Habitat selection and territorial defense behaviors in juvenile cortez angelfish,Pomacanthus zonipectus (gill)

Scuba diving observations in the Gulf of California (Mexico) on juvenile Cortez angelfishes, Pomacanthus zonipectus (Gill), indicate that these fish select and defend territories centered about a rock crevice. By day, they make brief feeding excursions, venturing even over open sandy areas near the rocks. They are substrate feeders, and will remove ectoparasites from other fishes, even attempting to clean human divers. At night they remain in their rock crevices. Laboratory experiments, conducted to quantify habitat-selection and territorial-defense behaviors in juvenile P. zonipectus, revealed that they spend 75% of their time during the day near rocks and 25% over sand in a divided experimental tank. The frequency of attacks on a mirror image increased as the mirror was moved closer to the rock crevice which was the territorial focus.     

5-Lipoxygenase Metabolites of Arachidonic Acid Regulate Volume Decrease by Mudpuppy Red Blood Cells

We examined whether metabolites of arachidonic acid (AA) regulate K⁺ efflux during regulatory volume decrease (RVD) by mudpuppy red blood cells (RBCs). Volume regulation was inhibited by the phospholipase A₂ antagonists mepacrine (10 μm) and ONO-RS-082 (10 μm); the inhibitory effect of ONO-RS-082 was reversed by gramicidin (5 μm). Eicosatetraynoic acid (ETYA, 100 μm), a general antagonist of AA metabolism, also blocked RVD. In addition, volume regulation was inhibited by the lipoxygenase pathway antagonist nordihydroguaiaretic acid (NDGA, 10 μm), the 5 lipoxygenase antagonists AA-861 (5 μm) and curcumin (20 μm), and by the 5-lipoxygenase activating protein inhibitor L-655,298 (5 μm). Inhibition by all four of these agents was reversed with gramicidin. In contrast, the 12- and 15-lipoxygenase pathway inhibitor ethyl-3,4-dihydroxy-benzylidene-cyanoacetate (EDBCA, 1 μm) and the cytochrome P-450 monooxygenase pathway blocker ketoconazole (20 μm) had no effect. On the other hand, the cyclooxygenase pathway inhibitor aspirin (100 μm) slightly enhanced RVD. Consistent with these findings, a K⁺-selective whole cell conductance responsible for K⁺ efflux during cell swelling was inhibited by ONO-RS-082 (10 μm), NDGA (10 μm), AA-861 (5 μm), curcumin (20 μm), and l-655,298 (5 μm). In contrast, EDBCA (1 μm), ketoconazole (20 μm), and indomethacin (10 μm) did not block this whole cell conductance. These results indicate that a channel mediating K⁺ loss during RVD is regulated by a 5-lipoxygenase metabolite of arachidonic acid. Received: 12 December 1996/Revised: 28 February 1997     

Protein Kinase C and Regulatory Volume Decrease in Mudpuppy Red Blood Cells

This study examined whether protein kinase C (PKC) stimulates K⁺ efflux during regulatory volume decrease (RVD) in Necturus maculosus (mudpuppy) red blood cells (RBCs). The limit of osmotic fragility increased with the general protein kinase inhibitor 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H-7, 10 μm), but not with the cyclic nucleotide-dependent kinase antagonists N-(2′-guanidinoethyl)-5-isoquinolinesulfonamide (HA-1004, 10 μm) and N-2-(methylamino)ethyl-5-isoquinoline-sulfonamide (H-8, 5 μm). Consistent with these results, osmotic fragility also increased with the PKC antagonists bisindolylmaleimide I (GF-109203X or bis I, 100 nm), bisindolylmaleimide II (bis II, 100 nm), and chelerythrine (10 μm). The effect of these three antagonists and H-7 was reversed with gramicidin (5 μm in a choline Ringer), indicating PKC was linked to K⁺ efflux (gramicidin is a cationophore that was used to ensure a high K⁺ permeability). We also measured cell volume recovery from hypotonic shock (0.5× Ringer) with a Coulter counter and estimated cell volume from the hematocrit. The percent RVD compared to control decreased with H-7 (10 μm), sphingosine (100 nm), chelerythrine (10 μm), bis I (100 nm), and bis II (100 nm), but not with HA-1004 (10 μm) nor H-8 (5 μm). Inhibition of RVD by H-7, chelerythrine, bis I, and bis II was reversed with gramicidin (5 μm). Furthermore, using the patch clamp technique, we found H-7 (10 μm) reduced a whole cell conductance that was activated during cell swelling. In addition, a conductance responsible for K⁺ efflux during cell swelling was inhibited by bis I (100 nm) and bis II (100 nm). These results indicate that a conductive pathway mediating K⁺ loss during RVD is regulated, at least in part, by protein kinase C. Received: 20 January 1998/Revised: 2 September 1998     

