Generation of floxed Spag6l mice and disruption of the gene by crossing to a Hprt-Cre line

Mouse sperm-associated antigen 6 like (SPAG6L) is an axoneme central apparatus protein, essential for the normal function of the ependymal cell and lung cilia, and sperm flagella. Accumulated evidence has disclosed multiple biological functions of SPAG6L, including ciliary/flagellar biogenesis and polarization, neurogenesis, and neuronal migration. Conventional Spag6l knockout mice died of hydrocephalus, which impedes further investigation of the function of the gene in vivo. To overcome the limitation of the short lifespan of conventional knockout mice, we developed a conditional allele by inserting two loxP sites in the genome flanking exon 3 of the Spag6l gene. By crossing the floxed Spag6l mice to a Hrpt-Cre line which expresses Cre recombinase ubiquitously in vivo, mutant mice that are missing SPAG6L globally were obtained. Homozygous mutant Spag6l mice showed normal appearance within the first week after birth, but reduced body size was observed after 1 week, and all developed hydrocephalus and died within 4 weeks of age. The phenotype mirrored that of the conventional Spag6l knockout mice. The newly established floxed Spag6l model provides a powerful tool to further investigate the role of the Spag6l gene in individual cell types and tissues.     

Age-related changes in albumin elimination in female WAG/Rij rats.

Albumin elimination rates were determined in 3-, 12-, 24- and 36-month-old female WAG/Rij rats. No change in elimination half-life was found with age. However, as there was an increase in the whole-body albumin pool, a concomitant increase in albumin clearance was observed at between 12 and 36 months of age. It was concluded that the increase in clearance between 12 and 24 months of age was only due to a change in the animal's physiology, whereas between 24 and 36 months of age it was also due to changes in the albumin molecule. The age-related changes in albumin clearance were thought not to be caused by changes in the albumin excretion via the urine or via the gastrointestinal tract.     

Taenia hydatigena: isolation of mitochondrial DNA, molecular cloning, and physical mitochondrial genome mapping

Mitochondrial DNA was isolated from Taenia hydatigena, T. crassiceps, and Echinococcus granulosus using a cetyltrimethylammonium bromide precipitation technique. The technique is simple, rapid, reproducible, and does not require extensive high speed ultracentrifugation. The advantage of using mitochondrial DNA from taeniid cestodes for comparative restriction analysis was demonstrated. Mitochondrial DNA of T. hydatigena was isolated as covalently closed circular molecules. These were linearized by single digestion with BamHI and the molecular weight was estimated from the linear form of 17.6 kb. The mitochondrial DNA of T. hydatigena is therefore similar in size and structure to that of many other animal species. The entire mitochondrial genome was cloned into pBR322 in Escherichia coli and a restriction map of the recombinant molecule was constructed. The potential of using the cloned mitochondrial genome as a probe in speciation studies as well as for providing functional information on the role of the cestode mitochondrion is discussed.