Enzyme immunoassay for plasma 25-hydroxyvitamin D3 employing immunoaffinity chromatography as a pretreatment method

Loss of obligate crossovers, defective cytokinesis and male sterility in barley caused by short-term heat stress

Short-term heat stress during male meiosis causes defects in crossover formation, meiotic progression and cell wall formation in the monocot barley, ultimately leading to pollen abortion. High temperature conditions cause a reduction of fertility due to alterations in meiotic processes and gametogenesis. The male gametophyte development has been shown to be particularly sensitive to heat stress, and even short-term and modest temperature shifts cause alterations in crossover formation. In line with previous reports, we observed that male meiosis in the monocot barley exposed for 24-45 h to heat stress (32-42 °C) partially or completely eliminates obligate crossover formation and causes unbalanced chromosome segregation and meiotic abortion. Depending on the severity of heat stress, the structure and organization of the chromosomes were altered. In addition to alterations in chromosome structure and dynamics, heat treatment abolished or reduced the formation of a callose wall surrounding the meiocytes and interrupted the cell cycle progression leading to cytokinesis defects and microspore cell death.

Immunochemical monitoring of psilocybin and psilocin to identify hallucinogenic mushrooms

Development of rapid and reliable immunochemical methods for monitoring psilocybin (4-phosphoryloxy-N,N-dimethyltryptamine; Pyb) and psilocin (dephosphorylated metabolite; Psi), the psychoactive compounds contained within hallucinogenic mushrooms (magic mushrooms), is desirable in order to identify these mushrooms and regulate their illicit use. Because no antibody was publicly available for this purpose, we generated two independent monoclonal antibodies (mAbs) against Pyb or Psi, and then developed enzyme-linked immunosorbent assays (ELISAs) by using them. To generate the specific antibodies, novel immunogenic conjugates were prepared by linking Pyb or Psi molecules to carrier proteins by modifying their 2-(N,N-dimethylamino)ethyl side chains. Spleen cells from mice immunized with these conjugates were fused with P3/NS1/1-Ag4-1 myeloma cells, and hybridoma clones secreting anti-Pyb and anti-Psi mAbs were established. These mAbs were characterized for their biochemical features and then applied to competitive ELISAs, which used microplates coated with Pyb or Psi linked with albumin. These ELISAs enabled the determination of Pyb or Psi with measurable ranges of ca. 0.20-20 or 0.040-2.0 μg/assay (limit of detection was 0.14 or 0.029 μg/assay), respectively. The related tryptamines were satisfactorily discriminated as exemplified by the cross-reactivity of the ELISA to determine Pyb (or Psi) with Psi (or Pyb) that were found to be 2.8 % (or <0.5 %), respectively. The Pyb and Psi contents in a dried powder of the hallucinogenic mushroom, Psilocybe cubensis, were determined to be 0.39 and 0.32 (w/w)%, respectively. The ELISAs developed using the current mAbs are promising tools for identifying illegal hallucinogenic mushrooms.

Production and characterization of monoclonal antibodies against a novel 1alpha,25-dihydroxyvitamin D3-bovine serum albumin conjugate linked through the 11alpha-position

To obtain an antibody which is useful for developing a selective immunoaffinity chromatography (IAC) of 1alpha,25-dihydroxyvitamin D3 [1,25(OH)2D3], which is an effective pretreatment tool for determining this metabolite in biological fluids, a variety of monoclonal antibodies have been produced against a novel haptenic derivative, 11alpha-hemiglutaryloxy-1alpha,25-dihydroxyvitamin D3, linked to bovine serum albumin. BALB/c, A/J and C57BL/6 mice, as well as Wistar and SD rats, were immunized with the hapten-carrier conjugate and the titer of the anti-1,25(OH)2D3 antibody in serum was examined. Spleen cells from A/J mice or SD rats, which showed a high titer, were fused with P3/NS1/1-Ag4-1 myeloma cells. After serial screening by enzyme-linked immunosorbent assay and radioimmunoassay, sixteen kinds of hybridoma clones secreting different anti-1,25(OH)2D3 antibodies were established. Scatchard analysis revealed that 12 antibodies out of 16 have enough affinity to 1,25(OH)2D3 (Ka>10(9) M[-1]). By a cross-reaction study using various related compounds, two antibodies, M114 and M129, both derived from A/J mice, were found to have suitable specificity. Although they showed relatively high cross-reactivities with the 1,25(OH)2D3 derivatives having 24-hydroxylated (both 20%) or lactonized (30%, 8.9%) side chain, all the tested 1alpha-deoxy-type metabolites, some of which interfere with the 1,25(OH)2D3 assays, were successfully discriminated [25(OH)D3: 0.67%, 0.40%; 24,25(OH)2D3: 0.27%, 0.24%; 25(OH)D3 3-sulfate: 0.11%, 0.14%]. These monoclonal antibodies will be applicable for developing not only IAC but also various immunoassay procedures.

