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PubMed1987

Point mutations as an optimal search process in biological evolution.

Point mutations are pictured as jumps in a phase space representing the sequences of amino acids or nucleotides as discrete points. It is shown that this space can be given a natural metric by quantifying common physical and chemical properties of amino acid constituents in terms of a natural measure. Evolution through point mutations is simulated by the search for points in the phase space representing amino acid sequences of high survival fitness. Due to the local compactness of the distribution of these functionally allowed points in phase space any successful search procedure has characteristics qualitatively different from those in the case of a random distribution. This is demonstrated by model calculations. A specified distribution of allowed points is generated with subsequent evaluation of the success of the retrieval process as a function of the jump probabilities between lattice sites. The results of such simulations are compared with data obtained from the analysis of the DNA or mRNA sequences coding related proteins. By counting silent and expressed nucleotide replacement frequencies one can draw conclusions as to the efficacy of the natural evolutionary search processes in the phase space of amino acid sequences. There are cases, where the highest possible information gain of one bit per accepted point mutation is achieved. In general the information gain is found to be somewhat sub-maximal due to functional requirements.

Amino Acid Sequence↗
PubMedDate not supplied

Relationship between specialized cells, capillaries and intermediary cytofibrillary elements. XIth note. Biological evolution of the emunctory subsystem and stereotype in vertebrates.

This note completes in vertebrates the study of the emunctory subsystem and stereotype in invertebrates (Xth note). The theory of systems (and of open biological systems) of Bertalanffy, the theory of internal laws and limits of each organizational level (Needham) and the theory of biological stereotypes and of their morphofunctional expression (Mârza, Repciuc and Eskenasy) are also corroborated. In this light there were studied: the characters of the emunctory stereotype in vertebrates, its similar formation mode by three links (extracting, conveying and excretory links) as in the coelomatous invertebrates, and the passage of the emunctory stereotype from invertebrates to vertebrates. The present-day Acraniata and their offsprings, the Protocraniata, Agnatha and aquatic Gnathostoma, have an emunctory stereotype identical in its essential characters, without discrepancies between its links. The passage does not occur, however, from the metanephridia to the pronephros, but to the mesonephros. This latter reaches its highest functional limits in Dipnoi and Amphibia. The author indicates the mechanisms which, in its opinion, play a role in the activation of organo-genetic capacities of the metanephros in the caudal nephrogenic area. The importance of the three nephrogenic areas of the vertebrates, their succession and interdependence are also discussed. The problem of the archi(holo)nephros is critically reviewed, and the author's hypothesis that the glomerular ultrafiltrate and the coelomic liquid of invertebrates with metanephridia had the same composition and underwent the same processes of reabsorption-secretion is dwelt upon. A conclusion is drawn from these two notes, according to which stability--directed by the stabilizing selection--plays a directional role in the evolution of the new organizational levels, in the maintenance and development of the characters of the emunctory stereotype within the emunctory subsystem (EMSS). Between variability and stability strong relations are established and hereditarily transmitted.

Adaptation, Biological↗
PubMedDate not supplied

Relationships between specialized cells, capillaries and intermediary cytofibrillary elements. XVth note. Biological evolution of the respiratory stereotype and subsystem in aquatic vertebrates.

The author continues in aquatic vertebrates the study of the evolution of the respiratory stereotype initiated in the XIIth note of this series and carried out in the light of the systemic conception (Bertalanffy), of Needham's theory of order in nature, and of the theory of biological stereotypes (Mârza, Repciuc, Eskenasy). The stability of some characters of the respiratory stereotype inherited by vertebrates from invertebrates is pointed out. The respiratory stereotype in vertebrates gradually passed from the respiration of water-dissolved oxygen through branchiae and skin, to the concomitant uptake of this form and of air oxygen (through buccopharyngeal formations, gaseous bladder or rudimentary lungs in osseous fishes), the double respiration (in Amphibia) and later the air respiration in Reptilia. The five steps of this gradual evolution are described, as well as the conditions of the evolution from crossopterygians to Tetrapoda (amphibians and reptiles).

Air↗
PubMed1997

Major "anastrophes" in the origin and early evolution of biological energy conversion.

