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PubMed2006

Prevalence and survival of Listeria monocytogenes in Danish aquatic and fish-processing environments.

Listeria monocytogenes contamination of ready-to-eat food products such as cold-smoked fish is often caused by pathogen subtypes persisting in food-processing environments. The purpose of the present study was to determine whether these L. monocytogenes subtypes can be found in the outside environment, i.e., outside food processing plants, and whether they survive better in the aquatic environment than do other strains. A total of 400 samples were collected from the outside environment, fish slaughterhouses, fish farms, and a smokehouse. L. monocytogenes was not detected in a freshwater stream, but prevalence increased with the degree of human activity: 2% in seawater fish farms, 10% in freshwater fish farms, 16% in fish slaughterhouses, and 68% in a fish smokehouse. The fish farms and slaughterhouses processed Danish rainbow trout, whereas the smokehouse was used for farm-raised Norwegian salmon. No variation with season was observed. Inside the processing plants, the pattern of randomly amplified polymorphic DNA (RAPD) types was homogeneous, but greater diversity existed among isolates from the outside environments. The RAPD type dominating the inside of the fish smokehouse was found only sporadically in outside environments. To examine survival in different environments, L. monocytogenes or Listeria innocua strains were inoculated into freshwater and saltwater microcosms. Pathogen counts decreased over time in Instant Ocean and remained constant in phosphate-buffered saline. In contrast, counts decreased rapidly in natural seawater and fresh water. The count reduction was much slower when the natural waters were autoclaved or filtered (0.2-microm pore size), indicating that the pathogen reduction in natural waters was attributable to a biological mechanism, e.g., protozoan grazing. A low prevalence of L. monocytogenes was found in the outside environment, and the bacteria did not survive well in natural environments. Therefore, L. monocytogenes in the outer environment associated with Danish fish processing is probably of minor importance to the environment inside a fish production plant.

Animals↗

PubMed2001

The effect of maternal and paternal environments on seed characters in the herbaceous plant Campanula Americana (Campanulaceae).

Maternal environments typically influence the phenotype of their offspring. However, the effect of the paternal environment or the potential for joint effects of both parental environments on offspring characters is poorly understood. Two populations of Campanula americana, a woodland herb with a variable life history, were used to determine the influence of maternal and paternal light and nutrient environments on offspring seed characters. Families were grown in the greenhouse in three levels of light or three levels of nutrients. Crosses were conducted within each environmental gradient to produce seeds with all combinations of maternal and paternal environments. On average, increasing maternal nutrient and light levels increased seed mass and decreased percentage germination. The paternal environment affected seed mass, germination time, and percentage germination. However, the influence of the paternal environment varied across maternal environments, suggesting that paternal environmental effects should be evaluated in the context of maternal environments. Significant interactions between family and the parental environments for offspring characters suggest that parental environmental effects are genetically variable. In C. americana, the timing of germination determines life history. Therefore parental environmental effects on germination timing, and genetic variation in those parental effects, suggest that parental environments may influence life history evolution in this system.

Journal Article↗

PubMed1991

Effect of first-grade classroom environment on shy behavior, aggressive behavior, and concentration problems.

Investigates the effect of the first-grade classroom environment on the shy behavior, aggressive behavior, and concentration problems of 609 children in 19 East Baltimore public schools. First-grade classroom environment was assessed in terms of dominant pattern of classroom achievement and behavior. Structured teacher ratings assessed child shy behavior, aggressive behavior, and concentration problems at the end of first grade. Children in low-achieving classroom environments had significantly higher teacher ratings of shy behavior and aggressive behavior than children in mixed-achieving or high-achieving environments, even after controlling for potentially confounding child characteristics and classroom behavior environment effects. Analyses controlling for child characteristics and classroom achievement environment effects indicated that children in poor-behaving classroom environments also had significantly higher teacher ratings of shy behavior than children who were not in poor-behaving environments. Subgroup analyses indicated that repeaters in mixed-achieving environments had significantly higher levels of shy behavior compared with nonrepeaters, and repeaters in poor-behaving environments had significantly higher levels of aggressive behavior compared with nonrepeaters. Implications for prevention research are discussed.

