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PubMed2006

Behavioral phenotyping of transgenic and knockout mice: practical concerns and potential pitfalls.

New technologies in molecular genetics have dramatically increased the number of targeted gene mutations available to the biomedical research community. Many mutant mouse lines have been generated to provide animal models for human genetic disorders, offering insights into anatomical, neurochemical, and behavioral effects of aberrant gene expression. A variety of assays have been developed to identify and characterize phenotypic changes. In the behavioral domain, our phenotyping strategy involves a comprehensive standardized methodological approach that assesses general health, reflexes, sensory abilities, and motor functions. This assessment is followed by a series of complementary tasks in the specific behavioral domain(s) hypothesized to reveal the function(s) of the gene. Our multitiered approach minimizes intersubject variability by standardizing the experimental history for all animals, improves interlaboratory reliability by providing a clearly defined experimental protocol, and minimizes artifactual interpretations of behavioral data by careful preliminary assessments of basic behaviors, followed by multiple tests within the behavioral domain of interest. Despite meticulous attention to experimental protocol, attention to environmental factors is essential. Differences in noise, light, home cage environment, handling, and diet can dramatically alter behavior. Baseline differences in the behaviors of inbred strains used to generate targeted mutant mouse lines can directly influence the behavioral phenotype of the mutant line. Strategies aimed at minimizing environmental variability and contributions of background genes will enhance the robustness of mouse behavioral phenotyping assays.

Animal Husbandry↗
PubMed1999

Diversity and extinction in a lattice model of a population with fluctuating environment.

I study a lattice stochastic model of a mutating population sensitive to the influence of a fluctuating environment. The dynamics of the population stressed by linear and periodic disturbances is investigated. In agreement with previous studies of nonspatial models, I find a critical rate of change in the environmental variable beyond which the population becomes extinct, and I show explicitly that the presence of space in the model can affect the critical rate. Further, I study the diversity defined as the total number of different cell types present in the lattice as a function of intensity and frequency of the environmental disturbance. If the disturbance becomes fast and intense the population becomes extinct. Interestingly, I find that for moderate stresses the diversity increases with the intensity and frequency of disturbance. The transition between large diversity and extinction is sharp, implying that the populations with high diversity are generally the ones closest to the extinction threshold. When subjected to colored noise of increasing intensity the system grows in diversity but at the same time is more likely to become extinct.

Biophysical Phenomena↗
PubMed2003

Modeling habitat suitability for moose in coastal northern Sweden: empirical vs process-oriented approaches.

Habitat models may provide viable tools for co-management of large ungulates and forest resources, yet their applicability has not been comprehensively evaluated in managed forest. We examined 2 inherently different approaches to model the relative winter habitat suitability for moose (Alces alces) in the coastal area of northern Sweden. An empirical approach based on GPS positions of 15 female moose was used to scrutinize the assumptions and functional mechanisms of a process-oriented, conceptual approach, based on published material on the species' preferences for habitat components related to food and cover. For both model approaches habitat was described using estimates of forest-stand characteristics based on satellite imagery. The empirical model also included variables relating to topographic properties of the landscape as well as distances to landscape features. The output from both models was a habitat suitability index (HSI) score, enabling the models to be compared with each other. The models showed different results, highlighting the need to include the spatially explicit distribution of environmental variables in future conceptual, process-oriented models.

Animals↗
PubMed1983

Self-monitoring and sex as moderator variables in the statistical explanation of self-reported marijuana and alcohol use.

Self-monitoring and sex are examined as likely moderators of some of the known effective predictors of self-reported use of marijuana and alcohol. The theory of self-monitoring implies that in comparisons between low and high self-monitors, dispositional predictors account for more of the variance in reported use among low self-monitors and environmental predictors account for more of the variance among high self-monitors. With the two classes of predictors established via principal-components analysis and with subgroups defined by scores on Snyder's Self-Monitoring Scale, data from 807 college students showed that self-monitoring does not affect the action of either dispositional or environmental predictors. Thus, the self-monitoring construct promises explanatory leverage that in these tests, the scale is not able to deliver. When subgroups are defined by sex, analyses of reported alcohol use yield small but significant moderator effects: Women's use is more predictable from environmental variables, whereas men's use is more predictable from dispositional variables. These effects are consistent with the conclusions of recent meta-analyses of results from studies of sex differences in conformity to group pressures.

