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PubMed1993

Changing gravity level and the development of animals.

Space biology has accumulated a great body of information concerning the influence of microgravity upon objects of varying levels of biological organization: from microorganisms to higher animals and humans. However, the choice of biological objects was in most cases random, and there has been no attempt at a comparative biological analysis of the results obtained. A similar situation is noted in hypergravity research, where responses in various animal classes are compared mainly with respect to differences in body masses rather than in the level of biological organization. Without any claims to solve this serious problem in this presentation, I'll try to at least raise it, using as a starting point the conception about evolution of resistance and reactivity, created by my teacher N.N. Sirotinin (1981).

Acceleration↗
PubMed2002

A first formal link between the price equation and an optimization program.

The Darwin unification project is pursued. A meta-model encompassing an important class of population genetic models is formed by adding an abstract model of the number of successful gametes to the Price equation under uncertainty. A class of optimization programs are defined to represent the "individual-as-maximizing-agent analogy" in a general way. It is then shown that for each population genetic model there is a corresponding optimization program with which formal links can be established. These links provide a secure logical foundation for the commonplace biological principle that natural selection leads organisms to act as if maximizing their "fitness", provides a definition of "fitness", and clarifies the limitations of that principle. The situations covered do not include frequency dependence or social behaviour, but the approach is capable of extension.

Adaptation, Biological↗
PubMedDate not supplied

[Biological basis of fluoride resistance].

The authors synthetically illustrate some fundamental concepts about the mechanisms through which the oral flora develops fluoride resistance and the main consequences of this phenomenon at a biochemical and microbiological level. They briefly discuss the most recent experimental contributes of the literature in this field.

Adaptation, Biological↗
PubMed1997

Biology of plant cells in microgravity and under clinostating.

Experimental data on plant cell reproduction, growth, and differentiation in spaceflight and under clinostating that partially reproduce the biological effects of microgravity are elucidated. The rearrangements of organelle structural and functional organization in unicellular plant organisms as well as in meristematic, differentiating, and differentiated cells of multicellular organisms in these conditions are considered. The focus is on the changes in the interrelations of prokaryotic and eukaryotic organisms under altered gravity. Ideas on the acceleration of differentiation and aging of cells in microgravity and clinostating and the organism's adaptive possibilities for carrying out its own functions are discussed.

Adaptation, Biological↗
PubMed2005

The application of statistical physics to evolutionary biology.

A number of fundamental mathematical models of the evolutionary process exhibit dynamics that can be difficult to understand analytically. Here we show that a precise mathematical analogy can be drawn between certain evolutionary and thermodynamic systems, allowing application of the powerful machinery of statistical physics to analysis of a family of evolutionary models. Analytical results that follow directly from this approach include the steady-state distribution of fixed genotypes and the load in finite populations. The analogy with statistical physics also reveals that, contrary to a basic tenet of the nearly neutral theory of molecular evolution, the frequencies of adaptive and deleterious substitutions at steady state are equal. Finally, just as the free energy function quantitatively characterizes the balance between energy and entropy, a free fitness function provides an analytical expression for the balance between natural selection and stochastic drift.

Adaptation, Biological↗
PubMed1994

The two faces of growth: benefits and risks to bone integrity.

Bones grow by two processes: cortical bone is made by periosteal apposition (growth in width), and cancellous bone is made by endochondral ossification (growth in length). In both the axial and appendicular skeleton, about half of peak adult bone mass is accumulated during the adolescent growth spurt, which occurs two years earlier in girls than in boys, and is under pituitary control via interactions between growth hormone and sex hormones. Throughout growth, but particularly during adolescence, the ability of bone to adapt to mechanical loading is much greater than after maturity. This is the main reason why the effects of physical activity on bone are greater in cross-sectional studies in young athletes than in longitudinal studies in previously sedentary adults. In wild animals, by the time growth has ceased, the bones must be as strong as they will ever need to be, and attainment of further strength after cessation of growth would serve no biologic purpose. Adaptation of growing bone to mechanical loading is the purpose of the mechanostat, which enables physiologic adaptation in individuals to establish and maintain a species-specific property of the bones that is determined by evolutionary adaptation in populations. But growth confers risks as well as benefits to the skeleton. The large increase in incidence of upper extremity (particularly lower forearm) fractures, coincident with the adolescent growth spurt in both sexes, is due to an increase in cortical porosity as a consequence of an increase in intracortical bone turnover, which supplies some of the calcium needed by the growing ends of the long bones. This enables an increased demand for calcium to be spread over a longer time, analogous to the cyclic physiologic osteoporosis which occurs during the antler growth cycle in deer. The subsequent decline in cortical porosity is responsible for the continued increase in radial bone density after cessation of growth, referred to as consolidation. In the present state of knowledge, an increased incidence of fracture during the adolescent growth spurt is the inescapable consequence of an appropriate level of physical activity, and is the price that has to be paid in order to maximize bone accumulation during growth and minimize fracture risk in old age.

