Carbohydrate Metabolism in Leaf Meristems of Tall Fescue : II. Relationship to Leaf Elongation Rates Modified by Nitrogen Fertilization

Our objective was to examine alterations in carbohydrate status of leaf meristems that are associated with nitrogen-induced changes in leaf elongation rates of tall fescue (Festuca arundinacea Schreb.). Dark respiration rates, concentrations of nonstructural carbohydrates, and soluble proteins were measured in leaf intercalary meristems and adjacent segments of elongating leaves. The two genotypes used differed by 43% in leaf elongation rate. Application of high nitrogen (336 kilograms per hectare) resulted in 140% higher leaf elongation rate when compared to plants receiving low nitrogen (22 kilograms per hectare). Leaf meristems of plants receiving high and low nitrogen had dark respiration rates of 5.4 and 2.9 microliters O(2) consumed per milligram structural dry weight per hour, respectively. Concentrations of soluble proteins were lower while concentrations of fructan tended to be slightly higher in leaf meristems of low-nitrogen plants when compared to high-nitrogen plants. Concentrations of reducing sugars, nonreducing sugars, and takadiastase-soluble carbohydrate of leaf meristems were not affected by nitrogen treatment. Total nonstructural carbohydrates of leaf meristems averaged 44 and 39% of dry weight for low- and high-nitrogen plants, respectively. Within the leaf meristem, approximately 74 and 34% of the pool of total nonstructural carbohydrate could be consumed per day in high- and low-nitrogen plants, respectively, assuming no carbohydrate import to the meristem occurred. Plants were able to maintain high concentrations of nonstructural carbohydrates in leaf meristems despite a 3-fold range in leaf elongation rates, suggesting that carbohydrate synthesis and transport to leaf intercalary meristems may not limit leaf growth of these genotypes.

Benzidine dihydrochloride: risk assessment

Benzidine, recognized as a bladder carcinogen in man and as a liver carcinogen in experimental animals, is the chemical basis of as many as 200 commercial dyes. Physiological processes can metabolize these dyes to release benzidine, thereby creating a potential exposure hazard. To assess this hazard, both sexes of F1 hybrid (genetically homogeneous) and monohybrid (genetically heterogeneous) mice from a BALB/c male and C57BL/6 female cross were exposed for their respective lifespans to benzidine dihydrochloride in their drinking water at concentrations of 0, 30, 40, 60, 80, 120, and 160 ppm for males, and 0, 20, 30, 40, 60, 80, and 120 ppm for females. Animals were removed from the study when they were dead or moribund. This study was terminated after 33 months of exposure. Using the endpoint of hepatocellular adenomas and carcinomas, the Armitage Doll multistage model was used to describe the tumor rates in the experimental dose range and to obtain the upper confidence level on tumor rates. Linear interpolation was used between zero dose and the upper confidence level of the lowest experimental dosage for predicting potential low dose tumor rates. Dose-response effects on body weight, survival, and liver neoplasms were noted in both stocks. For each of the endpoints, the females were more susceptible than males and the F1 (homogeneous) stock was more susceptible than the monohybrid cross (heterogeneous). The calculated virtually "safe" dose predicted to produce less than one per million F1 female mice with a liver tumor is 0.045 ppb. One part per billion of benzidine dihydrochloride in the drinking water of these mice is estimated to produce liver tumors in less than 2.23 mice per 100,000 population.

Sex and strain differences in the developmental activity profile of the rat tested over clean vs home cage bedding

In the first of two experiments, CD rat litters were used to characterize activity patterns obtained in a size-adjustable, single photodetector chamber. Beginning on postnatal Day 10 or 12, pups were tested repeatedly over clean bedding (C) or over bedding removed from each pup's home cage (HC). In C rats of both sexes and in HC females, short-term activity levels peaked on Day 16. However, HC males displayed an earlier and even greater elevation in activity from Day 12 to 16. This overall pattern was found in rats tested either every second or fourth day. In the second experiment, Long-Evans pups were assigned to each testing condition (C vs HC) and activity measured beginning on Day 12. Peak levels were seen in all Long-Evans rats on Day 16 and only females showed significant alterations as a function of bedding condition. When overall activity levels of the two strains were compared, significant differences were found on Days 12, 24, 30, and 120 in males, and 12, 24, and 30 in females. Significant differences between strains in activity as a function of bedding condition were found in males on Days 12, 20, 24, and 120 and in females on Days 12, 30, and 60. These data confirm the generality of a developmental hyperactivity phase in isolated juvenile rats. However, different patterns of hyperactivity were found in male vs female rats across strains. CD males were more active in the presence of HC olfactory cues, while in Long-Evans rats, female activity was affected more by bedding condition.

