bluuebunny/crossref_metadata_2025_split huggingface dataset:
Determination of allatostatin levels in relation to the gonadotropic cycle in the female of Blattella germanica (L.) (Dictyoptera, Blattellidae)
Authors: Vilaplana Lluïsa , Maestro José. L. , Piulachs Maria‐Dolors , Bellés Xavier 
Published: March 2003

SummaryA polyclonal antibody against the allatostatin BLAST‐3 (AGSDGRLYSFGL‐NH2) of the cockroach Blattella germanica (L.) (Dictyoptera, Blattellidae) has been raised and characterized, and an ELISA (enzyme‐linked immunosorbent assay) for allatostatin quantification has been developed. Allatostatin contents in brain, midgut and haemolymph have been measured in females of B. germanica during the first gonadotropic cycle. Brain allatostatin content increases steadily from adult emergence to the formation of the first ootheca. The values range from 2 ng/brain on the day of adult emergence to 25 ng/brain when the insect forms the ootheca 8 days later. In the midgut, the pattern is similar but the values are about half those of the brain. Allatostatin concentrations in the haemolymph after HPLC separation are in the nanomolar range. The occurrence of allatostatins in the haemolymph suggests that these peptides can act through a humoral pathway, as well as via nerves. The allatostatin content of both brain and midgut are high while the female is transporting the ootheca, which suggests that these peptides could be related to the low metabolic status characterising the period of oothecal transport.
Nutritional requirements for web synthesis in the tetragnathid spider Nephila clavipes
Authors: Higgins Linden , Rankin MarY. AnN. 
Published: March 2003

SummaryTrap‐constructing organisms provide a unique opportunity for the study of resource allocation, because an observer can unambiguously determine the allocation to foraging. In species that synthesize a trap from physiologically important compounds, there is the further advantage that there may be direct trade‐offs between allocation of resources to foraging and physiological functions. We examined the ability of the spider Nephila clavipes (L.; Araneae: Tetragnathidae) to synthesize resources that are known to be used for both web synthesis and non‐foraging physiological functions. We found that choline, required for both web function and physiological function, is an essential nutrient: it is not synthesized by this spider. Under laboratory conditions with a diet of fruit flies, choline is limiting, and the spiders make allocation trade‐offs between investing choline in foraging (the web) or in their body.
Behavioural and physiological responses to conflicting oviposition stimuli in a synovigenic parasitoid
Authors: Gauthier N. , Monge J. P. 
Published: March 2003

AbstractThe behavioural and physiological responses of the synovigenic parasitoid, Dinarmus basalis (Rond.) (Hymenoptera: Pteromalidae), were investigated whilst the wasps were submitted to conflicting oviposition stimuli: an environment which induced them to restrict egg‐laying and a physiological factor, egg‐load pressure, which induced them to lay eggs. When individual females depleted patches containing hosts parasitized 24 h or 72 h beforehand, they laid preferentially on unparasitized hosts and the number of eggs laid decreased significantly. Although they remained for several days in such patches, egg‐load pressure did not lead them to modify their strategy (i.e. to accept all the available hosts including the already parasitized ones). In this synovigenic species, the oviposition constraint resulted in the retention of oocytes. Dissection and histological observation showed that the unlaid eggs are resorbed, a reproductive regulatory process which has seldom previously been reported in the presence of unparasitized hosts. This physiological response was induced by the mere presence of the parasitized hosts rather than their density. The females’ response was also influenced by the presence of conspecifics. They still avoided laying on parasitized hosts but the number of eggs laid daily became comparable to that observed in patches containing only unparasitized hosts. Thus, D. basalis females adapted their strategy in response to their environment, in which the most significant factor seemed to be the quality of the hosts provided, and their physiology. The originality and the importance of these results are discussed.
Stage‐specific effects of temperature and dietary protein on growth and survival of Manduca sexta caterpillars
Authors: Petersen C.H.ristine , Woods H. Arthur , Kingsolver J.O.E.L. G. 
Published: March 2003