Adolescent↗
PubMed2006

Evolutionary paths underlying flower color variation in Antirrhinum.

To understand evolutionary paths connecting diverse biological forms, we defined a three-dimensional genotypic space separating two flower color morphs of Antirrhinum. A hybrid zone between morphs showed a steep cline specifically at genes controlling flower color differences, indicating that these loci are under selection. Antirrhinum species with diverse floral phenotypes formed a U-shaped cloud within the genotypic space. We propose that this cloud defines an evolutionary path that allows flower color to evolve while circumventing less-adaptive regions. Hybridization between morphs located in different arms of the U-shaped path yields low-fitness genotypes, accounting for the observed steep clines at hybrid zones.

Adaptation, Biological↗
PubMed2005

Compensatory adaptation to the loss of biological fitness associated with acquisition of fusidic acid resistance in Staphylococcus aureus.

Recent studies have shown that individual amino acid exchanges within elongation factor G (EF-G) cause fusidic acid resistance in Staphylococcus aureus. The data from the present study illustrate that the fusidic acid resistance-mediating amino acid substitutions P406L and H457Y are associated with a marked impairment of the biological fitness of S. aureus. In particular, strains producing EF-G derivatives with these mutations showed reduced growth, decreased plasma coagulase activity, and an impaired capability to compete with the isogenic wild-type strain. Second-site mutations within EF-G, such as A67T and S416F, that have been encountered in clinical fusidic acid-resistant isolates containing the amino acid exchanges P406L and H457Y, respectively, were shown not to contribute to resistance. Furthermore, the substitution A67T had no impact on the biological fitness in vitro. The exchange S416F, however, was found to function as a fitness-compensating mutation in S. aureus carrying the substitution H457Y in EF-G. In conclusion, the data presented in this report provide evidence at the molecular level that the deleterious effects of fusidic acid resistance-mediating exchanges within EF-G of S. aureus can be reduced considerably by specific compensating mutations in this target protein. This compensatory adaptation most likely plays a significant role in the stabilization of resistant bacteria within a given population.

Amino Acid Substitution↗
PubMed2002

The self-perceived survival ability and reproductive fitness (SPFit) theory of substance use disorders.

A new theory of substance use disorders is proposed-the SPFit theory-that is based on evolutionary biology and adaptive systems. Self-perceived survival ability and reproductive fitness (SPFit) is proposed as a human psychobiological construct that prioritizes and organizes (i.e. motivates) behavior, but is highly vulnerable to temporary, artificial activation by drugs of abuse. Autoshaping/sign-tracking/feature positive phenomena are proposed to underlie the development of craving and expectations about drugs as the individual learns that abused drugs will easily and reliably inflate SPFit. The cortico-mesolimbic dopamine system and its modulating interconnections are viewed as the biological substrate of SPFit; it is proposed to be a survival and reproductive motivation system rather than a reward center or reward pathway. Finally, the concept of modularity of mind is applied to the SPFit construct. Although considerable empirical data are consistent with the theory, new research is needed to test specific hypotheses derived from SPFit theory.

Biological Evolution↗
PubMed1975

Skin-piercing blood-sucking moths I: ecological and ethological studies on Calpe eustrigata (Lepid., noctuidae).

