Bird responses to broad-leaved forest patch area in a plantation landscape across seasons   总被引：1，自引：0，他引：1  

Yuichi Yamaura  Susumu Ikeno  Makoto Sano  Kimiko Okabe  Kenichi Ozaki   《Biological conservation》2009,142(10):2155-2165

Although plantation forests have widely replaced native forests worldwide, few studies have examined the effects of plantation forestry on organisms at the landscape level. In this study, we examined the effects of broad-leaved forest patch area (1.4–312 ha) on bird assemblages in a conifer plantation-dominated landscape during wintering and breeding seasons. We also surveyed birds in the plantation matrix and treated the patch area of the matrix as 0. We examined whether the detection rates of species changed suddenly across patch area (threshold) using segmented regression. We found that species richness increased with patch area in both seasons. Responses of detection rates to patch area varied and were categorized as follows: insensitive, linear increase and decrease, quadratic increase and decrease, concave and convex. Thresholds indicating that the detection rate suddenly increased above a certain patch area were found for two species only in the winter. Species responses varied more in the winter than in the breeding season. Certain ecological traits of species were consistently associated with the responses to patch area across seasons (migratory strategy, nesting substrate and foraging trait), while body weight was only associated in the winter. Because species richness and detection rates of many species were high in large patches, large broad-leaved forests (especially >40 ha) should be retained and restored with high priority. Additionally, bird responses to patch area in the winter should not be ignored because many species required large patches during the winter season.  相似文献   

In vitro suppression of proliferation of Marek's disease lymphoma cell line (MDCC-MSB1) by peritoneal exudate cells from chickens infected with MDV or HVT     

K Ozaki  H Kodama  M Onuma  H Izawa  T Mikami 《Zentralblatt für Veterin?rmedizin. Reihe B. Journal of veterinary medicine. Series B》1983,30(3):223-231

  相似文献   

Abscess-forming inflammatory granulation tissue with Gram-positive cocci and prominent eosinophil infiltration in cats: possible infection of methicillin-resistant Staphylococcus     

Ozaki K  Yamagami T  Nomura K  Haritani M  Tsutsumi Y  Narama I 《Veterinary pathology》2003,40(3):283-287

We occasionally encounter feline cervical or mesenteric lesions diagnosed histopathologically as abscess or inflammatory granulation tissue with eosinophil infiltration. Gram-positive cocci accompany the lesions. In the present study, such lesions obtained from 27 cats were examined to evaluate the histopathologic features and the nature of the causative bacteria. The average age was 7.3 +/- 3.5 years. No sex predilection was observed. Most frequent locations of the lesions included the abdominal cavity with/without mesenteric lymph nodes (11/27, 41%) and subcutaneous tissue or lymph nodes of the neck (9/27, 33%). Common clinical presentation was a localized mass. Grossly, the lesions contained abscesses in the center and were surrounded by fibrous tissue. Microscopically, the necrotic zone contained bacterial colonies. Large numbers of eosinophils and macrophages infiltrated the area surrounding the necrotic tissue. The surrounding connective fiber-rich granulation tissue demarcated the eosinophilic abscess. The bacteria were Gram-positive cocci in 23 of the 27 cats and were positive for anti-staphylococcus antiserum in 19 of the 23 cats. In 15 out of 17 lesions, the colonies expressed immunoreactivity to penicillin-binding protein 2', which is a drug-resistance gene product of methicillin-resistant Staphylococcus (MRS) species. These findings suggest strongly that MRS causes this type of infectious lesion.  相似文献   

Neurotropism of the 1997 Hong Kong H5N1 influenza virus in mice   总被引：12，自引：0，他引：12  

Tanaka H  Park CH  Ninomiya A  Ozaki H  Takada A  Umemura T  Kida H 《Veterinary microbiology》2003,95(1-2):1-13

The direct transmission of H5N1 influenza A viruses from chickens to humans in Hong Kong in 1997 emphasized the need to have information on the pathogenesis of avian influenza virus infection in mammals. H5N1 influenza viruses isolated from patients during the incident killed experimentally infected mice. The principal lesions of the mice were broncho-interstitial pneumonia and nonsuppurative encephalitis. Infectious viruses and/or viral antigens were detected in the brain as well as in the trigeminal and vagal ganglia but not in the blood of the mice. These findings suggest that the virus reached the brain through the vagus and/or trigeminal nerves following replication in the respiratory mucosa. The results imply that neurotropism of the H5N1 virus in mice is a novel characteristic in the pathogenesis of infection by human influenza virus isolates.  相似文献   

Detection of Babesia equi (Laveran, 1901) by nested polymerase chain reaction     

Nicolaiewsky TB  Richter MF  Lunge VR  Cunha CW  Delagostin O  Ikuta N  Fonseca AS  da Silva SS  Ozaki LS 《Veterinary parasitology》2001,101(1):9-21