Achievement↗

PubMed2005

Virtually driving: are the driving environments "real enough" for exposure therapy with accident victims? An explorative study.

There is a small but growing body of research supporting the effectiveness of computer-generated environments in exposure therapy for driving phobia. However, research also suggests that difficulties can readily arise whereby patients do not immerse in simulated driving scenes. The simulated driving environments are not "real enough" to undertake exposure therapy. This sets a limitation to the use of virtual reality (VR) exposure therapy as a treatment modality for driving phobia. The aim of this study was to investigate if a clinically acceptable immersion/presence rate of >80% could be achieved for driving phobia subjects in computer generated environments by modifying external factors in the driving environment. Eleven patients referred from the Accident and Emergency Department of a general hospital or from their General Practitioner following a motor vehicle accident, who met DSM-IV criteria for Specific Phobia-driving were exposed to a computer-generated driving environment using computer driving games (London Racer/Midtown Madness). In an attempt to make the driving environments "real enough," external factors were modified by (a) projection of images onto a large screen, (b) viewing the scene through a windscreen, (c) using car seats for both driver and passenger, and (d) increasing vibration sense through use of more powerful subwoofers. Patients undertook a trial session involving driving through computer environments with graded risk of an accident. "Immersion/presence" was operationally defined as a subjective rating by the subject that the environment "feels real," together with an increase in subjective units of distress (SUD) ratings of >3 and/or an increase of heart rate of >15 beats per minute (BPM). Ten of 11 (91%) of the driving phobic subjects met the criteria for immersion/presence in the driving environment enabling progression to VR exposure therapy. These provisional findings suggest that the paradigm adopted in this study might be an effective and relatively inexpensive means of developing driving environments "real enough," to make VR exposure therapy a viable treatment modality for driving phobia following a motor vehicle accident (MVA).

Accidents, Traffic↗

PubMed1998

The effects of an enhanced environment on nursing home residents who pace.

This study sought to enhance the well-being of older nursing home residents who pace and wander by enriching their nursing home environment. Visual, auditory, and olfactory stimuli were added to the nursing home unit environment to simulate two types of environments: a home environment and an outdoor nature environment. Participants seemed to prefer the enhanced environments by choosing to spend more time in them, and by sitting on benches in those environments. There was a trend toward less trespassing, exit-seeking, and other agitated behaviors being exhibited in the enhanced environment, and residents were observed to manifest more pleasure in it. Staff members and family members definitely expressed a preference for the enhanced environment over the regular one. Although effects on residents were limited, this approach offers a low-cost method for making the nursing home environment a better place for those residents.

Aged↗

PubMed2006

Caring or uncaring--meanings of being in an oncology environment.

AIM: This paper reports a study illuminating meanings of being in the physical environment of an oncology centre as narrated by patients, significant others and staff. BACKGROUND: The physical environment of hospitals can convey different messages. For example, landscape pictures, plants and comfortable chairs can convey positive messages, while sparsely decorated and run-down environments can convey negative values. Traditional healthcare environments may be experienced as unfamiliar, strange and alienating, fostering feelings of stress and vulnerability. The majority of research on care environments has employed experimental designs to test different environmental variables, for example sound, colour and architecture, in relation to patient outcomes such as recovery, pain and blood pressure. There is, however, little research-based understanding of the meanings of being in these environments. METHODS: A phenomenological hermeneutic approach was applied to analyse 17 interviews with patients, significant others and staff carried out during the spring of 2004 at an oncology centre in Sweden. FINDINGS: The physical environment was found to influence experiences of care in four ways: first, by being a symbol expressing messages of death and dying, danger, shame and stigma, less social value and worth; second by containing symbols expressing messages of caring and uncaring, life and death; third, by influencing interaction and the balance between being involved and finding privacy; and fourth, by containing objects that could facilitate a shift of focus away from the self: being able to escape the world of cancer, and finding light in the midst of darkness. The comprehensive understanding illuminates the physical environment as not merely a place for caring, but as an important part of caring that needs to be accounted for in nursing care. CONCLUSION: To promote well-being among patients, we need to ask ourselves if the environment imposes rather than eases suffering. Our findings also suggest the importance of not limiting our conceptions of nursing to nurse-patient relationships, but of using the therapeutic potential of the total environment in nursing care.

