Estimating Ecosystem Metabolism to Entire River Networks

Ecosystems - River ecosystem metabolism (REM) is a promising cost-effective measure of ecosystem functioning, as it integrates many different ecosystem processes and is affected by both rapid...     

Divergence with gene flow is driven by local adaptation to temperature and soil phosphorus concentration in teosinte subspecies (Zea mays parviglumis and Zea mays mexicana)

Patterns of genomic divergence between hybridizing taxa can be heterogeneous along the genome. Both differential introgression and local adaptation may contribute to this pattern. Here, we analysed two teosinte subspecies, Zea mays ssp. parviglumis and ssp. mexicana, to test whether their divergence has occurred in the face of gene flow and to infer which environmental variables have been important drivers of their ecological differentiation. We generated 9,780 DArTseqTM SNPs for 47 populations, and used an additional data set containing 33,454 MaizeSNP50 SNPs for 49 populations. With these data, we inferred features of demographic history and performed genome wide scans to determine the number of outlier SNPs associated with climate and soil variables. The two data sets indicate that divergence has occurred or been maintained despite continuous gene flow and/or secondary contact. Most of the significant SNP associations were to temperature and to phosphorus concentration in the soil. A large proportion of these candidate SNPs were located in regions of high differentiation that had been identified previously as putative inversions. We therefore propose that genomic differentiation in teosintes has occurred by a process of adaptive divergence, with putative inversions contributing to reduced gene flow between locally adapted populations.     

Intracellular accumulation of amino acids increases synaptic potentials in rat hippocampal slices

Amino Acids - The application of high concentrations of taurine induces long-lasting potentiation of synaptic responses and axon excitability. This phenomenon seems to require the contribution of a...     

Substrate specificity of the phenolic acid decarboxylase from Lactobacillus plantarum and related bacteria analyzed by molecular dynamics and docking

Journal of Plant Biochemistry and Biotechnology - The phenolic acid decarboxylase (PAD) is a 44 kDa homodimeric, thermolabile and acid-resistant enzyme that some bacteria have developed as...     

Maize seedlings produced from dry seeds exposed to liquid nitrogen display altered levels of shikimate pathway compounds

In light of climate change and risks of food insecurity, it is becoming increasingly important to preserve plant germplasm in genebanks. Storage of seeds, particularly via cryopreservation, is one of the most proficient methods for ex situ plant germplasm conservation. Whilst seed cryo-banking can have little, to no, or even beneficial effects on subsequent seedling vigor in some species, it can lead to a number of plant abnormalities (morphological and physiological). This study investigated the effects of maize seed cryopreservation on seedling growth (until 14 d) and levels of selected amino acids produced in the shikimate pathway, a major link between primary and secondary metabolism. Seed cryopreservation reduced FW in recovered seedlings, reduced caffeic acid (2.5-fold decrease), and increased levels of all other shikimate pathway–related compounds assessed: phenylalanine (2.9-fold increase), tyrosine (2.6-fold increase), and shikimic (2.1-fold increase) and protocathecuic (3.1-fold increase) acids in cotyledons. Our results suggest that maize seed cryopreservation results in seedlings that exhibit signs of an ‘overly’ efficient and caffeic acid–deficient shikimate pathway, possibly related to their reduced growth during a highly vulnerable growth stage. However, these metabolic abnormalities manifested most severely in the maternal (cotyledonary), as opposed to vegetative (roots, stems, and leaves), tissues and hence are likely to disappear when the seedlings shed the cotyledons and become completely autotrophic.

     

Morphogenesis and in vitro production of caffeoylquinic and caffeic acids in Baccharis conferta Kunth

We established a protocol for the in vitro propagation of Baccharis conferta Kunth. This plant is used to treat gastrointestinal problems, cramps, pain, respiratory problems, and insect bites. A high rate of shoot multiplication was obtained from nodal segments on Murashige and Skoog (MS) culture medium. The shoots regenerated roots without exogenous plant growth regulators (PGRs). All explants of wild leaves on MS medium containing 5 μM of thidiazuron (TDZ) produced friable callus. An organogenic response was achieved after 3 wk of culture when callus segments were transferred to MS medium containing a combination of plant growth regulators (PGRs): either (i) 5 μM indole butyric acid (IBA) + 5 μM kinetin (KIN) or (ii) 0.5 μM IBA + 1.10 μM benzylaminopurine (BAP). The morphogenetic responses of callus were characterized by scanning electron microscopy. Shoots regenerated from callus and formed roots on MS medium without PGRs. The micropropagated plantlets and the organogenic callus showed similar chemical profiles in HPLC-mass spectrometry analyses. The main compounds present in the cultures were caffeoylquinic acids. Only plantlets contained small amounts of triterpenes (erythrodiol and ursolic acid). These findings will be useful for the micropropagation of this important native resource, and for further studies on its biology.

     

High-efficiency somatic embryogenesis of a broad range of Brazilian Saccharum spp. hybrids (sugarcane) varieties using explants from previously established in vitro plants

In Vitro Cellular & Developmental Biology - Plant - The current study assessed the embryogenic potential of different Brazilian Saccharum spp. hybrid (sugarcane) varieties, using explants from...