Chromosome aberrations in pressure-induced triploid Atlantic salmon.

BACKGROUND: Triploid organisms have three sets of chromosomes. In Atlantic salmon, hydrostatic pressure treatment of newly fertilized eggs has been extensively used to produce triploids which are functionally sterile due to their unpaired chromosomes. These fish often perform poorly on commercial farms, sometimes without explanation. Inheritance patterns in individuals subjected to pressure treatment have not been investigated in Atlantic salmon thus far. However, work on other species suggests that this treatment can result in aberrant inheritance. We therefore studied this in Atlantic salmon by genotyping 16 polymorphic microsatellites in eyed eggs and juveniles which had been subjected to pressure-induction of triploidy. Communally reared juveniles including fish subjected to pressure-induction of triploidy and their diploid siblings were included as a control. RESULTS: No diploid offspring were detected in any of the eggs or juveniles which were subjected to hydrostatic pressure; therefore, the induction of triploidy was highly successful. Aberrant inheritance was nevertheless observed in 0.9% of the eggs and 0.9% of the juveniles that had been subjected to pressure treatment. In the communally reared fish, 0.3% of the fish subjected to pressure treatment displayed aberrant inheritance, while their diploid controls displayed 0% aberrant inheritance. Inheritance errors included two eyed eggs lacking maternal DNA across all microsatellites, and, examples in both eggs and juveniles of either the maternal or paternal allele lacking in one of the microsatellites. All individuals displaying chromosome aberrations were otherwise triploid. CONCLUSIONS: This is the first study to document aberrant inheritance in Atlantic salmon that have been subjected to pressure-induction of triploidy. Our experiments unequivocally demonstrate that even when induction of triploidy is highly successful, this treatment can cause chromosome aberrations in this species. Based upon our novel data, and earlier studies in other organisms, we hypothesize that in batches of Atlantic salmon where low to modest triploid induction rates have been reported, aberrant inheritance is likely to be higher than the rates observed here. Therefore, we tentatively suggest that this could contribute to the unexplained poor performance of triploid salmon that is occasionally reported in commercial aquaculture. These hypotheses require further investigation.

Implications for introgression: has selection for fast growth altered the size threshold for precocious male maturation in domesticated Atlantic salmon?

BACKGROUND: Mature male parr (MMP) represent an important alternative life-history strategy in Atlantic salmon populations. Previous studies indicate that the maturation size threshold for male parr varies among wild populations and is influenced by individual growth, environmental conditions, and genetics. More than ten generations of breeding have resulted in domesticated salmon displaying many genetic differences to wild salmon, including greatly increased growth rates. This may have resulted in domesticated fish with the potential to outgrow the size threshold for early maturation, or evolution of the size threshold of the trait itself. To investigate this, we performed a common-garden experiment under farming conditions using 4680 salmon from 39 families representing four wild, two wild-domesticated hybrid, and two domesticated strains. RESULTS: Domesticated salmon outgrew wild salmon 2-5-fold, and hybrids displayed intermediate growth. Overall, the numbers of MMP varied greatly among families and strains: averaging 4-12% in domesticated, 18-25% in hybrid, and 43-74% in the wild populations. However, when the influence of growth was accounted for, by dividing fish into lower and upper size modes, no difference in the incidence of MMP was detected among domesticated and wild strains in either size mode. In the lower size mode, hybrids displayed significantly lower incidences of mature males than their wild parental strains. No consistent differences in the body size of MMP, connected to domestication, was detected. CONCLUSIONS: Our data demonstrate: 1- no evidence for the evolution of the size threshold for MMP in domesticated salmon, 2- the vastly lower incidence of MMP in domesticated strains under aquaculture conditions is primarily due to their genetically increased growth rate causing them to outgrow the size threshold for early maturation, 3- the incidence of MMP is likely to overlap among domesticated and wild salmon in the natural habitat where they typically display overlapping growth, although hybrid offspring may display lower incidences of mature male parr. These results have implications for wild salmon populations that are exposed to introgression from domesticated escapees.

Ploidy elicits a whole-genome dosage effect: growth of triploid Atlantic salmon is linked to the genetic origin of the second maternal chromosome set.

