Wood remains from Tel Nami,a middle bronze IIa and late bronze IIb port,local exploitation of trees and levantine cedar trade

Thirteen Middle Bronze Age IIa and four Late Bronze Age IIb (ca. 1950-1750 B.C. and thirteenth century, B.C., respectively)pieces of charcoal or water logged wood were found in the recent excavations of Tel Nami, a small port on the coast near Mount Carmel, Israel. These includedCedrus libani (cedar of Lebanon) (three samples), and local tree species that still grow today in the vicinity of the site—Pinus halepensis (Aleppo pine) (one sample),Olea europaea (olive tree) (five samples),Quercus calliprinos (kermes oak) (three samples),Quercus ithaburensis (Mt. Tabor oak) (four samples), andQuercus sp. (one sample). The discovery of Cedrus libani in a Middle Bronze Age IIa port is one of the earliest published examples of cedar wood from Israel. Together with other artifactual evidence for maritime trade from Tel Nami, this find suggests that a maritime trade in cedar wood existed along the Levantine coast.     

Expanding ecological and evolutionary insights from wild Arabidopsis thaliana accessions

The analytical power of Arabidopsis thaliana genomics has turned its local varieties (accessions) from divergent habitats into important genetic resources. Variant alleles harbored in those accessions are used to identify loci controlling important plant traits with enormous benefits for analytical as well as applied purposes. We argue here that the information derived from Arabidopsis accessions can be further expanded, if a systematic effort for recording the growth conditions of new Arabidopsis accessions is rapidly implemented. The modest and feasible changes in genetic sampling practice that we propose will dramatically increase the quality and quantity of data obtained from Arabidopsis accessions. The broader data set will no longer focus solely on the genetic mechanism within the plant, but will also address the plant''s interaction with its environment. We suggest (a) a modified sampling strategy involving sample size and the recording of additional growth conditions (Appendix) and (b) the establishment of a centralized and expandable database to cover all available information regarding the habitats of Arabidopsis accessions.Key words: adaptation, Arabidopsis, ecology, evolution, genetic resources, sampling strategyThe influence of the immediate abiotic and biotic environment on the evolution of developmental, physiological, reproductive, defense-related and a variety of ecological characteristics of plants is well documented,^1–3 but is rarely connected to the level of individual gene activities. This is partly because for most plants, the genetic dissection of adaptation processes at the individual, population and evolutionary levels is inherently difficult. The current and foreseeable wealth of molecular insights in the Arabidopsis model system could fill this void. With its very wide natural geographic distribution over large parts of Asia and Europe⁴ and it''s more recent (human-induced) colonization of habitats in America, Arabidopsis thaliana provides immediate opportunities for studying adaptation processes in great molecular and genetic detail. Therefore, it is not surprising that Arabidopsis has also been used as a model system for population genetics and ecological adaptation in recent years.^5–8 In a parallel dramatic development, increasing numbers of Arabidopsis accessions are currently being characterized in unprecedented molecular detail to be used as parental lines in QTL mapping studies. These two lines of research could most productively benefit from each other, if habitat information for each accession would become available.An example of a relevant question is: how are environmental variables correlated to phenotypic or gene expression profiles of Arabidopsis accessions? An expandable list of such variables to be recorded at the sampling site would include elevation, aspect (facing north, south, east or west), soil type and soil conditions, rainfall, temperature regime, wind direction and velocity, exposure to sun irradiation, level of shade, UV level, photoperiod, snow cover, local plant communities, herbivore diversity, frequency and pressure, fire history, evidence of various disturbances and apparent diseases. We know, for instance, that various characters, such as vascular structure, fiber length and density, cuticle thickness, stomata density and pigment composition, can be subject to selection even within small, locally restricted populations.^9–12 At a time when phenotypic and molecular profiles of Arabidopsis accession are being scrutinized with ever increasing precision, it would be an inexcusable loss, if the corresponding habitat data for those accessions were simply not recorded or retrievable. It seems evident that with a small, but well-coordinated additional effort, it could be possible to address a much wider array of questions and to direct the power of Arabidopsis genomics and genetics to the study of plant adaptations and evolution. Specifically, we propose that a standard list of environmental data should be provided with each accession of seeds, together with multiple deposited plants as well as electronic images of the exact site and general environment and a precise geographical position (GPS) of the sampling site (see appendix). Precise site documentation may enable re-sampling of populations to study their genetic changes over time.Detailed recording of accession habitats and the collection of multiple plants at each location would reciprocally benefit QTL mapping efforts. First, it would firmly establish that the parental lines of a mapping cross are true natural genotypes. This is important, because any exploitation of natural alleles in breeding and biotechnology should rely in the assumption that these alleles have passed the test of natural selection and are not spontaneous mutants or propagation contaminants. Secondly, emerging correlations between habitat conditions and phenotype can guide accession choices for the establishment of new mapping populations. Phenotyping of accessions for specific cell biological or biochemical traits can be labor intensive. To keep numbers manageable, habitat properties with predictive power would be highly desirable.In summary, we do not consider our suggestions of approximately 30 parameters (see the appendix) to be more than the beginning of a discussion. However, it seems to us that the need for organized habitat characterization and sampling is so urgent that this discussion should begin immediately.     

