Steroid hormones do not reactivate Neospora caninum in ovariectomized mice     

Kobayashi A  Katagiri S  Kimura T  Ochiai K  Umemura T 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2002,64(9):773-777

The direct effects of three steroid hormones (progesterone, estradiol-17beta and corticosterone) on the growth of Neospora caninum (N. caninum) tachyzoite were examined in Vero cells. Subsequently, ovariectomized BALB/c mice infected with N. caninum were treated with physiological concentrations of the steroid hormones for 1 or 2 weeks. These hormones had no direct effect on the parasite growth in vitro. In the infected mice, there was no significant difference in the parasite distribution and histopathological changes between the hormone-injected and control groups. No mice showed parasitemia at the time of autopsy. These results suggest that physiological levels of steroid hormones (progesterone, estradiol-17beta and corticosterone) do not reactivate N. caninum in mice.  相似文献   

Establishment and characterization of a cell line from a chemically-induced mouse hepatoblastoma     

Kobayashi K  Sakairi T  Goto K  Tsuchiya T  Sugimoto J  Mutai M 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2000,62(3):263-267

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Effects of in vivo administration of anti-IL-10 or anti-IFN-gamma monoclonal antibody on the host defense mechanism against Plasmodium yoelii yoelii infection     

Kobayashi F  Ishida H  Matsui T  Tsuji M 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2000,62(6):583-587

Our previous reports indicated that C57BL/6 mice infected with a lethal variant of Plasmodium yoelii 17X (P. yoelii 17XL) produced high levels of interleukin 10 (IL-10) and interferon-gamma (IFN-gamma) while mice infected with the nonlethal variant of the parasite did not produce detectable levels of IL-10. In the present study, the involvement of IL-10 and IFN-gamma in exacerbation or regulation of blood-stage malaria was investigated by using the lethal variant of P. yoelii 17XL and monoclonal antibodies (mAb) against the cytokines. C57BL/6 mice were injected intraperitoneally with a neutralizing anti-IL-10 mAb or anti-IFN-gamma mAb after inoculation with P. yoelii 17XL. Treatment of mice with anti-IL-10 mAb resulted in substantial prolongation of survival and 60% of treated mice survived while 100% of control mice died by day 11. On the contrary, treatment of mice with anti-IFN-gamma mAb exacerbated infection and all mice died after an earlier period than those treated with normal rat Ig. No differences in parasitemias were found between treated and untreated mice. To elucidate the involvement of nitric oxide in the host protection or exacerbation, mice were treated with aminoguanidine, an inhibitor of nitric oxide synthetase, after inoculation of P. yoelii 17XL. Neither mortality nor parasitemia was influenced by the treatment. These results indicate that an IFN-gamma response is associated with protective immunity in mice infected with P. yoelii 17XL, while an IL-10 response is associated with disease exacerbation during the infection.  相似文献   

Seedborne fungi detected on stored solanaceous berry seeds and their biological activities     

Junji Nishikawa  Takao Kobayashi  Kazuto Shirata  Takashi Chibana  Keiko T. Natsuaki 《Journal of General Plant Pathology》2006,72(5):305-313

We isolated 629 fungi from 1296 berry seeds of solanaceous plants, including tomato (Lycopersicon esculentum), eggplant (Solanum melongena), bell pepper (Capsicum annuum), and red pepper (Capsicum annuum var. annuum) preserved for long and short terms. The isolates were classified into 22 genera excluding unidentified fungi, and the fungal floras were divided into two types: the tomato–eggplant and pepper groups. The results of cluster analysis with unweighted pair-group method with arithmetic average also supported these groups. Most tomato seeds infested with Geotrichum candidum germinated and grew the same as uninfested seeds. Cladosporium sphaerospermum and Arthrinium sp. isolated from eggplant seeds strongly suppressed germination, and Penicillium variabile suppressed seminal root elongation on eggplant. Alternaria alternata, Botrytis cinerea, and Myrothecium verrucaria detected from red pepper or bell pepper seeds were pathogenic to the fruits and the seedlings after artificial inoculation.  相似文献   

Transformation of trifoliate orange with rice chitinase gene and the use of the transformed plant as a rootstock     

Nobuhito Mitani  Shozo Kobayashi  Yoko Nishizawa  Takeshi Kuniga  Ryoji Matsumoto 《Scientia Horticulturae》2006

RCC2, cDNA clone encoding rice class-I chitinase, was introduced into trifoliate orange (Poncirus trifoliata Raf.). Chitinase activity of the transformed plants was higher than that of the non-transformed plants. The introduced gene was not detected in the scions grafted onto the transformed plants. The effect of the introduction of foreign gene into rootstocks on the scions was discussed.  相似文献   

猪隐秘杆菌型出血性坏死性脾炎     

Takemi OHBA  Masanori Kubo  Ariko Takaahima  Shigenori Imai  Koichi Kadota  任彬  常飞 《国外畜牧学(猪与禽)》2007,27(4):48-51

六月龄去势公猪表现昏睡、食欲不振、站立困难。尸检发现脾脏边缘呈多重出血灶。从脾脏、肾脏、肌肉和肝脏中分离出革兰氏阳性杆菌,对分离株(TO16177)的16S rDNA基因序列比较分析发现,其可能与未发表过的隐秘杆菌属HJ57-14E菌株(登记号:gi18873551)(比较675bp个碱基,相似性达99.7%)为同一个属。脾脏组织切片的组织学检查发现呈广泛性坏死和炎症,其中革兰氏阳性杆菌显而易见。肝脏中可见多病灶的坏死斑。免疫组织化学检测发现,分离株与抗化脓性隐秘杆菌属(Arcanobacterium pyogenes)和内氏放线菌(Actinomyces naeslundii)的多克隆抗体具有交叉反应,且与后者的交叉反应更强烈。相似的反应也见于扁桃体的化脓灶中分离株,偶尔也见于脾脏和淋巴结中的分离株。本研究结果表明,这种未公开发布的隐秘杆菌属的细菌会引起生长肥育猪多器官功能衰竭,而后继发急性出血性坏死性脾炎。  相似文献   

Aloe ring spot,a new disease of aloe caused by <Emphasis Type="Italic">Haematonectria haematococca</Emphasis> (Berk. &; Broome) Samuels &; Nirenberg (anamorph: <Emphasis Type="Italic">Fusarium</Emphasis> sp.)     