Adult↗

PubMed2004

Effect of environment on resistance to the European corn borer (Lepidoptera: Crambidae) in maize.

The European corn borer, Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae), is a major pest of maize, Zea mays L., in many temperate parts of the world. Genotype-by-environment interaction effects can make relative performance unpredictable and may hamper selection for resistance to European corn borer. The objective of this study was to determine the effect of environment on genotypic reaction to European corn borer resistance in maize. A set of 12 maize inbred lines was chosen to represent a range of European corn borer responses. Eleven testing environments ranged from Delaware, Ohio, Illinois, Iowa, Nebraska, Missouri, to Mississippi. For length of stalk tunneling, environmental and genotypic main effects (estimated by restricted maximum likelihood) were >20- and 10-fold larger than their interaction effect, respectively. Length of tunneling means for genotypes (across environments) ranged from 10.1 to 35.4 cm. Several putatively resistant genotypes grouped with the susceptible checks, B73 and Mol7. By breaking factors and the interaction into single degree of freedom components, we observed that GEMS-0001 had significant crossover interactions toward less susceptibility in both Mississippi and the Nebraska environments. Environments displaying several crossover interactions indicated that European corn borer screening at these sites would not necessarily apply to other locations, whether due to small differences in experimental conduct and/or environmental effects. The five most resistant genotypes were fairly consistent across environments. Because all environments except Illinois used larvae from the same insectary, and these environments differed in damage intensity and rankings, it is unlikely that insect biotype was a factor contributing to genotype-by-environment effects.

Animals↗

PubMed2004

Genotype x environment interactions and genetic parameters for fecal egg count and production traits of Merino sheep.

Breeding for host resistance to parasites has become an imperative in many sheep industries. Because of the widespread use of AI in sheep breeding schemes, it is important to understand how the performance of offspring from rams varies in different flock environments, both for resistance to parasites and key production traits. This study used both variance component and reaction norm models to investigate the level of genotype x environment interaction for fecal egg count (FEC) and important Merino production traits in a range of flock environments in Australia. These flocks were linked by the use of common rams in a sire-referencing scheme. Both linear and quadratic polynomial reaction norm models were used. The heritability of these traits and the genetic correlation between them and FEC also was investigated using the reaction norm model. A contemporary group (CG) was defined by a flock, year, age class, sex, and paddock combination. Each CG environment was characterized by the mean value of any given trait for that CG. The recorded data used in the study were analyzed in a standardized form. Standardization for each trait was achieved within a CG by subtracting the CG mean from each observation and dividing by the CG SD. The genotype x environment effect accounted for <0.05 of the phenotypic variance for all traits. In most traits the heritability varied little across environments. The exceptions were FEC, BW, and both greasy and clean fleece weights, which had a higher heritability at the lower end of the environmental range. Fecal egg count also had a higher heritability in high-FEC environments. Genetic correlations between FEC and several key production traits were similar in the flock environments studied. Quadratic polynomial models and models with a variable residual fitted the data better than linear models. The genotype x environment effect for FEC and the genetic correlations between FEC and production traits were effectively zero; thus, sheep breeding programs for increased parasite resistance can be run effectively by ignoring these factors. Some account should be taken of the high heritabilities of FEC and fleece and BW in different flock environments.

Animals↗

PubMed1990

Person-environment fit as a predictor of hospital pharmacist job performance.