<Emphasis Type="Italic">Arabidopsis thaliana</Emphasis> as a model for gelatinous fiber formation

Trees and herbaceous plants continuously monitor their position to maintain vertical stem growth and regulate branch orientation. When orientation is altered from the vertical, they form a special type of wood called reaction wood that differs chemically and structurally from normal wood and forces reorientation of the organ or whole plant. The reaction wood of dicotyledons is called tension wood and is characterized by nonlignified gelatinous fibers. The altered chemical and mechanical properties of tension wood reduce wood quality and represent a major problem for the timber and pulping industries. Repeated clipping of the emerging inflorescence stems of Arabidopsis thaliana augments wood formation in organs, including those inflorescence stems that are allowed to develop later. Gravistimulation of such inflorescence stems induces tension wood formation, allowing the use of A. thaliana for a molecular and genetic analysis of the mechanisms of tension wood formation.     

The shared and separate roles of aposematic (warning) coloration and the co-evolution hypothesis in defending autumn leaves

The potential anti-herbivory functions of colorful (red and yellow) autumn leaves received considerable attention in the last decade. The most studied and discussed is the co-evolutionary hypothesis, according to which autumn coloration signals the quality of defense to insects that migrate to the trees in autumn. In addition to classic aposematism (repellency due to signaling unpalatability, non profitability of consumption, or danger for whatever reasons) that operates immediately, this hypothesis also proposes that the reduced fitness of the insects is in their next generation hatching in the spring from eggs laid on the trees in autumn. Supporters of the co-evolutionary hypothesis either posited that this hypothesis differs from visual aposematism or ignored the issue of aposematism. Interestingly, other authors that cited their papers considered the co-evolutionary hypothesis as visual aposematism. Recently, the overlap between the co-evolutionary hypothesis and visual aposematism was finally recognized, with the exception of yellow autumn leaves not signaling defense to aphids, which are known to be attracted to yellow leaves. However, the detailed relationships between these two hypotheses have not been discussed yet. Here I propose that the co-evolutionary hypothesis generally equals visual aposematism in red and yellow autumn leaves towards all herbivores except for yellow not operating with aphids. The co-evolutionary signaling extends beyond classic aposematism because it may operate later and not only immediately. The possibility that for yellow autumn leaves the co-evolutionary hypothesis may also operate via olfactory aposematism should not be dismissed.Key words: aposematic, autumn coloration, co-evolution, defense, evolution, herbivory, treesColorful (red and yellow) autumn leaves dominate large areas of America, Asia and Europe, expressed by thousands of tree, shrub and climber species.^1–5 In the last decade, this phenomenon received considerable scientific attention. For a long time it was a common belief that this coloration is the by-product of the cessation of masking by chlorophylls that degrade in autumn. However, two key theoretical and experimental developments stimulated the recent wave of study of autumn leaf coloration. The first was the recognition that anthocyanins are synthesized de novo in red autumn leaves,^1,2 and the second was the formulation of the anti-herbivory co-evolutionary hypothesis.^6–8The updated version of the co-evolutionary hypothesis⁹ posits that red autumn coloration signals to all types of insects (including aphids) that migrate to the trees in autumn about their chemical defense, lower nutritional quality or imminent leaf fall, or any other characteristic that would induce a lower fitness in the insects. In addition, yellow leaves signals the same to all herbivores except aphids. A special aspect of the co-evolutionary hypothesis is that the reduced fitness of the insects is not only immediate, reducing insect feeding in autumn, but also related to the reduced development of the next generation that hatches in the following spring from eggs laid on the trees in the autumn.