Asymmetric inhibition by phlorizin of halide movements across the red blood cell membrane

Using human red cell ghosts, it was shown that external phlorizin inhibits Cl⁻ and I⁻ equilibrium exchange. Internal phlorizin has little effect on I⁻ exchange and no detectable effect on Cl⁻ exchange. This asymmetry is similar to that observed with the much more slowly exchanging SO₄²⁻ and different from that of sugars like l-arabinose or d-xylose which are inhibited by phlorizin from either surface.     

How intelligent is a cephalopod? Lessons from comparative cognition

The soft-bodied cephalopods including octopus, cuttlefish, and squid are broadly considered to be the most cognitively advanced group of invertebrates. Previous research has demonstrated that these large-brained molluscs possess a suite of cognitive attributes that are comparable to those found in some vertebrates, including highly developed perception, learning, and memory abilities. Cephalopods are also renowned for performing sophisticated feats of flexible behaviour, which have led to claims of complex cognition such as causal reasoning, future planning, and mental attribution. Hypotheses to explain why complex cognition might have emerged in cephalopods suggest that a combination of predation, foraging, and competitive pressures are likely to have driven cognitive complexity in this group of animals. Currently, it is difficult to gauge the extent to which cephalopod behaviours are underpinned by complex cognition because many of the recent claims are largely based on anecdotal evidence. In this review, we provide a general overview of cephalopod cognition with a particular focus on the cognitive attributes that are thought to be prerequisites for more complex cognitive abilities. We then discuss different types of behavioural flexibility exhibited by cephalopods and, using examples from other taxa, highlight that behavioural flexibility could be explained by putatively simpler mechanisms. Consequently, behavioural flexibility should not be used as evidence of complex cognition. Fortunately, the field of comparative cognition centres on designing methods to pinpoint the underlying mechanisms that drive behaviours. To illustrate the utility of the methods developed in comparative cognition research, we provide a series of experimental designs aimed at distinguishing between complex cognition and simpler alternative explanations. Finally, we discuss the advantages of using cephalopods to develop a more comprehensive reconstruction of cognitive evolution.     

Végétation et Flore des Monts Nimba

Conclusions Malgré ses enclaves de savance et la prairie, riches en espèces tropicales xérophiles, le territoire étudié appartient incontestablement au domaine forestier guineo-équatorial. Plusieurs climax, tous forestiers, appartenant, suivant les conditions locales, aux ordres des Triplochitetalia, Lophiretalia et Parinarietalia, y sont représentés. En fait, cette végétation primitive est profondément dégradée, aux basses altitudes par les défrichements, et sur les crêtes par les feux. C'est dire tout l'intérêt que présente, dans ce territoire, la protection de la Nature; la mise en réserve naturelle intégrale du massif du Nimba, promulguée en juillet 1944 sur l'initiative de M. le Professeur Heim et de M. le Professeur Monod, Directeur de l'Institut Français d'Afrique Noire, préservera de la destruction les richesses botaniques de cette région montagneuse.Reçue par la rédaction le 10-XI-1950.     

État actuel des recherches sur la végétation de l'afrique intertropicale française

Sans résuméReçue par la rédaction le 18-X-1949.     

A Fast Method to Estimate Kinetic Constants for Enzyme Inhibitors

We present a method to determine the reaction type and kinetic constants for enzyme inhibitors that decreases the number of experimental assays by at least a factor of five. It is based on a new theoretical formalism in terms of concentrations that dismisses the requirement of estimating initial velocities. Expressions for the time evolution of the concentrations of all the reactants are also given.