Benzidine dihydrochloride: toxicological assessment in mice during chronic exposures

Although benzidine is recognized as a bladder carcinogen in humans and a liver carcinogen in laboratory animals, its toxicological effects appear to be extended to several other endpoints. This economically important chemical is the base for over 200 dyes and is used extensively in manufacturing. In a chronic lifespan study lasting 33 months, both sexes of F1 hybrid (genetically homogeneous) and monohybrid cross (genetically heterogeneous) mice from BALB/c male and C57BL/6 female crosses were exposed to benzidine dihydrochloride in their drinking water at concentrations of 0, 20, 30, 40, 60, 80, and 120 ppm for the females, and 0, 30, 40, 60, 80, 120, and 160 ppm for males. Animals were removed from the study when they were dead or moribund. In addition to hepatocellular carcinomas, there were several other toxicological end-points identified that appeared to be related to the administration of benzidine. Dose-response trends were noted for pigmentation of the spleen, hepatic cytological alterations, hyperplasia of the bile ducts, megakaryocytosis of the bone marrow, vacuolization of the brain, adenoma of the Harderian gland, atrophy of the ovaries, and angioma of the uterus. Also, dose-related effects were noted with respect to time to lung tumor and time to mortality due to reticulum-cell sarcomas.

Photosynthesis in Tall Fescue : IV. Carbon Assimilation Pattern in two Genotypes of Tall Fescue Differing in Net Photosynthesis Rates

We previously reported that the net photosynthetic rate of a decaploid genotype (I-16-2) of tall fescue (Festuca arundinacea Schreb.) was 32 to 41 versus 22 milligrams CO(2) per square decimeter per hour in a hexaploid genotype (V6-802) (Randall, Nelson, Asay Plant Physiol 59: 38-41). The high rate was later correlated with increases in total ribulose 1,5-bisphosphate carboxylase protein (17%) and activity (27%) (Joseph, Randall, Nelson Plant Physiol 68: 894-898). This report characterizes photosynthesis with respect to light saturation and early products of photosynthesis in an attempt to identify regulatory metabolic site(s) in these two genotypes. Analysis of the early products of photosynthesis indicated that both genotypes fixed CO(2) via the Calvin-Benson cycle with phosphoglyceric acid as the initial primary product. Both genotypes had similar (14)C-labeled intermediates. Sucrose was the primary sink of (14)CO(2) assimilation. After 10 min of (14)CO(2) assimilation with attached leaves, sucrose accounted for 89% (decaploid) and 81% (hexaploid) of the total (14)C incorporated. In 10 min, this amounted to 1.3 (decaploid) and 0.8 (hexaploid) mumol [(14)C]sucrose formed g fresh weight(-1) and reflected the observed differences in photosynthetic rates. There was limited labeling of starch (1%) and fructan (1%). Results of total nonstructural carbohydrates and P(i) analysis also demonstrated sucrose was the predominant carbohydrate in fescue leaves. Quantitative differences in sucrose and P(i) between the two genotypes may reflect changes in partitioning and this possibility is discussed.

