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PubMed1987

Differences in biological characteristics of two strains of the cestode Hymenolepis diminuta.

Biological characteristics of infectivity, growth rate and fecundity of Hymenolepis diminuta isolated from wild Rattus rattus in Japan were compared with parasites of Texas origin maintained for several generations in this and many other laboratories in laboratory bred Rattus norvegicus. The timing of development and maturation was similar in parasites from both sources, but the mean parasite dry weight was less and the mean egg production lower in Japanese parasites in both single and multiple infections. The differences persisted over 10 weeks in single infections, and were unaffected by rat strain. In all experiments there was much greater variation and heterogeneity in the biological characteristics of the Japanese parasites. It was concluded that the Texas parasites were better adapted to R. norvegicus and in the course of adaptation had become more homogeneous, and that the difference between the parasite strains had a complex genetic basis. Some Japanese parasites of the early isolated generations failed to produce normal eggs, but the proportion of these decreased in later generations. However, selected individual Japanese parasites whose egg production was equal to that of parasites of Texas origin did not produce offspring of larger mean size or higher mean fecundity, and heterogeneity of these characteristics was maintained. In the intermediate host, the mean number of cysticercoids of the Japanese isolate per beetle was higher than that of the Texas strain in Tribolium confusum but lower in Tenebrio molitor. The greater heterogeneity exhibited by Japanese parasites and the genetic basis of the strain difference are discussed with particular reference to geographical isolation, differences in definitive hosts and co-evolution of wild and laboratory host and parasite populations.

Animals↗
PubMed2003

Perspective: Evolution and detection of genetic robustness.

Robustness is the invariance of phenotypes in the face of perturbation. The robustness of phenotypes appears at various levels of biological organization, including gene expression, protein folding, metabolic flux, physiological homeostasis, development, and even organismal fitness. The mechanisms underlying robustness are diverse, ranging from thermodynamic stability at the RNA and protein level to behavior at the organismal level. Phenotypes can be robust either against heritable perturbations (e.g., mutations) or nonheritable perturbations (e.g., the weather). Here we primarily focus on the first kind of robustness--genetic robustness--and survey three growing avenues of research: (1) measuring genetic robustness in nature and in the laboratory; (2) understanding the evolution of genetic robustness: and (3) exploring the implications of genetic robustness for future evolution.

Adaptation, Biological↗
PubMed1989

Alcoholism and family factors. A critical review.

This chapter provides a critical review of empirical research in the area of alcoholism and family psychosocial factors. The review describes the early conceptualizations of the alcoholic family system as a unitary phenomenon and summarizes a series of laboratory studies using simulation games that sought to identify salient characteristics of alcoholic family interaction. The chapter traces the evolution of family psychosocial research and highlights the current interest in the field in articulating alcoholic family typologies. The discussion focuses on two major bodies of research: (1) a collection of studies that form the basis for a theory of alcoholism and family development; and (2) an ongoing series of projects that address the relationship between different patterns of alcohol consumption and family interaction. Topics addressed in the research include the possible adaptive functions of alcohol in family systems, the relationship between phasic drinking patterns and family regulatory dimensions, and the effects of family response style on long-term family functioning and intergenerational transmission of alcoholism.

Alcohol Drinking↗
PubMed2002

Noninvasive testing in the clinical laboratory.

We have chosen to provide a brief review of only three of the numerous existing, emerging or future applications of novel technologies that provide noninvasive testing. Clinical laboratory testing over the recent decades has been characterized by a remarkable increase in the variety and volume of [figure: see text] information made available to assist physicians in the practice of medicine. Among current trends that facilitate prompt delivery of results, noninvasive testing holds great promise. Technologies that already exist or that have not yet been developed may extend the opportunities to exploit this approach. Noninvasive testing has other obvious attractive features; safety, painlessness and adaptability to special care situations. Our profession may well enjoy additional vitalization from the further evolution of this facinating and important field.

Blood Glucose↗
PubMed2001

Amplification of mutator cells in a population as a result of horizontal transfer.

