Blind population genetics survey of tropical rainforest trees

Rainforest tree species can be difficult to identify outside of their period of reproduction. Vascular tissues from Carapa spp. individuals were collected during a short field trip in French Guiana and analysed in the laboratory with nuclear and chloroplast markers. Using a Bayesian approach, > 90% of the samples could be assigned to one of two distinct clusters corresponding to previously described species, making it possible to estimate the genetic structure of each species and to identify cases of introgression. We argue that this blind procedure represents a first-choice rather than a fallback option whenever related taxa are investigated.     

Social responsibility in human genetics – a survey

The potential for molecular biological manipulation of human beings is a challenge to the social responsibility of human geneticists. The concept of individual healthcare is compromised by a reductionist approach to human biology which defines health solely in terms of genetics. The ability of professionals working in the fields of molecular biology and human genetics to understand the wider social context of their work and the effects it may have on individual health is rarely discussed. This is a report of a survey of social attitudes and awareness carried out among molecular biologists and human geneticists in Germany. The results reveal differences in the understanding of health and these perceptions are shown to depend on the age and gender of the professionals involved.     

The economics of clinical genetics services. II. A time analysis of a medical genetics clinic.

In a time-and-reimbursement analysis of our clinical genetics service, we documented (1) the time spent by professionals and staff in serving families before, during, and after the clinic visit; (2) the charges and reimbursement for the services provided; and (3) the relationship between income from clinical practice and the personnel costs of the clinic. We found that newly referred and returning families required 7.1 and 4.0 h, respectively. Average collections for professional services were +135 (+19/h) for new families and +49 (+12/h) for returning families. Income from clinical practice covered 37% of the clinical portion of personnel costs. These results indicate that cognitive clinical genetics services are labor intensive, yield low payments per service hour, and are not financially self-supporting. To improve the economic status of genetics clinics, administrators might consider rendering services more efficiently; increasing charges for services; billing for all services provided to all family members; billing for all genetics professionals, including counselors and social workers; and requesting payment at the time of service.     

A dynamical model for a co-operative enzyme.

Proteins partially immersed in the hydrophobic portion of a lipid bilayer interact by means of London-van der Waals non-bonding dispersion forces. Moreover, in certain organelles, enzymes are structured in a lattice or ordered matrix. These conditions may facilitate the establishment of long-range correlations between proteins. We studied the dynamical properties of a model for an enzyme endowed with a highly co-operative conformational transition between two reactive states. Two cases were considered, a closed system and an open system. In the closed system for different degrees of interaction among the proteins, it was found that for a substrate concentration greater than a certain threshold an abrupt change of enzymatic activity occurs. This biphasic behavior has been observed in the enzymatic activity of crystalline mitochondrial aspartate aminotransferase and for some other crystalline enzymes. In the analysis of the open system, for a specific input rate of the substrate, two different dynamics were found depending on the selected degree of interaction. For a certain value of a parameter phi, representing the degree of interaction among the reacting units, three steady states co-exist. This multiplicity confers excitable properties to the model. For larger values of phi, limit cycle type solutions were obtained. Thus, a sustained oscillatory product formation of the enzymatic reaction is observed. These results are compared with experimental observations of enzyme extracts detected by NMR.