Inhibition of Growth, Synthesis, and Permeability in Neurospora crassa by Phenethyl Alcohol

Lester, Gabriel (Reed College, Portland, Ore.). Inhibition of growth, synthesis, and permeability in Neurospora crassa by phenethyl alcohol. J. Bacteriol. 90: 29-37. 1965.-Inhibition of the growth of Neurospora crassa in still culture was detected at 0.05% and was complete at a level of 0.2% phenethyl alcohol (PEA). Benzyl alcohol was less inhibitory, and 3-phenyl-1-propanol and phenol were more inhibitory, than PEA; benzylamine and phenethylamine were less inhibitory than the analogous hydroxylated compounds. Inhibition by PEA was not reversed by synthetic mixtures of purines and pyrimidines or vitamins, or by casein digests, yeast extract, or nutrient broth. The germination of conidia was inhibited by PEA, but after an exposure of 8.5 hr no loss of viability was observed. The addition of PEA to growing shake cultures caused a simultaneous inhibition of growth and of the syntheses of ribonucleic and deoxyribonucleic acids and protein; the relationships of these compounds to mycelial dry weight and to one another were constant in growing mycelia, and PEA did not significantly affect these relationships. PEA partially inhibited the uptake of glucose, but severely restricted the accumulation of l-leucine, l-tryptophan, or alpha-aminoisobutyric acid in germinated conidia. The efflux of alpha-aminoisobutyric acid from germinated conidia was somewhat enhanced by PEA, but this effect was not so pronounced as the (complete) inhibition of alpha-aminoisobutyric acid accumulation by PEA. It is suggested that PEA affects primarily the initial influx of alpha-aminoisobutyric acid rather than the subsequent retention of alpha-aminoisobutyric acid.

Prevalence of anthelmintic resistant cyathostomes on horse farms

OBJECTIVE

To determine prevalence of anthelmintic resistance in cyathostome nematodes of horses in the southern United States.

DESIGN

Cross-sectional study.

ANIMALS

786 horses on 44 farms and stables in Georgia, South Carolina, Florida, Kentucky, and Louisiana.

PROCEDURE

Fecal egg count (FEC) reduction tests were performed on 44 large farms and stables. Horses on each farm were treated with an oral paste formulation of fenbendazole, oxibendazole, pyrantel pamoate, or ivermectin at recommended label dosages. A mixed linear model was fitted to the percentage reduction in FEC, accounting for differences among farms, states, ages, treatments, and treatment by state interactions.

RESULTS

By use of a conservative measure of resistance (< 80% reduction), the percentage of farms with anthelmintic-resistant cyathostomes was 97.7%, 0%, 53.5%, and 40.5% for fenbendazole, ivermectin, oxibendazole, and pyrantel pamoate, respectively. Mean percentage reductions in FEC for all farms were 24.8%, 99.9%, 73.8%, and 78.6% for fenbendazole, ivermectin, oxibendazole, and pyrantel pamoate, respectively. Pairwise contrasts between states for each treatment revealed that in almost all instances, there were no significant differences in results between states.

CONCLUSIONS AND CLINICAL RELEVANCE

The prevalence of resistance found in this study was higher than that reported previously, suggesting that anthelmintic resistance in equine cyathostomes is becoming a major problem. Furthermore, data from these 5 southern states, which are geographically and physiographically distinct, were remarkably similar. This suggests that drug resistance in cyathostomes is highly prevalent throughout the entire southern United States and probably nationwide.

On-farm and postharvest processing sources of bacterial contamination to melon rinds

Multistate and international foodborne illness outbreaks, particularly involving cantaloupe and often involving rare Salmonella spp., have increased dramatically over the past 13 years. This study assessed the sources and extent of melon rind contamination in production fields and at processing and packing facilities. In the spring of 1999, cantaloupe (Cucumis melo L. [reticulatus group] cv. Cruiser) sampled from two sites in the Rio Grande River Valley showed that postharvest-processed melon rinds often had greater plate counts of bacterial contaminants than field-fresh melons. Cantaloupe in the field had 2.5 to 3.5 log CFU g(-1) rind total coliforms by aerobic plate counts, whereas washed melons had 4.0 to 5.0 log CFU g(-1). In the fall of 1999, coliforms on honeydew melons (C. melo [inodorous group] cv. Honey Brew) ranged from 2.6 to 3.7 log CFU g(-1) after processing, and total and fecal coliforms and enterococci never fell below 2.5 log CFU g(-1). A hydrocooler at another site contaminated cantaloupe rinds with up to 3.4 log CFU g(-1) total and fecal enterococci; a secondary rinse with chlorinated water incompletely removed these bacteria. Sources of coliforms and enterococci were at high levels in melon production soils, especially in furrows that were flood irrigated, in standing water at one field, and in irrigation water at both sites. At one processing facility, wash water pumped from the Rio Grande River may not have been sufficiently disinfected prior to use. Because soil, irrigation water, and process water were potential sources of bacterial contamination, monitoring and management on-farm and at processing and packing facilities should focus on water quality as an important control point for growers and packers to reduce bacterial contamination on melon rinds.

