bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chemosensory behavioural response of freshwater phytoplanktonic flagellates
Authors: CLEGG M. R. , MABERLY S. C. , JONES R. I. 
Published: December 2004

ABSTRACTUnlike behavioural responses to physical gradients, active responses to chemical gradients, and their physiological and ecological implications, have rarely been studied in freshwater phytoplanktonic flagellates. This study used microscale preference chambers to investigate the population and individual cell responses of five species exposed to four chemical gradients which commonly develop with depth in lakes: phosphate, oxygen, carbon dioxide and pH. Upon exposure of nutrient‐replete and ‐depleted cells to a phosphate gradient, only nutrient‐depleted cells of the autotrophic Chlamydomonas moewusii responded, accumulating at high concentrations. In contrast, all species responded to an oxygen gradient with Ceratium furcoides, Chlamydomonas moewusii, Dinobryon sertularia and Plagioselmis nannoplanctica preferring high concentrations whereas Euglena gracilis preferred low concentrations. In addition, all species displayed a strong affinity for carbon dioxide which was not mediated by detecting pH. Analysis of the swimming trajectories of individual cells showed that directed chemotaxes, rather than speed‐dependent chemokineses, were responsible for the observed preferences. These complex and diverse species‐dependent chemosensory responses may optimize photosynthesis, facilitate nutrient retrieval during migration, increase growth rate and may influence spatial and temporal distribution, contributing to the delineation of niche separation in phytoplanktonic flagellates.
Scaling phloem transport: information transmission
Authors: THOMPSON M. V. , HOLBROOK N. M. 
Published: December 2004

ABSTRACTSieve tubes are primarily responsible for the movement of solutes over long distances, but they also conduct information about the osmotic state of the system. Using a previously developed dimensionless model of phloem transport, the mechanism behind the sieve tube's capacity to rapidly transmit pressure/concentration waves in response to local changes in either membrane solute exchange or the magnitude and axial gradient of apoplastic water potential is demonstrated. These wave fronts can move several orders of magnitude faster than the solution itself when the sieve tube's axial pressure drop is relatively small. Unlike the axial concentration drop, the axial pressure drop at steady state is independent of the apoplastic water potential gradient. As such, the regulation of whole‐sieve tube turgor could play a vital role in controlling membrane solute exchange throughout the translocation pathway, making turgor a reliable source of information for communicating change in system state.
Impact of rising CO2 on emissions of volatile organic compounds: isoprene emission from Phragmites australis growing at elevated CO2 in a natural carbon dioxide spring†
Authors: SCHOLEFIELD P. A. , DOICK K. J. , HERBERT B. M. J. , HEWITT C. N. S , SCHNITZLER J.‐P. , PINELLI P. , LORETO F. 
Published: December 2004

ABSTRACTIsoprene basal emission (the emission of isoprene from leaves exposed to a light intensity of 1000 µmol m−2 s−1 and maintained at a temperature of 30 °C) was measured in Phragmites australis plants growing under elevated CO2 in the Bossoleto CO2 spring at Rapolano Terme, Italy, and under ambient CO2 at a nearby control site. Gas exchange and biochemical measurements were concurrently taken. Isoprene emission was lower in the plants growing at elevated CO2 than in those growing at ambient CO2. Isoprene emission and isoprene synthase activity (IsoS) were very low in plants growing at the bottom of the spring under very rich CO2 and increased at increasing distance from the spring (and decreasing CO2 concentration). Distance from the spring did not significantly affect photosynthesis making it therefore unlikely that there is carbon limitation to isoprene formation. The isoprene emission rate was very quickly reduced after rapid switches from elevated to ambient CO2 in the gas‐exchange cuvette, whereas it increased when switching from ambient to elevated CO2. The rapidity of the response may be consistent with post‐translational modifications of enzymes in the biosynthetic pathway of isoprene formation. Reduction of IsoS activity is interpreted as a long‐term response. Basal emission of isoprene was not constant over the day but showed a diurnal course opposite to photosynthesis, with a peak during the hottest hours of the day, independent of stomatal conductance and probably dependent on external air temperature or temporary reduction of CO2 concentration. The present experiments show that basal emission rate of isoprene is likely to be reduced under future elevated CO2 levels and allow improvement in the modelling of future isoprene emission rates.
Profiles of isoprene emission and photosynthetic parameters in hybrid poplars exposed to free‐air CO2 enrichment†
Authors: CENTRITTO M. , NASCETTI P. , PETRILLI L. , RASCHI A. , LORETO F. 
Published: December 2004

