Age-specific responses to climate identified in the growth of Quercus alba

The objective of this research was to determine whether the dendroclimatic responses of young Quercus alba (aged 29–126 years) differ from those of old Q. alba (149–312 years). We collected Q. alba increment cores across a range of size classes from Buffalo Mountain Natural Area Preserve, an oak-hickory forest in southcentral Virginia, USA. Tree cores were crossdated and raw ring widths were detrended to remove the influence of increasing circumference with age, microsite, and local stand dynamics. Standardized ring widths were averaged to develop two master chronologies from the 20 oldest and youngest trees. Ring-width indices were correlated with temperature, precipitation, and Palmer Drought Severity Index (PDSI). Annual tree-ring growth in old and young Q. alba was significantly correlated with precipitation from the previous growing season, but was not significantly correlated with temperature. Only the old trees showed a significant correlation between annual ring width and PDSI. These results may indicate that growth in old trees is more sensitive to drought than in young trees. If future climate change includes the predicted increase in mid-growing season droughts, tree-level responses are likely to be age-dependent with older trees experiencing relatively greater reductions in growth.     

Novel splice variants derived from the receptor tyrosine kinase superfamily are potential therapeutics for rheumatoid arthritis

Introduction  

Despite the advent of biological therapies for the treatment of rheumatoid arthritis, there is a compelling need to develop alternative therapeutic targets for nonresponders to existing treatments. Soluble receptors occur naturally in vivo, such as the splice variant of the cell surface receptor for vascular endothelial growth factor (VEGF) – a key regulator of angiogenesis in rheumatoid arthritis. Bioinformatics analyses predict that the majority of human genes undergo alternative splicing, generating proteins – many of which may have regulatory functions. The objective of the present study was to identify alternative splice variants (ASV) from cell surface receptor genes, and to determine whether the novel proteins encoded exert therapeutic activity in an in vivo model of arthritis.     

The international society for plant anaerobiosis and its role in opening a new avenue of research

This paper is dedicated to the 35 year jubilee of the founding and the activity of the International Society for Plant Anaerobiosis (ISPA). The role of ISPA members in opening new avenues of research is emphasized. Major developments in the study of plant hypoxic and anoxic stress achieved during subsequent decades are considered. Special attention is given to plant adaptation and damage under conditions of oxygen deficiency and complete absence of oxygen as well as during the post-anaerobic period. Plant metabolic adaptation to anaerobic stress and the capacity of some plants to avoid anaerobiosis are discussed.     

The nature of plant growth-promoting effects of a pseudoalteromonad associated with the marine algae Laminaria japonica and linked to catalase excretion

AIMS: The goal of this study was to identify a marine algae-associated bacterium isolated from Laminaria japonica and investigate this microorganism's growth-promoting effects on plants. METHODS AND RESULTS: The bacterium, identified as Pseudoalteromonas porphyrae, was determined to display a biostimulatory activity for seed germination and shoot growth in several agricultural plants and also for growth in ginseng callus cell culture. This biostimulatory activity was linked to a catalase enzyme that was excreted in the maximal amount during the transition from logarithmic growth phase to stationary growth phase. In addition, selected shifts in growth temperature and medium salinity affected the amount of enzyme excreted. The purified catalase was determined to be composed of identical subunits. The catalase of interest displayed significantly higher biostimulatory activity than the catalase from bovine liver. CONCLUSIONS: The catalase investigated in this study is unique in that it promotes growth in and possibly contributes to stress tolerance of plants. SIGNIFICANCE AND IMPACT OF THE STUDY: The catalase of interest has the potential for use in treatments that aim to improve percent seed germination as well as obtaining tall shoots in a shorter time period.     

Differential selection pressure exerted on HIV by CTL targeting identical epitopes but restricted by distinct HLA alleles from the same HLA supertype

HLA diversity is seen as a major challenge to CTL vaccines against HIV. One current approach focuses on "promiscuous" epitopes, presented by multiple HLA alleles from within the same HLA supertype. However, the effectiveness of such supertype vaccines depends upon the functional equivalence of CTL targeting a particular epitope, irrespective of the restricting HLA. In this study, we describe the promiscuous HIV-specific CTL epitopes presented by alleles within the B7 supertype. Substantial differences were observed in the ability of CTL to select for escape mutation when targeting the same epitope but restricted by different HLA. This observation was common to all six promiscuous B7 epitopes identified. Moreover, with one exception, there were no significant differences in the frequency, magnitude, or immunodominance of the CTL responses restricted by different HLA alleles to explain these discrepancies. This suggests that the unique peptide/MHC complexes generated by even closely related HLA induce CTL responses that are qualitatively different. This hypothesis is supported by additional differences observed between CTL targeting identical epitopes but restricted by different HLA: first, the occurrence of distinct, HLA-specific escape mutation; second, the recruitment of distinct TCR repertoires by particular peptide/MHC complexes; and, third, significant differences in the functional avidity of CTL. Taken together, these data indicate that significant functional differences exist between CTL targeting identical epitopes but restricted by different, albeit closely related HLA. These findings are of relevance to vaccine approaches that seek to exploit HLA supertypes to overcome the problem of HLA diversity.     

