Effects of the Parasitic Copepod Cardiodectes medusaeus on the Lanternfishes Diaphus theta and Tarletonbeania crenularis off Central California

In two distinct survey areas, offshore from the Farallon Islands and in the vicinity of Pioneer Canyon off central California, Diaphus theta was significantly more prone to infection by the parasitic copepod Cardiodectes medusaeus than Tarletonbeania crenularis. In addition, D. theta was more heavily parasitized in the Pioneer Canyon area than in the Farallon Islands area. A linear relationship was shown between log_e-transformed otolith size and log_e-transformed SL and between log_e-transformed dry weight and log_e-transformed SL for D. theta and T. crenularis in both survey areas. A test of slopes showed differences between the two survey areas for both species. Lower dry weights were observed for both D. theta and T. crenularis, in parasitized versus non-parasitized specimens in the Pioneer Canyon area. In the Farallon Islands area, however, no differences were observed. Larger otolith sizes were observed in parasitized D. theta versus non-parasitized specimens in the Pioneer Canyon area, while no differences were observed in the Farallon Islands area. In contrast, T. crenularis had larger otolith sizes in parasitized versus non-parasitized specimens in the Farallon Islands area, while no significant differences were observed in the Pioneer Canyon area. These findings provided evidence of geographic and interspecific variability in both the prevalence and the physiological effects of parasitism.     

The adaptive response of MyoD family proteins in overloaded, regenerating and denervated rat muscles.

Using Western blot analysis, we investigated whether the amount of myogenic regulatory factors differs in slow-type and fast-type muscles. In addition, we examined the adaptive response of myogenic regulatory factor protein in the overloaded rat muscles by the ablation of synergists, in the regenerating muscles following bupivacaine injection and in the denervated muscle. The amount of myogenin protein in the slow-type muscle was markedly greater. In contrast, the proteins MyoD and Myf-5 were selectively accumulated in the fast-type muscles. A gradual down-regulation of MyoD and Myf-5 proteins was detected in the denervated fast-type muscles, but not in the myogenin protein content. A rapid down-regulation of myogenic regulatory factor protein was observed both of the mechanically overloaded and in the regenerating muscles. These results indicate that the fast-type-specific gene expression in muscle is modulated by MyoD and Myf-5 proteins and suggest that myogenin protein plays an important role in the reconstruction of damaged neuromuscular connections.     

Existence of acyl-CoA hydrolase-mediated pathway supplying arachidonic acid for prostaglandin synthesis in microsomes from rabbit kidney medulla.

We have previously shown that acyl-coenzyme A (CoA) hydrolase that hydrolyzes arachidonoyl-CoA (AA-CoA) to arachidonic acid (AA) and CoA is present in the cytosol of rabbit kidney medulla and that this enzyme can supply AA for prostaglandin (PG) synthesis in this region. In the present study, the existence of the acyl-CoA hydrolase-mediated pathway that supplies AA available for PG synthesis in microsomes from the kidney medulla was examined. AA-CoA (20 microM) was preincubated with the 105,000 g pellet (microsomes, 0.5 mg of protein) from the medulla for 5 min at 37 degrees C followed by incubation with the medulla microsomes (0.5 mg of protein) (the source of PG synthesizing enzymes) in the presence of hydroquinone and reduced glutathione for 5 min at 37 degrees C. The PGs formed were measured by high-pressure liquid chromatography using 9-anthryldiazomethane for derivatization. The addition of the microsomal fraction from the medulla in the preincubation mixture increased total PG formation from 3.86 to 8.70 nmol, and this stimulatory effect was somewhat weaker than that of the cytosolic fraction. On the other hand, the microsomal fraction in the kidney cortex has an extremely lower capacity to supply AA for PG synthesis than do medulla microsomes. These results suggest that, in kidney medulla, the microsomes as well as the cytosol have the potential route that supplies AA from AA-CoA for PG synthesis and that this pathway is mediated by acyl-CoA hydrolase.     

Behavioral and biochemical changes following acute administration of MPTP and MPP+

The acute effects of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and 1-methyl-4-phenylpyridinium ion (MPP+) on mouse locomotor activity and striatal dopamine (DA) and 5-hydroxytryptamine (5-HT) levels were investigated. A single dose of either MPTP (10-30 mg/kg, i.p.) or MPP+ (5-20 ug/mouse, i.c.v.) decreased locomotor activity 10-40 min after injection: this locomotor effect was significantly suppressed by either pretreatment with nomifensine or 1-deprenyl alone, or by the combination of desmethylimipramine and 6-hydroxydopamine. Pretreatment with clorgyline did not suppress this behavior and a single dose of haloperidol enhanced the effect. The striatal levels of DA, 3-methoxytyramine and 5-HT increased in parallel with the decrease in locomotor activity caused by MPTP or MPP+. In contrast, levels of 3,4-dihydroxyphenylacetic acid, homovanillic acid and 5-hydroxyindoleacetic acid were decreased by injection of either MPTP or MPP+. Possible mechanism(s) of the behavioral and biochemical changes caused by the acute actions of MPTP and MPP+ with respect to their neurotoxic effects on the nigrostriatal DA system are discussed.     

Rapid antibody selection by mRNA display on a microfluidic chip

In vitro antibody-display technologies are powerful approaches for isolating monoclonal antibodies from recombinant antibody libraries. However, these display techniques require several rounds of affinity selection which is time-consuming. Here, we combined mRNA display with a microfluidic system for in vitro selection and evolution of antibodies and achieved ultrahigh enrichment efficiency of 10⁶- to 10⁸-fold per round. After only one or two rounds of selection, antibodies with high affinity and specificity were obtained from naïve and randomized single-chain Fv libraries of ~10¹² molecules. Furthermore, we confirmed that not only protein–protein (antigen–antibody) interactions, but also protein–DNA and protein–drug interactions were selected with ultrahigh efficiencies. This method will facilitate high-throughput preparation of antibodies and identification of protein interactions in proteomic and therapeutic fields.