ABSTRACTPoplar (Populus × euroamericana) saplings were grown in the field to study the changes of photosynthesis and isoprene emission with leaf ontogeny in response to free air carbon dioxide enrichment (FACE) and soil nutrient availability. Plants growing in elevated [CO2] produced more leaves than those in ambient [CO2]. The rate of leaf expansion was measured by comparing leaves along the plant profile. Leaf expansion and nitrogen concentration per unit of leaf area was similar between nutrient treatment, and this led to similar source–sink functional balance. Consequently, soil nutrient availability did not cause downward acclimation of photosynthetic capacity in elevated [CO2] and did not affect isoprene synthesis. Photosynthesis assessed in growth [CO2] was higher in plants growing in elevated than in ambient [CO2]. After normalizing for the different number of leaves over the profile, maximal photosynthesis was reached and started to decline earlier in elevated than in ambient [CO2]. This may indicate a [CO2]‐driven acceleration of leaf maturity and senescence. Isoprene emission was adversely affected by elevated [CO2]. When measured on the different leaves of the profile, isoprene peak emission was higher and was reached earlier in ambient than in elevated [CO2]. However, a larger number of leaves was emitting isoprene in plant growing in elevated [CO2]. When integrating over the plant profile, emissions in the two [CO2] levels were not different. Normalization as for photosynthesis showed that profiles of isoprene emission were remarkably similar in the two [CO2] levels, with peak emissions at the centre of the profile. Only the rate of increase of the emission of young leaves may have been faster in elevated than in ambient [CO2]. Our results indicate that elevated [CO2] may overall have a limited effect on isoprene emission from young seedlings and that plants generally regulate the emission to reach the maximum at the centre of the leaf profile, irrespective of the total leaf number. In comparison with leaf expansion and photosynthesis, isoprene showed marked and repeatable differences among leaves of the profile and may therefore be a useful trait to accurately monitor changes of leaf ontogeny as a consequence of elevated [CO2].
Leaf photosynthesis and carbohydrate dynamics of soybeans grown throughout their life‐cycle under Free‐Air Carbon dioxide Enrichment
Authors: ROGERS A. , ALLEN D. J. , DAVEY P. A. , MORGAN P. B. , AINSWORTH E. A. , BERNACCHI C. J. , CORNIC G. , DERMODY O. , DOHLEMAN F. G. , HEATON E. A. , MAHONEY J. , ZHU X.‐G. , DELUCIA E. H. , ORT D. R. , LONG S. P. 
Published: December 2004

