Analysis and comparison of the mouse and human immunoglobulin heavy chain JH-Cmu-Cdelta locus.

We report here 23,686 bases of contiguous DNA sequences from the mouse germline immunoglobulin heavy chain (H) constant (C) mu delta region. The sequence spans the joining (JH) regions, the mu constant region (C mu), the delta constant region (C delta) coding regions, a domain relic, the mu switch region (S mu), seven blocks of simple sequence repeats, a large unique sequence inverted repeat, a large unique sequence forward repeat, and all of the intervening material. A comparison of this 23.7-kb region with the corresponding human C mu/C delta region reveals clear homology in the coding and introns of C mu but not in the 5' flanking J gene segments nor in the intergenic and C delta regions. This mixed pattern of similarity between the human and the mouse sequences contrasts with high levels of similarity found in the T-cell receptor C alpha/C delta region and alpha and beta myosin genes and the very low levels found in the gamma-crystallin, XRCC1, and beta-globin gene clusters. The human and mouse comparison further suggests the incorporation of novel sequences into expressed genes of IgD.

Stop-transfer regions do not halt translocation of proteins into chloroplasts.

Protein targeting in eukaryotic cells is determined by several topogenic signals. Among these are stop-transfer regions, which halt translocation of proteins across the endoplasmic reticulum membrane. Two different stop-transfer regions were incorporated into precursors for a chloroplast protein, the small subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase. Both chimeric proteins were imported into chloroplasts and did not accumulate in the envelope membranes. Thus, the stop-transfer signals did not function during chloroplast protein import. These observations support the hypothesis that the mechanism for translocation of proteins across the chloroplast envelope is significantly different from that for translocation across the endoplasmic reticulum membrane.

Antiinflammatory effects of free radical scavengers and antioxidants: further support for proinflammatory roles of endogenous hydrogen peroxide and lipid peroxides.

Scavengers of reactive oxygen species were tested by local administration during granulomatous inflammation in the rat, induced by the subdermal implantation of carrageenin-soaked sponges. Drugs were administered either in a single dose immediately after sponge implantation, or in daily doses on days 3-6 of inflammation. The effects of the injected drugs were assessed using the day 7 granuloma. When given at the moment of sponge implantation, catalase showed antiinflammatory effects, whereas superoxide dismutase did not. However, the addition of superoxide dismutase to catalase, prior to injection, markedly potentiated the inhibition of granuloma formation by catalase alone. Negative results obtained with scavengers of hydroxyl radicals and singlet molecular oxygen suggest that protection of superoxide dismutase by catalase from inactivation by hydrogen peroxide, is a likely explanation for the observed potentiation. When administered at the moment of the induction of inflammation, alpha-tocopherol and propyl gallate, both antioxidants, also inhibited granuloma formation. All drugs tested were either ineffective or even enhanced granuloma weight following administration into a preformed granuloma. An inhibitor of both pathways of arachidonate metabolism, phenidone, inhibited granuloma formation irrespective of the moment of administration. The results presented in this paper suggest proinflammatory roles for hydrogen peroxide and lipid peroxides and a possible involvement of hydroxyl radicals and singlet oxygen in the breakdown of collagen.

Depletion of hepatic antioxidants during granulomatous inflammation in the rat and local anti-inflammatory effects of free radical scavengers.

Changes in hepatic oxidative events have been studied during extrahepatic granulomatous inflammation in the rat, together with the local anti-inflammatory effects of scavengers of reactive oxygen species. During remote localized inflammation in the rat, we observed increased hepatic lipid peroxidation and reduced hepatic levels of protecting substances such as ascorbic acid, catalase and reduced glutathione, the specific substrate for the peroxide-metabolizing enzyme, glutathione peroxidase. The levels of superoxide dismutase did not alter significantly during the period of investigation (7 days). The half-life of aminopyrine was longer in rats with a stronger inflammatory response. In addition, catalase and the anti-oxidants, alpha-tocopherol and propyl gallate, inhibited granuloma development on local injection during the acute phase inflammation. Superoxide dismutase alone was devoid of anti-inflammatory effects, but markedly enhanced the effect of catalase. Scavengers of hydroxyl radicals and of singlet oxygen failed to display anti-inflammatory activity. The results indicate that peroxides may act as mediators of inflammation and that increased lipid peroxidation is not limited to the site of inflammation.