Developmental homologues: lineages and analysis

Developmental processes present several problems for identifying homologies and analyzing their evolution. Most evolutionary techniques approach homologies from either a taxonomic or a molecular perspective. Approaches that can accommodate many problems of developmental evolution are not well developed. Developmental process and evolutionary lineage complexity lead to a number of largely unappreciated conceptual and analytic problems. Developmental processes can evolve by duplication or diversification. Each process is in a hierarchy of super- and subprocesses. As they evolve, process components may be exchanged with or acquired by those of other processes. Because they do not fit into standard analytic procedures, these situations (including reticulate or reticulate-appearing lineages, partial homologues, iterative features, and the tracing of nontaxonomic and nonmolecular evolutionary lineages) are often ignored or considered illegitimate. Biology's disdain for the dichotomously branching phylogenetic lineages that are the basis of standard analytic approaches is ignored at the risk of making falsely negative homology evaluations. I will present an approach that can accommodate analyses of these situations. The use of nontaxonomic and nonmolecular lineages provides a way to structure comparisons between other entities, as taxonomic lineages structure comparisons among potential homologues. From an informational point of view, any entity (either a structure or process) with an evolutionary history is a potential homologue with a potential evolutionary lineage. Comparing lineages of interacting entities can reveal topological incongruences among them. Methods that identify reticulated taxonomic and molecular lineages should also apply to other lineages. Partial homologues, resulting from reticulated lineages, can be handled in several possible ways. Analytically, such an entity can be treated as a partial homologue, a novel feature, an independent sub-unit, or a unitary feature homologous to the major contributor of its inherited features.     

基于遗传算法的土壤环境进化分析

随着各种工程建设项目的迅速崛起，土壤环境污染的现象日益普遍和严重，亦引起了人们的高度重视。文中应用遗传算法理论，对土壤污染因子与土壤污染元素的年积累量进行优化，可以减缓土壤的污染强度，延长土壤环境容量的服务年限；节约水资源，降低生产成本。     

A small-scale survey of hantavirus in mammals from Indiana

In order to determine if hantaviruses were present in mice and other small mammals in Indiana (USA), small mammals were trapped in Brown, LaPorte, Tippecanoe and Whitley counties. Sixty-seven small mammals were trapped during August and September 1994. Sixty-three Peromyscus leucopus, one Microtus pennsylvanicus, one Zapus hudsonius and two Blarina brevicauda were captured and tested for hantaviruses. Six P. leucopus were found to have antibody to Sin Nombre virus (SN) by IgG ELISA, and a 139 bp fragment of SN-like hantavirus was amplified from five of them. All six of the positive P. leucopus were from LaPorte County. No other small mammals had evidence of infection with SN virus. This study presents the first report of Sin Nombre-like hantavirus in P. leucopus from Indiana.     

Isolation and initial characterization of a newfound hantavirus from California

A fatal case of hantavirus pulmonary syndrome (HPS) in northern California prompted our attempt to isolate viruses from local rodents. From tissues of two deer mice, Peromyscus maniculatus, two hantaviruses (Convict Creek virus 107 and 74, CC107 and CC74) were established in cell culture. Viral antigens, proteins, and RNAs of the first and archetypical isolate (CC107) were examined, and portions of the medium (M) and small (S) genome segments of both isolates were sequenced. Antigenically, CC107 virus and the second isolate, CC74 virus, were more closely related to Puumala virus than Hantaan (HTN) virus, though distinct from both. Northern blots of viral RNAs showed the large and M segments of CC107 to be the same size as those of HTN virus, whereas the S segment was larger. Protein gels did not reveal CC107 to have a substantially larger nucleocapsid protein than HTN virus. Partial nucleotide sequence comparisons of CC107 and CC74 viruses revealed their M segments to be highly similar to one another, while their S segments differed by more than 10%. Nucleotide and deduced amino acid sequence comparisons showed the California isolates to be closely related to the newfound hantaviruses first detected in the Four Corners area and since incriminated in HPS through wide areas of the United States.     

