An analysis of tobacco mosaic virus replicative structures synthesized in vitro

Summary The RNA structures synthesized in vitro by a crude enzyme complex from tobacco mosaic virus (TMV)-infected leaves have been analyzed; the major viral-specific products were similar to TMV-replicative form (RF) and-replicative intermediate (RI) in electrophoretic behavior and ribonuclease sensitivity. Synthesis of these RF-like and RI-like structures neither required nor responded to added viral RNA, but did require all four ribonucleotide triphosphates. Enriched radiolabeled RF-like and RI-like RNA fractions were isolated from non-denaturing agarose gels by electroelution and hybridized to a collection of TMV sequences cloned into bacteriophage M13. Enriched RF-RNA hybridized to sequences of both plus and minus polarity, while enriched RI-RNA hybridized only to inserts of minus polarity, indicating only plus strand synthesis in this fraction. Most of the label incorporated into the plus strand of the enriched RF-RNA was found near the 3-end of this strand, while most of the label incorporated into enriched RI-RNA was found several hundred bases from the 5-end of the plus strand.Paper presented at the first International Congress of Plant Molecular Biology (Savannah, GA, 1985).     

ISPMB 6th International Congress of Plant Molecular Biology

Announcement

ISPMB 6th International Congress of Plant Molecular Biology     

Restoration of male fertileNicotiana by fusion of protoplasts derived from two different cytoplasmic male-sterile cybrids

Summary Using the donor-recipient protoplast-fusion technique, we have recently constructed several alloplasmic-like lines ofNicotiana in which the original cytoplasms (or part of them) of eitherN. tabacum orN. sylvestris were replaced respectively, either byN. undulata or byN. bigelovii cytoplasms. These cybridizations resulted in two kinds of cytoplasmic male-sterile (CMS) cybrid plants:N. tabacum withN. undulata-like cytoplasm andN. sylvestris withN. bigelovii-like cytoplasm. Fusion of protoplasts, derived from the above two CMS types, by the donor-recipient technique, lead to the recovery of 21 cybrid calli. One of these regenerated a cybrid with fertile pollen but having shortened filaments and slighly tappered anthers. Self pollination of the latter cybrid resulted in a second generation progeny having almost normal filaments and anthers. Further selfings produced a third generation in which numerous plants had normal stamens and fertile pollen. Mitochondrial DNA (mtDNA) analysis of second and third generation progenies revealed a novel pattern which differed from each of the parental CMS cybrids and also from the mtDNA of normal, male-fertileNicotiana species. The results suggest that mtDNA recombination between different types of CMS can lead to restoration of male-fertility.Paper presented at the 1st Plant Molecular Biology Congress, Savannah, Georgia, Oct./Nov. 1985.     

Unusual characteristics of Codium fragile chloroplast DNA revealed by physical and gene mapping

Summary A complete physical map of the Codium fragile chloroplast genome was constructed and the locations of a number of chloroplast genes were determined. Several features of this circular genome are unusual. At 89 kb in size, it is the smallest chloroplast genome known. Unlike most chloroplast genomes it lacks any large repeat elements. The 8 kb spacer region between the 16 S and 23 S rRNA genes is the largest such spacer characterized to date in chloroplast DNA. This spacer region is also unusual in that it contains the rps12 gene or at least a portion thereof. Three regions polymorphic for size are present in the Codium chloroplast genome. The psbA and psbC genes map closely to one of these regions, another region is in the spacer between the 16 S and 23 S rRNA genes and the third is very close to or possibly within the 16 S rRNA gene. The gene order in the Codium genome bears no marked resemblance to either the consensus vascular plant order or to that of any green algal or bryophyte genome. Present address: Department of Biology, Texas A&M University, College Station, TX 77843; USA     

Announcing the call for the Special Issue on the 20th International Congress of the International Union of Pure and Applied Biophysics (IUPAB)—virtual meeting,October 2021

This Commentary describes a call for submissions for the upcoming Special Issue focused on the science presented at the 20^th IUPAB Congress to be held in conjunction with the 45^th Annual Meeting of the Brazilian Biophysical Society and the 49^th Annual Meeting of the Brazilian Society for Biochemistry and Molecular Biology.

