Genes and generalizations: Darden's strategies and the question of context

In her recent book Lindley Darden has endeavored to reclaim for philosophy an active role in the elaboration of good science. She has done this, not by holding up some set of rational standards derived from outside of scientific practice, but rather by delving into the history of science and coming out with a set of scientific strategies. Unconcerned about whether any particular strategy wasin fact employed in a given historical case her project depends upon two claims, first that these strategiescould have been successfully deployed in the particular cases from which they were construed, and second and more importantly, that these strategies can be generalized beyond any particular context and be put to future use. It will be argued that Darden's conception of the possible context independence of scientific strategies is based upon an overly cognitivist misconstrual. An alternative account of the relationship of context dependent and context independent aspects of scientific theory formation will be offered as well as its implications for philosophy.     

The uses of computer-aided signal peptide selection and polymerase chain reaction in gene construction and expression of secreted proteins

The computer program, SIGSEQ2, was used to select heterologous signal peptides from a catalog of published sequences to express the echistatin gene in insect (Sf9) cells. S-values for each amino acid were determined to select empirically the site of cleavage between the signal peptide and mature echistatin. Five gene fragments encoding the signal peptides for human immunoglobulin kappa (Ig kappa), Drosophila 68C glue, antistasin, bovine growth hormone (bGH), and human apolipoprotein E (Apo E) were constructed by the use of long synthetic oligonucleotides or polymerase chain reaction (PCR). Echistatin expression vectors then were constructed using the baculovirus polyhedrin promoter. Following transient transfection, the media were assayed for echistatin activity. The results indicate that the computer program greatly facilitated the selection and design of five different signal peptides and accurately predicted their relative functionality in the expression and secretion of echistatin in insect cell cultures.     

Impact of initial explants on in vitro propagation of native potato (Solanum tuberosum,Andigena group)

Plant Cell, Tissue and Organ Culture (PCTOC) - The high nutritional potential of native potatoes makes them an invaluable genetic resource for breeding. However, pathogens have caused both yield...     

Detection of Coxiella burnetii DNA in inhalable airborne dust samples from goat farms after mandatory culling

Coxiella burnetii is thought to infect humans primarily via airborne transmission. However, air measurements of C. burnetii are sparse. We detected C. burnetii DNA in inhalable and PM10 (particulate matter with an aerodynamic size of 10 μm or less) dust samples collected at three affected goat farms, demonstrating that low levels of C. burnetii DNA are present in inhalable size fractions.     

Effects of Endotoxin Contaminated FSH-preparations in Heifers

Superovulation is one important step in embryo transfer. By administration of gonadotropins a multiple ovulation is induced. Several FSH-preparations for superovulation are commercially available. Most of these consist of extracts from pituitary glands from slaughtered farm animals. According to some studies (Yagoda et al. 1990a,b), drugs can easily be contaminated with endotoxins. Endotoxins are commonly found in the environment, for example in water and silage, and in medical preparations (Yagoda et al. 1990b). Endotoxins can have several effects on animals and on human beings. They can cause endotoxaemia with effects like fever, ruminai stasis, release of prostaglandins, leukopenia and decrease of the plasma levels of calcium, zinc, iron and bile acids (Aiumlamai 1991). The severity and range of the effects caused by endotoxin are very dose-dependent. Animals receiving a low dose of endotoxin may not show the clinical signs of endotoxaemia, but can still have subclinical changes like leukopenia, prostaglandin release, mild hypocalcaemia and decreases in the plasma levels of zinc and iron (Yagoda et al. 1990b, Kindahl & Aiumlamai 1991). For humans, 5 EU/kg bodyweight is considered to be the threshold dose for appearance of clinical effects. (Anon. 1987).