Common patterns of genetic evolution in human solid tumors

Microscopy is a basic tool for cell biologists. Recent progress of electronics and computer science made powerful methodologies for digital processing of microscopic images easily available. These methods allowed impressive increase of the power of conventional microscopy. Dramatic image enhancement may be achieved by combination of filtering techniques, computer-based deblurring and contrast enhancement. Quantitative treatment of digitized images allows absolute determination of the density of different components of the observed sample, including antigens, intracellular calcium and pH. Morphometric studies are also greatly facilitated by image processing techniques. The capture of fast phenomena may be performed by transfer of small portion of microscopic images into computer memory as well as particular use of confocal microscopy. Finally, improved display of experimental data through coded colors or other procedures may enhance the amount of information that can be conveyed by visual examination of microscopical images. The purpose of the present review is to describe the basic principles of image processing and exemplify the power of this approach with a variety of illustrated applications to conventional, fluorescence or electron microscopy as well as confocal microscopy.     

A system of immunoenzyme analysis using biotinylated monoclonal antibodies for typing hantavirus antigens

Enzyme immunoassay with biotin-labeled monoclonal antibodies to Puumala virus was used for typing hantavirus antigens. The system is type-specific, that is, it detects Puumala virus only, which was demonstrated by typing 9 hantavirus antigens in infected Vero E5 cells and by epizootological analysis of an HFRS outbreak in the Yegoryevsk district of the Moscow region in November-December 1995. The suggested system may be used as an element of EIA screening of natural samples in analysis of the screening results.     

Genetic studies in Medzev, an isolate in south-eastern Slovakia. 2. Distribution of blood group genetic markers

Phenotype and gene frequencies of three blood group, four serum protein and seven red cell enzyme polymorphisms were examined in 105 individuals from the population of Medzev, South-Eastern Slovakia. Locus and allele specific tests of homogeneity were calculated in order to obtain the pattern of variation. The results indicate considerable genetic differences between this population and another local population of this region (Chmelnica) as well as between the Medzev population and the total population of Slovakia. The possible reasons of the genetic heterogeneity within Slovakia are discussed.     

Experimental transmission of hantavirus infection in laboratory rats

This study found a competent transmission of hantavirus between cagemates using congenitally T cell-deficient Rowett nude rats (rnu/rnu). Intraperitoneally infected immunologically normal rats (rnu/+) did not transmit the hantavirus to their normal cagemates (rnu/+) but did to Rowett nude rats (rnu/rnu). Thus, nude rats were shown to be highly susceptible to the hantavirus infection. Also, infected nude rats (rnu/rnu) discharged the infectious viruses, to cause a prevalence of infection among normal cagemates (rnu/+). The infection system demonstrated here using Rowett rats (rnu/rnu) may provide a useful model to study the mechanism of the hantavirus infection.     

Melanocyte culture lines from Tyr-SV40E transgenic mice: models for the molecular genetic evolution of malignant melanoma

Transgenic Tyr-SV40E mice previously produced on the C57BL/6 inbred-strain background, with SV40 oncogenic sequences specifically expressed in pigment cells, are predisposed to melanoma [Bradl, M., Klein-Szanto, A., Porter, S. & Mintz, B. (1991). Proc. Natl. Acad. Sci. USA, 88, 164-168]. Separate lines of these animals differ genetically only in the number of copies and chromosomal site of integration of the transgene. Skin melanocytes from young mice with no apparent skin lesions were established in continuous culture from hemizygous donors with low, medium and high numbers of transgene copies, and from a homozygous offspring of the low-copy mouse line. The standard culture conditions enable C57BL/6 wild-type melanocytes to become stably immortalized without transformation. The transgenic cell lines all changed over time in an orderly progression. However, with greater numbers of transgene copies, the cells more rapidly displayed shorter doubling times, increased anchorage independence, reduced serum and growth factor requirements, decreased tyrosinase expression and melanin content, increased oncogene expression, and capacity to form malignant melanomas when tested by grafting. Melanocytes with the lowest number of transgene copies were of special interest. They grew more rapidly than the wild-type cells from the outset, but did not become tumorigenic until an apparently small number of still-unknown genetic changes had spontaneously occurred, or until the number of transgene copies was increased slightly by homozygosity. In contrast to the hemizygous low-copy cells, the homozygous counterparts underwent striking and rapid transformational changes and early conversion to malignancy. Thus such low-copy transgenic melanocyte lines afford an exceptional opportunity for molecular analysis of somatic genetic evolution toward malignant melanoma.     

