Lithium exchange in from epithelium: determination of unidirectional flux using the stable isotopes 6Li and 7Li in an ionic analyzer]

The use of the stable isotopes 6 and 7 of lithium, and detection with the ionic analyser, allow the measurement of unidirectional transepithelial Li-fluxes, between "external" and "internal" solutions which both contain 80% Na and 20% Li. Efflux was found to be bigger than influx. An important lag-phase on the curve, reveals the interference of a Li-compartment, with a high capacity, in the epithelium itself.     

Changes in ecdysone levels in the spiderPisaura mirabilis nymphs (Araneae,Pisauridae)

Summary RIA of ecdysones are made on nymphal extracts ofPisaura mirabilis during the intermoulting cycle. The hormone level is low during exuviation and the greatest part of the intermoulting period but increases notably before and after ecdysis. The main hormonal peak or pre-ecdysial peak is due to -ecdysone, characterized by combined TLC/RIA.Acknowledgment. We wish to thank Dr M. Hirn for his help during the manipulations and J. Britton who has translated the text into English.     

A cannabinoid with cardiovascular activity but no overt behavioral effects

Summary Abnormal-⁸-tetrahydrocannabidiol (ABN-⁸-THC) failed to elicit central nervous system and cardiovascular effects in laboratory animals. Abnormal-cannabidiol (ABN-CBD) was also devoid of overt behavioral effects but produced marked hypotension with only slight bradycardia in anesthesized dogs.Acknowledgment. This work was supported by NIDA (grant No. DA-00574-01 and DA-00490) and Virginia Heart Society (grant No. RR-05697)     

A physicochemical mechanism for magnetic field detection by migratory birds and homing pigeons

Migratory birds and homing pigeons can apparently obtain directional information from the Earth's magnetic field. The effect is difficult to detect, and discussion of the possible process of magnetic field detection by birds seems so far to have foundered on the simple fact that the orientational effect of the Earth's magnetic field on a single electron spin associated with a molecule of animal tissue would be of the order 10(-8) eV--almost certainly too small to be detectable biologically. Here I direct attention to a process which would overcome this basic problem, and which also seems to provide an explanation of all the main features of published data. It is a mechanism in principle only, however, and is discussed here in no more detail than is necessary to clarify the basic ideas and to provide a basis for further investigation.     

Economics of alternative energy sources

An important part of the oil and natural gas at present consumed in the UK is used for the heating of buildings, a demand which shows large diurnal, day-to-day and annual fluctuations. The replacement of this energy by nuclear-generated electricity, as at present envisaged, would require the construction of some 250 GW of additional capacity by the end of the century, a progamme which does not seem feasible. By incorporating relatively cheap, short term storage in the form of low-grade heat, the generating capacity required to fulfil peak demand could be reduced by more than 50%. As soon as such storage is provided, however, other sources of energy become viable and attractive alternatives, and the UK is well situated to make use of wind, wave, and tidal power. It seems likely that the value of North Sea oil/gas reserves as feedstock to the chemical industry will rise sufficiently to make an early reduction in their consumption as fuel of great economic importance.     

Determinant selection is a macrophage dependent immune response gene function

Immune response (Ir) genes are linked to the species histocompatibility complex and define as yet uncharacterised phenotypic products which control the immune response to thymus dependent antigens. Antibody formation and antigen induced T lymphocyte proliferation are two examples of immune phenomena which, in vivo and in vitro, operate under Ir gene influence. To clarify their mechanism of action and cellular location, we have examined the contribution of antigen structure (amino acid sequence and conformation to Ir gene control of antigen recognition by T lymphocytes) as well as to the critical role played by the antigen presenting macrophage in expression of that control. We report that immune response gene control of antigen recognition operates at least in part at the level of the macrophage.