The major histocompatibility complex of the rat (Rattus norvegicus)

This review of the RT1 complex, the major histocompatibility complex (MHC) of the rat, focuses on genetic, genomic, evolutionary, and functional aspects at the molecular level. The class I, class II, and framework genes are listed. The physical map of the RT1 complex as revealed by analysis of clonal contigs is compared with the human and mouse MHC, and the degree of orthologous relationship is outlined. Elucidation of the RT1 complex provides important information for using the rat as a model of experimental transplantation and complex diseases.     

The morphological sequence of XY pairing in the Norway rat Rattus norvegicus

The sequence of XY pairing at meiotic prophase in the Norway rat, Rattus norvegicus, has been studied in spread preparations of spermatocytes obtained from pubertal males. As in most mammals, sex chromosome pairing is delayed in relation to that of the autosomes. At one stage in pachytene, the Y is fully paired in synaptonemal complex association with about one-third of the X. Observation in spread preparations at pachytene and diplotene and in air-dried metaphase I preparations indicates that the long arm of the Y pairs with the short arm of the X. Pairing of the Y with both ends of the X is seen in about 4% of pachytene spermatocytes. The possibility that XY pairing in the rat may be nonhomologous (Ashley 1983) is considered, and the view is expressed that the XY synaptonemal complex may be incomplete in fine structural detail, thus not providing for the effective pairing required in true reciprocal recombination. The same mechanism that excludes crossing over from heterochromatic regions of autosomes may also operate to minimize or prevent crossing over in the sex pair of mammals.     

The amino acid sequence of the major parvalbumin of the whiting (Gadus merlangus).

1. The amino acid sequence of the major parvalbumin of the Whiting has been determined; the polypeptide chain is made of 108 residues, the terminal amino acid group is acetylated, there is no disulfide bridges, the structure of the two calcium binding sites is preserved and the distribution along the polypeptide chain of the hydrophobic residues implicated in the compact hydrophobic core of the protein is also maintained. 2. The comparison of this amino acid sequence with other parvalbumins indicates that it belongs to the beta type and that within the Gadidae family two types of parvalbumins also occur.     

Human basement membrane collagen (type IV). The amino acid sequence of the alpha 2(IV) chain and its comparison with the alpha 1(IV) chain reveals deletions in the alpha 1(IV) chain

The cDNA and protein sequences of the N-terminal 60% of the alpha 2(IV) chain of human basement membrane collagen have been determined. By repeated primer extension with synthetic oligodeoxynucleotides and mRNA from either HT1080 cells or human placenta overlapping clones were obtained which cover 3414 bp. The derived protein sequence allows for the first time a comparison and alignment of both alpha chains of type IV collagen from the N terminus. This alignment reveals an additional 43 amino acid residues in the alpha 2(IV) chain as compared to the alpha 1(IV) chain. 21 of these additional residues form a disulfide-bridged loop within the triple helix which is unique among all known collagens.     

Synthesis of thiostatins (major acute-phase alpha 1 proteins) in different strains of Rattus norvegicus

1. Two different thiostatin proteins were detected by crossed immunoelectrophoresis in plasma of the following inbred strains of Rattus norvegicus; Wistar, Sprague Dawley, Hooded Wistar, Lewis, Porton-Albino, ACI, Long Evans, and Katholiek, a mutant strain of the Brown Norway. 2. Only one thiostatin protein was detected using crossed immunoelectrophoresis in plasma from the Buffalo rat. 3. Comparison of partially purified thiostatins from Buffalo, Wistar, and Sprague Dawley rats in polyacrylamide gels showed that the thiostatin protein in Buffalo rat plasma corresponded to thiostatin 1 of the two thiostatins of the Wistar and Sprague Dawley rats. 4. Thiostatin 1 mRNA and thiostatin 2 mRNA, of approximately 1.7 kilobases, were both demonstrated in RNA from Buffalo rat liver.     

Polymorphic microsatellite loci of the rat (Rattus norvegicus)

The EMBL and GenBank DNA databases were searched for microsatellite sequences of the rat containing dinucleotide repeats of (CA)_n and (GA)_n. Among those obtained, 23 sequences were analyzed by polymerase chain reaction to examine the size variation of the amplified fragment in inbred rat strains. All of the 23 microsatellite sequences varied in size among the strains tested. The 23 microsatellite loci in a pair of substrains separated from the same progenitor strain were then analyzed. Fragments identical in size were observed in all loci of the two substrains, indicating the stability of the microsatellite over a large number of generations. The microsatellite loci, therefore, should be useful markers for linkage analyses in the rat.     

