Vulnerability of birds to contaminated water sources in the Karoo region of South Africa

The Karoo is a unique region in South Africa in terms of its ecological processes and endemic species. Large areas are needed to maintain viable populations of nomadic birds that follow erratic rainfall events and subsequent food and nesting resources, as well as ephemeral standing water. Whereas many species are adapted to arid conditions, our trait-based analysis found that an unusually large percentage (almost 45%) of 315 bird species in the semi-arid Karoo region rely on water to some degree. Indeed, some birds may have benefited from human activities to date, such as through the provision of water for livestock. However, this reliance on water makes birds vulnerable to changes in water quality stemming from various industrial developments. Given the large areas of the Karoo under consideration for concessions, the most noteworthy of these is hydraulic fracturing for shale gas, which results in a large quantity of waste water (‘produced water’) that contains a wide variety of chemicals, including petroleum byproducts. Given the negative impacts of secondary waste water on wildlife in other parts of the world where shale-gas exploration is being undertaken, careful attention must be given to preventing access to such produced water by an estimated 60 to 141 species of birds that make use of the water in the Karoo.     

The proteinase inhibitor camostat mesilate suppresses pancreatic pain in rodents

Camostat mesilate, an orally available proteinase inhibitor, is clinically used for treatment of pancreatitis. Given recent evidence that pancreatic proteinases including trypsin and/or proteinase-activated receptor-2 (PAR2) might be involved in pancreatic pain, we examined if camostat mesilate could suppress spinal Fos expression, a marker for neuronal activation, following specific application of trypsin to the pancreas, and pancreatitis-related referred allodynia. Trypsin, administered into the pancreatic duct, caused delayed expression of Fos proteins in the superficial layer of the bilateral T8 and T9 spinal dorsal horns in rats. The trypsin-induced spinal Fos expression was completely abolished by oral pre-administration of camostat mesilate at 300 mg/kg. After hourly repeated (6 times in total) administration of caerulein, mice showed typical symptoms of pancreatitis, accompanied by mechanical allodynia in the upper abdomen (i.e., referred hyperalgesia/allodynia), as assessed by use of von Frey filaments. Camostat mesilate at 100-300 mg/kg, given orally twice before the 1st and 4th doses of caerulein, abolished the pancreatitis-related abdominal allodynia, while it partially prevented the inflammatory signs. The same doses of camostat mesilate, when administered once after the final dose of caerulein, also revealed significant anti-allodynic effect. These data suggest that camostat mesilate prevents and/or depresses pancreatitis-induced pain and/or referred hyperalgesia/allodynia, in which proteinases including trypsin would play a critical role.     

An aldose reductase inhibitor prevents the glucose-induced increase in PDGF-beta receptor in cultured rat aortic smooth muscle cells.

To examine the role of platelet-derived growth factor (PDGF) and the polyol pathway in the growth activity of smooth muscle cells (SMCs), [(3)H]-thymidine incorporation, [(125)I]-PDGF-BB binding and expression of PDGF-beta receptor protein were measured in rat aortic SMCs cultured with 5.5 or 20 mM glucose with or without anti-PDGF antibody or an aldose reductase inhibitor, epalrestat. SMCs cultured with 20 mM glucose demonstrated an accelerated thymidine incorporation compared with SMCs cultured with 5.5 mM glucose, which was prevented by anti-PDGF antibody. This acceleration of growth activity by 20 mM glucose was accompanied by an increase in PDGF-BB binding, which was due to the increased number of PDGF-beta receptors and the overexpression of PDGF-beta receptor protein. Epalrestat prevented all these abnormalities. These observations suggest that polyol pathway hyperactivity plays an important role in the proliferation of SMCs which may be mediated through the accelerated expression of PDGF-beta receptor protein.     