Effect of timing and route of administration of furosemide on pulmonary hemorrhage and pulmonary arterial pressure in exercising thoroughbred racehorses

OBJECTIVES

To examine effect of pre-exercise administration of furosemide (FUR) on mean pulmonary arterial pressure (PAP) during work and RBC concentration in bronchoalveolar lavage fluid (BALF) collected 40 minutes after exercise.

ANIMALS

10 adult Thoroughbreds.

PROCEDURE

A modified 10 X 10 crossover design comprising 10 horses during 10 weeks was used. Each horse received each of 5 treatments twice. Treatment structure included a control plus a 2 X 2 factorial and consisted of the following: A, control; B, FUR, 250 mg, IV, 30 minutes before exercise; C, FUR, 250 mg, IV, 240 minutes before exercise; D, FUR, 250 mg, nebulized, 30 minutes before exercise; and E, FUR, 250 mg, nebulized, 240 minutes before exercise. Mean PAP data were collected, and each horse, after a 500-m warm-up, was galloped at maximal speed for 1,600 m. BALF RBC concentration was determined by hemocytometer.

RESULTS

Interaction between treatment method and time of administration was significant (P = 0.04). Treatment B resulted in significantly (P = 0.01) lower BALF RBC concentration than did treatment C. Only BALF RBC count after treatment B was significantly lower than the control value. Horses that received FUR IV had significantly lower peak mean PAP than did those that received the drug by nebulization, regardless of administration time. Only treatment B resulted in peak mean PAP that was significantly lower than that of control. Exercise time was not influenced by treatment.

CONCLUSIONS

FUR, administered IV 30 minutes before exercise, significantly reduced peak mean PAP and BALF RBC concentration.

State disparities in the diagnosis and placement of pupils with learning disabilities

We investigated the hypothesis that interstate disparities in the diagnosis of pupils with learning disabilities (LD) are more strongly correlated with demographic and sociopolitical factors than with the biological prevalence of the disability. We also investigated the relationship of these factors to placement practices. Thirteen independent variables representing state characteristics were simultaneously regressed against each of seven static dependent variables, measuring diagnostic and placement practices in 1989, and two dynamic dependent variables, measuring changes in practices between 1976 and 1989. Results of the regression indicated that although demographic and sociopolitical factors explained none of the total prevalence of the four most common physical disabilities (adjusted R2[R2] = 0), they did explain to a moderate degree the state prevalence of LD (R2 ranged from .15 to .28), and were more predictive still depending on measure of LD prevalence. Moreover, these same factors strongly predicted the extent to which states mainstreamed their pupils (R2 = .59) and the size of the nonmainstreamed cognitively disabled (LD and educable mentally retarded) population (R2 = .56).

Vitamin D levels in children with cystic fibrosis

Serum levels of the important hormone 1,25-dihydroxyvitamin D (1,25-diOHD, calcitriol) have not been extensively evaluated in patients with cystic fibrosis (CF) during the critical period of skeletal growth and development. This study was a cross-sectional, observational assessment of 25-hydroxyvitamin D (25-OHD, calcidiol) and 1,25-diOHD levels in 54 patients with CF. The patients' ages ranged from 4.9 years to 19.5 years (mean, 11.0 years). Levels were correlated with pulmonary function tests, chest x-ray scores, height and weight Z scores, skinfold percentiles, CF genotype, serum chemistries, and use of a vitamin supplement. Levels were compared with those in more than 160 other pediatric patients living in the same region, and all assays were done in the same laboratory. Despite low-normal levels of the 25-OHD precursor, there was a high prevalence of low (18%) and marginal (18%) levels of 1,25-diOHD. None of the various parameters examined correlated with either 25-OHD or 1,25-diOHD levels. The cause, clinical significance, and treatment of low levels of this important hormone in children with CF warrant further study.

Bone mineral content at three sites in normal perimenopausal women

Bone mineral content (BMC) in 217 healthy white women between the ages of 40 and 55 years was measured using single- and dual-photon absorptiometry. The sites measured included the distal radius, midradius, proximal femur, and lumbar spine. The relationship between BMC and age was constant over the age range studied when the confounding effect of menopause was controlled. Women with low body mass indices (BMIs) had significantly lower BMC than women with average or greater than average BMIs. More active women had higher BMC than less active women at both appendicular and axial sites. A trend suggesting that women with higher calcium intake may have higher BMC was statistically significant only at the midradial site. A trend of postmenopausal women having lower BMC than pre- or perimenopausal women was also statistically significant only at the midradial site. Only modest correlations were found between the various sites. These correlations are too weak to allow accurate clinical predictions of BMC at axial sites from the BMC at an appendicular site in individual patients.