The complete amino acid sequence of the major component myoglobin of Amazon river dolphin (Inia geoffrensis).

The complete amino acid sequence of the major component myoglobin from Amazon River dolphin, Inia geoffrensis, was determined by specific cleavage of the protein to obtain large peptides which are readily degraded by the automatic sequencer. Three easily separable peptides were obtained by cleaving the protein with cyanogen bromide at the methionine residues and four peptides were obtained by cleaving the methyl-acetimidated protein with trypsin at the arginine residues. From these peptides over 85% of the sequence was completed. The remainder of the sequence was obtained by fragmentation of the large cyanogen bromide peptide with trypsin. This protein differs from that of the common porpoise, Phocoena phocoena, at seven positions, from that of the common dolphin, Delphinus delphis, at 11 positions, and from that of the sperm whale, Physeter catodon, at 15 positions. By comparison of this sequence with the three-dimensional structure of sperm whale myoglobin it appears that those residues close to the heme group are most conserved followed by those in nonhelical regions and lastly by those in the helical segments. All of the substitutions observed in this sequence fit easily into the three-dimensional structure of the sperm whale myoglobin.     

Skull growth in the albino rat (Rattus norvegicus)

A longitudinal study of growth in the rat skull, based on serial radiographs, has shown that by the age of one month after birth, the braincase attains some 93% of its adult (fifth-month) size whilst the facial skeleton and mandible attain but 75% of their adult size. By the third month, growth in the braincase has virtually ceased, whereas significant facial growth continues until the age of five months.     

Nucleotide sequence variants of Rattus norvegicus mitochondrial DNA

The mitochondrial DNA (mtDNA) molecules of different albino, domesticated rats (Rattus norvegicus) of the SASCO colony are of two kinds (SASCO-1 and SASCO-2) in regard to their sensitivity at certain sites to a number of restriction enzymes. MtDNA molecules from Utah wild R. norvegicus (Wild-UT) have sensitivities to restriction enzymes which differ at some sites from either SASCO-1 or SASCO-2 mtDNA molecules. Four single nucleotide differences were found among the HindIII F fragments (169 nucleotides) of SASCO-1, SASCO-2, and Wild-UT mtDNAs. Arguments are presented in favor of the interpretation that each variant nucleotide is the third nucleotide of the codon containing it, and that none of the four differences would result in a difference in the respective amino acid translated.Dedicated to Professor W. Beermann on the occasion of his 60th birthday     

Idiopathic megaesophagus in a rat (Rattus norvegicus)

Necropsy and histopathologic examination of a rat (Rattus norvegicus) revealed megaesophagus and gangrenous bronchopneumonia. The esophageal dilitation, mural atrophy with persistence of neural structures, regurgitation and bronchopneumonia seen in this case were similar to findings in other animals with megaesophagus.     

Amino acid sequence of the fetal chain of yak haemoglobin

The amino acid sequence of the fetal chain of yak haemoglobin was determined. The sequence is the same as that of the fetal chain of bovine haemoglobin. Phenylalanine is present at position 12 of the helix A in the fetal chain while tryptophan is the amino acid at this position in theβ-chain of yak adult haemoglobin. This amino acid replacement may be responsible for the higher oxygen affinity of yak fetal haemoglobin than yak adult haemoglobin.     

The amino acid sequence of bovine thymus prothymosin alpha

Prothymosin alpha has been purified from calf thymus and its amino acid sequence determined. It contains 109 amino acid residues and closely resembles human prothymosin alpha, with only two substitutions, glutamic acid for aspartic acid at position 31 and alanine for serine at position 83. This is in contrast to six differences between rat and bovine prothymosins, including four substitutions and two deletions. The structural similarity of the bovine and human polypeptides makes the former a good candidate for studies on the evaluation of the biological activities of prothymosin alpha in human systems.     

A partial amino acid sequence for sheep haemoglobin A

Amino acid analysis and terminal-group analysis of tryptic and chymotryptic peptides from sheep haemoglobin A have enabled a partial amino acid sequence to be worked out. By comparing this partial sequence with the known amino acid sequences of human haemoglobins A and F as well as horse slow haemoglobin the most probable sequence of sheep haemoglobin has been deduced.