The relationship between person-environment fit and job performance of hospital pharmacists was examined. Person-environment fit is the extent to which personal needs are supplied in the work environment. Pharmacists (n = 86) from 10 hospitals completed a survey that assessed their need for certain attributes in the work environment and their perception of the extent to which those attributes were supplied. Statements from the Jackson Personality Research Form A were used to assess need for achievement, autonomy, cognitive structure, endurance, order, and social recognition. Statements from the same form were used to assess the degree to which respondents perceived that the hospital pharmacy environment supplied the six attributes. Person-environment fit was calculated by subtracting the environmental supply score from the personal need score. Job performance was rated by supervisors. The respondents' highest need was for achievement and lowest need was for autonomy. The supply of five of the attributes was rated similarly; the supply of autonomy was perceived to be significantly lower. Scores for person-environment fit showed that the need for endurance was most closely matched by the work environment and the need for autonomy was most poorly matched. Overall job performance was not predicted by the person-environment fit score for any of the attributes. The supply of autonomy predicted 17% of the variance in performance scores. Job performance was significantly associated with the environmental supply of autonomy but not with person-environment fit.

Employee Performance Appraisal↗

PubMed2006

A systematic investigation of the rate laws valid in intracellular environments.

Recently there has been significant interest in deducing the form of the rate laws for chemical reactions occurring in the intracellular environment. This environment is typically characterized by low-dimensionality and a high macromolecular content; this leads to a spatial heterogeneity not typical of the well stirred in vitro environments. For this reason, the classical law of mass action has been presumed to be invalid for modeling intracellular reactions. Using lattice-gas automata models, it has recently been postulated [H. Berry, Monte Carlo simulations of enzyme reactions in two dimensions: Fractal kinetics and spatial segregation, Biophys. J. 83 (2002) 1891-1901; S. Schnell, T.E. Turner, Reaction kinetics in intracellular environments with macromolecular crowding: simulations and rate laws, Prog. Biophys. Mol. Biol. 85 (2004) 235-260] that the reaction kinetics is fractal-like. In this article we systematically investigate for the first time how the rate laws describing intracellular reactions vary as a function of: the geometry and size of the intracellular surface on which the reactions occur, the mobility of the macromolecules responsible for the crowding effects, the initial reactant concentrations and the probability of reaction between two reactant molecules. We also compare the rate laws valid in heterogeneous environments in which there is an underlying spatial lattice, for example crystalline alloys, with the rate laws valid in heterogeneous environments where there is no such natural lattice, for example in intracellular environments. Our simulations indicate that: (i) in intracellular environments both fractal kinetics and mass action can be valid, the major determinant being the probability of reaction, (ii) the geometry and size of the intracellular surface on which reactions are occurring does not significantly affect the rate law, (iii) there are considerable differences between the rate laws valid in heterogeneous non-living structures such as crystals and those valid in intracellular environments. Deviations from mass action are less pronounced in intracellular environments than in a crystalline material of similar heterogeneity.

Fractals↗

PubMed1993

Enzymatic reactions of Clostridium difficile in aerobic and anaerobic environments with the RapID-ANA II identification system.

The RapID-ANA II anaerobic identification system (Innovative Diagnostic Systems, Inc., Atlanta, Ga.) was used to determine whether the incubation environment affects enzyme detection. Twenty strains of Clostridium difficile were tested in aerobic, anaerobic, and low-CO2 anaerobic incubation environments. The percentages of enzymes detected in reactions with the following substrates were noted in the three incubation environments: phenylalanine-beta-naphthylamide, aerobic, 0%; anaerobic, 35%; low-CO2 anaerobic, 35%; arginine-beta-naphthylamide, aerobic, 5%; anaerobic, 55%; low-CO2 anaerobic, 75%; pyrrolidonyl-beta-naphthylamide, aerobic, 5%; anaerobic, 65%; low-CO2 anaerobic, 65%. When the aerobic incubation environment was compared with either the anaerobic or the low-CO2 anaerobic incubation environments, the results were statistically different with respect to enzyme detection in reactions with the substrates listed above. The results for the anaerobic and low-CO2 anaerobic environments were not statistically different. The study was repeated twice. Statistical comparisons between the three environments were consistent with the results presented above, with the following exceptions. The aerobic and the anaerobic environments were not different in a reaction with phenylalanine-beta-naphthylamide in one of the runs, and there was no significant difference between the three environments in a reaction with arginine-beta-naphthylamide in another run. These results suggest that some of the enzymes used in the identification of clinical anaerobes appear to be inactive in an environment containing oxygen.

