuronal discharge rate. As GABA input is a major factor regulating the activity of SNr neurons, our data suggest that dendritically released DA, by interacting with D1 receptors on striato‐nigral and pallido‐nigral afferents, is able to decrease this input, thus releasing SNr neurons from tonic, GABA‐mediated inhibition. Surprisingly, a full DA receptor blockade (SCH23390 + eticlopride) did not result in the expected increase in SNr discharge rate, suggesting that other mechanisms are responsible for behavioral abnormalities following acute disruption of DA transmission.
Kv4 channels sensitive to BmTX3 in rat nervous system: autoradiographic analysis of their distribution during brain ontogenesis
Authors: Vacher Hélène , Diochot Sylvie , Bougis Pierre E. , Martin‐Eauclaire Marie‐France , Mourre Christiane 
Published: September 2006

AbstractThe binding site distribution of sBmTX3, a chemically synthesized toxin originally purified from the venom of the scorpionButhus martensi, was investigated in adult and developing rat brain, using patch‐clamp experiments and quantitative autoradiography. The molecular basis of these sBmTX3 sites was analysed by electrophysiology on transient Kv currents recorded in mammalian transfected cells. The rapidly activating and inactivating Kv4.1 current was inhibited by sBmTX3 (IC50, 105 nm). The inhibition was less effective on Kv4.2 and Kv4.3 channels and the toxin did not affect other transient currents such as Kv1.4 and Kv3.4. The distribution of the125I‐sBmTX3 binding sites was heterogeneous, with a 113‐fold difference between the highest and the lowest densities in adult rat brain. The site density was particularly important in the caudate–putamen and accumbens nucleus, thalamus, hippocampal formation and cerebellum. The affinity of sBmTX3 remained constant during brain ontogenesis. The level of sBmTX3 binding sites was very low in prenatal and postnatal stages to postnatal day (P)12 but drastically increased from P15 in the major part of the studied structures except in the CA3 hippocampal field where the density was very high from P6. Thus, the distribution of sBmTX3 binding sites in rat brain and its electrophysiological characteristics suggest that sBmTX3 specifically binds to the Kv4 subfamily of K channels.
Comparison of chitinolytic enzymes from an alkaline, hypersaline lake and an estuary
Authors: LeCleir Gary R. , Buchan Alison , Maurer John , Moran Mary Ann , Hollibaugh James T. 
Published: September 2006

SummaryWe examined the genetic and physiological characteristics of chitin degrading enzymes expressed by fosmids cloned from two strains of chitinolytic gammaproteobacteria isolated from alkaline, hypersaline Mono Lake, California; and from a metagenomic library derived from an estuarine bacterial community (Dean Creek, Sapelo Island, GA, USA). The Mono Lake chitinolytic enzymes presented unique adaptations in terms of halo‐ and alkalitolerance. The sequence from one of the Mono Lake isolates (strain 12A) was a conventional family 18 glycosyl hydrolase; however, the expressed protein had a novel secondary activity peak at pH 10. We obtained a novel family 20 glycosyl hydrolase sequence from Mono Lake strain AI21. The activity of the expressed protein had a pH optimum of 10, several pH units higher than any other enzyme currently assigned to this family, and the enzyme retained 80% of its activity at pH 11. The enzyme was also halotolerant, retaining activity in salt solutions of up to 225 g l−1. Sequence analysis indicated a molecular weight of ∼90 kDa for the protein, and that it contained two active sites. Culture supernatant contained two chitinolytic proteins, 45 and 31 kDa, suggesting possible post‐expression modification of the gene product. In contrast, the sequence found in the estuarine metagenomic library and the functional characteristics of the protein expressed from it were those of a conventional family 18 glycosyl hydrolase.