Purification and characterization of phosphodiesterase from the venom of Trimeresurus mucrosquamatus

Phosphodiesterase was isolated from the venom of Trimeresurus mucrosquamatus from Taiwan using gel filtration on a Sephadex G-100 column, followed by anion or cation exchange chromatography. Phosphodiesterase was homogeneous as established by a single band on acrylamide gel electrophoresis and immunodiffusion. Phosphodiesterase activity was inhibited by ethylenediamine tetraacetic acid (EDTA), o-phenanthroline, thioglycolic acid or p-chloromercuribenzoate (PCMB) but not by soybean trypsin inhibitor (SBTI) or benzamidine. The molecular weight of this enzyme was determined to be approximately 140,000 and the isoelectric point was found to be pH 7.4 by isoelectric focusing with carrier ampholyte. The Michaelis constant (Km) of this enzyme for p-nitrophenyl thymidine-5'-phosphate and inhibition constant (Ki) for PCMB were found to be 5.6 X 10(-3) and 7.6 X 10(-4) M, respectively.     

Effect of sodium ion on atrial natriuretic factor release from rat hypothalamic fragments

The effects of Na ion and choline chloride on the release of atrial natriuretic factor (ANF) and growth hormone-releasing factor (GHRF) from rat hypothalamic fragments including the organum vasculosum of the lamina terminalis (OVLT) were examined in vitro. Although the release of ANF was stimulated by Na ion, choline chloride, and glucose in concentration-dependent manners, the release was more sensitive to a change in concentration of Na ion than to those of choline chloride and glucose. On the other hand, the change in Na ion concentration did not affect the release of GHRF. It can be therefore proposed that Na ion is the first candidate controlling ANF release from the brain tissue and that ANF in the hypothalamus and/or OVLT may play some role in the regulation of the Na ion and water balance in the central nervous system.     

Differences in the pharmacological actions of intrathecally administered neurotensin and morphine

Neurotensin or morphine can each cause hypothermia and an antinocisponsive effect when administered into the liquor spaces of the rat brain. These actions of neurotensin are not blocked by naloxone whereas those of morphine are. The present experiments were carried out to examine the action of each substance following its injection into the subarachnoid space of the spinal cord. Given intrathecally, neurotensin evoked a dose-related fall in the rectal temperature of the rat without exerting an antinocisponsive action. Morphine on the other hand evoked hyperthermia and a dose-related antinocisponsive action. Since neurotensin exerted an effect on rectal temperature opposite to that of morphine and failed to exert an antinocisponsive effect, the data provide further evidence to suggest that neurotensin and morphine exert their effect via different mechanisms. Furthermore, the results also suggest that neurotensin exerts its antinocisponsive action via a supraspinal site.     

Evolutionary analysis of putative olfactory receptor genes of medaka fish, Oryzias latipes

To obtain an understanding of the origin, diversification and genomic organization of vertebrate olfactory receptor genes, we have newly cloned and characterized putative olfactory receptor genes, mfOR1, mfOR2, mfOR3 and mfOR4 from the genomic DNA of medaka fish (Oryzias latipes). The four sequences contained features commonly seen in known olfactory receptor genes and were phylogenetically most closely related to those of catfish and zebrafish.Among them, mfOR1 and mfOR2 showed the highest amino acid (aa) similarity (93%) and defined a novel olfactory receptor gene family that is most divergent among all other vertebrate olfactory receptor genes. Southern hybridization analyses suggested that mfOR1 and mfOR2 are tightly linked to each other (within 24kb), although suitable marker genes were not available to locate their linkage group. Unlike observation in catfish olfactory receptor sequences, nucleotide (nt) substitutions between the two sequences did not show any evidence of positive natural selection. mfOR3 and mfOR4, however, showed a much lower aa similarity (26%) and were both mapped to a region in the medaka linkage group XX.After including these medaka fish sequences, olfactory receptors of terrestrial and aquatic animals formed significantly different clusters in the phylogenetic tree. Although the member genes of each olfactory receptor gene subfamily are less in fish than that in mammals, fish seem to have maintained more diverse olfactory receptor gene families. Our finding of a novel olfactory receptor gene family in medaka fish may provide a step towards understanding the emergence of the olfactory receptor gene in vertebrates.