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PubMed1988

Origins and organization of genetic diversity in natural populations of Trypanosoma brucei.

Experimental work has established that a sexual process can occur in African trypanosomes (Jenni, Marti, Schweizer, Betschart, Le Page, Wells, Tait, Paindavoine, Pays & Steinert, 1986; Paindavoine, Zampetti-Bosseler, Pays, Schweizer, Guyaux, Jenni & Steinert, 1986; Tait, personal communication). However, the role of the process in natural populations of trypanosomes is poorly understood. This paper considers what information can be gained from analyses of isoenzyme polymorphism. A cladistic approach is used to help determine whether trypanosome diversity could have been produced by mutation alone. When applied to three East African populations of Trypanosoma brucei it provides evidence that some diversity has arisen through a sexual process; this explains the variation observed within a locality and can account for the evolution of differences between localities. However, the extent to which genetic exchange currently operates is less clear. Analysis of genotype frequencies indicates that agreements with Hardy-Weinberg expectations can be obtained even if genetic exchange exerted no influence over genotype frequencies. Moreover, analysis of joint locus frequencies reveals disequilibrium between loci and that trypanosome populations may be lacking several genotype combinations. Thus, genetic exchange may not occur sufficiently frequently, or in such a way as to break up associations between loci. The relevance of these observations to the evolution of strain differences within T. brucei is discussed.

Alleles↗
PubMed1995

Ecological, morphological and genetic characterization of sympatric Haemonchus spp. parasites of domestic ruminants in Mauritania.

The 4 species of ruminants (dromedary, zebu cattle, sheep and goat) in arid areas of Mauritania harboured Haemonchus spp. as the most frequent internal parasite. This was a rare situation where the 3 putative species, H. longistipes (dromedary), H. placei (zebu cattle) and H. contortus (sheep and goat) occurred sympatrically. The study was undertaken on hosts slaughtered at the Nouakchott abattoir, on the basis of monthly collection of worms. The environment was very unfavourable to H. placei and unfavourable to H. contortus, as intensity of infection remained low throughout the year, whereas infection in the dromedary was 10 to 20-fold higher. The survival strategies during the long, dry season were different: the surviving stages were either 4th-stage larvae in digesta (dromedaries), 4th-stage larvae either in digesta or mucosae (cattle), or 4th-stage larvae in mucosae and few adults (sheep and goats). The prolificacy of female worms, indicative of the potential to contaminate pastures, was similar for all Haemonchus spp. in the rainy season. H. longistipes behave differently during the pre-rainy season as no increase of prolificacy could be demonstrated as observed in the other species. Traits of vulvar morphology are considered as markers of ecological adaptation and were studied. The knobbed and smooth female morphs (in equal proportions) were the most frequent in H. longistipes, the knobbed morph out-numbered the other morphs in H. placei, and all 3 morphs were present in sheep and goats with the linguiform form being predominant. Genetic characterization of the 3 species was performed by means of Random Amplified Polymorphic DNA (RAPD). Three groups were obtained from analysis of these data: 1 group with individuals of H. contortus, 1 group with individuals of H. placei, and 1 group with individuals of H. longistipes. This indicated that, although the 3 species were valid, H. contortus and H. placei were more similar. Intraspecific variability was 2-fold higher in H. contortus than in the 2 other species. The ecological, morphological and genetical studies showed that H. longistipes, H. placei and H. contortus could be arranged in increasing order of variability.

Adaptation, Physiological↗
PubMed1999

Isolation of rapeseed genes expressed early and specifically during development of the male gametophyte.

A cDNA subtraction and differential hybridization strategy was used to isolate cDNAs expressed early during male gametophyte development in the important crop species Brassica napus. Three cDNAs, corresponding to genes highly and specifically expressed at the tetrad and microspore stages, are presented here. The analysis of one of them, named BnM3.4, by in situ hybridization, showed that it is expressed specifically and at a high level in the rapeseed microspore. The specificity in its profile of expression is most likely transcriptionally controlled as a similar pattern of expression was also observed in Arabidopsis thaliana plants transformed by the BnM3.4 promoter fused to the reporter GUS-coding sequence. The putative BnM3.4 promoter contains three dispersed copies of a motif described previously in the promoters of several genes expressed in the male gametophyte. The BnM3.4 gene encodes a predicted novel proline-rich protein of 23.4 kDa which may interact with cytoskeletal components or have a structural role in the cell wall.

Arabidopsis↗
PubMed2001

Ethnographic critique and technoscientific narratives: the old mole, ethical plateaux, and the governance of emergent biosocial polities.

A reading of the puzzle novel Vienna Blood, by Adrian Mathews, is juxtaposed to three ethnographic sketches of contemporary ethical plateaus or domains of ethical challenge--the challenges of informed public consent to new technologies, the seductions to do whatever is medically possible (sometimes at the expense of quality of life or the good death'). and the power of money in driving the biotechnological industries. Vienna Blood deals with precautionary germplasm modification and chemical camouflage justified as protection against ethnically-targeted biological warfare, and touches on a series of technologies such as new reproductive technologies, genetic engineering, and cryptographic attacks and defenses, as well as the ability to evade regulatory controls. Such technoscientifically informed novels are useful as cautionary tales, in exploring the complexity and interaction among new technologies, and the phantasmagoria that help drive new technologies. They are not so good at thinking through institutional development: a challenge for ethnography and new social theory. Ethnography, like novels, can function as checks on the mechanisms of abstraction and universalization that frequently bedevil the non-anthropological, non-cross-culturally or cross-temporally comparative, social sciences. Questions are raised about new or emergent biosocialities, forms of governance, and forms of cultural critique.

