Lactoferrin Inhibition of the Complex Formation between ACE2 Receptor and SARS CoV-2 Recognition Binding Domain.

The present investigation focuses on the analysis of the interactions among human lactoferrin (LF), SARS-CoV-2 receptor-binding domain (RBD) and human angiotensin-converting enzyme 2 (ACE2) receptor in order to assess possible mutual interactions that could provide a molecular basis of the reported preventative effect of lactoferrin against CoV-2 infection. In particular, kinetic and thermodynamic parameters for the pairwise interactions among the three proteins were measured via two independent techniques, biolayer interferometry and latex nanoparticle-enhanced turbidimetry. The results obtained clearly indicate that LF is able to bind the ACE2 receptor ectodomain with significantly high affinity, whereas no binding to the RBD was observed up to the maximum "physiological" lactoferrin concentration range. Lactoferrin, above 1 µM concentration, thus appears to directly interfere with RBD-ACE2 binding, bringing about a measurable, up to 300-fold increase of the KD value relative to RBD-ACE2 complex formation.

The bulb retouchers in the Levant: New insights into Middle Palaeolithic retouching techniques and mobile tool-kit composition.

In this paper we describe two assemblages of flint retouchers or "bulb retouchers" retrieved from Nesher Ramla and Quneitra, two Middle Palaeolithic, open-air sites in the Levant. The site of Nesher Ramla yielded the largest assemblage of bulb retouchers (n = 159) currently known, allowing a detailed investigation of this poorly known phenomenon. An extensive experimental program and use-wear analysis enabled us to characterize the different sets of traces related to the retouching activity and to identify different motions applied by the knappers in the course of this action. In both sites, blanks used as bulb retouchers were almost exclusively retouched items, with a special emphasis on convergent morphotypes in Nesher Ramla. The use of retouched items as bulb retouchers is a common trait over different time spans and geographical areas. Our data suggests that bulb retouchers were versatile, multi-purpose tools with a long use-life, transported over long distances as components of the hunter-gatherer mobile tool kit. The high frequencies of bulb retouchers within some archaeological units of Nesher Ramla appear to be connected to the highly curated nature of the lithic assemblages, in turn reflecting a high mobility of the human groups that produced them.