Anaerobic growth on elemental sulfur using dissimilar iron reduction by autotrophic Thiobacillus ferrooxidans

Abstract Anaerobic growth on elemental sulfur using dissimilar iron reduction by Thiobacillus ferrooxidans has been demonstrated. The ferric ion reducing activity (FIR) of the anaerobic cells was double that of the aerobic cells. Significant differences in inhibition of FIR by respiratory inhibitors were observed between aerobic and anaerobic cells. A higher amount of cytochrome was detected in anaerobic cells compared to aerobic cells. Absorption minima developed with the addition of ferric sulfate in the dithionite reduced cell suspension demonstrated that the ferric ion could accept electrons from the cytochrome system of this bacterium. The possibility of two different electron transport chains in ferric ion reduction is discussed.     

Genetic transformation of Medicago truncatula using Agrobacterium with genetically modified Ri and disarmed Ti plasmids

Summary Fertile transgenic plants of the annual pasture legume Medicago truncatula were obtained by Agrobacterium-mediated transformation, utilising a disarmed Ti plasmid and a binary vector containing the kanamycin resistance gene under the control of the cauliflower mosaic virus 35S promoter. Factors contributing to the result included an improved plant regeneration protocol and the use of explants from a plant identified as possessing high regeneration capability from tissue culture. Genes present on the T-DNA of the Ri plasmid had a negative effect on somatic embryogenesis. Only tissue inoculated with Agrobacterium strains containing a disarmed Ti plasmid lacking the T-DNA region or a Ri plasmid with an inactivated rol A gene regenerated transgenic plants. Fertile transgenic plants were only obtained with disarmed A. tumefaciens, and the introduced NPT II gene was transmitted to R₁ progeny.Abbreviations BAP 6-benzylaminopurine - NAA 1-naphthaleneacetic acid - NPT neomycin phosphotransferase     

The effects of extracellular matrix (ECM) proteins on the attachment of Pneumocystis carinii to lung cell lines in vitro.

Pneumocystis carinii cells labeled with fluorescein isothiocyanate were co-cultured with tissue culture cells. Measurements of attachment was determined by the tissue culture cell fluorescence after washing out the P. carinii organisms. The effects of the extracellular matrix proteins, laminin and fibronectin, on the binding of P. carinii onto the monolayer of cultured cells were investigated for better understanding of organism-cell interactions. The internalization of P. carinii by MRC5 cells was observed.     

Poliovirus antigen chimeras.

Poliovirus, the aetiological agent of paralytic poliomyelitis, is arguably the best characterized of all animal viruses. Using recombinant-DNA technology, this information, together with the availability of infectious cDNA clones of the notably safe and efficacious live attenuated Sabin 1 vaccine strains of poliovirus, has enabled the creation of hybrid viruses (chimeras) possessing novel antigenicity. The potential applications of these 'epitope-presentation systems' include their use as immunogens, as antigens for serodiagnosis, and as vaccines.     

Identification of a matrix-associated region 5'' of an immunoglobulin heavy chain variable region gene.

In the accompanying report (C. F. Webb, C. Das, S. Eaton, K. Calame, and P. Tucker, Mol. Cell. Biol. 11:5197-5205, 1991), we characterize B-cell-specific protein-DNA interactions at -500 and -200 bp upstream of the mu immunoglobulin heavy chain promoter whose abundances were increased by interleukin-5 plus antigen. Because of the high A + T/G + C ratio of these sequences and the consistent findings by others that enhancer- and promoterlike regions are often located near matrix-associated regions, we asked whether these sequences might also be involved in binding to the nuclear matrix. Indeed, DNA fragments containing the -500 binding site were bound by nuclear matrix proteins. Furthermore, UV cross-linking studies showed that the DNA binding site for interleukin-5-plus-antigen-inducible proteins could also bind to proteins solubilized from the nuclear matrix. Nuclear matrix-associated sequences have also been demonstrated on either side of the intronic immunoglobulin heavy chain enhancer. Our data suggest a topological model by which interactions among proteins bound to the promoter and distal enhancer sequences might occur.     