Advertising↗
PubMed1998

How does offspring quality change with age in male Drosophila melanogaster?

We examined the relationship of genetic quality to age in male Drosophila melanogaster to test two contrasting hypotheses. The traditional hypothesis is that older males have proven their viability and therefore produce offspring of superior genetic quality. This hypothesis is often evoked as an explanation for female preference for older mates. In contrast, we have recently argued that older fathers may produce offspring of inferior genetic quality. Here, we present results from an experiment designed to measure the genetic quality of offspring produced by 2 day old, 2 week old and 5 week old male D. melanogaster. We found a statistically significant small reduction in larval viability and a similar but statistically non-significant reduction in son mating ability among the offspring of the 5 week old males. Daughter fecundity showed no apparent trend for a reduction nor an increase in performance with increasing age of the fathers. There was no evidence of a difference between the 2 day old and the 2 week old males for any of these three fitness components. These results are in somewhat better accordance with our alternative hypothesis, but the relatively weak and late occurring effects indicate that mate choice based on age may not be a viable strategy in this population.

Aging↗
PubMed2003

Prevalence and spectrum of p53 mutations in white Hispanic and non-Hispanic women with breast cancer.

Hispanic women differ from non-Hispanics in breast cancer incidence, stage at diagnosis, and survival. Ethnic differences in genetic makeup, reproductive patterns, diet, socioeconomic status, physical activity, and other unidentified cultural factors may be responsible for the disparity. This study investigated occurrences of p53 tumor suppressor gene mutations in South Florida white Hispanic and white non-Hispanic women with primary breast cancer. Tumor tissues were obtained from a consecutive series of women with breast cancer who underwent breast resection at the Jackson Memorial Hospital, Miami, Florida between 1984 and 1986. A total of 231 women with primary breast cancer, aged 31-85 years, were included in the study. Among them, 64 (27.7%) were white Hispanic and 167 (72.3%) were white non-Hispanic. The majority of the patients were white non-Hispanics (72.3%). Compared to white non-Hispanics, however, white Hispanics had significantly higher proportions of tumors larger than 2 cm (53.1% v.s. 28.7%, p = 0.00) as well as larger tumor size at diagnosis (mean: 4.2 v.s. 3.0 cm, p = 0.00). The p53 gene mutation rate was significantly lower in white Hispanics than in white non-Hispanics (51.6% v.s. 70.7%, p = 0.01). Furthermore, among node-negative breast cancer patients, after adjustment for tumor size at diagnosis, logistic regression results showed that white Hispanics were 71% less likely than white non-Hispanics to carry p53 mutations (OR = 0.29 and 95% CI = 0.09-0.91). We conclude that white Hispanic women with breast cancer might have lower p53 gene mutation prevalence than white non-Hispanic women.

Adult↗
PubMed2004

Genomic research and data-mining technology: implications for personal privacy and informed consent.

This essay examines issues involving personal privacy and informed consent that arise at the intersection of information and communication technology (ICT) and population genomics research. I begin by briefly examining the ethical, legal, and social implications (ELSI) program requirements that were established to guide researchers working on the Human Genome Project (HGP). Next I consider a case illustration involving deCODE Genetics, a privately owned genetic company in Iceland, which raises some ethical concerns that are not clearly addressed in the current ELSI guidelines. The deCODE case also illustrates some ways in which an ICT technique known as data mining has both aided and posed special challenges for researchers working in the field of population genomics. On the one hand, data-mining tools have greatly assisted researchers in mapping the human genome and in identifying certain "disease genes" common in specific populations (which, in turn, has accelerated the process of finding cures for diseases tha affect those populations). On the other hand, this technology has significantly threatened the privacy of research subjects participating in population genomics studies, who may, unwittingly, contribute to the construction of new groups (based on arbitrary and non-obvious patterns and statistical correlations) that put those subjects at risk for discrimination and stigmatization. In the final section of this paper I examine some ways in which the use of data mining in the context of population genomics research poses a critical challenge for the principle of informed consent, which traditionally has played a central role in protecting the privacy interests of research subjects participating in epidemiological studies.

Computational Biology↗
PubMed2004

How the role of computing is driving new genetics' public policy.

In this paper we will examine some ethical aspects of the role that computers and computing increasingly play in new genetics. Our claim is that there is no new genetics without computer science. Computer science is important for the new genetics on two levels: (1) from a theoretical perspective, and (2) from the point of view of geneticists practice. With respect to (1), the new genetics is fully impregnate with concepts that are basic for computer science. Regarding (2), recent developments in the Human Genome Project (HGP) have shown that computers shape the practices of molecular genetics; an important example is the Shotgun Method's contribution to accelerating the mapping of the human genome. A new challenge to the HGP is provided by the Open Source Philosophy (I computer science), which is another way computer technologies now influence the shaping of public policy debates involving genomics.

Access to Information↗
PubMed1998

Genome vikings.

Explore the source record for details and available documents.

Chromosome Mapping↗
PubMed1998

Genetics and insurance in Britain: why more than just the Atlantic divides the English-speaking nations.

The British Government's official advisory committee on genetics has recommended a moratorium on the disclosure of genetic test results for life insurance until predictions based on such tests can be validated as actuarially important. In contrast, the trade association of the British insurance industry believes that genetic tests relating to eight conditions can yield information useful for life insurance. Although the Government has yet to respond, the debate is already moving on to genetic testing and the funding of health care for the elderly.

Advisory Committees↗