BACKGROUND: The Atlantic salmon aquaculture industry is investigating the feasibility of using sterile triploids to mitigate genetic interactions with wild conspecifics, however, studies investigating diploid and triploid performance often show contrasting results. Studies have identified dosage and dosage-compensation effects for gene expression between triploid and diploid salmonids, but no study has investigated how ploidy and parent-origin effects interact on a polygenic trait in divergent lines of Atlantic salmon (i.e. slow growing wild versus fast growing domesticated phenotype). This study utilised two experiments relating to the freshwater growth of diploid and triploid groups of pure wild (0% domesticated genome), pure domesticated (100% domesticated genome), and F1 reciprocal hybrid (33%, 50% or 66% domesticated genome) salmon where triploidy was either artificially induced (experiment 1) or naturally developed/spontaneous (experiment 2). RESULTS: In both experiments, reciprocal hybrid growth was influenced by the dosage effect of the second maternal chromosome, with growth increasing as ploidy level increased in individuals with a domesticated dam (from 50% to 66% domesticated genome), and the inverse in individuals with a wild dam (from 50% to 33% domesticated genome). CONCLUSIONS: We demonstrate that the combined effect of ploidy and parent-origin on growth, a polygenic trait, is regulated in an additive pattern. Therefore, in order to maximise growth potential, the aquaculture industry should consider placing more emphasis on the breeding value of the dam than the sire when producing triploid families for commercial production.

Plasticity in response to feed availability: Does feeding regime influence the relative growth performance of domesticated, wild and hybrid Atlantic salmon Salmo salar parr?

Growth of farmed, wild and F1 hybrid Atlantic salmon parr Salmo salar was investigated under three contrasting feeding regimes in order to understand how varying levels of food availability affects relative growth. Treatments consisted of standard hatchery feeding (ad libitum), access to feed for 4 h every day, and access to feed for 24 h on three alternate days weekly. Mortality was low in all treatments, and food availability had no effect on survival of all groups. The offspring of farmed S. salar significantly outgrew the wild S. salar, while hybrids displayed intermediate growth. Furthermore, the relative growth differences between the farmed and wild S. salar did not change across feeding treatments, indicating a similar plasticity in response to feed availability. Although undertaken in a hatchery setting, these results suggest that food availability may not be the sole driver behind the observed reduced growth differences found between farmed and wild fishes under natural conditions.

Water diffusivity in starch-based systems.

The objective of this study was to investigate the influence of structure, and component interactions, on the sorption and transport properties of water in starch-based systems. We compared the effective diffusivity (Deff) of water in two starches, with differing amylose-amylopectin ratios, using either kinetics of water adsorption or analysis of drying curves (water desorption) to estimate Deff. The effect of incorporating small sugar molecules into the granular or gelatinized starch matrices on Deff was measured by drying curve analysis. To investigate the possible mechanisms of water transport, the porosity and microscopic appearance of the samples at different stages of drying were determined. In a complementary study, sorption isotherms and the number of accessible "binding" sites in the starch and starch-sugar systems were determined using gravimetric analysis and inverse gas chromatography (IGC) 'probe analysis'. In the case of the starch-sugar systems, the measurements were made after the components had been 'mechanically mixed', or after more intimate mixing had been achieved by a co-freeze-drying process. The Deff of the starches was found to depend, in a complex way, on the moisture content of the samples. At relatively high moisture contents, the predominant mode of water transport was by liquid diffusion. As the samples became drier, their porosity increased, and the predominant mode of moisture transport was by vapor phase diffusion. As the samples became very dry (less than 10% water content), Deff fell significantly. Incorporation of sugars, in general, led to a reduction of Deff, which was correlated with a corresponding fall in porosity. In agreement with the findings of other workers, for the starches studied, the value of Deff determined from water adsorption measurements was significantly less than Deff determined from water desorption (drying curve analysis). The form of the Deff versus moisture content relationship was, however, independent of the method of measurement (adsorption or desorption). The water sorption and IGC probe analysis results indicated that some physicochemical interaction was expedited by the freeze-drying process. This interaction was manifested by a reduction in water sorption at a given relative vapor pressure, and by major changes in the accessibility of the co-freeze-dried samples to organic probe molecules. Taken together, the results indicate that water transport (diffusion) in starches and in starch-sugar mixtures is dependent significantly on gross structural features (development of porosity during drying), but that specific molecular, physico-chemical interactions must also be considered.