The metabolism of living organisms has long been usefully divided into anabolism and catabolism. Anabolism is constructive, being concerned with the assembly of complex molecules, whereas catabolism is destructive in the sense that it involves the degradation of molecules. In addition to the well-known word catastrophe for sudden, drastic destruction and its consequences, it has been found practical to introduce in the evolutionary context the word "anastrophe" (an old greek word for turning back, in the opposite direction-from anastrephein, where ana = back and strephein = to turn) to cover sudden, drastic constructive events and their consequences. Mutations in genes and genomes giving selective advantage to an organism are typical anastrophic events. A single site mutation in a gene coding for a protein may be good, neutral or bad, or anastrophic, neutral or catastrophic, respectively, for the organism. The consequence of an anastrophic mutation may be a decisive first step on the long way to a new species, whereas a catastrophic mutation may lead to major cell damage or death. This example of the use of the anastrophe concept in biological evolution leads to the question about its applicability to other parts and paths of the cosmic evolutionary process, such as physical, chemical, social and cultural evolution. Here it will be mainly considered in connection with the energy conversion aspects of the chemical evolution leading to the origin of life and of the subsequent early biological evolution. More specifically, it will be attempted to describe possible major anastrophes in energy conversion both before and after the first occurrence of life on earth.

Animals↗
PubMed2003

Spherule beds 3.47-3.24 billion years old in the Barberton Greenstone Belt, South Africa: a record of large meteorite impacts and their influence on early crustal and biological evolution.

Four layers, S1-S4, containing sand-sized spherical particles formed as a result of large meteorite impacts, occur in 3.47-3.24 Ga rocks of the Barberton Greenstone Belt, South Africa. Ir levels in S3 and S4 locally equal or exceed chondritic values but in other sections are at or only slightly above background. Most spherules are inferred to have formed by condensation of impact-produced rock vapor clouds, although some may represent ballistically ejected liquid droplets. Extreme Ir abundances and heterogeneity may reflect element fractionation during spherule formation, hydraulic fractionation during deposition, and/or diagenetic and metasomatic processes. Deposition of S1, S2, and S3 was widely influenced by waves and/or currents interpreted to represent impact-generated tsunamis, and S1 and S2 show multiple graded layers indicating the passage of two or more wave trains. These tsunamis may have promoted mixing within a globally stratified ocean, enriching surface waters in nutrients for biological communities. S2 and S3 mark the transition from the 300-million-year-long Onverwacht stage of predominantly basaltic and komatiitic volcanism to the late orogenic stage of greenstone belt evolution, suggesting that regional and possibly global tectonic reorganization resulted from these large impacts. These beds provide the oldest known direct record of terrestrial impacts and an opportunity to explore their influence on early life, crust, ocean, and atmosphere. The apparent presence of impact clusters at 3.26-3.24 Ga and approximately 2.65-2.5 Ga suggests either spikes in impact rates during the Archean or that the entire Archean was characterized by terrestrial impact rates above those currently estimated from the lunar cratering record.

Astronomy↗
PubMed2002

Thermodynamics of biological evolution and aging. Supramolecular thermodynamics is a key to understanding phenomena of life. What is life from a physical chemist's viewpoint.

The law of temporal hierarchies of the biological world allows us to pick out of the biomass quasi-closed thermodynamic systems with a given hierarchy. It has been established, that the use of this law of Nature as applied to supramolecular structures of organisms allows us the opportunity of using the methods of equilibrium supramolecular thermodynamics in the examination of open living systems. It has been shown that supramolecular thermodynamics is one of the "keys", which allows us to explain the origin of life and evolution of living beings. The second law of thermodynamics in its classic formulation (R. Clausius, J.W. Gibbs) is easy to apply in order to make calculations, carried out through methods of chemical, supramolecular and overall hierarchical thermodynamics.

Aging↗
PubMed2006

[Biological evolution and ancient DNA].

Twenty years after the advent of ancient DNA studies, this discipline seems to have reached the maturity formerly lacking to the fulfilment of its objectives. In its early development paleogenetics, as it is now acknowledged, had to cope with very limited data due to the technical limitations of molecular biology. It led to phylogenetic assumptions often limited in their scope and sometimes non-focused or even spurious results that cast the reluctance of the scientific community. This time seems now over and huge amounts of sequences have become available which overcome the former limitations and bridge the gap between paleogenetics, genomics and population biology. The recent studies over the charismatic woolly mammoth (independent sequencing of the whole mitochondrial genome and of millions of base pairs of the nuclear genome) exemplify the growing accuracy of ancient DNA studies thanks to new molecular approaches. From the earliest publications up to now, the number of mammoth nucleotides was multiplied by 100,000. Likewise, populational approaches of ice-age taxa provide new historical scenarios about the diversification and extinction of the Pleistocene megafauna on the one hand, and about the processes of domestication of animal and vegetal species by Man on the other. They also shed light on the differential structure of molecular diversity between short-term populational research (below 2 My) and long-term (over 2 My) phylogenetic approaches. All those results confirm the growing importance of paleogenetics among the evolutionary biology disciplines.

