Exceptional convergent evolution in a virus

Replicate lineages of the bacteriophage phiX 174 adapted to growth at high temperature on either of two hosts exhibited high rates of identical, independent substitutions. Typically, a dozen or more substitutions accumulated in the 5.4-kilobase genome during propagation. Across the entire data set of nine lineages, 119 independent substitutions occurred at 68 nucleotide sites. Over half of these substitutions, accounting for one third of the sites, were identical with substitutions in other lineages. Some convergent substitutions were specific to the host used for phage propagation, but others occurred across both hosts. Continued adaptation of an evolved phage at high temperature, but on the other host, led to additional changes that included reversions of previous substitutions. Phylogenetic reconstruction using the complete genome sequence not only failed to recover the correct evolutionary history because of these convergent changes, but the true history was rejected as being a significantly inferior fit to the data. Replicate lineages subjected to similar environmental challenges showed similar rates of substitution and similar rates of fitness improvement across corresponding times of adaptation. Substitution rates and fitness improvements were higher during the initial period of adaptation than during a later period, except when the host was changed.     

Differential responses in anterior pituitary luteinizing hormone (LH) content and LH beta- and alpha-subunit mRNA, and plasma concentrations of LH and testosterone, in bulls treated with the LH-releasing hormone agonist deslorelin

Tooth loss diminishes oral function and quality of life, and national health targets aim to reduce population levels of tooth loss. OBJECTIVES: The purpose of this study was to determine tooth loss incidence and predictors of tooth loss among older adults in South Australia. METHODS: Data were obtained from a cohort study of a stratified random sample of community-dwelling dentate people aged 60+ years. Interviews and oral examinations were conducted among 911 individuals at baseline and among 693 of them (76.1%) 2 years later. Incidence rates and relative risks were calculated for population subgroups and multivariate logistic regression was used to construct risk prediction models. A method was developed to calculate 95% confidence intervals (95% CI) for relative risks (RR) from logistic regression models using a Taylor series approximation. RESULTS: Some 19.5% (95% CI = 15.4-23.6%) of people lost one or more teeth during the 2 years. Men, people with a recent extraction, people who brushed their teeth infrequently, smokers and people born outside Australia had significantly (P < 0.05) greater risk of tooth loss. Baseline clinical predictors of tooth loss included more missing teeth, retained roots, decayed root surfaces, periodontal pockets and periodontal recession. In a multivariate model that controlled for baseline clinical predictors, former smokers (RR = 2.55, 95% CI = 1.48-4.40) and current smokers (RR = 2.06, 95% CI = 0.92-4.62) had similarly elevated risks of tooth loss compared with non-smokers. CONCLUSIONS: The findings from this population suggest that a history of smoking contributes to tooth loss through mechanisms in addition to clinical disease processes alone.     

Fatty Acids Released from Milk Fat by Lipoprotein Lipase and Lipolytic Psychrotrophs

ABSTRACT: The ability of 13 different strains of psychrotrophs to release free fatty acids in milk was evaluated by using GC analysis. The 13 strains could be categorized into 3 groups: Group 1 consisted of bacteria that grew well and released large quantities of free fatty acids, group 2 consisted of bacteria that grew well but released low amounts of free fatty acids, and group 3 consisted of bacteria that did not grow well nor released large quantities of fatty acids. In group 1, 3 strains were determined to be highly lipolytic, releasing short‐chain fatty acids in amounts greater than reported threshold values. Group 3 consisted of 2 strains, which did not grow well in heat‐treated milk, and the subsequent release of free fatty acids was minor during the 10‐d monitoring time. The other 8 strains tested showed no specific pattern of fatty acid release and quantities of short‐chain fatty acids were not large, despite the ability to grow to high numbers in the treated milk. This work indicates that the lipolytic activity of psychrotrophs common in raw milk is specific to the species and a general prediction of free fatty acid release may not be possible.     

A comparison of the effect of two regimens of infestation on the development of resistance by cattle to the cattle tick, Boophilus microplus (Can.)