Impotence in medical clinic outpatients

One thousand one hundred eighty men in a medical outpatient clinic were screened as to the presence of impotence. Four hundred one men (34%) were impotent, and of those, 188 (47%) chose to be examined for their problem. After a comprehensive evaluation the following diagnoses were obtained: medication effect, 25%; psychogenic, 14%; neurological, 7%; urologic, 6%; primary hypogonadism, 10%; secondary hypogonadism, 9%; diabetes mellitus, 9%; hypothyroidism, 5%; hyperthyroidism, 1%; hyperprolactinemia, 4%; miscellaneous, 4%; and unknown causes, 7%. The mean age of the impotent patients was 59.4 years, and the prevalence of alcoholism was 7%. Luteinizing hormone, follicle-stimulating hormone, testosterone, thyroxine, triiodothyronine (T3), T3 resin uptake, and prolactin studies were necessary to diagnose individual cases. We conclude that erectile dysfunction is a common and often overlooked problem in middle-aged men followed in a medical clinic.

Ultrasonic vocalizations as diagnostic tools in studies of developmental toxicity: an investigation of the effects of prenatal treatment with methylmercuric chloride

Ultrasonic vocalizations were recorded during two tasks from four groups of neonatal CD rat pups. Groups 0, 2, 4 and 6 were the offspring from pregnant dams treated with 0, 2, 4 or 6 mg/kg methylmercuric chloride by gavage on gestation day 7. On the day of birth, Day 1, litters were randomly culled to 8 pups (4 males, 4 females). The pups were weighed on Days 1, 7, 14, 21 and 30, and no weight differences due to treatment were observed. At 5, 7, 9 and 11 days of age, ultrasonic vocalizations were recorded from the animals for 1 minute. Individual animals were placed in a small test chamber containing either soiled home cage bedding or clean bedding material. Half of the pups in each litter were tested in each "odor" condition, and the rate and duration of the vocalizations were measured for 1 minute. On days 8 and 9, pups were tested on a negative geotaxis incline during which time vocalizations were recorded. In both the "odor" and negative geotaxis tests, methylmercuric chloride affected vocalization rates in a nonlinear dose-response fashion. Regardless of treatment group, the pups vocalized at a higher rate and for a longer duration in the clean than in the soiled bedding test condition. These data showed the variability of the ultrasonic vocalization responses to be smallest for the animals tested at 11 days of age in the clean bedding condition. The results of this study suggest that the value of ultrasonic calls as dependent measures of toxicity may be strengthened by the use of multiple stimulus conditions in order to elicit a graded response pattern. This would facilitate the interpretation of potential nonlinear dose-response effects.

Blood flow during pregnancy in the rat: I. Flow patterns to maternal organs

Normal blood flow patterns to several maternal organs were characterized in individual CD rats, nonpregnant (NP) or on day 6, 7, 8, 10, 11, 12, 13, 16, 18, or 20 of gestation using the radioactive microsphere technique. Weights and flow values were determined for several uterine tissue samples as well as maternal organs. No significant changes were found in blood flow to the stomach, spleen, and urinary bladder of these animals. There also were no remarkable changes as pregnancy progressed in blood flow to the lungs, suggesting that no marked arterial-venous shunting occurs in maternal placental tissues over gestation. Slight but consistent decreases in absolute (ml/min) and relative (ml/min/g tissue) blood flow to the brain were noted, and percent cardiac output (CO) was significantly decreased on all days of gestation except day 7. Complex changes were observed in blood flow to the kidneys, liver, adrenals, and heart. Absolute flow to the kidneys and liver reached maximum values on day 11, although percent CO delivered to both organs was consistently reduced throughout gestation. Absolute flow to the heart and adrenals peaked on day 13 and days 11-12, respectively. Absolute flow to the ovaries increased nearly 5-fold from the NP state (0.36 +/- 0.11) to day 20 of pregnancy (1.61 +/- 0.33). Interlitter differences in ovarian blood flow during midgestation were found to be a result of differences in litter size and distribution of embryo/fetuses between the two uterine horns. The fact that the majority of changes observed in maternal organ flow coincide with placental development, rapid augmentation of total uterine flow, and/or maternal hormonal changes suggests that these patterns may be important indicators of the dynamic physiology of pregnancy.