Aerobiosis↗

PubMed1988

Divergent selection for growth in Japanese quail under split and complete nutritional environments. 1. Genetic and correlated responses to selection.

Japanese quail were divergently selected for 4-wk body weight under two different nutritional environments. In one environment quail were divergently selected for high and low body weight (H and L) under a split diet (SD) with quail having the opportunity to self-select feed from high protein and high energy diets. In the other environment, quail were similarly selected (H and L) under a normal (28% protein) complete diet (CD). After 11 generations of selection, H-SD and H-CD lines were 48.9 and 49.7% higher in 4-wk body weight than controls. Quail from L-SD and L-CD lines were 46.5 and 45.4% lower in 4-wk body weight than controls. Realized heritabilities for 4-wk body weight were .36 +/- .03, .30 +/- .03, .52 +/- .02, and .47 +/- .03 for H-SD, L-SD, H-CD, and L-CD lines, respectively. Selection differentials were significantly higher in the SD than in the CD environment. Changes in 2-wk, adult body, and egg weight across generations paralleled that of the trait under selection (4-wk body weight). Selection also resulted in decreased hatchability and egg production with increased age to sexual maturity in both environments. The SD environment was determined to be a stress environment because of birds' inferior growth there compared with growth in the CD environment. Rate of growth, however, to reach adult body size was superior for L-SD quail once the stress environment was removed. There was also evidence that eggs were larger for quail in the SD than the CD environment.

Animals↗

PubMed1988

Plasmids in the environment.

Bacterial plasmids existed in bacteria before the antibiotic era but their presence was brought into prominence by the use of antibiotics which selected for antibiotic resistant strains. Subsequently, the range of genes carried on plasmids was shown to extend far beyond those coding for antibiotic resistance. Any consideration of plasmids in the environment, therefore, must include all plasmids whether or not they are genetically linked with antibiotic resistance. Antibiotic resistant bacteria may be found in the environment either by contamination with excreta from man and animals in which the strains were selected, or by their selection within the environment by antibiotics synthesized in situ or reaching the environment in an undegraded form in sewage from man and animals, or from industry. Other agents, also contaminating the environment, exert a selective pressure such as heavy metals in industrial effluents which select for metal resistance. This paper reviews the incidences and role of plasmids in various habitats including natural waters, soil, pastures, farm wastes, and human sewage from both hospitalised and other populations. Aspects of plasmid ecology, their biological role, and the transmissibility of genetic material between bacteria within the environment are considered. Two recent studies in Bristol, UK, are reported. The first was a genetic study on Escherichia coli isolates from calf slurry. Various DNA probes were used to determine the extent of gene exchange between the various serotypes within the natural environment. The second was a preliminary study to determine the stability of a recombinant plasmid, in a wild strain of Escherichia coli of pig origin, after its release into a semi-contained farm situation. It is now recognized that plasmids are widely distributed in bacterial populations in terrestrial and aquatic environments. Many have been detected by their carriage of genes coding for antibiotic or heavy metal resistance. Others, mainly cryptic in nature, have been demonstrated by plasmid profile studies on isolates from various habitats. Plasmids were shown to be present in a relatively few bacteria deposited in culture collections prior to the antibiotic era. Subsequently, the increased prevalence of R plasmids in bacteria in most ecosystems were due mainly to the selective pressure imposed by the use of antibiotics. This pressure may have been exerted either in the environment in which the strains were found or elsewhere, the environment subsequently being contaminated by antibiotic resistant bacteria.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed2001

The importance of the social environment for physically active lifestyle--results from an international study.

