Curie-point pyrolysis mass spectrometry applied to characterization and identification of selected Bacillus species

The use of pyrolysis mass spectrometry in the characterization and identification of Bacillus species was studied. Fifty-three strains of four closely related groups, Bacillus subtilis, B. pumilus, B. licheniformis and 'B. amyloliquefaciens', were used in a study of both sporulated and nonsporulated cultures. Pyrolysis was carried out using a Pyromass 8-80, a novel pyrolysis mass spectrometer specifically designed for fingerprinting complex samples. The pyrolysis data obtained were analysed using multivariate statistical techniques. All four groups could be differentiated using data from non-sporulated cultures but the data from sporulated cultures did not separate B. subtilis from 'B. amyloliquefaciens' or B. pumilus. In contrast, B. licheniformis was more clearly differentiated from the other three species using these data. Culture maturity affected the mass spectra obtained from non-sporulated cultures.     

The influence of ionic strength, pH and a protein layer on the interaction between Streptococcus mutans and glass surfaces

The initial interaction between Streptococcus mutans and hard surfaces has been investigated using a rotating disc technique. The deposition to clean and BSA-coated glass of two strains of S. mutans, FA-1 (serotype b) and KPSK2 (serotype c), which exhibit different surface properties, was studied. Organisms were harvested from cultures grown in a chemostat at a dilution rate of 0.06 h-1 and suspended in NaCl solutions of defined ionic strengths and pH values. The deposition of both strains showed a strong dependence on electrolyte concentration, particularly at low ionic strengths, which was inversely related to the zeta potentials of the organisms. Similarly, the ionic strength at which maximum deposition was first noted (critical coagulation concentration) for the two strains correlated with their relative potentials. Deposition was insensitive to changes in pH at an electrolyte concentration of 0.05 M. The maximum observed deposition did not approach values predicted by theory, suggesting that a further barrier to deposition, other than electrostatic repulsion, might exist. Under all experimental conditions, some of the deposited bacteria were observed to be oscillating, suggesting that they were held at a distance from the collector surface. The cells did not, however, appear to be deposited in a secondary minimum predicted by DLVO theory hence it may be that long-range polymer interactions are also involved in the deposition of these organisms.     

Use of Radiological Facilities by General Practitioners

The 11,360 direct referrals to diagnostic radiological facilities by general practitioners in the Aberdeen area during 1973 were studied. These represented about 12% of the adult radiology performed in the main x-ray departments of the city, and barium meal examinations amounted to half of all such outpatient contrast examinations. Chest x-ray and barium meal examinations were the most frequently used procedures.Some abnormality was detected at 34% of all examinations, and the barium meal examinations requested by general practitioners showed a similar percentage of abnormal findings to those requested by Aberdeen hospital doctors.The average referral rate for all practices was 24·6 per 1,000 practice population per year. Singlehanded general practitioners referred fewer patients for diagnostic radiology than those working in group practices, and rural practitioners referred fewer than urban general practitioners. This trend was emphasized at a distance greater than 15 miles from the city.     

Control of the production of exo-β-N-acetylglucosaminidase by Bacillus subtilis B. Derepression during gluconeogenesis and initial stages of sporulation

1. The control of exo-beta-N-acetylglucosaminidase (EC 3.2.1.30) production by Bacillus subtilis B growing on a chemically defined medium was studied. 2. The enzyme was repressed during exponential growth by those carbon sources that enter the glycolytic pathway above the level of phosphoenolpyruvate. When exponential growth ceased as a result of low concentrations of the nitrogen, carbon or metal ion components of the medium, the enzyme was formed and its amount could be increased by the addition of cell-wall fragments as inducer. 3. The enzyme was de-repressed and could be induced during exponential growth on non-glycolytic compounds metabolized directly into pyruvate, acetyl-CoA or tricarboxylic acid cycle intermediates. 4. The major difference in the metabolism of the organism utilizing these two groups of compound was the existence of high activities of phosphoenolpyruvate carboxylase required for gluconeogenesis. 5. It is concluded that the de-repression of glucosaminidase occurs when the only principal change detected in the intermediary metabolism of the organism was the presence of high activities of phosphoenolpyruvate carboxylase. 6. When the organism was grown on media containing repressing compounds, the enzyme was only de-repressed on entry of the cells into the initial stages of sporulation, where phosphoenolpyruvate carboxylase activity, even in the presence of excess of glucose, increased in parallel with glucosaminidase, neutral proteinase and alkaline phosphatase activities. 7. These results suggest a strong link, at the level of the tricarboxylic acid cycle, between the control of phosphoenolpyruvate carboxylase and the control of the de-repression of glucosaminidase and sporulation.     

A substrate for the fluorogenic assay of exo-beta-N-acetylmuramidase: synthesis and purification of 4-methylumbelliferyl N-acetylmuramide.

A fluorogenic substrate for exo-β-N-acetylmuramidase from Bacillus subtilis B was synthesized. 4-Methyl-2-oxo-1,2-benzopyran-7-yl 2-acetamido-4,6-O-benzylidene-2-deoxy-β-d-glucopyranoside was prepared from 4-methyl-2-oxo-1,2-benzopyran-7-yl 2-acetamido-2-deoxy-β-d-glucopyranoside, condensed with dl-2-chloropropionic acid, the benzylidene residue removed by acetolysis and the 4-methyl-2-oxo-1,2-benzopyran-7-yl 2-amino-3-O-(d-1-carboxyethyl)-2-deoxy-β-d-glucopyranoside purified by chromatography on silica gel and Sephadex G-10 and by high-voltage paper electrophoresis. The identity of the product was confirmed by pmr studies, acid hydrolysis followed by chromatography of the products, and enzymic digestion.     

Multiple paternity in viviparous kelp rockfish, <Emphasis Type="Italic">Sebastes atrovirens</Emphasis>

Analysis of multilocus microsatellite genotypes revealed multiple paternity for all of the seven viable broods of larvae produced by kelp rockfish, Sebastes atrovirens (Jordan and Gilbert 1880), held jointly in a large aquarium tank (n = eight females and eight males). Only two of the eight experimental males were identified as fathers, and alleles not found in any of the captive males were present in all seven broods, demonstrating paternity by wild males external to the experiment. Thus, all of the females mated with one or more males prior to capture, confirming that female kelp rockfish are capable of storing sperm and controlling the overall timing of egg fertilization. These results highlight the potential for a paternal influence on larval quality through female mate choice and sperm competition.     

Defining the fundamental physiological niche of young estuarine fishes and itsrelationship to understanding distribution,vital metrics,and optimal nurseryconditions

Because estuarine nekton are integrators of the environment abiotic and biotic factors can influence or constrain the relative value of estuarine nursery zones. Recent laboratory experiments on young spot, Leiostomus xanthurus, indicate that both water temperature and salinity significantly affect somatic growth. These experimental data contrast with previous work on young Atlantic croaker,Micropogonias undulatus, white trout,Cynoscion arenarius, and mullet,Mugil sp. Together these results suggest that quantifying vital metrics of nekton, such as survival and growth, along realistic environmental gradients through critical laboratory experiments, allows a more accurate definition of constraints on habitat use. Our studies of factors influencing recruitment success in both winter- and spring/summer-spawning fishes illustrate seasonal as well as intrafamilial differences in growth. Effective management of coastal ecosystems must take into account both variability in abiotic conditions and the nested habitat component, both of which can be modified by coastal development, which could lead to reduced productivity and sustainability of these estuarine landscapes.