Functional properties of purified vicilins from cowpea (Vigna unguiculata) and pea (Pisum sativum) and cowpea protein isolate

The major storage globulins (vicilins) of cowpea (Vigna unguiculata) and pea (Pisum sativum) seeds were purified by ammonium sulfate precipitation, and a semipurified cowpea protein isolate (CPI) was prepared by isoelectric precipitation. Some of the functional properties of these proteins, including solubility, foaming, and emulsifying capacities, were investigated and compared. The solubility of purified cowpea vicilin was reduced at pH 5.0, increasing markedly below and above this value. Pea vicilin exhibited poor solubility between pH 5.0 and pH 6.0, and CPI was little soluble in the pH range from 4.0 to 6.0. At neutral pH, the emulsifying activity indexes (EAI) of purified pea vicilin and CPI were 194 and 291 m(2)/g, respectively, which compare quite favorably to EAIs of 110 and 133 m(2)/g for casein and albumin, respectively. Remarkably, purified cowpea vicilin exhibited an EAI of 490 m(2)/g, indicating a very high emulsifying activity. Purified cowpea and pea vicilins exhibited lower foaming capacities and foam stablity indexes (FSI) than CPI. FSI values of 80 and 260 min were obtained for purified pea and cowpea vicilin, respectively, whereas a FSI value of 380 min was obtained for CPI. These results are discussed in terms of the possible utilization of purified vicilins or protein isolates from pea and cowpea in the food processing industry.     

Molecular structure of DNA by scanning tunneling microscopy

Uncoated DNA molecules marked with an activated tris(l-aziridinyl) phosphine oxide (TAPO) solution were deposited on gold substrates and imaged in air with the use of a high-resolution scanning tunneling microscope (STM). Constant-current and gap-modulated STM images show clear evidence of the helicity of the DNA structure: pitch periodicity ranges from 25 to 35 angstroms, whereas the average diameter is 20 angstroms. Molecular structure within a single helix turn was also observed.     

A relevant long-term impact of the circulation of a potentially contaminated vaccine on the distribution of scrapie in Italy. Results from a retrospective cohort study

ABSTRACT: A sudden increase in the incidence of scrapie in Italy in 1997 was subsequently linked to theuse of a potentially infected vaccine against contagious agalactia. The relative risk for theexposed farms ranged between 6 and 40. The aim of this study was to assess the long-termimpact of exposure to the potentially scrapie-contaminated vaccine on the Italian classicalscrapie epidemic. We carried out a retrospective cohort study, fitting mixed-effects Poissonregression models, dividing national geographic areas into exposure categories on the basis ofthe vaccine circulation levels. We took into account the sensitivity of the surveillance systemapplied in the different areas. The population attributable fraction (PAF) was used to assessthe impact on the total population of farms associated with the effect of circulation of thevaccine. The provinces where the vaccine was more often sold were noted to have a higherlevel of disease when compared to those provinces where the vaccine was sold less often(incidence rate ratio [IRR]: 2.7; 95% confidence interval [CI]: 1.1-6.5). The populationattributable fraction was high (68.4%). Standardization techniques allowed to account for thepotential of geographical variability in the sensitivity of the Italian surveillance system.Although the number of the directly exposed farms was limited, an important long-termimpact of the vaccine circulation could be quantified in terms of secondary outbreaks likelydue to the exchange of animals from directly exposed flocks.