Mutator cells that lack the mismatch repair system (MMR(-)) occur at rates of 10(-5) or less in laboratory populations started from wild-type cells. We show that after selection for recombinants in an interspecies mating between Salmonella enterica serovar Typhimurium and Escherichia coli, the percentage of MMR(-) cells rises to several percent of the recombinant population, and after a second successive mating and selection, greater than 95% of the recombinants are MMR(-). Coupling a single cross and selection with either mutagenesis or selection for spontaneous mutants also results in a dramatic increase in MMR(-) cells. We discuss how horizontal transfer can result in mutator strains during adaptive evolution.

Base Pair Mismatch↗
PubMed2003

Duplication and selection in the evolution of primate beta-defensin genes.

BACKGROUND: Innate immunity is the first line of defense against microorganisms in vertebrates and acts by providing an initial barrier to microorganisms and triggering adaptive immune responses. Peptides such as beta-defensins are an important component of this defense, providing a broad spectrum of antimicrobial activity against bacteria, fungi, mycobacteria and several enveloped viruses. Beta-defensins are small cationic peptides that vary in their expression patterns and spectrum of pathogen specificity. Disruptions in beta-defensin function have been implicated in human diseases, including cystic fibrosis, and a fuller understanding of the variety, function and evolution of human beta-defensins might form the basis for novel therapies. Here we use a combination of laboratory and computational techniques to characterize the main human beta-defensin locus on chromosome 8p22-p23. RESULTS: In addition to known genes in the region we report the genomic structures and expression patterns of four novel human beta-defensin genes and a related pseudogene. These genes show an unusual pattern of evolution, with rapid divergence between second exon sequences that encode the mature beta-defensin peptides matched by relative stasis in first exons that encode signal peptides. CONCLUSIONS: We conclude that the 8p22-p23 locus has evolved by successive rounds of duplication followed by substantial divergence involving positive selection, to produce a diverse cluster of paralogous genes established before the human-baboon divergence more than 23 million years ago. Positive selection, disproportionately favoring alterations in the charge of amino-acid residues, is implicated as driving second exon divergence in these genes.

Amino Acid Sequence↗
PubMedDate not supplied

[The sociality syndrome. A comparative study of the behavior of gerbils].

To explain the evolution of sociality the authors propose the hypothesis that every social interaction is based on the contest. The synergetic nature of any interaction determines the permanent involving partners in the contests and leads to increasing social pressure within community. The contestants' interactions inhibit an activity in one of the partners. Two possible evolutionary strategies of adaptation to increasing social density are: 1) an increase in resistance to the activity inhibition; 2) a retaining in memory the results of inhibition, i.e. reducing of ability to restore inhibited activity. Three species of gerbils (Gerbillidae): Mongolian (Meriones unguiculatus), Libyan (M. libycus), and midday gerbil (M. meridianus) were compared. Being similar in their ecology and behavioural repertoire three species differ strongly in extent of sociality: the highest in Mongolian gerbil and the lowest in midday one. The duration of social acts in laboratory groups of gerbils as well as frequency of acts delaying conflicts under natural conditions were assumed to correlate with increase in resistance to social pressure. Both parameters were higher in mongolian and libyan gerbils. The data on dynamics, asymmetry, and stability of social relations indicates more stable retaining in memory the results of interactions in Mongolian and Libyan gerbils than in midday ones but the latter restore inhibited activity more quickly. In the laboratory groups where the available space is compressed the midday gerbils maintain population at a level not lower than Mongolian ones and much higher than M. libycus. Moreover aggression within the group of midday gerbils doesn't result in rapid population decrease as in other two species.

Agonistic Behavior↗
PubMed2006

[Blood screening of benzodiazepines and tricyclic antidepressants. Results of 5 years of interhospital controls].

