Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Evolutionary”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,603 records · Page 89Linked to original sources
PubMed1989

An evolutionary link for developing mammalian lungs.

Lungs of the human infant and those of other mammals are filled with fluid immediately prior to birth. Studies of the ionic composition of this fluid indicate that active ionic transport processes occur in the epithelial cells of the potential airspaces. The purpose of this study was to see if these active ion pumps were present in developing species other than mammals thus providing a possible evolutionary link to mammals. A series of samples of lung liquid, amniotic fluid, and plasma were taken from embryonic marine turtles gathered from clutches incubating in the beach at Mon Repos, Queensland, Australia during the summer of 1986-87. The concentrations of sodium, potassium and chloride ions and protein measured in these liquids indicated that active pumping processes similar to that seen in the mammalian lung were present in the developing lungs of these marine reptiles and further, circumstantial evidence was gathered to suggest that this liquid was partially reabsorbed prior to hatching. The results support the notion that processes responsible for the normal development of the human lung and lungs of other mammals are also present in the hollow lungs of marine turtles. Thus there is an evolutionary counterpart controlling lung development in more ancient species. It may be possible to generalize this observation to the development of hollow lungs of other species.

Animals↗
PubMed1989

Rapid evolutionary repair of base mispairings in stem regions of eukaryotic 5S rRNA.

An extensive set of 216 eukaryotic 5S rRNA sequences are compared and the previous observations, that (i) invariable base positions are located primarily in loop regions and (ii) stem regions are more variable but the number of mispairings is kept small, are confirmed. On the basis of a comparison of the contemporary sequences, evolutionary processes of base substitutions in stem regions are discussed. It is found that there is no evident selective pressure to keep a particular kind of base pair in stem regions and individual bases may change freely as long as mispairings are kept few. It is also found that the secondary structure of 5S rRNA has been maintained stable by an equilibrium between base pair formation- and destruction-substitutions and that the low occurrence of mispairings in stem regions is attributable to a high value (ca. 90) of the equilibrium constant. The present analyses suggest a structure-function relationship of the eukaryotic 5S rRNA; stem regions structurally help loop regions to interact well with other ribosomal components and therefore, there is a marked selection pressure to maintain the secondary structure under the evolutionary noise of mutation.

Animals↗
PubMed1988

Ultrastructural peculiarities of the supraoptic nucleus of Mauremys caspica (turtle): its evolutionary interest in reptiles.

The hypothalamic Supraoptic Nucleus (SON) supposes an evolutionary achievement in the reptiles, zoological group in which this nucleus is first differentiated. Its scarce development in the chelonian, subject of the present study, is related to their primitive brain pattern. The peculiar location and the topographical configuration of the SON in the hypothalamus of the turtle Mauremys caspica allows to evidence morphologically the successive steps in the evolutionary process from lower to higher vertebrates. The marked neurosecretory character of the chelonian SON is the unequivocal proof of its philogenetic origin derived from the magnocellular preoptic nucleus of lower vertebrates.

Animals↗
PubMed1988

The evolutionary role of research.

Every evolutionary process consists in the stochastic occurrence of quasi-random transitions from a given ordered system, with some criteria of stability ensuring that a few of the modified system survive, forming new ordered system that can serve as departure points for a further evolutionary step. In the evolution of human societies, scientific research fulfills the role of the quasi-random mutations.

Biological Evolution↗
PubMed1987

Evolutionary aspects of reptilian and mammalian enamel structure.

The evolution of enamel structure is dealt with here on the basis of fossil reptiles and mammals ranging from the Triassic to the present. The evidence suggests that prismatic enamel had developed in some therapsid reptiles and the mammal, Eozostrodon about 180 million years ago. For the next 100 million years, mammalian evolutionary history is sparingly documented and this is reflected in the poor record of enamel evolution during this period. The few Jurassic reptiles and mammals studied suggest a preprismatic structure. In the Late Cretaceous (80 to 65 million years ago) when the fossil record improves, mammalian enamel investigated from North American localities, are found to be prismatic; allotherian (multituberculate) and metatherian (marsupial) enamels are usually tubular, while eutherian (placental) ones are not. Prism structure in Tertiary mammals in general, conforms to that of their present day descendants, but there are discernible exceptions. The record of evolutionary change in Tertiary mammals is obscured by functional modifications related to biomechanical stresses. Enamel structure may be secondarily modified; similar in phylogenetically unrelated groups (eg., pauciserial enamel of early rodents) or dissimilar at the intra-familial level (eg., rodent families Ctenodactylidae and Ischryomyicae). Prismatic enamel is recorded from the tooth of a hatchling of the gavial, Gavialis gangeticus.

