Conversion of mammalian cyclic GMP-dependent protein kinase into modulator-dependent protein kinase (type II) in vitro

The spontaneous conversion of mammalian cyclic GMP-dependent protein kinase (G-PK) into modulator-dependent protein kinase (type II) (M-PKII) in the absence of cGMP or histone was observed in vitro. The findings, together with similarity in substrate protein specificity, suggest that M-PKII is the catalytic subunit of mammalian G-PK.     

Effects of thyrotrophic-releasing hormone (TRH) on thermoregulation in the rat

At ambient temperatures (Ta) of both 8 and 22 degrees C, intraventricular administration of TRH (10-80 microgram) produced a dose-dependent hypothermia in rats. The hypothermia was due to both decreased metabolic heat production and cutaneous vasodilatation. In contrast, at 30 degrees C Ta, TRH increased metabolic heat production (due to behavioral excitation) and led to hyperthermia.     

Nucleolus organizer region location and ‘ring’ chromosomes in the bharal

Summary Silver-staining has been used to identify the nucleolus organizer regions (NORs) in the bharal. These show homology with sheep, goat, cattle and aoudad. The association of the NORs on both telomeres of chromosome 3 results in a ring chromosome.     

Giant collagen fibres in the gonopodium of the mosquitofishHeteradria formosa,Agassiz, 1853 (Pisces,Poeciliidae)

Summary The gonopodium of the mosquitofishHeteradria formosa was studied by transmission electron microscopy. In cross-section the gonopodium shows the following structure from the outside inwards: mutilayered epidermis, basal lamina and central supporting tissue, in which vessels and nerves are embedded. At the top of the gonopodium giant collagen fibres are found, which measure up to 150 m in length and 6 m in diameter. These fibres reinforce the gonopodium.This research was supported by the Deutsche Forschungsgemeinschaft. Address for reprints: Forschungsgruppe Dermatologie der Universität Heidelberg, Im Neuenheimer Feld 324, D-6900 Heidelberg.     

Hemolymph volume determination in the tomato fruitworm,Heliothis zea

Summary The hemolymph volume ofHeliothis zea larvae was determined by the amaranth dye method and found to vary from 28 to 288 l. It averaged 30.6% of b.wt, a value comparable to that obtained with C¹⁴ inulin. Amaranth became evenly distributed in the hemocoele in 3–5 min.     

Circadian rhythm ofβ-glucuronidase

Summary The circadian rhythm of rat liver-glucuronidase has been studied in animals kept under highly standardized laboratory condition. A clear 24 h rhythm has been observed for this enzyme with a peak activity at 01.00 h and a trough at 13.00 h.The work was carried out in Institut für Anatomie I, Medical School, Hannover (Federal Republic of Germany). Supported by grants from Deutsche Forschungsgemeinschaft, Sonderforschungsbereich 146 and VW Stiftung, Hannover A2 11.2000.     

Opposite effects ofβ-adrenoceptor stimulation and 8-bromo-cyclic AMP on potassium efflux in mammalian heart muscle

Summary -adrenoceptor stimulation by isoprenaline increases the potassium efflux in beating guinea-pig atria. This effect is not mimicked by 8-bromo-cyclic AMP, a cyclic AMP analogue which exerts a positive inotropic effect in this preparation.     

The effect ofβ-adrenergic stimulation and blockade on the efflux of PGE1-like material from the isolated perfused rabbit heart

Summary Prostaglandin (PG) release was measured from the isolated perfused rabbit heart. The effects of -adrenergic stimulation and blockade suggest that PG synthesis is regulated in part by adrenergic mechanisms.