Low frequency fatigue in human quadriceps is fatigue dependent and not task dependent.

It is well accepted that a low intensity/long duration isometric contraction induces more low frequency fatigue (LFF) compared to a high-intensity/short-duration contraction. However, previous reports examined the intensity/duration of the contraction but did not control the level of fatigue when concluding fatigue is task dependent. The purpose of this study was to determine whether a long duration/low intensity fatiguing contraction would induce greater LFF than a short duration/high-intensity contraction when the quadriceps muscle was fatigued to similar levels. Eighteen healthy male subjects performed quadriceps contractions sustained at 35% and 65% of maximal voluntary contraction (MVC) on separate days, until the tasks induced a similar amount of fatigue (force generating capacity=45% MVC). Double pulse torque to single pulse torque ratio (D/S ratio) was obtained before, immediately and 5min after fatigue along with the electromyographic (EMG) signal from vastus medialis (VM) and rectus femoris (RF). The D/S ratio significantly (p<0.05) increased by 8.7+/-8.5% (mean+/-SD) and 10.2+/-9.2% after 35% and 65% tasks, respectively, and remained elevated 5min into recovery; however, there was no significant difference in ratio between the two sessions immediately or 5min post-fatigue (p>0.05) even though the endurance time for the 35% fatigue task (124+/-39.68s) was significantly longer (p=0.05) than that of the 65% task (63+/-17.73s). EMG amplitude and median power frequency (MPF) analysis also did not reveal any significant differences between these two sessions after fatigue. These findings indicate that LFF fatigue is fatigue dependent as well as task intensity/duration dependent. These findings assist us in understanding task dependency and muscle fatigue.     

Effects of temperature on metabolism, growth and growth efficiency of Thysanoessa longipes (Crustacea: Euphausiacea) in the Japan Sea

Growth (assessed from intermolt period and molt increment) andmetabolism (oxygen consumption) of juvenile and adult Thysanoessalongipes from central Japan Sea were determined at eight differenttemperatures ranging from 0 to 14°C. The intermolt periodshortened progressively as temperature increased from 0 to 14°C.The molt increment was not assessed satisfactorily in the rearingexperiments, and therefore this was estimated from the naturalgrowth curve and habitat temperature, combined with laboratory-obtainedintermolt data. Oxygen consumption rates increased exponentiallyfrom 0 to 8°C and then leveled off. From these results,the growth was expressed as a function of temperature and bodysize and metabolism as a function of temperature. Because ofthe differential effects of temperature on growth and metabolism,the net growth efficiency [NGE: 100 x growth/(growth + metabolism)]changed with temperature. The temperature at which T. longipesattained maximum NGE varied from 0 to 8°C, depending onthe body length of specimens of 5, 10, 15 and 20 mm. The presentresults are compared with our previous data on Euphausia pacificain relation to the body composition and habitat usage of thesetwo trophically important species in the food web of the JapanSea.     

Ultra-high field NMR studies of antibody binding and site-specific phosphorylation of alpha-synuclein

Although biological importance of intrinsically disordered proteins is becoming recognized, NMR analyses of this class of proteins remain as tasks with more challenge because of poor chemical shift dispersion. It is expected that ultra-high field NMR spectroscopy offers improved resolution to cope with this difficulty. Here, we report an ultra-high field NMR study of alpha-synuclein, an intrinsically disordered protein identified as the major component of the Lewy bodies. Based on NMR spectral data collected at a 920 MHz proton frequency, we performed epitope mapping of an anti-alpha-synuclein monoclonal antibody, and furthermore, characterized conformational effects of phosphorylation at Ser129 of alpha-synuclein.     

A HMG-CoA reductase inhibitor improved regression of atherosclerosis in the rabbit aorta without affecting serum lipid levels: possible relevance of up-regulation of endothelial NO synthase mRNA.