Animals↗
PubMed2005

Hantaviruses: molecular biology, evolution and pathogenesis.

Hantaviruses are tri-segmented negative sense single stranded RNA viruses that belong to the family Bunyaviridae. In nature, hantaviruses are exclusively maintained in the populations of their specific rodent hosts. In their natural host species, hantaviruses usually develop a persistent infection with prolonged virus shedding in excreta. Humans become infected by inhaling virus contaminated aerosol. Unlike asymptomatic infection in rodents, hantaviruses cause two acute febrile diseases in humans: hemorrhagic fever with renal syndrome (HFRS) and hantavirus pulmonary syndrome (HPS). The mortality rate varies from 0.1% to 40% depending on the virus involved. Hantaviruses are distributed world wide, with over 150,000 HFRS and HPS cases being registered annually. In this review we summarize current knowledge on hantavirus molecular biology, epidemiology, genetic diversity and co-evolution with rodent hosts. In addition, special attention was given in this review to describing clinical manifestation of HFRS and HPS, and advances in our current understanding of the host immune response, treatment, and prevention.

Animals↗
PubMedDate not supplied

Relationships between specialized cells, capillaries and intermediary cytofibrillary elements. XIIth note. Biological evolution of the respiratory stereotype and subsystem in invertebrates.

This note presents the respiratory stereotype and subsystem in invertebrates, developing the previous notes on the emunctory stereotype and subsystem (Xth and XIth notes). As in the previous ones, Cannon's homeostasis conception and Bertlanffy's theory of systems were corroborated with Needham's theory of internal laws and of limits of organizational biological levels, and with the author's theory of biological stereotypes (Mârza, Repciuc, Eskenasy, 1962). Four links of the respiratory stereotype (Rsp. Stp.) and subsystem (Rsp. SS) were distinguished. The respiratory subsystem was differentiated when, in triblastic animals, the organizational level of higher worms and of their offsprings was reached. The four links of the Rsp. Stp. are: the Ist link is represented by the oxidoreduction processes of tissue and organ cells; the IInd is the internal conveying link of O2 and CO2; the IIIrd comprises the osmotic surfaces changes and the transport of gases inwards the branchiae or lungs, and later by the water (respectively air)--blood barrier; the IVth link is formed from the structures and mechanisms of rhythmic movements which significantly increase the exchanges at the barrier level. Each link has its specific properties. The gradual evolution of each link and of the vicarious organs of gas exchange is dwelt upon, as well as the interactions between the respiratory subsystem and the other homeostasis subsystems. The theoretical interpretation of the Rsp. Stp. and Rsp. SS evolution also resorted to the theories of stabilizing selection (Schmalhausen, 1949), of canalizing selection (Waddington, 1975 and of disruptive selection (Simpson, 1953; Mayr, 1970).

Animals↗
PubMed2001

Histological and biological evolution of human premalignant breast disease.

Most human invasive breast cancers (IBCs) appear to develop over long periods of time from certain pre-existing benign lesions. Of the many types of benign lesions in the human breast, only a few appear to have significant premalignant potential. The best characterized of these include atypical hyperplasias and in situ carcinomas and both categories are probably well on along the evolutionary pathway to IBC. Very little is known about earlier premalignant alterations. All types of premalignant breast lesions are relatively common but only a small proportion appear to progress to IBC. They are currently defined by their histological features and their prognosis is imprecisely estimated from indirect epidemiological evidence. Although lesions within specific categories look alike, they must possess underlying biological differences causing some to remain stable and others to progress. Recent studies suggest that they evolve by highly diverse genetic mechanisms and research into these altered pathways may identify specific early defects that can be targeted to prevent premalignant lesions from developing or becoming cancerous. It is far more rational to think that breast cancer can be prevented than cured once it has developed fully. This review discusses histological models of human premalignant breast disease that provide the framework for scientific investigations into the biological alterations behind them and examples of specific biological alterations that appear to be particularly important.

Breast↗
PubMed2000

Conservation of the basic pattern of cellular amino acid composition during biological evolution in plants.

