An early representation of a gorilla from fifteenth-century Central Asia

Primates - The present work describes the earliest known image of a gorilla (Gorilla sp.) to appear outside Africa. This is found in an Asian miniature painted on silk from the second half of the...     

Evaluation of chiroptical properties of molecules by asymmetric photochemistry

The physics involved in photochemistry with circularly polarized light, the warnings on its inherent limitations, as well as some examples of application on organic molecules are briefly reviewed.     

The Csk-binding protein PAG regulates PDGF-induced Src mitogenic signaling via GM1

Spatial regulation is an important feature of signal specificity elicited by cytoplasmic tyrosine kinases of the Src family (SRC family protein tyrosine kinases [SFK]). Cholesterol-enriched membrane domains, such as caveolae, regulate association of SFK with the platelet-derived growth factor receptor (PDGFR), which is needed for kinase activation and mitogenic signaling. PAG, a ubiquitously expressed member of the transmembrane adaptor protein family, is known to negatively regulate SFK signaling though binding to Csk. We report that PAG modulates PDGFR levels in caveolae and SFK mitogenic signaling through a Csk-independent mechanism. Regulation of SFK mitogenic activity by PAG requires the first N-terminal 97 aa (PAG-N), which include the extracellular and transmembrane domains, palmitoylation sites, and a short cytoplasmic sequence. We also show that PAG-N increases ganglioside GM1 levels at the cell surface and, thus, displaces PDGFR from caveolae, a process that requires the ganglioside-specific sialidase Neu-3. In conclusion, PAG regulates PDGFR membrane partitioning and SFK mitogenic signaling by modulating GM1 levels within caveolae independently from Csk.     

Activity and conformational changes of alpha-chymotrypsin in reverse micelles studied by spin labeling.

alpha-Chymotrypsin (CT), spin-labeled at the active site by using an acylating label which constitutes a substrate for this protein, has been investigated in reverse micelles formed by AOT in isooctane. The electron spin resonance spectra provided information on conformation, dynamics and deacylation activity. The dynamics of the label bound to CT appears to be more hindered in reverse micelles than in aqueous solution, probably owing to the effect of the micellar environment on protein conformation. The deacylation rate in reverse micelles does not show the characteristic bell-shaped dependence on water content which is generally found for CT enzymatic activity.     

Synthesis,Chiroptical Properties and Density Functional Theory Calculations of 3,3’‐Biphenyl‐2,2’‐BiTropone

The synthesis of new bitropone derivatives, namely, 3,3'‐biphenyl‐2,2'‐bitropone and 7,7’‐biphenyl‐2,2'‐bitropone, are reported. Isolation of enantiomers arising from restricted rotation around the C‐C bond connecting the tropone moieties was attempted by means of chiral high performance liquid chromatography (HPLC). No separation was obtained for 7,7’‐biphenyl‐2,2'‐bitropone. For 3,3'‐biphenyl‐2,2'‐bitropone, difficulties were encountered because of the low separation factor of the peaks and the presence of a rapid racemization process. However, quantitative chiroptical data on the antipodes were obtained by linking a circular dichroism (CD) spectrometer and a UV–vis spectrophotometric detector in series to the HPLC instrument. The analysis of the CD and UV–vis spectra in terms of absolute conformations was done with the help of theoretical calculations performed at the Density Functional Theory (DFT) level. The most stable conformations of the 3,3'‐biphenyl‐2,2'‐bitropone in its ground state were obtained. Starting from these minimum energy conformations, it was possible to compute theoretical CD and UV absorption spectra that fit well with the experimental ones. From this comparison the absolute configuration to the antipodes was assigned. Finally, the effect of the presence of the two lateral phenyl substituents on the structure of the bitropone and hence on the CD spectrum is discussed. Chirality 25:648–655, 2013. © 2013 Wiley Periodicals, Inc.     

The concept of species and the foundations of biology, a case study: the Callithrix jacchus group (Primates-Platyrrhini).

The axiomatic theory presented in Galleni and Forti [1999], being part of the foundational programme of Ennio De Giorgi, is based on the fundamental notions of quality, relation, operation and collection, and provides a very general axiomatization of the biological notions of living object, generation, species and speciation. Within this theoretical framework we consider here a difficult case of classification of species: the Callithrix jacchus group of the New World monkeys. Although the morphological analysis strongly suggests the individuation of six different species, nevertheless several experiments of crossing give evidence to fertility of hybrids. Since both the morphological and the hybridological criteria have shown to be of enormous importance in actual classification of species, this apparent contradiction seems very disappointing. Our axiomatization of speciation processes as operations acting in special time intervals permits to avoid the contradiction by allowing for individuals which, during such special periods, may belong to more than one species. Therefore we assume that one or more speciation processes are developing, starting from a unique protospecies and differentiating in six new ones. In order to obtain more evidence of these processes, new observations and suitable experiments are needed.