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PubMed1988

Can we guarantee the safety of genetically engineered organisms in the environment?

Concern about the safety of genetically engineered organisms in the environment arises from the undesirable results of earlier new technologies and introduced organisms. Progress towards safe release is complicated by the varied views of a diverse society, confusion of process and product, problems with existing methods, and the lack of practical experience with real releases. No categorically safe novel organisms exist, but a progressive series of releases should allow risks to be systematically reduced.

Animals↗
PubMed1990

Quality assessment in the medical intensive care unit: evolution of a data model.

Quality assessment and assurance in the intensive care unit require systematic monitoring and evaluation of patient care and its outcome. For analysis of these activities, data must be organized to reflect changes in such factors as patient types, ages, and lengths of stay. A model was developed to group data from the Cleveland Clinic Hospital medical intensive care unit into structural, process, and outcome categories. Development and application of the model are described.

Data Collection↗
PubMed1977

Suid evolution and correlation of African hominid localities.

Recently discovered Plio-Pleistocene vertebrate assemblages have allowed complete systematic revision of the sub-Saharan African Suidae. New phylogenies are proposed for the 7 genera and 16 species of fossil and extant representatives. Suids are common elements of African Plio-Pleistocene faunas, and their evolutionary trends, particularly in the species Mesochoerus limnetes and Metridiochoerus andrewsi, are of great correlative value. Suid data are employed in a refinement of stratigraphic correlations at Omo Shungura, Olduvai, and east of Lake Turkana (formerly East Rudolf) and in a correlation of East African and South African sites, with important implications for interpretation of hominid evolution. The suid record also bears significantly on questions of theoretical evolutionary biology.

Africa↗
PubMed2004

Phylogeography of surface and cave Astyanax (Teleostei) from Central and North America based on cytochrome b sequence data.

Astyanax fasciatus has become a model organism for the study of regressive and adaptive evolution in cave animals. To fully understand these processes, it is important to have background information on the systematics and phylogeography of surface and cave populations of this species. Here we investigate the phylogeography of A. fasciatus in North and Central America and also the historical biogeography of this region. Phylogenetic analysis of part of the mtDNA cytochrome b gene from 26 surface and nine cave A. fasciatus populations revealed seven major clades, which, in principle, represent geographical patterns of distribution. However, the four strongly eye and pigment reduced cave populations, Piedras, Sabinos, Tinaja, and Curva, form a separate cluster, which is not sister group to the surface populations from the same locality. Similarly the Belizean populations do not cluster with their geographic neighbors from the Yucatan. The analyses indicate that there have been recurrent invasions of surface Astyanax from the south, that were most likely influenced by major climate changes during the Pleistocene. During this period, ancestors of the strongly eye and pigment reduced cave populations were able to survive underground as thermophilic relics when the surface populations became extinct. The high level of genetic divergence among the different clades shows that differing haplotype lineages must have reinvaded the surface waters from the south and/or back-colonized them from residual habitats and also penetrated into the caves. Nested clade analyses show that recurrent gene flow as well as historic processes like past fragmentation and range expansion have influenced current populations of A. fasciatus in Central and North America. Different haplotype clades of the phylogeny are not compatible with the present taxonomy of Astyanax and, therefore, we propose the application of a single systematic unit, called A. fasciatus.

Animals↗
PubMed2005

Site-saturation mutagenesis is more efficient than DNA shuffling for the directed evolution of beta-fucosidase from beta-galactosidase.

Protein engineers use a variety of mutagenic strategies to adapt enzymes to novel substrates. Directed evolution techniques (random mutagenesis and high-throughput screening) offer a systematic approach to the management of protein complexity. This sub-discipline was galvanized by the invention of DNA shuffling, a procedure that randomly recombines point mutations in vitro. In one influential study, Escherichia coli beta-galactosidase (BGAL) variants with enhanced beta-fucosidase activity (tenfold increase in k(cat)/K(M) in reactions with the novel para-nitrophenyl-beta-d-fucopyranoside substrate; 39-fold decrease in reactivity with the "native"para-nitrophenyl-beta-d-galactopyranoside substrate) were evolved in seven rounds of DNA shuffling and screening. Here, we show that a single round of site-saturation mutagenesis and screening enabled the identification of beta-fucosidases that are significantly more active (180-fold increase in k(cat)/K(M) in reactions with the novel substrate) and specific (700,000-fold inversion of specificity) than the best variants in the previous study. Site-saturation mutagenesis thus proved faster, less resource-intensive and more effective than DNA shuffling for this particular evolutionary pathway.

