Genetic control of Endosperm Balance Number (EBN) in the Solanaceae based on trisomic and mutation analysis.

The genetic control of Endosperm Balance Number (EBN) was studied using trisomics and induced mutation. In order to induce and detect a change in a factor determining the EBN of the male, pollen from tetraploid Datura was irradiated and used to pollinate diploids. No triploids were produced in over 70 000 fertilizations. At least 70 would have been expected if the deletion of the function of a single gene could change the EBN. An attempt was made to find a particular chromosome that could alter the EBN of the female when it was present as the extra chromosome in 2x + 1 x 4x crosses. In tests of trisomics in both Datura and Solanum (potato) no chromosome could be found that changed the EBN. Therefore, it is concluded that more than one gene and more than one chromosome is involved in determining EBN. Key words : crossing barriers, endosperm, Datura, potato, speciation.     

A protocol for the efficient screening of putatively transformed plants forbar,the selectable marker gene,using the polymerase chain reaction

Amplification of thebar gene usingTaq DNA polymerase in PCR is often not successful, possibly due tobar's high GC content. We describe a PCR protocol in which reliable amplification at a sensitivity of one gene copy per genome (in this study, barley) present in the reaction was achieved using a novel pair of primers and Expand^tm High Fidelity DNA polymerase mix (Boehringer Mannheim). This method should allow for rapid screening of plants putatively transformed withbar.     

Expression and purification strategies for the production of single-chain antibody and T-cell receptor fragments inE. coli

This work describes protocols for the production of single-chain antibody and T-cell receptor fragments inE. coli. A choice of methods is given for the purification of the recombinant fragments that rely on the use of either immunoaffinity or metal chelate affinity chromatography. The TCR fragments may have to be denatured and refolded before the fragments attain their proper conformation.     

Epr Studies on the Effects of Complexation of Heme by Hemopexin upon its Reactions with Organic Peroxides

Hemopexin, a heme-binding serum glycoprotein, is thought to play an important role in the prevention of oxidative damage that may be catalysed by free heme. Through the use of EPR techniques, the generation of free radicals from organic hydroperoxides by heme and heme-hemopexin complexes, and the concomitant formation of high oxidation-state iron species has been studied; these species are implicated as causative agents in processes such as cardiovascular disease and carcinogenesis. From the rates of production of these species from both n-alkyl and branched hydroperoxides, it has been inferred that the dramatic reduction in the yield of oxidising species generated by heme upon its complexation with hemopexin arises from steric hindrance of the access of hydroperoxide to the bound heme.     

Individual Odors in Djungarian Hamsters (Phodopus campbelli)

The sources of scent in Djungarian hamsters (Phodopus campbelli) that may be individually discriminated were investigated using an habituation paradigm. Male Djungarian hamsters were exposed to five presentations of a particular scent from one individual, and then to the same scent from a novel individual. Increased investigation of the scent from the novel individual indicated discrimination of scents from different individuals. Male hamsters distinguished individual differences in scents of other males from the midventral gland, urine, feces, mouth, and the corner of the mouth, which includes the sacculi; they did not discriminate among odors of different individuals when the scents were from the genital region, hindfeet, fur from behind ears or fur from the back. The results indicate that Djungarian hamsters have a repertoire of individually distinctive scents that are located in specific places on the body; these scents are not actively distributed to, nor passively picked up on, other parts of the body. The fact that scents from some areas do not contain individually distinctive information suggests that some sources may be specialized for producing individually distinctive scents.