Due to the COVID-19 pandemic, the 20^th International IUPAB Congress will take place as a virtual meeting this year from October 4 to 8, 2021. This triennial IUPAB Congress will be held in loose conjunction with the 45^th Annual Meeting of the Brazilian Biophysical Society and the 49^th Annual Meeting of the Brazilian Society for Biochemistry and Molecular Biology. To act as a complement to this virtual meeting, the Biophysical Reviews journal will base a Special Issue on the scientific topics of the meeting contributors selected from the range of invited speakers and poster presenters. This Special Issue will also work to highlight the host country’s (Brazil) National Biophysical Society. Finally, this Special Issue will also serve to publish the meeting abstracts in supplemental form.Review articles from IUPAB Congress speakers and poster presenters to the IUPAB Congress and associated conferences (the 45^th Annual Meeting of the Brazilian Biophysical Society and the 49^th Annual Meeting of the Brazilian Society for Biochemistry and Molecular Biology) are solicited. Similar to the SI based on the 19^th IUPAB Congress held in Edinburgh summarizing Commentaries from session chairs are also requested (Hall and dos Remedios 2017). The Special Issue for the 20^th IUPAB International Congress will be prepared and edited by the current authors (Rosangela Itri, Mauricio Baptista, Richard Garratt, and Antonio Jose Costa-Filho).     

The flowering-time geneFT and regulation of flowering inArabidopsis

Transition from vegetative to reproductive development (flowering) is one of the most important decisions during the post-embryonic development of flowering plants. More than twenty loci are known to regulate this process inArabidopsis. Some of these flowering-time genes may act at the shoot apical meristem to regulate its competence to respond to floral inductive signals and floral evocation. Genetic and phenotypic analyses of mutants suggest that the late-flowering geneFT may be a good candidate for such genes. To test this, we have cloned theFT gene using aFT-deficiency line associated with a T-DNA insertion. Cloned genes and loss-of-function mutants in hand, it is now possible to analyse the role ofFT and other genes in flowering at the biochemical and cellular levels as well as at the genetic level. The deduced FT protein has homology with TFL1 and CEN proteins believed to be involved in regulation of inflorescence meristem identity. Phylogenetic analysis suggests that theFT group and theTFL1/CEN group of genes diverged before the diversification of major angiosperm clades. This raises the interesting question of the evolutionary relationship between the regulation of vegetative/reproductive switching in the shoot apical meristem and the regulation of inflorescence architecture in angiosperms. The extended abstract of a paper presented at the 13th International Symposium in Conjugation with Award of the International Prize for Biology “Fronitier of Plant Biology”     

First World Congress of Cellular and Molecular Biology

Announcement

First World Congress of Cellular and Molecular Biology     

Sticking together: Cell adhesion interactions inArabidopsis reproduction

We review the role of the extracellular matrix in transducing environmental signals, focusing on adhesion molecules in plants and animals. Plant reproduction is ideal for investigating cell-cell interactions; recently-describedArabidopsis thaliana mutants defective in cell adhesion during reproduction promise to illuminate unique cell signaling mechanisms. The exteneded abstract of a paper presented at the 13th International Symposium in Conjugation with Award of the International Prize for Biology “Frontier of Plant Biology”     

The cryptochrome family of blue/UV-A photoreceptors

The structural and functional properties of cryptochrome blue light receptors ofArabidopsis thaliana are described. Cryptochromes from ferns and algae, as well as a cryptochrome-like sequences from mammals, are discussed. The extended abstract of a paper presented at the 13th International Symposium in Conjugation with Award of the International Prize for Biology “Frontier of Plant Biology”     

DNA sequences in chromosomes 11 and VII code for pyruvate carboxylase isoenzymes in Saccharomyces cerevisiae: analysis of pyruvate carboxylase-deficient strains