In vitro development of the hamster and chick secondary palate

A series of experiments were undertaken to compare the in vitro behaviour of the medial edge epithelium (MEE) of hamster, in which palatal shelves normally fuse, and chick, in which they do not fuse. Homotypic pairs of hamster and chick embryo palatal processes, single palatal processes, and heterotypic palatal shelves of both animals were grown in vitro. The results indicated that contact between palatal shelves may not be crucial for MEE differentiation in mammals. The ability to acquire pre-fusion characteristics may be present in mammalian palatal tissue from their early development and may be expressed by cessation of DNA synthesis in the MEE, elevation of cAMP, and MEE cell death. Isolated chick palatal shelf cultured under identical conditions did not express these mammalian pre-fusion characteristics. When MEE of hamster and chick palatal shelves were placed in contact with one another, the intervening epithelia underwent cytolysis. This could be due to either the destruction of chick MEE by lysosomal enzymes liberated from adjacent degenerating hamster MEE cells, or by induction of cell death in chick MEE by hamster mesenchyme. Heterotypic palatal tissue combinations also suggest that release of lysosomal enzymes in the hamster MEE, which leads to its dissolution, may be the terminal event in epithelial differentiation prior to the establishment of mesenchymal continuity. It is suggested that an inverse relationship exists between DNA synthesis and cAMP levels during palatogenesis: when palate closes (as in mammals) the MEE is eliminated by increasing cAMP levels, whereas when palate remains open (as in birds) low level of cAMP preserve the integrity of MEE by supporting DNA synthesis.     

How to Make a Rodent Giant: Genomic Basis and Tradeoffs of Gigantism in the Capybara,the World’s Largest Rodent

Gigantism results when one lineage within a clade evolves extremely large body size relative to its small-bodied ancestors, a common phenomenon in animals. Theory predicts that the evolution of giants should be constrained by two tradeoffs. First, because body size is negatively correlated with population size, purifying selection is expected to be less efficient in species of large body size, leading to increased mutational load. Second, gigantism is achieved through generating a higher number of cells along with higher rates of cell proliferation, thus increasing the likelihood of cancer. To explore the genetic basis of gigantism in rodents and uncover genomic signatures of gigantism-related tradeoffs, we assembled a draft genome of the capybara (Hydrochoerus hydrochaeris), the world’s largest living rodent. We found that the genome-wide ratio of nonsynonymous to synonymous mutations (ω) is elevated in the capybara relative to other rodents, likely caused by a generation-time effect and consistent with a nearly neutral model of molecular evolution. A genome-wide scan for adaptive protein evolution in the capybara highlighted several genes controlling postnatal bone growth regulation and musculoskeletal development, which are relevant to anatomical and developmental modifications for an increase in overall body size. Capybara-specific gene-family expansions included a putative novel anticancer adaptation that involves T-cell-mediated tumor suppression, offering a potential resolution to the increased cancer risk in this lineage. Our comparative genomic results uncovered the signature of an intragenomic conflict where the evolution of gigantism in the capybara involved selection on genes and pathways that are directly linked to cancer.     

A sensitive procedure for quantifying the phagocytic competence of blood granulocytes

The phagocytic activity of blood granulocytes can be quantitatively assayed by ingestion of opsonised paraffin oil droplets containing the dye Oil Red-O (Stossel, T. P., Mason, R. J., Hartwig, J., and Vaughan, M. (1972)J. Clin. Invest. 51:615–624). We have modified this assay by incorporating [³H]glycerol into the oil droplets which allows a more sensitive and reproducible measurement of the phagocytic competence of blood granulocytes even at very low cell counts. Comparative studies after one day storage of the blood at 4°C is feasible since they retain 84 % of the phagocytic capacity measured when isolated from fresh blood.     

Okanin 4′-O-diglucoside from Coreopsis petrophiloides and comments on anthochlors and evolution in Coreopsis

A new chalcone glycoside, okanin 4′-O-diglucoside, is identified from the ray florets of Coreopsis petrophiloides. The known distribution of anthochlors in Coreopsis indicates that two of the most primitive sections produce in their floral parts complex glucosides of butein (and sulfuretin). The more advanced sections synthesize the monoglucosides of okanin (marein), butein (coreospin) and lanceoletin (lanceolin) and their corresponding aurones. The co-occurrence of marein and lanceolin is thus far restricted to members of sect. Coreopsis.