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PubMed1990

How gene families evolve.

Theories and facts of gene family evolution are reviewed. Concerted evolution is commonly observed for gene families which originated a long time ago, however there are many different types of multigene families, from uniform to diverse. The rate of homogenization by unequal crossing-over, gene conversion, etc. has been evolutionarily adjusted for each gene family. When new functions are needed by organisms, gene families may evolve into superfamilies, in which no further concerted evolution takes place, and each member of the family may acquire an indispensable function. The homeobox-containing gene family is a most exciting example of such superfamily.

Animals↗
PubMed1992

Genetic evidence that epizootic Venezuelan equine encephalitis (VEE) viruses may have evolved from enzootic VEE subtype I-D virus.

An important question pertaining to the natural history of Venezuelan equine encephalitis (VEE) virus concerns the source of epizootic, equine-virulent strains. An endemic source of epizootic virus has not been identified, despite intensive surveillance. One of the theories of epizootic strain origin is that epizootic VEE viruses evolve from enzootic strains. Likely enzootic sources of VEE virus occur in Colombia and Venezuela where many of the epizootic outbreaks of VEE have occurred. We have determined the nucleotide sequences of the entire genomes of epizootic VEE subtype I-C virus, strain P676, isolated in Venezuela, and of enzootic VEE subtype I-D virus, strain 3880, isolated in Panama. VEE subtype I-D viruses are maintained in enzootic foci in Panama, Colombia, and Venezuela. The genomes of P676 and 3880 viruses differ from that of VEE subtype I-AB virus, strain Trinidad donkey (TRD), by 417 (3.6%) and 619 (5.4%) nucleotides, respectively. The translated regions of P676 and 3880 genomes differ from those of TRD virus by 54 (1.4%) and 66 (1.8%) amino acids, respectively. This study and the oligonucleotide fingerprint analyses of South American I-C and I-D viruses (Rico-Hesse, Roehrig, Trent, and Dickerman, 1988, Am. J. Trop. Med. Hyg. 38, 187-194) provide the most conclusive evidence to date suggesting that equine-virulent strains of VEE virus arise naturally from minor variants present in populations of I-D VEE virus maintained in enzootic foci in northern South America.

Amino Acid Sequence↗
PubMed1990

Myofibroblastoma of the tunica testis: evolving phase of so-called fibrous pseudotumor?

A collagen-rich stromal tumor attached to the testicular tunica albuginea of a 22-year-old male is reported. Immunocytochemical and ultrastructural characterization revealed a predominant population of myofibroblasts, an as yet unrecognized observation in tumors arising from testicular tunics. The possible relationship with so-called fibrous pseudotumor (nodular fibrous proliferation) is discussed. The myofibroblastic nature of the cell population would support the hypothesis of a reactive contractile process if one accepts this tumor as an evolving phase of fibrous pseudotumor.

Adult↗
PubMed1992

Longitudinal Gompertzian analysis of emphysema mortality in the US, 1962-1987: the differing basis for evolving mortality patterns in men and women.

Age-specific mortality rates for emphysema in the United States from 1962 through 1987 were subjected to longitudinal Gompertzian analysis, a method that can be used to identify and distinguish aggregate genetic, environmental, and competitive influences upon mortality. Annual crude emphysema mortality rates (per 100,000) among men increased from 11.77 in 1962 to 20.94 in 1968, and then fell to 7.74 in 1987. The basis for this rise and fall is shown to be the corresponding changes in environmental influences upon emphysema mortality in men. Between 1962 and 1987, the annual crude emphysema mortality rates among women increased from 1.71 to 4.25. The basis for the increase of emphysema mortality in women, on the other hand, is shown to be an enhancement of the competitiveness of emphysema as a cause of mortality in women, and not the result of worsening environmental influences. The capability to distinguish between environmental and competitive influences upon evolving human mortality patterns could have a significant impact upon public health policy.

Adult↗
PubMed1995

Characterization of 7q--by FISH technique of a case with acute myelogenous leukemia evolving from agnogenic myeloid metaplasia.

We present a new case of acute myelogenous leukemia (AML) which evolved from agnogenic myeloid metaplasia (AMM). Routine cytogenetic techniques revealed a terminal deletion of one chromosome 7 (del (7) (q21)). When metaphases were hybridized with the 7q specific telomeric probe, a signal was detected at the distal q arm of the deleted chromosome 7 suggesting an interstitial deletion and the cytogenetic diagnosis was changed to 46,XY, del(7) (q21.1q36.2). Apparently, precise characterization of such deletions may have gone undetected, owing to the lack of technology, and deletions that have been previously regarded as terminal may very well be interstitial. Undoubtedly, precise identification of genetic abnormalities may lead to a better classification which may help to assign patients into sub-subgroups within the specific chromosomal abnormalities to initiate better therapeutic modalities and decisions.