Tandem immunoaffinity chromatography for plasma 1 alpha,25-dihydroxyvitamin D3 utilizing two antibodies having different specificities: a novel and powerful pretreatment tool for 1 alpha,25-dihydroxyvitamin D3 radioreceptor assays

We report here a novel and powerful pretreatment method for radioreceptor assays (RRAs) for human plasma 1 alpha,25-dihydroxyvitamin D3 (1,25(OH)2D3) based on "Tandem" immunoaffinity chromatography (Tandem IAC). Two antibodies having different specificities were each immobilized on agarose gel with cyanogen bromide to produce immunosorbents which were stable and repeatedly usable. An ethyl ether extract of plasma was applied to the first affinity column, from which 1,25(OH)2D3 could be preferentially eluted and separated from 1 alpha-deoxy type metabolites. The effluent was then submitted to the second column, and the 1,25(OH)2D3 retained was eluted after non- or weakly-absorbed interfering substances were washed out. This procedure allowed efficient purification without careful handling or strict time-management in the entire operation and enabled avoiding preparative high-performance liquid chromatography (HPLC) from RRA even with a conventional chick intestinal vitamin D receptor. Mean (+/- SD) plasma 1,25(OH)2D3 values of 56 normal subjects and 10 patients with chronic renal failure, obtained with this Tandem IAC/RRA system, were 36.4 (8.7) and 11.2 (4.0) pg/ml, respectively. The Tandem IAC will also be useful for developing immunoassays or gas chromatography-mass spectrometry of 1,25(OH)2D3.

Specificity of the polyclonal antibodies raised against a novel 25-hydroxyvitamin D3-bovine serum albumin conjugate linked through the C-11 alpha position

To obtain a specific antibody for use in 25-hydroxyvitamin D3 [25(OH)D3] immunoassay, a novel hapten-carrier conjugate was prepared by coupling 11 alpha-hemiglutaryloxy-25(OH)D3 with bovine serum albumin (BSA). Three polyclonal antibodies (Ab11) showing high titer and affinity for 25(OH)D3 (Ka = 0.96-2.6 x 10(9) M-1) were elicited in rabbits by repeated immunization with the conjugate. Specificity of the Ab11 was investigated by cross-reactivities with 11 related compounds in a radioimmunoassay using a tritium-labeled antigen and compared with that of conventional antibodies (Ab3) raised against 25(OH)D3 3-hemiglutarate conjugated with BSA. The Ab3 could not discriminate the A-ring modified metabolites [1,25(OH)2D3 (87-290%) and 25(OH)D3 3-sulfate (S) (130-180%)], although the cross-reactivities with the side chain modified metabolites were satisfactorily low [24,25(OH)2D3 (2.3-7.4%), 25(OH)D2 (< or = 1.1%)]. On the contrary, the Ab11 easily discriminated 1,25(OH)2D3 (0.10-2.4%) and 25(OH)D3 3S (< 0.3%), whereas significant cross-reactivities were found with 24,25(OH)2D3 (110-120%) and 25,26(OH)2D3 (66-130%) having a dihydroxylated side chain. These results show that the Ab11 are complementary to the A-ring portion of the 25(OH)D3 molecule which is opposite from the side chain structure recognized by the Ab3. Thus, the Ab11 will compensate for insufficient specificity of the Ab3 and are expected to be a useful tool for the pretreatment of biological samples in the development of various analyses of vitamin D metabolites including specific 25(OH)D3 immunoassays using the Ab3.