⁹ Originally, the co-evolutionary hypothesis addressed both red and yellow autumn leaves.^6–8 However, with the later understanding that yellow leaves usually attract rather than repel aphids,^9–13 the co-evolutionary hypothesis was later restricted to red leaves when aphids are concerned.⁹In addition to other various potential anti-herbivory roles,^14,15 red autumn leaf coloration has several potential physiological functions, such as protection from photoinhibition and photo oxidation, and other physiological functions have been proposed but not agreed upon.^{1,2,9,16–21}     

Why do many galls have conspicuous colors? A new hypothesis

Galls are abnormal plant growth induced by various parasitic organisms, mainly insects. They serve as “incubators” for the developing insects in which they gain nutrition and protection from both abiotic factors and natural enemies. Galls are typically armed with high levels of defensive secondary metabolites. Conspicuousness by color, size and shape is a common gall trait. Many galls are colorful (red, yellow etc.) and therefore can be clearly distinguished from the surrounding host plant organs. Here we outlined a new hypothesis, suggesting that chemically protected galls which are also conspicuous are aposematic. We discuss predictions, alternative hypotheses and experimental tests of this hypothesis.     

Decidual NK cells regulate key developmental processes at the human fetal-maternal interface

Human CD56(bright) NK cells accumulate in the maternal decidua during pregnancy and are found in direct contact with fetal trophoblasts. Several mechanisms have been proposed to explain the inability of NK cells to kill the semiallogeneic fetal cells. However, the actual functions of decidual NK (dNK) cells during pregnancy are mostly unknown. Here we show that dNK cells, but not peripheral blood-derived NK subsets, regulate trophoblast invasion both in vitro and in vivo by production of the interleukin-8 and interferon-inducible protein-10 chemokines. Furthermore, dNK cells are potent secretors of an array of angiogenic factors and induce vascular growth in the decidua. Notably, such functions are regulated by specific interactions between dNK-activating and dNK-inhibitory receptors and their ligands, uniquely expressed at the fetal-maternal interface. The overall results support a 'peaceful' model for reproductive immunology, in which elements of innate immunity have been incorporated in a constructive manner to support reproductive tissue development.     

Regenerative Xylem in Inflorescence Stems of <Emphasis Type="Italic">Arabidopsis thaliana</Emphasis>

By inserting entomological needles into the lower parts of young inflorescence stems of three-month-old Arabidopsis thaliana (L.) Heynh var. Colombia plants, we studied the process of regenerative xylem production. Regenerative xylem was formed only in one- to two-day-old inflorescence stems but not in older ones. The regenerative vessels originated from re-differentiation of cortical parenchyma. To characterize the process of regenerative xylem formation, we conducted a histological study from the time of wounding to day 30 after wounding. In the first day after wounding the tissues showed no structural responses except for the wounding itself. After six days, regenerative vessel members were already differentiating in a basipetal pattern, forming a vascular bypass around the wound. Regenerative vessel member formation reached a maximal level on the twelfth day after wounding. Sixteen days after wounding the pith parenchyma started to become loose as if indicating tissue senescence. Altogether, vascular regeneration following wounding in inflorescence stems of Arabidopsis thaliana is similar to that in other dicotyledon plants. These findings provide the basis for the use of Arabidopsis thaliana as a model system to study the genetics, physiology and cell biology of wound healing and regenerative vascular tissue formation.     

