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Biomedical subjects

J Nagai

Publications and source records attributed to J Nagai.

At least 127 records · Page 7Linked to original sources
PubMed1978

Induction of ornithine decarboxylase in synchronized BHK cells by calf serum after a short period of serum-starvation.

Addition of calf serum to serum-starved cultures of synchronized BHK cells induced temporary production of ornithine decarboxylase, irrespective of the phase of the cell cycle of the BHK cells. The induction depended on the duration of serum starvation and on the amount of serum added. In addition, incorporation of 3H-thymidine into the acid-insoluble fraction of BHK cells in the S phase was stimulated by this treatment.

Animals↗
PubMed1978

Accumulation of zymosterol in yeast grown in the presence of ethionine.

In order to identify the methyl acceptor for the methylation of sterol side-chains in ergosterol biosynthesis, Saccharomyces cerevisiae (wild type) was grown in the presence and absence of ethionine which was expected to be an inhibitor of the methylation. Gas-liquid chromatographic analyses of the sterols in the cells grown in the absence of ethionine showed that ergosterol was the most abundant sterol. On the other hand, a sterol, named sterol Z, accounted for more than 50% of the total sterols in the cells grown in the presence of ethionine. As a result of experiments to raise the yield of sterol Z, the best concentration of DL-ethionine for the production was found to be 1.0 mM. The use of the methionine-less mutant was less effective for the production of sterol Z. Sterol Z was isolated by repeated TLC and was identified as zymosterol from its melting point, GLC and mass spectrometry. The role of zymosterol and other sterols as the methyl-acceptor sterol in ergosterol biosynthesis is also discussed.

Cholestadienols↗
PubMed1978

Correlation between direct and maternal genetic effects on body weight in mice.

A new method to estimate the correlation between additive direct genetic effects (Ao) and additive maternal genetic effects (Pm) on body weight was devised to apply to crossfostering data in mice. The correlation between Ao on body weight at 42 days (adult age) and Am on body weight at 12 days (preweaning age) was estimated as 0.561. The nature of this correlation was defined genetically.

Animals↗
PubMed1978

Relationship between milk yield and mammary gland development in mice.

Female mice from four lines exhibiting different nursing ability (as measured by mean 12-day weight of eight offspring within a nursed litter) were used to examine milk yield, body size, feed intake, and cellular development of mammary glands and liver. Three selected lines exceeded the control line in milk yield and mammary gland and liver weights. They had more total deoxyribonucleic acid, ribonucleic acid, and protein contents in both mammary gland and liver tissues than the control. Phenotypic correlations between milk yield and deoxyribonucleic acid contents of mammary glands and liver were .39 and .35, while correlations between milk yield and protein to deoxyribonucleic acid ratio of mammary glands and livers were .04 and .11. Milk yield was correlated closely with body size .57 and with feed intake .55. Milk yield was related more to cell number than to cell size of the mammary glands and liver, and large amounts of milk were produced by heavy dams with substantial feed intake.

Animals↗
PubMed1977

Changes in ornithine decarboxylase activity and cyclic adenosine-3'-5'-monophosphate concentrations during the cell cycle of synchronized BHK cells.

BHK cells were synchronized by excess thymidine treatment, which resulted in approximately 90% synchrony. The activity of ornithine decarboxylase (ODC), the rate-limiting enzyme in polyamine biosynthesis, elevated in early S phase, decreased in G2 + M and G1 phase and then increased during late G1 approximately second round of early S phase. The concentration of cyclic adenosine-3'-5'-monophosphate (cAMP) gradually decreased during S approximately G2 + M phase and then increased during late G1 approximately second round of early S phase, preceding that of ODC activity. The data suggest that ODC activity might be regulated by cellular cAMP level.

Carboxy-Lyases↗
PubMed1977

Evaluation of mouse lines for maternal performance and growth of offspring.

Crossfostering sets of mice each containing four dams representative of three selected lines (M, W, and B) and one control (C) were prepared in each of two populations (P and Q) to compare nursing ability of the mother and the intrinsic growth potential of the offspring among lines within populations. The descending order of line performance for the nursing ability, as measured by mean 12-day weight of eight offspring within a nursed litter, was M (8.48 g),W (8,47 g), B (7.88 g) and C (7.22 g) in population P; and W (10.16 g), M(9.83 g), B (9.56 g), and C (9.01 g) in population Q. Dams from line W had the heaviest body weight after parturition and consumed 176.7 g of feed in population P and 191.7 g in population Q during 12 days of lactation. The order of lines for growth potential measured by 42-day weight was W (30.83 g), B (24.60 g), M (24.36 g), and C (22.61 g) in population P; and W (40.19 g), B (31.35 g), M (29.98 g), and C (27.81 g) in population Q. These results were compared with those from a conventional line comparison where mothers reared their own offspring. Between the two comparisons, line order differed for nursing ability in population P but not in population Q, and did not differ for 42-day weight.

