Average Tail Length Research Articles

2-Nitropropane-induced DNA damage in rat bone marrow

DNA damage detected by the comet assay (single cell gel electrophoresis) and 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodG) formation in DNA in the bone marrow has been studied in groups of 6 male Wistar rats treated with a single i.p. injection of the carcinogen 2-nitropropane (2-NP, 100 mg/kg body weight) or vehicle. Twenty-four hours after 2-NP the average tail length in the comet assay in bone marrow cells was increased from 1.46±0.27 to 9.61±1.56 μm (mean±SD, p<0.01), and 8-oxodG levels in the DNA were increased from 1.04±0.50 to 5.14±2.42 per 10 5 dG ( p<0.01). There was a close correlation between the comet tail length and the 8-oxodG level ( r=0.89, p<0.05). The results indicate that 2-NP inflicts DNA damage in the bone marrow cells and thus could be leukemogenic.

Assessment of DNA damage in leukocytes from infected and malnourished children by single cell gel electrophoresis/comet assay

The alkaline single cell gel (SCG) assay is a sensitive electrophoretic technique for detecting the presence of DNA single strand breaks and alkali-labile damage in individual cells. This technique was used to assess and compare the level of DNA damage in peripheral blood leukocytes/lymphocytes from well-nourished children with infection, well-nourished children with infection and under drug treatment, and from malnourished infected children with and without previous drug treatment. The present study shows that severe infection is associated with a significant increase in DNA damage. The average migration length was five times greater in severely infected well-nourished children compared to that found in healthy, well-nourished children. The results obtained in this study indicate that malnutrition is another factor associated with an increase in DNA migration. The average tail length for malnourished, severely infected children was twice as great as that obtained for cells from well-nourished, severely infected children. We also detected a variable increase in DNA migration associated with treatment for severe infection. Nevertheless, the excessive heterogeneity, the concurrent number of drugs used and the limited size of the treated population precludes an accurate assessment of which drugs were involved in the increase in DNA damage. Further studies will be necessary involving a large number of patients to address the relation between levels of DNA damage and specific kinds of infection, various drug treatments, and the type and severity of malnutrition. The increased level of DNA damage in severely infected and malnourished children could be related to negative effects such as a deficient immune response resulting in an increased susceptibility to malignant transformation.

Differences in growth, morphometric traits, and male sexual maturity among Pacific white shrimp, Penaeus vannamei, from different commercial hatcheries

Postlarvae of Penaeus vannamei from four commercial hatcheries (lots) were divided between two laboratory sites. Body length, body weight, condition factor, male sexual maturity, and ratios of the tail length and carapace width to body length, were monitored at days 50, 80, 110, 170, 200, 230 and 270. There were small differences in body size between sexes within each lot at all age groups. Consistent differences were observed between sexes in the proportional variables for all age groups and sites. Males had a larger average tail length ratio than females, while females had a larger average carapace width ratio and higher average condition factor than males. Average tail length ratio of younger age groups was smaller and the average condition factor was lower than those of the older groups. Significant differences in all of the morphometric traits were found between sites, indicating that the environmental differences affected not only the growth but also the shape of the shrimp. Rank order of the lots for all of the morphometric traits varied among age groups and between sites. However, certain lots consistently exhibited significantly smaller values for the proportional variables than other lots, independent of age and site. Percent of maturing males was significantly different among lots, and the rank order was consistent for ages and sites. These results suggest the presence of genetic differences for morphometric traits and male sexual maturity among the shrimp hatchery lots, although the traits are largely affected by environmental variance.

Deadenylation of α1-Acid Glycoprotein mRNA in Cultured Hepatic Cells during Stimulation by Dexamethasone

During acute phase induction in rats, α1-acid glycoprotein (AGP) mRNA is modified by a reduction in poly(A) tail size (Shiels, B. R., Northemann, W., Gehring, M. R., and Fey, G. H. (1987) J. Biol. Chem. 262, 12826–12831). In the studies presented here, we analyzed AGP mRNA induction and poly(A) tail modification in both primary rat hepatocytes and in the rat hepatoma cell line HTC. Poly(A) tail shortening occurred during stimulation by both glucocorticoids and hepatocyte stimulating factor. Induction of AGP by the glucocorticoid dexamethasone resulted in an approximately 50-fold increase in transcription by 4 h, which was followed by an equally rapid decrease. The large mRNA pool that resulted from this early burst of transcription was very stable, having a half-life of well over 24 h, and the individual molecules in this pool had an average poly(A) tail length of 200–250 bases. This stable pool of AGP mRNAs was then deadenylated to form a pool with an average tail length of 20–50 bases; the time course of this shortening followed that seen in the liver. Ongoing RNA synthesis, but not ongoing protein synthesis, was required for shortening of the tail. In contrast to the conclusion of Shiels et al. (1987), our data indicate that deadenylation occurs in the cytoplasm rather than the nucleus. Our data also suggest that shortening of AGP mRNA represents a specific example of the general deadenylation seen in earlier studies of total cellular RNA.

発育期の運動処方に関する実験的研究

To get basic data on exercise prescription in the growing stages, it was attempted to investigate the growth of white albino rats (JCL : SD strain) under the various swimming loads. Following results were obtained.A. The effects of exercise prescription to small cage raising:1) Non-swimming small cage (7.5×15×20cm) group was resulted -17.5% accumulated food intake, -14.3% average body weight and -6.8% average tail length to the non-swimming normal cage (15×30×20cm) group.2) In 16 min and 96 min actual swimming time/week, small cage groups were little or no diminished on the difference of the body weight and tail length to each corresponded normal cage groups.B. The amount of swimming time and the peak value of growth:1) In 48 min actual swimming/week, peak values were observed on the femur length, gastrocnemius and femur weight.2) In 96 min actual swimming/week, peak values were taken on the tail length, body, heart and adrenal weight.3) In 384 min actual swimming/week, no peak value was observed, and significant decreases were indicated on the femur length, gastrocnemius and femur weight to the non-swimming.C. The growing difference between intermittent and continuous swimming:1) In 16 min and 96 min actual swimming/week, continuous (repetitions 16 min swimming and 2 min rest) groups were obviously higher than in intermittent (repetitions 2 min swimming and 2 min rest) groups on the food intake, tail and femur length, heart, adrenal, liver, kidney, gastrocnemius and femur weight, cross section area and marrow cavity area of femur, except the body and spleen weight.2) In 384 min actual swimming/week, however, continuous group was indicated such remarkable decrease on almost all tissues and organs that the body, spleen and gastrocnemius weight were showed lower than the non-swimming group.D. The tendency of growing process about training frequency and actual swimming time:1) It was found that the larger grow in training frequency (1 day, 3 days and 6 days/week) and actual swimming time (60 min and 120 min/week), the more increase in the food intake, heart weight, adrenal weight, breaking bending load, proportion of muscle fiber and average area/fiber in cross section of gastrocnemius.2) But, on 3 days training frequency in 60 min actual swimming and 1 day training frequency in 120 min actual swimming, the tail and femur length, and gastrocnemius and femur weight were the largest growth among these three training frequency.3) The bending strength of femur on 3 days training frequency was indicated the strongest one in both of 60 min and 120 min actual swimming groups.