Effect of oral administration of 3,3',4,4',5-pentachlorobiphyenl on the intestinal microbiota of Sprague–Dawley rats

The effect of the endocrine-disrupting chemical 3,3',4,4',5-pentachlorobiphyenl (PCB 126) on intestinal microbiota after oral administration, and the improvement of intestinal microbiota and feces quantity by the subsequent administration of Lactobacillus acidophilus or Lactobacillus reuteri was investigated. All the rats were given 100 μg/kg bodyweight of PCB 126. The changes in bacterial counts were confirmed using a culture method. The administration of PCB 126 tended to decrease the bacterial counts of lactobacilli (10^9.6−10^10.2 to 10^8.8−10^9.2) and bifidobacteria (10^5.3−10^6.1 to 10^3.6−10^4.2), and to increase those of Enterobacteriaceae (10^8.2−10^9.1 to 10^9.4−10^10.3) and staphylococci (10^6.6−10^7.4 to 10^7.2−10^8.4) compared to no PCB 126 administration. After administration of PCB 126, L. acidophilus or L. reuteri orally administered to rats caused Enterobacteriaceae and staphylococci counts to decrease, suggesting that the intestinal microbiota was improved by the lactobacilli. The administration of L. acidophilus and L. reuteri improved the balance of intestinal microbiota, and defecation volume returned to its normal level. L. acidophilus and L. reuteri have a remedial effect on intestinal microbiota affected by PCB 126 and can function to lessen accumulated PCB 126 volume.     

Evidence of a local spawning site of marine eels along northeastern Japan, based on the distribution of small leptocephali

Evidence of recent spawning by several species of marine eels of the families Congridae, Ophichthidae, and Nettastomatidae was found over the continental shelf along the coast of northeastern Japan in October 2003. Sixty‐three leptocephali of at least three taxa that ranged from 3.8 to 12.3 mm total length were collected in a relatively small area, just to the south of Cape Shioya, primarily over the 100‐and 200‐m‐depth contours. The leptocephali of Gnathophis nystromi nystromi were the most abundant, followed by those of G. nystromi ginanago. This spawning area is located in an area that appeared to include water originating from the Tsugaru Warm Current and is further south than the typical latitude of the cold water of the Oyashio First Intrusion. These findings suggest that some species of marine eels may not migrate past the slope to spawn, and that the oceanographic features of the region may provide favorable conditions for the growth and retention of leptocephali in the area to the south of Cape Shioya.     

Suppression of Progesterone-enhanced Hyperactivation in Hamster Spermatozoa by γ-aminobutyric Acid

It has been recently shown that mammalian spermatozoa were hyperactivated by steroids, amines and amino acids. In the present study, we investigated whether hyperactivation of hamster sperm is regulated by progesterone (P) and γ-aminobutyric acid (GABA). Although sperm hyperactivation was enhanced by P, GABA significantly suppressed P-enhanced hyperactivation in a dose-dependent manner. Suppression of P-enhanced hyperactivation by GABA was significantly inhibited by an antagonist of the GABA_A receptor (bicuculline). Moreover, P bound to the sperm head, and this binding was decreased by GABA. Because the concentrations of GABA and P change in association with the estrous cycle, these results suggest that GABA and P competitively regulate the enhancement of hyperactivation through the GABA_A receptor.     

Effects of cloud,atmospheric water vapor,and dust on photosynthetically active radiation and total solar radiation in a Mongolian grassland

