Protonic and cationic changes during cyclical cation transport driven by electron transfer

A method is described for the subcellular fractionation of goldfish xanthophores. The procedure produces relatively pure fractions of caroteniod droplets, pterinosomes, cytosol and what appears to be plasma membrane. The presence of a distinct pattern of proteins is shown to be associated with the carotenoid droplets. Treatment of the xanthophores with ACTH affects the buoyant density of some carotenoid droplets and stimulates the phosphorylation of a polypeptide associated with the carotenoid droplets.     

Molecular heterogeneity of D-end products detected by anti-H-2.28 sera

Immunoprecipitation of NP-40 lysates of 125I-labeled lymph-node cells with different anti-H-2 sera and with anti-Qa-2 serum has shown that the BALB/cByA strain (H-2d, Qa-2-negative) expresses, besides H-2Ld, another molecule that is not detectable in the BALB/c-H-2dm2 strain. Electrophoresis in SDS polyacrylamide gels indicated that this molecule, provisionally designated Lq, has an apparent molecular weight of 41000 daltons, in contrast to approximately 49000 daltons for H-2Kd and H-2Ld, and 47000 daltons for H-2Dd molecules. The anti-Qa-2 serum precipitated from the Qa-2-positive strains BALB/cHeA but not from the Qa-2-negative strains BALB/cByA and BALB/c-H-2dm2 a protein that gave a very strong band corresponding to the molecular weight 41000 daltons in the gel electrophoresis. The biochemical characteristics of the Lq molecule are thus more similar to those of Qa-2 than of H-2 antigens.     

Directional flow of sensillum liquor in blowfly (Phormia regina) labellar chemoreceptors.

Utilizing horseradish peroxidase as a tracer protein, it is shown that trichogen and tormogen cells have a secretory function. Protein tracer from the haemolymph enters these cells by endocytosis and is transported to the sensillum liquor cavity by transport vacuoles and multivesicular bodies. It is also suggested that closely associated pigment cells may be involved in macromolecular transport.     

Chromosomal localization of the met proto-oncogene in the mouse and cat genome

The met proto-oncogene was mapped in the mouse and cat genomes with the use of mouse X hamster and cat X rodent somatic cell hybrid DNA panels. Based on these analyses we assigned the met gene to mouse chromosome 6 and to cat chromosome A2. We also assigned the cat raf-1 proto-oncogene to the A2 chromosome; met and raf-1 are the first cloned DNAs mapped to this linkage group. Using an interspecies backcross we further localized met on mouse chromosome 6 to a position proximal to the beta chain of the T-cell receptor. This places met near the obese locus in a region of mouse chromosome 6 that appears to be homologous with the long arm of human chromosome 7. The close linkage of met to the gene responsible for cystic fibrosis in humans suggests that further genetic analysis of mouse chromosome 6 may be useful in developing a mouse model for the disease.     

Lactic acid bacteria: Micro-organisms able to grow in the absence of available iron and copper

Summary The growth of different species of the genera Lactobacillus, Streptococcus, Pediococcus and Leuconostoc was followed in media in which all available iron and copper was chelated by 2,2-dipyridyl. None of the species tested was inhibited in its growth. Iron and copper complexation, by means of chemical scavengers, could be a useful method to direct non-axenic lactic fermentations.     

A feline class II α gene with striking similarity to the HLA-DPA pseudogene

A genomic library was constructed from DNA of a domestic cat and screened with a human HLA-DR probe at low stringency. Several positive clones were isolated, and the DNA sequence of one of these clones was determined. Comparison with class II gene sequences from other species suggested that the feline gene is a DPA homologue (FLA-DPA) showing 84% similarity with HLA-DP1 in the exon encoding the second domain. The FLA-DPA gene that was isolated is a pseudogene, as two frame-shift mutations are present: one in the exon encoding the second domain, causing premature termination of translation, and one in the exon encoding the transmembrane region. The latter mutation and the further deletion of two codons in the transmembrane exon show a remarkable resemblance to the same exon of the human pseudogene, HLA-DPA2. Hence, both pseudogenes evolved from the same ancestral gene. The inactivation of this DPA gene could therefore have occurred prior to the major mammalian divergence.     

Transduction of host cellular sequences by a retroviral shuttle vector.

We studied the frequencies and types of excision events which can occur with a retroviral shuttle vector containing the simian virus 40 origin of DNA replication. Analysis of the recloned vector plasmids by size and restriction enzyme mapping indicated that most contain one long terminal repeat. By hybridizing the plasmids to a mouse genomic repetitive DNA probe, we also determined that approximately 1 to 3% contain transduced cellular DNA sequences.     

DNA sequence of the coding region of the HLA-B44 gene

An HLA-B44 cDNA clone was identified in a cDNA library constructed from an HLA-B44 homozygous cell line. The DNA sequence was determined and was found to contain the complete coding sequence but for (probably) the three N-terminal codons. Comparisons of the derived amino acid sequence with other HLA-A and -B locus amino acid sequences revealed four HLA-B44-specific substitutions including a new polymorphic site. Regions of strong sequence conservation for HLA-B-locus products were found at the nucleotide and amino acid levels.     

In vitro methylation of specific regions of the cloned Moloney sarcoma virus genome inhibits its transforming activity.

The transforming activity of cloned Moloney sarcoma virus (MSV) proviral DNA was inhibited by in vitro methylation of the DNA at cytosine residues, using HpaII and HhaI methylases before transfection into NIH 3T3 cells. The inhibition of transforming activity due to HpaII methylation was reversed by treatment of the transfected cells with 5-azacytidine, a specific inhibitor of methylation. Analysis of the genomic DNA from the transformed cells which resulted from the transfection of methylated MSV DNA revealed that the integrated MSV proviral DNA was sensitive to HpaII digestion in all cell lines examined, suggesting that loss of methyl groups was necessary for transformation. When cells were infected with Moloney murine leukemia virus at various times after transfection with methylated MSV DNA, the amount of transforming virus produced indicated that the loss of methyl groups occurred within 24 h. Methylation of MSV DNA at HhaI sites was as inhibitory to transforming activity as methylation at HpaII sites. In addition, methylation at both HpaII and HhaI sites did not further reduce the transforming activity of the DNA. These results suggested that; whereas methylation of specific sites on the provirus may not be essential for inhibiting the transforming activity of MSV DNA, methylation of specific regions may be necessary. Thus, by cotransfection of plasmids containing only specific regions of the MSV provirus, it was determined that methylation of the v-mos gene was more inhibitory to transformation than methylation of the viral long terminal repeat.