Summary A gene encoding pyruvate carboxylase has previously been isolated from Saccharomyces cerevisiae. We have isolated a second gene, PYC2, from the same organism also encoding a pyruvate carboxylase. The gene PYC2 is situated on the right arm of chromosome II between the DUR 1, 2 markers and the telomere. We localized the previously isolated gene, which we designate PYC1, to chromosome VII. Disruption of either of the genes did not produce marked changes in the phenotype. However, simultaneous disruption of both genes resulted in inability to grow on glucose as sole carbon source, unless aspartate was added to the medium. This indicates that in wild-type yeast there is no bypass for the reaction catalysed by pyruvate carboxylase. The coding regions of both genes exhibit a homology of 90% at the amino acid level and 85% at the nucleotide level. No appreciable homology was found in the corresponding flanking regions. No differences in the K _m values for ATP or pyruvate were observed between the enzymes obtained from strains carrying inactive, disrupted versions of one or other of the genes.A preliminary report of this work was presented at the 15th International Conference on Yeast Genetics and Molecular Biology, The Hague, Netherlands. Abstract appeared in Yeast 6, S-240 (1990)     

Development of inflorescences inArabidopsis thaliana

Those mutants were studied whose defects resulted in the morphological changes of inflorescences inArabidopsis thaliana. We characterized newly isolatedcorymbosa mutants andacaulis5 mutants. Thecorymbosa1-1 mutation was caused by the defects in the elongation of pedicels and the previously identifiederecta mutation belonged to this class. Thecorymbosa2-1 mutation was caused mainly by the increase of the number of the floral buds in the inflorescence. The expression of theERECTA gene whose defect resulted to the corymbose inflorescence was analyzed. TheERECTA gene was expressed in subsets of cells in both the peripheral zone and central zone and was thought to have important role for the development of inflorescences. The phenotypes of theacaulis5 mutation was pronounced just after the transition from the vegetative to reproductive growth phase. We found that the expressions of the genes for EXGT-A1 and γ-TIP were drastically reduced in theacaulis5 mutants. The extended abstract of a paper presented at the 13th International Symposium in Conjugation with Award of the International Prize for Biology “Frontier of Plant Biology”     

CENTRORADIALIS/TERMINAL FLOWER 1 gene homolog is conserved inN. tabacum, a determinate inflorescence plant

A mutation in theCENTRORADIALIS (CEN) gene ofAntirrhinum and in theTERMINAL FLOWER 1 (TFL1) gene ofArabidopsis causes their indeterminate inflorescence to determinate. We clonedCEN/TFL1 homologs fromNicotiana tabacum, the wild-type of which has a determinate inflorescence. TheCEN gene was expressed in the inflorescnece meristem and kept its inflorescence meristem identity, whereas the tobacco homolog (NCH) was expressed at a low level throughout the plant’s development. AlthoughCEN andNCH are highly homologous genes, they may have been recruited to different developmental functions during their evolution. TwoNCH genes are derived from amphidiploidN. tabacum, but both of them hybridized with its diploid parents,N. sylvestris andN. tomentosiformis. Southern blotting, and the genomic organization ofTFL1 inArabidopsis revealed that anotherCEN homolog exists in the genome ofArabidopsis. These results suggest that there are two copies of theCEN homolog per diploid plant. The extended abstract of a paper presented at the 13th International Symposium in Conjugation with Award of the International Prize for Biology “Frontier of Plant Biology” These two authors contributed to this work equally.     