SummaryThe effects of temperature and dietary protein concentration on growth and survival of Manduca sexta L. (Lepidoptera: Sphingidae) caterpillars during different larval stages were examined. Sets of caterpillars were raised from hatching at one of five constant temperatures (18, 22, 26, 30 or 34°C) and on one of two artificial diets (low or high protein concentration). Mass gain, duration (development time) and mean growth rate were measured for each caterpillar for the 1st to 3rd stadia, the 4th stadium, and the 5th stadium. Temperature significantly affected mass gain during each larval stage, resulting in smaller mass gains at higher temperatures at each stage. This effect was strongest at high temperatures during the 5th stadium. Temperature significantly affected durations of each larval stage, but the effect varied among stages: for example, the duration of stadia 1–3 decreased continuously with increasing temperature, whereas the duration of the 5th stadium was shortest at 26–30°C and increased at lower and higher temperatures. The effect of temperature on mean growth rate changed dramatically across larval stages: maximal growth rate occurred at 34°C during the 1st to 3rd stadia, at 30°C during the 4th stadium and at 26°C during the 5th stadium. Higher dietary protein concentration significantly decreased the duration of stadia 1–3 and of the 4th stadium, but had no significant effect on the duration of the 5th stadium. Temperature and dietary protein had little effect on mortality rates during any larval stadium, with one exception: mortality during the 5th stadium increased dramatically at temperatures of 30 and 34°C. These results demonstrate that the effects of temperature and dietary protein concentration on growth, development and survival in M. sexta vary markedly in different larval stadia during development; 5th instar caterpillars are particularly sensitive to higher temperatures.
Host‐selection behaviour by genetically identical aphids with different plant preferences
Authors: Powell G.L.E.N. , Hardie J.I.M. 
Published: March 2003

SummaryThe behaviour of summer and autumn winged forms of the black bean aphid, Aphis fabae Scopoli (Homoptera: Aphididae), was compared on two plants utilized at different stages of the insect’s life cycle. Adult autumn migrants (gynoparae) are monophagous, colonizing spindle (Euonymus europaeus), whereas polyphagous summer winged aphids (alate virginoparae) are associated with a variety of herbaceous plants, including broad bean (Vicia faba). When aphids from a single clone were given access to a spindle leaf and a bean seedling in choice tests, many virginoparae settled and larviposited on both plant species over 24 h. By contrast, gynoparae showed a clear preference for spindle, with 93.5% of settled adults and 98.3% of larvae on this plant species. Close‐up video monitoring showed that gynoparae discriminated beans from spindle within a 5‐min period, whereas virginoparae behaved similarly on both plant species. For gynoparae, the major behavioural difference on the two plants appeared after a brief (epidermal) stylet penetration, with many insects taking flight within a few seconds of stylet withdrawal from bean. Factors detected during stylet insertion by gynoparae must therefore inhibit take‐off on spindle. Electrical recording experiments showed that aphids often punctured a cell membrane during brief probes on both plant species, and intracellular stylet activities always included a waveform associated with ingestion. When gynoparae puncture spindle cells their behaviour is probably modified by intracellular metabolites detected via gustation of ingested epidermal cell sap. These cues may inhibit the take‐off reflex which otherwise follows probing.
Cold tolerance, overwintering and establishment potential of Thrips palmi
Authors: McDonald Jamie R. , Head Justine , Bale Jeffrey S. , Walters Keith F. A. 
Published: March 2003

SummaryThe cold tolerance and overwintering survival of the quarantine regulated pest and virus vector, Thrips palmi (Karny) (Thysanoptera: Thripidae), is examined and discussed in terms of its establishment potential in the U.K. Thrips palmi adults and first‐instar larvae have a wide distribution of supercooling points (SCPs) but show ‘pre‐freeze’ mortality as a result of both acute and chronic exposures to temperatures above the SCP range. Thrips palmi did not develop enhanced cold tolerance in response to cues previously shown to cold‐acclimate other thrips species. The acute cold tolerance of T. palmi is higher than that of the recently established and biologically similar species, Frankliniella occidentalis, which is thought to be capable only of very limited winter survival outdoors in the U.K. However, the more ecologically meaningful chronic assays reveal the opposite pattern. If introduced to the U.K., overwintering of T. palmi would thus be largely restricted to protected environments, as its cold tolerance is insufficient to permit outdoor survival for a complete winter. This assertion was demonstrated by caged populations that died out after as little as 25 days in outdoor winter conditions in Yorkshire, U.K. The reversal of relative tolerance of the two species when considering chronic and acute assays suggests that these forms of low temperature mortality have different physiological bases, and emphasizes the need to use both forms of assay in assessments of overwintering capacity.
Structure of host‐odour plumes influences catch of Anopheles gambiae s.s. and Aedes aegypti in a dual‐choice olfactometer
Authors: Dekker Teun , Takken Willem , Cardé Ring T. 
Published: March 2003