Photosynthetically active radiation(PAR) is an important input parameter for estimating plant productivity due to its key role in the growth and development of plants.However,a worldwide routine network for systematic PAR measurements is not yet established,and PAR is often calculated as a constant fraction of total solar radiation(SR).Although the ratio of PAR to SR(PAR/SR) has been reported from many places,few studies have been performed for dry regions.The present study was therefore carried out in an arid region of Mongolia to obtain PAR/SR and examine its dependency on sky clearness(the clearness index),water vapor in the atmosphere and aeolian dust.Continuous measurements of PAR and SR were taken every one second using quantum and pyranometer sensors,respectively,and the readings were averaged and recorded at intervals of 30 minutes for a period of 12 months.The lowest monthly mean daily PAR/SR occurred in April(0.420),while the highest ratio was observed in July(0.459).Mean daily PAR/SR during plant growing season(May August) was estimated to be 0.442,which could be useful for modeling plant productivity in the study area.The annual mean daily PAR/SR(0.435) was lower than the values reported in many previous studies.This difference could be explained with the regional variation in climate:i.e.drier climatic condition in the study area.PAR/SR was negatively correlated with the clearness index(r=-0.36,P<0.001),but positively with atmospheric water vapor pressure(r=0.47,P<0.001).The average PAR/SR was significantly lower(P=0.02) on the dusty days compared to the non-dust days.Water vapor in the atmosphere was shown to be the strongest factor in the variation of PAR/SR.This is the first study examining PAR/SR under a semi-arid condition in Mongolia.     

Effect of the amelioration of soil acidity and continuous cropping of cruciferous vegetables on the incidence of clubroot disease and resting spore density in soil

pp. 891–896
In order to elucidate the effect of converter furnace slag applied as a liming amendment and continuous cropping of Qing gin cai ( Brassicae chinensis L.) or leaf daikon ( Raphanus sativus ) on the incidence of clubroot disease and the resting spore density in soil, pot cultivation tests were carried out. In the pot tests, pH(H₂O) was 5.2–6.1 in the non-application pot, and 7.1–7.6 in the pots receiving an application of converter furnace slag.
A significant incidence of club-root disease was apparent in the non-application pots of Qing gin cai . The resting spore density in the soils decreased soon after harvesting, but then increased after mixing the infected roots and soils.
On the other hand, the incidence of the disease was suppressed significantly, in application pots of continuously cropped Qing gin cai . Furthermore, the resting spore density in these soils decreased with repeated cultivation.
These results agreed well with the results from field cultivation tests that the authors have already reported. Macfarlane has reported that the suppression mechanism of clubroot disease brought about by the amelioration of soil acidity is effected through the inhibition of resting spore germination.
In this study, the decrease of resting spores density was associated with the cultivation of Qing gin cai under conditions of high soil pH. From these results, it is concluded that the suppression mechanism is caused by some phenomenon that occurs after the primary zoospore is infected with the root hair.
Until now, avoidance of continuous cropping of susceptible cruciferous vegetables was promoted as one of the most fundamental countermeasures for the control of clubroot disease. However, continuous cropping of suceptible cruciferous vegetables will be a useful technique to decrease resting density specifically under conditions of high soil pH.     

Effects of intramuscular fat deposition on the beef traits of Japanese Black steers (Wagyu)

Effects of intramuscular fat deposition on the chemical composition, tenderness, and free amino acids (FAA) concentration of beef were studied using various classified carcasses of 21 Japanese Black (Wagyu) steers. The Beef Marbling Standard (BMS) No., judged on the market in 1998, and fat content, ranged from 2 to 10 and 4.8 to 39.0% in the M. longissimus thoracis, respectively. Moisture content was negatively correlated with the fat content (r =?0.98, P < 0.01). In contrast, protein content was relatively constant up to approximately 23% fat, corresponding to BMS No.4, and decreased as the fat content increased. Cooking loss was also constant up to approximately 28% fat, corresponding to BMS No.4, and markedly decreased with fat content increase. The beef in these cases were, however, classified into BMS No. around 9 and 11, respectively, according to the BMS model in 1988. A negative correlation was found between the shear‐force value and the fat content (r =?0.83, P < 0.05). Most FAA concentrations on the wet weight of meat were correlated negatively with the fat content, except glutamine, and this negative relationship was still observed when the concentrations were recalculated on the basis of protein. These results indicate that higher marbling Wagyu beef (above approx. 23% fat) would have an extremely lower content of protein, which would partly explain the lower cooking loss and FAA with fat increase. In addition, some other reasons not relating to protein content (e.g. high fat content preventing the breakdown of protein to FAA) seem to explain the negative correlation between fat and FAA.