Lanthanide induced shift as a tool for isomer assignment in esters of unsaturated fatty acids

Addition of Yb(fod)₃ to methyl oleate (cis) and methyl elaidate (trans) shifts the carboxylic lines of their ¹³C-NMR spectra to different extents; that of the cis isomer less than that of the trans isomer, as is to be expected.

On the same theoretical ground it can be anticipated that the opposite will occur for C-17: an effect that has been confirmed experimentally. The method is thus proposed as a means of aiding in the assignment of the cis and trans configuration in esters of fatty acids with one double bond.     

Structural basis of light chain amyloidogenicity: comparison of the thermodynamic properties, fibrillogenic potential and tertiary structural features of four Vlambda6 proteins

Primary (AL) amyloidosis results from the pathologic deposition of monoclonal light chains as amyloid fibrils. Studies of recombinant-derived variable region (VL) fragments of these proteins have shown an inverse relationship between thermodynamic stability and fibrillogenic potential. Further, ionic interactions within the VL domain were predicted to influence the kinetics of light chain fibrillogenicity, as evidenced from our analyses of a relatively stable Vlambda6 protein (Jto) with a long range electrostatic interaction between Asp and Arg side chains at position 29 and 68, respectively, and an unstable, highly fibrillogenic Vlambda6 protein (Wil) that had neutral amino acids at these locations. To test this hypothesis, we have generated two Jto-related mutants designed to disrupt the interaction between Asp 29 and Arg 68 (JtoD29A and JtoR68S). Although the thermodynamic stabilities of unfolding for these two molecules were identical, they exhibited very different kinetics of fibril formation: the rate of JtoD29A fibrillogenesis was slow and comparable to the parent molecule, whereas that of JtoR68S was significantly faster. High-resolution X-ray diffraction analyses of crystals prepared from the two mutants having the same space group and unit cell dimensions revealed no significant main-chain conformational changes. However, several notable side-chain alterations were observed in JtoR68S, as compared with JtoD29A, that resulted in the solvent exposure of a greater hydrophobic surface and modifications in the electrostatic potential surface. We posit that these differences contributed to the enhanced fibrillogenic potential of the Arg 68 mutant, since both Jto mutants lacked the intrachain ionic interaction and were equivalently unstable. The information gleaned from our studies has provided insight into structural parameters that in addition to overall thermodynamic stability, contribute to the fibril forming propensity of immunoglobulin light chains.     

Antigen binding and solubility effects upon the veneering of a camel VHH in framework-2 to mimic a VH

Heavy chain only antibodies of camelids bind their antigens with a single domain, the VHH, which acquired adaptations relative to classical VHs to function in the absence of a VL partner. Additional CDR loop conformations, outside the canonical loop structures of VHs, broaden the repertoire of the antigen-binding site. The combined effects of part of the CDR3 that folds over the "former" VL binding site and framework-2 mutations to more hydrophilic amino acids, enhance the solubility of VHH domains and prevent VL pairing. cAbAn33, a VHH domain specific for the carbohydrate moiety of the variant surface glycoprotein of trypanosomes, has a short CDR3 loop that does not cover the former VL binding site as well as a VH-specific Trp47 instead of the VHH-specific Gly47. Resurfacing its framework-2 region (mutations Tyr37Val, Glu44Gly and Arg45Leu) to mimic that of a human VH restores the VL binding capacity. In solution, the humanised VHH behaves as a soluble, monomeric entity, albeit with reduced thermodynamic stability and affinity for its antigen. Comparison of the crystal structures of cAbAn33 and its humanised derivative reveals steric hindrance exerted by VHH-specific residues Tyr37 and Arg45 that prevent the VL domain pairing, whereas Glu44 and Arg45 are key elements to avoid insolubility of the domain.     

Mycoplasma hyopneumoniae temporal trends of infection and pathological effects in wild boar populations

Mycoplasma hyopneumoniae (Mhyo) is the principal etiological agent of enzootic pneumonia (EP), one of the most economically important diseases in the pig production industry worldwide. Although swine and wild boars (Sus scrofa) share susceptibility to Mhyo infection, information regarding the dynamics of Mhyo infections and pathology in wild boars is currently limited. Therefore, the aim of this study was to determine the spatiotemporal dynamics of Mhyo infections in free-living wild boars through serological ELISA testing. Additionally, the presence of EP-like gross lesions and their association with the presence of Mhyo, based on a PCR assay, were assessed. Over a period of 5 years, antibodies against Mhyo were detected in 655 (30.0 %) of the 2,177 analyzed wild boars. A generalized temporal increase of seroprevalence coupled with an increase of mean antibody titers of seropositive individuals was found. Moreover, a similar seroprevalence between age classes associated with higher antibody titers of younger individuals indicated the wild boars were infected during the early stages of their life. Out of 99 lungs tested, 43 showed EP-like lesions and 45 were PCR positive for the presence of Mhyo DNA. The lung lesion scores were related to the sex and age of the wild boars, with young individuals having higher lung scores than others, and there was a positive association with the Mhyo PCR-positive status. The temporal increase of the Mhyo seroprevalence and infection association with EP-like lesions, when coupled with the spreading of wild boar populations, raises concerns on the epidemiological role of this species.     

Protura of Italy, with a key to species and their distribution

The Italian Protura were studied basing on 5103 specimens from 198 sampling areas, along with bibliographic data from 49 collecting sites. 17 out of the 20 Italian regions are covered. As a result, 40 species have been identified (belonging to 8 genera and 4 families), 6 of which are new records for the Italian fauna.A key to the Italian species is reported, followed by a series of distribution maps and brief remarks for some of them. A preliminary biogeographical overview allowed us to delineate the chorological categories of these species, 10 of which are actually known only in Italy. The comparison with the species richness known for some best studied Central and Eastern European Countries leads us to speculate that widening our research, Italian Protura check-list will be much implemented.