Gustatory responses in Pacific bluefin tuna Thunnus orientalis (Temminck and Schlegel)

Gustatory neural responses of the Pacific bluefin tuna Thunnus orientalis (Temminck and Schlegel) to extracted compounds of prey organisms, such as amino acids, nucleotide‐related substances, organic acids and organic bases, were electrophysiologically recorded from the facial nerve supplying the anterior palate. Of the 17 amino acids tested, l ‐proline was the most potent amino acid at 10^?2 M, and its threshold was the lowest at around 10^?6 M. l ‐leucine, l ‐methionine, l ‐alanine, l ‐valine and l ‐isoleucine were also highly stimulatory at 10^?2 M; however, the other 11 amino acids examined were not as effective or were ineffective. Thus, the gustatory receptors for amino acids of the Pacific bluefin tuna show a narrowly tuned response profile. Among the seven nucleotide‐related substances tested, uridine‐5′‐monophosphate, inosine‐5′‐monophosphate and adenosine‐5′‐diphosphate were highly stimulatory, and their thresholds were 10^?4–10^?5 M. Inosine elicited a positive response at 10^?2 M but its response magnitude was not so high. Organic acids l ‐lactic and pyruvic acids were effective at 10^?2 M, but no response was elicited at 10^?3 M. Among organic bases, betaine was highly stimulatory, and its response magnitude at 10^?2 M is almost equal to that of l ‐proline at the same concentration. The threshold for betaine was determined to be at around 10^?5 M. Trimethylamine oxide and ammonium chloride were ineffective.     

Effects of dietary supplementation with feeding stimulants on yellowtail Seriola quinqueradiata (Temminck & Schlegel; Carangidae) protein digestion at low water temperatures

Feeding trials were carried out to examine substances that could be used as supplements in low‐protein/high‐lipid diets to improve protein digestion of yellowtails (Seriola quinqueradiata) during winter. Dietary supplementation with synthetic or natural (krill and squid extracts) feeding stimulants (FS) improved feed intake and growth performance of yellowtails. Moreover, the apparent protein digestibility (APD) and pepsin, trypsin and chymotrypsin secretions in fish fed diets supplemented with the different FS were superior to those in fish fed the control diet. These findings suggest that the dietary inclusion of either synthetic or natural FS is a potential tool for improving protein digestion at low water temperatures, and may provide a promising solution for the winter growth retardation experienced in yellowtail culture.     

A Case Study on Estimation of Dry Deposition of Sulfur and Nitrogen Compounds by Inferential Method

In order to estimate dry deposition, deposition velocity calculation and concentration measurement were carried out in Niigata, Japan. Deposition velocities of SO₂ and HNO₃ for some surfaces such as coniferous forest, deciduous forest, agricultural land, and water were calculated taking into account diurnal variations of meteorological elements using routine meteorological data. Deposition velocities of fine and coarse aerosols were also estimated respectively. Concentrations of SO₂, HNO₃, sulfate and nitrate in fine and coarse aerosols respectively were measured from July to December in 1998 using filter pack and denuder methods. The results indicate that HNO₃ dry deposition for the high aerodynamic roughness surfaces such as forests is quite large. It is suggested that sulfate and nitrate aerosols depositions as well as the gases depositions should be taken into account to estimate dry deposition of sulfur and nitrogen compounds. It is also indicated that dry depositions of sulfur and nitrogen compounds are unable to ignore compared with their wet depositions.     

Effects of high ambient temperature on urea‐nitrogen recycling in lactating dairy cows

Effects of exposure to hot environment on urea metabolism were studied in lactating Holstein cows. Four cows were fed ad libitum a total mixed ration and housed in a temperature‐controlled chamber at constant moderate (18°C) or high (28°C) ambient temperatures in a cross‐over design. Urea nitrogen (N) kinetics was measured by determining urea isotopomer in urine after single injection of [¹⁵N₂]urea into the jugular vein. Both dry matter intake and milk yield were decreased under high ambient temperature. Intakes of total N and digestible N were decreased under high ambient temperature but urinary urea‐N excretion was increased. The ratio of urea‐N production to digestible N was increased, whereas the proportion of gut urea‐N entry to urea‐N production tended to be decreased under high ambient temperature. Neither return to the ornithine cycle, anabolic use nor fecal excretion of urea‐N recycled to the gut was affected by ambient temperature. Under high ambient temperature, renal clearance of plasma urea was not affected but the gut clearance was decreased. Increase of urea‐N production and reduction of gut urea‐N entry, in relative terms, were associated with increased urinary urea‐N excretion of lactating dairy cows in higher thermal environments.     