AbstractA lower than theoretically expected increase in leaf photosynthesis with long‐term elevation of carbon dioxide concentration ([CO2]) is often attributed to limitations in the capacity of the plant to utilize the additional photosynthate, possibly resulting from restrictions in rooting volume, nitrogen supply or genetic constraints. Field‐grown, nitrogen‐fixing soybean with indeterminate flowering might therefore be expected to escape these limitations. Soybean was grown from emergence to grain maturity in ambient air (372 µmol mol−1[CO2]) and in air enriched with CO2 (552 µmol mol−1[CO2]) using Free‐Air CO2 Enrichment (FACE) technology. The diurnal courses of leaf CO2 uptake (A) and stomatal conductance (gs) for upper canopy leaves were followed throughout development from the appearance of the first true leaf to the completion of seed filling. Across the growing season the daily integrals of leaf photosynthetic CO2 uptake (A′) increased by 24.6% in elevated [CO2] and the average mid‐day gs decreased by 21.9%. The increase in A′ was about half the 44.5% theoretical maximum increase calculated from Rubisco kinetics. There was no evidence that the stimulation of A was affected by time of day, as expected if elevated [CO2] led to a large accumulation of leaf carbohydrates towards the end of the photoperiod. In general, the proportion of assimilated carbon that accumulated in the leaf as non‐structural carbohydrate over the photoperiod was small (< 10%) and independent of [CO2] treatment. By contrast to A′, daily integrals of PSII electron transport measured by modulated chlorophyll fluorescence were not significantly increased by elevated [CO2]. This indicates that A at elevated [CO2] in these field conditions was predominantly ribulose‐1,5‐bisphosphate (RubP) limited rather than Rubisco limited. There was no evidence of any loss of stimulation toward the end of the growing season; the largest stimulation of A′ occurred during late seed filling. The stimulation of photosynthesis was, however, transiently lost for a brief period just before seed fill. At this point, daytime accumulation of foliar carbohydrates was maximal, and the hexose:sucrose ratio in plants grown at elevated [CO2] was significantly larger than that in plants grown at current [CO2]. The results show that even for a crop lacking the constraints that have been considered to limit the responses of C3 plants to rising [CO2] in the long term, the actual increase in A over the growing season is considerably less than the increase predicted from theory.
Comparative epidemiology ofPyrenopeziza brassicae(light leaf spot) ascospores and conidia from Polish and UK populations
Authors: Karolewski Z. , Evans N. , Fitt B. D. L. , Baierl A. , Todd A. D. , Foster S. J. 
Published: December 2004

Despite differences in climate and in timing of light leaf spot epidemics between Poland and the UK, experiments provided no evidence that there are epidemiological differences between populations ofPyrenopeziza brassicaein the two countries. Ascospores of Polish or UKP. brassicaeisolates germinated on water agar at temperatures from 8 to 24°C. After 12 h of incubation, percentages of ascospores that germinated were greatest at 16°C: 85% (Polish isolates) and 86% (UK isolates). The percentage germination reached 100% after 80 h of incubation at all temperatures tested. The rate of increase in germ tube length increased with increasing temperature from 8 to 20°C but decreased from 20 to 24°C, for both Polish and UK isolates. Percentage germination and germ tube lengths of UKP. brassicaeascospores were less affected by temperature than those of conidia.P. brassicaeproduced conidia on oilseed rape leaves inoculated with ascospores or conidia of Polish or UK isolates at 16°C with leaf wetness durations from 6 to 72 h, with most sporulation after 48 or 72 h wetness. Detection of both mating types ofP. brassicaeand production of mature apothecia on leaves inoculated with mixed Polish populations suggest that sexual reproduction does occur in Poland, as in the UK.
Reproductive Performance of Thoroughbred Mares in Sweden
Authors: Hemberg E , Lundeheim N , Einarsson S 
Published: December 2004

ContentsDuring 1997–2001, a total of 430 Thoroughbred mares were mated by one of the two Thoroughbred stallions on a well‐managed stud farm in the central part of Sweden. On arrival, a thorough gynaecological examination of all mares was performed. An early pregnancy examination was performed on days 14 and 15 after ovulation. The overall conception rates for the two stallions were 92.2 and 88.8%, and the corresponding live foal rates were 82.6 and 75.2%, respectively. The mean number of served oestrous cycles was 1.60 per mare per conception and 1.86 per live foal. The first and second cycle conception rates are reported for different age groups, mare categories and month of mating. The age of the mares had a significant influence on the live foal rate, being lower for mares >13 years of age. Resorption and abortion occurred in higher percentages among mares >8 years of age. The highest embryonic death occurred among mares with a history of being barren, or with having resorbed or aborted foetuses during the previous season. The month of mating had no significant influence on the first cycle conception rate or the second cycle conception rate. The frequency of twinning was 10.5% and the results of manual crushing of one of the conceptuses was successful in 88.9% of all cases, according to the ultrasound scanning 2 days later.
Effects of Developmental Stage, Embryonic Interferon‐τ Secretion and Recipient Synchrony on Pregnancy Rate after Transfer of in vitro Produced Bovine Blastocysts
Authors: Kubisch HM , Sirisathien S , Bosch P , Hernandez‐Fonseca HJ , Clements G , Liukkonen JR , Brackett BG 
Published: December 2004

