Seasonality ofOrmia depletaand Limits to Its Spread

Ormia depleta(Wiedemann) (Diptera: Tachinidae), a South American fly that homes on the calling songs of its hosts, was brought from Piracicaba, Brazil; colonized; and released in Florida for the biological control ofScapteriscusspp. mole crickets. It became established at some release sites and rapidly spread through most of peninsular Florida. The seasonal distributions of phonotactic females in Florida differed from the single summer peak recorded at Rio Claro and Piracicaba, Brazil (23° S). Near Bradenton (27° N), spring and fall peaks with a summer hiatus were quickly established and remain evident. At two sites near Gainesville (30° N), a strong fall peak and a modest-to-none spring peak developed. Peaks of phonotactic females seem to follow times of peak host availability and sometimes coincide with minima of host availability. Limits to geographical expansion ofO. depletaare poorly understood. At Gainesville, the site of earliest introduction, establishment was rapid and soundtrap catches increased for the first 3 years, exceeding 1000 per year at one site. Catches then declined for 3 years, almost reaching zero in 1994. On the other hand, annual sound-trap catches ofO. depletaat Bradenton exceeded 1000 in <2 years and have remained above that level for 5 years. Winters in Gainesville are more severe than those in Bradenton, but minimum winter temperatures in Gainesville were substantially lower duringO. depleta's increase than during its decline. Perhaps mild winters cause the flies to become active early—only to starve for lack of adequate winter nectar sources.O. depletamay yet spread to the northern limits of itsScapteriscushosts as present populations adapt to new environments. Or farther spread may require that new strains be introduced from more southerly sites in South America.     

The control of respiration in wheat (Triticum aestivum L.) leaves

The aim of this work was to discover whether the respiration of wheat (Triticum aestivum L. cv. Huntsman) leaves, transferred to darkness after 7 h photosynthesis, showed an initial period of wasteful respiration. For young and old leaves, CO₂ production and O₂ uptake after 7 h photosynthesis were up to 56% higher than at the end of an 8-h night. The maximum catalytic activities of citrate synthase (EC 4.1.3.7), aconitase (EC 4.2.1.3), fumarase (EC 4.2.1.2) and cytochrome-c oxidase (EC 1.9.3.1) at the end of the day did not differ from those at the end of the night. Changes in the contents of glucose 6-phosphate, fructose-1,6-bisphosphate, dihydroxyacetone phosphate, and -ketoglutarate did not as a group parallel the changes in the rate of respiration. The detailed distribution of label from [U-¹⁴C] sucrose supplied to leaves in the dark was similar at the end of the day and the end of the night. No correlation was observed between the rates of leaf respiration and extension growth. It is argued that the higher rate of respiration at the beginning of the night cannot be attributed to wasteful respiration.Abbreviation RQ respiratory quotient We thank Dr H. Thomas and Professor C.J. Pollock, Institute for Grassland and Environmental Research, Plas Gogerddan, Aberystwyth, UK for their generous help in measuring leaf extension. R.H.A. thanks the Science and Engineering Research Council for a studentship.     

Skeletal muscle: A paradigm for testing principles of bioenergetics

Muscular activity converts chemical energy into useful work and metabolism restores muscle to its original state. This essay explores the organization and interactions of the regulatory system(s) which allow this energy balance to occur. The term energy balance is used in a biochemical rather than a thermodynamic sense—concerned not with deductions from the physical principles of thermodynamics, but rather with those enzymatic processes which nature evolved and which operate at remarkably fixed stoichiometry. Energy balance is a statement of conservation of energy put into biochemical observables.³¹P NMR spectroscopy is one of the most useful techniques for investigating these questions quantitatively under physiological conditionsin vivo. The author (1) describes the rules or principles of biochemical energy balance; (2) discusses sample results from human muscle to demonstrate its use in studying this class of questions; (3) presents a simple model of integrated cellular respiration to demonstrate its sufficiency to account for the main observations.     

Regulation of energy metabolism in liver

Energy metabolism in liver has to cope with the special tasks of this organ in intermediary metabolism. Main ATP-generating processes in the liver cell are the respiratory chain and glycolysis, whereas main ATP-consuming processes are gluconeogenesis, urea synthesis, protein synthesis, ATPases and mitochondrial proton leak. Mitochondrial respiratory chain in the intact liver cell is subject to control mainly by substrate (hydrogen donors, ADP, oxygen) transport and supply and proton leak/slip. Whereas hormonal control is mainly on substrate supply to mitochondria, proton leak/slip is supposed to play an important role in the modulation of the efficiency of oxidative phosphorylation.     

