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The pckA gene, encoding the gluconeogenic enzyme phosphoenolpyruvate carboxykinase (PEPCK), was cloned by PCR amplification from the purple nonsulfur bacterium Rhodopseudomonas palustris No. 7. Sequencing of a 2.5-kb chromosomal Sma I- Pst I fragment containing the structural gene revealed an open reading frame encoding 537 amino acids, homologous to known pckA genes. Primer extension analysis identified a transcriptional start site 72 bp upstream of the pckA initiation codon and an upstream sequence similar to ς 70 promoters. Studies of a pckA-lacZ gene fusion indicated that when cells were grown in minimal media with various carbon sources, such as succinate, malate, pyruvate, lactate, or ethanol, under both anaerobic light and aerobic dark conditions, the pckA gene was induced in log phase, irrespective of the carbon source. A R. palustris No. 7 PEPCK-deficient strain showed growth characteristics identical to those of the wild-type strain either anaerobically in the light or aerobically in the dark when a C 4 -dicarboxylic acid, such as succinate or malate, was used as a carbon source. These results indicate that in R. palustris No. 7, an alternative gluconeogenic pathway may exist in addition to PEPCK.

Androgen is closely involved as the cause of rupture of anterior cruciate ligament (ACL) in human. In dogs, however, factors contributing to rupture of ACL remain unknown. In this study, expression of androgen receptor (AR) and histological distribution of blood vessels in ACL, and serum testosterone concentration were investigated in relation with age and sex to confirm whether canine ACL is an androgen-responsive tissue. Materials of ACL were obtained from 26 dogs: 12 young female Beagles, 2 old female mixed breeds, 9 young male Beagles, and 3 old male mixed breeds. In all canine ACL, positive AR expression was recognized in the nuclei of the fibrocytes, fibroblasts, synovial cells, and vascular endothelial cells of ACL. Expressions of AR were lesser in old males compared to the young males; however, females had no age difference in expression. Distributions of blood vessels in the synovial membrane of the ligament were fewer in old dogs both of males and females than youngs. Although distributions of vessels in the interstitium were apparently fewer in young females. Serum testosterone concentration was significantly higher in young males. Females had no age difference in the levels. From these results, it is suggested that canine ACL is an androgen-responsive tissue, and this consideration seems to closely relate to the epidemiological background that the incidence of rupture of ACL of dogs is higher in females than in males.