SummaryThe effects of structure, concentration and composition of host‐odour plumes on catch of female Anopheles gambiae Giles sensu stricto and Aedes aegypti (L.) (Diptera: Culicidae) were investigated in a dual‐choice olfactometer. We demonstrate that the fine‐scale structure of host‐odour plumes modulates capture of An. gambiae and Ae. aegypti. In both species homogeneous skin‐odour plumes result in trap entry, whereas homogeneous CO2 plumes reduce trap catch. Reduced trap catch also result from combining skin odour with a homogeneous CO2 plume. Trap capture rates in homogeneous CO2 plumes were concentration‐dependent and differed between the two species. Electric nets placed in front of the trap entrances intercepted mosquitoes before they could enter the traps. This showed that An. gambiae flew along CO2 plumes, but did not enter the traps. Survivorship analysis of the trap‐entry times of Ae. aegypti indicated interactions between the time until capture and treatment. The assay's duration therefore can alter the distribution in a dual‐choice olfactometer.
Potential mechanism for detection by Apis mellifera of the parasitic mite Varroa destructor inside sealed brood cells
Authors: Martin Caroline , Provost Eric , Bagnères Anne‐Geneviève , Roux Maurice , Clément Jean‐Luc , Le Conte Yves 
Published: March 2003

Abstract The parasitic mite Varroa destructor Anderson & Trueman is a major pest of the honeybee Apis mellifera L. throughout the world. Chemical agents currently used for mite control leave contaminating residues and promote pesticide resistance. As an alternative means of control, it would be useful to identify natural substances enabling bees to detect Varroa inside brood cells. These substances could then be used to trigger mite hygienic behaviour by bees.In this study several techniques were used to screen substances that might allow detection of infested brood cells by bees. Gas chromatography‐mass spectrometry analysis was performed on substances extracted in dichloromethane from the contents of brood cells. Solid phase microextraction and solid injection were performed on substances obtained from living and dead Varroa, respectively. Electroantennography was performed to assess the sensitivity of olfactory receptors in bee antennae to some of these substances.Principal component analysis based on proportions of cuticular substances allowed discrimination between bees and other cell contents. Foundress Varroa exhibited the greatest dissimilarity to healthy pupae that were used as controls. Immature Varroa and faecal material were intermediate. High molecular weight compounds, mainly dimethylalkanes, were proportionally the most characteristic components of foundress Varroa. This finding suggests that these compounds would be the most apt to induce uncapping of cells infested by Varroa. Solid‐phase microextraction and solid injection demonstrated the presence of aliphatic acids, esters, and one alcohol, eicosenol, in Varroa. Electroantennographic recordings showed that mite‐resistant bees were more responsive to some acids and one ester. We speculate that these compounds may be involved in recognition of living Varroa by honeybees.
Use of thermography for quantitative studies of spatial and temporal variation of stomatal conductance over leaf surfaces
Authors: Jones H. G. 
Published: March 2003

ABSTRACTThis paper describes a new approach to the calibration of thermal infrared measurements of leaf temperature for the estimation of stomatal conductance and illustrates its application to thermal imaging of plant leaves. The approach is based on a simple reformulation of the leaf energy balance equation that makes use of temperature measurements on reference surfaces of known conductance to water vapour. The use of reference surfaces is an alternative to the accurate measurement of all components of the leaf energy balance and is of potentially wide application in studies of stomatal behaviour. The resolution of the technique when applied to thermal images is evaluated and some results of using the approach in the laboratory for the study of stomatal behaviour in leaves of Phaseolus vulgaris L. are presented. Conductances calculated from infrared measurements were well correlated with estimates obtained using a diffusion porometer.
Stress tolerance and reactive oxygen metabolism in the intertidal red seaweeds Mastocarpus stellatus and Chondrus crispus
Authors: Collén J. , Davison I. R. 
Published: March 2003

