Comparison of macrophage scavenger receptor-A knockout mice with wild type ones in the immune response against repeated infestation with Haemaphysalis longicornis

Using macrophage scavenger receptor-A knockout (SRKO) mice, we examined the role of macrophage class A scavenger receptors (MRS-A) on the immune response and acquisition of host resistance against repeated infestation with Haemaphysalis longicornis. Except for one batch of nymphs that infested one of the SRKO (SR-/-) mice and showed no appreciable reduction in body weight, all the other groups of nymphs manifested significant decrease in body weight. Both SR-/- and wild type (SR+/+) mice showed a sustained increase in anti-tick antibody titers, but SR+/+ mice showed significantly higher titers. The IFN-gamma assayed in SR-/- mouse immune sera was substantially less compared with that in SR+/+ mice. Immune sera from SR-/- and SR+/+ mice recognized the 51 and 44 kDa, and 44 kDa proteins, respectively, of the salivary gland antigen. The difference in the level of anti-tick resistance manifested by both groups of mice may be influenced by less efficient trapping and processing of tick antigens by macrophages in mice lacking for the macrophage scavenger receptors, and consequently affected the cascade of Th1 and Th2 responses. We have thus obtained valuable data that strongly infer the role of MSR-A in enhancing host defense against repeated infestation with H. longicornis.     

Isolation and antimicrobial susceptibility of Plesiomonas shigelloides from great cormorants (Phalacrocorax carbo hanedae) in Gifu and Shiga Prefectures,Japan

Plesiomonas shigelloides is a causal agent of gastroenteritis, sepsis and meningitis in humans. We examined the prevalence of P. shigelloides among great cormorants (Phalacrocorax carbo hanedae) in Japan and the antimicrobial susceptibility of isolates. P. shigelloides was isolated from 33 (47.8%) of 69 fecal samples from great cormorants in 2014. All 33 isolates were subjected to antimicrobial susceptibility testing using broth microdilution methods, which showed resistance to ampicillin (31 isolates, 93.9%), tetracycline (two isolates, 6.1%) and trimethoprim (one isolate, 3.0%). The high prevalence of P. shigelloides in the great cormorants implicates the possible microbiological risk to public health.     

Comparison of rDNA-ITS Sequences between Potato and Tobacco Strains in <Emphasis Type="Italic">Rhizoctonia solani</Emphasis> AG-3

Genetic diversity among 51 isolates of Rhizoctonia solani AG-3, representing potato and tobacco populations, was inferred from the sequences of the internal transcribed spacer (ITS) and 5.8S ribosomal RNA (rRNA) gene. The 5.8S rDNA sequence was completely conserved not only in AG-3, but across all the AG isolates examined, whereas the rDNA-ITS sequence was found to be variable among the isolates. The nucleotide sequence similarity in the ITS 1 region was high (96-100%) for isolates within each of the two populations, but was 91-92% for isolates from different populations. The AG-3 isolates had 56 to 91% sequence similarities in the ITS 1 region with R. solani isolates of the other AGs. Phylogenetic analysis based on the ITS-5.8S rDNA sequence data indicated that the different populations in AG-3 are distantly related to each other. Genetic divergence between the two populations was also supported by the results of DNA-DNA hybridization studies. This study suggests that AG-3 consists of two genetically isolated groups corresponding to separate subgroups: AG-3 PT (potato type) and AG-3 TB (tobacco type). Specific primer sets for the detection of the two AG-3 subgroups were developed from the aligned rDNA-ITS sequences. Received 22 April 1999/ Accepted in revised form 2 July 1999     

Seroepidemiologic studies on Babesia caballi and Babesia equi infections in Japan

Antibodies to Babesia caballi and Babesia equi were examined on a total of 2,019 horse serum samples that had been collected in 1971-1973 by the National Institute of Animal Health by enzyme-linked immunosorbent assay (ELISA) using recombinant proteins and by Western-blot analysis. Based on the criterion for positivity by ELISA, 5.4% (109/2,019) and 2.2% (44/2,019) had antibodies against B. caballi and B. equi, respectively. The ELISA-positive sera were further examined by Western blot; 30/109 for B. caballi and 2/ 44 for B. equi were positive for native B. caballi or B. equi, but none of them was seropositive for both infections. Based on the results of this study, further investigations should be required to survey horses that have arrived in Japan relatively recently and tick vectors of equine Babesia using ELISA with some recombinant protein, a parasite detection method in an in vitro culture of equine Babesia, and PCR testing.     