Alcohol Drinking↗
PubMed1998

Seasonal variations in hospital admissions for affective disorders by gender and ethnicity.

Hospital admission statistics for depression and mania have shown significant seasonal patterns. The present investigation was conducted to establish the pervasiveness of the impact of seasons on mood disorder presentation at Birmingham (52 degrees North) by gender and ethnicity. Non-mood disorder admissions were examined as a control to determine the specificity of any seasonal variation to affective illness. Case notes for 992 admissions, during January-December 1995 inclusive, to an inpatient unit were reviewed retrospectively. Admission data were broken down by gender and into three ethnic groups: Asian, white and black. Seasonality in admissions for depression, bipolar disorder and non-mood disorders was tested by gender and ethnicity. Admission frequencies for depression showed significant seasonal pattern, with the incidence of depression being highest in winter. Total admissions, bipolar and non-mood disorders did not show any significant seasonal variability. A gender effect was evident on seasonality of admissions for affective illness, with significant winter peak for depression and summer peak for bipolar disorder in women only. The Asian group was the only ethnic group that showed significant seasonal variation in depression, with a greater number of depressive episodes in winter. Environmental variables were related significantly to the incidence of mood disorders. Specific seasonal effect for affective illness was evidenced by the non-existence of seasonality in other psychiatric disorders. The reverse seasonal pattern for depression and mania suggests a maladaptive response of vulnerable individuals to specific functions of seasons.

Adult↗
PubMed2005

Factors that shape seed mass evolution.

We used correlated divergence analysis to determine which factors have been most closely associated with changes in seed mass during seed plant evolution. We found that divergences in seed mass have been more consistently associated with divergences in growth form than with divergences in any other variable. This finding is consistent with the strong relationship between seed mass and growth form across present-day species and with the available data from the paleobotanical literature. Divergences in seed mass have also been associated with divergences in latitude, net primary productivity, temperature, precipitation, and leaf area index. However, these environmental variables had much less explanatory power than did plant traits such as seed dispersal syndrome and plant growth form.

Biological Evolution↗
PubMedDate not supplied

Induced plant signaling and its implications for environmental sensing.

The sophisticated chemical responses of plants to environmental stimuli have profound implications for the development of remote sensing systems. Recent advances in the investigation of these responses have demonstrated that plants can be developed as reliable reporters of numerous environmental stimuli including soil and water conditions, light levels, temperature, mechanical damage, insect feeding, exposure to pathogens--including those that affect animals and humans--and exposure to airborne chemicals. Researchers are just beginning to understand the full range of plant phenotypic responses to these and other stimuli. These responses often have measurable physiological and molecular components that are readily observed. Other responses (e.g., internal biochemical changes) are less readily assayed, although sensing devices are being developed. Plant volatile emission "signatures" are particularly promising modes of plant reporting that can provide highly specific information regarding a diverse range of environmental variables on short time scales, but new approaches are needed for sensing these responses remotely. Modern molecular techniques promise to allow us to refine plant sensing and reporting, greatly enhancing the potential utility of plants as "sentinels." Continued basic research aimed at characterizing the physiological, biochemical, and molecular responses of plants to environmental stimuli (including airborne chemicals, insects and pathogenic microbes) are essential to achieving that promise.

Environmental Monitoring↗
PubMed2001

The effects of trawling on the benthic fauna of the Gulf of Nicoya, Costa Rica.

Four van Veen grab replicates where collected to sample macrofauna (organism retained on a 500 micron mesh sieve) at four stations in the Gulf of Nicoya, during October 24, 1997, January 16 and April 30, 1998. This information was used to search for any effects of trawling on the benthic fauna. Two stations where located in a trawled area, and two stations where in a protected area. Diversity (H') varied from 2.01 to 3.52 in the trawled area and from 2.13 to 2.78 in the protected area. Diversity was generally higher in the trawled area, and this was in contradiction to what we would have expected from other studies where the trend has been that trawling reduces diversity. Brittlestars and lancelets seemed to be the groups mostly harmed by the trawling, while amphipods where more abundant in trawled areas. The multivariate analyses did not reveal the patterns of faunal change as well as we hoped. This is surely because of our lack of more replicate samples. The multivariate analyses are easily confounded when few sites are analyzed. We have found differences in the type of fauna found in trawled and protected areas and, considering the differences in environmental variables in our stations and our lack of replication, this indicates that there are differences and a larger investigation is in order to reveal its magnitude.