Genetic pathways controlling carpel development inArabidopsis thaliana

Carpel development inArabidopsis is known to be controlled by the organ identity geneAGAMOUS. However, even in the absence of AGAMOUS function, many carpel properties can arise suggesting that other genes are also involved. Two new carpel genes,CRABS CLAW andSPATULA, have been recognised by their specific disruptions to carpel development in mutant plants. These disruptions suggest thatCRABS CLAW normally plays a role in promoting the growth of specific regions of the carpel wall, whereasSPATULA apparently has a primary function in promoting development of the transmitting tract. When the function of these genes is also compromised along with that ofAGAMOUS in multiply mutant plants, carpelloid properties vanish. ThusAGAMOUS, CRABS CLAW andSPATULA act together in specifying carpel development, although none can do this alone. BecauseSPATULA mutants are epistatic to mutants of another carpel development gene,ETTIN, the latter may normally act by suppressing the action ofSPATULA in specific regions of the developing gynoecium. There is indirect evidence thatETTIN, and another morphogenetic gene,PINOID, act through regulating auxin-induced growth in specific regions of the developing flower, but it is not yet known how this could result in the suppression of SPATULA function. The extended abstract of a paper presented at the 13th International Symposium in Conjugation with Award of the International Prize for Biology “Frontier of Plant Biology”     

2001 Kumho Science International Award in Plant Molecular Biology and Biotechnology Award Presentation ceremony

Appointments and Awards

2001 Kumho Science International Award in Plant Molecular Biology and Biotechnology Award Presentation ceremony     

Programming of cell death during xylogenesis

Death of tracheary elements which compose vessels and tracheids is a typical example of programmed cell death in plants. Anin vitro system usingZinnia mesophyll cells which differentiate directly into tracheary elements has provided various types of data on the cell death process. In this paper, we will summarize recent results obtained using theZinnia system and discuss the programming of cell death during tracheary element differentiation. The extended abstract of a paper presented at the 13th International Symposium in Conjugation with Award of the International Prize for Biology “Frontier of Plant Biology”     

The lipid composition and conversion of tryptamine toN b-acetyltryptamine in aCatharanthus roseus cell line without indole alkaloids

Summary A cell line, NA13-2, was selected as a rapidly growing colony of protoplasts from a UV(254 nm)-fluorescent cell line, NA13-1, which originated from a tryptamine-resistant strain ofCatharanthus roseus NA13. Cell line NA13-2 lost the capability to produce indole alkaloids. Tryptophan fed to these cells was converted toN _b-acetyltryptamine as the major product. The free acetyl coenzyme A content of NA13-2 cells was 50% higher than in the mother cells. The total lipid content of the NA13-2 cells was 2.5-fold that in the NA13 cells. In spite of the similarity in the fatty acid content to that of the mother cell line NA13, the total lipid extract of NA13-2 cells appeared as a wax instead of an oil, resulting from the presence of sterol esters.This paper was presented in part at the Annual Meeting of the Society for Industrial Microbiology, Boston, MA, 1985, and the International Congress of the Plant Tissue Culture Association, Minneapolis, MN, 1986.     

An aberrant plastid ribosomal RNA gene cluster in the root parasite Conopholis americana

The plastid ribisomal RNA (rRNA) operon of the achlorophyllous root parasite Conopholis americana was completely sequenced. Full-length rRNA genes are retained in the gene cluster, but significant divergence has occurred in the 16S, 23S and 5S genes. Both the 16S–23S intergenic spacer and the 4.5S–5S intergenic spacer have suffered substantial deletions, including the two tRNA genes typically found in prokaryotic and plastid 16S–23S spacers.     

Structural features of the plastid ribosomal RNA operons of two red algae: Antithamnion sp. and Cyanidium caldarium

The nucleotide sequences of the plastid 16S rDNA of the multicellular red alga Antithamnion sp. and the 16S rDNA/23S rDNA intergenic spacers of the plastid DNAs of the unicellular red alga Cyanidium caldarium and of Antithamnion sp. were determined. Sequence comparisons support the idea of a polyphyletic origin of the red algal and the higher-plant chloroplasts. Both spacer regions include the unsplit tRNA^Ile (GAU) and tRNA^Ala (UGC) genes and so the plastids of both algae form a homogeneous group with those of chromophytic algae and Cyanophora paradoxa characterized by small-sized rDNA spacers in contrast to green algae and higher plants. Nevertheless, remarkable sequence differences within the rRNA and the tRNA genes give the plastids of Cyanidium caldarium a rather isolated position.