Effects of Pre-Treatments with Abscisic Acid and/or Benzyladenine on Gas Exchange of French Bean, Sugar Beet, and Maize Leaves During Water Stress and After Rehydration

Net photosynthetic rate (P_N), transpiration rate (E), and stomatal conductance (g_s) during water stress and after rehydration were measured in Phaseolus vulgaris, Beta vulgaris, and Zea mays. Immediately before imposition of water stress by cessation of watering, plants were irrigated with water (control), 100 M abscisic acid (ABA), and/or 10 M N⁶-benzyladenine (BA). In all three species, application of ABA decreased g_s, E, and P_N already 1 h after application. However, during water stress g_s, E, and P_N in plants pre-treated with ABA remained higher than in plants pre-treated with water. Positive effects of ABA application were observed also after rehydration. In contrast, the effects of pre-treatment with BA were species-specific. While in bean plants BA application ameliorated negative effect of water stress, only very slight effects were observed in maize, and in sugar beet BA even aggravated the effects of water stress.     

Selection on flowering time in Mediterranean high-mountain plants under global warming

Under climate warming, plants will undergo novel selective pressures to adjust reproductive timing. Adjustment between reproductive phenology and environment is expected to be higher in arctic and alpine habitats because the growing season is considerably short. As early- and late-flowering species reproduce under very different environmental conditions, selective pressures on flowering phenology and potential effects of climate change are likely to differ between them. However, there is no agreement on the magnitude of the benefits and costs of early- vs. late-flowering species under a global warming scenario. In spite of its relevance, phenotypic selection on flowering phenology has rarely been explored in alpine plants and never in Mediterranean high mountain species, where selective pressures are very different due to the summer drought imposed over the short growth season. We hypothesized that late-flowering plants in Mediterranean mountains should present stronger selective pressures towards early onset of reproduction than early-flowering species, because less water is available in the soil as growing season progresses. We performed selection analyses on flowering onset and duration in two high mountain species of contrasting phenology. Since phenotypic selection can be highly context-dependent, we studied several populations of each species for 2 years, covering their local altitudinal ranges and their different microhabitats. Surrogates of biotic selective agents, like fruitset for pollinators and flower and fruit loss for flower and seed predators, were included in the analysis. Differences between the early- and the late-flowering species were less than expected. A consistent negative correlational selection of flowering onset and duration was found affecting plant fitness, i.e., plants that bloomed earlier flowered for longer periods improving plant fitness. Nevertheless, the late-flowering species may experience higher risks under climate warming because in extremely warm and dry years the earlier season does not bring about a longer flowering duration due to summer drought.     

In vitro Culture of Medicago arborea L. Anthers: Initial Response

High production of viable somatic embryos was obtained from cultured anthers in the second phase of meiosis, using microscopic level observations of tetrads. The medium with the greatest embryogenic efficiency was H6, composed of Murashige and Skoog (MS) medium with 2 mg l⁻¹ of 2,4-dichlorophenoxyacetic acid (2,4-D) and 0.5 mg l⁻¹ of kinetin. All (100%) of the somatic embryos obtained germinated and produced 63% green and 37% albino seedlings. In general, embryogenic calli had a higher ion concentration than non-embryogenic calli, with the exception of calcium whose concentration was higher in non-embryogenic calli. The calli induced in the different media differed in their sucrose and starch compositions. The most embryogenic medium H6-induced calli with the highest sucrose concentration and the lowest starch concentration, before visible embryos were observed. In the leaves of the albino seedlings, sucrose concentrations were very high while those of starch were very low. Ion concentrations were also lower in albino plants than in the leaves of green seedlings, with the exception of calcium, whose concentration was higher. Most of the albino individuals were homozygous, even when their progenitors were heterozygous, thereby confirming their haploid nature.     

