Photocontrol of anthocyanin biosynthesis in tomato

Juvenile anthocyanin biosynthesis has been studied in dark-grown seedlings of tomato (Lycopersicon esculentum Mill.) wild types (WTs) and photomorphogenic mutants. During a subsequent 24-hr period of monochromatic irradiation at different fluence rates of red light (R) the fluence-rate response relationships for induction of anthocyanin in all the WTs are similar, yet complex, showing a response at low fluence rates (LFRR) followed by a fluence rate-dependent high irradiance response (HIR). In the hypocotyl this response is restricted to the sub-epidermal layer of cells. The high-pigment-1 (hp-1) mutant exhibits a strong amplification of both response components. Theatroviolacea (atv) mutant shows strongest amplification of the HIR component. In contrast, a transgenic line overexpressing an oat phytochrome A gene (PHYA3 ⁺) shows a most dramatic amplification of the LFRR component. The far-red light (FR)-insensitive (fri) mutant, deficient in phytochrome A (phyA), lacks the LFRR component whilst retaining a normal HIR. The temporarily R-insensitive (tri) mutant, deficient in phytochrome B1 (phyB1) retains the LFRR, but lacks the HIR. Thehp-1,fri andhp-1,tri double mutant, exhibit amplified, yet qualitatively similar responses to the monogenicfri andtri mutants. Thefri,tri double mutant lacks both response components in R, but a residual response to blue light (B) remains. Similarly, theaurea (au) mutant deficient in phytochrome chromophore biosynthesis and presumably all phytochromes, lacks both response components in the R and FR regions of the spectrum. Experiments at other wavelengths demonstrate that while there is only a small response in the FR spectral region (729 nm) in tomato, there is an appreciable HIR response in the near FR at 704 nm, which is retained in thetri mutant. This suggests that the labile phyA pool participates in the HIR at this wavelength. The intense pigmentation (Ip) mutant appears to be specifically deficient in the B1 induced anthocyanin biosynthesis. Adult plants, grown under fluorescent light/dark cycles, show a reduction of anthocyanin content of young developing leaves upon application of supplemtary or end-of-day FR. The involvement of different phytochrome species in anthocyanin biosynthesis based on micro-injection studies into theau mutant and studies using type specific phytochrome mutants is discussed.     

Acetylcholine in plants: Presence,metabolism and mechanism of action

Acetylcholine (ACh) has been detected in representatives of many taxonomic groups throughout the plant kingdom. The site of its synthesis in plants is probably young leaves. In some plant species choline acetyltransferase (ChAT) activity has been found. This enzyme showing properties similar to animal ChAT, probably participates in ACh synthesis from its precursors, choline and acetyl-Coenzyme A. Acetylcholinesterase (AChE) activity has also been found in many plant tissues. This enzyme decomposes ACh and exhibits properties similar to animal AChE. The presence of both ChAT and AChE in plant tissues suggests that ACh undergoes similar metabolism in plants as it does in animals. Exogenous ACh affects phytochrome-controlled plant growth and development. Mimicking red light (R), ACh stimulates adhesion of root tips to a glass surface and influences leaf movement and membrane permeability to ions. It also affects seed germination and plant growth. Moreover, ACh can modify some enzyme activity and the course of some metabolic processes in plants. Acetylcholine in the presence of calcium ions (Ca²⁺), like R stimulates swelling of protoplast isolated from etiolated wheat leaves. It is proposed that the primary mechanism of action of ACh in plant cells is via the regulation of membrane permeability to protons (H⁺), potassium ions (K⁺), sodium ions (Na⁺) and Ca²⁺.     

AUV-based classification of benthic communities of the Ningaloo shelf and mesophotic areas

Coral Reefs - Despite a growing understanding of the importance of mesophotic ecosystems, they remain relatively unexplored globally, and particularly in the Indian Ocean. The composition of...     

Experimental retracement of the origins of a protocell

Although Oparin used coacervate droplets from two or more types of polymer to model the first cell, he hypothesized homacervation from protein, consistent with Pasteur and Darwin. Herrera made two amino acids and numerous cell-like structures (sulfobes) in the laboratory, which probably arose from intermediate polymers. Our experiments have conformed with a homoacervation of thermal proteinoid, in which amino acid sequences are determined by the reacting amino acids themselves. All proteinoids that have been tested assemble themselves alone in water to protocells. The protocells have characteristics of life defined by Webster's Dictionary: metabolism, growth, reproduction and response to stimuli in the environment. The protocells are able also to evolve to more modern cells including the initiation of a nucleic acid coding system.Principal spinoffs from the results are revised evolutionary theory, models for protoneurons and networks thereof, and numerous industrial applications of thermal polyamino acids. Life itself has thus been reaffirmed to be rooted in protein, not in DNA nor RNA, which are however crucial to inheritance in modern life as instruction manual (Kornberg).Recognition of the advances have been considerably delayed by the deeply held assumption that life began by chance from random polymerization of amino acids, in contrast to the experimental findings. The concepts of DNA/RNA-first and protein-first are reconciled by a rise-and-fall progression as often seen in biochemical and biological evolution.The fact that amino acids order themselves explains in turn that thermal copolyamino acids are finding numerous applications. The entire sequence of processes in the proteinoid origins theory is now seen to be highly deterministic, in close accord with Einstein.     

