Binding proteins, thought to be auxin receptors, can be solubilised from maize (Zea mays L.) membranes after acetone treatment. From these crude extracts, receptor preparations of over 50% purity can be obtained by a reliable, straight-forward procedure involving three chromatographic steps - anion exchange, gel filtration and high-resolution anion exchange. Such preparations have been used to immunise rats for subsequent production of monoclonal antibodies. By the further step of native polyacrylamide gel electrophoresis the semi-purified preparations yield homogeneous, dimeric (22-kilodalton, kDa) auxin-binding protein, which has been used to produce a polyclonal rabbit antiserum. The preliminary characterisation of this antiserum and of the five monoclonal antibodies is presented. Two of the monoclonal antibodies specifically recognise the major 22-kDa-binding protein polypeptide whilst the other three recognise, in addition, a minor 21-kDa species. All the monoclonal antibodies recognise the polypeptide rather than the glycan side chain and the polyclonal antiserum also recognises deglycosylated binding protein. The antibodies have been used to quantify the abundance of auxinbinding protein in a number of tissues of etiolated maize seedlings. Root membranes contain 20-fold less binding protein than coleoptile membranes.

Articles you may be interested inTwo-photon-excited fluorescence resonance energy transfer in an aqueous system of CdTe quantum dots and Rhodamine BNew polarized time resolved fluorescence techniques are implemented to determine the full angular motion of a probe molecule in an anisotropic environment. Studies of rhodamine 6G and resorufin molecules aligned in a free ethylene glycol jet show that the presence of net molecular order is accompanied by a distinct anisotropy in alignment relaxation following photoselection. Diffusion coefficients for and motion ͑D ʈ and D Ќ ͒ in a jet fixed axis system are determined from the cylindrically symmetric and asymmetric alignment relaxation rates for the isotropic and anisotropic regions of the jet. The presence of net negative molecular alignment as the free jet is formed is seen to correspond to restricted motion (D ʈ ϽD Ќ ), with a net positive steady state alignment the anisotropy in the diffusion dynamics is reversed. The differences in D ʈ and D Ќ are attributed to anisotropy in the solvent viscosity as a consequence of flow. The combination of linear and circular polarization techniques is seen to provide useful information on cylindrical asymmetry and relaxation dynamics hitherto unobserved by conventional fluorescence polarization techniques.

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Currently, the only successful method for separating X and Y chromosome-bearing spermatozoa is fluorescence-activated cell sorting. Although effective, this technique is of limited usefulness to the animal breeding industry as it cannot produce the large volumes of sexed spermatozoa needed for artificial insemination. An attractive alternative would be to identify an immunological marker confined to one sperm type and, therefore, significant scientific effort has been expended in examining antibodies that appear to recognize approximately 50% of spermatozoa in an ejaculate. However, no sex-specific antigens have yet been identified from spermatozoa. Using the opportunity afforded by the development of sperm separation by fluorescence-activated cell sorting, we have made a thorough search for differences between X and Y chromosome-bearing bull spermatozoa using both biochemical and immunological methods. Techniques for radiolabelling surface membrane proteins, in conjunction with SDS-PAGE, failed to show any differences between populations. Similarly, a wide range of monoclonal antibodies raised to ejaculated, cauda epididymidal and testicular spermatozoa failed to distinguish between the X and Y chromosome-bearing spermatozoa. Only after analysis by high resolution two-dimensional SDS-PAGE was an indication obtained that X-specific proteins occur. However, these proteins are not associated with the surface membrane and further work is necessary to confirm their association with the X chromosome and to characterize them more fully. Our inability to detect sex-specific differences in sperm surface antigenicity suggests that further work on this immunological approach to semen sexing is unlikely to be profitable.

From a single aflatoxin B1 oxime - bovine serum albumin conjugate, polyclonal and monoclonal antibody preparations were produced. The four rabbit polyclonal antisera were specific for aflatoxin Bi in a microtitration plate enzyme - linked immunosorbent assay. The monoclonal antibodies showed a wide range of differing specificities, recognizing, for example, aflatoxins B1, B2, G1 and G2; B1 and B2; B1 and G1; and G1 alone. No antibody preparations reacted with aflatoxin M1. The significance of these results to the strategy of anti-aflatoxin antibody production for use in quantitative enzyme immunoassays is discussed.