The development of resistance to Boophilus microplus by cattle was studied using sets of cattle twins, in stalls. One twin from each set received 3 infestations of 40,000 larvae and the other a continuous infestation of 1,000 larvae a day over the same period. Sets of twins were then challenged with 1,000 larvae a day for 40 days and 2 field infestations of 20,000 larvae. Correlations of ranking for resistance made at 40-day periods during daily infestations of 1,000 larval ticks or for corresponding intermittent infestations of 40,000 larvae were low until animals had received 120,000 larvae. Thereafter irrespective of method of infestation correlations of ranking were relatively high (r = 0.61-0.96) between periods of infestations or method of infestation including 2 field infestations. Fewer adult female ticks matured on the daily infested animals than on the intermittently infested animals during the treatment period, but animals developed a similar resistance level whether infested with either technique.     

A biochemical basis for obligate methylotrophy: properties of a mutant of Pseudomonas AM1 lacking 2-oxoglutarate dehydrogenase

The effects of PGE1 on the dog heart were studied using the blood-perfused sinus node and papillary muscle preparations isolated separately from the same animal. PGE1 administered into the papillary muscle artery as bolus injections in doses of 1-1000 ng caused a dose-dependent increase of the developed tension and dT/dt of the papillary muscle. The effect was not inhibited by the beta-adrenoceptor blocking agent pindolol. PGE1 injected into the sinus node artery in doses of 3-300 ng did not change the rate of contraction of the sinus node preparation. PGE1 in the blood concentrations of 4.4 X 10(-9) to 1.7 X 10(-7) M enhanced the positive inotropic responses to noradrenalin and field stimulation as well as to calcium. The influence of PGE1 on the positive inotropic effect of perivascular nerve stimulation was not consistent: the action of perivascular nerve stimulation was enhanced by PGE1 in the majority of preparations but was reduced in one third of preparations. PGE1 in the same blood concentrations as used in the papillary muscle significantly depressed the positive chronotropic responses to noradrenaline and dopamine. The present results indicate that PGE1 induces multiple actions on the dog heart. Its predominant effect on the ventricular myocardium appears to be enhancement of the adrenergic stimuli probably via the facilitation of calcium movement through the myocardial cell membrane. In addition, PGE1 may decrease the sensitivity of beta-adrenoceptors to adrenergic stimuli in the sinus node.     

An investigation into factors affecting proteocine production by Proteus isolates

Proteocine production was found to the influenced by the medium used, the temperature of incubation and the length of incubation. Different amounts of proteocine were produced in different media. Production in liquid media was maximum in proteose-peptone No. 3 (Difco). This medium gave a very high titre (1:10000) of proteocine when inoculated with the producer strain, and the aerated culture was induced with mitomycin C. Therefore a method of producing a high titre proteocine was developed using proteosepeptone No. 3 (Difco) and cultural conditions of 25 degrees C for 24 hours.     

Human thyroid adenyl cyclase-stimulating activity in immunoglobulin G of patients with Graves' disease

We have studied the characteristics of the stimulation of adenyl cyclase (AC) activity in human thyroid plasma membranes by thyroid-stimulating hormone (TSH) and by immunoglobulin G (IgG) from the sera of patients with Graves' disease. AC activity was measured as adenosine 3',5'-cyclic monophosphate (cAMP) generated by membranes in a 10 minute incubation. IgG from two patients with Graves' disease possessed particularly potent human thyroid AC-stimulating activity; the dose-response curves with these IgGs were essentially parallel to those obtained with TSH. As little as 30 mug of the IgG of one patient with Graves' disease or 8 muU of TSH caused significant AC stimulation. A Lineweaver-Burk plot of the data suggested similarity in the site of action of both TSH and human thyroid adenyl cyclase stimulator (HTACS) in Graves' IgG. Submaximal doses of HTACS and TSH had additive effects on AC stimulation, but a large dose of a Graves' IgG with potent AC stimulating activity did not enhance AC stimulation by a maximal dose of TSH. The effect of HTACS on AC was slower in onset and longer in duration than an equipotent dose of TSH. HTACS was detectable in IgGs of 9 of 15 untreated hyperthyroid Graves' disease patients; its concentration, however, did not correlate significantly with tests of thyroid function, nor with long-acting thyroid stimulator (LATS) activity. In another 11 treated patients with Graves' disease, selected for the presence of LATS, HTACS and LATS were significantly correlated. We observed no inhibition of LATS activity in a Graves' IgG chosen for such testing because of its high titer of HTACS and no detectable LATS. However, an inhibitor of HTACS was detected in 2 of 4 IgGs; one of these two IgGs also inhibited AC stimulation by TSH. Conclusions: 1) Some Graves' disease IgGs contain a human thyroid AC stimulator (HTACS), probably different from LATS. 2) HTACS may act via a common pathway with TSH; it differs from TSH, however, in having a slower onset and a greater effect during more prolonged incubation with plasma membranes. 3) There is also an inhibitor of HTACS activity in some Graves' disease IgGs.     