ABSTRACT Mastocarpus stellatus and Chondrus crispus are morphologically similar red seaweeds that co‐occur on rocky intertidal seashores in the Northern Atlantic. Mastocarpus stellatus grows higher on the shore and is more tolerant of environmental stress, caused by factors such as freezing and desiccation, than C. crispus. Here we report a correlation between reactive oxygen metabolism and stress tolerance, which suggests that reactive oxygen metabolism may play a role in stress tolerance of intertidal red seaweeds. Mastocarpus stellatus scavenged added H2O2 slightly faster, and was more resistant to oxidative stress induced by addition of H2O2 and Rose Bengal, than C. crispus. These data were consistent with higher levels of ascorbate and β‐carotene and higher activities of catalase and glutathione reductase, in M. stellatus. Tocopherol content and activities of superoxide dismutase and ascorbate peroxidase were similar in both species. Activities of reactive oxygen scavenging enzymes generally increased with tidal height in M. stellatus; this was, however, not a consistent trend in C. crispus.
An improvement of the method for calibrating measurements of photosynthetic CO2 flux
Authors: Hari P. , Keronen P. , Bäck J. , Altimir N. , Linkosalo T. , Pohja T. , Kulmala M. , Vesala T. 
Published: March 2003

ABSTRACTMeasurements of rapid changes in concentrations and fluxes of gaseous compounds relating to photosynthetic gas exchange are commonly performed using flow‐through cuvettes in connection with infrared gas analysers. The accuracy and repeatability of these measurements relies ultimately upon the design of the system as a whole, rather than upon each of its components, and therefore the calibration and testing of the system should be performed keeping this in mind. We present here a simple and efficient method for the calibration of such a measurement system using a precisely determined CO2 flow. This method gives us the opportunity to take into account any disturbing effects caused by undesired properties of the chamber or tubing materials. With the proposed calibration method, the accuracy of the CO2 flux measurement is improved from 8% up to the level of 2%, determined mainly by the accuracy of the control gas used for calibration of the CO2 analyser.
Inter‐specific variation of the biochemical limitation to photosynthesis and related leaf traits of 30 species from mountain grassland ecosystems under different land use
Authors: Wohlfahrt G. , Bahn M. , Haubner E. , Horak I. , Michaeler W. , Rottmar K. , Tappeiner U. , Cernusca A. 
Published: March 2003

ABSTRACTThe maximum rate of carboxylation (Vcmax) and the potential rate of RuBP regeneration (Pml, which equals Jmax/4), as well as leaf nitrogen content (NL) and specific leaf area (SLA), were studied in sun leaves of 30 species from differently managed mountain grassland ecosystems (abandoned areas, pastures and meadows) at three study areas in the Eastern Alps. A significant correlation between Vcmax and Pml across the investigated species was observed. In comparison to a previous survey on the relationship between Pml and Vcmax, the investigated species were found to invest a proportionally smaller amount of available resources into Pml. Despite this close correlation between Vcmax and Pml, variation in the Vcmax–NL and Pml–NL relationships was large, indicating that the investigated species differed widely in their respective nitrogen use efficiencies. Among the investigated species, dwarf shrubs were characterized by significantly lower values of Vcmax, Pml and NL compared to graminoids and forbs, which did not differ significantly from each other. Species from abandoned areas were found to be lower with respect to Vcmax, Pml, NL and SLA than species from pastures and meadows, which were not significantly different from each other.
Inhibition of ethylene biosynthesis by antisense ACC oxidase RNA prevents chilling injury in Charentais cantaloupe melons
Authors: Ben‐Amor M. , Flores B. , Latché A. , Bouzayen M. , Pech J. C. , Fomojaro F. 
Published: March 2003

