Dental variability of the Liberian chimpanzee,Pan troglodytes verus

Dental variability was studied in a collection of Liberian chimpanzee (Pan troglodytes verus) crania from one geographic area of Central Liberia. Morphological and metric data were compared to another population of the same subspecies studied by Schuman and Brace (1955) as well as to other pongid taxa. It appears that of all living pongids, chimpanzees are the most derived in their lower molar patterns, particularly, P. t. verus. It is clear, however that the mandibular molar patterns of contemporary chimpanzees are more similar to other pongids that to humans which is contra to the suggestions of Schuman and Brace. Hypocone reduction from M1 to M3 is the common pattern in all hominoids. Complete absence of the M3 hypocone is rare in pongids but it is present in the Frankfurt collection. Of living pongids, the gorilla expresses the least amount of hypocone reduction from M1 to M3. A cusp of Carabelli is recorded bilaterally in one P.t. verus. There is less odontometric variation in P.t. verus than in other pongids as indicated by the CV’s which may suggest the greater dental variability present when different geographic groups are included in the sample.     

Purification and Characterization of Cytochrome P450 Reductase from Liver Microsomes of Feral Leaping Mullet (Liza saliens)

NADPH-cytochrome P450 reductase was purified to electrophoretic homogeneity from detergent-solubilized liver microsomes from the leaping mullet (Liza saliens). The purified reductase was characterized with respect to spectral, electrophoretic, and biocatalytic properties. In addition, effects of pH, ionic strength, and the substrate concentration on the NADPH-dependent cytochrome c reductase activity of the purified fish liver cytochrome P450 reductase were studied. Cytochrome P450 reductase was purified 438-fold with a yield of 17.5% with respect to the initial amount present in the fish liver microsomes. The specific activity of the enzyme was found to be 52.6 μmol cytochrome c reduced per minute per mg protein. The monomer molecular weight of the purified enzyme was calculated to be 77,000 ± 1000 when electrophoresed on polyacrylamide gels under the denaturing conditions in the presence of SDS. The absorption spectrum of fish reductase showed two peaks at 378 and 455 nm. NADPH-dependent cytochrome c reductase activity of the purified Liza saliens liver cytochrome P450 reductase was found to be maximal when pH was between 7.4 and 7.8. The apparent K_m of the purified enzyme was found to be 7.69 μM for cytochrome c when the enzyme activity was measured in 0.3 M potassium phosphate buffer, pH 7.7, at room temperature, and the enzyme was fully saturated by its substrate, cytochrome c, when the substrate concentration was at or above the 70 μM. Furthermore, the purified enzyme was biocatalytically active in reconstituting the 7-ethoxyresorufin O-deethylase activity in the reconstituted system containing purified mullet liver cytochrome P4501A1 and lipid. These results suggested that the purified fish liver cytochrome P450 reductase is similar to its mammalian counterparts with respect to spectral, electrophoretic, and biocatalytic properties. © 1997 John Wiley & Sons, Inc. J Biochem Toxicol 12: 103–113, 1998     

Differential Trk expression in explant and dissociated trigeminal ganglion cell cultures

During embryonic development, expression of neurotrophin receptor tyrosine kinases (Trks) by sensory ganglia is continuously and dynamically regulated. Neurotrophin signaling promotes selective survival and axonal differentiation of sensory neurons. In embryonic day (E) 15 rat trigeminal ganglion (TG), NGF receptor TrkA is expressed by small diameter neurons, NT-3 receptor TrkC and BDNF receptor TrkB are expressed by large diameter neurons. Organotypic explant and dissociated cell cultures of the TG (and dorsal root ganglia) are commonly used to assay neurotrophin effects on developing sensory neurons. In this study, we compared Trk expression in E15 rat TG explant and dissociated cell cultures with or without neurotrophin treatment. Only a subset of TG cells express each of the three Trk receptors in wholemount explant cultures as in vivo conditions. In contrast, all TG neurons co-express all three Trk receptors upon dissociation, regardless of neurotrophin treatment. Neurons cultured in low concentrations of one neurotrophin first, and switched to higher concentrations of another after 1 day, survive and display morphological characteristics of neurons cultured in a mixture of both neurotrophins for 3 days. Our results indicate that wholemount explant cultures of sensory ganglia represent in vivo conditions in terms of Trk expression patterns; whereas dissociation dramatically alters Trk expression by primary sensory neurons.     

