Isoperoxidases from tobacco tissue cultures

Two anodic isoperoxidases (A₁ and A₂) from tobacco tissue culture W-38 and two cathodic isoperoxidases (C₃ and C₄) from tobacco suspension culture WR-132 have been separated and characterized. Molecular weights for each of the isoperoxidases have been determined by two different methods. Only C₄ contained a carbohydrate component. The substrate specificity and the pH optima for the four enzymes with each of five substrates were determined.     

Population studies in Artemisia tridentata ssp. vaseyana: Chromosome numbers and sesquiterpene lactone races

The sesquiterpene lactones and chromosome numbers for three chemical races of Artemisia tridentata ssp. vaseyana have been examined from four populations in western Montana. TLC analysis of the sesquiterpene lactones in the seeds and seed producing parents demonstrated that genetic exchange does occur between sympatric sesquiterpene lactone chemical races. However, other evidence suggests that introgression between these races is restricted to zones of sympatry. There appears to be no correlation between chromosome numbers and sesquiterpene lactone races.     

NMR study of in vivo RIF-1 tumors: Analysis of perchloric acid extracts and identification of 1H, 31P and 13C resonances

Perchloric acid extracts of radiation-induced fibrosarcoma (RIF-1) tumors grown in mice have been analyzed by multinuclear NMR spectroscopy and by various chromatographic methods. This analysis has permitted the unambiguous assignment of the ³¹P resonances observed in vivo to specific phosphorus-containing metabolites. The region of the in vivo spectra generally assigned to sugar phosphates has been found in RIF-1 tumors to contain primarily phosphorylethanolamine and phosphorylcholine rather than glycolytic intermediates. Phosphocreatine was observed in extracts of these tumor cells grown in culture as well as in the in vivo spectra, indicating that at least some of the phosphocreatine observed in vivo arises from the tumor itself and not from normal tissues. In the ³¹P-NMR spectra of the perchloric acid extract, resonances originating from purine and pyrimidine nucleoside di- and triphosphate were resolved. HPLC analyses of the nucleotide pool indicate that adenine derivatives were the most abundant components, but other nucleotides were present in significant amounts. The ¹H and ¹³C resonance assignments of the majority of metabolites present in RIF-1 extracts have also been made. Of particular importance is the ability to observe lactate, the levels of which may provide a noninvasive measure of glycolysis in these cells in both the in vivo and in vitro states. In addition, the aminosulfonic acid, taurine, was found in high levels in the tumor extracts.     

Homing pigeon orientation influenced by deflected winds at home loft

Summary An attempt to repeat studies performed by Baldaccini et al. (1975b) in which pigeons exhibited predictably deviated mean vanishing bearings after prolonged exposure to deflected wind flow is reported. In four sets of pooled release data, deflections in mean bearings as predicted by the olfactory hypothesis of pigeon homing were observed. It is concluded that the time spent in such deflected-wind environments significantly alters some component of the birds' initial orientation mechanism.The authors wish to thank Howard French and Clarence Tilton for their help in construction details and André Gobert for his contributions and assistance. Our appreciation is also extended to Douglas McCorkle, Irene Brown, Michael Weiler, Sean Tunis, Angela Lui, Daniel Polikoff, and Scott Smith for their assistance in conducting test releases and in timing-in returning birds. The participation of the Italian authors was supported jointly by the Italian Ministry of Public Education and the Cassa di Risparmio di Pisa. Additional support for this study came from a National Science Foundation Grant No. BMS 75-18905 A02 to William T. Keeton.     

Amphicarpic plants: definition,ecology, geographic distribution,systematics, life history,evolution and use in agriculture

Although most plants produce all of their fruits (seeds) aboveground, amphicarpic species produce fruits (seeds) both above‐ and belowground. Our primary aims were to determine the number of reported amphicarpic species and their taxonomic, geographic, life form and phylogenetic distribution, to evaluate differences in the life history of plants derived from aerial and subterranean seeds, to discuss the ecological and evolutionary significance of amphicarpy, to explore the use of amphicarpic plants in agriculture, and to suggest future research directions for studies on amphicarpy. Amphicarpy occurs in at least 67 herbaceous species (31 in Fabaceae) in 39 genera and 13 families of angiosperms distributed in various geographical regions of the world and in various habitats. Seeds from aerial and subterranean fruits differ in size/mass, degree of dormancy, dispersal and ability to form a persistent seed bank, with aerial seeds generally being smaller, more dormant and more likely to be dispersed and to form a seed bank than subterranean seeds. In addition, plants produced by aerial and subterranean seeds may differ in survival and growth, competitive ability and biomass allocation to reproduction. Amphicarpic plants may exhibit a high degree of plasticity during reproduction. Subterranean fruits are usually formed earlier than aerial ones, and plants may produce only subterranean propagules under stressful environmental conditions. Differences in the life histories of plants from aerial and subterranean seeds may be an adaptive bet‐hedging strategy.     

