Fetuin: an acute phase protein in cattle

Summary Fetuin is a plasma protein present in high concentrations during fetal development in animals of the order Artiodactyla. Its role is not known. The human homologue of fetuin — ₂HS glycoprotein — has been shown to be a negative acute phase protein in adult plasma. In the present study, the concentration of fetuin was measured in the serum of healthy cattle (Bovis bovis) and in animals with various injuries and inflammatory disorders. The levels were decreased by 30% in pregnancy but increased up to 10-fold in some trauma cases. A significant negative correlation between the concentrations of fetuin and albumin has also been found. Thus, fetuin appears to be a positive acute phase protein in cattle.Abbreviations ₂HS ₂HS glycoprotein - AP acute phase     

Steroid hormones as mediators of neural plasticity

Steroid and thyroid hormone receptors are expressed in the developing brain and persist throughout adult life. They mediate a variety of effects on the brain, ranging from developmental effects of thyroid hormone and the process of sexual differentiation to the cyclic changes during reproductive cycles in adult female animals. This review summarizes data from the author's laboratory on three topics: (1) actions of extradiol and progesterone on the ventromedial nucleus of the hypothalamus in adult female and male rats, showing both the cyclicity and the consequences of brain sexual differentiation; (2) actions of estradiol on the cholinergic neurons of the basal forebrain of the female and male rat, reflecting the plasticity of the adult cholinergic system as well as sex differences which are developmentally programmed; and (3) diverse actions of estrogens, thyroid hormone and glucocorticoids on the morphology of hippocampal neurons. The review concludes by discussing the interactions between "organizational" (i.e. developmental) effects and the "activational" effects of steroids on the mature nervous system in relation to the environmental control of brain gene expression.     

Cytochrome c4 from Pseudomonas aeruginosa

The dihaem cytochrome c₄ from Pseudomonas aeruginosa has been crystallized in space group P6₅22 with cell dimensions $\text{a = b = 62.4}\text{A}\text{?}\text{, c = 174.2}\text{A}\text{?}$, and one molecule per asymmetric unit. Two heavy-atom derivatives, UO₂(NO₃)₂ and K₂Pt(NO₂)₄, which substitute at one and three sites, respectively, have allowed a low-resolution electron density map to be obtained. This shows clearly the two domains of the molecule.     

Pyranine (8-hydroxy-1,3,6-pyrenetrisulfonate) as a probe of internal aqueous hydrogen ion concentration in phospholipid vesicles

The fluorescence intensity (at 510 nm) of the hydrophilic pyrene analogue 8-hydroxy-1,3,6-pyrenetrisulfonate (pyranine) is strongly dependent upon the degree of ionization of the 8-hydroxyl group (pKa = 7.2) and hence upon the medium pH, over the range pH 6--10. Because of its polyanionic character, pyranine does not bind significantly to phospholipid vesicles having a net anionic surface charge. As a result, it is possible to form vesicles in the presence of pyranine which, after removal of external probe by gel filtration, contain pyranine entrapped within the internal aqueous compartment. Once entrapped, pyranine does not readily leak out of the vesicles. Because the fluorescence properties of entrapped pyranine resemble closely the properties of bulk pyranine solution with respect to pH sensitivity, pyranine can be used as a reliable reporter of aqueous pH changes within anionic vesicles. When HCl is rapidly added to a suspension of unilamellar soybean phospholipid (asolectin) vesicles preincubated at alkaline pH, a biphasic decrease in the pH of the vesicle inner aqueous compartment is observed. An initial, very rapid and electrically uncompensated H+ influx (t 1/2 less than 1 s) results in the generation of a transmembrane electric potential opposing further H+ influx. This leads to the development of a much slower (t 1/2 approximately equal to 5 min), valinomycin-sensitive, proton--counterion exchange which continues until the proton concentration gradient is eliminated. Similar results were obtained in asolectin vesicles prepared by detergent dilution, in sonicated egg phosphatidylcholine vesicles, and in multilamellar asolectin liposomes. The rather high permeability of soybean lipid membranes to H+ is surprising in view of the widespread use of these lipids for the reconstitution of membrane proteins which are thought to generate or utilize H+ ion gradients in energy transduction reactions.     

Quantitative initiation of microtubule assembly by chromosomes from Chinese hamster ovary cells

The microtubule nucleating capacity of chromosomes was tested in vitro in lysates of Chinese hamster ovary cells. Colcemid-blocked mitotic cells were lysed with the detergent Triton X-100, incubated with exogenous porcine brain tubulin, attached to electron microscope grids and observed as whole-mounts. Under suitable conditions, greater than 98% of the chromosomes gave rise to microtubules at their kinetochore regions, thus unequivocally demonstrating that chromosomes are competent to initiate specifically microtubule formation. The average number of microtubules that polymerized onto a chromosome was 8 +/- 5, and greater than 36% of the chromosomes had between 10 and 19 microtubules per kinetochore region. We conclude that under the lysis conditions employed, virtually all the chromosomes retain their kinetochores, and that the kinetochores retain a substantial fraction of their microtubule nucleating capacity.     

Antigen-binding cells in the peripheral blood of sockeye salmon, Oncorhynchus nerka Walbaum, induced by immersion or intraperitoneal injectijon of Vibro anguillarum bacterin

We used an immunocytoadherence assay to monitor the response of antigen-binding cells (ABC) in the peripheral blood of sockeye salmon, Oncorhynchus nerka , after immersion in, or intraperitoneal injection of, Vibrio anguillarum LS 1–74 bacterin. Both methods initiated an elevated ABC response in less than one day; this response persisted one week longer in the injected than in the immersed fish.