Physically active lifestyles are regularly associated with improved health and quality of life. Differences in lifestyles in society can partly be understood through the differences in the social and physical environment. This study examines the relationships between reported physical activity, and the extent of perceived support for physical activity in the physical and policy environment (e.g. facilities, programmes and other opportunities), and in the social environment. The data for the study come from a cross-cultural health policy study called MAREPS. In total, 3342 adults, 18 years or older, from six countries (Belgium, Finland, Germany, The Netherlands, Spain, Switzerland) were interviewed via telephone. Respondents were categorised as active or inactive according to self-reported physical activity. Social environmental factors and physical and policy environmental factors were also assessed. The analysis of the data was informed by social cognitive theory, although the study was not originally designed for this purpose. Sixty-eight percent of females and 70% of males were active. The proportions of active and inactive varied by countries to a great extent. The strongest independent predictor of being physically active was social environment. Those who perceived low social support from their personal environment (i.e. family, friends, school and workplace) were more than twice as likely to be sedentary compared to those who reported high social support from their personal environment. Specific knowledge of the programmes and actions for physical activity and sport was also a strong predictor of being active. A supportive physical and policy environment was not associated with participation in physical activity as strongly as had been anticipated. The variation between countries was stronger predictor of being active than the physical and policy environment variables. This study generates the hypotheses and raises the questions that in a preliminary way, there appears to be some relationships between aspects of physical and social environment and physical activity participation. However, future research is needed to refine and clarify this.

Adolescent↗

PubMed2006

Measuring physical and social environments in nursing homes for people with middle- to late-stage dementia.

OBJECTIVES: To evaluate measures of dementia care environments by comparing a special care facility (SCF) with traditional institutional facilities (TIFs). DESIGN: A cross-sectional comparative study of nursing home environments conducted as part of a longitudinal study on quality of life for residents with dementia. SETTING: Twenty-four traditional nursing homes and one special care facility. PARTICIPANTS: One SCF with six distinct environments, 24 TIFs with 45 distinct environments, and 88 family members. MEASUREMENTS: Therapeutic Environment Screening Scale-2+ (TESS-2+); Special Care Unit Environmental Quality Scale (SCUEQS), a subset of the TESS-2+ items; Composite Above Average Quality Score (CAAQS), a composite score of all items on the TESS-2+; and Models of Care Instrument (MOCI). RESULTS: The SCUEQS did not detect a significant difference between the SCF and the TIFs (30.0 vs 27.2, P = .28). The CAAQS detected a significant difference between the SCF and the TIFs, whereby the SCF environments were rated as having above-average quality in 71.4% of the domains, compared with 57.3% for the TIF environments (95% confidence interval (CI) for difference = 2.6-25.6%, P = .02). Using the MOCI, SCF families were 1.8 times as likely to rate the SCF as a home or resort versus a hospital as TIF families rating TIFs (95% CI for odds ratio = 1.5-2.1, P < .001). CONCLUSION: The TESS-2+ CAAQS differentiated between physical environments better than the more established SCUQES. The MOCI distinguished between environments using a more holistic approach to measurement. The availability of environmental measures that are able to discriminate between specialized and traditional long-term care settings will facilitate future outcome-based research.

Aged↗

PubMed1977

Response of the three main types of glial cells of cortex and corpus callosum in rats handled during suckling or exposed to enriched, control and impoverished environments following weaning.