Base Sequence↗
PubMed2005

Molecular research and the control of Chagas disease vectors.

Chagas disease control initiatives are yielding promising results. Molecular research has helped successful programs by identifying and characterizing introduced vector populations and by defining intervention targets accurately. However, researchers and health officials are facing new challenges throughout Latin America. Native vectors persistently reinfest insecticide-treated households, and sylvatic triatomines maintain disease transmission in humid forest regions (including Amazonia) without colonizing human dwellings. In these scenarios, fine-scale vector studies are essential to define epidemiological risk patterns and clarify the involvement of little-known triatomine taxa in disease transmission. These eco-epidemiological investigations, as well as the planning and monitoring of control interventions, rely by necessity on accurate taxonomic judgments. The problems of cryptic speciation and phenotypic plasticity illustrate this need--and how molecular systematics can provide the fitting answers. Molecular data analyses also illuminate basic aspects of vector evolution and adaptive trends. Here we review the applications of molecular markers (concentrating on allozymes and DNA sequencing) to the study of triatomines. We analyze the suitability, strengths and weaknesses of the various techniques for taxonomic, systematic and evolutionary investigations at different levels (populations, species, and higher taxonomic categories).

Animals↗
PubMed1989

Cytological approaches to simuliid biosystematics in relation to the epidemiology and control of human onchocerciasis.

This paper presents an overview of advances in cytological research on the biosystematics of vector simuliid complexes in the areas of identification, age grading, and the evolution of resistance in relation to the epidemiology and control of human onchocerciasis. Systematic theory is discussed and relevant examples are given to show its application in predicting and resolving current problems in species identification for New World and Old World vector complexes. These complexes include Simulium damnosum s.l. and S. neavei s.l. from Africa and S. exiguum s.l., S. metallicum s.l., S. ochraceum s.l., and S. oyapockense s.l. from Latin America. The evolution of resistance in S. damnosum s.l. and the need for future molecular research as part of resistance management strategies are discussed.

Africa↗
PubMed2000

Molecular mechanisms in myelodysplastic syndromes and implications for evolution to acute leukemias.

This article reviews the molecular lesions that occur in the clonal hematopoietic disorders classified as myelodysplastic syndromes (MDS). A systematization of these molecular lesions is attempted based on the types of molecular abnormalities. Characteristically, these molecular lesions affect pluripotent hematopoietic progenitors and therefore affect myeloid, monocytic, erythroid, and megakaryocytic lineages. Progression of MDS to acute myelogenous leukemia is common; transformation is considered the final stage in the multi-step process of accumulation of molecular lesions over a prolonged latency period of MDS evolution. Although no molecular lesion is MDS specific, multiple combinations of molecular lesions are common and a systematic approach based on the type of molecular abnormality may offer a better understanding of MDS pathogenesis and the basis for new therapeutic strategies.

Acute Disease↗
PubMed2003

Molecular estimation of eulipotyphlan divergence times and the evolution of "Insectivora".

