Demographic Analysis of Shortfin Mako Shark (Isurus oxyrinchus) in the South Pacific Ocean.

The shortfin mako shark (Isurus oxyrinchus) demonstrates low productivity and is thus relatively sensitive to fishing. Natural mortality (M) and fishing mortality (F) data are critical to determine their population dynamics. However, catch and fishing effort data are unavailable for this species in the South Pacific Ocean, making stock assessments difficult. Demographic quantitative methods aid in analyzing species with limited data availability. We used a two-sex stage-structured matrix population model to examine the demographic stock status of mako sharks. However, data-limited models to determine fishery management strategies have limitations. We performed Monte Carlo simulations to evaluate the effects of uncertainty on the estimated mako shark population growth rate. Under unfished conditions, the simulations demonstrated that the mako sharks showed a higher finite population growth rate in the 2-year reproductive cycle compared to the 3-year reproductive cycle. Protecting immature mako sharks led to a higher population growth rate than protecting mature mako sharks. According to the sex-specific data, protecting immature male and female sharks led to a higher population growth rate than protecting mature male and female sharks. In conclusion, sex-specific management measures can facilitate the sustainable mako shark conservation and management.

Effects of tethering alkyl chains for amphiphilic ruthenium complex dyes on their adsorption to titanium oxide and photovoltaic properties.

Ruthenium (II) complex dye, Ru(4,4'-dicarboxyl-2,2'-bipyridine)(4-nonyl-2,2'-bipyridine) (NCS)(2), (denoted as RuC9) tethering single alkyl chain was synthesized and well characterized. Its adsorption behavior onto the mesoporous TiO(2) and photovoltaic properties were compared with Z907 which has similar chemical structure but tethers two alkyl chains. RuC9 dyes tend to aggregate into vesicles in the acetonitrile/t-butanol co-solvent as a result of the amphiphilic structure, whereas Z907 dyes aggregate into lamellae. The dye-sensitized solar cell (DSSC) with RuC9 dye showed higher short-circuit photocurrent than that with Z907, attributing to its higher molar optical extinction coefficient and more adsorption amount onto the mesoporous TiO(2). However, the DSSC with Z907 dye has higher open-circuit photovoltage and power conversion efficiency, presumably due to the fact that Z907 with more alkyl chains formed a molecular layer with higher hydrophobicity. It reduced the charge recombination in the interface between the dye-sensitized mesoporous TiO(2) and electrolyte as verified by the electrochemical impedance spectroscopy and intensity modulated photocurrent and photovoltage spectroscopies.

Hindbrain administration of NMDA receptor antagonist AP-5 increases food intake in the rat.

Hindbrain administration of MK-801, a noncompetitive N-methyl-D-aspartate (NMDA) channel blocker, increases meal size, suggesting NMDA receptors in this location participate in control of food intake. However, dizocilpine (MK-801) reportedly antagonizes some non-NMDA ion channels. Therefore, to further assess hindbrain NMDA receptor participation in food intake control, we measured deprivation-induced intakes of 15% sucrose solution or rat chow after intraperitoneal injection of either saline vehicle or D(-)-2-amino-5-phosphonopentanoic acid (AP5), a competitive NMDA receptor antagonist, to the fourth ventricular, or nucleus of the solitary tract (NTS). Intraperitoneal injection of AP5 (0.05, 0.1, 1.0, 3.0, and 5.0 mg/kg) did not alter 30-min sucrose intake at any dose (10.7 +/- 0.4 ml, saline control) (11.0 +/- 0.8, 11.2 +/- 1.0, 11.2 +/- 1.0, 13.1 +/- 2.2, and 11.0 +/- 1.9 ml, AP5 doses, respectively). Fourth ventricular administration of both 0.2 mug (16.7 +/- 0.6 ml) and 0.4 mug (14.9 +/- 0.5 ml) but not 0.1 and 0.6 mug of AP5 significantly increased 60-min sucrose intake compared with saline (11.2 +/- 0.4 ml). Twenty-four hour chow intake also was increased compared with saline (AP5: 31.5 +/- 0.1 g vs. saline: 27.1 +/- 0.6 g). Furthermore, rats did not increase intake of 0.2% saccharin after fourth ventricular AP5 administration (AP5: 9.8 +/- 0.7 ml, vs. saline: 10.5 +/- 0.5 ml). Finally, NTS AP5 (20 ng/30 nl) significantly increased 30- (AP5: 17.2 +/- 0.7 ml vs. saline: 14.6 +/- 1.7 ml), and 60-min (AP5: 19.4 +/- 0.6 ml vs. saline: 15.5 +/- 1.4 ml) sucrose intake, as well as 24-h chow intake (AP5: 31.6 +/- 0.3 g vs. saline: 26.1 +/- 1.2 g). These results support the hypothesis that hindbrain NMDA receptors participate in control of food intake and suggest that this participation also may contribute to control of body weight over a 24-h period.

Intracerebroventricular administration of MK-801 increases food intake through mechanisms independent of gastric emptying.

Systemic or hindbrain administration of MK-801, a noncompetitive N-methyl-D-aspartate receptor antagonist, increases meal size. To examine whether MK-801 enhances intake by increasing gastric emptying, we administered MK-801 (2.0 microg/3.0 microl) into the fourth ventricle [intracerebroventricular (ICV)] and measured feeding and gastric emptying of 5-ml NaCl or 15% sucrose loads. In a parallel experiment, we examined food intake and gastric emptying following intraperitoneal (IP) injection of MK-801 (100 microg/kg). MK-801, either IP or ICV, increased 30-min sucrose intake compared with control (12.3 +/- 0.7 vs. 9.8 +/- 0.5 and 16.6 +/- 2.0 vs. 10.7 +/- 0.7 ml, for IP and ICV administration, respectively). Also, IP MK-801 increased 5-min gastric emptying of NaCl (4.13 +/- 0.1 ml emptied) and sucrose (3.11 +/- 0.1 ml emptied) compared with control (3.75 +/- 0.2 and 2.28 +/- 0.1 ml emptied for NaCl and sucrose loads, respectively). In contrast, ICV MK-801 did not alter NaCl emptying (3.82 +/- 0.1 ml emptied) compared with control (3.82 +/- 0.3 ml emptied) and actually reduced gastric emptying of sucrose (2.1 +/- 0.2 and 2.94 +/- 0.1 ml emptied, for MK and vehicle, respectively). These data confirm previous results that systemic as well as hindbrain injection of MK-801 increases food intake. However, because ICV MK-801 failed to increase gastric emptying, these results indicate that MK-801 increases food intake through mechanisms independent of altered gastric emptying.