Level of compliance with the radiation protection regulation--a survey among Norwegian hospitals and X-ray institutes.

To identify the level of compliance with the new radiation protection regulation among Norwegian health care enterprises (HCEs). Totally, 41 HCEs were authorised to use advanced X-ray equipment for medical purposes during 2005-07. Follow-up inspections with 14 HCEs were carried out during 2007-09. Main topics for the inspections were those requirements identified as most challenging to implement in the authorisation process. Totally, 192 non-conformities with the regulation were revealed during the authorisation process. The inspections revealed that 93 % of the inspected HCEs had non-conformities with the regulation. Most common non-conformities dealt with skills in radiation protection, establishment of local diagnostic reference levels, access to medical physicists and performance of quality control of X-ray equipment. Inspections are an effective tool for implementation of regulation the requirements at the HCEs, thus improving radiation protection awareness.

An intensified lifestyle intervention programme may be superior to insulin treatment in poorly controlled Type 2 diabetic patients on oral hypoglycaemic agents: results of a feasibility study.

AIMS: The aims of this study were to assess whether, in Type 2 diabetic patients with inadequate glycaemic control on oral hypoglycaemic agents (OHA), a lifestyle intervention programme based on exercise and diet counselling (i) was as effective as insulin treatment in controlling blood glucose, and (ii) could prevent the weight gain usually accompanying the introduction of insulin treatment. METHODS: Thirty-eight Type 2 diabetic subjects treated with OHA, HbA(1c) 8-10.5% and body mass index (BMI) 26-40 kg/m2, were randomized to the following treatments: (i) lifestyle intervention (L), (ii) lifestyle intervention + insulin treatment (L+I) and (iii) insulin treatment alone (I). RESULTS: There was a reduction in HbA(1c) of -1.2 (interquartile range 1.0), -1.0 (1.7) and -1.5 (2.5)% in group L, L+I and I, respectively, and all treatment groups achieved beneficial changes in blood lipid variables. There was no significant difference between the groups in the change observed in levels of HbA(1c) between start and 12 months of treatment (P = 0.74). There was a significant difference in weight changes between groups (P < 0.01): group L reduced weight by median -3.0 (4.0) kg, groups L+I and I increased weight by 3.5 (3.4) and 4.9 (6.9) kg, respectively. CONCLUSIONS: Lifestyle intervention was as effective as insulin treatment in improving glycaemic control in poorly controlled subjects with Type 2 diabetes, and resulted in weight loss during the intervention year. However, glycaemic control deteriorated and body weight increased in the lifestyle intervention group 1 year after the intervention stopped.

Asexual developmental markers in an aflatoxigenic strain of Aspergillus parasiticus.

The relationships between specific asexual development stages of Aspergillus parasiticus and potential enzyme markers of these stages were established. Competence was reached when culture age was 22.6 h for an initial inoculum level of 3.0 X 10(2) conidia X mL-1 and 8.09 h for an initial inoculum level of 2.0 X 10(4) conidia X mL-1. The appearance of laccase activity was correlated with the development of conidia. Laccase activity was detected only in conidiating cultures. Activity was inhibited in shaking cultures due to inhibition of conidiation. Laccase activity reached a maximum in cultures after 120 h. Inducible nitrate reductase activity was detected in A. parasiticus cultures after competence was established.

Inhibition of Clostridium perfringens by heated combinations of nitrite, sulfur, and ferrous or ferric ions.