We determined the role of Fluvastatin: HMG-CoA reductase inhibitor on the regression of atherosclerosis following removal of dietary cholesterol. Male rabbits fed a 0.5% cholesterol diet for 12 weeks were divided into three groups: A1, hypercholesterolemic; A2, fed a regular diet for an 12 additional weeks; and A3, fed a regular diet with fluvastatin (2 mg/kg/day). Fluvastatin treatment (A3) did not affect serum lipid levels compared with A2. However, it decreased the atherosclerotic area in the aortic arch and decreased total and esterified cholesterol concentrations in the descending aorta. Tone-related basal NO release in the thoracic aorta was larger in A3 than in A2. eNOS mRNA in vessel was determined by competitive RT-PCR assay. It increased in A1, compared with normal aorta and decreased in A2; however, it did not decrease in A3. This is the first report of a decrease in eNOS mRNA in atherosclerosis after removal of dietary cholesterol and a reversal of it by a HMG-CoA reductase inhibitor, which may contribute to the regression of atherosclerosis.     

Genetic structure of Pacific crown-of-thorns starfish (Acanthaster cf. solaris) in southern Japan based on genome-wide RADseq analysis

Coral Reefs - Pacific crown-of-thorns starfish (Acanthaster cf. solaris) are known to be widely distributed, and previous studies (showing limited genetic structure) suggest that there are high...     

Distribution of pink-pigmented facultative methylotrophs on leaves of vegetables

The distribution of pink-pigmented facultative methylotrophs (PPFMs) on the leaves of various vegetables was studied. All kinds of vegetable leaves tested gave pink-pigmented colonies on agar plates containing methanol as sole carbon source. The numbers of PPFMs on the leaves, colony-forming units (CFU)/g of fresh leaves, differed among the plants, although they were planted and grown at the same farm. Commercial green perilla, Perilla frutescens viridis (Makino) Makino, gave the highest counts of PPFMs (2.0-4.1×10(7) CFU/g) of all the commercial vegetable leaves tested, amounting to 15% of total microbes on the leaves. The PPFMs isolated from seeds of two varieties of perilla, the red and green varieties, exhibited high sequence similarity as to the 16S rRNA gene to two different Methylobacterium species, M. fujisawaense DSM5686(T) and M. radiotolerans JCM2831(T) respectively, suggesting that there is specific interaction between perilla and the PPFMs.     

Evidence for secretion of 7B2 by A- and B-cells of hamster pancreatic islets.

7B2 is a neuroendocrine protein, and in the pancreatic islets the presence of 7B2 in A- and B-cells was immunohistochemically demonstrated. In order to examine 7B2 secretion by A- and B-cells of pancreatic islets, we prepared isolated hamster pancreatic islet cells as well as an A-cell-rich culture, and studied 7B2 secretion under certain stimulations. 7B2 was secreted by isolated hamster pancreatic islet cells. This secretion was stimulated by theophylline and arginine, but glucose had a weak effect on the 7B2 secretion. Such a response of 7B2 to the stimulations was different from that of insulin or glucagon. 7B2 secretion was also noted in the A-cell-rich culture. These results suggest that 7B2 is secreted by both A- and B-cells of the hamster pancreatic islets and its secretion is regulated under certain conditions.     

The ecological impact of an introduced population on a native population in the firefly Luciola cruciata (Coleoptera: Lampyridae)

In Japan, Tatsuno Town has been famous for many Luciola cruciata fireflies emerging every summer at least since the 1920s. However, in the 1960s, L. cruciata fireflies were intentionally introduced from the Lake Biwa area into Matsuo-kyo, the most famous habitat of fireflies in that town. In this study, I examined ambient temperatures and flash rates of L. cruciata at four sites including Matsuo-kyo in the Tatsuno area and two sites in the Lake Biwa area. The linear regression of flash rates on temperatures indicated that the Matsuo-kyo population was distinct from the other three populations native to the Tatsuno area, but similar to the two populations native to the Lake Biwa area in terms of flash rates. These results were also supported by a recent molecular biological study, suggesting that the introduced fireflies had a strong ecological impact on the native ones at Matsuo-kyo. The present study emphasizes that we should not transport and release L. cruciata fireflies without careful consideration.