ContentsThree separate trials of bovine embryo transfers were performed consisting of 32, 41 and 33 transfers, respectively, to examine the effects of (a) the developmental stage of in vitro‐derived blastocysts, (b) the amount of interferon‐τ (IFN‐τ) they secreted during culture and (c) the cyclic stage of the recipient at the time of transfer on the probability of establishment of pregnancy. One blastocyst was transferred into the ipsilateral uterine horn to the CL. At the time of transfer, blastocysts were classified into one of three developmental stages (early blastocyst, blastocyst and expanded blastocyst) and the cyclic stage of each cow was assessed (−12 h, on time, +12 h, +24 h, >24 h). Prior to the second and third trials, blastocysts were individually cultured for 24 h in 50 μl medium droplets and the IFN‐τ concentration in the droplet was determined. Logistic regression analyses revealed that expanded blastocysts had a significantly higher likelihood of establishing pregnancy (p = 0.009), and that there was a significant interaction with the cyclic stage of the recipient in this group with lower rates of pregnancy resulting from decreasing synchrony with the recipient (p = 0.033). IFN‐τ secretion during culture was significantly higher in expanded blastocysts than in the other two groups (p < 0.05). A significant effect of the pre‐transfer level of IFN‐τ secretion was found only in the ‘Blastocyst’ group where transfer of embryos with lower IFN‐τ production prior to transfer resulted in higher pregnancy rates (p = 0.047). These results demonstrate that IFN‐τ secretion may be a useful tool to predict pregnancy outcome, but only within certain developmental stages.
Use of spinal anaesthesia in paediatric patients: a single centre experience with 1132 cases
Authors: Puncuh Franco , Lampugnani Elisabetta , Kokki Hannu 
Published: December 2004

SummaryBackground : Spinal anaesthesia has been used in children for over 100 years and in the last two decades its popularity for newborns and infants has increased, but there are still unanswered questions with the technique.Methods : We evaluated the characteristics of spinal block including ease of performance, efficacy, adverse effects and complications in 1132 children, aged 6 months to 14 years, undergoing surgery in the lower part of the body. Local ethical committee approved the protocol of this prospective study, and parents gave written informed consent and older children their assent. All patients were sedated with midazolam, thiopental or propofol intravenously during spontaneous ventilation. No inhalation anaesthetics were used. Spinal block was performed with 0.5% hyperbaric bupivacaine at a dose of 0.2 mg·kg−1.Results : Efficacy, safety and ease of performance of the spinal block were shown to be satisfactory in most children. Only 27 of the 1132 children needed any supplementation. The incidence and severity of complications was low. Only nine of 942 children, <10 years of age and eight of 190 children, 10 years or older, developed hypotension. The incidences of postdural puncture headache, in five of the 1132 children, and backache, in nine of the 1132, were low. No other neurological complications were reported.Conclusions : Spinal anaesthesia with hyperbaric bupivacaine is a feasible anaesthetic method in children for surgery in the lower part of the body.
Anaesthesia induction in children: a psychological evaluation of the efficiency of parents’ presence
Authors: Messeri Andrea , Caprilli Simona , Busoni Paolo 
Published: December 2004