Animals↗
PubMed1992

Performance in quasi-firms: an example from the Community Clinical Oncology Program.

In this analysis, the authors examined the effects of different sets of process, structure, and environmental variables on the performance of the CCOP as a quasi-firm. Specifically, they distinguished between internal organizational processes, structural, and size characteristics of the CCOP and the organizational environment created by prior NCI program experience and the relationship within the quasi-firm. The analysis revealed that these sets of organizational and environmental characteristics have differential effects on treatment accrual. The strongest predictors are those associated with the quasi-firm relationship between the CCOP and its chosen research bases. Any definitive policy implications for the design of organizational network relationships--especially the CCOPs--will require further analysis. Particular attention needs to be given to the longitudinal nature of the relationships and the ability of these organizational and environmental factors to affect other aspects of performance. Several points have been made within this initial assessment. First, the structural character of the CCOP and its relationship to its organizational environment are important factors affecting accrual performance. The subtleties of this multivariate model are not as important as simply demonstrating that the various internal and external characteristics of these organizations as quasi-firms simultaneously affect their ability to accrue patients to clinical trials. Secondly, the importance of research base relations, and particularly the significant role of nurses, needs to be emphasized. While CCOPs were originally designed as a network of physicians and hospitals, it appears that an infrastructure of professionally active nurses working within a larger organizational environment is critical to success--at least as defined by accrual to treatment protocols. Finally, the failure of prior experience with other NCI community programs to affect CCOP accrual performance suggests that such experience does not assure "organizational learning" that may enhance performance. This suggests that CCOPs can be designated de novo to maximize performance without necessarily having to undergo a developmental or experiential phase involving community cancer programs to be effective. However, the authors suspect that another method of characterizing experience may produce different results. Further analyses of these data will test these results against other measures of CCOP performance. Specifically, attention will be given to whether this same set of characteristics is predictive of accrual to cancer control research protocols. Similarly, these same organizational characteristics may or may not be associated with other dimensions of CCOP performance such as changes in physician practice patterns and/or levels of institutionalization of the CCOP within its local community.(ABSTRACT TRUNCATED AT 400 WORDS)

Clinical Trials as Topic↗
PubMed1991

A theoretical model for understanding dentists' behavior in treating patients with AIDS.

This paper attempts to expand on a model from the theory of reasoned action to help us identify and better understand the reasons dentists do or do not treat dental patients with, or at risk for, AIDS. We propose in the model that the dentist's actual behavior in treating dental patients with, or at risk for, AIDS, in his or her practice is a function of both his or her intention to treat such patients and his or her nonvolitional factors relevant to the behavior. The dentist's intention to treat patients with AIDS or HIV infection, or those belonging to high risk groups, is influenced by two belief components: (1) attitudinal variables, which are the dentist's beliefs about the consequences of treating such patients and the value that these consequences have for him or her; and (2) normative variables, which indicate the dentist's perceptions of how his or her reference groups view the treatment of such patients in his or her practice and his or her motivation to comply with those views. Finally, both the two belief components and the nonvolitional factors are affected by the personal characteristics and the environmental variables.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Neural correlates of genetically determined and acquired color preferences in quail chicks.

The uptake of tritiated 2-deoxyglucose (2-DG) was examined in brains of artificially selected and unselected control quail, in relation to genetically and environmentally variable early approach preferences of a colored stimulus. The data indicated high labeling in the tectofugal and low labeling in the thalamofugal projection systems in birds exhibiting preference for the light wavelength characteristics of the stimulus in independently tested choice situations. The differential labeling was observed regardless whether the stimulus preference was genetic or environmental in origin (i.e. whether it was exhibited by artificially selected and experientially naive or by unselected and imprinted control chicks). Chicks responding to the stimulus after prior imprinting experiences also exhibited high labeling in the intermediate medial portions of the neostriatum and hyperstriatum ventrale.