"Insectivores" are one of the key groups in understanding mammalian origins. For years, systematics of "Lipotyphla" taxa remained extremely unstable and challenged. Today, with the application of molecular techniques, "Lipotyphla" appears to be a paraphyletic assemblage that encompasses hedgehogs, shrews, and moles (i.e., Eulipotyphla-a member of Laurasiatheria), and golden moles and tenrecs (i.e., Afrosoricida-a member of Afrotheria). Based on nuclear genes and on this well-established phylogenetic framework, we estimated Bayesian relaxed molecular clock divergence times among major lineages of "Lipotyphla." Crown placental mammals are shown to diversify 102+/-6 million years ago (Mya; mean+/-one standard-deviation), followed by Boreoeutheria (94+/-6 Mya), Laurasiatheria (85+/-5 Mya), and Eulipotyphla (73+/-5), with moles separating from hedgehogs+shrews just at the K/T boundary (65+/-5 Mya). During the Early and Middle Eocene, all extant eulipotyphlan subfamilies originated: Uropsilinae (52+/-5 Mya), and Desmaninae, Talpinae, Erinaceinae, Hylomyinae, Soricinae, and Crocidurinae (38-42+/-5 Mya). Afrosoricida separated from Macroscelidae 69+/-5 Mya, golden moles from tenrecs 63+/-5 Mya, and the diversification within tenrecs occurred 43+/-5 Mya. Divergence times are shown to be in reasonably good agreement with the fossil record of eulipotyphlans, but not with the one of afrosoricid "insectivores." Eulipotyphlans diversification might have been sculpted by variations in paleoclimates of the cenozoic era.

Animals↗
PubMed1989

[Primary malignant melanoma of ORL mucosa. Apropos of 5 cases].

Based on five observations of primary mucosal melanomas recently treated in the department, the authors describe the main features of this very rare condition, and particularly the evolutive aspects in diagnosis and prognosis. Histological diagnosis is sometimes difficult, and must involve specific argentic staining and a search for the presence of the protein S100. Tumor thickness was systematically examined. No prognostic interpretation, however, is possible, given the small number of cases in the series. Evolution is unpredictable; there is very commonly a series of local recurrences which may be well controlled, followed by remote metastases remaining long quiescent, bypassing the cervical ganglion relay. Treatment is surgical whenever possible, with palliative radiotherapy for local recurrences and chemotherapy for metastatic forms. Other therapies have yet to prove their effectiveness.

Aged↗
PubMedDate not supplied

[Genes controlling inflorescence structure and their possible role in evolution].

Structural features of the shoot system and inflorescence are the most important morphological features, on which plant systematics are based. The present review provides information on the genetic control of shoot morphogenesis in the model plant Arabidopsis thaliana. The results obtained made it possible to reveal a small group of genes responsible for the main taxonomic features of the shoot structure in this species. Cloning of these genes opened new avenues for directed search of homologous genes in other plants. Comparative analysis of the shoot structure and studies of the function and expression of these genes in various plants suggest that morphological evolution may be based on changes in the pattern of expression of single regulatory genes.

Biological Evolution↗
PubMed1976

New karyological data of Rhinoderma: the chromosomes of Rhinoderma rufum.

The chromosomes of the Chilean frog Rhinoderma rufum are described for the first time. This chromosome set is compared with the karyotype of R. darwinii. The importance of the karyological data applied to the phylogeny and systematics of this genus are discussed. A tentative hypothesis of karyological evolution of Rhinoderma is given.

Animals↗
PubMed2002

Molecular phylogeny of cycads inferred from rbcL sequences.

The chloroplast gene rbcL was sequenced to elucidate the evolution of the gymnosperm plant order Cycadales. In accordance with traditional systematics, the order Cycadales and the corresponding genera cluster as monophyletic clades. Among them, the genus Cycas forms a basal group. The genetic distances within the genus Encephalartos and between the sister groups Encephalartos, Lepidozamia and Macrozamia, are unexpectedly small, suggesting that the extant species are the result of Miocene and Pliocene speciation. Their distribution in Africa or Australia, respectively, may therefore rather be due to long-distance dispersal than to Cretaceous continental drift, as had previously been assumed. The rbcL sequences also indicate that the colonisation of Madagascar by Cycas thouarsii occurred only recently as the sequences of C. thouarsii and Cycas rumphii from Indonesia are identical. In contrast, the divergence of the Cycadaceae and Zamiaceae apparently occurred in the Mesozoic.

Cycadopsida↗