An evaluation of ‘rapid review’ as a method of quality control of cervical smears using the AxioHOME microscope

An evaluation of ‘rapid review’ as a method of quality control of cervical smears using the AxioHOME miscroscope One method of quality control which has recently been recommended by professional bodies in the UK is the ‘rapid review’ method. This involves the microscopic 30 s review of all negative cervical smears with the intention of flagging potential missed abnormalities. Although it has been suggested that rapid review is better than 10% random rescreening of negative smears, the efficiency and efficacy of this method of quality control have not been thoroughly evaluated. We have used the AxioHOME system, which can record the area of a slide covered and the screening time, to investigate slide coverage during rapid review quality control, as performed by 15 cytoscreeners and MLSOs reviewing a test set of 22 slides each. The test set comprised 18 negative slides, three positive slides, and one unsatisfactory slide. We have recorded two distinct methods of rapid review in use amongst cytotechnologists, the step method and the whole slide method. The data show that rapid review takes longer on average than the recommended 30 s, the mean screening times being 76 s and 82 s for the step and whole slide methods, respectively. Abnormal smears were missed on three of 15 occasions by the step method (sensitivity 80%, positive predictive value 85%), and on seven of 30 occasions by the whole slide method (sensitivity 76.6%, positive predictive value 45%). However, the 95% confidence intervals were wide (57.7–90.7% for the step method, and 51.9–95.7% for the whole slide method). Analysis of scanning tracks and screening rates shows significant flaws in the methodology of rapid review. Abnormal cells were not identified, although dyskaryotic cells were included in the scanning track on nine occasions, seven using the whole slide method and two using the step method. On one occasion (using the step method) abnormal cells were not identified because they were not included in the scanning track. Further research is in progress to determine optimal methods of rapid review, and whether the rapid review technique is as effective as automated screening systems for quality assurance in cytology. Evaluation de la technique de ‘Relecture Rapide’ comme méthode de contrôle de qualité des frottis cervico-utérins, à l'aide du microscope AxioHOME Une des méthodes de contrôle de qualité récemment recommandée par le corps professionnel du Royaume Uni est la méthode dite de ‘relecture rapide’. Cette méthode consiste en une deuxième lecture d'une durée de trente secondes de tous les frottis cervicaux négatifs et dont l'objectif est de détecter les anomalies ayant pu échapper au premier examen. Bien qu'il ait été suggéré que cette méthode de relecture rapide soit meilleure que la relecture de 10% des frottis négatifs tirés au sort, le rendement et l'efficacité de cette méthode de contrôle de qualité n'ont pas été évalués complètement. Nous avons utilisé le système AxioHOME capable d'enregistrer la plage de la lame qui a été explorée ainsi que le temps de lecture afin d'étudier la surface explorée au cours de cette relecture rapide telle qu'elle a pu être pratiquée par quinze cytotechniciens et MLSOs, chacun ayant relu une série test de vingt deux lames. Cette série test comprenait dix huit lames négatives, trois lames positives et un frottis non satisfaisant. Nous avons noté que les cytotechniciens utilisaient deux méthodes de relecture rapide différentes, la méthode ‘pas à pas’ et la méthode ‘globale’. Les données montrent que la relecture rapide prend, en moyenne, un temps supérieur aux trente secondes recommandées, la moyenne des temps de lecture étant de 76 secondes et de 82 secondes respectivement pour la méthode ‘pas à pas’ et la méthode ‘globale’. Les anomalies n'ont pas été détectées dans trois cas sur quinze par la méthode ‘pas à pas’ (sensibilité 80%, valeur prédictive positive 85%), et dans 7 cas sur 30 par la méthode globale (sensibilité 76,6%, valeur prédictive positive 45%). Toutefois, l'intervalle de confiance à 95% est important (57,7%-90,7% pour la méthode ‘pas à pas’ et 51,9%-95,7% pour la méthode globale). L'analyse des surfaces balayées et des taux de détection montre des points faibles significatifs de cette méthodologie de relecture rapide. Dans 9 cas, les anomalies n'ont pas été identifiées alors que des cellules dyskaryotiques étaient présentes dans les plages balayées au cours de la relecture (sept utilisant la méthode globale et deux utilisant la méthode ‘pas à pas’). Dans un cas (avec la méthode ‘pas à pas’) les cellules anormales n'ont pas été identifiées parce qu'elles étaient absentes des plages de relecture. Des études sont en cours afin de déterminer quelles sont les méthodes optimales de relecture rapide et si ces techniques de relecture rapide sont aussi efficaces que les systèmes de lecture automatisée pour l'assurance de qualité en cytologie cervico-utérine. ‘Rapid Review’ als Methode der Qualitätskontrolle gynäkologischer Abstriche, Überprüfung mit dem AxioHOME-Mikroskop Die empfohlene ‘Rapid Review’ Kontrolle aller negativen Abstriche in nur 30 Sekunden anstelle des Nachscreenens von 10% der Präparate ist in ihrer Zuverlässigkeit bislang nicht überprüft worden. Mit Hilfe des AxioHOME-Mikroskops ist es möglich sowohl die ausgewertete Fläche, als auch die erforderliche Zeit zu erfassen. 15 Auswerter prüften mit der Methode jeweils einen Testsatz von 22 Präparaten. Er enhielt 18 negative, 3 positive und 1 nichtauswertbaren Abstrich. Getestet wurden zwei verschiedene Vorgehensweisen: die schrittweise und die das ganze Präparat erfassende. Beide erfordern mehr Zeit als 30 Sekunden; der mittlere Zeitaufwand betrug für die Schrittmethode 76 und für die Ganzheitsmethode 82 Sekunden. Die Schrittmethode verfehlte 3/15 Anomalien (Sensitivität 80%, positiver prädiktiver Wert 85%), die Ganzheitsmethode 7/30 (Sensitivität 76,6%, positiver prädiktiver Wert 45%). Der 95% Konfi denzbereich reichte für die Schrittmethode von 57,5–90,7% und für die Ganzheitsmethode von 51,9–95,7%). Die Analyse deckt wesentliche Schwachstellen des Rapid Review-Verfahrens auf. In 9 Fällen lagen nicht erkannte Zellatypien in den kontroll ierten Bahnen (7 bei des Schrittmethode, 2 bei der Ganzheitsmethode). Einmal lagen sie bei der Schrittmethode ausserhalb der geprüften Bahnen. Weitere Studien werden prüfen ab das Rapid Review-Verfahren automatisierten Systemen vergleichbar ist.     

