Conus-like structure in the eye of the deep-sea teleost Radiicephalus elongatus (Pisces,Teleostei)

Summary A conus-like structure, the hyaloid conus, located on the optic nerve head of the mesopelagic deep-sea teleost Radiicephalus elongatus is described. The hyaloid conus consists of a tapering sheath of unpigmented, vascularized connective tissue enveloping the proximal part of the hyaloid artery which proceeds from the optic nerve head through the vitreous body to the ventrally located falciform process and lens muscles. The hyaloid artery passes through the hyaloid conus without giving off any branches. The conus vessels encircling the hyaloid artery receive arterial blood from the choroid via small arteries and are drained to the choroid by a single vein. The hyaloid conus is compared with the lacertilian conus papillaris. The function of the hyaloid conus is unknown. Because of its small dimensions relative to those of the eyeball and its few capillaries, it is unlikely that the hyaloid conus is a supplemental nutritive device for the retina.     

Hepatic reactions in erythropoietic protoporphyria (author's transl)

The main hepatic change in erythropoietic protoporphyria is the deposition of protoporphyrin. Brown deposits of this pigment occur in bile canaliculi and ductules, discretely in hepatocytes, and secondarily in macrophages and Kupffer cells. The pigment is deposited in a crystalline form. Under the fluorescence microscope with a mercury maximum pressure burner (HO 50) at a wave length of 380--500 nm, it shows a typical red fluorescence even after paraffin embedding. Its crystalline structure results in a characteristic double refraction under the polarising microscope. Light-microscopically, hepatocellular reactions are characterised mainly by discrete alterations in the ergastoplasm. However, cell damage is indicated by diffusely distributed, hyaline single cell necrosis and by cytolytic piecemeal necrosis at the peripheries of hepatic lobules. Numerous, often disturbed mitoses produce binuclear and multinuclear hepatocytes. The obligatory secretion of protoporphyrin into the bile ducts leads to an alteration in the canalicular and ductular excretion apparatus which involves distinct ductular proliferation and accompanying fibrosis. Piecemeal necrosis is a further consequence of this process. The resulting histological picture is similar to sclerosing cholangitis with which it also has in common the slowly progressive development of hepatic cirrhosis.     

Suppression of A-type potassium current in pyramidal neurons of the rat hippocampus, induced by pinacidil and its fluorine derivatives

With the use of a patch-clamp technique in the whole-cell configuration, we studied the effects of pinacidil and its fluorine derivatives on A-type potassium current (I _A) through the membrane of pyramidal neurons of the rat hippocampus. Hydrogen peroxide (10 mM) exerted no influence on the rate of inactivation ofI _A; therefore, this current is probably mediated by Shal Kv4.2 potassium channels. Pinacidil demonstrated the properties of a weakI _A blocker: in the 500 μM concentration it blocked about 45% of the current, while 50 μM of pinacidil fluorine derivatives were capable of blocking up to 30% ofI _A. The effects of pinacidil and its derivatives showed no dependence on the stimulating potential. A similar pattern of the effects of pinacidil fluorine derivatives, which are an order of magnitude stronger than those of pinacidil itself, allows us to suppose that the imine nitrogen of the tested compounds is significantly more involved in the molecular interaction with the site of an A-type potassium channel than the pyridine nitrogen.     

Effect of the lymphocytosis-stimulating factor from Bordetella pertussis on murine lymphoid and hemopoietic cells

Effect of B. pertussis lymphocytosis-promoting factor (LPF) on the lympho-hematopoietic system of mice was studied. The injection of LPF was shown to sharply enhance endogenous colony formation and to induce a severe depletion of thymus cells, reaching its maximum of day 4. Thymocytes obtained on day 2 or 3 after the injection of LPF produced a suppressive effect on endogenous colony formation. The proliferative activity of hematopoietic stem cells sharply increased under the influence of LPF, though it had no radioprotective action. On the following day after the injection of LPF a steep rise in the number of hematopoietic stem cells was observed in the blood of mice: their content increased 20-fold in comparison with the control level. These data may be important for the evaluation of the side effects of pertussis vaccine on the lympho-hematopoietic system.     

Lipid content of terrestrial arthropods in relation to body size,phylogeny, ontogeny and sex

Energy storage in arthropods has important implications for survival and reproduction. The lipid content of 276 species of adult arthropods with wet mass in the range 0.2–6.13 g is determined to assess how lipid mass scales with body mass. The relative contribution of lipids to total body mass is investigated with respect to phylogeny, ontogeny and sex. The lipid content of adult insects, arachnids, and arthropods in general shows an isometric scaling relationship with respect to body mass (M) (M_{arthropod lipid} = ?1.09 ×M_dry^1.01 and M_{arthropod lipid} = ?1.00 ×M_lean^0.98). However, lipid allocation varies between arthropod taxa, as well as with sex and developmental stage within arthropod taxa. Female insects and arachnids generally have higher lipid contents than males, and larval holometabolous insects and juvenile arachnids have higher lipid contents than adults.     

Ethoxyformylation of histidine residues in equine growth hormone

Reactivity of histidine residues in equine growth hormone to ethoxyformic anhydride was studied. The existence of two kinetically different sets was demonstrated: one of them including only the slow reacting histidine 169 (k = 0.164 min-1) and the other containing fast reacting histidines 19 and 21 (k = 0.892 min-1). A correlation between the decrease in the capacity to compete with 125I-labeled hormone for rat liver binding sites and the degree of ethoxyformylation of the fast group was found. Circular dichroism studies indicated no significant conformational changes in the protein with all three residues modified. These results fully agree with those obtained for bovine growth hormone which is further evidence supporting the vinculation of histidines 19 and/or 21 with the binding site of these hormones to their specific receptors.