Pro bio Qual Association of Lyon have proposed a control which include the control for detecting benzodiazepines (BZD) and tricyclic antidepressants (ADT) since 2000. With this control, we have evaluated the specificity and the sensitivity of techniques used. We have tested the maprotiline reactivity too (tetracyclic antidepressant). We report results achieved with different immunoassay methods and their performances: specificity and sensitivity. The number of laboratories which realize these analyses is constant: these laboratories are hospital laboratories. Two methods are most common used: the fluorescence polarization immunoassay (FPIA) and the enzyme multiplied immunoassay test (EMIT). The evolution of these techniques does square with the evolution of chemistry analysers used in hospital laboratories. For the BZD, the specificity is good. For the ADT, carbamazepine at low concentration (5 mg/L) gives a positive result with FPIA Abbott assay; carbamazepine at high concentration (25 mg/L) gives a negative result with EMIT assay; phenothiazines give a positive response. For the BZD, the analyser Integra gives best results of sensitivity. Results of sensitivity obtained with the kit EMIT DAU are better than results obtained with the kit EMIT Serum. For the ADT, results of sensitivity obtained with FPIA Abbott assay seem better; the adaptation of EMIT assay on Integra analyser gives less good results. The reactivity for the BZD is very different: we can ignore a severe intoxication with alprazolam or lorazepam (response << cut off) but we can give a positive result for a therapeutic concentration of diazepam for example. With ADT, we haven't the same problem. But the reactivity for nortriptyline is less good than the reactivity for amitriptyline. So we should use a "cut off" concentration which corresponds to the best sensitivity and the best specificity.

Antidepressive Agents, Tricyclic↗
PubMed2000

[Biological effects of nonionizing radiation: low frequency electromagnetic fields].

This article reviews various studies on effects of electric and magnetic fields of extremely low frequencies on human health and gives an overview of residential and occupational exposure to different sources, currently established exposure limitations, and protection measures. Throughout the evolution biological systems adapted to natural electric and magnetic fields. Only hundred years ago human exposure to radiation was limited to electric and magnetic fields arising either from extraterrestrial or terrestrial sources, yet both natural. For the past fifty years there has been large growth of artificial sources of electric and magnetic fields, especially with frequencies of 50 and 60 Hz (power generating and distribution systems). The concern about long-term exposure to artificial fields and possible adverse effects on human health has been entirely justified and led to numerous intensive epidemiological and laboratory studies. Results of several epidemiological studies confirm the connection between exposure to electric and magnetic fields of extremely low frequencies (up to 300 Hz) and increased risk of leukemia and brain tumor in children and adults. In addition, the risk of breast cancer in occupationally exposed population has increased. Laboratory studies on animal models, in vitro systems, and human volunteers did not confirm this connection. There is a growing interest in investigation of other possible adverse health effects such as neurodegenerative diseases (Alzheimer's disease and other forms of dementia, amyotrophic lateral sclerosis), cardiovascular disorders (arrhythmias and acute myocardial infarction), psychiatric disorders, and electrosensitivity.

Animals↗
PubMed1985

Evolve III: a discrete events model of an evolutionary ecosystem.

Evolve III is a discrete events model of an evolutionary ecosystem. The model includes three levels of organization: population, organism and genetic structure. Each of these components was modeled independently, so that selective replacement of subsystems can be used to create families of models capable of testing alternative hypotheses about the real system. To demonstrate the use of the model we describe an experiment on the relationship between adaptability of populations and the variability of the environment. Populations cultured in a constant environment usually dominated those cultured in a variable environment when both were placed in a variable environment at an early stage of development, whereas the opposite is the case at later stages of development. This agrees with experiments on laboratory microcosms and lends credence to the potential predictive value of the model.

Biological Evolution↗
PubMed2005

Proceedings of the SMBE Tri-National Young Investigators' Workshop 2005. Molecular genetics of natural populations.

Significant progress in evolutionary genetics has been made by studying, on the one hand, patterns of DNA sequence polymorphism and, on the other, genetic architecture of complex adaptive traits. However, connections between nucleotide variants under selection and adaptively relevant phenotypes are missing. Such connections can be established using precise gene replacement. We review the recent successful introduction of this technique to the analysis of two evolutionarily interesting loci--Odysseus and desaturase2. Both genes have subtle phenotypes that nevertheless could be identified using gene replacement, demonstrating that effects of naturally occurring alleles can be measured in the laboratory. This is an important first step in connecting statistical signatures of selection with adaptation in nature. More candidate genes involved in adaptation, for example, through cloning of genes responsible for reproductive isolation, now need to be identified. Molecular genetic manipulation, DNA polymorphism analysis, and field studies then have to be integrated to provide fresh insights into the mechanisms of evolutionary change.

Alleles↗
PubMed1967

Voluntary hypothermia in reptiles.

