The influence of incubation temperature on the rate of human lymphocyte proliferation in vitro

Summary Using the FPG staining technique we have confirmed that incubation temperature has a marked effect on the proliferation rate of cultured lymphocytes. With 48 h-cultures the proportion of 2nd-cycle cells increases linearly over the temperature range 36–39°C. However the absolute size of the increase exhibits interdonor variability.We would like to acknowledge the assistance of the Commission of the European Communities for their provision of a travel grant.     

The loss of tumor-initiating ability inAgrobacterium tumefaciens by incubation at high temperature

Zusammenfassung Durch Inkubation bei hohen Temperaturen (37°C) verliert dasAgrobacterium tumefaciens C-58 allmählich die Fähigkeit zur Gallen- oder Tumorbildung in Pflanzen.     

Epithelial cell swelling during incubation of rat small intestine in vitro

Résumé L'augmentation du fluide du tissu de l'intestin grèle incubé in vitro s'accompagne d'un accroissement du volume des cellules épithéliales.     

Parvalbumin alters mitochondrial dynamics and affects cell morphology

The Ca²⁺-binding protein parvalbumin (PV) and mitochondria play important roles in Ca²⁺ signaling, buffering and sequestration. Antagonistic regulation of PV and mitochondrial volume is observed in in vitro and in vivo model systems. Changes in mitochondrial morphology, mitochondrial volume and dynamics (fusion, fission, mitophagy) resulting from modulation of PV were investigated in MDCK epithelial cells with stable overexpression/downregulation of PV. Increased PV levels resulted in smaller, roundish cells and shorter mitochondria, the latter phenomenon related to reduced fusion rates and decreased expression of genes involved in mitochondrial fusion. PV-overexpressing cells displayed increased mitophagy, a likely cause for the decreased mitochondrial volumes and the smaller overall cell size. Cells showed lower mobility in vitro, paralleled by reduced protrusions. Constitutive PV down-regulation in PV-overexpressing cells reverted mitochondrial morphology and fractional volume to the state present in control MDCK cells, resulting from increased mitochondrial movement and augmented fusion rates. PV-modulated, bi-directional and reversible mitochondrial dynamics are key to regulation of mitochondrial volume.     

Induction of cyst formation by low temperature in the dinoflagellateGonyaulax polyedra Stein: Dependence on circadian phase and requirement of light

Encystment, which at a temperature of 15°C is photoperiodically controlled inGonyaulax polyedra, can also be induced by a decrease of temperature, from 20 to 10 or 8°C in the absence of photoperiodic signals. The cyst-inducing capacity of the decrease in temperature depends on the circadian phase: in constant light, the maximum of sensitivity was found at the beginning of subjective night. In a light/dark cycle, however, cyst formation was reduced during dark phase, indicating that light is required for the process of encystment. A similar light dependence was seen in the effect of the physiologically occurring cyst inducer 5-methoxytryptamine, but not in the encystment response to the protonophores monensin and nigericin.     

Effect of lighting conditions on the porphyrin content and morphology of the Harderian gland and on uterine morphology in the golden hamster

Zusammenfassung Bei Goldhamstern, welche längere Zeit im Dunkelversuch (72 Tage) gehalten wurden, konnten in der Harder'schen Drüse zwei Zellarten nachgewiesen werden, bei konstantem Licht dagegen nur eine einzige Zellart. Der Porphyringehalt in diesen Drüsen ist bedeutend höher.

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Acknowledgement. We would like to thank Dr.Berta Santesson for chromosom alanalysis andAgnetha Johansson for technical assistance. This work was supported by grant from Carl-Bertel Nathhorsts Vetenskapliga och Allmännyttiga Stiftelser, and the Swedish Medical Research Council grant No. B72-21X-3371-02B.     

Dependence of the contractility of coronary muscle on substances favouring contraction and relaxation

Zusammenfassung Es werden die Besonderheiten der am isolierten Koronargefäss von Rind und Pferd nach elektrischer Reizung, Verabreichung von Adrenalin oder Kalium registrierten Mechanogramme beschrieben. Es wird darauf hingewiesen, dass die Kontraktilität der Muskelzellen des Rinderkoronargefässes von zwei Stoffen abhängig ist, wovon der eine die Kontraktion und der andere die Erschlaffung fördert.

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I thank the Schweizerischer Nationalfonds für wissenschaftliche Forschung for help.