Temperature and metal ions-dependent activity of the family I inorganic pyrophosphatase from the swine roundworm Ascaris suum

Temperature dependence, heat stability and metal ions-dependent activity were examined on the Family I inorganic pyrophosphatase (PPase) recently identified from Ascaris suum. Recombinant A. suum PPase (rAsPPase) showed an optimal activity at 55 degrees C. The rAsPPase was heat stable at 40 degrees C in the absence of added Mg(2+) and at 50 degrees C in its presence. The enzyme required divalent metal ions for its activity. The preferences for the metal ions (5 mM concentration) were in the order: Mg(2+)> Co(2+)> Cu(2+)> Fe(2+)> Zn(2+)> Mn(2+). On the contrary, enzyme activity was inhibited by Ca(2+). These findings suggest that catalytic features of AsPPase are consistent with the Family I PPases reported from a wide range of organisms.     

Clinico-pathological findings in peripartum dairy cows fed anion salts lowering the dietary cation-anion difference: involvement of serum inorganic phosphorus, chloride and plasma estrogen concentrations in milk fever

In our previous study, it was demonstrated that the administration of anion salts, which slightly lower the dietary cation-anion difference (DCAD), in the prepartum period is safe and effective for preventing milk fever in multiparous cows. In the present study, several clinico-pathological constituents in serum and urine, which might be related to milk fever, were analyzed using stored samples from the previous study to identify clinico-pathological parameters for easily evaluating the efficacy of lowering DCAD and to further investigate the mechanism by which lowering DCAD prevents milk fever. Among the parameters analyzed in the present study, inorganic phosphorus (iP) was involved in milk fever because the serum concentration and urinary excretion of iP were significantly higher in the group of primiparous cows (heifer group), which did not develop hypocalcemia, than those in other groups of multiparous cows. Serum chloride concentrations in the heifer group and the group of multiparous cows fed anion salts (anion group) tended to remain higher than those in other control groups of multiparous cows suggesting that serum chloride concentration may be utilized for evaluating the status of metabolic acidosis and the efficacy of lowerng DCAD in dairy cows fed anion salts. In addition, plasma estradiol-17beta concentration in the heifer group tended to be lower at parturition compared with that in other multiparous groups suggesting that estrogen known as a potent inhibitor of bone resorption may be involved in developing milk fever.     

Preventive effect of mildly altering dietary cation-anion difference on milk fever in dairy cows

