Central and peripheral administration of amylin induces energy expenditure in anesthetized rats

Amylin is a peptide hormone that is co-released with insulin from pancreatic β-cells following a meal. Intracerebroventricular (icv) administration of amylin (1–100 pmol), or an amylin agonist, salmon calcitonin, elicited dose-dependent thermogenic, tachycardic, and hyperthermic responses in urethane-anesthetized rats. Intravenous (iv) administration of higher doses of amylin (100 pmol–20 nmol) also induced similar responses, although the amplitudes of these responses were significantly smaller than those elicited by icv administration, suggesting the primary action of amylin to be in the brain. However, the iv administration of amylin induced the responses slightly faster than the icv injection, the former responses occurring <4 min and the latter, at 8–10 min, after the administration. The iv but not the icv injection of amylin increased the respiratory exchange ratio transiently (<20 min), though the thermogenic response lasted for a longer period after both injections, indicating a shift from mixed fuel to predominantly carbohydrate utilization in the initial phase of thermogenesis induced by the iv injection of amylin. The differences in substrate utilization and latency of the responses suggest that the actions of amylin include partly different targets when administered centrally and peripherally. Moreover, pretreatment with a β-adrenergic blocker, propranolol (5 mg kg⁻¹, iv), blocked all responses elicited by either icv or iv administration of amylin, whereas ablation of the area postrema in the hindbrain did not influence the effects of icv-administered amylin. These results suggest the involvement of amylin in postprandial energy expenditure, mediated by peripheral β-adrenoceptors.     

Ecological Aspects of the Downstream Migration of Introduced European Eels in the Uono River, Japan

We examined the species composition, timing of downstream migration, and biological characteristics of eels using catches at three commercial weirs from 1996 to 1998 in the Uono River, Niigata Prefecture, Japan, which is located farther north in the Japan Sea than where most Japanese eels, Anguilla japonica, recruit. Analyses of a sub-sample of the 292 eels caught in the weirs found that 93.6% were introduced European eels, Anguilla anguilla, that were sexually maturing silver phase eels. Their average age based on otolith annuli was 10.2 years, indicating a relatively high average growth rate of 6.3 cm year^–1. Catch records in 1996 and 1997 indicated that downstream migration occurred sporadically from the middle of August to the end of November and that catches generally coincided with abrupt increases in water discharge and drops in water temperature. The highest catches in both years occurred between the last quarter and new moon. These findings were similar to studies on this species in Europe and indicate that A. anguilla can grow rapidly, begin maturation, and start downstream migration far from its native range. This discovery of introduced eels initiating their spawning migration at the same time as A. japonica raises concerns about the potential impact of interbreeding between species and the possible effects on the fishery resources of A. japonica.     

Characterization of microsatellite loci from the Japanese eel Anguilla japonica

The Japenese eel, Anguilla japonica, is generally assumed to be composed of a single population with wide distribution range, and some genetic studies using allozyme or mitochondrial DNA methods supported this population model. However, one genetic study suggested the existence of multiple populations in this species, and thus, more detailed studies on the population structure is needed. Here we characterized a total of 11 microsatellite markers of the Japanese eel. These will serve as powerful tools for detailed population study for the Japanese eel, though two of them showed the significant departure from the Hardy–Weinberg expectations.     

Exclusive association of paraoxonase 1 with high-density lipoprotein particles in apolipoprotein A-I deficiency.

Paraoxonase1 (PON1) is a high-density lipoprotein (HDL)-associated protein which removes peroxidized lipids from lipoproteins. It has been proposed that apolipoprotein A-I (apoA-I) is an important determinant for its stabilization on HDL. However, little is known about its existence and activity in an apoA-I-deficient state in humans. To characterize the nature of PON1 in apoA-I deficiency, we investigated PON1 in an apoA-I-deficient patient. When serum was analyzed on fast protein liquid chromatography, PON1 protein was distributed almost exclusively on HDL despite the absence of apoA-I; on the other hand, 38.5% of PON1 protein was found in the lipoprotein-free fraction when the lipoproteins were fractionated through ultracentrifugation. The stability of PON1 activity in the patient serum was almost the same as in the normal control sera throughout incubation at 14 degrees C for 7 days. However, when the sera were incubated at 37 degrees C for 24 h, its activity declined more than those in the normal controls (19% versus 4% reduction of the initial values). Our results demonstrated that PON1 protein possesses a preferential association with HDL even in the absence of apoA-I, although apoA-I is a crucial factor for the maximal activity and stabilization of PON1.     

The role of the Mre11-Rad50-Xrs2 complex in telomerase- mediated lengthening of Saccharomyces cerevisiae telomeres.

BACKGROUND: The Saccharomyces Mre11p, Rad50p, and Xrs2p proteins form a complex, called the MRX complex, that is required to maintain telomere length. Cells lacking any one of the three MRX proteins and Mec1p, an ATM-like protein kinase, undergo telomere shortening and ultimately die, phenotypes characteristic of cells lacking telomerase. The other ATM-like yeast kinase, Tel1p, appears to act in the same pathway as MRX: mec1 tel1 cells have telomere phenotypes similar to those of telomerase-deficient cells, whereas the phenotypes of tel1 cells are not exacerbated by the loss of a MRX protein. RESULTS: The nuclease activity of Mre11p was found to be dispensable for the telomerase-promoting activity of the MRX complex. The association of the single-stranded TG1-3 DNA binding protein Cdc13p with yeast telomeres occurred efficiently in the absence of Tel1p, Mre11p, Rad50p, or Xrs2p. Targeting of catalytically active telomerase to the telomere suppressed the senescence phenotype of mec1 mrx or mec1 tel1 cells. Moreover, when telomerase was targeted to telomeres, telomere lengthening was robust in mec1 mrx and mec1 tel1 cells. CONCLUSIONS: These data rule out models in which the MRX complex is necessary for Cdc13p binding to telomeres or in which the MRX complex is necessary for the catalytic activity of telomerase. Rather, the data suggest that the MRX complex is involved in recruiting telomerase activity to yeast telomeres.