Protein sequence evidence for monophyly of the carnivore families Procyonidae and Mustelidae

The amino acid sequence of the eye lens protein alpha-crystallin A of the ring-tailed cat, Bassariscus astutus, has been determined. The sequence of the Bassariscus alpha A chain, which is 173 residues long, was compared with the previously determined set of 41 mammalian alpha A sequences. Among the investigated carnivores (dog, cat, sloth bear, American mink, gray seal, and California sea lion) the Bassariscus alpha A sequence exclusively shares two amino acid replacements with the alpha A chain of the mink, Mustela vison: 7 His----Gln and 61 Ile--- -Val. The Mustela and Bassariscus alpha A sequences differ at only three positions and have no replacements in common with any of the other investigated carnivore alpha A chains. Furthermore, the replacement 7 His----Gln has only been found in three-toed sloth, whereas 61 Ile----Val occurs scattered in three other taxa: pig, rhinoceros, and prosimians. It thus is most parsimonious to join Bassariscus and Mustela--and consequently their respective families, Procyonidae and Mustelidae--as sister groups in the phylogenetic tree of mammalian alpha A sequences.      

Immunofluorescence studies of neurofilaments in the rat and human peripheral and central nervous system

Localization of antisera to neurofilament antigens derived from rat peripheral nerve was carried out in tissues of rat and human peripheral and central nervous systems by indirect immunofluorescence. Unfixed and chloroform-methanol-fixed frozen sections of tissues were incubated in purified IgG of the experimental rabbit antisera and subsequently exposed to goat anti-rabbit IgG conjugated with fluorescein isothiocyanate. Control studies were conducted on identical tissue preparations incubated in the same concentrations of nonspecific rabbit IgG or in experimental rabbit IgG absorbed with extracts of rat peripheral nerve containing neurofilament antigen. Extensive immunofluorescence was observed in rat and human peripheral and central nervous systems. The distribution and configuration of immunofluorescence corresponded to neurofilament-rich structural components of these tissues. Prominent immunofluorescence was also noted in neuronal cell bodies of spinal sensory ganglia, especially in perikarya of the large neuronal type. Immunofluorescence of the central nervous system was located predominantly in myelinated axons of the white matter in cerebrum, cerebellum, brain stem, and spinal cord. Less intense immunofluorescence was also seen in neuronal perikarya and in short thin linear processes of grey matter.     

A portrait of the adenosine triphosphate synthetase-hydrolase

It is proposed that the ATP-synthetic and ATP-hydrolytic activities of energy-transducing mitochondria, chloroplasts and bacterial membranes are due to different enzyme systems. It is suggested that the alpha-subunits of the oligomycin-sensitive coupling factor catalyze synthesis and the beta-subunits catalyze hydrolysis. Evidence is assembled from the literature in support of this concept.     

Are there knobs on energy transducing membranes in situ?

It is argued here that the projections which are frequently seen on the matrix side of the mitochondrial inner membranes and which are characterized as globules or spherical projections or as knob-on-stalks are an artifact of the preparation and/or of the staining of the submitochondrial particles or mitochondria. In sectioned or freeze-fractured preparations of intact cells or mitochondria, the externalized spheres are rarely seen on the membranes. They are, however, almost always seen on fragmented preparations, especially if they have been negatively stained with phosphotungstate.     

Polymethionyl,-valyl and-glycyl derivatives of equine heart cytochromec heme octapeptide

Polymethionyl ((Met)_5·3-H8PT), polyvalyl ((Val)_4·4-H8PT) and polyglycyl ((Gly)_3·2-H8PT) derivatives of the heme octapeptide of equine heart cytochrome c were prepared with the aid of the N-carboxyl anhydrides of their respective amino acids. Only for the (Met)_5·3-H8PT did the γ-peak in the absorption spectrum of the reduced form shift from 412.5 nm, the value for the unsubstituted octapeptide, to 414 nm, the value close to the γ-peak of intact ferrocytochrome c. The γ-peak of the oxidized form of the octapeptide did not shift significantly from 397 nm. Amino acids attached to the N-terminal cysteine of the octapeptide, with methionine excepted, have little or no effect on the spectrum, and apparently cannot serve as either an intramolecular or intermolecular ligand for the iron. This result is in marked contrast to those previously obtained with the substituted cytochrome c heme undecapeptide (ref. 8) where all three derivatives had altered spectra. For the octapeptide, the ratio, absorbance of the γ-peak of the oxidized form to absorbance of the γ-peak of the reduced form, did not change appreciably for any of the derivatives, although when the reaction products from excess methionine anhydride were present (before centrifugation and dialysis) the ratio was lower and approached the ratio for cytochrome c.