Characterisation of cross-reactivity of virus neutralising antibodies induced by feline panleukopenia virus and canine parvoviruses

It was recently reported that canine parvoviruses (CPV) had entered cat populations and induced disease in infected cats, while they had affected only dogs in the past. It is important to determine whether conventional feline panleukopenia virus (FPLV) vaccines protect against recent CPV infections. In this study, the cross-reactivity of virus-neutralising (VN) and haemagglutinin-inhibition (HI) antibodies in cats induced by FPLV and CPV s were examined. Lower cross-reactivities of VN and HI antibodies against each CPV strain were observed in cats experimentally inoculated with FPLV or vaccinated with an inactivated FPLV vaccine. In addition, we revealed the existence of a novel type of FPLV, which reacted weakly with antibodies induced by the conventional FPLV vaccine.     

Microscopic detection of reactive oxygen species generation in the compatible and incompatible interactions of Alternaria alternata Japanese pear pathotype and host plants

 Reactive oxygen species (ROS) generation was examined in the interaction of Alternaria alternata Japanese pear pathotype and host plants using three methods: nitro blue tetrazolium (NBT) method for microscopic detection of O₂ ⁻, diaminobenzidine (DAB) methods for microscopic detection of H₂O₂, and cerium chloride methods for ultrastructural detection of H₂O₂. ROS generation was detected by NBT and DAB methods at appressoria on leaves of susceptible cultivars and heat-shocked leaves of resistant cultivars but not in leaves of resistant cultivars. Ultrastructural detection by the cerium chloride method identified ROS generation at cell walls of appressoria and penetration pegs in susceptible, resistant leaves and heat-shocked leaves. These differences in the ultrastructural and microscopic data in resistant areas were due to the restriction of ROS generation in limited areas, the side facing the plant surface, of appressoria and penetration pegs. Therefore, ROS generation was apparently induced regardless of the resistance or susceptibility of the cultivar with the difference being in the volumes generated. After evaluating the pathological role of ROS generation in fungal structures, such generation was found to be associated with early penetration of cell walls in pear plants. Additionally, ROS generation in plants was also found in degrading pectin layers near infected hyphae and in plasma membrane modification sites in susceptible leaves but not in resistant leaves. ROS generation in susceptible leaves might be accompanied with plasma membrane damage, although the role of ROS generation in the pectin layers is not clear. ROS generation in both fungal and plant cells during their interaction was likely associated with the expression of susceptibility. Received: June 3, 2002 / Accepted: July 31, 2002     

Molecular cloning of a cDNA encoding the feline CD62L

We cloned a cDNA fragment encoding a feline homologue of L-selectin (CD62L). The extracellular region of the feline CD62L fragment contained a calcium-dependent (C-type) lectin domain, an epidermal growth factor-like domain, and two Sushi/CCP/SCR domains. The flow cytometric analysis confirmed that the feline CD62L molecule, which was expressed 293T cells, retained an epitope recognized by an anti-human CD62L monoclonal antibody (Leu-8).     

Seasonal changes in semen characteristics, composition of seminal plasma and frequency of acrosome reaction induced by calcium and calcium ionophore A23187 in Large White boars

This study attempted to explain the mechanisms regulating boar fertility by examining seasonal changes in semen characteristics, the composition of seminal plasma and responsiveness of sperm acrosomes to Ca(2+) and the Ca(2+) ionophore A23187 (Ca(2+)/A23187). Sperm-rich and sperm-poor fractions were separately collected from 3 mature fertile Large White boars once a month over a one-year period. During the period of study, ambient temperature and relative humidity were recorded for within the stall in which the boars were kept and the semen characteristics, composition of the seminal plasma of sperm-rich fractions, and occurrence of the acrosome reaction in response to Ca(2+) (3 mM)/A23187 (0.3 microM) were examined. The highest mean maximum and minimum ambient temperatures were recorded in August-September, whereas the lowest mean maximum and minimum ambient temperatures were recorded in December and January, respectively. There was a moderate peak in relative humidity from July to October. The lowest percentages of motile spermatozoa and of spermatozoa with intact acrosomes and highest percentage of spermatozoa with abnormal morphology and strongest agglutination were seen in August-September. The total protein and albumin concentrations were lowest in August-September. Testosterone levels increased gradually as day length decreased after the summer solstice (June) and peaked in October-November. The percentage of acrosome reactions in response to Ca(2+)/A23187 was highest with the quickest response in August-September, as shown by the shortest time required for 50% of relative acrosome reactions. The farrowing rates were lowest in these same 2 months. These results suggest that seasonal infertility in Large White boars may be due, at least in part, to a combination of low motility, abnormal morphology including acrosomal abnormality, and early occurrence of the acrosome reaction in response to stimulus, possibly resulting from a decrease in acrosomal stabilizing proteins in the seminal plasma during summer. These changes may be modulated by heat/humidity stress and/or photoperiod-regulated testosterone.     

Time-dependent changes in protein phosphorylation patterns in rat brain synaptosomes caused by deltamethrin

Effects of deltamethrin, a powerful pyrethroid insecticide, on the protein phosphorylation and dephosphorylation processes during depolarization in rat brain synaptosomes were studied by using [³²P]phosphoric acid as a starting radiotracer and high external concentration of potassium ions or veratridine (10^?-5 M) as depolarizing agents. At the onset of depolarization there was a quick rise in phosphorylation in various synaptic proteins for about 15–30 s followed by a gradual decline in levels of phosphorylation. The effect of deltamethrin (10^?-7 M) on this system was found to be dependent on the length of preincubation of the synaptosome with the pesticide prior to depolarization. At an early stage (0–3 min preincubation period) it caused a modest suppression of protein phosphorylation activities. When the period of deltamethrin preincubation was extended to 5–20 min, however, it caused a significant increase in protein phosphorylation throughout the depolarization period. At the later stage of the action of deltamethrin (e.g. preincubation period of 30–40 min), deltamethrin-treated synaptosomes no longer responded to the depolarization signal to raise the level of phosphorylation on many proteins. These results indicate that deltamethrin's actions on the synaptic process are complex. Depending on the length of exposure, its effects on protein phosphorylation responses in intact synaptosomes could be either stimulatory or inhibitory. To study the cause of deltamethrin-induced synaptic block at the later stage, effects of deltamethrin on protein kinases were studied by using lysed synaptic membranes with [gamma-³²P]ATP. Deltamethrin was shown to inhibit calcium–calmodulin-dependent protein phosphorylation activities at 10^?-7 M when given directly to the enzyme source 10 min prior to the addition of [³²P]ATP. Such an observation helps to explain the inhibitory action of deltamethrin on protein phosphorylation which occurs at the late stage of its action (i.e. preincubation time > 20 min).     

T-cell lymphoma in a savanna monkey (Cercopithecus aethiops) probably related to simian T-cell leukemia virus infection

Lymphoma was seen in an 11-year-old female savanna monkey (Ceropithecus aethiops). The superficial inguinal and visceral lymph nodes were markedly enlarged, and their architecture was completely effaced by neoplastic cells. The neoplastic cells, which were highly pleomorphic, resembled those in adult T-cell lymphoma-leukemia in humans. Ultrastructurally the neoplastic cells were characterized by nuclear irregularity and clustered dense bodies, and almost all cells showed positivity for CD3. The animal had been reared with her family, and her mother and 2 brothers had antibodies reactive to human T-cell leukemia virus. This virus serologically cross-reacts with simian T-cell leukemia virus, which may be the causative agent of the present neoplasm.