Animals↗
PubMed2006

Benthic recovery during open sea fish farming abatement in Western Mediterranean, Spain.

Fish farming is an important source of organic matter input in coastal waters, which contributes to eutrophication. In this study, the macrofaunal benthic community was studied after the cessation of fish farming with the aim of improving our understanding of benthic succession and sediment recovery in a marine ecosystem. The results showed that the best environmental variables for assessing organic pollution were acid-volatile sulfides (AVS) and redox potential. Succession and recovery was best explained by macrofaunal analysis based on community composition as well as on trophic groups. The patterns of recovery differed between each impacted station. For this reason, succession could not be accurately predicted due to the unique environmental parameters and the singular community functional structure of each location. The Azti Marine Benthic Index (AMBI) proved its validity for assessing pollution but did not distinguish between successional stages.

Ammonia↗
PubMed1990

Long-term stability of the place-field activity of single units recorded from the dorsal hippocampus of freely behaving rats.

Over 90% of all spontaneously active hippocampal pyramidal cells in freely moving rats signal the animal's spatial position by reliably changing their firing rate each time the animal enters a given place within an environment. This place-field activity exhibits plasticity when specific environmental variables are manipulated. Indeed, the hippocampus is perhaps best known as a system that serves as a model of neuronal plasticity. Although place-field activity has previously been examined only over relatively short experimental sessions, this behavioral correlate of hippocampal functional activity has been assumed to exhibit stability rather than plasticity in the absence of environmental changes. The present study shows that hippocampal neurons have stable place-field correlates that persist over very long periods of time. Single-unit activity was chronically recorded from the dorsal hippocampus of rats foraging repeatedly in a stable spatial environment. The location of the place fields of all units were stable over all time periods tested, for intervals up to 153 days in duration. The consistency of the information conveyed by this single-unit activity in a fixed spatial environment indicates that stability of neuronal activity may be as important as plasticity in the integrated processing of information that occurs in the hippocampus and throughout the nervous system.

Action Potentials↗
PubMed1995

A field study of the ventilatory response to ambient temperature and pressure in sport diving.

This study reports on the relationship between minute ventilation (VE) and environmental variables of temperature (T) and pressure (P) during open water diving. The author conducted a total of 38 dives involving either a light (20 dives) or a moderate (18 dives) level of physical activity. Within each of these groups, P and T taken together accounted for about two thirds of the variance in the VE data. A very significant increase in VE was observed as T decreased (1 < T(degrees C) < 22), and the magnitude of this increase at a given pressure level was similar in the 'light' and the 'moderate' data sets. A second order observation, particularly notable at lower temperature, was the decrease in VE with increasing pressure under conditions of light work. Empirical functions of the from VE = A+B/P n[1 + exp(T - 8)/10], where A, B, and n are adjustable variables, could accommodate both data sets over the whole range of T and P. These results are the first obtained under actual diving conditions to provide evidence for interactions between P, T, and VE. Understanding the physiological mechanisms by which these interactions occur would assist in appreciation of the limitations imposed on scuba divers by the environmental conditions as they affect their ventilatory responses.

Adult↗
PubMed2006

Biological responses to environmental forcing: the linear tracking window hypothesis.

Determining the relative contributions of intrinsic and extrinsic processes to the regulation of biological populations has been a recurrent ecological issue. Recent discussions concerning ecosystem "regime shifts" again raise the question of whether population fluctuations are mainly controlled by external forcing. Results of nonlinear time series analyses indicate that pelagic populations typically do not passively track stochastic environmental variables. Rather, population dynamics are better described as nonlinear amplification of physical forcing by biological interactions. However, we illustrate that in some cases populations do show linear tracking of the physical environment. To explain why population dynamics can sometimes be linear, we propose the linear tracking window hypothesis: populations are most likely to track the stochastic environmental forcing when their generation time matches the characteristic time scale of the environmental signal. While our observations follow this hypothesis well, our results indicate that the linear tracking window is a necessary but not a sufficient condition.

Animals↗
PubMed1987

Obesity in black women.