The cell populations of the occipital cortex were examined in young rats subjected to different sensory experiences. In one series recently weaned animals were reared in enriched, impoverished or control environments. The enriched environment was obtained by keeping the animals among "toys" and other rats; the impoverished environment, by rearing the animals one per cage in a darkened, quiet room; and the control environment, by housing the animals three per cage under usual animal room conditions. Six recently weaned rats were kept in each environment for 30 days and ten, for 80 days. In a second series suckling rats were handled daily. Handling consisted of touching, holding and rubbing rat pups for 15 minutes per day during the first ten days after birth; twelve rats were studied, six handled and six unhandled controls. In the two series, the animals were sacrificed under anesthesia by perfusion with mixed aldehydes. Semithin epon sections of occipital cortex were stained with toluidine blue; neurons and the three main types of glia were enumerated. In addition, the thickness of the cortex was measured and the glial cells of corpus callosum counted in the animals exposed to the three environments for 80 days. Under the influence of the enriched environment, the occipital cortex enlarged, the number of oligodendrocytes increased over the controls by 27-33% in the 30- and 80-day groups and the number of astrocytes, by 13% in the 80-day group. Within the cortex, only certain layers showed the increase in glial numbers. In the corpus callosum, however, the numbers of glial cells did not differ from those in controls. In the animals exposed to the impoverished environment, neither the size of the cortex nor the number of oligodendrocytes and astrocytes differed from controls. The animals subjected to handling also showed evidence of cortical enlargement, but the only significant change in glial cells was a 12% increase in astrocytes. It is concluded that handling and enrichment produce changes in anatomical indices of neural function including depth of cortex and numbers of glial cells. The glial response was specific to the type.of manipulation since astrocytes were predominantly affected by handling and oligodendrocytes, by enrichment. The effect of handling on astrocytes may be attributed to the stimulation being applied at a time of astrocyte proliferation, whereas the effect of enriched environment on oligodendrocytes occurred at a time of active production of these cells. The differences in cell numbers were explained by changes in the rate of cell population growth; since the impoverished did not differ from the control animals, the changes probably consisted of growth acceleration in the enriched animals rather than diminution in the impoverished ones.

Animals↗

PubMed2000

Adaptation to spatially heterogeneous modifying and adaptive environments.

The development of an individual's phenotype is influenced by environmental factors (the modifying environment) which may differ from those factors (the adaptive environment) that decide on the adaptational value of the developed phenotype. The shapes of adaptationally optimal norms of reaction are therefore essentially determined by associations between these two environmental components together with the degree of adaptational sensitivity of the developed phenotypes. Two complementary aspects of optimality are accounted for: (a) environments can be optimal for a given norm of reaction and (b) norms of reaction can be optimal for a given environment. The results are obtained for random distribution of genotypes over environmental conditions and under the physiologically reasonable premise that fitness is a function of the costs of modification and adaptation. It turned out that the associations of adaptive and modifying environments are the primary sources of adaptational optimization. More specifically, it is shown that (i) independence between the two environmental components constitutes an adaptationally optimal environment only for norms of reaction in which all phenotypes are adaptively insensitive; (ii) if costs of modification do not depend on the environment, and if the two environmental components are not associated, adaptationally optimal norms of reaction can always be realized through phenogenetic invariance; (iii) as a rule, adaptively sensitive phenotypes developed under strong environmental associations necessitate phenogenetic plasticity for the optimal norm of reaction; (iv) a norm of reaction which is adaptationally optimal in its adaptationally optimal environment can always be realized through phenogenetic invariance, if costs of modification do not vary with the environment. These results reveal an important role of patterns of adaptive sensitivity of phenotypes, which may even surpass that of shapes of norms of reaction in adaptational processes.

Adaptation, Physiological↗

PubMed1985

Features of environment-dependent tolerance to ethanol.

Mice given multiple injections of ethanol in a standardized environment develop environment-dependent tolerance to the hypnotic and hypothermic effects of ethanol. These animals also demonstrate environment-dependent cross-tolerance to the hypnotic and hypothermic effects of pentobarbital. Examination of the levels of ethanol in the brain and blood at various times after injection of a test dose of ethanol, as well as the examination of the rate of disappearance of ethanol from the blood, indicated that environment-dependent tolerance could be explained by dispositional factors. On the other hand, mice rendered tolerant to ethanol by a liquid diet technique demonstrate tolerance that is not environment-dependent, and there is no alteration in ethanol levels in different environments for animals fed the liquid diet. When the animals in either paradigm are tested by injecting ethanol directly into the brain, tolerance is observed that is not dependent on the environment. Tolerance produced by these two different paradigms is apparently due to different adaptive strategies used by the animal. Environment-dependent tolerance is partially related to the ability of the animal to change the disposition of ethanol, while environment-independent tolerance may be entirely due to other factors, such as changes in neuronal sensitivity to ethanol.

Analysis of Variance↗