Somatomedin-C in the kidney of streptozotocin diabetic rats

To evaluate the possible role of somatomedin-C, insulin-like growth factor I, in renal hypertrophy in early diabetes, kidney tissue SmC concentrations were measured in streptozotocin-induced (80 mg/kg ip) diabetic rats. Body weight, liver weight, plasma SmC concentration, and SmC concentration in the liver of diabetic rats were significantly lower than those of controls. Seven days after induction of diabetes, the kidney weight (898 +/- 95 mg) in diabetic rats was significantly greater than that in controls (755 +/- 69 mg), while SmC concentration in the kidney of diabetic rats (1.7 +/- 0.3 U/g kidney) was significantly lower than that of control rats (5.4 +/- 0.6 U/g kidney). These results suggest that renal SmC may not have an important role in renal hypertrophy in early stages of diabetes and that renal production of SmC may be impaired by insulin deficiency in rats.     

Evidence for the location of foreign genes in three different chromosomes in a plant obtained from direct DNA transfer

Tobacco mesophyll protoplasts were treated with plasmids, pCT2 (17.1 kbp) or pCT2T3 (18.3 kbp), which contained a chimeric aminoglycoside phosphotransferase II (APH(3′)II) gene and an intact nopaline synthase gene. Expression of two marker enzymes, APH(3′)II and nopaline synthase, were analyzed in transformed plants. Four out of 16 transformants obtained by pCT2T3 possessed both enzymes. Upon self-pollination, the progeny of one of transformants (T2) segregated to 153∶4 in terms of resistant and susceptible character to kanamycin, suggesting insertion of foreign genes into three independent chromosomes. The kanamycin resistant character in the rest of transformants showed 3∶1 segregation. DNA blot analysis of the T2 transformant and progenies indicated the presence of two marker genes.     

Comparative study of embryonic thermoresistance of two inbred strains of the medaka (Oryzias latipes)

Summary By using inbred strains (HO4C and HB32C) of the medaka,Oryzias latipes, the involvement of genetic factor(s) in the determination of thermoresistance of fish was investigated. The thermoresistance of embryos of the medaka was quantitated by the fraction of the embryos surviving 1 day after heat treatment. At early stages of development (st. 13 and st. 20–21), the HO4C strain was more resistant than the HB32C strain. At st. 20–21, the HO4C strain was more resistant than the HB32C strain at all temperatures used (42, 43, and 44°C). At later stages of development (st. 27 and st. 32), however, the HB32C strain was more resistant than the HO4C strain.The results of genetic cross experiments raised the following possibilities; the thermoresistance of embryos at early developmental stages can be lowered by some factor(s) inherited in the HO4C strain and/or increased by those in the HB32C strain. By contrast, the sensitivity of embryos at later stages of development was not affected by factor(s) of their parents, but by their own genetic constitution.     

Phosphorylation of Delta Sleep-Inducing Peptide (DSIP) by casein kinase II in vitro

A phosphorylated analogue of DSIP at Ser⁷ has been shown to exist endogenously by immunochemical studies. An enzyme which could phosphorylate DSIP has not yet been identified. In the present study, we examined DSIP as a substrate for in vitro phosphorylation by casein kinase II. DSIP was phosphorylated by the enzyme with apparent K_m and V_max values of 20 mM and 90.9 nmol/min/mg protein, respectively. Both ATP and GTP were utilized as phosphoryl donors. Phosphorylation of DSIP was inhibited by heparin and enhanced by spermine. These results demonstrate that DSIP can serve as a possible substrate for casein kinase II in vitro.