Study of properties of cholinephosphotransferase from fetal guinea pig lung mitochondria and microsomes

Summary We have reported earlier that cholinephosphotransferase (EC 2.7.8.2) is present in both mitochondria and microsomes of fetal guinea pig lung. This study was designed to compare the properties of mitochondrial and microsomal cholinephosphotransferase in fetal guinea pig lung. Various parameters, such as substrate specificity, K_m values, sensitivity to N-ethylmaleimide, dithiothreitol and trypsin were measured. Both showed significant preference for unsaturated diacylglycerols over saturated diacylglycerols. Data on K_m and V_max indicate that the affinity of this enzyme for different diacylglycerols varies between the two forms. The ID₅₀ values for N-ethylmaleimide were 20 mM and 12.5 mM for the mitochondrial and microsomal form of the enzyme, respectively. Dithiothreitol showed an inhibitory effect on both; however, the mitochondrial form was inhibited less than the microsomal form. The effects of N-ethylmaleimide and dithiothreitol on both forms of enzyme indicated that the microsomal cholinephosphotransferase requires a higher concentration of -SH for its activity than the mitochondrial enzyme does. The enzyme was inhibited by trypsin in both mitochondria and microsome under isotonic condition suggesting that this enzyme is on the outside of the membrane in both endoplasmic reticulum and mitochondria.     

A new allele of the duplicated 27kD zein locus of maize generated by homologous recombination.

The 27kD zein storage protein locus in many inbred lines of maize consists of a tandem duplication of 12kb, with an expressed gene in each repeat, termed A and B. A single-copy allele with only the A gene can be generated from this duplication in particular stocks of the maize inbred line A188 by a mitotic process that includes a crossover at the 3' regions of the two genes (1). Here, we characterize a second single-copy allele with only the B gene, found in different stocks of A188. This allele arises from a homologous recombination at the highly conserved 5' regions of the two repeats, and cloning and sequencing of this allele define the crossover region. The A and B genes in the duplicated allele were previously shown to be expressed at different levels; this difference remains unchanged in either recombinant allele. Therefore, the crossover points of these two recombinant alleles define the borders of cis-acting sequences responsible for the differential expression of the two genes.     

Discrimination of the sign of frequency differences bySternopygus,an electric fish without a jamming avoidance response

Several species of weakly electric fish reflexively change their frequency of electric organ discharge (EOD) in response to sensing signals of similar frequency from conspecifics; that is, they exhibit jamming avoidance responses (JAR).Eigenmannia increases its EOD frequency if jammed by a signal of lower frequency and decreases its EOD frequency if jammed by a signal of higher frequency. This discrimination is based on an analysis of the patterns of amplitude modulations and phase differences resulting from signal interference. Fish of the closely related genus,Sternopygus, however, do not exhibit a JAR. Here we show that despite lacking this behavior,Sternopygus shares many sensory processing capacities withEigenmannia:

Hemoglobin E distribution in ten endogamous population groups of Assam, India

Previous studies have reported a high incidence of hemoglobin E (HbE) in Northeast Indian populations. In the present study 10 endogamous populations of Assam belonging to two racial groups, Caucasoid and Mongoloid, were examined. The frequency of HbE gene (Hb beta E) in the Caucasoid caste populations is around 0.1, whereas the gene is highly prevalent in the Mongoloid populations, frequencies ranging between 0.2 and 0.6. Predominance of Hb beta E in the Tibeto-Burman speakers is contrary to observations made in Southeast Asia, where an association between Austro-Asiatic speakers and high prevalence of HbE exist. The highest occurrence of the gene in this area, which is on the far end of the proposed centre of distribution in Northern Kampuchea and Northeast Thailand, is also a deviation from the expected pattern of gene distribution. It is speculated that Hb beta E in the Tibeto-Burman populations of Assam arose by an independent mutation which contributed to the high frequencies of Hb beta E in the Northeast Indian populations.     

Anthropological studies in Assam, India. 6. Differentiation processes among Assamese populations

In 1978-79 13 Assamese populations--two Muslim groups, five Mongoloid groups and 6 Hindu caste groups--have been investigated for the distribution of anthropometric, anthroposcopic and dermatoglyphic traits as well as for the distribution of ABO blood groups and PTC taste sensitivity. Except for finger ridge patterns all traits under investigation showed a marked intergroup variability. For anthropometric, anthroposcopic and dermatoglyphic traits a clear differentiation in Mongoloid populations on one hand and Hindu caste groups on the other could be observed and be substantiated by results of corresponding distance analyses. With regard to Muslims it has to be distinguished between Marias who seem to be more closely related to Mongoloid populations and Sheikhs whose phenotypic appearance is more like that of the Hindu caste groups. The results are discussed.