Deactivation of macrophage oxidative burstin vitro by different strains ofHistoplasma capsulatum

It was previously reported thatHistoplasma capsulatum (Hc) yeast not only failed to stimulate a murine macrophage oxidative burst (OB), but they also blunted or abolished OB stimulation by a subsequent encounter with potent stimuli such as zymosan or phorbol 12-myristate 13-acetate (PMA). The present studies show that macrophage deactivation is proportional to the time of incubation and the dose of Hc yeast that induce the deactivated state. Hc yeast derived from a virulent strain (G217B) are more efficient inducers of macrophage deactivation than similar preparations derived from the avirulent Downs Hc strain. Yeast cells of two other pathogenic fungi,Candida albicans andCryptococcus neoformans are shown to stimulate rather than deactivate a macrophage OB.     

Inheritance of migraine investigated by complex segregation analysis

Migraine is the most common neurological disorder, affecting about 20% of adults. The mode of inheritance was analyzed in the two main types of migraine, migraine without aura (MO) and migraine with aura (MA), by complex segregation analysis using the computer program POINTER. We included 126 probands with MO and 127 probands with MA from the general population. Firstdegree relatives and spouses were blindly interviewed by a neurological research fellow. The complex segregation analysis indicated that both MO and MA have multifactorial inheritance without generational difference.     

Utilization of protein profiles for the characterization of halophilic bacteria

Proteins from 24 halophilic bacteria, including Haloarcula marismortui, Haloarcula vallismortis, Haloferax mediteranei, Haloferax gibbonsii, Halobacterium salinarium, as well as unknown isolates from Enid, Oklahoma; Jefferson Island, Louisiana; and the Salado Formation-New Mexico, were analyzed by one-dimensional SDS-polyacrylamide gel electrophoresis (SDS-PAGE). Their protein profiles were compared, and the bacteria were grouped according to the Statistical Analysis System (SAS Institute, Cary, North Carolina) on an IBM 4316 computer. The groupings made from protein profiles showed agreement with groupings made from DNA reassociation data. The various known halophiles were easily separated into the three main halobacterial genera. The data show that one-dimensional SDS-PAGE can be easily used to rapidly screen large numbers of unknown strains to group them into related clusters. This technique offers a way to reduce the total number of halophilic isolates being studied in large taxonomic research programs.     

Molecular and genetic studies on the euchromatin-heterochromatin transition region of the X chromosome of Drosophila melanogaster

A recombinant Charon 4 bacteriophage has been isolated on the basis of RNAs which are enriched in the head of the adult Drosophila melanogaster and hence are likely to be of neural origin. The cloned insert maps to the near vicinity of the uncoordinated locus in polytene chromosome band 19E8. This band is within the transition zone between the euchromatic and heterochromatic regions of the X chromosome, a region which has been well characterized cytogenetically. The insert contains both repetitious and low copy number sequences, some of which vary extensively in both frequency and restriction fragment size between different laboratory strains. One particular family of moderately repeated sequences occurs predominantly in divisions 19 and 20 of the X chromosome and perhaps the distally located X heterochromatin. The molecular landscape surrounding the initial entry point contains many repeated sequences and is thus unlike those observed in most published chromosomal walks. The possible significance of the presence of repeated sequence families in the distinct properties of this region are discussed.     

The detection of picomolar quantities of GD1b,GT1b and GQ1b on thin-layer chromatograms by the direct binding of125I-labeled tetanus toxin,fragment C

The¹²⁵I-labeled fragment C of tetanus toxin was found to bind specifically to the gangliosides G_D1b, G_T1b, and G_Q1b when applied to thin-layer chromatograms on which a mixture of gangliosides had been resolved. As little as 2.5 pmoles of these gangliosides could be detected by this method. In addition to factors determined by the sample, namely the amount and species of gangliosides present, optimal binding of the¹²⁵I-labeled fragment C also depended upon the iodination procedure used to generate the probe, the toxin concentration, and the concentration, buffer type, pH, and ionic strength of the binding solution. This new technique was shown to be a sensitive method for the detection and identification of specific gangliosides originating from extraneural or neural cells.Nomenclature: The gangliosides follow the nomenclature system of Svennerholm [Eur J Biochem (1977) 79:11–21] G_M3 II³NeuAc-LacCer - G_D3 II³(NeuAc)₂-LacCer - G_M1 II³NeuAc-GgOse₄Cer - G_D1a IV³NeuAc, II³NeuAc-GgOse₄Cer - G_D1b II³(NeuAc)₂-GgOse₄Cer - G_T1b IV³NeuAc, II³(NeuAc)²-GgOse₄Cer - G_Q1b IV³(Neu-Ac)₂, II³(NeuAc)₂-GgOse₄Cer - G_P1b IV³(NeuAc)₃, II³(NeuAc)₂-GgOse₄Cer     