Laccase detoxification of steam-exploded wheat straw for second generation bioethanol

In this work we compared the efficiency of a laccase treatment performed on steam-exploded wheat straw pretreated under soft conditions (water impregnation) or harsh conditions (impregnation with diluted acid). The effect of several enzymatic treatment parameters (pH, time of incubation, laccase origin and loading) was analysed. The results obtained indicated that severity conditions applied during steam explosion have an influence on the efficiency of detoxification. A reduction of the toxic effect of phenolic compounds by laccase polymerization of free phenols was demonstrated. Laccase treatment of steam-exploded wheat straw reduced sugar recovery after enzymatic hydrolysis, and it should be better performed after hydrolysis with cellulases. The fermentability of hydrolysates was greatly improved by the laccase treatment in all the samples. Our results demonstrate the action of phenolic compounds as fermentation inhibitors, and the advantages of a laccase treatment to increase the ethanol production from steam-exploded wheat straw.     

Risk factors associated with negative in-vivo diagnostic results in bovine tuberculosis-infected cattle in Spain

Background

Despite great effort and investment incurred over decades to control bovine tuberculosis (bTB), it is still one of the most important zoonotic diseases in many areas of the world. Test-and-slaughter strategies, the basis of most bTB eradication programs carried out worldwide, have demonstrated its usefulness in the control of the disease. However, in certain countries, eradication has not been achieved due in part to limitations of currently available diagnostic tests. In this study, results of in-vivo and post-mortem diagnostic tests performed on 3,614 animals from 152 bTB-infected cattle herds (beef, dairy, and bullfighting) detected in 2007–2010 in the region of Castilla y León, Spain, were analyzed to identify factors associated with positive bacteriological results in cattle that were non-reactors to the single intradermal tuberculin test, to the interferon-gamma (IFN-γ) assay, or to both tests applied in parallel (Test negative/Culture + animals, T-/C+). The association of individual factors (age, productive type, and number of herd-tests performed since the disclosure of the outbreak) with the bacteriology outcome (positive/negative) was analyzed using a mixed multivariate logistic regression model.

Results

The proportion of non-reactors with a positive post-mortem result ranged from 24.3% in the case of the SIT test to 12.9% (IFN-γ with 0.05 threshold) and 11.9% (95% CI 9.9-11.4%) using both tests in parallel. Older (>4.5 years) and bullfighting cattle were associated with increased odds of confirmed bTB infection by bacteriology, whereas dairy cattle showed a significantly lower risk. Ancillary use of IFN-γ assay reduced the proportion of T-/C + animals in high risk groups.

Conclusions

These results demonstrate the likelihood of positive bacteriological results in non-reactor cattle is influenced by individual epidemiological factors of tested animals. Increased surveillance on non-reactors with an increased probability of being false negative could be helpful to avoid bTB persistence, particularly in chronically infected herds. These findings may aid in the development of effective strategies for eradication of bTB in Spain.     

The lymphocyte receptor CD6 interacts with syntenin-1, a scaffolding protein containing PDZ domains

CD6 is a type I membrane glycoprotein expressed on thymocytes, mature T and B1a lymphocytes, and CNS cells. CD6 binds to activated leukocyte cell adhesion molecule (CD166), and is considered as a costimulatory molecule involved in lymphocyte activation and thymocyte development. Accordingly, CD6 partially associates with the TCR/CD3 complex and colocalizes with it at the center of the mature immunological synapse (IS) on T lymphocytes. However, the signaling pathway used by CD6 is still mostly unknown. The yeast two-hybrid system has allowed us the identification of syntenin-1 as an interacting protein with the cytoplasmic tail of CD6. Syntenin-1 is a PDZ (postsynaptic density protein-95, postsynaptic discs large, and zona occludens-1) domain-containing protein, which functions as an adaptor protein able to bind cytoskeletal proteins and signal transduction effectors. Mutational analyses showed that certain amino acids of the most C-terminal sequence of CD6 (-YDDISAA) and the two postsynaptic density protein-95, postsynaptic discs large, and zona occludens-1 domains of syntenin-1 are relevant to the interaction. Further confirmation of the CD6-syntenin-1 interaction was obtained from pull-down and co-immunoprecipitation assays in mammalian cells. Image analyses also showed that syntenin-1 accumulates at CD6 caps and at the IS. Therefore, we propose that syntenin-1 may function as a scaffolding protein coupling CD6 and most likely other lymphocyte receptors to cytoskeleton and/or signaling effectors during IS maturation.     

