Annual changes in the hatching period of the dominant cohort of larval and juvenile ayu Plecoglossus altivelis altivelis in the Shimanto Estuary and adjacent coastal waters during 1986–2001

ABSTRACT:   Larval and juvenile ayu from seven year-groups (1986, 1987, 1992, 1995, 1996, 1999 and 2000) were collected in the Shimanto Estuary and adjacent coastal waters. The present study focuses on the variation among year-groups in the hatching period estimated by age determination using the otolith. The hatching period of the dominant cohorts in the 1986, 1987 and 1992 year-groups occurred from late October to mid-November. A delay of the hatching period of the dominant cohort was observed from the 1995 year-group, which occurred in late November to early December, and the dominant periods in the 1996, 1999 and 2000 year-groups were observed from early to late December. It appears that the delay of the hatching period of dominant cohorts was not due to a delay of spawning, but a high mortality of early hatched larvae. The water temperature in autumn in the coastal waters adjacent to the Shimanto River has tended to rise over the past 20 years and this trend was especially notable in the late 1990s. The delay in the hatching period of the dominant cohort observed from the 1995 year-group was likely to be related to the rise in seawater temperatures in autumn.     

Cytotoxic constituents in the holdfast of cultivated Laminaria japonica

ABSTRACT:     Four steroidal ketones were isolated from the holdfast of cultivated Laminaria japonica . The structures were characterized as ergosta-4,24(28)-diene-3-one (1), ergosta-4,24(28)-diene-3,6-dione (2), stigmasta-4,24(28)-diene-3-one (3) and stigmasta-4,24(28)-diene-3,6-dione (4), by spectral data. Compounds 2 and 4 were shown to be cytotoxic against the MCF-7 human breast cancer cell, and the growth of MCF-7 was inhibited by 96% and 79%, respectively, at 10 µg/mL. It is the first report on the isolation of cytotoxic steroidal ketones from the kelp in the genus of Laminaria.     

Quantitative real‐time PCR monitoring of Escherichia coli and Clostridium perfringens with oral administration of Lactobacillus plantarum strain Lq80 to weaning piglets

Levels of fecal or intestinal lactobacilli, Escherichia coli and Clostridium perfringens, and the prevalence of clostridial alpha toxin gene and heat‐stable toxin (ST) gene of enterotoxigenic E. coli (ETEC) were monitored in weaned piglets before (day 0) and during (days 7, 14, and 21) the administration of Lactobacillus plantarum strain Lq80. Lactobacilli were enumerated in a culture‐dependent method. The remainders were determined by quantitative real‐time PCR. In this quantitative real‐time PCR method, the detection limit was proved to be as low as 10³ cells/g feces or intestinal contents. Number of lactobacilli increased from day 0 to day 7 (P < 0.05), to day 14 (P < 0.05), and to day 21 (P = 0.07) in the Lq80‐administered group. L. plantarum contributed to as low as 10% of the lactobacillal population in the Lq80‐administered group. The number of E. coli and C. perfringens, and the prevalence of alpha toxin gene in feces or intestinal contents of the Lq80‐administered group decreased, at least in the first week of the postweaning period. Oral administration of L. plantarum strain Lq80 can stimulate the growth of indigenous lactobacilli and decrease ST‐producing ETEC and C. perfringens in the intestine of postweaning piglets.     

Complete Nucleotide Sequence of Ryegrass Mottle Virus : A New Species of the Genus Sobemovirus

The genome of Ryegrass mottle virus (RGMoV) comprises 4210 nucleotides. The genomic RNA contains four open reading frames (ORFs). The largest ORF 2 encodes a polyprotein of 947 amino acids (103.6 kDa), which codes for a serine protease and an RNA-dependent RNA polymerase. The viral coat protein is encoded on ORF 4 present at the 3′-proximal region. Other ORFs 1 and 3 encode the predicted 14.6 kDa and 19.8 kDa proteins of unknown function. The consensus signal for frameshifting, heptanucleotide UUUAAAC and a stem-loop structure just downstream is in front of the AUG codon of ORF 3. Analysis of the in vitro translation products of RGMoV RNA suggests that the 68 kDa protein may represent a fusion protein of ORF 2-ORF 3 produced by frameshifting. The protease region of the polyprotein and coat protein have a low similarity with that of the sobemoviruses (approximately 25% amino acid identity), while the RNA-dependent RNA polymerase region has particularly strong similarity (54 to 60% of more than 350 amino acid residues). The sequence similarities of RGMoV to the sobemoviruses, together with the characteristic genome organization indicate that RGMoV is a new species of the genus Sobemovirus. Received 28 June 2000/ Accepted in revised form 14 November 2000     