The Noctuid Calpe [Calyptral] eustrigata Hmps. was reported as a skin-piercing blood-sucking moth for the first time in Malaya (Bänziger, 1968) and is so far the only lepidopteran proved to suck blood by means of a piercing act. A few field observations and the description of the piercing behaviour of caged moths were given. Apart from a taxonomic study of the genus Calpe (Berio, 1956), a single record (Büttiker, 1969) and some notes on the moth's proboscis and possible evolutionary pathway (Bänziger, 1970, 1971, 1972) to our knowledge no other data have been published on the moth after its description as a new species (Hampson, 1926). The life cycle is completely unknown. From the scanty museum specimens available, it appears that the species inhabits South and Southeast Asia. A closely related, though less rare species, the fruit-piercing C. thalictri Bkh., has been used for a detailed study of the piercing mechanism likely to be adopted by Calpe (Bänziger, 1970); the feeding turned out to be as unusual as the feeding habits. Little or nothing is known about other Calpe species. C. eustrigata is not the only adult lepidopterous parasite of mammals. Lachryphagous ("eye-frequenting") moths feed as "marginal" parasites upon eye-secretions of ungulates, elephants and occasionally man (Shannon, 1928; Reid, 1954; Büttiker, 1964, 1967; Bänziger, 1966). Arcyophora species and the eulachryphagous Noctuid Lobocraspis graseifusa Hmps. which apparently feeds exclusively upon eye discharges, are suspected as vectors of eye diseases (Guilbride et al., 1959, Büttiker, 1964; Bänziger, 1972). While no lachryphagous moth is able to suck blood by a piercing act, there are a number of facultative lachryphagous moths which lick up the blood freely present at wounds, or that excreted anally by mosquitoes (Bänziger, 1969, 1972). Because of the scientific interest in C. eustrigata, research has been carried out to investigate different biological aspects of the species in Malaysia, Thailand. Laos and Indonesia (May 1971-May 1973). The first account presented here will be continued with a paper (in prep.) on the piercing mechanism and soon, it is hoped, with more information on the physiology, life cycle and medical importance of the moth.

Adaptation, Biological↗
PubMed1976

[The concept of health and disease].

1. The author reviews some current concepts concerning the definitions and uses of the concepts of health and illness. Starting from the definitions in Psychiatry, "normality" is considered from the statistic, the normative and the clinical standpoints, and as a part of a continuum stretching from health to illness. Several approaches are analyzed, among which Wittaker's, who sets forth the following indicators of normality: a) self-knowledge; b) self-esteem; c) self-security; d) capacity for giving and receiving affection; e) satisfaction of corporal needs; f) productivity and capacity for happiness; g) lack of tensions and of hipersensitivity. 2. The concept of illness as an operative concept is also analyzed, leading to the following statements: a) it is inexistent in non-biological sciences; b) it appears in social sciences only through extrapolation; c) in medicine it means the breacking of homeosthasis; d) in psychology and dynamic psychiatry it means the abnormal stressing of normal mechanisms, common to all persons. 3. The concept of health as equilibrium is also analyzed, with the following precisions: a) equilibrium is defined within a system as affecting the whole of it, and implying transformation and self-regulation; b) homeosthasis is a case of equilibrium for steady complex systems; c) adaptation is the maintenance of equilibrium when there are exchanges with the evironment. 4. Finally, those concepts are applied to mental illness and its limits, and the following criteria are set forth: a) amount of anguish; b) depression related to its motives, intensity, persistence and frequency; c) regression to previous development stages; d) use of defense mechanisms in an inadequate or stereotyped way.

Adaptation, Biological↗
PubMed2004

Maternal programming of individual differences in defensive responses in the rat.

This paper describes the results of a series of studies showing that variations in mother-pup interactions program the development of individual differences in behavioral and endocrine stress responses in the rat. These effects are associated with altered expression of genes in brain regions, such as the amygdala, hippocampus, and hypothalamus, that regulate the expression of stress responses. Studies from evolutionary biology suggest that such "maternal effects" are common and often associated with variations in the quality of the maternal environment. Together these findings suggest an epigenetic process whereby the experience of the mother alters the nature of the parent-offspring interactions and thus the phenotype of the offspring.

Adaptation, Biological↗
PubMed2006

A maternal-offspring coadaptation theory for the evolution of genomic imprinting.

Imprinted genes are expressed either from the maternally or paternally inherited copy only, and they play a key role in regulating complex biological processes, including offspring development and mother-offspring interactions. There are several competing theories attempting to explain the evolutionary origin of this monoallelic pattern of gene expression, but a prevailing view has emerged that holds that genomic imprinting is a consequence of conflict between maternal and paternal gene copies over maternal investment. However, many imprinting patterns and the apparent overabundance of maternally expressed genes remain unexplained and may be incompatible with current theory. Here we demonstrate that sole expression of maternal gene copies is favored by natural selection because it increases the adaptive integration of offspring and maternal genomes, leading to higher offspring fitness. This novel coadaptation theory for the evolution of genomic imprinting is consistent with results of recent studies on epigenetic effects, and it provides a testable hypothesis for the origin of previously unexplained major imprinting patterns across different taxa. In conjunction with existing hypotheses, our results suggest that imprinting may have evolved due to different selective pressures at different loci.

