A fine analysis of glucose-phosphate-isomerase patterns in single preimplantation mouse embryos

Mouse embryos were derived from eggs heterozygous for alleles of the dimeric enzyme glucose phosphate isomerase (Gpi-1a/Gpi-1b) that had been fertilized with sperm carrying a third allele (Gpi-1c). This particular combination makes it possible to study the activity of the paternally derived as well as the maternally derived genes, the persistence of oocyte-coded enzyme throughout early development and the possible simultaneous expression of both the paternally derived allele and the maternal message. The different isozymes present in single embryos were separated by electrophoresis. The results show that the oocyte-coded glucose phosphate isomerase is gradually replaced by embryo-coded enzyme. Expression of the paternally derived allele was first detected at the morula stage, during which the translation of the maternally derived message seemed to be either exhausted or below the detection limit of our system. Some oocyte-coded enzyme persisted until after implantation.     

Grouping of isolates in AG 2 ofRhizoctonia solani by total cellular fatty acid analysis

Total-cellular fatty acid compositions of 34 isolates ofRhizoctonia solani belonging to intraspecific groups (ISGs) of anastomosis group (AG) 2, i.e., AG 2-1, AG 2-2 IIIB (mat rush), AG 2-2 IV (sugar beet), AG 2-2 LP (turfgrass), and AG 2–3 (soybean), were compared. The major fatty acids identified were palmitic, stearic, and oleic acids. Principal component analysis based on the percentage composition of total cellular fatty acids revealed consistently low variability among isolates of a single ISG of AG 2. Average linkage cluster analysis showed that isolates obtained from turfgrass representing a newly proposed group, AG 2-2 LP, were differentiated from other AG 2 ISGs. Isolates of another newly proposed group AG 2–3, from diseased soybean were also closely related to AG 2-1 and AG 2-2 IIIB but distinguishable from the AG 2-1 and AG 2-2 LP isolates by the average linkage cluster analysis. These results suggested that the percentage composition of total-cellular fatty acids is a distinct characteristic for the five ISGs belonging to AG 2, and fatty acid analysis is useful for the differentiation and characterization of these ISGs of AG 2 inR. solani.