Acquired postganglionic cholinergic dysautonomia: case report and review of the literature

An 8-year-old girl with acute abdominal pain had cholinergic autonomic dysfunction. There have been only four patients with acquired postganglionic cholinergic dysautonomia described in the literature. The characteristic clinical features are atony of the bowel and bladder, lack of tears, saliva, and sweat, internal ophthalmoplegia, and normal adrenergic functions. Special studies for autonomic nervous function help in confirming this diagnosis. The exact pathogenesis of the disorder is still not clear. This case demonstrates successful treatment with bethanechol chloride.

Distractibility, intensity of reaction, and non-nutritive sucking

Parents of 184 children were asked to rate their children on distractibility, intensity of reaction, feeding, teething, and non-nutritive sucking habits. Non-distractible children were significantly more likely to be long-term non-nutritive suckers. Ratings of distractibility and intensity of reactions were significantly related. No sex differences appeared on any of the variables.

Isolation and characterization of low-kynureninase mutants of Neurospora crassa

Two kynureninase activities are known in Neurospora crassa, one of which (kynureninase I) is inducible, the other (kynureninase II) being constitutive. A method is described for the isolation of low-kynureninase mutants of N. crassa. When grown on an inducer, the mutants show significantly less kynureninase I activity compared with wild type, whereas constitutive kynureninase II activity is unaffected. Since a low level of kynureninase I activity remains in the mutants examined, the mutations may be in a regulatory gene or genes. Other experiments are described concerning the molecular weights of the two enzymes and the intracellular localization and specificity of kynureninase II.

End-product regulation of the tryptophan-nicotinic acid pathway in Neurospora crassa

The regulation of the tryptophan-nicotinic acid pathway in Neurospora crassa was examined with mutants (nic-2, nic-3) which require nicotinamide for growth. The accumulation of N-acetylkynurenin and 3-hydroxyanthranilic acid by these mutants served to estimate the level of function of the early reactions in the pathway. In still cultures, maximal accumulation occurred with media containing growth-limiting amounts of nicotinamide; the accumulation of intermediates was almost negligible with nicotinamide in excess. Only nicotinamide and closely related compounds which also supported the growth of these mutants inhibited the accumulation of intermediates. The site of inhibition was assessed to be between tryptophan and kynurenin (or N-acetylkynurenin). The synthesis of N-acetylkynurenin was examined in washed germinated conidia suspended in buffer; the level of N-acetylkynurenin-synthesizing activity was inversely related to the concentration of nicotinamide in the germination medium. The addition of large amounts of nicotinamide to suspensions of germinated conidia did not affect their N-acetylkynurenin-synthesizing activity. Formamidase activity, kynurenin-acetylating activity, and gross tryptophan metabolism in germinated conidia was not influenced by the concentration of nicotinamide in the germination medium. The results obtained indicate that the site of inhibition by nicotinamide is the first step in the pathway, the tryptophan pyrrolase reaction. The data are interpreted as nicotinamide or a product thereof, such as nicotinamide adenine dinucleotide, acting as a repressor of the formation of tryptophan pyrrolase in N. crassa.

Regulation of tryptophan biosynthetic enzymes in Neurospora crassa

The formation of enzymatic activities involved in the biosynthesis of tryptophan in Neurospora crassa was examined under various conditions in several strains. With growth-limiting tryptophan, the formation of four enzymatic activities, anthranilic acid synthetase (AAS), anthranilate-5-phosphoribosylpyrophosphate phosphoribosyl transferase (PRAT), indoleglycerol phosphate synthetase (InGPS), and tryptophan synthetase (TS) did not occur coordinately. AAS and TS activities began to increase immediately, whereas PRAT and InGPS activities began to increase only after 6 to 12 hr of incubation. In the presence of amitrole (3-amino-1,2,4-triazole), the formation of TS activity in a wild-type strain was more greatly enhanced than were AAS and InGPS activities. With a tr-3 mutant, which ordinarily exhibits an elevated TS activity, amitrole did not produce an increase in TS activity greater than that observed on limiting tryptophan. With tr-3 mutants, the increased levels of TS activity could be correlated with the accumulation of indoleglycerol in the medium; prior genetic blocks which prevented or reduced the synthesis of indoleglycerol also reduced the formation of TS activity. The addition of indoleglycerol to cultures of a double mutant (tr-1, tr-3) which could not synthesize indoleglycerol markedly stimulated the production of TS activity but not PRAT activity; the production of TS activity reached the same level with limiting or with excess tryptophan. A model explaining these and other related observations on enzyme formation in N. crassa is proposed.

