Mutagenicity of malonaldehyde, a decomposition product of peroxidized polyunsaturated fatty acids.

Incubation of histidine requiring auxotrophs of the bacterium Salmonella typhimurium with malonaldehyde, a three-carbon dialdehyde, produced an increased number of revertants in specific strains. Mutagenesis was only observed in frameshift mutants with normal excision repair and did not occur in those base-pair substitution mutants tested. The results are consistent with the cross-linking of bacterial DNA by malonaldehyde leading to mutagenesis expressed through the error-prone repair system.

Direct alkylation of 2'-deoxynucleosides and DNA following in vitro reaction with acrylamide.

Reaction of the rodent carcinogen acrylamide (AM) at pH 7.0 and 37 degrees C for 10 and 40 days with 2'-deoxyadenosine (dAdo), 2'-deoxycytidine (dCyd), 2'-deoxyguanosine (dGuo), and thymidine (dThd) resulted in the formation of 2-formamidoethyl and 2-carboxyethyl adducts via Michael addition. The alkylated 2'-deoxynucleoside adducts isolated (% yield after 40 days) were 1-(2-carboxyethyl)-dAdo (1-CE-dAdo) (8%), N6-CE-dAdo (21%) (via Dimroth rearrangement of 1-CE-dAdo), 1-CE-dGuo (4%), 7-(2-formamidoethyl)-Gua (7-FAE-Gua) (6%), 7, 9-bis-FAE-Gua (1%) (formed by reaction of AM with depurinated 7-FAE-Gua during the course of the reaction), and 3-FAE-dThd (4%). The products isolated following in vitro reaction of AM with calf thymus DNA at pH 7.0 and 37 degrees C for 40 days were (nmol/mg DNA) 1-CE-dAdo (5.5), N6-CE-dAdo (1.4), 3-CE-dCyd (2.8), 1-CE-dGuo (0.3), and 7-FAe-Gua (1.6). Compound 3-FAE-dThd was not detected. Structures were assigned on the basis of chemical properties, UV spectra, and electron impact, chemical ionization, desorption chemical ionization, Californium-252 fission fragment ionization, and fast atom bombardment mass spectra. A facile hydrolysis of the amide group to a carboxylic acid was observed when AM alkylated a ring nitrogen adjacent to an exocyclic nitrogen atom. In previous studies, we had observed an analogous phenomenon when studying the in vitro reactions of acrylonitrile with DNA, i.e., a facile hydrolysis of nitrile to carboxylic acid when acrylonitrile alkylated (via Michael addition) a ring nitrogen adjacent to an exocyclic nitrogen. Since the nitrile group hydrolyzes to a carboxylic acid via an amide intermediate, we had hypothesized in the present study that the same facile hydrolysis of amide to carboxylic acid would occur under identical stereochemical conditions as had occurred with the nitrile group. Thus, in vitro alkylation of calf thymus DNA by both acrylonitrile and, in the present study, AM, resulted in mixed adduct formation.

Reactions of propylene oxide with 2'-deoxynucleosides and in vitro with calf thymus DNA.

Propylene oxide (PO) is a direct-acting mutagen and rodent carcinogen. We have studied how PO modifies 2'-deoxynucleosides at pH 7.0-7.5 and 37 degrees C for 10 h. PO reacts as an SN2 alkylating agent by forming the following 2-hydroxypropyl (HP) adducts: N6-HP-dAdo (7% yield), 7-HP-Gua (37%) and 3-HP-dThd (4%). Alkylation at N-3 of dCyd resulted in conversion of the adjacent exocyclic imino group at C-4 to an oxygen (hydrolytic deamination) with the formation of a dUrd adduct, 3-HP-dUrd (14%). Ultraviolet spectroscopy and mass spectrometry were used for the structural determination of these adducts. Confirmation of the unexpected 3-HP-dUrd adduct was provided by an accurate mass measurement technique where diagnostic ions in the mass spectra of 3-HP-dUrd were measured to within 0.0005 atomic mass units of the predicted mass. PO was reacted in vitro with calf thymus DNA (pH 7.0-7.5, 37 degrees C, 10 h) and yielded N6-HP-dAdo (1 nmol/mg DNA), 3-HP-Ade (14 nmol/mg DNA), 7-HP-Gua (133 nmol/mg DNA) and 3-HP-dUrd (13 nmol/mg DNA). A mechanism for the hydrolytic deamination of 3-HP-dCyd to 3-HP-dUrd involving the OH on the HP side chain is proposed. This cytosine to uracil conversion may play a role in the mutagenic and carcinogenic activity of this epoxide.