Animals↗
PubMed1987

[The angular process of Monodelphis domestica (Didelphidae, Marsupialia) and its relation to the middle ear: an ontogenetic and evolutionary morphologic study].

In most marsupials, the angular process is inflected medially. By using an ontogenetic series of Monodelphis domestica, the development of this characteristic structure has been described. In contrast with the eutherian mammals, in marsupials there is retained a close connection between the dentale and the tympanicum and goniale; it is well known that these 2 elements of the middle ear are derived from the angulare and prearticulare of the reptilian lower jaw. At the neonatal stage, the dentale and tympanicum are both relatively vertically orientated; during the following 2 weeks, they take an increasingly oblique position, which is primarily caused by the rapid growth of the braincase. Only after the eruption of the first teeth, the ascending ramus of the dentale takes a more and more vertical position, whereas the angular process remains with its tip near the medioventral floor of the tympanic bulla. The bulla shows at this place a rectangular fenestra which is covered by a membrane of loose connective tissue; the tip of the angular process, which is always free of muscular insertions, maintains contacts with this fenestra throughout life. During juvenile and adult life stages, the process becomes somewhat removed from the fenestra for obvious reasons, but at a gape of about 40 to 50 degrees it inevitably must touch the "inferior tympanic membrane" and possibly also the tympanic ring. It is speculated that the relationship between the angular process and the tympanic bulla represents a specific form-function complex for sound transmission, which may be a modified retention from archaic mammalian conditions. Further details of the ontogenetic development of the tympanic region have been described which may be of some relevance for the evolutionary morphology of mammals: The tympanic process of the petrosal, which fixes the posterior end of the tympanic ring, is formed by 'Zuwachsknochen' (additional bone) but not by cartilage. The styloid process remains cartilaginous throughout life: its free tip ends in the lateral wall of the tympanic cavity and it is closely connected with the collum mallei and the posterior end of the tympanicum; it guides the chorda tympani and may therefore be homologous with the cartilage of Spence. The cartilage of Paauw is interpreted in terms of functional morphology. A model of evolutionary transformation of the dentale-tympanicum complex in mesozoic mammals in outlined on the basis of the ontogenetic findings in Monodelphis and other didelphid and dasyurid marsupials.

Aging↗
PubMed1986

[Upright posture of the human and the morphologic evolution of the musculi extensores digitorum pedis with reference to evolutionary myology].

A brief literature review is made of the morphological changes in the bones of the lower limbs of man, which are the result of his upright walk. The author's task has been to study the morphological changes of Mm. extensores digitorum pedis from the viewpoint of evolutionary myology. The following material has been studied: Lower limbs of adults, 151 less than or equal to N less than or equal to 358. Pelvic limbs of Marsupialia, Insectivora, and non-hominide primates; N = 122. Lower limbs of human embryos and fetuses; N = 71. The following acknowledgements are the author's own studies. They begin with an evolutionary-myological study of m. extensor hallucis longus and of m. extensor digitorum longus, together with m. peroneus tertius.

Biological Evolution↗
PubMed1979

Evolutionary relationships of the gut hormones.

Peptides identical or related to mammalian gut hormones occur widely, not just in gut endocrine cells but also in central or peripheral nerves, amphibian skin glands, and a variety of invertebrate tissues. The dual distribution in brain and gut was probably already established early in the vertebrate line; representatives of the oldest vertebrate group, the cyclostomes, have cholecystokinin-like factors in gut endocrine cells and in brain. The related sequences of certain gut peptides, notably gastrin and cholecystokinin (CCK), and secretin, glucagon, vasoactive intestinal polypeptide (VIP), and gastric inhibitory peptide (GIP), indicate evolution from common ancestral molecules by gene duplication and divergence. Functionally important residues are conserved. Thus the COOH-terminal pentapeptide common to gastrin and CCK also contains their minimal active fragment. There are also evolutionary changes at the level of the target organ receptor mechanisms: these are also evolutionary changes at the level of the target organ receptor mechanisms; these are illustrated by evidence suggesting that secretin regulates the flow of pancreatic juice in mammals whereas the structurally related peptide VIP has a similar role in birds.

Animals↗
PubMedDate not supplied

[Evolutionary aspects of the distribution of Ascaridoidea in mammals (author's transl)].