Recent advances in plant cell cultures in bioreactors

Two key issues in the application of plant-cell-culture technology to the production of valuable secondary metabolites are reviewed: the selection of cell lines with suitable genetic, biochemical and physiological characteristics; and the optimization of bioreactor environments. Although great progress has been made in recent years in the design, selection and optimization of bioreactor hardware, optimization of environmental factors such as medium components, light irradiation and O₂ supply needs detailed investigations for each case. With a better understanding of plant cell metabolism and physiology, further developments in cultivation processes, such as process integration and on-line monitoring and control, can be expected in the near future.J.-J. Zhong and J.-T. Yu are with the Research Institute of Biochemical Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China T. Yoshida is with the International Center of Cooperative Research in Biotechnology (ICBiotech), Faculty of Engineering, Osaka University, Suita, Osaka 565, Japan.     

Schistosoma mansoni: differences in acetylcholine, dopamine, and serotonin control of circular and longitudinal parasite muscles

The physiological and pharmacological properties of circular and longitudinal somatic musculature in adult male Schistosoma mansoni were compared using cut muscle sections. Carbachol reduced tone in both circular and longitudinal muscle, but was without effect on circular muscle bathed in high Mg2+, indicating that cholinergic receptors were not associated with circular muscle membrane. 5-Hydroxytryptamine (5-HT) induced rhythmic contractile activity in both sets of muscle. It decreased muscle tone in circular muscle but increased the tone of longitudinal muscle. Metergoline blocked 5-HT effects on both sets of muscle. 5-HT continued to be effective on both sets of muscle bathed in high-Mg2+ medium, indicating that serotonergic receptors were present on both circular and longitudinal muscle membranes. Dopamine decreased both circular and longitudinal muscle tone. Its effects on circular muscle were still present after exposure to high Mg2+, but its effects on the longitudinal muscle were significantly reduced, leading to the conclusion that dopaminergic sites were probably associated with circular muscle membrane but not that of longitudinal muscle. Also, spiroperidol blocked stimulus responsiveness of the circular muscle but not that of the longitudinal muscle. From these studies it appears that there are significant physiological and pharmacological differences between circular and longitudinal muscles in the adult male schistosome.     

The adaptive pattern of growth and reproduction of the colonial hydroid Clavopsella michaeli

The effects of variations in temperature, salinity and water movement on the laboratory growth and reproduction of a single clone of the bougainvilliid hydroid Clavopsella michaeli were examined. Unfavourable conditions resulted in reproducible oscillations of growth rate. They ranged from overall stimulatory effects (hormesis) to irreversible inhibition and shrinkage of colonies. Exposure to low concentrations (0.1–5 µg l^–1) of copper and mercury ions produced similar responses, which were therefore regarded as non-specific. A control mechanism, dampening these growth rate oscillations, supported higher colonial tolerance, that is adaptation, to environmental stresses of low intensity. When the counteractive capacity of the control mechanism was exceeded, inhibition occurred. Higher frequencies of gonozooids were observed in stressed colonies and were interpreted as an adaptive response.     

The involvement of mycorrhizas in assessment of genetically dependent efficiency of nutrient uptake and use

This article summarises the way in which mycorrhizal infection of roots affects the mineral nutrition of plants and how the symbiosis may interact with the evaluation of efficiency of nutrient uptake and use by plants. A brief account of the processes of infection and the way they are affected by host genotype and environmental conditions is given and the relationships between this and mineral nutrition (especially phosphate nutrition) are outlined.The interactions between mycorrhizal infection and P efficiency are considered at two levels. Mycorrhizas may act as general modifiers of efficiency regardless of the extent to which the plants are infected and in some mycorrhiza-dependent plants infection may change the ranking of genotypes. The extent of infection is also under genetic control and shows considerable variability between genotypes in some species. This variation could be used in programs to select varieties in which infection is rapid and nutrient uptake from nutrient deficient or low input systems is, in consequence, increased.