Heating mixtures of sodium nitrite, cysteine, and either ferrous sulfate or ferric chloride at 121 C for 20 min at pH 6.5 or 6.3 produced a potent inhibitor of Clostridium perfringens vegetative cells and spores when added to previously heat-sterilized fluid thioglycolate medium. When the mixtures containing FeSO4 at pH 5.2 or FeCl3 at pH 2.7 were heated, the inhibitory effect was not produced. These responses seem to eliminate the possibility that cysteine nitrosothiol is the agent responsible for the heated-nitrite inhibition known as the Perigo effect. The variable pH responses also cast doubt upon the role of the black Roussin salt as the agent of the Perigo effect.

Isolation of a plasmid responsible for caseinase activity in Clostridium perfringens ATCC 3626B.

Clostridium perfringens strain ATCC 3626B was cured of caseinase activity at a high frequency after treatment with acriflavine dye (2.5%) or elevated temperature growth (9.1%). Caseinase-negative isolates retained the larger (9.4 megadaltons) pHB102 cryptic plasmid, but were missing the smaller (2.1 megadaltons) pHB101 plasmid present in the caseinase-positive wild-type strain. Dye-buoyant density-gradient centrifugation at 4 or 15 degrees C revealed that the pHB101 and pHB102 plasmids are temperature labile and easily converted into the nicked non-supercoiled or linear state.

Redox potential-dependent nitrite metabolism by Salmonella typhimurium.

Salmonellae are generally resistant to the inhibitory effects of NaNO2. Removal of the lipopolysaccharide of Salmonella typhimurium by ethylenediaminetetraacetic acid pretreatment did not result in subsequent inhibtion of growth by NaNO2, indicating that lipopolysaccharide does not function to exclude NaNO2 from the cell. NaNO2 disappeared from the medium while the cells were growing, but, after stationary phase was reached, no further losses were observed unless the pH was maintained above 7.0. Similar losses were observed in a cell-free system if the redox potential of the medium was between -250 and -175 mV. If the disrupted cell suspension was first heated in a boiling water bath for 15 to 18 min, no NaNO2 loss was observed regardless of the redox potential. S. typhimurium is capable of metabolizing NaNO2, possibly by means of a nitrite-reducing enzyme function which is redox controlled.

A technique for producing large yields of vegetative cell-free refractile Clostridium perfringens spores of unaltered heat resistance.

Sonic treatment of sporulated Clostridium perfringens cultures produced suspensions free of vegetative cells without altering viable spore counts or thermal resistance.

Evaluation of a fluorescent antibody-enrichment serology combination procedure for the detection of salmonellae in condiments, food products, food by-products, and animal feeds.

The reliability of the enrichment serology (ES), fluorescent antibody (FA), and a combination of the FA and ES procedures for the detection of salmonellae were compared to the Salmonella cultural procedure outlined in the U.S. Food and Drug Administration's Bacteriological Analytical Manual (BAM). A total of 126 subsamples from 22 different products were analyzed. By utilizing the BAM procedure as the reference standard, a total of 66 samples were positive for salmonellae. Within 44 h approximately 65% of the Salmonella-negative samples could be cleared by the FA test. At the end of 50 h 97% of the Salmonella-negative samples could be cleared by the combination FA-ES test. The FA procedure detected all 66 BAM positives but exhibited a high incidence of presumptive positives which were cultural negatives. The ES procedure detected 64 of the 66 BAM positives but exhibited a low incidence of presumptive positives which were cultural negatives. Incorporating positive FA and positive ES results in a combination FA-ES technique revealed that FA-ES positives were statistically equivalent to BAM positives.

Chemically defined medium for the growth of Clostridium perfringens.

A defined medium which supports growth of Clostridium perfringens at low inoculum levels was developed. Generation time for strain 8797 was 1.5 times greater than previously reported for growth in purged fluid thioglycolate medium.

Effect of sodium nitrite inhibition on intracellular thiol groups and on the activity of certain glycolytic enzymes in Clostridium perfringens.

Activities of glyceraldehyde-3-phosphate dehydrogenase (EC 1.2.1.12) (GAP-DH) and aldolase (EC 4.1.2.13) in cells of Clostridium perfringens that had been inhibited with sodium nitrite were investigated. A complete loss in GAP-DH activity and a 67% decrease in aldolase activity were observed when growth of C. perfringens was inhibited. There was also a 91% decrease in the concentration of free sulfhydryl groups of soluble cellular components. Dithiothreitol restored some activity to inactive GAP-DH from sodium nitrite-inhibited cells, indicating that a loss of reduced sulfhydryl groups was involved in the inactivation of the enzyme. The evidence presented suggests that sodium nitrite inhibition of C. perfringens may involve an interaction of sodium nitrite as nitrous acid with sulfhydryl-containing constituents of the bacterial cell.