Aerial seed bank in a cold desert annual-ephemeral species: Role of anatomical structure of stem and delayed fruit dehiscence in timing of seed dispersal

Why the fruits are retained on dead upright herbaceous plants and how this relates to seed dispersal and timing of germination remain unclear. Stems of the annual Euclidium syriacum (Brassicaceae) with infructescences bearing indehiscent silicles remain upright after plants die in the spring. We investigated the effect of anatomical structures of stem and pedicle and delayed silicle dehiscence on seed dispersal phenology of this species. For comparison, sections were made of the stem of the annual Goldbachia laevigata (Brassicaceae), which has stems that fall over when plants die. Compared to G. laevigata, the stem of E. syriacum has vascular bundles that are closer together, a thicker xylem and phloem, more fibers, a thicker perimedullary zone and a smaller pith diameter:stem diameter ratio. The thickened pedicle did not form an abcission layer. By late October, 5–20% of seeds were dispersed, depending on the position of infructescences on the plant. Snow covered the plants in late autumn and when it melted in mid-April many of the plants had fallen over, with a high number of seeds germinating in attached silicles; seedlings became rooted in soil. After snowmelt, 14–15% of the silicles on the remaining upright plants contained seeds; all seeds were dispersed by early July. The anatomical structures of the stem and pedicle plus the delayed dehiscence of silicles explain the presence of an aerial seed bank in E. syriacum and delay of germination of many of seeds until spring. Further, pieces of upright plants are broken off and dispersed by wind, which helps to explain the wide distribution of E. syriacum in the cold desert.     

Physiological dormancy in seeds of tropical montane woody species in Hawai`i

Worldwide, there is relatively little information on seed dormancy and germination of tropical montane species. Our aim was to help fill this knowledge gap by conducting seed dormancy/germination studies on woody species from this vegetation zone in Hawai`i. All species had water-permeable seeds with a fully developed embryo. Seeds of 29 species (23 genera) were incubated in light/dark at 15/6, 20/10 and 25/15°C and germination monitored at 2-week intervals for 16–128 weeks. Seeds of Chenopodium oahuense, Dubautia menziesii and Silene lanceolata were non-dormant (ND) and those of 26 other species had physiological dormancy (PD); 10 of the 26 species had conditional PD. The optimum germination temperature regime(s) was (were) 25/15°C, 17 species; 25/10 and 20/10°C, 2; 20/10°C, 6; 20/10 and 15/6°C, 2; and 15/6°C, 2. Worldwide, PD in the woody genera included in our study is more common than ND. In addition to its contribution to the world biogeography of seed dormancy/germination, this study will be useful to conservation biologists who need to germinate seeds of tropical montane species.     

A forward genetic screen identifies Dolk as a regulator of startle magnitude through the potassium channel subunit Kv1.1

The acoustic startle response is an evolutionarily conserved avoidance behavior. Disruptions in startle behavior, particularly startle magnitude, are a hallmark of several human neurological disorders. While the neural circuitry underlying startle behavior has been studied extensively, the repertoire of genes and genetic pathways that regulate this locomotor behavior has not been explored using an unbiased genetic approach. To identify such genes, we took advantage of the stereotypic startle behavior in zebrafish larvae and performed a forward genetic screen coupled with whole genome analysis. We uncovered mutations in eight genes critical for startle behavior, including two genes encoding proteins associated with human neurological disorders, Dolichol kinase (Dolk), a broadly expressed regulator of the glycoprotein biosynthesis pathway, and the potassium Shaker-like channel subunit Kv1.1. We demonstrate that Kv1.1 and Dolk play critical roles in the spinal cord to regulate movement magnitude during the startle response and spontaneous swim movements. Moreover, we show that Kv1.1 protein is mislocalized in dolk mutants, suggesting they act in a common genetic pathway. Combined, our results identify a diverse set of eight genes, all associated with human disorders, that regulate zebrafish startle behavior and reveal a previously unappreciated role for Dolk and Kv1.1 in regulating movement magnitude via a common genetic pathway.     

Production of a Dominant-Negative Fragment Due to G3BP1 Cleavage Contributes to the Disruption of Mitochondria-Associated Protective Stress Granules during CVB3 Infection

Stress granules (SGs) are dynamic cytosolic aggregates containing messenger ribonucleoproteins and target poly-adenylated (A)-mRNA. A key component of SGs is Ras-GAP SH3 domain binding protein-1 (G3BP1), which in part mediates protein-protein and protein-RNA interactions. SGs are modulated during infection by several viruses, however, the function and significance of this process remains poorly understood. In this study, we investigated the interplay between SGs and Coxsackievirus type B3 (CVB3), a member of the Picornaviridae family. Our studies demonstrated that SGs were formed early during CVB3 infection; however, G3BP1-positive SGs were actively disassembled at 5 hrs post-infection, while poly(A)-positive RNA granules persisted. Furthermore, we confirmed G3BP1 cleavage by 3C^pro at Q325. We also demonstrated that overexpression of G3BP1-SGs negatively impacted viral replication at the RNA, protein, and viral progeny levels. Using electron microscopy techniques, we showed that G3BP1-positive SGs localized near mitochondrial surfaces. Finally, we provided evidence that the C-terminal cleavage product of G3BP1 inhibited SG formation and promoted CVB3 replication. Taken together, we conclude that CVB3 infection selectively targets G3BP1-SGs by cleaving G3BP1 to produce a dominant-negative fragment that further inhibits G3BP1-SG formation and facilitates viral replication.