Blood flow during pregnancy in the rat: II. Dynamics of and litter variability in uterine flow

Normal blood flow patterns were characterized in individual CD rats, nonpregnant (NP) or on day 6, 7, 8, 10, 11, 12, 13, 16, 18, or 20 of gestation using the radioactive microsphere technique. Five animals were evaluated at each stage of pregnancy. Weights and flow values were determined for several maternal organs and uterine tissue samples. Embryo/fetal (E/F) sex was determined from day 11 on by measuring the prevalence of nuclei with sex chromatin in amnion smears. There was a marked increase in absolute flow to the uterus and all uterine contents during gestation (0.28 +/- 0.13 ml/min to the NP, diestrous uterus; 9.07 +/- 0.97 ml/min on day 20 of pregnancy). However, relative blood flow (ml/min/g tissue) decreased by day 20 to one-third NP values. Thus, though blood flow greatly increased, it did so at a rate lower than total tissue growth (including the uterus, placental tissues, and the E/F itself). There was a rapid redistribution of blood flow from the decidua parietalis (DEC) to the chorioallantoic placenta (CAP) on days 11-13, with nearly equal flow being delivered to the CAP and DEC of the "average" embryo on day 12 of gestation. By day 16 the DEC functionally had atrophied, and nearly 100% of the flow was delivered to the CAP. Male E/Fs tended to weigh more than female; however, these differences were statistically significant only on days 13, 18, and 20. E/F sex was not found to be strongly related to any of the variables evaluated in this study except E/F weight. Significant interlitter variability in E/F weight and blood flow consistently was observed at all gestational stages. Differences in litter size and E/F distribution within the two uterine horns did not account for the majority of this variability.

Ploidy effects on anatomy and gas exchange of tall fescue leaves

A growth chamber study was designed to interpret differences in CO(2) exchange rate (CER) and leaf diffusive resistance among 4X, 6X, 8X, and 10X ploidy levels of tall fescue (Festuca arundinacea, Schreb). Mesophyll cell size, stomatal density, number of major and minor veins, and bundle cap size of leaf blades were evaluated. Diffusive resistance tended to decrease and CER to increase with increasing ploidy level. Mean stomatal density decreased from 43.6 per square millimeter to 30.6 per square millimeter as ploidy level increased from 4X to 8X. The 10X ploidy level exhibited the highest stomatal density, 47.2 per square millimeter. Major veins decreased from a mean of 14.2 to 10.2, and minor veins increased from a mean of 4.2 to 6.6, per leaf blade as ploidy increased from 4X to 10X. Total number of veins decreased significantly from a mean of 18.4 to 15.7 as ploidy increased from 4X to 8X.Length and width of mesophyll cells tended to increase as ploidy increased from 4X to 8X, but then decreased again at 10X. The number of cells in the bundle cap showed no trend among ploidy levels. Estimated volume of mesophyll cells increased six times between the 4X and the 6X level while chromosome number of nuclear DNA per cell increased only 50%. However, increases in estimated cell volume were proportional to chromosome number as ploidy increased from 6X to 8X. The relationship between cell volume and chromosome number at 10X was intermediate between that at 4X and 6X or 8X.Differences in stomatal density and diffusive resistance did not fully account for the ploidy effect on CER. Further mesophyll cell volume was positively related to CER, a factor contrary to earlier experiments.

Correlation of liver tumor morphology and weight to incidence of pulmonary metastases in the mouse

Benzidine dihydrochloride administered in water at 0, 30, 60, 120, 200 or 400 ppm to 1664 mice induced a total of 368 hepatocellular carcinomas, of which 34 or 9.2% metastasized to the lungs. Liver tumors which were larger and heavier were more prone to metastasize and all that metastasized contained areas of prominent trabecular formation.

An illness-death model for the study of the carcinogenic process using survival/sacrifice data

A semi-Markov model for describing the development of a specific type of tumor which is followed by death from that tumor is proposed. This provides a method for investigating the observable phases of tumor development, when time to appearance of tumor in individual animals is not directly measurable. Parameters of the model are estimated by the method of maximum likelihood. The modeling and estimation procedures are illustrated with liver tumors induced by benzidine dihydrochloride in mice, and inferences with respect to strain, sex and dose differences are made.

