Respiratory components in acidophilic bacteria that respire on iron

Abstract

Microorganisms capable of aerobic respiration on ferrous ions are spread throughout eubacterial and archaebacterial phyla. Phylogenetically distinct organisms were shown to express spectrally distinct redox‐active biomolecules during autotrophic growth on soluble iron. A new iron‐oxidizing eubacterium, designated as strain Funis, was investigated. Strain Funis was judged to be different from other known iron‐oxidizing bacteria on the bases of comparative lipid analyses, 16S rRNA sequence analyses, and cytochrome composition studies. When grown autotrophically on ferrous ions, Funis produced conspicuous levels of a novel acid‐stable, acid‐soluble yellow cytochrome with a distinctive absorbance peak at 579 nm in the reduced state.

Stopped‐flow spectrophotometric kinetic studies were conducted on respiratory chain components isolated from cell‐free extracts of Thiobacillus ferrooxidans. Experimental results were consistent with a model where the primary oxidant of ferrous ions is a highly aggregated c‐type cytochrome that then reduces the periplasmic rusticyanin. The Fe(II)‐dependent, cytochrome c‐catalyzed reduction of the rusticyanin possessed three kinetic properties in common with corresponding intact cells that respire on iron: the same anion specificity, a similar dependence of the rate on the concentration of ferrous ions, and similar rates at saturating concentrations of ferrous ions     

Fluorometric, Chromatographic, and Spectronic Evidence for the Non-indolic Nature of Citrus Auxin

Evidence for the non-indolic nature of the new citrus auxinis presented on the basis of fluorometric properties, thin-layerchromatography, Ehrlich's colour reaction, paper electrophoresis,and the infra-red spectra determinations. Citrus auxin had alower Rf in TLC than IAA, did not give the typical indole reactionwith Ehrlich's reagent, and behaved differently in electrophoresis.The infra-red spectra also provided preliminary informationconcerning chemical structure. The hypothesis that indolic compoundsconstitute the only natural auxins in higher plants should berevised in view of this evidence that a non-indole auxin existsin higher plants.     

Alloreactivity of an OVA-specific T-cell clone

A T-cell clone (Lyl-03) derived from BALB/cBy mice, though highly specific for OVA/A^d, reacted to allogeneic spleen cells of 6 of 12 H-2 haplotypes tested. The reactivity to each particular H-2 haplotype required the expression of a non-major histocompatibility complex (MHC) gene product present on the B cells of certain strains of mice. All the alloreactive responses were MHC restricted and were inhibited by class II-specific and L3T4-specific monoclonal antibodies. The non-MHC gene product, X, is a new lymphocyte-stimulating determinant that is not expressed in mice with the xid defect. We favor a model that proposes two independent sites (or receptors) for X and the class II molecule. Contrary to previous models for alloreactivity, the anti-MHC site is not directed to a polymorphic receptor for self-class II epitope on the foreign class II molecule, but rather to a conserved determinant present on both self- and allo-class II molecules. If there is only one antigen receptor on the T-cell clone Lyl-03, then anti-X receptor must bind to a cross-reactive determinant found on immunogenic OVA and the non-MHC coded gene product expressed on the cell surface membrane. We further postulate that class II plus X recognition may be a general rule for alloreactive as well as autoreactive responses. Thus, both allo-class II and allo-class I reactive T cells are similar in that both bind a non-MHC coded gene product prior to activation.Abbreviations used in this paper: APC antigen-presenting cell(s) - Con A concanavalin A - Cl. clone - DME Dulbecco's modified Eagle's medium - FCS fetal calf serum - H-2 histocompatibility-2 - MHC major histocompatibility complex - MLR mixed lymphocyte response - Mls mixed lymphocyte stimulating - OVA chicken ovalbumin - X unknown cell-surface antigen - xid immunodeficiency mapped to the X chromosome     

Major histocompatibility (B) complex and sex effects on the phytohaemagglutinin wattle response

The influence of the major histocompatibility (B) complex and sex on the phytohaemagglutinin (PHA) wattle response was studied in 136 segregants (B2/B2, B2/B5 and B5/B5) of a fourth generation cross between inbred lines 6(1) and 15(1). At 6 weeks of age, chickens were injected with 100 micrograms purified PHA-P. Wattle thickness measurements were taken 4, 24, 48, 72 and 96 h after injection. Analysis of variance showed that 4 h after injection, males had a significantly higher response than females but the sex-genotype interaction was also significant. Females had higher responses than males 24 and 48 h after injection as a consequence of more rapid development and earlier resolution of the reaction in males. B2/B2 chickens had significantly lower responses than B5/B5 chickens 72 and 96 h after injection, signifying a faster late resolution phase in the B2/B2 genotype. The developmental and early resolution phases of the PHA wattle response were influenced by sex while the late resolution phase was influenced by B genotype.     

