Allelic variants of Ly-5 in inbred and natural populations of mice

Allelic variants of Ly-5 in inbred commensal and other natural populations of mice were analyzed by patterns of restriction fragment length polymorphisms (RFLP) and Southern hybridization using an Ly-5 cDNA probe and by cell-surface staining with a panel of antibodies directed against polymorphic and nonpolymorphic Ly-5 determinants. New Ly-5 alleles were defined by RFLPs generated by both Eco RI and Bam HI restriction enzyme digests. The Mus musculus subspecies and other species within the genus Mus showed a strong correlation between allelic variants defined by restriction enzymes and serologic specificities. The data also suggest the conservation of the Ly-5 gene throughout the genus Mus.     

Effects of non-MHC loci on resistance to retrovirus-induced immunodeficiency in mice

Mice of certain strains are highly sensitive to development of a severe immunodeficiency disease following inoculation as adults with LP-BM5 murine leukemia viruses (MuLV) whereas others are extremely resistant. These strain-dependent differences in response to infection have been shown to be genetically determined with resistance to disease being, in general, associated with homozygosity for Fv-1 ⁿand H-2 haplotypes a and d and sensitivity with homozygosity for Fv-1 ^band other H-2 haplotypes including b, s, and q. The Fv-1 ^b, H-2 ^rstrain RIIIS/J (RIIIS) was found to be highly resistant to disease even though B10.RIII(71NS)/J (B10.RIII), also H-2 ^r, was very sensitive, thus excluding a role for H-2 in the resistance of RIIIS. The characteristics of RIIIS resistance were evaluated in studies of infected (B10.RIII×RIIIS) F₁, F₂ and reciprocal backcross mice. Resistance to disease was shown to be semidominant and determined by more than one gene, although a preponderant influence of a single gene was suggested. Studies of segregating populations showed that resistance was not associated with or linked to polymorphisms of the V _\complex or genes in proximity to the Emv-2 locus on chromosome 8. However, there was almost complete concordance between absence of disease in infected mice and inhibition of ecotropic virus spread. These results demonstrate that genes other than Fv-1 or H-2 can profoundly influence the development of retrovirus-induced immunodeficiency and replication of ecotropic viruses.Abbreviations MuLV murine leukemia virus - MCF mink cell focus-inducing MuLV - B6 C57BL/6 - BM5d the defective virus in LP-BM5 MuLV - MAIDS murine acquired immunodeficiency syndrome - RIIIS RIIIS/J - B10.RIII B10.RIII (71NS)/J - MLR mixed lymphocyte reaction - FACS fluorescence activated cell sorter     

Specificity and mechanism of influence of amino acid residues on hepatic clearance of oligopeptides

We have investigated the influence of amino acid residues on hepatic clearance of oligopeptides by determining the rate of disappearance (nmol.(min.g liver)-1) of selective oligopeptides from the medium during isolated rat liver perfusion. (a) N terminus: the rate of disappearance of Ala-Leu was greater (p less than 0.01) than those of Gly-Leu, Phe-Leu, and Arg-Leu (208 +/- 13, 135 +/- 13, 116 +/- 12, and 127 +/- 12, respectively). (b) C terminus: the rate of disappearance of Leu-Ala (244 +/- 18) was significantly greater (p less than 0.01) than that of Leu-Gly (145 +/- 16). (c) Number of residues: with each increase in the number of alanine residues (2-4) there was a significant increase in the rate of peptide disappearance, and conversely, with each increase in the number of glycine residues (2-6) there was a significant decrease in the rate of peptide disappearance. Further studies showed no peptide transport by isolated liver plasma membrane vesicles and no significant correlation between the rates of peptide disappearance and hydrolase activities of the perfusion medium but highly significant correlation with hydrolase activity of plasma membrane. We conclude that certain amino acid residues, such as alanine, enhance hepatic clearance of oligopeptides by increasing their affinity as substrates for plasma membrane peptide hydrolases.     

Characterization of Haemophilus parainfluenzae strains with low-Mr or ladder-like lipopolysaccharides

Twenty-five Haemophilus parainfluenzae strains were characterized for lipopolysaccharide (LPS) profiles, outer membrane protein profiles, serum sensitivity, plasmid profiles and DNA homology. Seventeen strains produced low-Mr LPS that did not contain O-sidechains, while the remaining eight strains contained ladder-like LPS suggestive of O-repeated units. This is the first time in the genus Haemophilus that LPS with O-repeated groups has been described. The strains producing the different types of LPS could not be distinguished from each other in outer membrane protein profiles or the other characteristics examined.     