Properties of an extracellular -galactosidase secreted by Neurospora crassa

An extracellular beta-galactosidase with an activity optimum at about pH 4 was found to occur in the filtrates of Neurospora crassa strain 74A when this mold was grown on certain sugars. This activity accounted for a substantial portion of the beta-galactosidase activity in the culture. The beta-galactosidase in the medium appeared to be a secreted, extracellular enzyme, not a product of cell lysis. The extracellular activity was found to have physical and kinetic properties similar to those of an intracellular beta-galactosidase previously found in Neurospora. Some conditions for the production and concentration of the enzyme are described.

Disconfirmation of an hypothesis about the Mueller-Lyer illusion

Gregory's (1966) explanation of the Mueller-Lyer illusion was used to derive the prediction that the illusion should be less strong when O is distant from the figures than when he is close. 12 Os were tested when far from and when close to the figures. The results did not confirm the prediction.

Comparison of five methods of presenting the Rod-and-Frame test

Fifty undergraduate women were tested with 5 versions of the Rod-and-frame Test. One method yielded a significantly smaller variance than any other. The same method also gave a smaller frame effect than has previously been noted for female Ss.

In vivo regulation of intermediate reactions in the pathway of tryptophan biosynthesis in Neurospora crassa

The in vivo regulation of intermediate reactions in the pathway of tryptophan synthesis in Neurospora crassa was examined in a double mutant (tr-2, tr-3) which lacks the functions of the first and last enzymes in the pathway from chorismic acid to tryptophan. The double mutant can convert anthranilic acid to indole and indole-3-glycerol, and the production of these indolyl compounds by germinated conidia was used to estimate the activity of the intermediate enzymes in the pathway. Indole-synthesizing activity was maximal in germinated conidia obtained from cultures in which the levels of l-tryptophan were growth-limiting; the formation of this activity was markedly repressed when the levels of l-tryptophan exceeded those required for maximal growth. d-, 5-methyl-dl-, and 6-methyl-dl-tryptophan were less effective than l-tryptophan, and 4-methyl-dl-tryptophan, tryptamine, and indole-3-acetic acid were ineffective in repressing the formation of indole-synthesizing activity; anthranilic acid stimulated the formation of indole-synthesizing activity. Preformed indole-synthesizing activity was strongly and specifically inhibited by low levels of l-tryptophan; several related compounds were ineffective as inhibitors. These results suggest that, in addition to repression, an end product feedback inhibition mechanism is operative on an intermediate enzyme(s) in tryptophan biosynthesis. The relation of these results to other in vivo and in vitro studies and to general aspects of the regulation of tryptophan biosynthesis in N. crassa are discussed.

The Rod-and-Frame test: some comments on methodology

The technique of the Rod-and-frame Test as used by most psychologists is criticized for difficulties in control of head position, starting position effects, control readings, and the effect of instructions. Differences in results reported with Witkin's method and with other methods are discussed.

Studies on insulin biosynthesis. Subcellular distribution of leucine-H3 radioactivity during incubation of goosefish islet tissue

Islet tissue from the goosefish (Lophius piscatorius) was incubated in the presence of leucine-H(3). The tissue was then separated into subcellular fractions and the radioactivity determined in total acid alcohol-soluble proteins, insoluble proteins, and insulin. At any time, microsomal protein had a higher activity than secretion granule protein. Pulse-chase experiments further suggest the microsomes as primary sites of protein synthesis. The data are evidence for microsomal synthesis of insulin and for its subsequent transfer into the secretion granules.

Genetic control of amino acid permeability in Neurospora crassa

Lester, Gabriel (Reed College, Portland, Ore.). Genetic control of amino acid permeability in Neurospora crassa. J. Bacteriol. 91:677-684. 1966.-Strains of Neurospora crassa resistant to 4-methyltryptophan (4-MT) were isolated from populations of conidia exposed to ultraviolet light. In genetic crosses, 4-MT resistance behaved as a single-gene difference. Resistance to 4-MT could not be attributed to a relaxation of control of the formation or the activity of the enzymes of tryptophan biosynthesis. Growth studies involving tryptophan auxotrophs carrying the aberrant mt gene and uptake studies with normal and 4-MT-resistant strains showed that 4-MT resistance could be attributed to an inability of 4-MT-resistant strains to take up tryptophan and its methyl analogues. The mt gene is not specific for tryptophan; strains resistant to 4-MT are also resistant to ethionine, and they have a markedly reduced ability to take up serine, leucine, and alpha-aminoisobutyric acid. No difference was observed between strains carrying either mt allele in their ability to take up glucose; also, the uptake of anthranilic acid or of indole was not sufficiently impaired by the aberrant mt gene to prevent these tryptophan precursors from satisfying the nutritional requirement of certain tryptophan auxotrophs. The role of the mt gene in determining the permeability of N. crassa to amino acids is discussed.