Hybrid dysgenesis in natural populations of Drosophila melanogaster in Japan. III. The P-M system in and around Japan.

The P-M system of hybrid dysgenesis in Drosophila melanogaster was investigated on the basis of gonadal dysgenesis, using 1,590 strains from 28 natural populations in Japan, and 20 populations from Southeast Asia, the Pacific area and Africa. Strong P strains were found sporadically in several populations in Japan. Few strong M strains were observed. Q strains were present at a high frequency in most populations. Thus, most populations in these areas were regarded as Q populations. The distribution of the P element and the evolution of P, Q and M populations are also discussed.

The necessity of dietary vitamin B6 to selenium biopotency for tissue selenium and glutathione peroxidase in rats.

Necessity of dietary vitamin B6 to the biopotency of selenium (Se) for the levels of Se and glutathione peroxidase (GSH-Px) in tissues was investigated. Male Wistar 12-week-old rats were fed a vitamin B6-Se-deficient basal diet for 3 weeks, and then the rats were divided into 6 groups. One group was fed the basal diet, the others were fed the diet supplemented with 250 micrograms vitamin B6/100 g as pyridoxine.HCl, or 0.25 mg Se/kg as Na2SeO3 (SeL) or DL-selenomethionine (Se-Met), or both (SeL+B6 or Se-Met+B6) for 10 week. The levels of Se and GSH-Px in erythrocytes and muscle were significantly higher in vitamin B6-supplemented groups than in vitamin B6-deficient groups. There was little effect of this vitamin deficiency on Se level in liver of rats fed SeL; however, a higher Se level in liver was observed in vitamin B6-deficient rats fed Se-Met than in the corresponding B6-supplemented rats. A significant decrease of GSH-Px activity in liver was found in vitamin B6-deficient animals fed Se-Met compared with vitamin B6-supplemented animals, whereas no significant decrease was observed in those fed SeL. These results suggest that this vitamin is involved in the transport and deliverance of Se in plasma to the other tissues and the incorporation of Se from Se-Met to GSH-Px in liver.

Fatty acid composition of breast milk from Nigerian and Japanese women.

The fatty acid composition of samples of breast milk obtained from well-nourished Nigerian and Japanese women was determined by gas chromatography. The cultural differences in dietary intake was reflected in the fatty acid composition of breast milk samples. The milk of Nigerian women contained a significantly higher percentage of saturated fatty acids (48.75%) than that of Japanese women (46.65%). Nigerian milks were also richer in arachidonic (20:4 n-6), eicosatrienoic (20:3 n-6), and docosatetraenoic (22:4 n-6) acids. Conversely, the milk of Japanese woman contained significantly higher percentages of monoun-saturates as palmitoleic, heptadecenoic, oleic, and polyunsaturates of n-3 series as alpha-linolenic, eicosapentaenoic, and docosahexaenoic acid.

Effects of dietary zinc and cadmium on tissue selenium concentration and glutathione peroxidase activity in rats fed DL-selenomethionine or sodium selenite.

The effects of dietary zinc (Zn) and cadmium (Cd) on tissue selenium (Se) concentration and glutathione peroxidase (GSH-Px) activity were studied in weanling male Wistar rats. One group of rats was fed a purified diet based on casein and sucrose, and the other rats used in a 2 x 2 x 2 factorial arrangement of treatment were fed this diet supplemented with 0.1 mg Se/kg, either as DL-selenomethionine or sodium selenite and plus 100 mg Zn/kg as zinc sulfate or 5 mg Cd/kg as cadmium chloride or both for 4 weeks. Se concentrations in plasma, erythrocytes, muscle, heart, and liver were significantly elevated by Zn. Cd significantly decreased Se concentration in muscle. Addition of Zn to the diets markedly increased (p less than 0.001) hepatic GSH-Px activity. However, Cd in the diets produced a significant increase (p less than 0.001) in erythrocyte GSH-Px activity. These results indicate that Zn level of marginal deficiency (8.6 mg/kg diet) can decrease Se availability and a small excess of Zn increases Se availability for hepatic GSH-Px activity.

Effect of fish oil and safflower oil in common Japanese diet on human plasma fatty acid composition.

