Rapid recording of the fluorescence spectrum emitted by an isolated living cell]

In order to use the selectivity of fluorescence emission for biomedical purposes, a microspectrofluorimeter has been built around an inverted microscope. The excitation is supplied by a 450 W Xenon lamp coupled with a monochromator allowing excitation from 230 to 600 nm. The fluorescence is analysed by a Grism (association prism-grating) and the spectrum focused on the 500 channels of the target of an Optical Multichannel Analyser. Related to good resolution and dispersion (0.44 nm/channel), improvement of signal to noise ratio (dark current suppression, and accumulation of spectra), this microspectrofluorimeter with high sensitivity is well adapted to the study of biological mechanism in single living cells (macrophages, monocytes, lumphocytes).     

Activation of particle associated rat liver guanine deaminase by lecithin and interferences of lecithin in protein precipitation

Summary Guanine deaminase solubilized from the light mitochondrial fraction of rat liver was activated by lecithin. The activation was proportional to the concentration of lecithin taken in the system. A ratio of 11 between the two constituents (protein and lecithin) was at least necessary for complete precipitation.Acknowledgment. The authors are grateful to Professor P.S.Krishnan, University of Calicut, Calicut, Kerala, for his interest.     

Some observations on bipolar filaments formed by non-muscle myosins

Summary Adrenal medullary and retinal myosins formed bipolar filaments in vitro. These filaments showed features suggesting flexibility in the rod region of the myosin molecules composing such filaments; in certain cases the myosin heads spread away from the filament backbone, in others the backbone itself was twisted. In addition the bare central backbone showed transverse striations.We thank G. Devilliers for assistance with electron microscopy, D. Thiersé for technical assistance during purification of adrenal medulla myosin and Professor P. Mandel for his interest and support J.E.H. gratefully acknowledges receipt of a Royal Society European Exchange Fellowship and a grant from INSERM. N.V. is chargée de recherches au CNRS, D.A. is chargé de recherches à l'INSERM.     

Some observations on carotenoid synthesis by the algaChlorella vulgaris

Zusammenfassung WirdChlorella vulgaris in einem Medium, das Glukose, Pepton und Mineralsalze enthält, gezüchtet, so synthetisiert sie sowohl in Licht wie im Dunkeln -Carotin, Lutein, Violaxanthin und Neoxanthin. Das Wachstum im Dunkeln beträgt jedoch nur 1/6 von demjenigen im Licht. Die Carotinoide verschwinden aus alten Lichtkulturen, werden aber in alten Dunkelkulturen weiter synthetisiert. Diphenylamin hemmt das Wachstum dieses Organismus bei einer Konzentration von 1/280 000 vollständig.     

Control charts to check yearly predictions by monthly observations

In many cases an organization makes predictions of a variable on a yearly scale although the variable is actually observed at shorter time intervals. Given such a yearly prediction, the question will arise as to under which conditions one can say that the actual development of the variable at shorter time intervals deviates so much from the year estimate as to render the latter implausible. Policy makers confronted with such a problem tend to use rather primitive statistical methods of inference. In this paper the situation is judged from a statistical point of view and placed in the context of the ‘significance test’ approach to control chart theory. It is assumed that the variables are generated by a multivariate autoregressive moving average model. Thus we derive an approximate distribution of the future observations of the series given the values of some linear compounds of the variables. With this, three control charts can be constructed. The approach is illustrated by an example based on the monthly tax returns of the Dutch central government. The example suggests the usefulness of the approach in many practical situations of forecasting and planning.     

Some observations on bipolar filaments formed by non-muscle myosins.

Adrenal medullary and retinal myosins formed bipolar filaments in vitro. These filaments showed features suggesting flexibility in the rod region of the myosin molecules composing such filaments; in certain cases the myosin heads spread away from the filament backbone, in others the backbone itself was twisted. In addition the bare central backbone showed transverse striations.