Personality and divorce: a genetic analysis

M. McGue and D.T. Lykken (1992) found that divorce risk was, to a substantial degree, genetically mediated; prior research has identified numerous social and psychological factors that affect divorce risk (G.C. Kitson, K.B. Barbi, & M.J. Roach, 1985). The present study attempted to link these domains by examining the extent to which genetic influences on one such psychological factor, personality, explain divorce risk heritability. A sample of adult twins from the Minnesota Twin Registry completed a marital history questionnaire and the Multidimensional Personality Questionnaire (A. Tellegen, 1982). Positive Emotionality and Negative Emotionality factors were positively related to divorce risk, whereas Constraint was negatively related. In women and men, respectively, 30% and 42% of the heritability of divorce risk consisted of genetic factors affecting personality and divorce risk correlated largely as a result of these common genetic influences.     

Attitudes towards genetic testing: analysis of contradictions

A survey study was conducted among 1169 people to evaluate attitudes towards genetic testing in Finland. Here we present an analysis of the contradictions detected in people's attitudes towards genetic testing. This analysis focuses on the approval of genetic testing as an individual choice and on the confidence in control of the process of genetic testing and its implications. Our analysis indicated that some of the respondents have contradictory attitudes towards genetic testing. It is proposed that contradictory attitudes towards genetic testing should be given greater significance both in scientific studies on attitudes towards genetic testing as well as in the health care context, e.g. in genetic counselling.     

Hierarchical analysis of genetic structure in native fire ant populations: results from three classes of molecular markers

We describe genetic structure at various scales in native populations of the fire ant Solenopsis invicta using two classes of nuclear markers, allozymes and microsatellites, and markers of the mitochondrial genome. Strong structure was found at the nest level in both the monogyne (single queen) and polygyne (multiple queen) social forms using allozymes. Weak but significant microgeographic structure was detected above the nest level in polygyne populations but not in monogyne populations using both classes of nuclear markers. Pronounced mitochondrial DNA (mtDNA) differentiation was evident also at this level in the polygyne form only. These microgeographic patterns are expected because polygyny in ants is associated with restricted local gene flow due mainly to limited vagility of queens. Weak but significant nuclear differentiation was detected between sympatric social forms, and strong mtDNA differentiation also was found at this level. Thus, queens of each form seem unable to establish themselves in nests of the alternate type, and some degree of assortative mating by form may exist as well. Strong differentiation was found between the two study regions using all three sets of markers. Phylogeographic analyses of the mtDNA suggest that recent limitations on gene flow rather than longstanding barriers to dispersal are responsible for this large-scale structure.     

Further study of hantavirus circulation in the Russian Federation

Lung specimens of 1514 small mammals of 35 species captured in 1991-1995 at 9 territories of Russia were tested in ELISA for virus antigens of hemorrhagic fever with the renal syndrome (HFRS). The antigens were detected in lung specimens of Clethrionomys glareolus, Microtus arvalis, Microtus gregalis, Microtus fortis, Arvicola terrestris, Apodemus agrarius, Micromys minutus, and Sorex sp., well known as Hantavirus reservoirs, captured in the Vologda, Yaroslavl, Saratov, Astrakhan, and Chita regions. Infection of Microtus maximoviczii revealed in the Chita region was first found in China. Previously there were no reports about the circulation of hantaviruses in this region. Our study added one more host to the list of HFRS virus hosts: Meliones tamariscinus.     