Split-circulation assist device facilitates heart failure management and increases effects of intra-aortic balloon pumping.

The split-circulation assist device (SCAD) comprises an intra-aortic balloon pump (IABP), percutaneous cardiopulmonary support (PCPS) equipment, and two occlusion balloons that occlude the descending thoracic aorta by alternate inflation. With the SCAD, the failing heart, assisted by IABP, maintains only the upper 25-30% of the entire circulation without any interference by bypass flow from PCPS. An animal experiment indicated that a given rise in cardiac output caused an increase in aortic pressure in the SCAD group about three times greater than that in the control group (an ordinary combination of IABP and PCPS). Thus, by causing greater increases in arterial pressure, the SCAD may make possible detection of subtle increases in cardiac output, and therefore early detection of cardiac recovery. Multiple regression analysis from the pressure and flow data obtained in another experiment indicated that the SCAD facilitated the prediction of cardiac outputs and loads by preventing the bypass flow rate from influencing the aortic pressure. In addition, the SCAD may enhance cardiac assistance by increasing the effects of IABP. Therefore, the SCAD is a useful and potent new circulatory assist device that can facilitate both timely weaning from PCPS and heart failure management.

Inbreeding and effective population size of Japanese Black cattle.

The objective of this research was to estimate the amount of inbreeding and effective population size of the Japanese Black breed using pedigree records from bulls and heifers registered between 1985 and 1997. Inbreeding was quantified by three F-statistics: actual inbreeding, inbreeding expected under random mating, and inbreeding due to population subdivision. During the period of 1985 to 1997, the inbreeding expected under random mating increased from 2.3% to 5.0%, whereas the increase of actual inbreeding was more gradual (from 4.7% to 5.4%). The inbreeding due to population subdivision decreased almost linearly and reached 0.5% in 1997, indicating that genetic subdivision of the Japanese Black cattle population has essentially disappeared. The effective size of the breed was estimated from the increasing rate of inbreeding expected under random mating. In the earlier half of this period (1986 to 1990), the breed maintained an effective size of approximately 30. However, after 1991 the effective size sharply decreased and the harmonic mean between 1993 and 1997 was only 17.2. The main cause of this reduction of the effective size was considered to be the intensive use of a few prominent sires. To increase the effective size, an upper limit in the use of AI semen per sire should be imposed.

Identification of mitochondrial DNA substitutions related to meat quality in Japanese Black cattle.

Complete sequences of mitochondrial (mt) genomes of eight Japanese Black cattle were determined to investigate the relationships between mt deoxyribonucleic acid (DNA) displacement loop (D-loop) types and other mtDNA regions and to identify the variation in the coding region that may influence the economic traits. The survey of mitochondrial sequences in the encoding region revealed 14 substitutions including six antonymous substitutions and one in 16S ribosomal ribonucleic acid (rRNA). Three methods of polymorphic DNA analyses (polymerase chain reaction [PCR]-restriction fragment length polymorphism [RFLP], mismatch PCR-RFLP, PCR-single-strand conformation polymorphism [SSCP]) were performed on these seven candidate substitutions (base pair [bp] 2,232, 12,158, 12,908, 13,310, 14,122, 14,140, and 14,565) for 202 Japanese Black cattle. The substitution of bp 13,310 was observed in all samples, but not in the reference sequence, indicating that this is a minor substitution or a sequencing mistake in the reference sequence. The substitutions at bp 14,122, 14,140, and 14,565 were observed in only a few samples, suggesting that these were also minor substitutions. The substitutions at bp 2,232 (16S rRNA), 12,158, and 12,908 (reduced nicotinamide adenine dinucleotide-ubiquinone oxidoreductase chain-5) were closely related to mitochondrial D-loop types that have previously been related to differences in the carcass traits of Japanese Black cattle. Evaluation of the effects on six carcass traits with mixed model procedures suggests that the bp 2,232 substitution affects longissimus muscle area and beef marbling score. The substitution at bp 2,232 is a strong candidate for the mitochondrial effect on meat quality.

Effect of mitochondrial DNA variation on carcass traits of Japanese Black cattle.

