The amino acid sequences of two alpha chains of hemoglobins from Komodo dragon Varanus komodoensis and phylogenetic relationships of amniotes

To elucidate phylogenetic relationships among amniotes and the evolution of alpha globins, hemoglobins were analyzed from the Komodo dragon (Komodo monitor lizard) Varanus komodoensis, the world's largest extant lizard, inhabiting Komodo Islands, Indonesia. Four unique globin chains (alpha A, alpha D, beta B, and beta C) were isolated in an equal molar ratio by high performance liquid chromatography from the hemolysate. The amino acid sequences of two alpha chains were determined. The alpha D chain has a glutamine at E7 as does an alpha chain of a snake, Liophis miliaris, but the alpha A chain has a histidine at E7 like the majority of hemoglobins. Phylogenetic analyses of 19 globins including two alpha chains of Komodo dragon and ones from representative amniotes showed the following results: (1) The a chains of squamates (snakes and lizards), which have a glutamine at E7, are clustered with the embryonic alpha globin family, which typically includes the alpha D chain from birds; (2) birds form a sister group with other reptiles but not with mammals; (3) the genes for embryonic and adult types of alpha globins were possibly produced by duplication of the ancestral alpha gene before ancestral amniotes diverged, indicating that each of the present amniotes might carry descendants of the two types of alpha globin genes; (4) squamates first split off from the ancestor of other reptiles and birds.      

ANTIPYRETIC ACTION OF DEXAMETHASONE ON EGTAZIC ACIDINDUCED FEVER IN RABBITS

本文用脑室灌注和Ｆｕｒａ２测定细胞内游离钙技术观察了地塞米松（ｄｅｘａｍｅｔｈａｓｏｎｅ,ＤＥＸ）对家兔乙二醇双（２氨基乙醚）四乙酸性发热效应和下丘脑细胞内游离钙浓度（［Ｃａ２＋］ｉ）的影响,借此深入探讨地塞米松解热作用的中枢机制。结果发现：脑室灌注乙二醇双（２氨基乙醚）四乙酸（０６ｎｍｏｌ）引起家兔结肠温度明显升高,静脉注射地塞米松（５ｍｇ／ｋｇ）显著抑制家兔乙二醇双（２氨基乙醚）四乙酸性发热,地塞米松（６０～１２０μｍｏｌ／Ｌ）并不影响下丘脑细胞内［Ｃａ２＋］ｉ,而事先脑室灌注抑制基因转录的放线菌素Ｄ（３ｎｍｏｌ）则完全取消了地塞米松对乙二醇双（２氨基乙醚）四乙酸性发热的解热作用。这些结果提示：地塞米松显著抑制家兔乙二醇双（２氨基乙醚）四乙酸性发热,其机制与地塞米松激活脑内某些基因的表达有关,而与下丘脑神经细胞跨膜钙离子流无关。     

The effect of glucose on cellobiose uptake and β-D-glucosidase activity inStreptomyces granaticolor

Glucose inhibits the inducible synthesis of β-D-glucosidase inStreptomyces granaticolor. Neither cAMP nor cGMP influence the inhibitory effect of glucose. Glucose also inhibits the inducible synthesis of the cellobiose uptake system but has no effect on its activity. This may be the mechanism underlying glucose inhibition of induction of β-D-glucosidase inS.granaticolor.     

Virus-induced permeability transition in mitochondria

Isolated rat liver mitochondria undergo permeability transition after supplementation with a suspension of tobacco mosaic virus. Four mitochondrial parameters proved the opening of the permeability transition pore in the inner mitochondrial membrane: increased oxygen consumption, collapse of the membrane potential, release of calcium ions from mitochondria, and high amplitude mitochondrial swelling. All virus-induced changes in mitochondria were prevented by cyclosporin A. These effects were not observed if the virus was treated with EGTA or disrupted by heating. Protein component of the virus particle in the form of 20S aggregate A-protein, or helical polymer, as well as supernatant of the heat-disrupted virus sample, had no effect on mitochondrial functioning. Electron microscopy revealed the direct interaction of the virus particles with isolated mitochondria. The possible role of the mitochondrial permeability transition pore in virus-induced apoptosis is discussed.     

Comparative structural stability of subunits of the potato virus X coat protein in solution and in virus particles

Several optical methods and differential scanning calorimetry were used to study the structure and stability of free coat protein (CP) molecules and CP molecules in the virion of the potato virus X (PVX), a filamentous plant virus. All criteria suggest that PVX CP (hereinafter, CP) subunits in solution at room temperature display a certain preserved tertiary structure; however, this structure is very unstable and already denatures at 35°C. Very low concentrations of sodium dodecylsulfate or cetyltrimethylammonium bromide also disrupt the CP tertiary structure, three-five molecules of these detergents per one protein molecule being sufficient. However, the secondary structure of CP molecules does not change under the same conditions. Once included into the virion, CP subunits become considerably more stable towards increased temperature and detergents. This combination of a highly labile tertiary structure and a fairly stable secondary structure of free CP can be a structural basis for the recently discovered ability of PVX CP to assume two distinct functional states within the virion.     

Catabolite repression of different inducible enzymes inEscherichia coli and the effect of cAMP

Simultaneous induction of two enzymes sensitive to catabolite repression does not lead to an additive decrease of the specific activity of the two. Exogenously added cAMP increases the specific activity of catabolically repressed enzymes, irrespective of whether the enzyme is induced separately or simultaneously with another enzyme. In the presence of 12 different substrates metabolized by inducible enzymes glucose does not bring about catabolite repression. Synthesis of cAMP is identical with that occurring under conditions when glucose brings about catabolite repression.     

Immunolocalization of MMP-19 in the human intervertebral disc: implications for disc aging and degeneration

Matrix metalloproteinases (MMPs) degrade components of the extracellular matrix of the disc, but the presence of MMP-19 has not been explored. In other tissues, MMP-19 is known to act in proteolysis of the insulin-like growth factor (IGF) binding protein-3, thereby exposing this protein to make it available to influence cell behavior. MMP-19 also has been shown to inhibit capillary-like formation and thus play a role in the avascular nature of the disc. Using immunohistochemistry, normal discs from six subjects aged newborn through 10 years and 20 disc specimens from control donors or surgical patients aged 15-76 (mean age 40.2 years) were examined for immunolocalization of MMP-19; six Thompson grade I discs, five Thompson grade II, eight Thompson grade III, five Thompson grade IV, and one Thompson grade V discs were analyzed. The results indicate that in discs from young subjects, MMP-19 was uniformly localized in the outer annulus. In discs from adult donors and surgical patients, outer and inner annulus cells only occasionally showed MMP-19 localization. The greatest expression of MMP-19 was observed in young discs, and little expression was seen in older or degenerating discs. Because MMP-19 has been shown to regulate IGF-mediated proliferation in other tissues, its decline in the aging/degenerating disc may contribute to the age-related decrease in disc cell numbers.