Habitat and prey selection of common minke,sei, and Bryde’s whales in mesoscale during summer in the subarctic and transition regions of the western North Pacific

This study represents the first quantitative analysis of the characteristics of the distribution areas and stomach contents of common minke whale Balaenoptera acutorostrata, sei whale B. borealis, and Bryde’s whale B. edeni in relation to oceanographic and prey environments in mid summer in the western North Pacific. Common minke whales were distributed within subarctic regions and the northernmost region of the transitional domain, coinciding with the main habitat of their preferred prey, Pacific saury Cololabis saira. Sei whales were mainly found in the northernmost part of the transition zone and showed prey preference for Japanese anchovy Engraulis japonica, which was significantly more abundant in the main distribution area of the whale than in its adjacent areas. “Hot spots” of Bryde’s whales were found in several regions of the transition zone between the subarctic boundary and the Kuroshio front. This whale species preferred Japanese anchovy as prey, for which the distribution density was significantly higher in the main distribution area of the whale than in the adjacent areas. These results indicate that the summer distributions of Pacific saury and Japanese anchovy greatly influence the distributions of these whale species, suggesting that the whales’ habitat selection is closely related to their prey selection.     

Nursery habitat use for larval and juvenile Pacific herring Clupea pallasii in Miyako Bay on the Pacific coast of northern Japan

Fisheries Science - To clarify nursery habitat use for larval and juvenile Pacific herring Clupea pallasii, we collected eggs, larvae, and juveniles at several sampling sites in inner Miyako Bay...     

CD56 is expressed exclusively on CD3+ T lymphocytes in canine peripheral blood

CD56+ cells in canine blood leukocytes were characterized by flow-cytometric analysis of peripheral blood of 30 healthy adult beagle-dogs (15 males and 15 non-pregnant females). In 19 of the 30 dogs, anti human CD56 antibody, Leu-19, reacted with 8.8-21.7% of peripheral blood lymphocytes. All CD56+ cells simultaneously expressed CD3 molecules on their surface. Further phenotypic analysis revealed that 50.6+/-13.1% of the CD56+ cells showed CD4-CD8+ phenotype and 43.7+/-10.1% showed CD4+CD8- phenotype. Expression intensity of CD56 on the CD4-CD8+CD56+ cells was significantly higher than that on CD4+CD8-CD56+ cells (P<0.001). These findings indicate that CD56, which is a neural cell adhesion molecule, is uniquely expressed on subsets of T lymphocytes in canine peripheral blood.     

High prevalence of Mycoplasma equirhinis in Thoroughbred horses with respiratory symptoms in autumn 2018

Mycoplasma species are often isolated from horses with respiratory symptoms; however, the pathogenicity of Mycoplasma is still unclear. In autumn of 2018, we encountered an increase in cases with respiratory symptoms, mainly coughing, in a group of Thoroughbred racehorses in Japan. We examined tracheal wash samples obtained from 40 of those cases. Bacteria and viruses that commonly cause respiratory symptoms were investigated, and anaerobes were detected in only 5 cases and Streptococcus equi subsp. zooepidemicus (S. zooepidemicus) was detected in only 1 case of 40 cases with loop-mediated isothermal amplification assay. S. zooepidemicus and Streptococcus pneumoniae were isolated at a bacterial count of higher than 1.0 × 10⁴ CFU/ml from 5 and 2 cases of 28 cases cultured, respectively. None of the viruses investigated was detected in 40 cases. Mycoplasma equirhinis (M. equirhinis) was isolated from 40.0% (16/40) of the cases, which was higher than previously reported isolation rates. The rate of M. equirhinis isolation in the cases from 2018 was significantly higher than the isolation rates in the other horses: clinical cases with respiratory symptoms in 2019–2020 (13.6%, 3/22) and healthy horses (13.5%, 5/37) in Japan. In this study, the isolation rate of M. equirhinis from horse group with cough symptoms in 2018 was high and no other common etiological agents were detected. The pathogenesis of M. equirhinis is still unclear, however, M. equirhinis might have been associated with respiratory symptoms in the Thoroughbred horse cases in 2018.     

Effects of nereistoxin on the neuroexcitatory action of insecticides

Nereistoxin suppressed the excitatory actions of α- and γ-BHC and HEOD in the central nervous system of Periplaneta americana (L.). However, it did not affect the neurotoxic action of DDT and DBrDT. Since nereistoxin is an acetylcholine antagonist, it is postulated that BHC and HEOD act to produce high level of acetylcholine and the resulting after-discharges, while DDT and DBrDT seem to attack the noncholinergic region of insect nervous system.     

Quantitative structure-activity studies of substituted benzyl chrysanthemates: 1. Correlations between symptomatic and neurophysiological activities against American cockroaches

A number of substituted benzyl (1R)-trans-chrysanthemates and related compounds were synthesized. Their symptomatic activities in terms of levels which induce convulsions as well as cause death in American cockroaches were determined by injection with and without application of synergists as inhibitors of metabolism. The neuroexcitatory and neuroblocking activities were also determined in terms of minimum effective concentrations to induce repetitive train of impulses and conduction blockage, respectively, to central nerve cords excised from the cockroaches and immersed in Ringer's solution. Correlations between symptomatic and neurophysiological activities were analyzed quantitatively with the aid of molecular hydrophobicity parameter and regression analysis. Each symptomatic activity from which the effect of metabolism is eliminated was found to be analyzable by means of a linear combination of indices for two types of neurophysiological activity when the transport factor is separated by using the hydrophobicity parameter. A closer correlation was found between neuroblocking activity and the “convulsive” effect than between neuroexcitatory activity and the “convulsive” effect, whereas both neurophysiological effects operate together on the cockroaches resulting in paralysis and death.     

