Challenging in food safety

Food safety is one of most important challenge in our countries. Indeed, adulteration and poising food are often described in newspapers. FDA and ESFA are the organisations issued to guarantee food safety in U.S and Europe, respectively. Which are the most common problems that determine food adulteration. The first cause of this kind of problem is the bacterial contamination: indeed bacteria can provoke food spoilage as well as they are pathogen in some cases.

To decrease the possibility of food spoilage, numerous testing must be performed in food processing company. The safety ideal “from farm to fork” created by FDA can be reached only through an attentive analysis of raw materials, processing and packing procedures in order to assure maximal sterility in each step. Furthermore, some laboratories are specialised in bacterial, toxin and sterility testing: the common goal is to provide consumers with safe and wholesome food at least for all shelf-life of food self. These laboratories usually offer a broad range of services and usually communicate with their clients through LIMS system. LIMS systems, indeed, are able to collect large number of data analysis, reports and general forms and rapidly make them available to clients.

Ig Nobel prize

On October 1st at Harvard’s Sanders Theatre, Ig Nobel prizes were awarded. Ig Nobel prize is awarded to improbable researches that first make scientists laugh and then make them think. As correspondent Nobel prizes, awards for different application field are assigned: from medicine to economy, from peace to literature, the most improbable researches are highlighted.

In 2009 Medicine Ig prize was awarded to dr. Unger who has studied for 60 years the role of cracking knuckles in the genesis of finger arthritis: to do this, he has cracked the knuckles of his left hand without touching his right hand for 60 years. Public Health Ig Nobel prize was awarded to an innovative kind of brasserie that can be converted in more protective face masks, as necessary. This model is U.S patent since 2007. Japanese scientists won the Ig Nobel prize for Biology: they showed how a thermophilic bacteria isolated for faeces of giant panda could reduce kitchen refuses more than 90% in mass. Last but not least, Peace prize was awarded for an experimental study about the opportunity to be smashed over head by an empty or full beer bottle: in both cases energy to break beer bottle is higher than those required to fracture human skull, so in both cases beer bottles are dangerous instruments in physical disputes. We hope to make you laugh but then you should think!

Reference: http://improbable.com/

Nanoparticles as a novel class of anti-bacterial

Anti-bacterial drug often acts by disrupting the double layer of cellular membrane that is negatively charged. These molecules contain positive groups and an hydrophobic core, important to insert into the membrane. In order to specifically overcome the blood brain barrier and reach the brain, some researchers of the University of Singapore studied a novel particle constituting of an hydrophobic core and a strain of positively charged arginine. Tat sequence, derived from HIV virus, was used to vehicle the molecule over the blood brain barrier because TAT protein mediates the passage of proteins across the endothelial cells.

Furthermore, cholesterol was added to increase the capability to penetrate into the membrane and to concentrate the active peptide. So, the final structure of this peptide nanoparticle is Cholesterol- 3 glycine, as a spacer- 6 arginine- TAT protein. In vitro, this peptide killed fungi, bacteria and yeast and showed an important activity also in vivo in rabbit infected with S. Aureus, meningitis’s vector, by overcoming the blood brain barrier. This study opens new perspectives on nanoparticle engineering that could be applied in a broad range of diseases: for instance in cancer or in other situation in which is crucial to target a specific type of cells.

Comparison between Baculovirus and E. Coli, as expression system

Baculovirus expression system is commonly used for protein expression, in particular it is used for eukaryotic proteins that cannot be correctly folded in E. Coli. This virus, not infectious for human, infect insect cells, such as Sf9, Sf21 or Hi5, and are isolated to performed high amount of recombinant proteins. Indeed, Baculovirus genome could be easily modified with current molecular biology techniques –molecular cloning, following by recombination and transposition- and propagated in normal cellular biology lab, not P2 or P3 chambers are necessary to use this virus. It’s possible to insert long fragment of exogenous DNA into virus genome, this aspect is important and represent a good advantages in respect of E. Coli because eukaryotic proteins are usually codified by long genes.

Another significant advantage is the capability to introduce post-translational modifications, such as phosphorylation, glycosilation that are necessary to obtain the complete functionality of the recombinant protein. Thus, proteins produced with this system could be employed for instance in biochemical assays, after purification, and in screening of pharmacological compounds. By contrast, the main disadvantages associated with Baculovirus are the cost and the yield: insect cells culture is more expensive than E. Coli culture, because of the media, sera and molecular reagents necessary to make the transfection. Furthermore, the yield is lower and if 1 mg of recombinant protein can be produced form 1 litre of E. Coli culture, much more litres of insect cells are necessary to produce the same amount of protein.
What are the parameters important to choose one type of expression system in respect of another one? Firstly, it has to be known very well the protein that has to be produced: literature review gives interesting suggestions and the most common expression system is usually the best one. Secondarily, the aim of the study is important, indeed if a functional study has to be performed, it’s crucial to have an active protein also in a little amount, by contrast for crystallization study is important to consider that milligrams of protein have to be purified. Finally, both Baculovirus and E. Coli are tool easy to use, but in the case of Baculovirus some experience in cellular biology rather than biochemistry is important. The timing has also to be considered because Baculovirus-insect cell system requires at least one month, after cloning, to perform first infections; by contrast, E. Coli needs only cloning procedures to express the protein of interest. Both recombinant viruses and bacteria can be frozen, in order to have reagents ready to use, it’s important keep sterility and a great classification if numerous proteins are studied at the same time in the lab: special software are commercially available for this purpose. In conclusion, both techniques are useful in biochemistry, structural biology and molecular biology and in respect of the aim of the study is crucial to choose the more convenient one.