Complexes of HLA-G protein on the cell surface are important for leukocyte Ig-like receptor-1 function

The nonclassical class I MHC molecule HLA-G is selectively expressed on extravillous cytotrophoblast cells at the maternal-fetal interface during pregnancy. HLA-G can inhibit the killing mediated by NK cells via interaction with the inhibitory NK cell receptor, leukocyte Ig-like receptor-1 (LIR-1). Comparison of the sequence of the HLA-G molecule to other class I MHC proteins revealed two unique cysteine residues located in positions 42 and 147. Mutating these cysteine residues resulted in a dramatic decrease in LIR-1 Ig binding. Accordingly, the mutated HLA-G transfectants were less effective in the inhibition of NK killing and RBL/LIR-1 induced serotonin release. Immunoprecipitation experiments demonstrated the involvement of the cysteine residues in the formation of HLA-G protein oligomers on the cell surface. The cysteine residue located at position 42 is shown to be critical for the expression of such complexes. These oligomers, unique among the class I MHC proteins, probably bind to LIR-1 with increased avidity, resulting in an enhanced inhibitory function of LIR-1 and an impaired killing function of NK cells.     

Bark structure and mode of canopy regeneration in trees of Melia azedarach L.

Summary The bark texture of Melia azedarach L. changes from smooth to furrowed as trees age. In trees that were cut down, those with smooth bark sprouted below the cut from suppressed buds; trees with thick, furrowed bark sprouted at the edge of the cut surface from adventitious buds. The trees that had thin, furrowed bark sprouted mainly at the edge of the cut from adventitious buds, but sometimes also from suppressed buds in cracks. The relationship between sprouting pattern and tree architecture are discussed.     

Effects of transgene expression of superoxide dismutase and glutathione peroxidase on pulmonary epithelial cell growth in hyperoxia

Prolonged exposure to supraphysiological oxygen concentrations results in the generation of reactive oxygen species, which can cause significant lung injury in critically ill patients. Supplementation with human recombinant antioxidant enzymes (AOE) may mitigate hyperoxic lung injury, but it is unclear which combination and concentration will optimally protect pulmonary epithelial cells. First, stable cell lines were generated in alveolar epithelial cells (MLE12) overexpressing one or more of the following AOE: Mn superoxide dismutase (MnSOD), CuZnSOD, or glutathione peroxidase 1. Next, A549 cells were transduced with 50-300 particles/cell of recombinant adenovirus containing either LacZ or each of the three AOE (alone or in combination). Cells were then exposed to 95% O(2) for up to 3 days, with cell number and viability determined daily. Overexpression of either MnSOD (primarily mitochondrial) or CuZnSOD (primarily cytosolic) reversed the growth inhibitory effects of hyperoxia within the first 48 h of exposure, resulting in a significant increase in viable cells (P < 0.05), with 1.5- to 3-fold increases in activity providing optimal protection. Protection from mitochondrial oxidation was confirmed by assessing aconitase activity, which was significantly improved in cells overexpressing MnSOD (P < 0.05). Data indicate that optimal protection from hyperoxic injury occurs in cells coexpressing MnSOD and glutathione peroxidase 1, with prevention of mitochondrial oxidation being a critical factor. This has important implications for clinical trials in preterm infants receiving SOD supplementation to prevent acute and chronic lung injury.