Japanese Black fattening steers were used to examine relationships between carcass traits and mitochondria displacement loop (D-loop) variations. The D-loop region of Japanese Black cattle was sequenced and revealed 26 mitochondrial haplotypes defined by 25 polymorphic sites. The haplotypes were classified into five mitochondrial types (type 1 to 5) using the unweighted pair-group method with arithmetic means. Carcass weight, longissimus muscle area (LMA), rib thickness, subcutaneous fat thickness, yield estimate, and beef marbling score (BMS) were compared among five mitochondrial types with BLUP procedures. Significant differences between mitochondria types were detected for LMA and BMS. Difference (P < . 05) was observed between mitochondrial types 2 and 4 for LMA. There was a highly significant difference (P < .01) in BMS between types 2 and 4. Difference (P < .05) was also found between types 1 and 4 on BMS. These results suggest that cytoplasmic genetic effects are important sources of variation for carcass traits in Japanese Black cattle.

Induction of ornithine transcarbamylase activity with egg yolk in chick kidney.

The present paper shows the effect of egg yolk on chick kidney ornithine transcarbamylase (OTC) activity. A 90% egg yolk diet resulted in an increase of about 2.5-fold in kidney OTC activity. Enzyme activity increased gradually during incubation and after hatching and then decreased in accordance with disappearance of egg yolk from the residual yolk sac. Maximum activity - 10-fold that of the 14th day embryo - was observed between Days 4 and 7 in chicks fed the control diet. This maximum was shifted to between Days 14 and 21 and to a higher level by feeding a 90% egg yolk diet. Feeding the egg yolk diet to 14- or 21-day-old chicks that had received commercial chick starter from Day 2 also caused an increase of OTC activity. It was suggested that egg yolk or an ingredient(s) induces chick kidney OTC and that utilization of egg yolk promotes the formation of OTC in chick kidney during embryonic development and during subsequent growth of the chick.

A further study on the left-right asymmetry of the planum temporale.

By means of a rubbed copy method using India ink and an image-analysis system (IBAS 2000), the areas of 106 left-right plana temporalia were compared using fixed brains of both sexes. The left planum was of a larger size than the right planum in two-thirds of the cases. This result was confirmed statistically by the least-squares analysis of variance method (p < 0.01).

[Mitral valve surgery using combined superior-transseptal approach to the left atrium].

Although various approaches to the mitral valve surgery have been tried in the past, it still may be difficult to obtain a good surgical field, particularly in cases of small left atrium or reoperation. We performed mitral valve surgery in 6 patients using the combined superior-transseptal approach to the left atrium proposed by Berreklouw. Exposure of the mitral valve was excellent and the operative procedure was simple in all cases. There were no differences in bleeding volume, length of operation or complication of arrhythmia between patients treated with this new approach and a group treated with conventional approach in our institute.

Heritabilities and genetic correlations of fatty acid compositions in longissimus muscle lipid with carcass traits in Japanese Black cattle.

Fatty acid composition and carcass traits of 2,275 Japanese Black steers and heifers were analyzed to estimate the heritabilities and genetic correlations using the REML procedure. Slices of LM at the 6th to 7th rib section were minced and homogenized, and total lipids were extracted for the analysis by a gas chromatograph. Oleic acid accounted for the majority (51.3%), followed by palmitic (26.4%) and stearic (10.8%) acids. Heritabilities of carcass traits were moderate to high, ranging from 0.34 to 0.61, and heritabilities of individual fatty acids varied largely from 0.00 to 0.78. Those of MUFA, SFA, and PUFA were estimated to be 0.68, 0.66, and 0.47, respectively. Predicted breeding values for MUFA in 99 sires ranged from -3.0 to 5.4%. Genetic correlations of fatty acid compositions with carcass traits were generally weak (-0.28 to 0.39). Low but positive genetic correlations were obtained between beef marbling, on which emphasis of selection has been placed, and oleic acid (0.19) or MUFA (0.23). The results indicated the possibility not only for genetic improvement in fat quality traits but also simultaneous improvements with carcass traits by appropriate selection program.

Stearoyl-CoA desaturase mRNA expression during bovine adipocyte differentiation in primary culture derived from Japanese Black and Holstein cattle.

