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.     

Calcium transients in single adrenal chromaffin cells detected with aequorin

The effect of 55 mM K+ and nicotine on intracellular free calcium was monitored in bovine adrenal chromaffin cells microinjected with aequorin. In contrast to results with quin 2, which suggested that stimulation of chromaffin cells resulted in sustained rises in free calcium, aequorin measurements showed that 55 mM K+ and nicotine resulted in a transient (60-90 s) elevation of free calcium. The peak free calcium and duration of the transient elicited by nicotine were dose-dependent. The concentration of nicotine (10 microM) giving a maximal secretory response gave a peak rise in free calcium of up to 1 microM. 55 mM K+ which only releases 30% of the catecholamine released by 10 microM nicotine generated a calcium transient indistinguishable from that due to 10 microM nicotine. These results support the idea that nicotine agonists generate an alternative second messenger in addition to the rise in free calcium.     

Acetylated and detyrosinated alpha-tubulins are co-localized in stable microtubules in rat meningeal fibroblasts

We have examined the distribution of acetylated alpha-tubulin using immunofluorescence microscopy in fibroblastic cells of rat brain meninges. Meningeal fibroblasts showed heterogeneous staining patterns with a monoclonal antibody against acetylated alpha-tubulin ranging from staining of primary cilia or microtubule-organising centers (MTOCs) alone to extensive microtubule networks. Staining with a broad spectrum anti-alpha-tubulin monoclonal indicated that all cells possessed cytoplasmic microtubule networks. From double-labeling experiments using an antibody against acetylated alpha-tubulin (6-11B-1) and antibodies against either tyrosinated or detyrosinated alpha-tubulin, it was found that acetylated alpha-tubulin and tyrosinated alpha-tubulin were often segregated to different microtubules. The microtubules containing acetylated but not tyrosinated alpha-tubulin were cold stable. Therefore, it appeared that in general meningeal cells possessed two subset of microtubules: One subset contained detyrosinated and acetylated alpha-tubulin and was cold stable, and the other contained tyrosinated alpha-tubulin and was cold labile. These results are consistent with the idea that acetylation and detyrosination of alpha-tubulin are involved in the specification of stable microtubules.     

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.     

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     

The macrosatellites of the Toulouse goose: the major tandemly repetitive DNA in the toulouse goose genome

This paper examines the principal classes of repetitive DNA of the Toulouse goose (Anser anser) genome. There are four major classes and they are tandem repeats of less than 200 base pairs (bp). The longest repeat (class A) is 190 bp long and starts with a HinfI site. Class B is 43 bp long, commencing with a FokI site. Classes A and B show no extensive homology to DNA sequences held on a current data base (Genbank) but were confirmed to exist as major repeats in another strain of goose, the Emden goose (Anser anser) genome. Classes C and D are 5-bp repeats of 5' GAGAG 3' and 5' GGGAA 3', respectively. The macrosatellites C and D were compared with a current data base (Genbank) and were found to exist in a variety of other organisms as satellites.     

Tubulin isotypes and their interaction with microtubule associated proteins

Summary To assay the functional significance of the multiple but closely related - and -tubulin polypeptides (termed isotypes) that are expressed in mammalian cells, we have generated a number of sera that uniquely discriminate among these isotypes. These sera have been used to demonstrate that there is no subcellular sorting of either - or -tubulin isotypes among microtubules of diverse function, either in cells growing in culture or in tissues consisting of cell types that contain specialized kinds of microtubule. In spite of this failure to segregate between functionally distinct kinds of microtubule, the fact that isotype-specific amino acid sequences have been strictly conserved over extensive periods of evolutionary time argues persuasively for a functional role for the different tubulin gene products. One possibility is that they are required for specific interactions with microtubule associated proteins (MAPs), and that tubulin isotypes have coevolved with different cell type-specific MAPs with which they must interact. We have tested this hypothesis by examining the distribution of -tubulin isotypes in mammalian cerebellum in relationship to the known patterns of expression of a number of MAPs, and find that these patterns correlate in the case of M 2 and MAP 3, and M 6 and MAP 1 a. These data, plus emerging data based on a structural analysis of tau, MAP 1 b and MAP 2 obtained via sequence determination of cloned cDNAs, are discussed in terms of the possible functional significance of tubulin isotype/MAP interactionsin vivo.     

Gibberellic Acid Sensitivity Determines the Length of the Extension Zone in Wheat Leaves

To test the hypothesis that gibberellic acid (GA) sensitivityaffects the length of the extension zone (LEZ) of leaf No. 1of wheat seedlings, we performed a gene dosage experiment usingRht dwarfing genes that condition GA insensitivity. We utilizednearly isogenic lines, at Rht-dosage levels of 0, 2 and 4 alleles.Anatomical markers (distances between successive stomates) wereused to infer the distribution of growth along the axis of theleaf. Interstomatal distance (ISD) and LEZ were inverse linearfunctions of Rht-dosage. The number of stomates matured perhour was independent of Rht-dosage. The relationship betweenISD and distance along the axis within the extension zone (EZ)was indistinguishable from linear. Rht-dosage did not affectthe slope of the regression of ISD against distance along theEZ. A-REST (AR; ancymidol, a potent GA synthesis inhibitor)reduced LEZ. Wild type was more sensitive to AR than doubledwarf. AR affected growth of leaf No. 1 more than length ofthe coleoptile, regardless of Rht-dosage. AR-dosage affectedcell division, whereas Rht-dosage did not. Extension zone, elongation, gibberellic acid, Rht, wheat, Triticum aesiivum L.