Tryptophan biosynthesis in Coprinus lagopus: a genetic analysis of mutants

Thirty-one tryptophan-requiring mutants of Coprinus lagopus have been assigned by genetic and complementation analyses to four loci designated trp-I, trp-2, trp-3 and trp-4. The trp-1 and trp-3 loci were located in group III and trp-2 in group G of the linkage map. The trp-4 locus showed no linkage to the other trp loci or to markers in three additional linkage groups tested. From auxanographic tests and a study of accumulated biosynthetic intermediates, the enzymes controlled by each locus have been provisionally assigned. The trp-2 and trp-3 loci both appear necessary for anthranilate synthetase activity since mutants accumulated no intermediates. Only the trp-3 mutant could utilize anthranilic acid, therefore the trp-2 locus must also be involved in a subsequent step in the pathway. The trp-4 mutants utilized indole and accumulated anthranilic acid, and hence this locus is involved in the conversion of anthranilic acid to indoleglycerol phosphate. The trp-1 mutants utilized only tryptophan and accumulated indoleglycerol phosphophate and anthranilic acid. They are therefore blocked in the final steps of the pathway catalysed by tryptophan synthetase.     

Preimplantation genetic analysis of translocations: case-specific probes for interphase cell analysis

Carriers of balanced translocations show an increased risk of infertility and spontaneous abortions, because of errors in gametogenesis, and constitute a significant fraction of patients seeking assisted reproduction. The objective of this study was to design approaches for preimplantation diagnosis of chromosome translocations and to apply such techniques to the selection of chromosomally normal or balanced embryos prior to their transfer to the mother's womb. Three slightly different approaches were assessed by means of chromosome-specific, non-isotopically labeled DNA probes and an assay based on fluorescence in situ hybridization- to score and characterize chromosomes in single blastomeres biopsied from embryos on their third day of development. The three approaches were used for preimplantation genetic diagnosis involving four couples who had enrolled in our IVF program and in which one of the partners was a carrier of one of the following translocations: 46,XX,t(12;20)(p 13.1 ;q 13.3), 46,XY,t(3;4) (p24;p15), 45,XY,der(14;15)(10q;10q), and 46,XY,t(6;11) (p22.1;p15.3). A total of 33 embryos were analyzed, of which 25 (75.8%) were found to be either unbalanced or otherwise chromosomally abnormal. Only a single embryo could be transferred to patients A and D, whereas three embryos were transferred to patient B in a total of two IVF cycles. Transfer of two embryos to patient C resulted in an ongoing pregnancy. Re-analysis of non-transferred embryos with additional probes confirmed the initial results in 95% (20/21) of the cases. In conclusion, case-specific translocation tests can be applied to any translocation carrier for the selection of normal or chromosomally balanced embryos prior to embryo transfer. This is expected significantly to increase the success rates in IVF cycles of translocation carriers, while preventing the spontaneous abortion or birth of abnormal offspring.     

Facing death in the fly: genetic analysis of apoptosis in Drosophila

Apoptosis, a gene-directed form of cell death, occurs normally during development and plays a major role in many diseases, including cancer and neurodegenerative disorders. Molecular genetic studies in Drosophila have revealed the existence of three novel apoptotic activators, reaper, head involution defective and grim. Additionally, Drosophila homologs of evolutionarily conserved IAPs (inhibitor of apoptosis proteins) and CED-3/ICE-like proteases have been identified and characterized. Through the combined use of genetic, molecular, biochemical and cell biological techniques in Drosophila it should now be possible to elucidate the precise mechanism by which apoptosis occurs, and how the death program is activated in response to many distinct death-inducing signals.