Stearoyl-CoA desaturase (SCD) catalyzes the synthesis of monounsaturated fatty acids (MUFAs). In cattle, the MUFAs are related to softness and flavor of meat. In order to investigate gene expression profile during bovine preadipocyte differentiation, we isolated stromal-vascular cells from perirenal adipose tissues of Japanese Black and Holstein steers. Gene expression level of adipocyte type fatty acid binding protein (FABP4), SCD, sterol regulatory element binding protein 1 (SREBP1) and CCAAT/enhancer binding protein alpha (C/EBP-alpha) were elucidated by real-time PCR assay. The levels of SCD mRNA expression were significantly increased to 10.8 and 6.3-fold in Japanese Black and Holstein, respectively, on day 1 of the culture. The difference in SCD expression between the two breeds may reflect differences in the fat development characteristics of the cattle breeds. Although transcription factors SREBP1 and C/EBP-alpha are supposed to regulate SCD expression, expression levels of the two factors were not completely consistent with that of SCD.

Effect of sire mating patterns on future genetic merit and inbreeding in a closed beef cattle population.

Alternative breeding strategies were simulated based on the population structure of the Tajima strain of Japanese Black cattle. An analysis of the population structure revealed that some sires up to 20 years of age have been used in Tajima. In addition, 95% of newborn calves were the progeny of only 20 sires, and their mating frequencies were significantly skewed. The current average inbreeding coefficient and founder genome equivalents of the strain were estimated to be 0.199 and 2.25, respectively. Average inbreeding coefficient is expected to reach 0.394 within 27 years. Thus, different breeding strategies were assessed for their effect on the level of inbreeding and average genetic merit. We compared strategies that (1) halve the sire service period, (2) double the number of mating sires and (3) lower the skewed sire mating frequency and optimize the frequency for weighted genetic merit and diversity. Reducing the service period yielded a 7.0-12.0% reduction in the rate of inbreeding while maintaining almost the same genetic gain. Increasing the number of sires resulted in a 19.3-21.3% reduction in inbreeding with a corresponding 1.6-8.4% reduction in gain. The rates of inbreeding from the optimized strategies decreased as the weight on genetic diversity increased. However, a strategy that emphasized only genetic gain yielded lower gain than other strategies because the strategy allowed only one sire to mate, resulting in reduced genetic variance and low accuracy of genetic evaluation. In contrast, a strategy with no emphasis on genetic gain when determining mating frequency resulted in reductions of 16.0% and 63.2% in genetic gain and inbreeding, respectively. The strategies examined here are easily applicable and can be expected to reduce immediate loss of genetic diversity.

Genetic analysis of calf market weight and carcass traits in Japanese Black cattle.

Heritabilities of and genetic correlations between additive direct and maternal genetic effects for calf market weight, and additive direct genetic effects for carcass traits, were estimated for Japanese Black cattle by REML procedures under 2-trait animal models. Data were collected from calf and carcass markets in Hyogo and Tottori prefectures and analyzed separately by prefecture. Calf market weight was measured on 42,745 and 23,566 calves in Hyogo and Tottori, respectively. Only the fattening animals with calf market weight were extracted from the carcass database and used for estimation. The carcass traits analyzed were carcass weight, ribeye area, rib thickness, subcutaneous fat thickness, yield estimate, beef marbling score, and 4 meat characters (color, brightness, firmness, and texture). Direct and maternal heritabilities for calf market weight were estimated to be 0.22 and 0.07 in Hyogo, and 0.37 and 0.15 in Tottori, respectively. The estimates of heritabilities for carcass traits were moderate to high in both prefectures. The estimates of direct-maternal genetic correlations for calf market weight were positive (0.17) in Hyogo and negative (-0.63) in Tottori. The direct effect for calf market weight was positively correlated with the direct effect for carcass weight (0.87 and 0.56 in Hyogo and Tottori, respectively) but negatively correlated with the direct effect for beef marbling score (-0.10 in both prefectures). The estimates of genetic correlations between the maternal effect for calf market weight and the direct effects for carcass traits varied from -0.13 to 0.34 in Hyogo and from -0.14 to 0.15 in Tottori. Because direct and maternal genetic effects for early growth traits can be evaluated from calf market weight data in the production system of Japanese Black cattle, this information should be incorporated into selection and mating schemes of the breed.

Evaluation of genetic diversity in Japanese Brown cattle population by pedigree analysis.