Commercial laboratory animal diets: toxicant and nutrient variability

A commercial rodent feed was analyzed for a series of nutrients and potential contaminants during a 5-yr period. Annual average Cu and vitamin A concentrations were generally at least 12% lower than the approximate concentrations listed by the manufacturer, whereas Ca, protein, and vitamin B1 were within +/- 5% and fat and Zn within +/- 8% of the manufacturer's specifications. Frequently, Se was found at concentrations at which it has been shown to interact with the process of chemical carcinogenesis. DDT, dieldrin, Cd, and Pb were occasionally close to concentrations known to have biological effects.

A review and critique of social skills training with schizophrenic patients

The literature dealing with social skills training of schizophrenic patients indicates that topographical features and self-reports of anxiety and discomfort can be changed for the better by social skills training. Unfortunately, these changes do not occur for every patient and, when they do occur, often do not generalize to new situations. Research must be directed to determining the interaction between patient characteristics and training procedures as they affect outcome. The scope of the procedures must also be expanded if meaningful changes in patients' quality of life are to be effected.

Accuracy of birth certificate data for detecting facial cleft defects in Arkansas children

A comparison of facial cleft defects reported on birth certificates during the period 1943 to 1974 that were reported on birth certificates was made with records maintained by the Arkansas Crippled Childrens Services (CCS). A total of 506 cases were reported of which 331 (65%) were recorded on the birth certificate. Moreover, the accuracy of the reporting was not good. Only 243 (48%) cleft malformations were correctly classified on the birth certificate. Birth certificate information is an inadequate measure of the true facial cleft occurrence in Arkansas. Caution must be exercised when this data source is used in epidemiological surveys because over one-third of such defects were not recorded. These findings serve to reemphasize the national need to improve the quality of such vital health statistics sources.

Statistical analysis of teratologic data: problems and advancements

A large scale replicated dose-response teratology study of 2,4,5-T was done in mice. Variability and variance of fecundity parameters and fetotoxicity endpoints are discussed. Another study on rats indicated less variation among teratologic endpoints than in mice. Calculations for the number of animals in strains of mice and rats needed to detect a 5 percent and 10 percent reduction in mean fetal weight or increase in resorptions are given. We concluded that at least 3 replicates with appropriate numbers of pregnant animals are needed to estimate variance for comparison among laboratories or among species. The utility of these calculations for standardizing teratologic studies is discussed.

DIALLEL AND PATH COEFFICIENT ANALYSIS OF TALL FESCUE (FESTUCA ARUNDINACEA) REGROWTH UNDER CONTROLLED CONDITIONS

Relationships among leaf elongation rate, leaf width, leaf area expansion rate, number of tillers/plant, and net CO2 exchange (NCE) with total forage yield/plant of tall fescue, Festuca arundinacea Schreb., were studied in a controlled environmental chamber. Among progeny of a 6 × 6 diallel, number of tillers/plant was correlated highly significantly (1% level) with total forage yield/plant (r = 0.697). Path coefficient analyses showed that both tillers/plant and yield/tiller had large positive direct effects on total yield/plant. Utilizing a diallel analysis it was found that additive genetic effects were most important for all traits except for NCE. Progenies did not differ significantly for NCE. Nonadditive genetic effects, although of less magnitude than additive effects, were also found to be important for number of tillers/plant and yield/tiller. Highest broad sense heritabilities were found for number of tillers/plant, yield/tiller, and yield/plant with values of 69, 66, and 66%, respectively

Ribulose bisphosphate carboxylase: altered genetic expression in tall fescue

A decaploid tall fescue (Festuca arundinacea Schreb) genotype has been found which exhibits net photosynthetic rates of 32 to 41 mg CO(2)/dm(2).hour as opposed to a mean of 22 mg CO(2)/dm(2).hour for 10 hexaploid genotypes. The decaploid genotype exhibited a ribulose 1,5-bisphosphate (RuBP) carboxylase specific activity 1.3- to 2-fold higher than typical tall fescue genotypes. Specific activities of photorespiratory enzymes and nitrate reduction enzymes were lower in the decaploid than the hexaploid genotypes. Results suggest that genetic expression of RuBP carboxylase activity may have been altered to increase the net photosynthesis rate in the decaploid genotype.