The influence of fish oil and safflower oil contained in the common Japanese diet as the main dietary polyunsaturated fatty acid source on plasma fatty acids in ten female student volunteers (21-22 years old) was investigated. The subjects were divided into two groups and fed the experimental diets for five days. The total daily fat intake in the fish diet and safflower oil diet was 54.4 g and 56.2 g, respectively, and the fat derived from fish and safflower oil was 16 g and 23 g, respectively. The proportion of linoleic acid was reduced in the plasma of subjects fed the fish diet and increased in the plasma of subjects fed the safflower oil diet. The plasma levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were significantly elevated in the fish diet group. The ratio of EPA/arachidonic acid (AA) was higher, and those of n-6/n-3 and n-9/n-3 were lower in the plasma of subjects fed the fish diet when compared to the results obtained from plasma of subjects fed the safflower oil diet. From these results, it seems likely that fish oil in the common Japanese diet is a favorable source of plasma EPA and DHA even in such short term supplementation and with such a small amount of daily consumption.

Hepatic cysteine dioxygenase activity and sulfur amino acid metabolism in rats: possible indicators in the evaluation of protein quality.

Experiments were carried out to examine the possibility that the sulfur amino acid metabolism of rats may be an indicator of the nutritional value of dietary protein. Rats were fed diets containing 8, 16 or 24% of gluten, soy protein or casein for 3 wk. Hepatic cysteine dioxygenase activity, hepatic concentration of glutathione, cysteine and taurine and urinary taurine were examined. In addition, the sulfur amino acid metabolism of rats fed these diets fortified with the appropriate first limiting amino acid for 7 d was also examined. High urinary taurine excretion was observed in the three gluten groups, whereas very low urinary taurine excretion was observed with up to 24% soy protein or up to 16% casein. The hepatic hepatic cysteine dioxygenase activities of the gluten diet groups were higher than those of corresponding soy protein or casein diet groups, except that of rats fed the 24% casein diet. The hepatic concentrations of both glutathione and cysteine in gluten diet groups were also higher than those of corresponding soy protein or casein diet groups, except 24% soy protein and 16 and 24% casein diet groups. In rats fed the casein or soy protein diets urinary taurine excretion and hepatic cysteine dioxygenase activity increased with increasing methionine supplementation, the first limiting amino acid. Conversely, in rats fed the gluten diet both urinary taurine excretion and hepatic cysteine dioxygenase activity decreased with increasing lysine supplementation, the first limiting amino acid. These findings suggest that urinary taurine excretion and hepatic cysteine dioxygenase activity may be useful as sensitive indicators of the nutritional value of dietary protein.

Autoradiographic study of [35S]-cysteine and [1-14C]-cystine in pregnant and neonatal mice.

The distribution and fate of 35S from [35S]-cysteine and 14C from [1-14C]-cystine, both precursors to taurine in 17-day pregnant mice and (1-day-old) neonates were investigated by whole-body autoradiography following IV injection for the pregnant mice and IP injection for the neonates. Survival intervals were 30 min, 3 hr. In the dam, 35S and 14C were both highly incorporated into the pancreas. As very low uptake of [35S]-taurine in the pancreas was found in a previous study, it is reasonable to suggest that most radioactivity found in the pancreas represents cysteine. In maternal brain, brown fat, and myocardium, optical density and relative ratio (ODs of 35S and 14C in each tissue and organ/ODs of 35S and 14C in the blood) of 35S were significantly higher than those of 14C, assuming that most of 35S might be present as taurine in these regions. In the developing brain, 35S was found mainly in the differentiating neurons of the cortical plate, including the primordial hippocampal cell layer, and of the cerebellar cortical plate. Relative ratios of 35S in these cerebral regions were significantly higher than those of 14C, suggesting that most of 35S represents taurine.

Distribution of 35S-taurine in rat neonates and adults. A whole-body autoradiographic study.

The distribution of 35S-taurine in rat neonates and adults was investigated by wholy -body autoradiography. The neonates (4-day-old) were frozen in dry-ice hexane at 30 min, 1, 3 and 6 h after an intraperitoneal injection of 35S-taurine, whereas survival intervals for adult rats were 1 and 3 h. Whole-sagittal sections of the frozen rat, obtained by using a cryostat microtome were dried in situ and autoradiographed. In rat neonates and adults, 35S-taurine was mainly accumulated in the renal cortex, urine, feces, liver, eye (lens, vitreous fluid, retina), hypophysis, thymus, adrenal glands, nasal mucous membrane, salivary glands, gastric mucosa, small and large intestinal mucosa, choroid plexus, myocardium and sebaceous glands. In the rat neonate, such regions as the olfactory bulb, cerebrum, and cerebellum showed relatively high optical density.