Demonstration of bovine herpesvirus type 1 and Mannheimia haemolytica antigens in specimens stored for up to 22 months in buffered formalin

Bovine herpesvirus type 1 (BHV-1) and Mannheimia haemolytica antigens were demonstrated in lung tissues that were stored in 10% neutral phosphate buffered formalin for 1 to 22 months using the immunoperoxidase method. There were no differences observed in terms of labelling intensity and distribution of M. haemolytica antigens between specimens stored for 1 and 22 months. The labeling intensity in sections from 2-cm thick specimens was comparable to those from 0.2-cm thick specimens. There was no difference observed between pronase-treated and -untreated sections. However, for BHV-1, the labeling intensity in untreated sections was reduced in tissues that had been stored from 12 to 22 months. Sections from thin specimens stored in neutral buffered formalin for 22 months exhibited a stronger staining intensity than those from thick specimens.     

EDEM as an acceptor of terminally misfolded glycoproteins released from calnexin

Terminally misfolded proteins in the endoplasmic reticulum (ER) are retrotranslocated to the cytoplasm and degraded by proteasomes through a mechanism known as ER-associated degradation (ERAD). EDEM, a postulated Man8B-binding protein, accelerates the degradation of misfolded proteins in the ER. Here, EDEM was shown to interact with calnexin, but not with calreticulin, through its transmembrane region. Both binding of substrates to calnexin and their release from calnexin were required for ERAD to occur. Overexpression of EDEM accelerated ERAD by promoting the release of terminally misfolded proteins from calnexin. Thus, EDEM appeared to function in the ERAD pathway by accepting substrates from calnexin.     

Production of Diabetic Offspring Using Cryopreserved Epididymal Sperm by In Vitro Fertilization and Intrafallopian Insemination Techniques in Transgenic Pigs

Somatic cell nuclear transfer (SCNT) is a useful technique for creating pig strains that model human diseases. However, production of numerous cloned disease model pigs by SCNT for large-scale experiments is impractical due to its complexity and inefficiency. In the present study, we aimed to establish an efficient procedure for proliferating the diabetes model pig carrying the mutant human hepatocyte nuclear factor-1α gene. A founder diabetes transgenic cloned pig was generated by SCNT and treated with insulin to allow for normal growth to maturity, at which point epididymal sperm could be collected for cryopreservation. In vitro fertilization and intrafallopian insemination using the cryopreserved epididymal sperm resulted in diabetes model transgenic offspring. These results suggest that artificial reproductive technology using cryopreserved epididymal sperm could be a practical option for proliferation of genetically modified disease model pigs.     

Resistance to paraquat in Mazus pumilus

Mazus pumilus is an annual self‐pollinating weed that is commonly found in arable land, vegetable gardens and roadsides. This weed harbours insects and pathogens that attack vegetables. The mechanism of resistance to paraquat of M. pumilus found in Ohita, Japan, was studied. Whole plant bioassays revealed that the resistant (R) biotypes were four to six times less susceptible than controls. Chlorophyll destruction of leaf discs by paraquat treatment in R biotypes was 4–20 times lower than those of susceptible (S) biotypes. Ferric reducing antioxidant power (FRAP) values in R biotypes were higher than those of S biotypes before and after paraquat treatments. The activity of superoxide dismutase (SOD) was also higher in R biotypes than those of S biotypes before and after treatment with paraquat, but the activities of ascorbate peroxidase (APX) and catalase (CAT) were not different between R and S biotypes. Change of ascorbate (AsA) contents before and after paraquat treatment was equivalent in both biotypes. These results indicate that the increased SOD activity and antioxidant capacity in R biotypes contribute to the resistance to paraquat of M. pumilus.