The cellular amino acid composition of plant cells was analyzed. The callus of carrot (Daucus carota), leaves of Torenia fournieri and protocomb-like body of Cymbidium, s.p. were examined as examples of plant cells. The cellular amino acid compositions differed in the plant cells, but their basic patterns were quite similar. It is concluded that the basic pattern of the cellular amino acid composition is conserved in all terrestrial organisms, including plants.

Amino Acids↗
PubMed1984

Chemical and biological evolution in space.

Astronomical infrared spectra are used to confirm the existence of complex organic molecules produced by ultraviolet photoprocessing of interstellar grain mantles. This material is shown to be the major component of the interstellar grains between the sun and the galactic center and, by inference, constitutes more than 10 million solar masses--or close to one part in a thousand of the entire mass of the milky way galaxy. It may be demonstrated that the primitive chemistry of the earth's surface was dominated by these extraterrestrial molecules after aggregated into comets if the rate of comet impacts with the earth was comparable with that required to account for the extinction of species over the past 300 million years. Ultraviolet irradiation of bacterial spores has been studied for the first time under simulated interstellar conditions. The inactivation time predicted for the less dense regions of space is at most several hundred years. Within molecular clouds it is shown on theoretical and experimental grounds that this time may be extended to tens of million of years which is the estimated time required for their transport from one solar system to another by a molecular cloud. However survival of spores during their initial exposure to the solar ultraviolet presents a problem for panspermia because it requires that in the process of ejection from the earth's surface they must be enclosed within a cocoon (or mantle) of ultraviolet absorbing material of approximately 0.6 micrometer thickness. Thus, although panspermia can not be rejected on the basis of lack of interstellar survival there may remain insurmountable obstacles to its occurring because of the very special protective shield requirements during ejection from its planetary source.

Bacillus subtilis↗
PubMed2003

Molecular strategies in biological evolution of antimicrobial peptides.

Gene-encoded antimicrobial peptides that protect the skin of hylid and ranin frogs against noxious microorganisms are processed from a unique family of precursor polypeptides with a unique pattern of conserved and variable regions opposite to that of conventional secreted peptides. Precursors belonging to this family, designated the preprodermaseptin, have a common N-terminal preproregion that is remarkably well conserved both within and between species, but a hypervariable C-terminal domain corresponding to antimicrobial peptides with very different lengths, sequences, charges and antimicrobial spectra. Each frog species has its own distinct panoply of 10-20 antimicrobial peptides so that the 5000 species of ranids and hylids may produce approximately 100,000 different peptide antibiotics. The strategy that these frogs have evolved to generate this enormous array of peptides includes repeated duplications of a 150 million years old ancestral gene, focal hypermutation of the antimicrobial peptide domain maybe involving a mutagenic DNA polymerase similar to Escherichia coli Pol V, and subsequent actions of positive (diversifying) selection. The hyperdivergence of skin antimicrobial peptides can be viewed as the successful evolution of a multi-drug defense system that provides frogs with maximum protection against rapidly changing microbial biota and minimizes the chance of microorganisms developing resistance to individual peptides. The impressive variations in the expression of frog skin antimicrobial peptides may be exploited for discovering new molecules and structural motifs targeting specific microorganisms for which the therapeutic armamentarium is scarce.

Amino Acid Sequence↗
PubMed1994

Effect of gamma-interferon on the clinical and biologic evolution of hypertrophic scars and Dupuytren's disease: an open pilot study.

Hypertrophic scars and Dupuytren's disease are characterized by the presence of modified fibroblasts or myofibroblasts which are allegedly responsible for tissue retraction and excessive connective tissue production. gamma-Interferon, a cytokine produced by T-helper lymphocytes, has been shown to decrease fibroblast replication, alpha-smooth-muscle actin (the actin isoform characterizing myofibroblasts) expression, and collagen production. We have investigated in an open pilot study the possibility that intralesional injections of gamma-interferon exert a beneficial effect on the evolution of hypertrophic scars and Dupuytren's disease. In the 14 selected patients, gamma-interferon decreased the symptoms and the size of the lesions of both diseases; in hypertrophic scars, immunofluorescence examination showed that alpha-smooth-muscle actin expression also was decreased in myofibroblasts. Moreover, in fibroblasts cultured from 4 patients with hypertrophic scars, gamma-interferon decreased replication and alpha-smooth-muscle actin expression in vitro. Our results suggest that gamma-interferon could represent a useful adjunct to the nonsurgical therapy of hypertrophic scars and Dupuytren's disease. Larger controlled clinical studies, however, should test the validity of these preliminary observations.

Actins↗