Fermentation of Peptides by Bacteroides ruminicola B14

The maximum growth rate of Bacteroides ruminicola B₁4 was significantly improved when either Trypticase or acetate and C₄-C₅ fatty acids were added to defined medium containing macrominerals, microminerals, vitamins, hemin, cysteine hydrochloride, and glucose. The organism was unable to grow with peptides as the sole energy source, but growth yields from glucose were significantly improved when Trypticase was added to batch cultures containing basal medium, acetate, and C₄-C₅ volatile fatty acids. During periods of rapid growth, very little peptide was deaminated to ammonia, but after growth ceased there was a linear increase in ammonia. Fifteen grams of Trypticase per liter resulted in maximum ammonia production. In glucose-limited chemostats, ammonia production from peptides was inversely proportional to the dilution rate, and 87% of the variation in ammonia production could be explained by retention time in the culture vessel. Chemostats receiving Trypticase had higher theoretical maximum growth yields and lower maintenance energy expenditures than similar cultures not receiving peptide. Cells from the Trypticase cultures contained more carbohydrate, and this difference was most evident at rapid dilution rates. When corrections were made for cell composition and the amount of peptides that were fermented, it appeared that peptide carbon skeletons could be used for maintenance energy. B. ruminicola B₁4 was unable to grow on peptides alone because it was unable to utilize peptides at a fast enough rate to meet its maintenance requirement.     

Generalized Transduction in the Phytopathogen Pseudomonas syringae

Bacteriophages isolated from culture supernatants of Pseudomonas syringae pv. syringae and from sewage transferred various chromosomal genes to P. syringae PS224. Linkage between arginine and tryptophan loci was demonstrated. The number of transductants recovered per milliliter was not altered appreciably by UV irradiation of selected phage isolates. In addition, the presence of the IncP2 plasmid R38 in a P. syringae PS224 arginine auxotroph did not increase the transduction frequency as it does in Pseudomonas aeruginosa. Increasing the multiplicity of infection of transducing phage Pssy15 from 1 to 10 resulted in up to a 10-fold increase in the number of transductants recovered, although the actual transductional frequency remained about the same. Treatment of transduction mixtures with DNase did not affect transductional frequency.     

Ribosomal genes of Neurospora crassa: constancy of gene number in the conidial and mycelial phases, and homogeneity in length and restriction enzyme cleavage sites within strains

We report the results of experiments which, while not specifically designed to study the possibility of rDNA amplification during different developmental stages in the N. crassa life cycle, clearly indicate a relative constancy in the rDNA content of conidia (asexual spores) and mycelial cells. We also report the results of restriction enzyme studies which indicate that the Neurospora rDNA repeat units are homogeneous in length and restriction site pattern within any given Neurospora strain. These results directly contradict the recent report of Dutta et al. (1983), in which the authors concluded that the rDNA of germinating conidia is amplified, relative to mycelia, and that up to 10% of the rDNA units are heterogeneous.     

Relationship of seminal vesicle size and measures of libido in yearling beef bulls

Ninety-five yearling beef bulls were given routine Breeding Soundness Examinations, two libido tests and palpated rectally for internal genital disease and measurement of seminal vesicle size. Finger tips were premeasured, and then used as "glandometers". The bulls were examined at the end of a 140-day performance test. Sixteen lines of breeding were examined including 13 Hereford, 2 Angus and 1 Red Angus. Average age was 384 days and average weight was 961 lbs. Line and breed differences (P<.05) were observed for scrotal circumference, scrotal circumference score and second libido test. Similar differences were observed for SV length (P<.01), depth and volume both (P<.05). There were no significant correlations between seminal vesicle (SV) size and libido scores. There were, however, significant correlations between SV size and scrotal circumference (P<.05), BSE score (P<.01), body weight (P<.01), and semen morphology score (P<.05). Proximal droplets and midpiece abnormalities, respectively, were the most common spermatozoal abnormalities observed in semen from this group of bulls.     

Effect of Glutaraldehyde on the Outer Layers of Escherichia coli

S ummary : Sodium lauryl sulphate (SLS) at pH 3 and 8 lysed cell walls of Escherichia coli. Pretreatment with glutaraldehyde at pH 3 and at pH 8 prevented this lysis. SLS induced maximum lysis of E. coli cells at 40°; pretreatment of cells with glutaraldehyde prevented this lysis also. Electrophoretic studies indicated that glutaraldehyde accumu lated on the surface of E. coli cells more rapidly in acid than in alkaline conditions, and that it blocked amino groups on the surface layer of Bacillus subtilis spores. The relationship of these findings to the bactericidal efficiency of glutaraldehyde in acid and alkaline solution is discussed.     