ABSTRACTNon‐freezing low temperature storage causes injury to melons and most other fruit and vegetables of tropical and subtropical origin. We demonstrate here that ethylene suppression through an antisense ACC oxidase (ACO) gene considerably reduced the sensitivity of Charentais cantaloupe melons to chilling injury. In contrast to wild‐type fruit, antisense ACO melons did not develop the characteristic chilling injury of pitting and browning of the rind neither when stored at low temperature (3 weeks at 2 °C) nor upon rewarming. Treating antisense melons with 10 p.p.m. ethylene for more than 1 d prior to cold storage resulted in the restoration of chilling sensitivity. When the ethylene treatment was performed after cold storage, the chilling injury symptoms did not appear. The tolerance to chilling was associated with a lower accumulation of ethanol and acetaldehyde, reduced membrane deterioration and higher capacity of the fruit to remove active oxygen species. The activities of catalase, superoxide dismutase and peroxidase were markedly increased in antisense ACO fruit in comparison with wild‐type fruit, particulary upon rewarming and post‐storage ethylene treatment. Severe chilling injury symptoms were correlated with a lower activity of activated oxygen scavenging enzymes. These results demonstrate that ethylene acts in conjunction with low temperature to induce metabolic shifts that participate in the development of chilling injury.
Leaf expansion – an integrating plant behaviour
Authors: Volkenburgh E. Van 
Published: March 2003

ABSTRACTLeaves expand to intercept light for photosynthesis, to take up carbon dioxide, and to transpire water for cooling and circulation. The extent to which they expand is determined partly by genetic constraints, and partly by environmental conditions signalling the plant to expand more or less leaf surface area. Leaves have evolved sophisticated sensory mechanisms for detecting these cues and responding with their own growth and function as well as influencing a variety of whole‐plant behaviours. Leaf expansion itself is an integrating behaviour that ultimately determines canopy development and function, allocation of materials determining relative shoot : root volume, and the onset of reproduction. To understand leaf development, and in particular, how leaf expansion is regulated, we must know at the molecular level which biochemical processes accomplish cell growth. Physiological experimentation focusing on ion fluxes across the plasmamembrane is providing new molecular information on how light stimulates cell expansion in some dicotyledonous species. Genetic analyses in Arabidopsis, corn, and other species are rapidly generating a list of mutations and enzyme activities associated with leaf development and expansion. Combination of these approaches, using informed physiological interpretations of phenotypic variation will allow us in the future to identify genes encoding both the processes causing cell expansion, and the regulators of these events.
AtSTP3, a green leaf‐specific, low affinity monosaccharide‐H+ symporter of Arabidopsis thaliana
Authors: Büttner M. , Truernit E. , Baier K. , Scholz‐Starke J. , Sontheim M. , Lauterbach C. , Huss V. A. R. , Sauer N. 
Published: March 2003

ABSTRACTThis paper describes the expression analyses of the AtSTP3 gene of Arabidopsis thaliana, the functional characterization of the encoded protein as a new monosaccharide transporter, and introduces the AtSTP gene family. The kinetic properties of the AtSTP3 protein (for sugar transport protein 3) were studied in a hexose transport deficient mutant of Schizosaccharomyces pombe. AtSTP3 represents a new monosaccharide transporter that is composed of 514 amino acids and has a calculated molecular mass of 55·9 kDa. Kinetic analyses in yeast showed that AtSTP3 is a low affinity, energy‐dependent H+ symporter with a Km for D‐glucose of 2 mM. RNase protection analyses revealed that AtSTP3 is expressed in leaves and floral tissue of Arabidopsis. This expression pattern of the AtSTP3 gene was confirmed in AtSTP3 promoter‐β‐glucuronidase (GUS) plants showing AtSTP3‐driven GUS activity in green leaves, such as cotelydons, rosette and stalk leaves and sepals. Wounding caused an induction of GUS activity in the transgenic plants and an increase of AtSTP3 mRNA levels in Arabidopsis wild‐type plants. Polymerase chain reaction analyses with degenerate primers identified additional new AtSTP genes and revealed that AtSTP3 is the member of a large family of at least 14 homologous genes coding for putative monosaccharide‐H+ symporters (AtSTPs).