Studies on lizards in laboratory thermal gradients which are not shut down at night reveal complex thermoregulatory behavior. Maintenance of the high, characteristic levels of body temperature known for active lizards may be abandoned. Low levels, which incapacitate the lizards, are seleted. Evidence of complex responses of the "thermostat" at a reptilian level of organization

Adaptation, Physiological↗
PubMed1975

Diversity and adaptation in rodent copulatory behavior.

Copulatory patterns of muroid rodents provide an ideal locus for comparative behavioral research. Such patterns are highly stereotyped within and between the individuals of a given species, variable across species, readily elicited in the laboratory, and of great biological significance. Detailed behavioral comparisons of a broad range of muroid species have revealed extensive behavioral diversity that was not anticipated from research confined to laboratory rats. Various muroid species display postejaculatory compulations without sperm transfer, locking, thrusting, and other behavioral patterns. This behavioral diversity appears not to be the result of a simple linear pattern of evolutionary history. Rather, patterns appear to have evolved repeatedly in response to particular selective pressures acting on particular species. While understanding of the adaptive significance of these behavioral patterns remains rudimentary, important beginnings have been made.

Animals↗
PubMed1992

[Specifics of the epidemiology of urinary schistosomiasis in Mauritius].

Early observations on this disease were made in Mauritius by Chapotin (1812) before the discovery of Schistosoma haematobium. Bulinus cernicus, the snail intermediate host, one of the nine species within the B. forskali group, is restricted to the island and the disease is not occurring in the neighbouring islands of La Reunion and Rodrigues. Under laboratory conditions, the snail susceptibility to the Mauritian strain of S. haematobium has been demonstrated. But the infection rate of the snail remains very low and the transmission of the disease is sporadic except in three foci. Its occurrence is not linked with agriculture or irrigation but is closely related to other man/water contacts in the rivers. Without clinical significant signs, the disease, quite different of the historic description, is largely underestimate. The snail is well adapted to the climatic conditions on Mauritius with a remarkably resistance to long drought periods. In fact, distribution of snail and evolution of population size fluctuate dramatically. Canalization and drainage of rivers, streams and marches since the beginning of malaria outbreak, widespread use of pesticides during the antimalaria spraying campaigns, only overhead irrigation, permanent maintenance of the lined canal system, induced many ecological constraints to possible snail habitats. Without animal reservoir of infection, control of urinary schistosomiasis or even its eradication looks feasible through a large school case-finding eventually associated with mollusciciding activities in the main foci.

Animals↗
PubMed2006

Quantitative analysis of dental microwear in threespine stickleback: a new approach to analysis of trophic ecology in aquatic vertebrates.

1. The threespine stickleback Gasterosteus aculeatus is an important model organism in studies of genomic and phenotypic evolution, adaptation and speciation. Fossil Gasterosteus offer the potential to test models derived from studies of extant fishes over true evolutionary time-scales. Competition for food resources, for example, plays an important part in stickleback speciation, causing divergence in food gathering traits and ecological character displacement, but it is not possible to test this model in fossils because evidence of diet is almost never preserved. 2. We demonstrate here that quantitative analysis of dental microwear, a technique previously applied only to mammals, provides a reliable guide to the dietary preferences of stickleback. Teeth from stickleback raised under laboratory conditions exhibit microwear patterns that vary systematically according to substrate coarseness and whether fishes feed on Daphnia within the water column, or on chironomid larvae from the bottom. Furthermore, microwear data exhibit a progressive shift in their distribution that tracks differences in experimental feeding treatments. 3. Microwear in wild populations also exhibits a relationship with feeding. In blind assessments of trophic niche based on microwear patterns we were able to correctly assign all but one equivocal population to trophic group. Microwear data from wild stickleback exhibit a shift in distribution comparable with that observed across the range of treatments in the laboratory and these allow populations to be ranked according to the degree to which they approach fully benthic or fully limnetic feeding. 4. Our results demonstrate that microwear has the potential to be a powerful tool in the analysis of fish trophic ecology, particularly in the analysis of species pairs and niche differentiation. It has advantages over the trophic snapshot provided by analysis of stomach contents in that microwear reflects feeding and food preferences over a longer period of time, and can be applied where these data are unavailable. Furthermore, it is applicable to extinct organisms and fossils, allowing the role of trophic ecology, niche partitioning and competition over evolutionary time-scales to be investigated for the first time.