Influence of 0.5 ppm nitrogen dioxide exposure of mice on macrophage congregation in the lungs

Summary The lungs of 12 mice, half of which were exposed to continuous 0.5 ppm nitrogen dioxide for 3 weeks, were explanted in culture, and the instances of macrophage congregation were quantitated according to numbers of target cells involved, categories of congregation from three to 11 or more, numbers of macrophages participating in each category for the total cultures, and the influence of delaying explantation for 24 and 96 hr. A total of 9042 macrophages and 2140 epithelial and spindle target cells were counted in the outgrowths from 306 explants. The incidence of macrophage congregation (or numbers of target cells) was greater for the cultures from the NO₂-exposed animals, both with respect to total incidences between groups (p→0), and the 0-hr (p<0.001) and 24-hr (p<0.01) culture subgroups. In addition, the values for T₃ to T₆ macrophage congregation were individually and consistently greater for the exposed animal group. Postmortem interval stress at 96 hr appeared to result in large colonies, but they were reduced greatly in number. Also the incidence of macrophage congregation fell by 28% as compared to 0-hr and 24-hr subgroups. Supported by Grants NHLI No. HL 17412 and EPA No. R. 800881.     

The Influence of the Mating System on the Maintenance of Genetic Variability in Polygenic Characters

The traditional models of the effect of assortative mating and inbreeding on the genetic variance of polygenic characters (Fisher 1918; Wright 1921) presume that there is no natural selection or mutation. In a large population, the genetic variance determined by additive genes may then increase by up to a factor of two with local inbreeding, and even more with assortative mating. The classical models are still used to interpret data from natural populations. But contrary to their assumptions, most metrical characters in natural populations are usually thought to be under a type of selection which depletes polygenic variation. Mutation is then necessary to maintain genetic variation. The present models show that with the additional features of mutation and selection, in a large population, the mating system has no influence on the amount of genetic variability maintained by additive genes.     

Inflammatory cells in solid murine neoplasms. IV. Cytolytic T lymphocytes isolated from regressing or progressing Moloney sarcomas.

Highly purified suspensions of intratumoral T lymphocytes, recovered 11 and 13 days after induction of regressing or progressing Moloney sarcomas, were compared in their ability to lyse specifically the MSC cells used for tumor induction. Cytolytic activity, expressed in terms of lytic units/10(6) T cells, was similar for intratumoral T cell suspensions obtained 11 days after induction of either regressing (3.1 +/- 1.3 LU/10(6) T cells) or progressing (4.3 +/- 1.8) neoplasms. By 13 days post-induction, regressing tumors contained T lymphocytes with an increased cytolytic activity (11.1 +/- 4.5) whereas those from progressing tumors were strikingly less able to kill MSC cells (less than or equal to 0.2). This dramatic loss in cytotoxicity could not be attributed to errors associated with the enzymatic disaggregation method, inhibition by copurified endogenous tumor cells, or immunosuppression induced by viral infection. The changes in functional activity of intratumoral T lymphocytes from the two types of sarcoma appeared to be correlated with the stage of neoplasia. In this model system, cytolytic activity of T lymphocytes increased during spontaneous tumor regression whereas losses in cytotoxicity occurred coincident with the onset of inexorable progression.     

A biochemical mechanism for bacterial chemotaxis

Peritrichous bacteria alternately swim and tumble (thrash about with little forward progress). By selective modulation of tumbling frequency, these bacteria carry out chemotaxis, which is migration to higher concentrations of attractant or lower concentrations of repellent. A model for chemotaxis is presented in which tumbling frequency is regulated by concentration of Ca²⁺ ion at the switch that controls tumbling and swimming. Attractants cause decreased levels of free cytoplasmic Ca²⁺ ion due to binding of Ca²⁺ ion by specific proteins. This Ca²⁺ ion is released when these proteins become methylated. An alternative model. involving a cytoplasmic metabolite “compound X”, is discussed.