Computed tomography and automated image analysis of prehistoric femora

Non-invasive characterization of limb bone cross-sectional geometry would be useful for biomechanical analyses of skeletal collections. Computed tomography (CT) is potentially the method of choice. Additionally, CT images are suitable for automated analysis. CT is here shown to be both accurate and precise in the analysis of cross-sectional geometry of prehistoric femora. Beam hardening artifacts can be reduced by using a water bath. As the availability of CT for research increases, both bone density and geometry could be determined simultaneously with this method.     

Pregnancy-associated growth factor. II. A T-dependent polyclonal activator of human adult peripheral blood lymphocytes (PBL)

This study examined the ability of pregnancy-associated growth factor (PAGF), a substance found in crude human chorionic gonadotropin (hCG), to induce plaque-forming cells (PFC) in cultured human peripheral blood lymphocytes (PBL). PAGF, 0.25 to 1 mg/ml, induced maximal PFC at 6 to 7 days as measured by the staphylococcal protein A-coupled SRBC reverse hemolytic plaque assay with a rabbit anti-human Ig antiserum. PAGF-induced PFC/culture ranged from 1800 to 39,000 with a mean of 11,524 in unfractionated PBL (N = 24), as compared to 540 to 77,840 with a mean of 17,303 for pokeweed (PWM) (N = 22). Comparison of PAGF- and PWM-induced PFC showed that both induced specific IgG, IgA, and IgM PFC. In most individuals, PAGF induced more IgM and PWM more IgG PFC. The kappa: lambda ratio was 1.5 for unstimulated PBL, and approximately 3.5 for PAGF and PWM. To see if PAGF was a T-dependent polyclonal activator of B cells, T and non-T populations were obtained by SRBC rosettes and negatively selected T4 and T8 cells by complement-mediated lysis of SRBC+(T) cells. Only the recombined subsets which included T4 cells and non-T cells supported PAGF- and PWM-induced PFC. These data indicate that PAGF, a substance derived from commercial extracts of pregnancy urine, is a T4-dependent polyclonal activator of normal human B cells.     

The effects of mispair and nonpair correction in hybrid DNA on base ratios (G + C content) and total amounts of DNA

Base ratios and total DNA amounts can vary substantially between and within higher taxa and genera, and even within species. Gene conversion is one of several mechanisms that could cause such changes. For base substitutions, disparity in conversion direction is accompanied by an equivalent disparity in base ratio at the heterozygous site. Disparity in the direction of gene conversion at meiosis is common and can be extreme. For transitions (which give purine [R]/pyrimidine [Y] mispairs) and for transversions giving unlike R/R and Y/Y mispairs in hybrid DNA, this disparity could give slow but systematic changes in G + C percentage. For transversions giving like R/R and Y/Y mispairs, it could change AT/TA and CG/GC ratios. From the extent of correction direction disparity, one can deduce properties of repair enzymes, such as the ability (1) to excise preferentially the purine from one mispair and the pyrimidine from the other for two different R/Y mispairs from a single heterozygous site and (2) to excise one base preferentially from unlike R/R or Y/Y mispairs. Frame-shifts usually show strong disparity in conversion direction, with preferential cutting of the nonlooped or the looped-out strand of the nonpair in heterozygous h-DNA. The opposite directions of disparity for frame-shifts and their intragenic suppressors as Ascobolus suggest that repair enzymes have a strong, systematic bias as to which strand is cut. The conversion spectra of mutations induced with different mutagens suggest that the nonlooped strand is preferentially cut, so that base additions generally convert to mutant and deletions generally convert to wild-type forms. Especially in nonfunctional or noncoding DNA, this could cause a general increase in DNA amounts. Conversion disparity, selection, mutation, and other processes interact, affecting rates of change in base ratios and total DNA.      