Animals↗
PubMed2003

[Value of percutaneous core needle biopsy in the investigation of a suspected bone tumor].

PURPOSE: To Determine the value of percutaneous core needle biopsy in the investigation of a suspected bone neoplasm. MATERIAL AND METHODS: We performed a retrospective study of 91 core needle biopsies performed between May 1995 and October 2001. Patients were excluded if they had a known primary carcinoma or if an infection was suspected by clinical, physical or laboratory findings. The results were correlated to the analysis of the surgical piece or, for the 28 patients who did not undergo surgery, to the clinical evolution over more than 12 months. RESULTS: The final diagnosis was metastasis in 29 cases, primary bone tumor in 36 cases and benign lesions in 25 cases. Sensitivity was 92.3% and specificity was 97.4%. For primary malignant bone tumors, results respected histology features and grade in 79.2%. In cases of mistake, because of the correlation of these results to the clinical and radiological context, the treatment of the bony malignant lesions were adapted in 95.8% of cases. Only one major complication was reported in these 91 biopsies. CONCLUSION: First intention core needle biopsy, confronted with radio-clinical context seems to have a place in the evaluation of bone lesions when a tumor is suspected. This technique, less expensive than an open biopsy and with fewer complications, is best performed as part of a multidisciplinary approach with the surgeon's collaboration.

Adult↗
PubMed2006

Genetic and maternal determinants of effective dispersal: the effect of sire genotype and size at birth in side-blotched lizards.

We assessed genetic factors on progeny dispersal due to sire color morph genotypes in a field pedigree and lab crosses, and we measured maternal effects by studying both natural and experimentally induced egg size variation. Progeny were released into nature upon hatching, but we recorded dispersal distance at maturity, which reflects effective dispersal after viability selection has run its course. Progeny dispersal was significantly affected by sire genotype. Progeny from orange sires dispersed the farthest. Progeny from blue sires dispersed intermediate distances. Progeny from yellow sires were the most philopatric. Sire genotype effects interacted with egg size. In particular, enlarged progeny from orange sires dispersed farther, while enlarged progeny from yellow sires were more philopatric. Progeny from blue sires were unaffected by egg size manipulations. Egg manipulations and natural variation generally had concordant effects indicative of causation. However, asymmetry of gigantization and miniaturization on progeny dispersal from some sire genotypes suggest the involvement of maternal factors besides egg size. Results of laboratory crosses with progeny released into nature confirmed key sire genotype effects and identified additional maternal effects that modulated dispersal as a function of progeny gender. We discuss the adaptive implications of progeny dispersal in the context of male (rock-paper-scissors) and female strategies (r- and K-density cycle) that are associated with color morphs.

Animals↗
PubMed1998

Microevolution of a standard strain of Cryptococcus neoformans resulting in differences in virulence and other phenotypes.

Cryptococcus neoformans is a major fungal pathogen for patients with debilitated immune systems. However, no information is available on the stability of virulence or of phenotypes associated with virulence for C. neoformans laboratory strains. A serendipitous observation in our laboratory that one isolate of C. neoformans ATCC 24067 (strain 52D) became attenuated after continuous in vitro culture prompted us to perform a comparative study of nine strain 24067 isolates obtained from six different research laboratories. Each isolate was characterized by DNA typing, virulence for mice, proteinase production, extracellular protein synthesis, melanin synthesis, carbon assimilation pattern, antifungal drug susceptibility, colony morphology, growth rate, agglutination titers, phagocytosis by murine macrophages, capsule size, and capsular polysaccharide structure. All isolates had similar DNA typing patterns consistent with their assignment to the same strain, although minor chromosome size polymorphisms were observed in the electrophoretic karyotypes of two isolates. Several isolates had major differences in phenotypes that may be associated with virulence, including growth rate, capsule size, proteinase production, and melanization. These findings imply that C. neoformans is able to undergo rapid changes in vitro, probably as a result of adaptation to laboratory conditions, and suggest the need for careful attention to storage and maintenance conditions. In summary, our results indicate that C. neoformans (i) can become attenuated by in vitro culture and (ii) is capable of microevolution in vitro with the emergence of variants exhibiting new genotypic and phenotypic characteristics.

Agglutination Tests↗