Chromosome Deletion↗
PubMed1990

Headspace determination of evolved carbon dioxide in a biodegradability screening test.

A headspace method to measure the carbon dioxide evolved in a screening biodegradability test is described. Use was made of conventional serum bottles, sealed with butyl rubber septa, through which headspace samples were taken after acidification and equilibration of the test solution. For each determination a serum bottle was sacrificed. The gas samples were injected directly into the reaction chamber of a carbon analyzer. Eighteen chemicals varying in solubility and biological properties were submitted to the test. Where possible, mineralization of test compounds was monitored through dissolved organic carbon analysis in addition to CO2 analyses. The reliability of the method was verified by comparing the measured concentration of dissolved inorganic carbon of a standard sodium carbonate solution with values calculated from measured concentrations of carbon dioxide in the headspace after acidification. Results of biodegradability testing are discussed in view of the suitability of the method to poorly soluble compounds.

Biodegradation, Environmental↗
PubMed1987

Chromosomal subclonal evolution in paroxysmal nocturnal hemoglobinuria evolving into acute megakaryoblastic leukemia.

Four cytogenetic studies were performed in the course of a paroxysmal nocturnal hemoglobinuria evolving into acute megakaryoblastic leukemia. The clonal evolution was characterized by a unique structural change (9p) at the time of diagnosis, heralding an accelerated and complex karyotypic alteration including 5q-, 12p-, +21, -5, -7. At the terminal phase, the initial population was replaced within 1 week by a new overgrowing clone with -5, +8, +17. This suggests that the paroxysmal nocturnal hemoglobinuria-associated preleukemia and leukemic states share with acute nonlymphocytic leukemia the same nonrandom chromosomal changes.

Adult↗
PubMed1988

Translocation (8;16)(p11;p13) in patients with acute monocytic leukemias. An evolving syndrome?

The case of a patient with a t(8;16)(p11;p13) chromosomal abnormality and acute myelomonocytic leukemia is described. Review of cases with this translocation showed that 11 of 13 patients had acute monocytic or myelomonocytic leukemia with a high frequency of extramedullary disease and phagocytosis of normal blood cells by the malignant cells. While these patients are not clinically distinct from others with acute monocytic leukemia, the characteristic features of this subset of patients will certainly evolve.

Adolescent↗
PubMed1988

Translocation (2;7)(p13;q36) in a case of acute nonlymphocytic leukemia evolving from a myelodysplastic syndrome.

A case of acute nonlymphocytic leukemia with a new translocation, t(2;7)(p13;q36), as the sole karyotypic abnormality is reported. The patient's leukemia evolved from a cytogenetically normal myelodysplastic syndrome of 4 years' duration. Following treatment the patient entered complete remission with loss of the cytogenetically abnormal clone. Subsequent bone marrow analyses showed recurrence of the myelodysplastic syndrome with a normal karyotype. Although both chromosomes 2 and 7 are known to be involved in nonrandom karyotypic changes in human cancer and leukemia, t(2;7)(p13;q36) has not been reported previously.

Aged↗
PubMed1993

Chromosome analysis of adenomatous polyps of the colon: possible existence of two differently evolving cytogenetic groups.

A chromosomal study of 42 colonic adenomatous polyps was performed using a technique of direct chromosome analysis derived from the prenatal procedure for diagnosing chromosomal alterations from chorionic villi sampling. Abnormal karyotypes were found in 22 cases. Trisomy 7, the most frequently found alteration, was found in 13 cases, followed by trisomy 13 (nine cases). Monosomy 18 was observed in two cases; in one of these, that of a polyp which had degenerated into an intra-mucosal adenocarcinoma, it was associated with 17p monosomy. Interestingly, these two types of alterations (trisomy 7 versus 18 and 17p monosomy) were not found together in the same lesion. This suggests that there could be two distinct chromosomal behaviors which might be related to the two cytogenetic groups described for colorectal adenocarcinoma. However, the respective frequencies of such cytogenetic groups varied inversely between adenomas and adenocarcinomas, thus suggesting that they evolve differently.

Adult↗
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↗
PubMed1992

Symbiotic interactions in the EVOLVE III ecosystem model.

