Sequence variation at the major histocompatibility complex locus DQ beta in beluga whales (Delphinapterus leucas) [published erratum appears in Mol Biol Evol 1995 Nov;12(6):1174]

Genetic variation at the Major Histocompatibility Complex locus DQ beta was analyzed in 233 beluga whales (Delphinapterus leucas) from seven populations: St. Lawrence Estuary, eastern Beaufort Sea, eastern Chukchi Sea, western Hudson Bay, eastern Hudson Bay, southeastern Baffin Island, and High Arctic and in 12 narwhals (Monodon monoceros) sympatric with the High Arctic beluga population. Variation was assessed by amplification of the exon coding for the peptide binding region via the polymerase chain reaction, followed by either cloning and DNA sequencing or single-stranded conformation polymorphism analysis. Five alleles were found across the beluga populations and one in the narwhal. Pairwise comparisons of these alleles showed a 5:1 ratio of nonsynonymous to synonymous substitutions per site leading to eight amino acid differences, five of which were nonconservative substitutions, centered around positions previously shown to be important for peptide binding. Although the amount of allelic variation is low when compared with terrestrial mammals, the nature of the substitutions in the peptide binding sites indicates an important role for the DQ beta locus in the cellular immune response of beluga whales. Comparisons of allele frequencies among populations show the High Arctic population to be different (P < or = .005) from the other beluga populations surveyed. In these other populations an allele, Dele-DQ beta*0101-2, was found in 98% of the animals, while in the High Arctic it was found in only 52% of the animals. Two other alleles were found at high frequencies in the High Arctic population, one being very similar to the single allele found in narwhal.      

A new 2'-hydroxyl protecting group for the automated synthesis of oligoribonucleotides.

We have developed a new type of 2'-hydroxyl protecting group for the automated machine synthesis of RNA oligomers: a 2-hydroxyisophthalate formaldehyde acetal (HIFA). The unique feature of this protecting group is that, as the bis ester, it is relatively stable to the acidic conditions that are used for repeated removal of dimethoxytrityl groups during chain elongation, but the final deprotection step in alkali, which cleaves the chain from the support and removes the base and phosphate protecting groups, converts it to the bis carboxylate and this can be removed relatively rapidly by treatment with mild acid. Conversion of the bis ester to the bis carboxylic acid increases the rate of acid-catalyzed hydrolysis of the acetal by 42-fold at pH 1, and, possibly, by 1320-fold at pH 3. The bis ester is 112 times more stable than the 1-(2-fluorophenyl)-4-methoxypiperidin-4-yl group (Fpmp) towards hydrolysis at pH 1, while the bis acid is only 2.35 times more stable than Fpmp at pH 3. In synthesis of the dimers UpU and UpG, with a coupling time of 5 min, the dimethoxytrityl cation assay indicated coupling yields of > 98%.     

Isolation and characterization of the rabbit prt gene product

The product of the rabbit prt gene (PRT), a gene linked to the immunoglobulin κ-light chain gene ab, was purified from rabbit serum by precipitation with ammonium sulfate and by chromotography on DEAE-Sephadex and Sephacryl S300. Analysis of PRT indicated that it was associated rabbit hemopexin; the molecular weight of PRT (i.e., 68,000), as estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, was similar to the reported molecular weight of rabbit hemopexin; the PRT phenotypes correlated with the phenotypes of a hematin binding protein; PRT itself bound hematin; and the amino acid composition of PRT was similar to the amino acid composition of rabbit hemopexin. The prt gene, however, need not be the structural gene for hemopexin; it may encode a glycosyl transferase responsible in part for the carbohydrate associated with the protein.     

Traumatic disruption of the fibrous skeleton of the heart, with injury of the tricuspid and mitral valves, aortic annulus, and ventricular septum

In an automobile accident, a young man sustained blunt trauma to the chest that caused injury to the fibrous skeleton of the heart. The mitral and tricuspid valves and their annuli were lacerated, the aortic annulus was separated from the ventricular septum, and the ventricular septum was disrupted; however, with surgical management, the patient survived.     

Linkage between low-density lipoprotein and igk light-chain genes in rabbits

The rabbit geneLpq, which codes for a low-density serum lipoprotein², is linked (34.6 ± 5.3 centimorgans) to the Ig kappa light-chain gene (Ab). There is no evidence thatLpq is linked to another gene,Prt, that was previously found to be linked to theAb gene. This suggests that the gene order for the three genes isPrt- Ab- Lpq. Abbreviations used in this paper Ig immunoglobulin - a the heavy-chain variable-region geneAa - b the kappa light-chain geneAb - q the low-density serum lipoprotein geneLpq     

Immunochemistry of human Lp[a]: characterization of monoclonal antibodies that cross-react strongly with plasminogen.

Forty different monoclonal antibodies were produced from hybridomas that were raised against human Lp[a]. Of these, 14 strongly cross-reacted with plasminogen on ELISA screening assays while 16 clearly did not and 10 were only marginally cross-reactive. We took advantage of the homology between plasminogen and apo[a] to define the epitopes of 8 strongly cross-reacting monoclonal antibodies. We were able to subdivide these into four general categories based upon site competition assays (using both plasminogen and Lp[a]), and their reactivity with elastolytically derived plasminogen fragments. Group A monoclonal antibodies (F1 1E3, F2 3A3) recognized epitopes within the kringle 5 and protease domains (miniplasminogen) of plasminogen. The group B monoclonal antibody (F6 1A3) reacted solely with plasminogen kringle 4-like domains and appeared to recognize a limited number of sites on Lp[a]. Group C monoclonal antibodies (F6 1B5, F6 1G9) recognized a second, more frequently distributed site within these kringle 4-like domains. The final group, D, monoclonal antibodies (F6 2C3, F6 2G2, F6 3F4) reacted with a cluster of sites found associated with kringle 4-like domains but also reacted with the miniplasminogen domain. Interestingly, only the members of this group were able to interfere with the proteolytic activity of plasmin. Neither periodate treatment of Lp[a] nor incubation of Lp[a] with epsilon-aminocaproic acid affected the binding of any of our monoclonal antibodies.