SummaryBackground : The induction of anaesthesia for surgery is a stressful time for both child and parents. To treat preoperative anxiety in children, pharmacological methods (premedication) and behavioural methods (the presence of parents during the induction of anaesthesia) have been used, both independently and in combination.The purpose of this investigation was to study the effect of both premedication and parental presence on preoperative anxiety in a homogeneous population.Methods : In this study conducted between January and April 2001 in the Meyer Hospital in Florence (Anaesthesia Department and Surgical Department), we studied 39 Italian speaking children aged 2–14 years who were undergoing minor surgery. Before the surgical intervention the State Trait Anxiety Inventory (STAI) questionnaire and a questionnaire for the social‐demographic characteristics were given to the parents. The stress of the children was evaluated during induction of anaesthesia. We also studied behavioural areas of both children and parents with two specific questionnaires administered after the surgery.Results : The STAI scores showed that the mothers had a higher level of anxiety compared with the fathers. The induction of anaesthesia for surgery was a stressful time for 23% of children of our sample. The correlation between stress of the child at induction and state (P = 0.034) and trait (P = 0.049) anxiety of parents was statistically significant. The child's loss of consciousness was for the majority of parents (56%) the moment of greatest stress and 97% of parents did feel useful during the induction of anaesthesia. There was a significant difference, P = 0.032, in the presence or absence of stress depending on whether the mother or father accompanied the child to the operating room. There was no significant difference in the presence of stress between children who did and did not receive premedication.Conclusions : Maternal presence, compared with the father's presence, is fundamental in helping to overcome anxiety in a child receiving anaesthesia. If the parents are present during the induction, the addition of premedication does not offer further benefit. Parents themselves judged their presence during the induction of anaesthesia in their child as a positive event. We also found a statistical significant correlation between anxiety of the parents with the level of the stress of the child during induction of anaesthesia.
Hypercapnia: what is the limit in paediatric patients? A case of near‐fatal asthma successfully treated by multipharmacological approach
Authors: Mazzeo Anna Teresa , Spada Antonella , Praticò Caterina , Lucanto Tullio , Santamaria Letterio Bruno 
Published: December 2004

SummaryWe describe a case of prolonged severe hypercapnia with respiratory acidosis occurring during an episode of near‐fatal asthma in an 8‐year‐old boy, followed by complete recovery. After admission to the intensive care unit, despite treatment with maximal conventional bronchodilatative therapy, the clinical picture deteriorated with evident signs of respiratory muscle fatigue. The child was sedated, intubated and mechanically ventilated. Magnesium sulphate, ketamine and sevoflurane were gradually introduced together with deep sedation, curarization and continuous bronchodilatative therapy. Ten hours after admission, arterial pCO2 reached 39 kPa (293 mmHg), pH was 6.77 and pO2 8.6 kPa (65 mmHg). Chest radiograph showed severe neck subcutaneous emphysema, with signs of mediastinal emphysema. No episode of haemodynamic instability was seen despite severe prolonged hypercapnia lasting more than 14 h. Oxygenation was maintained and successful recovery followed without neurological or cardiovascular sequelae. This case shows the cardiovascular and neurological tolerance of a prolonged period of supercarbia in a paediatric patient. The most important lesson to be learned is the extreme importance of maintaining adequate tissue perfusion and oxygenation during an asthma attack. The second lesson is that when conventional bronchodilators fail, the intensivist may resort to the use of drugs such as ketamine, magnesium sulphate and inhalation anaesthesia. In this context deep sedation and curarization are important not only to improve oxygenation, but also to reduce cerebral metabolic requirements.
Cre‐mediated site‐specific gene integration for consistent transgene expression in rice
Authors: Srivastava Vibha , Ariza‐Nieto Magnolia , Wilson Andrea J. 
Published: December 2004

SummaryTo minimize expression variability amongst transgenic lines, we have utilized the strategy of Cre/lox‐mediated site‐specific gene integration. This method allows the precise integration of a transgene in a lox site previously placed in the genome. Using the biolistic method for DNA delivery, we have generated several site‐specific integrant lines, derived from three different target lines. About 80% of the selected lines contain precise integration of the gusA reporter gene and fall into two categories: single‐copy (SC) lines that contain site‐specific integration without additional random integrations, and multicopy (MC) lines that contain random integrations in addition to the site‐specific integration. The expression of the gusA gene was studied in callus cells and regenerated plants. The isogenic SC lines displayed significantly lower expression variation, whereas much higher expression variation was observed in MC lines. Furthermore, stable inheritance of the gusA gene was observed in T1 plants derived from a subset of SC lines. This demonstrates that consistent gene expression can be obtained in rice by Cre‐mediated site‐specific integration.