Antibodies to Borna disease virus in infected adult rats: an early appearance of anti-p10 antibody and recognition of novel virus-specific proteins in infected animal brain cells

The time course for appearance of antibodies to Borna disease virus (BDV) major antigens, p40, p24, p18 and p10 were investigated in BDV-inoculated adult rats by Western blotting. Anti-p10 antibodies were detected in sera as early as anti-p40 and -p24 antibodies at four or five weeks after inoculation. Furthermore, in addition to these major antigens of BDV, the rat serum could detect additional 80-, 58-, 43-, 20-, and 16-kDa proteins in BDV-infected cultured cells and/or animal brain cells by Western blot analysis. Of these proteins, the 20- and 16-kDa proteins were shown to be related to p24 protein by their reactivity with anti-p24 monoclonal antibody. Interestingly, the 58- and 24-kDa were found only in BDV-infected animal brain cells but not in cultured cells. The results in this study could provide a useful information on the mechanism for the viral replication and pathogenesis.     

Examination of the 16S-23S rRNA intergenic spacer sequences of 'Candidatus Mycoplasma haemobos' and Mycoplasma haemofelis

The intergenic spacer region between the 16S and 23S rRNA genes of mycoplasmas has been used for a genetic marker for identification of the species. Here we show the intergenic spacer regions of two hemotropic mycoplasmas, Mycoplasma haemofelis and 'Candidatus Mycoplasma haemobos (synonym: 'C. M. haemobovis')' are also useful for classification of this particular group of mycoplasms. The spacer region of M. haemofelis and `C. M. haemobos' consisted of 209 and 210 base pairs, respectively, and both lacked the spacer tRNA genes. Phylogenetic analysis suggested a monophyletic relationship among hemoplasmas and M. fastidiosum. A hypothetical secondary structure predicted in the spacer regions tentatively assigned the boxA and boxB motifs peculiar to the members of the genus Mycoplasma. M. haemofelis and 'C. M. haemobos' possessed a stem-loop structure in common, despite the presence of a palindromic nucleotide substitution in the stem region.     

Effects of vertically transferred 3,3',4,4',5-pentachlorobiphenyl on gene expression in the ovaries of immature Sprague-Dawley rats

We have previously shown that 3,3',4,4',5-pentachlorobiphenyl (PCB-126) vertically transferred from dams potentially exerts a direct effect on the ovaries of offspring and adversely affects female puberty. To investigate its toxicological targets in ovarian tissues, mRNAs encoding representative peptides that regulate follicular development in granulosa cells, theca cells, and oocytes were quantified using ovaries collected on postnatal days (PND) 5, 15, and 24 from the offspring of dams administered oral doses of 0, 1 or 3 microg/kg PCB-126 starting 2 weeks prior to mating and continuing until 20 days after delivery. Quantification using the real-time RT-PCR method revealed that PCB-126 lowered the amounts of mRNAs that encoded the inhibin alpha- and inhibin/activin beta A-subunits from PND 15 onwards; the amounts of mRNAs for inhibin/activin beta B-subunit, follicle-stimulating hormone (FSH) receptor, and aromatase on PND 15; and the amounts of luteinizing hormone receptor mRNA on PND 24 compared with those of the age-matched controls. In contrast, no differences were noted for mRNAs encoding c-kit, growth differentiation factor-9, bone morphogenetic protein-15, or kit ligand for any of the age groups examined. The serum FSH level on PND 24 was higher than that in the control. Since the earliest effects on the mRNAs in the rat ovaries were observed in those expressed in the granulosa cells of the growing follicles after the antral follicles had developed, molecules in granulosa cells but not in oocytes during the early stages of the antral follicles might be the primary targets of vertically transferred PCB-126.     

Growth performance,survival and body composition of southern flounder Paralichthys lethostigma larvae fed different formulated microdiets

Three experiments were conducted to evaluate the effects of micro‐bound diets (MBD) on southern flounder larvae. In experiment 1, four MBDs were formulated with different protein sources as follows: MBD 1: herring meal, MBD 2: menhaden meal, MBD 3: menhaden and squid meal; MBD 4: menhaden, squid and herring meal. In experiment 2, four MBDs were formulated as follows: MBD 5: menhaden, squid and herring meal; MBD 6: menhaden, squid, herring and attractants; MBD 7: menhaden, squid, herring and casein, and MBD 8: menhaden, squid, herring, casein and attractants. In experiment 3, three groups were maintained as follows: Group 1: live feed; Group 2: co‐fed with MBD 6; and Group 3: MBD 6. In experiment 1 on 35 dph, survival and body weight (BW) of the fish fed MBD 4 was significantly higher than the MBDs 1 and 2. In experiment 2 on 34 dph, fish fed MBD 6 had significantly higher BW than the commercial microdiets. In experiment 3 on 21 dph, fish receiving only MBD had significantly lower survival than the other groups. Growth, survival and larval fatty acid composition suggested that co‐feeding MBD 6, a mixture of marine protein sources plus attractants was more effective than the other MBDs.