The uncoupling protein from brown-adipose-tissue mitochondria. Chymotrypsin-induced structural and functional modifications

Mitoplasts prepared from brown adipose tissue mitochondria were treated with chymotrypsin and the fragments derived from the 32-kDa uncoupling protein identified by immunoblotting. Extensive proteolysis of the uncoupling protein occurred, the polypeptide pattern being affected by binding of the inhibitory nucleotide GDP. Chymotrypsin modifies the nucleotide binding site, lowering its affinity from 1.7 microM to 21 microM but without decreasing its binding capacity. Nucleotide bound to the modified site can still inhibit the permeation of H+ and Cl- through the protein. The ion conducting pathway itself is also sensitive to chymotrypsin, Cl- and H+ transport being partially inhibited in parallel. The ability of fatty acids to increase the H+ permeability of the protein is also inhibited in parallel with the basal H+ permeability. The results confirm that the transport of H+ and Cl-, and the fatty acid regulation of H+ permeation all share a common structural element within the 32-kDa protein.     

Meningeal arteries in rhesus macaques (Macaca mulatta): implications for vascular evolution in anthropoids.

The branching patterns of meningeal arteries are reported for 200 endocast hemispheres representing rhesus monkeys (Macaca mulatta) of known cranial capacity. We detect five basic patterns for the branching of the anterior division of the middle meningeal artery and its relationship with the anterior meningeal artery. These results confirm and elaborate trends published for much smaller samples that were based on direct dissections of rhesus monkey arterial patterns. The most common pattern is that in which the anterior meningeal artery dominates the blood supply above the rostral part of the middle cranial fossa. Analysis of cranial capacities reveals that presence of this pattern on both sides of endocasts is associated with increased cranial capacity. When studied in light of published reports of anatomical dissections of cranial arteries in apes and human embryological data, the anterior meningeal artery in rhesus monkeys appears to be a possible homologue of the lacrimal meningeal artery in apes and the anterior branch of the middle meningeal artery in humans. This finding provides a step towards understanding cranial vasculature homologies that may be useful for accurately scoring the branching patterns of the meningeal arteries in monkeys, apes, and humans.     

The evolution of myrmicine ants: phylogeny and biogeography of a hyperdiverse ant clade (Hymenoptera: Formicidae)

This study investigates the evolutionary history of a hyperdiverse clade, the ant subfamily Myrmicinae (Hymenoptera: Formicidae), based on analyses of a data matrix comprising 251 species and 11 nuclear gene fragments. Under both maximum likelihood and Bayesian methods of inference, we recover a robust phylogeny that reveals six major clades of Myrmicinae, here treated as newly defined tribes and occurring as a pectinate series: Myrmicini, Pogonomyrmecini trib.n. , Stenammini, Solenopsidini, Attini and Crematogastrini. Because we condense the former 25 myrmicine tribes into a new six‐tribe scheme, membership in some tribes is now notably different, especially regarding Attini. We demonstrate that the monotypic genus Ankylomyrma is neither in the Myrmicinae nor even a member of the more inclusive formicoid clade—rather it is a poneroid ant, sister to the genus Tatuidris (Agroecomyrmecinae). Several species‐rich myrmicine genera are shown to be nonmonophyletic, including Pogonomyrmex, Aphaenogaster, Messor, Monomorium, Pheidole, Temnothorax and Tetramorium. We propose a number of generic synonymies to partially alleviate these problems (senior synonym listed first): Pheidole = Anisopheidole syn.n. = Machomyrma syn.n. ; Temnothorax = Chalepoxenus syn.n. = Myrmoxenus syn.n. = Protomognathus syn.n. ; Tetramorium = Rhoptromyrmex syn.n. = Anergates syn.n. = Teleutomyrmex syn.n. The genus Veromessor stat.r. is resurrected for the New World species previously placed in Messor; Syllophopsis stat.r. is resurrected from synonymy under Monomorium to contain the species in the hildebrandti group; Trichomyrmex stat.r. is resurrected from synonymy under Monomorium to contain the species in the scabriceps‐ and destructor‐groups; and the monotypic genus Epelysidris stat.r. is reinstated for Monomorium brocha. Bayesian divergence dating indicates that the crown group Myrmicinae originated about 98.6 Ma (95% highest probability density 87.9–109.6 Ma) but the six major clades are considerably younger, with age estimates ranging from 52.3 to 71.1 Ma. Although these and other suprageneric taxa arose mostly in the middle Eocene or earlier, a number of prominent, species‐rich genera, such as Pheidole, Cephalotes, Strumigenys, Crematogaster and Tetramorium, have estimated crown group origins in the late Eocene or Oligocene. Most myrmicine species diversity resides in the two sister clades, Attini and Crematogastrini, which are estimated to have originated and diversified extensively in the Neotropics and Paleotropics, respectively. The newly circumscribed Myrmicini is Holarctic in distribution, and ancestral range estimation suggests a Nearctic origin. The Pogonomyrmecini and Solenopsidini are reconstructed as being Neotropical in origin, but they have subsequently colonized the Nearctic region (Pogonomyrmecini) and many parts of the Old World as well as the Nearctic region (Solenopsidini), respectively. The Stenammini have flourished primarily in the northern hemisphere, and are most likely of Nearctic origin, but selected lineages have dispersed to the northern Neotropics and the Paleotropics. Thus the evolutionary history of the Myrmicinae has played out on a global stage over the last 100 Ma, with no single region being the principal generator of species diversity. This published work has been registered in ZooBank, http://zoobank.org/urn:lsid:zoobank.org:pub: BB6829C4‐DA79‐45FE‐979E‐9749E237590E .     

Effect of ionophores on carrier-mediated electron translocation in ferricyanide-containing liposomes

Ferricyanide-containing liposomes were used as a system to compare the electron- and proton-translocating properties of six redox reagents commonly used as electron donors for biochemical systems. The effects of different ionophore combinations on the ferricyanide-reduction rate were generally consistent with the expected proton- and electron-translocating properties of the mediators. The transmembrane pH gradient produced by hydrogen carriers was demonstrated. Nigericin or valinomycin plus carbonyl cyanide p-trifluoromethoxyphenylhydrazone are capable of collapsing this gradient and of stimulating ferricyanide reduction mediated by this type of carrier. No pH gradient is produced with the electron carrier 1,1'-dibutylferrocene. In the presence of tetraphenylboron anion, which is needed for this carrier to act as an efficient mediator, addition of valinomycin alone is sufficient to obtain full stimulation of ferricyanide reduction. NNN'N'-Tetramethyl-p-phenylenediamine does not behave as a simple electron carrier. During NNN'N'-tetramethyl-p-phenylenediamine-mediated ferricyanide reduction protons are translocated across the membrane and accumulated in the vesicles. This is not due to the presence of demethylated impurities in the NNN'N'-tetramethyl-p-phenylenediamine sample, but may be the result of an accumulation of oxidation products other than the Wurster's Blue radical. These results suggest a reconsideration of studies on protonmotive forces across membranes where NNN'N'-tetramethyl-p-phenylenediamine is used as a mediator.