In an attempt to interpret the distribution of Ascaridoidea in Mammals and Birds, a scheme is proposed, based on the concept of geological periods of evolutionary expansion for parasitic lines. It is assumed that the evolutionary expansion period of Ascaridoidea in Mammals occurred after the diversification of primitive mammals; this would explain the absence of ascarids in these groups. Periods of evolution appear to coincide with the diversification of Carnivora and Sirenia, the first to become invaded; Artiodactyla and Equidae became invaded later, at the time of their diversification. The other cases of parasitism of Mammals by Ascarids are thought to be "captures".

Animals↗
PubMed1977

[Evolutionary myology as a research method in the morphological evolution of human muscles].

The author presents the evolutionary myology as a complex research method by which the morphological transformation of human muscles could be proved. This process of muscle transformation is elucidated by 3 investigation types: 1. Morphological macroscopic investigation of the variations of certain human muscle. 2. Comparative anatomic investigation of the same muscle. 3. Muscle organogenetic study of human embryos and fetuses. The macroscopic morphological investigation of the variations of any human muscle enables the examination of the variability in its complete versatility and volume if a sufficient number of preparations are investigated. A line of successive muscle variations could be composed from the established variants, arranged one after another. Furthermore, the frequency of each variation could be determined in per cents. The material for comparative-anatomic investigation must be selected according to the contemporary zoology. The variation line of human material can be properly directed due to that examination. Now it is possible to understand which is the initial form, the transitional forms and the final form of the transformation process. Thus the direction of transformation process could be understand. The muscle organogenetic investigation must be carried out on human embryos and fetuses of different ages. In this way muscle and tendion primordium could be observed directly and in the same time the important factors about the primordium maturity and its eventual shifting could be established. The example described refers to the transformation of m. abductor pollicis longus. It reveals how the evolutionary myology can be used to prove the morphological evolution of any muscle.

Female↗
PubMed1995

Multichannel PCR and serial transfer machine as a future tool in evolutionary biotechnology.

As an improved strategy for producing functional macromolecules by in vitro evolutionary optimization, we propose an automated machine that can process up to 960 samples in parallel. It consists of a 960-well PCR machine with special sealed plastic reaction vessels and appropriate handling devices. We show that the heat-sealing technique does not significantly affect the activity of Taq DNA Polymerase or that of the temperature-sensitive Q beta RNA polymerase but avoids cross-contamination and evaporation of the samples. Initial experiments demonstrate the suitability of the apparatus to uniformly process the samples and to perform the thermocycling. Serial transfer of reaction products into fresh reaction solution was used to initiate further rounds of amplification as a typical experimental setup for an evolutionary biotechnology application.

Allolevivirus↗
PubMed1976

[Several methodologic problems of evolutionary histology in light of the findings of molecular genetics].

The paper elucidates certain methodological problems of evolutionary histology. The principal attention is given to the necessary synthesis of modern molecular biology and genetics and evolutionary histology. Modern data on the levels of the organization of the living matter and their significance for the rightness of the A.A. Zavarzin's theory of parallel lines in the tissue evolution are presented. The hypothesis of an application of the theory of parallel lines in the hereditary variability by N.I. Vavilov to the analysis of regularities of the tissue evolution is set forth. The hypothesis is proposed that mutation changes of similar genes in representatives of different types of animals underlie the regularities of the tissue evolution discovered by A.A. Zavarzin, and epigenomic changes of regulation systems occurring most frequently in the process of ontogenesis of organisms lie in the basis of the divergent evolution of tissues after N.G. Chlopin.

Biological Evolution↗
PubMed1994

The morphological basis of self-organization. Developmental and evolutionary aspects.

Developmental self-organization is usually considered as a matter of reaction-diffusion systems. These systems, however, require a specification that can arise only from natural selection. Meanwhile, in the evolutionary context, self-organization is equivalent to the origination of evolutionary novelties: this implies that new structural patterns emerge before they acquire a definite biological function, so that selection is of no relevance in this case. It follows that self-organization should be inherent to the macroscopic (morphological) level of the developing system. Our idea is that the morphogenetic process can emerge on the macroscopic scale only provided that the temporal sequence of events is realized as a spatial sequence of morphological states, and vice versa.

Animals↗
PubMed1994

An Ig heavy chain enhancer of the channel catfish Ictalurus punctatus: evolutionary conservation of function but not structure.