In the present study, we examined whether mildly altering dietary cation-anion difference (DCAD) contributes to the prevention of milk fever in dairy cows. Thirty multiparous cows and ten primiparous cows (heifer group) were used in this study and the multiparous cows were randomly divided into three groups of ten animals each (anion, non-anion and control groups). The cows in the anion group were given supplemental salts that slightly lowered DCAD. These salts consisted of 115 g of CaCO3, 42 g of CaHPO4, 65 g of MgSO4 x 7 H2O and 80 g of CaCl2 x 2 H2O as a daily dose for each cow, using a catheter from 21 days before the expected date of parturition until parturition. The cows in the non-anion group were given only the same Ca, Mg and ip supplement but no sulfate and chloride salts as that in the anion group. The cows in the control and heifer groups were not given any additional supplement. The incidence of hypocalcemia in the anion group decreased to approximately half of those in the non-anion and control groups, while the heifer group did not develop hypocalcemia at all. In addition, the number of days spent for the treatment of hypocalcemia and the number of drug bottles (calcium borogluconate solution) used for the treatment decreased to less than half in the anion group compared with those in the non-anion and control groups. At parturition, the serum Ca concentration in the control (6.2 +/- 1.9 mg/dl, mean +/- standard deviation) and non-anion groups (6.4 +/- 1.7 mg/dl) were significantly lower than that in the heifer group (8.3 +/- 0.4 mg/dl), and the level in the anion group was intermediate (7.3 +/- 1.3 mg/dl). The change in ionized Ca concentration was almost the same as that in serum Ca concentration, but only the concentration in the anion group tended to increase slightly from a week before parturition and was significantly higher than that in all other groups three days before parturition. Urinary pH in the anion group was maintained at a mildly acidic level (6.8-7.0) for the last two weeks before parturition, compared with those in the control (7.3-7.5) and non-anion groups (7.9-8.1), and similar to that in the heifer group (6.3-7.3). The urinary Ca excretion was the highest in the anion group among all groups during the prepartum period. There were no specific changes in the excretion of parathyroid hormone and 1,25-dihydroxyvitamin D in all groups of multiparous cows while the levels of these hormones remained low in the heifer group throughout the experimental period. The data in the present study indicates that the administration of anion salts that slightly lowered DCAD in the preparum period was effective for preventing milk fever in multiparous cows. Safe and mild metabolic acidosis induced by the anion salts could be evaluated by urinary pH (6.8-7.0), and might increase the responsiveness to Ca requirement at parturition through some complex mechanisms unrelated to the excretion of Ca-related hormones. In addition, it was clarified that primiparous cows have a high potential to respond to sudden Ca demand unrelated to hormone excretion, and their Ca metabolism was in some respects similar to that in multiparous cows fed anion salts. Therefore, manipulating mildly DCAD is expected to be an effective, safe and natural method for preventing milk fever in dairy cows.     

Mapping of rRNA gene loci in the mice, Mus musculus molossinus (Japan) and Mus musculus musculus (Russia) by double color FISH

Ribosomal RNA gene (rDNA) loci of Russian Mus musculus musculus and of Japanese Mus musuculus molossinus were mapped by double color FISH. The total number of rDNA loci was varied from 5 to 12, although the loci on chromosomes 12, 15, 16, 18, and 19 were common to all mice examined. Instead, polymorphisms of the rDNA loci were found on chromosomes 1, 5, 8, 9, 10, 11, 13 and 17. The novel rDNA loci of M. m. musculus were found in Nov/TUA strain on chromosomes 8 and 17. These observations, together with those of previous reports, suggest that the rDNA loci of Mus musculus species are in the evolutionary process of further translocation to other chromosomes.     

An investigation into the distribution, host-preference and population density of Ixodid ticks affecting domestic animals in Bangladesh

To study the distribution, host-preference and population density of ixodid ticks in Bangladesh, an attempt was made to collect adult ticks from various host animals in three distinct topographic zones, viz. flood plains, hills and steppe ‘Barind’. Five species of ixodid ticks were recorded, namely, Boophilus microplus (56.3%), Haemaphysalis bispinosa (11.3%), Rhipicephalus sanguineus (14.7%), Hyalomma anatolicum anatolicum (15.0%) and Amblyomma testudinarium (2.8%). The data showed that B. microplus occurred predominantly on cattle (42.4%). The other hosts involved were buffaloes (12.5%), goats (25.5%) and pigs (8.2%). H. bispinosa mostly parasitized goats (31.5%) rather than cattle (12.0%) and buffaloes (10.8%). R. sanguineus was principally a dog tick (27.4%) but also parasitized cattle (10.8%) and goats (6.8%). H. a. anatolicum was restricted to cattle (19.2%) and A. testudinarium was found on both cattle (4.4%) and pigs (2.3%). These results indicate that ixodid ticks are not strictly host-specific except for H. a. anatolicum. The population density of these ticks was significantly (p < 0.01) influenced by the changing of seasons. B. microplus, H. bispinosa and R. sanguineus were by far the most widely distributed species; the distribution of H. a. anatolicum was restricted to the steppe ‘Barind tract’ and A. testudinarium was found in the hilly regions only.