An electrophoretic karyotype for Schizosaccharomyces pombe by pulsed field gel electrophoresis.

The three chromosomal DNAs of S. pombe have been fractionated by pulsed field gel electrophoresis. The resulting molecular karyotype will greatly speed gene mapping in this organism, and it indicates that the separation range of the technique extends to DNA molecules as large as 9,000,000 base pairs.     

Allometric Root/Shoot Relationships and Predicted Water Uptake for Desert Succulents

Root morphology, shoot morphology, and water uptake for Agavedeserti and Ferocactus acanthodes of various sizes were studiedusing allometric relationships (y = ax^b) and a previously developedwater uptake model. Shoot surface area increased with shootvolume with an exponent b of 0.75 for both species. Root lengthand the ground area explored by the roots increased with shootsurface area with b's of 0.72 for A. deserti and 0.92 for F.acanthodes. Various sized individuals had about the same ratioof root length to explored ground area, with higher values occurringfor A. deserti. Predicted water uptake averaged over the exploredground area was approximately constant over a 10⁴-fold rangein shoot surface area, suggesting that shoot size confers nointraspecific competitive advantage for water uptake. For theroot lengths per explored ground area observed in the field,water uptake was predicted to be 85 per cent of maximal; wateruptake could be increased by the production of more rain roots.When differences in shoot volume were accounted for by allometry,small plants had relatively less shoot surface area and relativelymore root length per shoot volume than did large plants, whichmay be important for the water relations of seedling establishment. Agave deserti, Ferocactus acanthodes, allometry, desert succulents, root distribution, root length, seedling growth, seedling establishment, shoot surface area, shoot volume, water uptake     

Nucleosome assembly of simian virus 40 DNA in a mammalian cell extract.

We report here a mammalian cell-free system that can support chromatin assembly. Effective nucleosome assembly in HeLa cell extracts occurred at 125 to 200 mM KCl or potassium glutamate. At this physiological K+ ion concentration, two types of chromatin assembly were observed. The first was interfered with by Mg2+. Other cations such as Mn2+, Ca2+, Fe3+, and spermidine also inhibited this type of nucleosome assembly. The second type of assembly occurred in the presence of Mg2+ and at least equimolar ATP. However, even in the presence of ATP, excess Mg2+ inhibited assembly and promoted catenation of DNA; these effects could be circumvented by excess ATP, GTP, EDTA, or polyglutamic acid. The critical DNA concentration for optimum assembly in both pathways suggested a stoichiometric association of histones with DNA. The spacing of nucleosomes formed by both types of assembly on linear and circular DNA was reasonably regular, but chromatin assembled in the presence of ATP and Mg2+ was more stable.     

Mapping of a gene determining tuberous sclerosis to human chromosome 11q14-11q23

Tuberous sclerosis (TSC) is a dominantly inherited disorder characterized by hamartomas and hamartias in one or more organs, most often in skin, brain, and kidneys. Analysis of the basic genetic defect in tuberous sclerosis would be greatly expedited by definitive determination of the chromosomal location of the TSC gene or genes. We have carried out genetic linkage studies in 15 TSC families, using 34 polymorphic markers including protein markers and DNA markers. Pairwise lod scores were calculated using LIPED, and multipoint analyses were carried out using MENDEL. In the pairwise linkage analysis, using a penetrance value of 90%, a significant positive lod score was obtained with MCT128.1 (D11S144), 11q22-11q23, Zmax 3.26 at theta = 0.08. The tyrosinase probe TYR (11q14-11q22) gave a maximum lod score of 2.88 at theta = 0. In the multipoint analyses the most likely order is (TYR,TSC)-MCT128.1-HHH172. Homogeneity analysis was carried out using the USERM9 subprogram of MENDEL, which conducts the admixture test of C. Smith (1963, Ann. Hum. Genet. 27: 175-182). This test provided no evidence for genetic heterogeneity (that is, non-11-linked families) in this data set.