Vitrification for bovine embryos with low‐quality grade

This study was conducted to examine the utility of vitrification for bovine embryos with low‐quality grade, and simple cryoprotectants dilution method for practitioners. In Experiment 1, survival of frozen embryos was compared with that of vitrified embryos using minimum volume cooling (MVC). Then, vitrified embryos were used to confirm the optimum sucrose concentration in Experiment 2. The survival rates of embryos that had been vitrified following diluted cryoprotectants with the one‐step in‐straw method were compared with those of fresh control embryos in Experiment 3. Frozen‐thawed or vitrified‐warmed blastocysts were cultured with TCM‐199 supplemented with 100 μmol/L beta‐mercaptoethanol +5% fetal bovine serum at 38.5°C in an atmosphere of 5% CO₂ in air, their survival after 24 hr were compared. The development to term of fair quality in vivo embryos after vitrification was examined in Experiment 4. Results show that survival rates of frozen‐thawed embryos were lower (p < .05) than that of vitrified‐warmed ones. When vitrified embryos were warmed in 0.3 mol/L sucrose in straws, their survival rate was 100%. The total cell numbers of vitrified‐warmed embryos were comparable to those of fresh control embryos. The six calves from 13 vitrified embryos were delivered in Experiment 4. These results indicate that MVC vitrification following one‐step cryoprotectants dilution is utilized to preserve low‐quality bovine embryos.     

Effect of feeding non-fibrous carbohydrate before grazing on intake and nitrogen utilization in dairy cows throughout the grazing season

Ten lactating cows were used to determine the effect of feeding non-fibrous carbohydrate (NFC) supplement before grazing on feed intake and nitrogen (N) utilization throughout a grazing season. The experiment was conducted from June to September. Cows grazed twice a day (2.5 h × 2) under a set stocking system and were fed NFC supplement (1 kg/4 kg of milk yield) 2 h before grazing (PRE) or immediately after grazing (POST). Cows were also fed a grass and corn silage mixture ad libitum. Herbage dry matter intake (DMI) was greater for PRE than for POST throughout the experiment and decreased from June to September. Conversely, silage DMI was less for PRE than for POST throughout the experiment and increased over the grazing season. Consequently, total DMI for PRE did not differ from that for POST. Milk urea-N concentration and urinary urea-N excretion in June did not differ between the treatments, whereas that after July was higher for PRE than for POST. Proportion of urinary N excretion to absorbed N intake in June was lower for PRE than for POST, but that after July was higher for PRE than for POST. Feeding NFC supplement before grazing would improve N utilization when cows eat large amounts of herbage high in N.     

Control of tomato bacterial wilt and root-knot diseases by Bacillus thuringiensis CR-371 and Streptomyces avermectinius NBRC14893

Ralstonia solanacearum and Meloidogyne incognita are two soilborne pathogens that cause serious damage and great losses in the production of tomato. For this purpose, a bacterial isolate, Bacillus thuringiensis CR-371, and an actinomyces isolate, Streptomyces avermectinius NBRC14893, were examined for their ability to protect tomato from root-knot nematode and bacterial wilt diseases under glasshouse conditions. Treatment of tomato roots with B. thuringiensis CR-371 and S. avermectinius NBRC14893 followed by challenge inoculation with R. solanacearum and M. incognita significantly decreased disease severity of bacterial wilt alone, root-knot nematode alone, or mixed infection by both pathogens compared to the control. Furthermore, pretreatment of tomato roots with B. thuringiensis CR-371 and S. avermectinius NBRC14893 significantly reduced bacterial proliferation of R. solanacearum both in pathogen alone inoculated plants and in plants co-inoculated with R. solanacearum and M. incognita. In conclusion, our results suggest that the treatment of tomato roots with B. thuringiensis CR-371 and S. avermectinius NBRC14893 simultaneously suppresses bacterial wilt and root-knot nematode diseases. Therefore, B. thuringiensis CR-371 and S. avermectinius NBRC14893 could provide new options for integrated pest management strategies against plant diseases, especially against bacterial-nematode disease complexes that cause synergistic yield losses.     

略谈中日林业发展的道路与合作潜能

为了回顾过去，把握未来，中文简单回顾和比较了中日两国林业发展的道路的各自长短，并为加强合作的必要性和可能性提出了一些直观的看法。     

Expression of genes encoding inflammasome sensor subunits in the duodenal and colonic mucosae of dogs with chronic enteropathy

Inflammasomes play a pivotal role in gastrointestinal homeostasis and inflammation. However, it remains elusive whether the nucleotide-binding oligomerization domain-like receptor (NLR) family inflammasomes, such as NLR family pyrin domain-containing (NLRP) 3, NLRP6, and NLRP12, are involved in the pathogenesis of canine chronic enteropathy (CE), which includes antibiotic-responsive enteropathy (ARE), food-responsive enteropathy (FRE), immunosuppressant-responsive enteropathy (IRE), and non-responsive enteropathy (NRE). Thus, we measured mRNA expression of NLRP3, NLRP6, and NLRP12 in the intestinal mucosa of 35 dogs with CE (ARE, four dogs; FRE, 11 dogs; IRE and NRE, 20 dogs) and seven healthy dogs. As per real-time PCR analysis, significant increases in mRNA expression of NLRP3 and NLRP12 were noted in the colonic but not in the duodenal mucosa of dogs with FRE compared to healthy dogs. These findings suggested that the NLRP3 and NLRP12 inflammasomes might contribute to the development of colitis in dogs with FRE.