A restricted human antitetanus clonotype shares idiotypic cross-reactivity with tetanus antibodies from most human donors and rabbits: reactivity with antibodies of widely differing electrophoretic mobility

Antitetanus antibodies from each of 20 hyperimmunized human donors were isolated on a tetanus immunoadsorbent, eluted with acidic buffer, and examined by isoelectric focusing (IEF). There was electrophoretic restriction, as determined by IEF, in the IgG of only 20% of the purified antibodies studied. The remaining 80% showed a more diffuse polyclonal spectrotype. Several IEF bands from the most electrophoretically restricted sample were isolated and used to immunize rabbits. Virtually every IgG-IEF band in the antitetanus antibodies of the original donor shared idiotypic cross-reactivity as detected by one or more of the three rabbit anti-Id reagents, even though major qualitative differences in binding from one rabbit anti-Id reagent to another were noted. Antitetanus antibodies of each of the 20 donors were separated by IEF and transferred to a nitrocellulose membrane. By using a sensitive and specific ELISA detection method, cross-reactivity was detected with the rabbit anti-Id reagents in 1 to 50% of the antitetanus antibodies of individual donors. This cross-reactivity was greater than 10% in 15 of the 19 antisera studied. In addition, these cross-reactive antibodies had very different electrophoretic mobility. Binding of the rabbit anti-Id reagents to the tetanus antibodies was almost completely blocked by pretreatment with soluble tetanus toxoid antigen. This idiotypic cross-reactivity with antibodies of different electrophoretic mobility from the same and unrelated donors suggests sharing among these antibodies of one or more of the germ-line DNA-encoded hypervariable regions present in the antibody-combining site.     

Binding of antibodies and other proteins to nitrocellulose in acidic, basic, and chaotropic buffers.

This report compares the binding of proteins to nitrocellulose membranes in acidic buffers (pH 2 and 3) with binding in neutral buffer (pH 7), basic buffers (pH 12 and 13), 8 M urea (pH 2, 3, and 7), and 6 M guanidine hydrochloride (pH unadjusted). Initially, similar amounts of antibodies and other proteins bound to the nitrocellulose membrane in all of these buffers and solvents. However, the susceptibility of individual proteins to displacement (stripping) from the membrane by the milk blocking agent depended on both the pH and the type of buffer or solvent used to bind the proteins to the membrane. Most proteins that were bound to nitrocellulose in acidic buffers were relatively resistant to milk stripping compared to proteins bound in pH 7 buffer. After correction for the amount of antibody remaining on the membrane after the milk block, it was found that acid-bound antibodies were unchanged in biological activity when compared with the same antibodies bound at neutral pH. These results suggest that acid binding of proteins could increase the sensitivity of nitrocellulose membrane assays using a milk block.     

Evidence of current impact of climate change on life: a walk from genes to the biosphere

We review the evidence of how organisms and populations are currently responding to climate change through phenotypic plasticity, genotypic evolution, changes in distribution and, in some cases, local extinction. Organisms alter their gene expression and metabolism to increase the concentrations of several antistress compounds and to change their physiology, phenology, growth and reproduction in response to climate change. Rapid adaptation and microevolution occur at the population level. Together with these phenotypic and genotypic adaptations, the movement of organisms and the turnover of populations can lead to migration toward habitats with better conditions unless hindered by barriers. Both migration and local extinction of populations have occurred. However, many unknowns for all these processes remain. The roles of phenotypic plasticity and genotypic evolution and their possible trade‐offs and links with population structure warrant further research. The application of omic techniques to ecological studies will greatly favor this research. It remains poorly understood how climate change will result in asymmetrical responses of species and how it will interact with other increasing global impacts, such as N eutrophication, changes in environmental N : P ratios and species invasion, among many others. The biogeochemical and biophysical feedbacks on climate of all these changes in vegetation are also poorly understood. We here review the evidence of responses to climate change and discuss the perspectives for increasing our knowledge of the interactions between climate change and life.     

Greater growth stability of trees in marginal habitats suggests a patchy pattern of population loss and retention in response to increased drought at the rear edge

Species rear range edges are predicted to retract as climate warms, yet evidence of population persistence is accumulating. Accounting for this disparity is essential to enable prediction and planning for species’ range retractions. At the Mediterranean edge of European beech‐dominated temperate forest, we tested the hypothesis that individual performance should decline at the limit of the species’ ecological tolerance in response to increased drought. We sampled 40 populations in a crossed factor design of geographical and ecological marginality and assessed tree growth resilience and decline in response to recent drought. Drought impacts occurred across the rear edge, but tree growth stability was unexpectedly high in geographically isolated marginal habitat and lower than anticipated in the species’ continuous range and better‐quality habitat. Our findings demonstrate that, at the rear edge, range shifts will be highly uneven and characterised by reduction in population density with local population retention rather than abrupt range retractions.     

Fatty acid regulation of liver X receptors (LXR) and peroxisome proliferator-activated receptor alpha (PPARalpha ) in HEK293 cells

Fatty acids bind to and regulate the activity of peroxisome proliferator-activated (PPAR) and liver X receptors (LXR). However, the role lipid metabolism plays in the control of intracellular fatty acid ligands is poorly understood. We have identified two strains of HEK293 cells that display differences in fatty acid regulation of nuclear receptors. Using full-length and Gal4-LBD chimeric receptors in functional assays, 20:4,n6 induced PPARalpha activity approximately 2.2-fold and suppressed LXRalpha activity by 80% (ED50 approximately 25-50 microm) in HEK293-E (early passage) cells but had no effect on PPARalpha or LXRalpha receptor activity in HEK293-L (late passage) cells. LXRbeta was insensitive to fatty acid regulation in both HEK293 strains. Metabolic labeling studies using [14C]20:4,n6 (at 100 microm) indicated that the uptake of 20:4,n6 and its assimilation into triacylglycerol, diacylglycerol, and polar lipids revealed no difference between the two strains. Such treatment increased total cellular 20:4,n6 ( approximately 11-fold) and its elongation product, 22:4,n6 ( approximately 3.6-fold), within 6 h. Non-esterified 20:4,n6 and 22:4,n6 represented 相似文献