Tolerance of Pomacanthus imperator to hypoosmotic salinities: changes in body composition and hepatic enzyme activities

Emperor angel fish Pomacanthus imperator were acclimated to various salinities (33, 22, 15, 10 and 7%) for 1 month and changes in serum chemistry, body composition and liver enzyme activities were monitored. No mortality was observed in fish adapted throughout the salinity range of 7–33% and the limit of survival was around 5%. Serum Na^+; and Cl ^– exhibited a stepwise decrease as the salinity was reduced from 33–7% but no concomitant tissue hydration could be observed. Branchial Na-K-ATPase activity was generally higher in hypoosmotic (7–15%) than in hyperosmotic salinities (22–33%o). Serum concentrations of glucose, lipid, α-amino acids and protein as well as the haematocrit value were all elevated in the salinity range of 15–22%. Serum cortisol was markedly lower but serum thyroxine was significantly elevated at 15–22%. Fish adapted to 15–22% had higher hepatosomatic indices, liver glycogen and muscle lipid contents and hepatic glucose-6-phosphate dehydrogenase activity. These data indicate that Pomacanthus imperator is a' physiologically euryhaline' species and metabolism in isoosmotic salinities has been fundamentally re-organized to favour carbohydrate and lipid retention.     

Consequences of marine barriers for genetic diversity of the coral‐specialist yellowbar angelfish from the Northwestern Indian Ocean

Ocean circulation, geological history, geographic distance, and seascape heterogeneity play an important role in phylogeography of coral‐dependent fishes. Here, we investigate potential genetic population structure within the yellowbar angelfish (Pomacanthus maculosus) across the Northwestern Indian Ocean (NIO). We then discuss our results with respect to the above abiotic features in order to understand the contemporary distribution of genetic diversity of the species. To do so, restriction site‐associated DNA sequencing (RAD‐seq) was utilized to carry out population genetic analyses on P. maculosus sampled throughout the species’ distributional range. First, genetic data were correlated to geographic and environmental distances, and tested for isolation‐by‐distance and isolation‐by‐environment, respectively, by applying the Mantel test. Secondly, we used distance‐based and model‐based methods for clustering genetic data. Our results suggest the presence of two putative barriers to dispersal; one off the southern coast of the Arabian Peninsula and the other off northern Somalia, which together create three genetic subdivisions of P. maculosus within the NIO. Around the Arabian Peninsula, one genetic cluster was associated with the Red Sea and the adjacent Gulf of Aden in the west, and another cluster was associated with the Arabian Gulf and the Sea of Oman in the east. Individuals sampled in Kenya represented a third genetic cluster. The geographic locations of genetic discontinuities observed between genetic subdivisions coincide with the presence of substantial upwelling systems, as well as habitat discontinuity. Our findings shed light on the origin and maintenance of genetic patterns in a common coral reef fish inhabiting the NIO, and reinforce the hypothesis that the evolution of marine fish species in this region has likely been shaped by multiple vicariance events.     

Four new species of <Emphasis Type="Italic">Crinipellis </Emphasis>and <Emphasis Type="Italic">Marasmius </Emphasis>in eastern Honshu,Japan

 Four new species of Crinipellis and Marasmius (Agaricales, Basidiomycetes) in eastern Honshu, Japan, are described and illustrated: (1) Crinipellis conchata sp. nov. (section Excentricinae), forming a conchate pileus and a strongly excentric, short stipe, was found on a dead twig of Trachelospermum asiaticum in Mt. Takao, Tokyo; (2) Marasmius funalis sp. nov. (section Androsacei), forming a densely white-hispid, dark brown stipe bearing numerous setiform caulocystidia, was found on a dead twig of Cryptomeria japonica or on leaf litter in Tokyo and Kanagawa; (3) Marasmius maculosus sp. nov. (section Sicci), having a relatively large, reddish-brown pileus distinctly mottled with pale colored spots and Siccus-type cheilocystidia and pileipellis cells with relatively long setulae, was found on leaf litter in the lowland forest of Kanagawa and Chiba; and (4) Marasmius sasicola sp. nov. (section Marasmius), having a small, plicate-sulcate pileus, a filiform, wiry, blackish stipe, collariate lamellae, and Siccus-type cheilocystidia and pileipellis elements, was found on fallen dead leaves of grass bamboo in Kanagawa. Received: January 30, 2002 / Accepted: May 24, 2002