Parasitic feeding mechanisms were introduced into the EVOLVE III ecosystem model. The modified system exhibited a number of interesting behaviors, including obligative and facultative parasitism, transient facultative mutualism and nonsymbiotic feeding. Speciation and massive die-offs were also observed. The introduction of a symbiotic capability altered the co-evolutionary development of traits that exhibited an arms race when the symbiotic capability was not present. Stable mutualisms were not possible in the present version of the model due to the restriction that organisms were not allowed to feed both on other organisms and from the environment at the same time. The ecosystem biomass increased with increased symbiotic activity. Biomass was influenced by the balance of virulence and resistance traits in the population and decreased as these traits became more disparate.

Animals↗
PubMed1996

Evolving continuous behaviors in the Iterated Prisoner's Dilemma.

Evolutionary programming experiments are conducted on a variant of the Iterated Prisoner's Dilemma. Rather than assume each player having two alternative moves in the stage-game, cooperate or defect, a continuum of possible moves are available. Players' strategies are represented by feed-forward perceptrons with a single hidden layer. The population size and the number of nodes in the hidden layer are varied across a series of experiments. The results of the simulations indicate a minimum amount of complexity is required in a player's strategy in order for cooperation to evolve. Moreover, under the evolutionary dynamics of the simulation, cooperation does not appear to be a stable outcome.

Communication↗
PubMed1993

Transthyretin expression evolved more recently in liver than in brain.

1. Transthyretin was found to be synthesized and secreted by choroid plexus from rats, echidnas, and lizards, but not toads. 2. Transthyretin was observed in blood from placental mammals, birds, and marsupials, but not reptiles and monotremes. 3. The obtained data suggest that transthyretin synthesis by the liver evolved independently in the lineage leading to the placental mammals and marsupials and in that leading to the birds. 4. It is proposed that transthyretin gene expression in mammalian liver appeared about 200 million years later than its first occurrence in the choroid plexus of the stem reptiles.

Amino Acid Sequence↗
PubMed1984

Role of chemotherapy in the treatment of lung cancer: evolving strategies for non-small cell histologies.

Lung cancer treatment has been considered to have made little progress except for advances in small cell carcinoma. For other histologies an attitude of nihilism has prevailed principally because of lack of effective systemic therapy and of no persuasive evidence that results could be improved by combined modality treatment. On the other hand, favorable results from surgery are confined to a small percent of all patients with this disease. This review emphasizes possibilities for progress in evolving new therapeutic strategies. Although improvement over other systemic therapies is modest, cisplatin-containing regimens yield more consistent response rates and apparent survival advantage relative to single agents. Immediate progression occurs in the minority of patients. In addition, regimens combining cisplatin with vinca alkaloids have no substantial deleterious effects on the lung, marrow or esophagus to aggravate radiation-induced complications. These features encourage the evolution of strategies which begin with chemotherapy and then use consolidation with radiation therapy. Clinical trials using these and newer strategies must be instituted if progress is to occur in the treatment of non-small cell histologies at all stages.

Adenocarcinoma↗
PubMed1995

A growth-defective kirromycin-resistant EF-Tu Escherichia coli mutant and a spontaneously evolved suppression of the defect.

This study has investigated the cause of a growth-defect phenotype of a mutation in the elongation factor EF-Tu from Escherichia coli. An M13-based genetic retrieval system reported by Zeef and Bosch [Mol. Gen. Genet. 238 (1993) 252-260] was used to segregate and identify an extremely growth-defective kirromycin-resistant (KrR) tufA mutation, encoding Gln124-->Lys (Q124K), from a KrR parent strain. This original strain also contained mutations, 124com1 and 124com2, that appear to have evolved to suppress the Q124K tufA mutation. In this communication we present these M13-based genetic experiments together with additional genetic and protein characterization experiments to clarify the basis of this complementation. The data indicate that the serious growth defect of Q124K originates from a defective GTP/GDP interaction. The GTP/GDP binding and GTP hydrolysis characteristics of ET-Tu Q124K were different from wild-type EF-Tu and especially of another KrR EF-Tu mutant A375T. In line with this, 124com1 specifically complemented EF-Tu Q124K, whereas the growth defects of strains containing EF-Tu mutated at aa 375 were aggravated. We also show that strains containing the segregated tufA Q124K mutation formed filaments.

Anti-Bacterial Agents↗
PubMedDate not supplied

Echographic patterns of just evolving acute pancreatitis: an experimental study.

The earliest echographic manifestations of just evolving acute pancreatitis were studied in five dogs. Fifteen minutes after induction of acute pancreatitis, the pancreas was excised. Serial echographic and microscopic cuts were performed in exactly corresponding levels of each pancreas. In all slices containing a pancreatic necrosis of 50% or more, the echographic pattern was abnormal. In extended pancreatic necrosis (i.e., 75-100% necrosis), a characteristic sonographic pattern could be observed, allowing differentiation from interstitial acute pancreatitis and minor necroses.

Acute Disease↗