Emergency queen cell production in the honey bee colony

Summary Emergency queen cell production was examined in honey bee colonies of mixed European races. Thirteen colonies were dequeened and followed on a daily basis until after queen emergence. Observations were made on the number of cells, the temporal sequence of queen cell construction, cell location within the nest, the age of larvæ selected for queen rearing, mortality of immature queens and the scenting behavior of workers in queenless colonies.Queen loss was detected within 6–12 hours and was first indicated by an increase in scenting behavior (on colony disturbance) and queen cup construction. The number of scenting workers reached a peak in 12–24 hours and then declined, as queen cell numbers increased. The time of queen cell initiation varied from 12–48 hours in different colonies. Emergency queen cells were usually started over worker larvæ less than 2 days of age (64.7%), but cells were built over 3 (25.3%) and 4 (10.0%) day old larvæ. Only 2 of 268 cells (0.8 %) were started over eggs; one survived and developed into a drone larva. In 6 colonies emergency queen cells were started over drone larvæ but these were destroyed immediately before or shortly after capping. The overall rate for queen cell construction over drone larvæ was 9.3%.The rate at which new queen cells were started after queen loss was high for two to four days, but then declined although new queen cells were started as late as eight or nine days after queen removal. The number of cells produced by a colony usually peaked by the third or fourth day and then leveled. Slight declines in total cell number often occurred because of cell mortality. The number of queen cells started by colonies varied from 11–49 with a mean of 20.4; cell mortality averaged 39.1%. Queen cells were well distributed throughout the brood nest but placement was biased toward the bottom of the frames and away from the entrance.

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Production de cellules royales après orphelinage accidentel dans des colonies d'abeilles à miel

Resume La production de cellules royales après orphelinage accidentel fut examinée dans des colonies d'abeilles de différentes races européennes. Treize colonies ont été quotidiennement placées dans un orphelinat expérimental après l'apparition d'une nouvelle reine. Des observations ont été faites sur le nombre de cellules, le timing de la reconstruction des cellules royales, l'emplacement des cellules à l'intérieur du nid, l'âge des larves sélectionnées en vue de l'élevage des reines, le taux de mortalité des cellules et le phénomène d'exhibition de la glande de Nassanoff des ouvrières dans les colonies orphelines.On a pu détecter la perte d'une reine après 6 à 12 heures; celle-ci fut tout d'abord indiquée par le fait qu'un certain nombre d'abeilles exhibent leur organe odorant lors de l'ouverture de la ruche, et l'élaboration de la cupule royale. Le nombre des ouvrières exposées a atteint son record entre 12 et 24 heures puis s'est mis à décroître, alors que les cellules royales augmentaient. Le temps requis pour l'initiation des cellules royales a varié entre 12 et 48 heures, selon les colonies. Les cellules royales de remplacement ont commencé ordinairement à se former sur des larves d'ouvrières de moins de 2 jours (64,7%), mais des cellules se sont développées sur des larves âgées de 3 (25,3%) à 4 jours (10,0%). Sur 268 cellules, 2 étaient uniquement formées à partir d'ufs, dont un seul survivait et devenait une larve mâle. Dans six des colonies, des cellules royales se sont développées à partir de larves mâles, mais celles-ci furent immédiatement détruites soit avant, soit juste après l'operculation. Le taux de développement de cellules royales était de 9,3% par rapport aux cellules mâles.Le taux de développement de nouvelles cellules royales après la perte d'une reine a été assez élevé pendant une période de 2 à 4 jours, mais s'est mis à décroître bien que de nouvelles cellules royales se formaient entre 8 et 9 jours après le début de l'orphelinage. Nous avons noté un taux record de cellules produites par une colonie vers le 3^e ou 4^e jour, qui s'est ensuite réparti de façon plus égale. Le taux de mortalité des cellules a alors provoqué la baisse du nombre total des cellules. Le nombre des cellules royales des colonies a varié entre 11 et 49, c'est-à-dire une moyenne de 20,4; le taux de mortalité des cellules s'est avéré de 39,1%. Les cellules royales étaient bien distribuées dans tout le nid à couvain, mais surtout vers le fond du cadre, et loin de l'entrée de la ruche.

     

Recombination of human erythrocyte apoprotein and lipid. II. Visualization of apoprotein-lipid bilayer complex by freeze-etching

Bilayers of human erythrocyte apoprotein-lipid complexes were made by dipping a mica plate through monolayers of the complex formed at the air-water interface. Stearic acid and erythrocyte lipid alone served as controls. Freeze-fracture images of the complex at high lipid surface pressures (30 dynes/cm) showed particles (average diameter, 109 Å ± 18 Å) similar to those of erythrocyte ghosts (average diameter, 102 Å ± 19 Å). Control surfaces were smooth. We conclude that part or all of the protein molecule penetrated into the lipid bilayer and that erythrocyte apoprotein-lipid complexes yield fracture faces similar to the native erythrocyte membrane.