Adaptation, Biological↗
PubMed2006

Natural selection and population dynamics.

To what extent, and under which circumstances, are population dynamics influenced by concurrent natural selection? Density dependence and environmental stochasticity are generally expected to subsume any selective modulation of population growth rate, but theoretical considerations point to conditions under which selection can have an appreciable impact on population dynamics. By contrast, empirical research has barely scratched the surface of this fundamental question in population biology. Here, we present a diverse body of mostly empirical evidence that demonstrates how selection can influence population dynamics, including studies of small populations, metapopulations, cyclical populations and host-pathogen interactions. We also discuss the utility, in this context, of inferences from molecular genetic data, placing them within the broader framework of quantitative genetics and life-history evolution.

Adaptation, Biological↗
PubMed2003

Effect of steroids on intestinal lipid uptake in rats is enhanced by a saturated fatty acid diet. Cell and molecular biology collaborative network in gastrointestinal physiology.

Glucocorticosteroids enhance sugar digestive and absorptive functions of the intestine, but their effect on lipid uptake is unknown. Modifications in dietary lipids alter the nutrient transport properties of the intestine. The influence of 4 weeks' treatment with budesonide (BUD), prednisone (PRED), or control vehicle in weanling rats fed either an isocaloric semisynthetic saturated fatty acid diet (SFA) or a polyunsaturated fatty acid diet (PUFA), on the uptake of lipids was assessed using everted gut rings. PRED and BUD increased the uptake of several fatty acids, and this was higher when the animals were fed SFA rather than PUFA. Changes in expression of the mRNAs for L-FABP (liver fatty acid binding protein) and ILBP (ileal lipid binding protein) did not explain these alterations in lipid uptake. Dietary lipid signalling of this adaptive response may involve proglucagon, c-jun, TNF-alpha and IL-10, whereas steroid signalling may involve proglucagon. In summary, steroids increase the absorption of lipids by a process which can be enhanced by the substitution of saturated for polyunsaturated lipids in the diet, and which is not explained by alterations in the expression of the mRNAs of L-FABP or ILBP.

Adaptation, Biological↗
PubMed2004

Differential correlates of diet and phylogeny on the shape of the premaxilla and anterior tooth in sparid fishes (Perciformes: Sparidae).

We explore the correlational patterns of diet and phylogeny on the shape of the premaxilla and anterior tooth in sparid fishes (Perciformes: Sparidae) from the western Mediterranean Sea. The premaxilla is less variable, and in spite of the presence of species-specific features, a common structural pattern is easily recognizable in all species (i.e. the ascending and the articular processes are fused in a single branch, as in many percoid fishes). In contrast, tooth shape is more variable, and different structural types can be recognized (e.g. canine-like or incisive). Coupling geometric morphometric and comparative methods we found that the relationship between shape, diet and phylogeny also differs between premaxilla and tooth. Thus, the shape of the premaxilla is significantly correlated with food type, whereas the shape of the teeth is not correlated with diet, and probably reflects the species phylogenetic relationships. Two biological roles, resistance against compressive forces generated in the buccal cavity and the size of the oral gape, would explain the ecomorphological patterns of the premaxilla. The premaxilla and anterior tooth appear to evolve at different rates (mosaic evolution) and represent an example of morphological traits belonging to the same functional unit but following uncoupled evolutionary pathways.

Adaptation, Biological↗
PubMed1991

HIV-1: seven facets of functional molecular mimicry.

Molecular mimicry, where structural properties borne by a pathogen "imitate" or "simulate" molecules of the host, is shown to take make different forms in the molecular biology of the human immunodeficiency virus type 1 (HIV-1). There is considerable evidence that a number of important immunopathologic processes are incited by HIV-1 infection, due to molecular mimicry. Accordingly, a systematic review of this evidence is intended to define the fundamental immunopathogenic properties of this virus in terms relevant to the science of acquired immunodeficiency syndrome (AIDS) susceptibility, prevention, and treatment.

Adaptation, Biological↗