We describe a nested polymerase chain reaction (PCR) for the detection of Babesia equi in equine infected erythrocytes using oligonucleotides designed on the published sequence of a B. equi merozoite antigen gene (ema-1). A 102bp DNA fragment is specifically amplified from B. equi but not from Babesia caballi, Babesia bovis or Babesia bigemina DNA. In a mock infection we were able to detect down to six infected cells in 10(8) equine erythrocytes or to detect the parasite in blood with an equivalent parasitemia of 0.000006%. Furthermore, gene polymorphism was found by performing a PCR-RFLP (PCR combined with restriction fragment length polymorphism) on both the 102bp and the entire ema-1 gene DNA amplified from two B. equi isolates, Florida (USA) and Pelotas (Southern Brazil) isolates. The polymorphism was confirmed by sequencing the entire ema-1 gene from the B. equi isolate Pelotas. Our results demonstrate that the ema-1 based nested PCR is a valuable technique for routine detection of B. equi in chronically infected horses. It may be used for epidemiological and phylogenetic studies of the parasite as well as monitoring B. equi infected horses in chemotherapeutic trials.  相似文献   

Production of experimental arteriosclerosis in spontaneously hypertensive rats, SHR/NCrj     

N Isegawa  K Doi  T Mizutani  A Ozaki  T Owada  T Mitsuoka 《Nippon juigaku zasshi. The Japanese journal of veterinary science》1984,46(4):443-451

  相似文献   

Canine Distemper Virus Induces Apoptosis Through Caspase‐3 and ‐8 Activation in Vero Cells     

M. Kajita  H. Katayama  T. Murata  C. Kai  M. Hori  H. Ozaki 《Zoonoses and public health》2006,53(6):273-277

  相似文献   

Rapid communication: two highly polymorphic dinucleotide microsatellites in rainbow trout (Oncorhynchus mykiss): OmyRGT18TUF and OmyRGT23TUF     

Khoo SK  Ozaki A  Sakamoto T  Okamoto N 《Journal of animal science》2000,78(2):490-491

  相似文献   

Behavior and mutation of <Emphasis Type="Italic">Ralstonia solanacearum</Emphasis> in <Emphasis Type="Italic">Solanum toxicarium</Emphasis> grown in aseptic culture     

Taro Mori  Katsumi Ozaki  Hiromi Matsusaki  Naotaka Matsuzoe 《Journal of General Plant Pathology》2007,73(2):142-146

To study the behavior and mutation of Ralstonia solanacearum in Solanum toxicarium, which is resistant to bacterial wilt, S. toxicarium was grown in aseptic culture and inoculated with R. solanacearum. Although 60%–80% of the inoculated plants were wilting after 2 to 3 days, most wilted plants had recovered by 20 days after inoculation. The pathogen was reisolated from over 98% of inoculated plant stems, but the percentage of recovery decreased the closer the isolation sites were toward the upper stem sections. Three colony types, characterized as fluidal white, nonfluidal red, and a mixture of fluidal white and nonfluidal red, were reisolated from the stems. Nonfluidal red colonies were less virulent on tomato plants than fluidal white colonies.  相似文献   

Phagocytotic activation of muscularis resident macrophages inhibits smooth muscle contraction in rat ileum     

Sato K  Torihashi S  Hori M  Nasu T  Ozaki H 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2007,69(10):1053-1060

Intestinal muscularis resident macrophages distributed in myenteric region may play an important role in the immunological host defense against infection. In this study, we investigated the phagocytic stimulation of resident macrophages on cyclooxygenase-2 (COX-2) expression and smooth muscle contraction in the small intestine of rat. After the injection of FITC-dextran to rat, phagocytosed macrophages could be detected in the myenteric plexus. FITC-positive macrophages were also immunostained with COX-2 antibody. The number of COX-2 immunopositive cells increased in a time-dependent manner reaching its maximum at 4 hr after the injection, which then decreased gradually but considerable number of cells were still remained on 7 days. The injection of FITC-dextran, however, did not change the population of ED2-positive resident macrophages even on 7 days. Production of PGE2 was significantly higher in the dextran treated tissue as compared to control tissue. In the smooth muscle tissue phagocytosed dextran, carbachol-induced contraction was significantly decreased. The suppression of the carbachol-induced contraction was completely restored by COX inhibitor, indomethacin. Finally we demonstrated that, in freshly isolated macrophage cells, addition of dextran induced a slow and sustained increase in intracellular Ca2+ concentration. These results indicate that phagocytotic activation of muscularis resident macrophages induces COX-2 gene expression and then results in production of PGE2 to suppress the smooth muscle contractile activity.  相似文献