Animals↗
PubMed1976

Partitioning average and heterotic components of direct and maternal genetic effects on growth in mice using crossfostering techniques.

Crossfostering was performed using lines selected for increased 6-week body weight (H6) and increased 3-to 6-week postweaning gain (M16) and their reciprocal F1 crosses as nurse dams in the selected crossfostering group, and base population controls (C2, ICR) and their reciprocal F1 crosses in the control group. The offspring suckled were H6, M16 and F2 crosses in the selected group, and C2, ICR and their F2 crosses in the control group. Measurements taken on the individual offspring were body weights at birth (WB) and at 12, 21, 31, 42, and 63 days (W12, W21, W31, W42 and W63, respectively) and weight gains between adjacent ages (GB-12, G12-21, G21-31, G31-42 and G42-63, respectively). Least squares constants fitted to populations of genetic and nurse dams were used to calculate specific linear contrasts. Correlated responses to selection in average direct genetic effects were significant and positive for all traits examined in both H6 and M16, while the correlated responses in average maternal genetic effects were negative in M16 and negligible in H6. Selection response was primarily due to average direct genetic effects while the contribution of average maternal genetic effects was of secondary importance. The response in average direct genetic effects was smaller in M16 for postweaning weights (W31, W42 and W63). The correlated responses in average maternal genetic effects were consistently smaller in M16 than in H6. Direct heterosis was significant for all traits except for G12-21 and G42-63 in the control group, whereas maternal heterosis was significant for weight gains at early ages and for body weights. Direct heterosis tended to be larger than maternal heterosis in both selected and control crosses. Percent direct heterosis for body weight was larger in the selected crosses relative to the control crosses through 31 days of age, but the trend was reversed by 63 days. Percent maternal heterosis was consistently larger in the selected crosses.

Animals↗
PubMed1976

Genetic analysis of nurse dams selected for six-week body weight or postweaning gain in mice.

A modified crossfostering technique was developed to compare the performance of nurse dams in selected and control populations of mice. The H6 and M16 populations were selected for increased 6-week body weight and 3- to 6-week postweaning gain, respectively, while the C2 and ICR populations were the respective controls. Crossfostering was performed using H6, M16 and their reciprocal F1 crosses as nurse dams in the selected crossfostering group and C2 ICR and their reciprocals in the control group. Measurements recorded for nurse dams included mean body weight of 8 young within a nursed litter at birth (MWB) and 12 days of age (MW12). The latter was used as a measure of postnatal maternal performance. Other traits recorded for nurse dams were number born (NB), body weight at parturition (DWP) and 12 days postpartum (DW12), and weight gain (DWG), feed intake (FED) and efficiency (EFF = DWG/FED) for the first 12 days of lactation. The correlated response in MW12 was negative (P less than .01) for M16 and essentially zero for H6. Both lines exhibited positive (P less than .01) correlated responses in DWP and DW12 and no change in EFF. Only the H6 line increases significantly in DWG and FED as a result of selection. NB increased in M16 and H6, but was significant for the latter population only. Population differences in selection response [(M16-ICR)-(H6-C2)] were significant for FED only, primarily due to average direct genetic effects. Direct comparisons of M16 and H6 indicated that M16 was larger in DWP and DW12 but smaller in DWG and EFF. Average direct genetic effects favored M16 for NB, DWP, and DW12, whereas average maternal genetic effects favored H6 for NB, DWP, DW12 and FED. Percent direct heterosis, in F1 crosses of selected populations was significant for MW12 (13.7%) ,FED (10.8%) and NB (11.4%). Direct heterosis in F1 crosses of the controls was significant for MW12 (9.4%), NB (6.6%), DWP (3.5%), DW12 (3.3%) and FED (4.4%). The effects of MW12, DWG and metabolic body size (MBS) accounted for 47% of the variation in FED, pooled within populations. Of these variables, MW12 accounted for the highest proportion (32%) of variation in total feed intake.

Animals↗