Effects of testosterone implants in pregnant ewes on their female offspring

Optimal conditions for using high-performance liquid chromatography (HPLC) in the size exclusion mode have been determined for measuring the molecular-weight (MW) distribution of chitosan samples. Physical separation according to molecular size was accomplished on the stationary phase of glass supports having controlled pore sizes ranging from 2500 to 40 A. Selection of column combinations was based on the requirements to resolve the higher MW fraction of chitosan and to give a linear calibration curve within the required MW range. The best combination of glass pore sizes and column lengths in two foot sections joined sequentially was: 2500 A (2 ft.), 1500 A (4 ft.), 550 A (6 ft.), 250 A (2 ft), 100 A (2 ft.), and 40 A (2 ft.). A loading study showed that an injection load of 500 mug, i.e. 100 mul at 5 g/l or 50 mul at 10 g/l (w/v), was the optimal load to give reproducible elution volumes, precision in quantitation, and minimum viscosity effects. The best calibration curve using defined dextran standards was obtained from the geometric mean of Mw (weight average MW) and Mn (number average MW) values and peak elution volumes. Precision in determining MW distribution of chitosan as well as dextran standards was better than 5% relative standard deviation, and the differences between these results and the manufacturer's data on the dextran standards were 6 to -17%. The MW distribution of a selected chitosan samples in 2% acetic acid thus determined was Mw = 2,055,000, Mn = 936,000, dispersity = 2.16, and the most abundant species was around 1,103,000. Analysis time for the HPLC separation was less than 20 min per sample. Chitosan is an effective coagulating agent for the treatment of food processing wastes and activated sludge from biological treatment systems. It is manufactured from chitin in shrimp and crab wastes. The rapid methods developed here for determining the MW distribution of chitosan preparations will be used to optimize the manufacturing process and guide the selection of more effective chitosan products.     

Operative correction of pectus excavatum: an evolving perspective

Volatile free fatty acids (VFA) in blood increased approximately twofold in dogs subjected to total hepatectomy. The average total plasma VFA preoperatively was 1,585 mug percent and shortly before death, postoperatively, was 2,798 mug percent. The corresponding red cell concentrations were essentially the same. Acetic acid was 81 percent of the total VFA, propionic acid 7 percent, isobutyric acid 4 percent, butyric acid one percent, and isovaleric acid 5 percent. There was little or no isovalerate in red cells. The increments in the individual fatty acids after hepatectomy were highly variable, but the average increase with time was almost linear. The increase in VFA probably reflects an increased utilization of the branched-chain aminoacids by extrahepatic tissues.     

NO- and NO2-carrying molecules potentiate photorelaxation in rat trachea and aorta

Photorelaxation elicited by ultraviolet light (366 nm) was investigated on isolated rat thoracic aorta and trachealis. Rat tracheal smooth muscle but not aorta did not show UV-induced photorelaxation. Both streptozotocin, NO-carrying molecule and N omega-nitro-L-arginine, NO2-carrying molecule significantly enhanced photorelaxation, concentration-dependently, in rat trachealis and aorta. Methylene blue (10 microM) inhibited the potentiation action of streptozotocin and N omega-nitro-L-arginine in both tissues. Superoxide dismutase (300 U/ml) enhanced streptozotocin- and N omega-nitro-L-arginine-potentiated photorelaxation in rat trachealis, while pyrogallol (0.1 mM), a potent O2- generating agent, inhibited streptozotocin-potentiated photorelaxation in trachealis. Streptozotocin was much more effective than N omega-nitro-L-Arginine in potentiating of photorelaxation elicited by UV light in both tissues. From these findings, we conclude that streptozotocin and N omega-nitro-L-arginine produce EDRF like labile substance(s) by UV irradiation.