The Japanese Brown is the second most common domestic beef breed in Japan. However, nowadays this breed is facing reduction in numbers because of pressure from a profitable domestic breed. This breed is uniformly characterized by its brown coat colour, but is comprised of two isolated sub-breeds, Kumamoto and Kouchi, each possessing a different gene pool. Pedigree analyses were carried out for the two sub-breeds using the pedigree records of animals born from 1970 to 2000. The effective population size has been found to be consistently reducing during the last three decades in both sub-breeds. The current effective sizes were estimated to be 25.5 and 6.0 for the Kumamoto and Kouchi sub-breeds, respectively. The estimate of the effective number of founders (N(ef)) in the Kumamoto sub-breed decreased from 152.1 to 74.4; that of non-founders (N(enf)), from 41.7 to 5.3; and that of founder genome equivalents (N(ge)), from 32.7 to 4.9. The corresponding changes in the Kouchi sub-breed were from 108.2 to 79.4, 16.2 to 4.1, and 14.1 to 3.9. Increasing differences between the two genetic diversity indices in the sub-breeds indicate that the greater part of the reduction of genetic diversity can be attributed to genetic drift that accumulated in the non-founder generations. A comparison with published estimates for several cattle breeds suggests the extremely limited genetic diversity of Japanese Brown. In addition to the avoidance of further reduction of genetic diversity, it will be important to counteract the process of breed decline by establishing a production system to efficiently utilize the unique characteristics of this breed and by developing links between the breed and products with market value.

Prediction of inbreeding in commercial females maintained by rotational mating with partially isolated sire lines.

The solution to the inbreeding problem for livestock breeds in commercial use is often complicated by hierarchical population structure, in which favourable genes are accumulated in the upper level of the hierarchy (breeding population) by artificial selection and the genetic progress achieved is transferred to the lower level through migration of males. When the breeding population is subdivided into several isolated lines, rotational mating with the lines has been shown to be quite an effective system to reduce the short- and long-term inbreeding of commercial females in the lower level. In practice, however, some amount of migration should be allowed among the lines to reduce the rate of inbreeding in each line. In this study, we developed the recurrence equation for the inbreeding coefficient of the commercial females maintained by the rotational mating with partially isolated lines. Numerical computations were carried out to evaluate the effect of the migration on the efficiency of the rotational mating. It was shown that even with a small amount of migration among the lines, the inbreeding of commercial females is substantially inflated. However, when four or five lines are available, the inbreeding coefficient of commercial females can be suppressed to an acceptable level, irrespective of the effective size of line and the migration rate. Application of the mating system to the population of Japanese Black cattle was also examined.

Conservation of genetic diversity in the Japanese Black cattle population by the construction of partially isolated lines.

In the Japanese Black cattle population, five genetically divergent sub-populations have played important roles as suppliers of breeding stocks to the entire breed. We supposed a situation where five lines were constructed from each of the five subpopulations, and applied to this set of lines a management plan to conserve genetic diversity. Assuming that the male migration pattern among the lines followed the island model, we assessed the optimum male migration rate and required male numbers in each line, satisfying the following three conditions simultaneously: (i) the rate of inbreeding in each line was below 0.01 per generation; (ii) at least 97% of the initial genetic diversity was preserved after 10 generations; and (iii) more than 50% of the genes in an initial line were retained in the line after 10 generations. We found that approximately one breeding male should be selected per year and one breeding male should be exchanged among the lines per generation in each line to satisfy these three conditions. Numerical analysis with the migration rates actually observed among the five subpopulations demonstrated that the initial genetic differentiation among the lines was rapidly decayed by an asymmetrical migration pattern. For a successful plan, migration among lines should be strictly managed.

Short-term in vitro bioassays: applicability to air monitoring in the coal conversion and shale oil industries.

Short-termbioassays such as that of Ames and co-workers may be a practical method of monitoring industrial environments for the presence of biologically active and potentially hazardous materials. In general, these assays detect agents that cause damage to DNA which may lead to mutations, cancer, birth defects and to other diseases. Used to monitor industrial environments, such tests can indicate the presence of biologically active materials and can detect changes in the levels of these materials in the air. This paper reviews the types of bioassays which are presently available and considers their applicability to evaluation of occupational exposures in the coal conversion and oil shale industries. As no direct assessment of the degree of human health hazard can be made from the results of such tests, the choice of appropriate comparisons, such as ambient air, are discussed. The advantages and limitations of such systems are considered. Some research needs for the application of bioassays to industrial monitoring are also discussed.