Problems encountered with the capillary tube immunodiffusion method for detection of botulinal toxin

By using antitoxin specific for the neurotoxin molecule, the capillary tube immunodiffusion method did not detect low levels of crystalline toxin. Reactions described earlier with crude toxin and less specific antitoxin were probably due to nontoxigenic botulinal antigens.     

Isolation of nucleoli and localization of ribonucleic Acid polymerase I from soybean hypocotyl

An effective method for the isolation of nucleoli from auxin-treated soybean (Glycine max, var. Wayne) hypocotyl was developed by polytron homogenization and sucrose gradient centrifugation. The nucleoli expressed only the α-amanitin-insensitive RNA synthetic activity. This activity chromatographed as RNA polymerase I on DEAE-cellulose. It appears that the plant nucleolus, like the animal nucleolus, is the site of localization for RNA polymerase I.     

Altered morphology in transgenic tobacco plants that overproduce cytokinins in specific tissues and organs.

An auxin-inducible bidirectional promoter from the soybean SAUR gene locus was fused to a reporter gene in one direction and a cytokinin biosynthetic gene in the opposite direction and the expression of these fused genes was examined in transgenic tobacco. The Escherichia coli uidA gene, which encodes the enzyme beta-glucuronidase (GUS), was used as the reporter gene and the Agrobacterium tumefaciens ipt gene, which encodes the enzyme isopentenyl transferase, was used as the cytokinin biosynthetic gene. These constructs allowed the overproduction of cytokinins in tobacco in a tissue- and organ-specific manner. Localized overproduction of cytokinins was monitored using the GUS reporter gene and measured by an ELISA assay. The tissue- and organ-specific overproduction of cytokinins produced a number of morphological and physiological changes, including stunting, loss of apical dominance, reduction in root initiation and growth, either acceleration or prolonged delayed senescence in leaves depending on the growth conditions, adventitious shoot formation from unwounded leaf veins and petioles, altered nutrient distribution, and abnormal tissue development in stems. While some of these morphological changes result directly from the localized overproduction of cytokinins, other changes probably result from the mobilization of plant nutrients to tissues rich in cytokinins.     

Direct fluorescence analysis of genetic polymorphisms by hybridization with oligonucleotide arrays on glass supports.

A simple and rapid method for the analysis of genetic polymorphisms has been developed using allele-specific oligonucleotide arrays bound to glass supports. Allele-specific oligonucleotides are covalently immobilized on glass slides in arrays of 3 mm spots. Genomic DNA is amplified by PCR using one fluorescently tagged primer oligonucleotide and one biotinylated primer oligonucleotide. The two complementary DNA strands are separated, the fluorescently tagged strand is hybridized to the support-bound oligonucleotide array, and the hybridization pattern is detected by fluorescence scanning. Multiple polymorphisms present in the PCR product may be detected in parallel. The effect of spacer length, surface density and hybridization conditions were evaluated, as was the relative efficacy of hybridization with single or double-stranded PCR products. The utility of the method was demonstrated in the parallel analysis of 5 point mutations from exon 4 of the human tyrosinase gene.     

The subunit structures of soluble and chromatin-bound RNA polymerase II from soybean

DNA-dependent RNA polymerase II is present in two forms, IIa and IIb, in germinating soybean. Form IIa is the dominant form of the enzyme in ungerminated embryos and appears to be a soluble enzyme. Form IIb increases in amount as germination progresses and is tightly bound to the chromatin template. The subunit structures of soybean RNA polymerases IIa and IIb are identical except for the molecular weights of their largest subunits which are 200,000 daltons and 170,000 daltons for IIa and IIb, respectively. The enzymes have seven common subunits: 142,000, 42,000, 26,000, 20,000, 16,000, 15,000, and 14,000 daltons.     

Osteoclasts recycle via osteomorphs during RANKL-stimulated bone resorption

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Design and applicability of DNA arrays and DNA barcodes in biodiversity monitoring

Background  

The rapid and accurate identification of species is a critical component of large-scale biodiversity monitoring programs. DNA arrays (micro and macro) and DNA barcodes are two molecular approaches that have recently garnered much attention. Here, we compare these two platforms for identification of an important group, the mammals.     

An auxin-induced polypeptide in dicotyledonous plants

Antisera were raised to a 70-kD (kilodalton) soybean (Glycine max) protein encoded by a 2,4-dichlorophenoxyacetic acid (2,4-D) inducible mRNA, GH3. These antisera have been used to probe protein blots to study the kinetics and specificity of the GH3 induction response as well as the species specificity and intracellular location of the protein. Detectable levels of the GH3 protein are induced by 2,4-D within 2 h in elongating hypocotyl sections, root sections, and etiolated plumules, and within 30–60 min in soybean suspension cells. Synthesis of the GH3 protein is induced by a variety of auxins. Other plant hormones such as gibberellic acid, cytokinin and ethylene added with or whithout 2,4-D do not alter the level of GH3 protein induction. The GH3 protein is found only in the S100 fraction and is not associated with the nucleus or cell wall. This antiserum also reacts with a 2,4-D-inducible 70-kD protein in other dicots.