The marked excess of obesity among black women in the United States poses several interesting questions which provide the framework for this review: Is the apparent high prevalence of obesity in black women a valid finding? If so, does it show the expected disease and disease risk associations? Can the contributory genetic and environmental variables be identified? Regarding the validity issue, the high prevalence of obesity in black women seems to be neither artifactual nor primarily an indirect effect of socioeconomic status. On the issue of racial comparability of disease risks among women, the available evidence is less conclusive. Obesity appears to have qualitatively similar health consequences for black women and white women but may be less strongly related to some disease risks (for example, hypertension) in black women than in white women. Obesity risks of black women may, however, be enhanced by the presence of multiple risk factors. On the question of causes, no clear mechanism for the excess obesity in black women can be identified. There is some evidence to support hypotheses based on dietary, lifestyle, and metabolic influences. Genetic factors cannot be ruled out. Several relevant future research possibilities can be suggested. Epidemiologic studies of both genetic and environmental influences in female obesity are needed. Studies among black females might further specify patterns of body weight and body fat distribution according to degree of European admixture and developmental variables such as caloric exposure in utero and in early infancy. Studies to establish more clearly the relative risks of various health outcomes for obese black women are needed to assist in setting public health priorities. For example, what are the attributable and absolute risks of overweight or obesity compared with other risk factors that are potential intervention targets? Studies are needed to define effective means of preventing and treating obesity among black women. Effective interventions are likely to be culture-specific. Definitive comparisons of black women and white women on environmentally mediated aspects of obesity might contribute to models of obesity in the general population and might also elucidate points at which black women and white women diverge. For example, short-term prospective studies are needed to better specify the natural history of weight gain and weight loss among females of both races during critical periods such as adolescence, post partum, lactation and post lactation, and during major life stresses.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed2005

Common variations in the pretest environment influence genotypic comparisons in models of anxiety.

The behavioral characterization of rodent strains in different studies and laboratories can provide unreplicable results even when genotypes are kept constant and environmental control is maximized. In the present study, the influence of common laboratory environmental variables and their interaction with genotype on the results of behavioral tests of anxiety/emotionality were investigated. To this end, the inbred rat strains Lewis (LEW) and spontaneously hypertensive rats (SHR), which are known to differ for numerous emotionality-related behaviors, were tested in the open field (OF), elevated plus maze (EPM) and black/white box (BWB), while three environmental factors were systematically controlled and analyzed: (1) the experimenter handling the animal (familiar or unfamiliar); (2) the position of the home cage (top or bottom shelf of the rack) and (3) the behavioral state of the animal immediately before the test (arousal or rest). Experimenter familiarity did not alter the behavior of rats in the OF. Cage position, on the other hand, influenced the behavior in the OF and BWB, with rats housed in top cages appearing less anxious than those housed in the bottom. In the BWB (but not in the OF), these effects were genotype dependent. Finally, the behavioral state of the animals prior to testing altered the results of the EPM in a strain-dependent manner, with some anxiety-related genotypic differences being found only among rats that were aroused in their home cages. This study showed that common variations in the laboratory environment interact with genotype in behavioral tests of anxiety/emotionality. Recognizing and understanding such variations can help in the design of more effective experiments.

Analysis of Variance↗
PubMed1980

Stuttering: a disorder of movement.

Based on the data and discussion in the two preceding papers a preliminary model for disfluency is proposed. Stuttering is identified as movement patterns associated with perceptually judged disfluencies. It is suggested that the speech structures operate within certain ranges of variability in terms of their movement parameters and interarticulator temporal and spatial relations. This variability may be influenced by emotional, perceptual and/or physiological events. When the "normal" ranges are exceeded, the afferent nerve impulses generated alter the gains of associated brainstem reflexes. Altering of the reflex gains throws the articulatory system out of balance and a breakdown in behavior occurs, often manifested as oscillations or static positioning. The influence of physiological and environmental variables on neuromotor processes leading to these patterns is emphasized. The model suggested has been developed from inferences from movement patterns of the upper articulators. Thus, the patterns discussed involve these structures. It is suggested, however, that an understanding of the many behaviors associated with stuttering will be understood only by analyzing the behavioral and neurophysiological interactions among the respiratory, laryngeal, and supraglottal structures.

Animals↗