Comparison of the bacterial HelA protein to the F508 region of the cystic fibrosis transmembrane regulator.

The HelA protein of Rhodobacter capsulatus is the ATP-binding-cassette subunit of an exporter complex required for cytochrome c biogenesis. By primary sequence comparisons the F88 residue of HelA is similar to the F508 residue of the cystic fibrosis transmembrane regulator (CFTR) protein. Previous studies have established that CFTR F508delta or F508R proteins are defective but F508C is functional. Our results demonstrate that the HelA F88 mutants functionally mimic the phenotypes of known CFTR F508 mutants. The phenotypes of additional HelA mutants and the in vivo steady-state levels of these proteins are also reported.     

Zygote implantation to cultured ovules leads to direct embryogenesis and plant regeneration of wheat

Direct embryogenesis and plant regeneration were obtained by implantation of individual wheat ( Triticum aestivum L.) zygotes into cultured ovules of wheat or barley. The zygotes were isolated mechanically from emasculated spikes, 3–9 h after hand-pollination. In 13 independent experiments, a total of 186 zygotes were implanted into excised ovules obtained from emasculated spikes which had been treated previously with 2,4-dichlorophenoxyacetic acid to induce parthenocarpic, embryoless ovary development. On average, 17.2% of the implanted zygotes gave rise to dorsiventrally differentiated embryos. The embryos resembled those growing in planta with no obvious deviation from the zygotic embryogenesis pathway. In contrast to previously described regeneration systems from individual zygotes of higher plants, this is the first study in which direct embryo formation is reproducibly obtained without intermediate tissue dedifferentiation. Most embryos germinated when transferred to regeneration medium, and later formed phenotypically normal, fully fertile plants. Regenerants were confirmed to be derived from the implanted zygotes by means of AFLP and/or morphological analyses. Although zygote implantation has long been established as a useful method in sexual animal reproduction, an equivalent technique for plants is described here for the first time. Since the zygotes enter the embryogenic pathway directly, the genome is presumably as stable as during embryogenesis in planta . With this new approach, isolated wheat zygotes are accessible to micromanipulation without affecting their subsequent embryonic development.     

Herpetomonas megaseliae, Crithidia fasciculata, and Leptomonas collosoma (Kinetoplastida, Trypanosomatidae) in Feces of Lizards Fed Culture Forms of the Flagellates

ABSTRACT. Herpetomonas megaseliae, Crithidia fasciculata , and Leptomonas collosoma from culture survived gut passage in Anolis carolinensis following their ingestion by this lizard. Maximum persistence of H. megaseliae in lizards, as detected by fecal culture, was seven days. No invasion of tissues by H. megaseliae could be detected by means of sectioned material, stained impression slides, or cultures inoculated with material from organs. Crithidia fasciculata was evident in cloacal fluid for up to three days in wet mount preparations. Leptomonas collosoma was observed in feces 24 h after the organisms were fed to lizards. Both C. fasciculata and L. collosoma were cultured from feces of lizards fed the parasites 24 h earlier. Herpetomonas megaseliae was differentiated in lizard feces, with greater than 40% of the forms observed being paramastigotes or opisthomastigotes. Truncate, semispherical forms resembling choanomastigotes were seen, but the kinetoplast was posterior to the nucleus in some of these. Many forms showed extensive coiling of the axoneme within the body of the flagellate. Choanomastigotes and spheromastigotes of C. fasciculata and promastigotes, sphero-mastigotes and amastigotes of L. collosoma were also observed in the feces.     

A bacterial homolog to the mitochondrial enoyl-CoA hydratase.

A 257-amino acid (aa) open reading frame in the photosynthetic bacterium, Rhodobacter capsulatus, shows significant homology to the mitochondrial enoyl-CoA hydratase (290 aa). This similarity in size and sequence suggests that R. capsulatus oxidizes fatty acids using specific components, more like the mitochondrial system than the multifunctional component system of Escherichia coli.     

Immunological analysis of the heme proteins present in aerobically grown Escherichia coli.

Immunological methods were used to obtain information about Escherichia coli heme proteins. There is a membrane-bound catalase which consists of a single subunit (as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoretic analysis) which is also present in the soluble fraction. Antibodies raised against purified, soluble cytochrome b562 showed that this cytochrome is not related to any of the membrane-bound cytochromes, including the b562 component of the cytochrome o complex. Cytochrome b556 is immunologically unrelated to the cytochrome b556 NR associated with the nitrate reductase system. Cytochrome b556 and cytochrome o are not present in a constant ratio in the membrane.     

Studies of the ligand binding to cholera toxin, I. The lipophilic moiety of sialoglycolipids.

The fixation of cholera toxin by ganglioside GGtet1 is dependent on the nature of the carbohydrate as well as the lipid moiety of the glycolipid. The role of the lipid in binding to the toxin investigated with synthetic ganglioside analogues (gangliosidoides). The interaction between glycolipid and toxin was followed by precipitate formation, by inhibition of toxicity and in polyacrylamide gel electrophoresis. For specific precipitation, an aliphatic hydrocarbon chain at least 14 C-atoms in length is required. Some of the gangliosidoides form high molecular weight complexes with cholera toxin at lower molar ratios of ligand to protein than the natural compound. None of the synthetic gangliosidoides equalled natural ganglioside in its ability to inhibit the effects of the toxin in vivo, but some did show considerable inhibitory activity ih monosialo-gangliotetraose or corresponding sialo-glycolipids prevents the easy degradation of the B-protein of cholera toxin into protein subunits by sodium dodecylsulfate.