Regulation of AMPA Receptor Activity, Synaptic Targeting and Recycling: Role in Synaptic Plasticity

The alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors for the neurotransmitter glutamate are oligomeric structures responsible for most fast excitatory responses in the central nervous system. The activity of AMPA receptors can be directly regulated by protein phosphorylation, which may also affect the interaction with intracellular proteins and, consequently, their recycling and localization to defined postsynaptic sites. This review focuses on recent advances in understanding the dynamic regulation of AMPA receptors, on a short- and long-term basis, and its implications in synaptic plasticity.     

Substance P and acetylcholine are co-localized in the pathway mediating mucociliary activity in Rana pipiens

Mucociliary activity is an important clearance mechanism in the respiratory system of air breathing vertebrates. Substance P (SP) and acetylcholine play a key role in the stimulation of the mucociliary transport in the frog palate. In this study, retrograde neuronal tracing was combined with immunocytochemistry for SP and choline acetyl transferase (ChAT) in the trigeminal ganglion and for neurokinin-1 receptor (NK1R) in the palate of Rana pipiens. The cells of origin of the palatine nerve were identified in the trigeminal ganglion using the retrograde tracer Fluorogold (FG). Optimal labeling of FG cells in the trigeminal ganglion was obtained at 96 h of exposure. Immunoflorescent shows that SP and acetylcholine are co-localized in 92% of the cells labeled with FG in the trigeminal ganglion. NK1 receptors were found in the membrane of epithelial and goblet cells of the palate. Ultrastructural study of the palate showed axonal-like endings with vesicles in connection with epithelial and goblet cells. These results further support the concerted action of both neurotransmitters in the regulation of mucociliary activity in the frog palate.     

Repeated DNA sequences in the microbat species Miniopterus schreibersi (Vespertilionidae; Chiroptera)

Repetitive DNA sequences represent a substantial component of eukaryotic genomes. These sequences have been described and characterized in many mammalian species. However, little information about repetitive DNA sequences is available in bat species. Here we describe an EcoRI family of repetitive DNA sequences present in the species Miniopterus schreibersi. These repetitive sequences are 57.85%, A-T rich, organized in tandem, and with a monomer unit length of 904 bp. Methylation analysis using the isoesquizomer pair MspI and HpaII indicates that the cytosines present in the sequences CCGG are partially methylated. Furthermore, Southern blot analysis demonstrated that these DNA sequences are absent in the genomes of four related microbat species and suggest that it could be specific to the M. schreibersi genome.     

Species concept and morphological differentiation of strains traditionally assigned to Micrasterias truncata

The morphological and molecular differentiation of the Micrasterias truncata (Corda) ex Bréb species complex was investigated. In total, 17 strains traditionally assigned to M. truncata were isolated from different European localities (Czech Republic, southwest France, Ireland), and obtained from public culture collections. In addition, strains of the morphologically similar species, M. decemdentata (Nägeli) W. Archer and M. zeylanica F. E. Fritsch, were also included. Molecular phylogenetic analysis based on trnG^ucc intron sequences revealed five well supported clades. Two Australian strains assigned to M. truncata var. pusilla G. S. West formed a lineage sister to M. zeylanica. This was evident from a concatenated phylogeny based on small subunit rDNA and trnG^ucc intron sequences. The isolated position of these strains was also illustrated by parallel landmark‐based geometric morphometric analysis of cell shapes. The strains NIES 783 and NIES 784 probably represent a separate species. Particular analysis, including additional strains, is needed to resolve the relationship inside this lineage. The second phylogenetic lineage, containing two strains of M. truncata var. semiradiata (Kützing) Wolle, was also different from other strains on the basis of morphometric data. We suggest recognizing this variety as a separate species, Micrasterias semiradiata L.A. Brébisson ex F. T. Kützing. The remaining three clades formed a firmly supported group of the ‘core’M. truncata recognized by both molecular markers. However, neither any morphological, morphometric, nor geographical pattern was detected among members of these three clades. This pattern could be caused by a relatively recent origin of these lineages that may represent a sympatric, truly cryptic species. Strains attributable to traditional morphologically defined variety M. truncata var. neodamensis were nested within the ‘core’M. truncata.