Leptin ameliorates burn-induced multiple organ damage and modulates postburn immune response in rats

The present study was designed to determine whether exogenous leptin reduces remote organ injury in the rats with thermal burn trauma. Leptin (10 microg/kg) or saline was administered intraperitoneally after burn injury, and the rats were decapitated at either 6 or 24 h. Plasma samples of 24-h burn group were assayed for the determination of monocyte and neutrophil apoptosis. Thermal injury increased tissue-associated myeloperoxidase (MPO) activity and microscopic damage scores in the lung, liver, stomach, colon and kidney of both 6- and 24-h burn groups. In the 6-h burn group, leptin reduced microscopic damage score in the liver and kidney only, while damage scores in the 24-h burn group were reduced in all the tissues except the lung. Also, in both burn groups, leptin reduced elevated MPO activity in all tissues except the lung. The percentage of mononuclear cells was significantly reduced at the 24 h of burn injury, while the granulocyte percentage was increased. Leptin treatment, however, had no significant effect on burn-induced reversal of white blood cell ratios. On the other hand, burn-induced increase in the death of mononuclear cells and granulocytes was significantly reduced in leptin-treated rats. The results of the present study suggest that leptin may provide a therapeutic benefit in diminishing burn-induced inflammation and associated multiple organ failure.     

Effects of HA-1077 and Y-27632, two rho-kinase inhibitors, in the human umbilical artery

A role for the small G protein rho and rho-kinase has been shown in smooth muscle contraction regarding Ca⁺⁺ sensitivity. However, there are no data in the literature assessing how this system operates in human umbilical arteries (HUA). Therefore, we evaluated the effects of HA-1077 and Y-27632, two rho-kinase inhibitors, on agonist-(5-hydroxytryptamine [5-HT]) and depolarization-induced (KCl) contractions of HUA. HA-1077 and Y-27632 inhibited 5-HT-induced contractile responses at 10⁻⁴ M concentration but not at 10⁻⁵ M. HA-1077 at 10⁻⁴ M also significantly attenuated contractions induced by 20 mM KCl. In addition, HUA precontracted with 5-HT relaxed concentration dependently in response to HA-1077 and Y-27632. When precontracted with KCl, HUA also relaxed dose-dependently in response to HA-1077, but the maximal relaxation was significantly smaller than the response obtained when precontracted with 5-HT. To determine possible involvement of rho-kinase on agonist-induced intracellular calcium-mediated contractions, tissues were precontracted with 5-HT in Ca⁺⁺-free Krebs solution before cumulative addition of HA-1077 or Y-27632 (10⁻⁷ to 10⁻⁴ M). Both rho-kinase inhibitors relaxed HUA completely. Maximum relaxations of HUA to HA-1077 and Y-27632 were significantly larger than the responses seen in normal Krebs solution and were obtained with lower concentrations of the drugs considered to be more specific for rho-kinase inhibition. However, preincubation of HUA with HA-1077 or Y-27632 (10⁻⁵ M for both) did not affect the 5-HT-induced contractions in this medium. Finally, immunoblot experiments revealed the expression of rho-kinase isoform rockII protein in HUA. These results indicate that rhoA/rho-kinase pathway can contribute to agonist-induced contractions of HUA. However, this effect appears to be limited to intracellular calcium-induced contractions and may be more important in sustaining contractions rather than the initial phase of force development.     

Considering alternative life history modes and genetic divergence in conservation: a case study of the Oklahoma salamander

Alternative life history strategies can provide important variation for the long-term persistence of a lineage. However, conservation of such lineages can be complicated because each life history mode may have different habitat requirements and may be vulnerable to different environmental perturbations. The Oklahoma salamander (Eurycea tynerensis) is endemic to the Ozark Plateau of North America, and has two discrete life history modes, biphasic (metamorphic) and aquatic (paedomorphic). Until recently, these modes were considered separate species and conservation attention focused only on paedomorphic populations. We perform phylogenetic analyses of the mitochondrial gene cytochrome b (Cytb) and nuclear gene proopiomelanocortin (POMC) to assess patterns of historical isolation in E. tynerensis, and test whether life history mode is randomly distributed with respect to the phylogeny and geography. We find three divergent Cytb lineages and significant shifts in POMC allele frequencies between the eastern, western, and southwestern portions of the distribution. Life history mode varies extensively, but paedomorphosis is largely restricted to the widespread western clade. Therefore, the two most divergent and narrowly distributed clades (southwestern and eastern) were previously overlooked due to their metamorphic life history. Paedomorphosis has allowed E. tynerensis to drastically increase its niche breadth and distribution size. Nevertheless, metamorphosis is also an important attribute, and metamorphic populations are the ultimate source for paedomorphic evolution. Preservation of divergent genetic lineages, and regions that include adjacent habitat for both life history modes, may be the most effective way to maintain historical and adaptive variation and provide gateways for ongoing life history evolution.