Yuuri Hirooka  Takao Kobayashi  Jun Takeuchi  Tsuyoshi Ono  Yasunori Ono  Keiko T. Natsuaki 《Journal of General Plant Pathology》2007,73(5):330-335

A ring spot disease of Aloe vera was found on leaves of potted seedlings of Aloe vera in Hachijojima and Chichijima Islands, Tokyo. From tissue of ring spot lesions, a fungus producing Fusarium-type conidia was consistently isolated. After 1 month, reddish perithecia of nectriaceous fungus had formed on the colonies of this isolate on PDA. These nectriaceous and Fusarium fungi were identified as Haematonectria haematococca and Fusarium sp., respectively. From a single ascospore isolation, the former was confirmed to be the teleomorph of the Fusarium sp. Typical ring spot lesions were reproduced by artificial inoculations using single ascospore and single conidium isolates. Inoculations of five species of genus Aloe revealed that they were highly susceptible except for A. arborescens. This is the first report of a disease on Aloe caused by H. haematococca (anamorph: Fusarium sp.) in Japan, and it was named aloe ring spot.  相似文献   

Calcium ion promotes successful penetration of powdery mildew fungi into barley cells     

Issei Kobayashi  Masako Yamada  Yuhko Kobayashi 《Journal of General Plant Pathology》2007,73(6):399-404

To determine whether Ca²⁺ promotes powdery mildew penetration, Ca²⁺-treated barley coleoptiles were inoculated with conidia of pathogenic and nonpathogenic fungi. Penetration efficiency of the pathogenic powdery mildew Blumeria graminis was enhanced by Ca²⁺ treatment, but that of the necrotrophic pathogen Helminthosporium sp. remained unaffected. Similarly, when actin-dependent penetration resistance is suppressed with cytochalasin A, Ca²⁺ treatment specifically enhanced penetration of the nonpathogenic powdery mildew Erysiphe pisi but not that of other nonpathogens. Calmodulin inhibitors suppressed the promotive effect of Ca²⁺ on B. graminis penetration. These results suggest that barley powdery mildew specifically requires Ca²⁺ and calmodulin for penetration.  相似文献   

Production and characterisation of monoclonal antibodies to cell wall components of the flax rust fungus     

Leanne J. Murdoch  Issei Kobayashi  Adrienne R. Hardham 《European journal of plant pathology / European Foundation for Plant Pathology》1998,104(4):331-346

Monoclonal antibodies have been raised against an haustorium-enriched sample prepared from flax leaves infected with the biotrophic flax rust pathogen Melampsora lini. The monoclonal antibodies were produced following conventional and co-immunisation procedures and the range of antibody specificities was compared. The preparation used as immunogen for the conventional protocol was a crude isolate of haustoria consisting of approx. 65% fungal haustoria, the other components being mainly mesophyll cells or cell wall and chloroplast fragments. Following hybridoma production, 40% of positive cell lines produced antibodies that reacted with haustoria and other fungal cells, but 60% bound to plant cells in the infected leaves. For the co-immunisation protocol, the preparation used for immunisation consisted of the crude isolate of haustoria mixed with serum raised against an haustorium-depleted leaf homogenate. In two fusions, 92-94% of the antibodies reacted with fungal cells, including 3 cell lines that localised specifically to the cell wall of haustoria. Only 6-8% of the antibodies produced via co-immunisation reacted with plant cells. The antigens targeted by the three haustorium-specific monoclonal antibodies are incorporated into the wall at early stages of haustorium development, remain in the wall throughout haustorium maturation, and are present in both compatible and incompatible interactions. The epitopes recognised by the monoclonal antibodies are oligosaccharide in nature and the antigens are highly resistant to extraction from the wall. These results highlight the value of the co-immunisation protocol for the production of monoclonal antibodies to specific components in an impure preparation and provide direct evidence for molecular differentiation within the wall of the haustorium of M. lini.  相似文献   

Transnationalism through the life course: Hong Kong immigrants in Canada     

Audrey Kobayashi  Valerie Preston 《Asia Pacific viewpoint》2007,48(2):151-167

Abstract: Transnationalism needs to be understood as a set of practices fashioned through the life course as well as in relation to contextual factors that include state policy and experiences of discrimination that affect entry to the labour force. The paradox of transnationalism is that families make strategic decisions to separate in order to maintain family unity and to advance the welfare of children. Emigrants from Hong Kong to Canada in the latter decades of the twentieth century were motivated by concern for family welfare and the quality of education in Canada. Yet economic livelihood prospects remained greater in Hong Kong than in Canada, prompting many families to become transnational ‘astronaut’ families with one or more members working in Hong Kong. Migration decisions tend to occur around key points of life‐course transition involving entry to and graduation from education, and entry to and exit from the labour force. Transnational practices are complex and multigenerational, involving different patterns for young adults, those in their middle years and the elderly.  相似文献