New medium for the isolation and enumeration of pseudomonads.

A new medium containing 200 ppb of 2-hydroxy-2',4,4'-trichlorodiphenyloxide (CH3565) and 10 ppm of cetyl-trimethyl-ammonium bromide (Cetrimide) in tryptic soy agar was developed and tested with 19 pure cultures of Pseudomonas, 20 microorganisms of other genera, commercially prepared ground beef, and laboratory-prepared inoculated ground beef. The new medium, CETCH agar, was compared with an antibiotic-containing medium. CETCH agar provided greater pseudomonad recoveries, a shorter incubation period prior to plate counting, and greater ease of preparation.

Development of a minimal medium for Clostridium perfringens by using an anaerobic chemostat.

A minimal medium was developed for the cultivation of Clostridium perfringens in an anaerobic chemostat. Cultures of C. perfringens ATCC 3624 and NCTC 10240 were grown at 46 and 43 degrees C, respectively, in a glucose-limited, chemically defined medium at pH 7.2. The concentrations of amino acids, minerals, nucleotides, and vitamins, initially present in excess, were varied independently. The minimum concentration of each nutrient which would support 3 X 10(8) CFU/ml with a generation time of less than 40 min was determined and used to develop a reformulated defined medium. Atomic absorption spectroscopy and amino acid analyses of the reformulated medium indicated additional adjustments in nutrient content which led to the development of a minimal medium for each strain. The nutritional profile for each strain was similar. A decrease in the concentration of arginine, histidine, and tyrosine for strain 3624 and of arginine, histidine, and isoleucine for strain 10240 resulted in an increase in the optical density of each culture.

Bovine serum eliminates rapid nonspecific toxic reactions during bioassay of stored fish for Clostridium botulinum toxin.

When stored fish or some fish products were tested for the presence of Clostridium botulinum toxin, nonspecific toxic reactions in mice often occurred, rendering the bioassay inconclusive. The nonspecific toxic reactions were mediated by the gram-negative microbiota, inherent to the fish, which were the source of lethal, heat-stable endotoxins. The treatment of assay samples with bovine serum eliminated nonspecific reactions through the interaction of constituent serum immunoglobulin M (IgM) with endotoxic material. Removal of IgM from bovine serum through treatment with protein A or concanavalin A resulted in a loss of protective activity.

Complications and short-term consequences of tubal sterilization. A personal three- and twelve-month follow-up investigation.

The aim of the present study was to investigate the short-term complications and consequences of 216 consecutive female sterilizations. Information was obtained from 211 women (98%) within the first postoperative year. There was one failure (Pomeroy), three skin burns, a vesical lesion and problems with the induction of anesthesia in 2 cases. Thirty-nine women were bothered by minor complaints for 3 months or more, in most cases by discomfort of the laparotomy scar. The impact on postoperative marital life was mainly positive. Twenty-three women expressed doubts whether the sterilization had been sensible, 10 expressed real regret at at least one interview. At one year, 4 stated serious regret. One year after surgery, 68% had told friends about the sterilization; these women were younger than the remainder. Forty-six percent said they would have preferred an earlier operation.

A controlled comparison of the Pomeroy resection technique and laparoscopic electrocoagulation of the tubes.

The Pomeroy resection technique and laparoscopic electrocoagulation of the tubes are compared in a controlled study. Information was obtained during the patients' stay in hospital and at three and 12 months after operation. There were no significant differences between the study groups concerning age, social group, parity, contraceptive practices or age of the children. The surgery time, stay in hospital, periods of postoperative discomfort and sick leave were shorter in the laparoscopy group, and there were fewer postoperative complaints than in the laparotomy group. No differences in the impact on postoperative bleeding patterns were demonstrated.