Ecological significance and commercial harvesting of drifting and beach-cast macro-algae and seagrasses in Australia: a review

This review provides an overview of aspects of the ecology of drifting and beach-cast macroalgae and marine angiosperms in respect to present and potential commercial use of that resource in Australia. It sets the scene with sections on industries that utilise macro-algae and seagrasses, the ecology of littoral and nearshore sublittoral ecosystems and the processes of deposition of beach-cast macro-algae and seagrasses on beaches. It then describes the major economic macro-algae and seagrasses that occur as beach-cast wrack, with an emphasis on known information on habitat distribution, geographical range, and harvesting issues. Gaps in scientific knowledge are pointed out. The priority areas of future research were found to be: • The importance of beach accumulations of macro-algae and seagrasses on feeding and nesting shorebirds; • Whether available resource allows for ecologically and economically sustainable harvesting; • A survey of present and potential commercial macro-algae and seagrasses: studying biomass, density and annual production rates, interannual variability of recruitment into living stands, the effect of harvesting on trophodynamics and community structure and the stability of the resource base for economically sustainable harvesting; • An assessment of the importance of wrack in recycling nutrients and detritus to nearshore coastal ecosystems at wider geographical scales than previous work. This research should assess the dependence of offshore production on nutrients and detritus that are broken down in beachwracks. This revised version was published online in August 2006 with corrections to the Cover Date.     

Next-Generation Sequencing of a Single Domain Antibody Repertoire Reveals Quality of Phage Display Selected Candidates

Next-Generation Sequencing and bioinformatics are powerful tools for analyzing the large number of DNA sequences present in an immune library. In this work, we constructed a cDNA library of single domain antibodies from a llama immunized with staphylococcal enterotoxin B. The resulting library was sequenced, resulting in approximately 8.5 million sequences with 5.4 million representing intact, useful sequences. The sequenced library was interrogated using sequences of known SEB-binding single domain antibodies from the library obtained through phage display panning methods in a previous study. New antibodies were identified, produced, and characterized, and were shown to have affinities and melting temperatures comparable to those obtained by traditional panning methods. This demonstrates the utility of using NGS as a complementary tool to phage-displayed biopanning as a means for rapidly obtaining additional antibodies from an immune library. It also shows that phage display, using a library of high diversity, is able to select high quality antibodies even when they are low in frequency.     

Red light induced production of gibberellin-like substances in homogenates of etiolated wheat leaves and in suspensions of intact etioplasts

Summary Homogenates of etiolated wheat leaves contain increased levels of acidic gibberellin (GA)-like substances following treatment with red light. Differential centrifugation of homogenates indicates that the response is confined to the 1000 g (or plastid) fraction. Irradiation of suspensions of intact etioplasts also increases the level of extractable GA-like activity. Phytochrome can be detected spectrophotometrically in preparations of etioplasts. The response in etioplasts can be inhibited by chloramphenicol, but not by cycloheximide, and partially by Amo 1618. The GA-like substances produced in etioplasts seem capable of passing into the surrounding medium within 20 min.Abbreviation GA Gibberellin     

Transposition of IS50L activates downstream genes.

A transposition system constructed to detect the transposition of Tn5 to a site upstream of the lacZ gene has revealed that transposition of IS50L can activate downstream genes. Expression is apparently mediated by the NPTII promoter. Transposase produced either by IS50R or by the suppressed IS50L catalyzed transposition of IS50L.     

Temperature-Induced Viral Resistance in Emiliania huxleyi (Prymnesiophyceae)

Annual Emiliania huxleyi blooms (along with other coccolithophorid species) play important roles in the global carbon and sulfur cycles. E. huxleyi blooms are routinely terminated by large, host-specific dsDNA viruses, (Emiliania huxleyi Viruses; EhVs), making these host-virus interactions a driving force behind their potential impact on global biogeochemical cycles. Given projected increases in sea surface temperature due to climate change, it is imperative to understand the effects of temperature on E. huxleyi’s susceptibility to viral infection and its production of climatically active dimethylated sulfur species (DSS). Here we demonstrate that a 3°C increase in temperature induces EhV-resistant phenotypes in three E. huxleyi strains and that successful virus infection impacts DSS pool sizes. We also examined cellular polar lipids, given their documented roles in regulating host-virus interactions in this system, and propose that alterations to membrane-bound surface receptors are responsible for the observed temperature-induced resistance. Our findings have potential implications for global biogeochemical cycles in a warming climate and for deciphering the particular mechanism(s) by which some E. huxleyi strains exhibit viral resistance.