Quantitative Nasal Culture: a Tool in Antibiotic Research

The use of the quantitative nasal culture was investigated as a means of evaluation of new antimicrobial drugs in man. Cyclacillin was somewhat more active in vitro than penicillin G against penicillin G-resistant organisms. Cyclacillin was highly effective in suppressing staphylococci susceptible to penicillin G in nasal carriers but did not suppress staphylococci resistant to penicillin G. Although in previous studies by others cyclacillin was effective in treating mice infected with penicillin G-resistant staphylococci, in the present studies cyclacillin was not effective in suppressing nasal penicillin G-resistant staphylococci in man at doses which markedly suppressed penicillin G-sensitive organisms.     

Immunological and Biophysical Separation of Dengue-2 Antigens

Antigenic compositions of slowly sedimenting dengue-2 hemagglutinin (SHA) and soluble complement-fixing antigen (SCF) were compared with the virion (rapidly sedimenting hemagglutinin, RHA) by radioimmune precipitation (RIP), RIP inhibition, kinetic neutralization, and neutralization blocking tests with the use of hyperimmune mouse ascitic fluids. RHA and SHA were unable to inhibit completely the RIP of each other by anti-RHA, and neutralization by anti-RHA was not blocked by SHA. This indicated that SHA is serologically related, but not identical, to RHA. SHA differed from RHA in that SHA lacked the “core” polypeptide but contained the two envelope polypeptides. In addition, SHA contained a polypeptide with a molecular weight of 16,500 daltons and a suggestion of several other proteins. These data, when considered with other evidence, suggest that SHA is a special form of “incomplete virus.” SCF was unable to inhibit the RIP of SHA or RHA or to block neutralizing antibodies. Further, anti-SCF did not neutralize RHA or precipitate significant levels of SHA or RHA. Polyacrylamide gel electrophoresis separated SCF from structural polypeptides by molecular size. This evidence suggests that SCF is a nonstructural antigen.     

Probing by aphids in the leaf tissues of resistant and susceptible sugar beet

The probing of Aphis fabae and Myzus persicae in the leaves of sugar beet with inherited resistance or susceptibility to aphids was studied by microscopic examination of samples of whole leaves, prepared after 48 h exposure to adult aphids at approximately three aphids cm^-2.The density of saliva stylet-sheaths left by the aphids (cm^-2) and the proportion reaching phloem differed between sugar beet stocks and were inversely associated. Differences in resistance between stocks could not, however, be related directly to either. All beet stocks examined were probed freely. Seasonal differences in sugar beet grown in the glasshouse affected the proportion of sheaths reaching the phloem, but the differences between beet stocks were similar at all times.The densities of sheaths left by different clones of M. persicae corresponded with the aphids' response to sugar beet as a host plant. Among aphid clones which readily colonize sugar beet, the densities of stylet sheaths which reached phloem suggested that the adults of both A. fabae and M. persicae gained sufficient access to sieve tubes to satisfy their nutritional needs. The phloem of sugar beet from the glasshouse was always within the estimated maximum depth to which the aphids probe; but, in leaves from the field, it appeared that the phloem might be inaccessible to young M. persicae in the sugar beet crop during late summer.

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Zusammenfassung Das Proben von Aphis fabae und Myzus persicae in Blättern von Zuckerrüben mit erblicher Blattlausresistenz bzw.-anfälligkeit wurde untersucht durch mikroskopische Durchmusterung von Speichelscheiden in Proben von ganzen Blatt. Rübenblätter wurden mit genähert drei adulten Läusen cm^-2 besetzt und nach 48 Stunden quergeschnittene Streifen der Blätter in Alkohol fixiert, gefärbt und mit der Unterseite nach oben auf Objektträgern eingeschlossen.23890 Speichelscheiden wurden registriert. Die Dichte der Scheiden von M. persicae (cm^-2) und der Anteil der das Phloem erreichenden Scheiden (SRP) unterschieden sich signifikant zwischen den Rübenstämmen. Bei A. fabae ergaben sich entsprechende, aber nicht gesicherte Unterschiede. Scheidendichte und Prozentsatz SRP waren gegenläufig, zwei Rübenstämme zeigten eine hohe Scheidendichte, zwei andere hatten weniger Scheiden, aber einen höheren Prozentsatz SRP. Diese Gruppierung der Stämme korrespondierte aber nicht mit ihrer Blattlausresistenz. Aus der Scheidendichte ergab sich, dass M. persicae und A. fabae auf allen geprüften Rübenstämmen, resistenten und anfälligen, unbehindert probten, so dass jede Laus das Phloem durchschnittlich etwa viermal am Tag erreichte. Ein Klon von M. persicae, der sich an Rüben nicht entwickelt, hinterliess weniger Scheiden in den Blättern aller Stämme.Der Anteil von SRP war bei Prüfungen im März grösser als im November. Dieser Unterschied war besonders deutlich bei Scheiden von Larven, die im übrigen zu allen Zeiten das Phloem weniger oft erreichten als ihre Eltern. Messungen des Abstandes von der unteren Blattfläche zum Phloem ergaben, dass das Phloem den Läusen in Gewächshaus-Zuckerrüben immer zugänglich war. M. persicae-Larven konnten jedoch in Blättern von Freilandrüben das Phloem nicht erreichen.