Biomedical subjects

J Takano

Publications and source records attributed to J Takano.

At least 37 records · Page 2Linked to original sources

PubMed1986

Amplification and deletion of the amyE+-tmrB+ gene region in a Bacillus subtilis recombinant-phage genome by the tmrA7 mutation.

A 22.4-kilobase DNA fragment containing the tmrA7-amyR2-amyE+-tmrB+-aroI+ region of the Bacillus subtilis N7 chromosomal DNA was cloned into a recombinant B. subtilis bacteriophage, p11-AA248. The amyE+-tmrB+ gene region, approximately 12.6 kilobases, in the phage genome was amplified in a tunicamycin-resistant (Tmr) Amy+ AroI+ transductant of B. subtilis by p11-AA248. On the other hand, the amyE+-tmrB+ region in the genomes of 80 to 90% of the phage particles was deleted when the phages were induced from the Tmr Amy+ AroI+ transductants by treatment with 1.0 micrograms of mitomycin C per ml. From analyses of the physical maps and DNA nucleotide sequences in the junction region of the deleted phage genome and the parental DNA fragments, it is suggested that the deletion occurred within a direct repeat sequence composed of 18 base pairs. The endpoints of the amplified gene region seemed to be closely related to both terminal regions of the deleted DNA.

Bacillus subtilis↗

PubMed1985

Genetic analysis of developmental mechanisms in hydra. XVI. Effect of food on budding and developmental gradients in a mutant strain L4.

Effect of food was examined on the budding rate and the developmental gradients of a mutant hydra strain L4. This mutant strain has very high levels of head-inhibition potential gradient along its body axis (Takano & Sugiyama, 1983). It also has a reduced budding capacity when it is cultured using brine shrimp nauplii as food, but its budding capacity is significantly improved when a small amount of tubifex worm tissue is added to its diet of brine shrimp (Takano, 1984). To test whether or not this change of budding rate is correlated with the change in the levels of the head-activation or head-inhibition potential gradients, L4 animals were cultured on the diet of brine shrimp with or without addition of tubifex worm tissue and the budding rates and the gradient levels were examined in these animals. The results showed that food affected the budding rate in L4 without affecting its gradient levels. This suggests that the gradient levels and the budding rate in L4 are are uncorrelated to each other, and that therefore the high levels of head-inhibition potential are not the cause for the low budding rate in this strain (cf., Takano & Sugiyama, 1983).

Animals↗

PubMed1984

Genetic analysis of developmental mechanisms in hydra. IX. Effect of food on development of a slow-budding strain (L4).

A mutant hydra strain L4 produces buds at a much lower rate than the standard wild-type strain (105) when fed with brine shrimp nauplii (T. Sugiyama and T. Fujisawa, 1979b, Dev. Growth Differ. 21, 361-375). It was found that addition of a small amount of tubifex worm tissue to the normal brine shrimp diet significantly improved the budding rate of L4 but not of 105. Detailed examination and comparison of food effect on various developmental processes in L4 and 105 have provided the following observations. (1) L4 development is strongly affected by food and has significantly lower rates than 105 in all the developmental parameters examined which involve the bud initiation process. In contrast, such effects and differences are not observed in parameters not involving bud initiation. These observations suggest that L4 has a defect(s) in its bud initiating mechanisms and that the expression of this defect is somehow strongly affected by food. (2) Epithelial cells proliferate in L4 nearly as rapidly as in 105 and without food effect. Epithelial cells produced by cell division are mostly utilized to form buds in mature 105 polyps. These cells, however, are not fully utilized for this purpose in L4 polyps which bud very slowly. Instead, they appear to be somehow lost from tissue in these animals.

Animals↗

PubMed1984

Genetic analysis of developmental mechanisms in hydra. XII. Analysis of chimaeric hydra produced from a normal and a slow-budding strain (L4).

Chimaeric hydra strains were produced from a normal strain (105) and a naturally-occurring mutant strain (L4) which has a large polyp size, a low budding rate and a high head-inhibition potential. Various properties of the chimaeras were then examined and compared to those of the two parental strains. Hydra tissue consists of three cell lineages: the ectodermal epithelial, the endodermal epithelial and the interstitial cell lineages. Using the methods recently developed by Marcum & Campbell (1978b) and by Wanek & Campbell (1982), six chimaeric strains were produced which contained six different combinations of the three cell lineages from 105 and L4. Evidence obtained from the comparison of the chimaeras and their parental strains indicates that the ectodermal epithelial cell lineage in L4 is primarily responsible for the large polyp size and the low budding rate of this strain, whereas the endodermal epithelial cell lineage is largely, and the interstitial cell lineage is also partially, responsible for the high head-inhibition potential in L4. This suggests that the mechanisms determining the occurrence and location of bud formation and the mechanisms determining the inhibition potential levels are not related to each other (cf. Takano & Sugiyama, 1983; Bode & Bode, 1983). Evidence was also obtained which suggests that the levels of the head-activation and head-inhibition potentials in the chimaeras are determined independent of each other, apparently without the cross-catalytic relationship between them assumed in the Gierer-Meinhardt model (Gierer & Meinhardt, 1972; Meinhardt & Gierer, 1974).

Animals↗

PubMed1983

Genetic analysis of developmental mechanisms in hydra. VIII. Head-activation and head-inhibition potentials of a slow-budding strain (L4).

Morphogenetic potentials involved in head formation were examined in a hydra strain (L4) which has a very low budding rate and a large polyp size, and the results were compared to those of the normal strain (105). Hydra tissue has two types of antagonistic morphogenetic potentials which are thought to play important roles in head structure formation: the head-activation potential and the head-inhibition potential. Lateral tissue transplantation (Webster & Wolpert, 1966) was used to compare the levels of the two potentials in L4 and the normal strain. It was found that the intact polyp of L4 has a nearly normal or slightly lower head-activation potential but a significantly higher head-inhibition potential than the normal strain. During the course of regeneration after head amputation, the levels of the two potentials in L4 changed in significantly different patterns from those in the normal strain. These abnormalities of the two potentials may be responsible for the developmental and morphological abnormalities in L4. The significance of these observations is discussed in light of the current hydra pattern formation models (Wolpert, Hornchurch & Clarke, 1974; Meinhardt & Gierer, 1974).

Animals↗

PubMed1979

Incidence and clinical significance of HBe antigen and antibody in HBsAg-positive various liver diseases.

The HBeAg was detected in 5 of 24 patients with acute type B hepatitis (20.8%), 33 of 95 with chronic hepatitis (34.7%), 6 of 33 with liver cirrhosis (18.2%), and 3 of 39 with hepatocellular carcinoma (7.7%). On the other hand, anti-HBe was found in 4.2% of acute hepatitis, 18.9% of chronic hepatitis, 9.1% of liver cirrhosis, and 12.8% of hepatocellular carcinoma. We found that an early detection of HBeAg in patients with acute hepatitis is of no prognostic value, but its persistence may provide the earliest evidence of potential chronicity. In chronic liver diseases, HBeAg-positive cases showed remarkable fluctuations of serum transaminase levels, severe histological changes and poor responses to treatment. Many of the HBeAg-positive patients lost their initial positivity of HBeAg within six months or one year and in some cases serocoverted to anti-HBe after acute exacerbation. Follow-up study more than several years revealed that the presence of anti-HBe reflect an inactive stage and a more favorable outcome, whereas persistence of HBeAg may provide an active and continuing hepatocellular damage. From these results, we believed that serial measurements of HBeAg/anti-HBe system are useful prognostic marker in patients with HBsAg-positive liver disease.

Acute Disease↗

PubMed1974