The teleost fishes are among the earliest evolutionary lineages to have an Ig heavy chain (IgH) locus whose organization approximates that of mammals. To understand transcriptional control of the IgH locus in a teleost fish and to gain insight into the evolution of the control elements, the enhancer activity in the IgH locus of the channel catfish, Ictalurus punctatus, was investigated. Segments of the locus extending from upstream of the proximal JH gene to 2.5 kb downstream of the second transmembrane (TM2) exon of the mu gene were tested in transient transfection expression assays in murine myeloma and T cell lines, and in catfish B lymphoblastoid, monocyte-like, and putative T cell lines. In marked contrast to mammals, no enhancer activity was observed in the catfish JH to C mu intron, but strong enhancer activity (approaching that of the murine IgH intronic enhancer) was identified in a 1.8-kb segment that included the TM2 exon. This catfish enhancer was active in a B lineage-specific manner in both catfish and murine cells. It was not localized in a small core region, but appeared to contain multiple, dispersed cooperative elements rich in octamer- and mu E5-related motifs. Although the catfish IgH enhancer shares functional characteristics with the mammalian IgH intronic and 3' enhancers, its unusual organization does not permit any obvious inferences concerning evolutionary relationships between the catfish enhancer and any one of the murine IgH enhancers.

Animals↗
PubMed1976

[Evolutionary transformations of the esophageal lining in vertebrates and man in light of the theory of phylembryogenesis].

The comparative histological study of processes of embryonic histogenesis of the oesophagus epithelium in certain representatives of vertebrate animals (fishes, amphibia, reptiles, birds, mammals) and man was carried out in the light of the academician A. N. Severtsov's theory of phylembryogenesis. It has been shown that phylogenetic changes of the oesophagus lining of vertebrates related with its evolutionary transformations are regularly reflected in the stages or steps of the oesophagus epithelium histogenesis in ontogenesis of each systematic unit of the subtype. The first step is the phylembryogenesis of the oesophagus lining in all vertebrates is the monolayer epithelium of the endodermal origin; the secone step is the striated muco-ciliated (in low vertebrates and most reptiles) and pseudostratified (embryos of higher vertebrates) epithelium; the third step is the pseudostratified mucous epithelium (bony fishes) and stratified lining (prefetuses of higher vertebrates). The forth step is the stratified mucous (steppe turtle) and stratified muco-ciliated epithelium (fetuses of birds, many mammals and man). The fifth step--stratified squamous epithelium (birds, mammals, man). The academician A. N. Severtsov's theory of phylembryogenesis clearly points to the origins (the entoderm), routs and mechanisms of the transformation of the oesophagus lining in its evolutionary development.

Amphibians↗
PubMedDate not supplied

[Detection and analysis of Tetrahymena pyriformis 26S ribosomal DNA domain sequences, differing in degree of evolutionary conservation].

Domains of different evolutionary conservatism were defined in the 26S rDNA sequence of T. pyriformis. The fragment of studied DNA (1212 bp) showing high evolutionary conservatism was cloned. It was shown this fragment of DNA may be used to a probe for blot-hybridization analysis of the structure of rDNA from various taxa, protists to mammals. Superconservative and hypervariable domains were defined. The first are good for the primers for PCR analysis of rDNA from various taxa, the second--for species specific primers.

Animals↗
PubMed1995

The evolutionary origins of osteoarthritis: a comparative skeletal study of hand disease in 2 primates.

OBJECTIVE: To test the evolutionary hypothesis for joint failure by comparing the prevalence of osteoarthritis (OA) in 2 primate hands with different thumb usage. METHODS: We studied the hand skeletons of 32 humans and 32 macaques for OA. We defined OA as the presence of joint eburnation. RESULTS: The prevalence of OA in the distal interphalangeal joints was 26.7 and 50% for humans and monkeys, respectively. For the thumb base it was 37.5% in humans compared with 3.3% in macaques. The relative risk of thumb base OA in macaques may be due to the rudimentary design of the thumb. This finding supports the evolutionary hypothesis for joint failure and it may be applicable to many other joint sites.

Animals↗
PubMed1996

The functional conservation of proteins in evolutionary alleles and the dominant role of enhancers in evolution.

Drosophila paired- embryos can be rescued to viable adults by the evolutionary alleles prd-Gsb and prd-Pax3, which express the Drosophila Gooseberry and mouse Pax3 proteins under the control of the paired cis-regulatory region. As prd-Gsb uncovers a prd function involved in the proper abdominal segmentation of adults, evolutionary alleles, defined and constructed in this manner, may often be weak and thus serve to discover hitherto unknown functions of a gene. Our findings show that the Gooseberry and Pax3 proteins have conserved most or all functions of the related Drosophila Paired protein although their C-terminal halves appear unrelated in sequence but not in 3-D structure essential for function. It follows that the acquisition of new cis-regulatory regions rather than the divergence of the C-terminal coding regions has been the primary device for the functional diversification of the Drosophila genes paired and gooseberry and the mouse Pax3 gene. The operation of this mechanism in insects as well as vertebrates suggests a major role in evolution.

Alleles↗