Scale-dependent effects of habitat area on species interaction networks: invasive species alter relationships     

S Sugiura  H Taki 《BMC ecology》2012,12(1):11

ABSTRACT: BACKGROUND: The positive relationship between habitat area and species number is considered a fundamental rule in ecology. This relationship predicts that the link number of species interactions increases with habitat area, and structure is related to habitat area. Biological invasions can affect species interactions and area relationships. However, how these relationships change at different spatial scales has remained unexplored. We analysed understory plant-pollinator networks in seven temperate forest sites at 20 spatial scales (radius 120-2020 m) to clarify scale-associated relationships between forest area and plant-pollinator networks. RESULTS: The pooled data described interactions between 18 plant (including an exotic) and 89 pollinator (including an exotic) species. The total number of species and the number of interaction links between plant and pollinator species were negatively correlated with forest area, with the highest correlation coefficient at radii of 1520 and 1620 m, respectively. These results are not concordant with the pattern predicted by species-area relationships. However, when associations with exotic species were excluded, the total number of species and the number of interaction links were positively correlated with forest area (the highest correlation coefficient at a radius of 820 m). The network structure, i.e., connectance and nestedness, was also related to forest area (the highest correlation coefficients at radii of 720-820 m), when associations with exotics were excluded. In the study area, the exotic plant species Alliaria petiolata, which has invaded relatively small forest patches surrounded by agricultural fields, may have supported more native pollinator species than initially expected. Therefore, this invasive plant may have altered the original relationships between forest area and plant-pollinator networks. CONCLUSIONS: Our results demonstrate scale-dependent effects of forest area on the size and structure of plant-pollinator networks. We also suggest that a single exotic plant species can impact plant-pollinator networks, even in temperate continental habitats.  相似文献   

Rapid and sensitive detection of “<Emphasis Type="Italic">Candidatus</Emphasis> Liberibacter asiaticus” by cycleave isothermal and chimeric primer-initiated amplification of nucleic acids     

Naoya Urasaki  Shinji Kawano  Hiroyuki Mukai  Takashi Uemori  Osamu Takeda  Teruo Sano 《Journal of General Plant Pathology》2008,74(2):151-155

We developed a detection method for “Candidatus Liberibacter asiaticus”, causal agent of citrus huanglongbing, using isothermal and chimeric primer-initiated amplification of nucleic acids combined with cycling probe technology (Cycleave ICAN). With Cycleave ICAN, the reaction was done in one tube in 1 h without the need for electrophoresis, and false positives were not generated. In addition, Cycleave ICAN method was more sensitive than the conventional PCR method. Cycleave ICAN helps shorten the time for the large-scale detection needed to manage huanglongbing.  相似文献   

Chilli pepper rugose mosaic disease caused by Pepper veinal mottle virus occurs on Ishigaki Island,Japan     

Kosuke Matsumoto  Ryosuke Yasaka  Tamotsu Setoyama  Shinji Kawano  Kazusato Ohshima 《Journal of General Plant Pathology》2016,82(1):57-60

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Soil temperature and moisture-based estimation of rates of soil aggregate formation by the endogeic earthworm Eisenia japonica (Michaelsen, 1892)     

Satoshi Kaneda  Shinji Ohkubo  Rota Wagai  Yasumi Yagasaki 《Biology and Fertility of Soils》2016,52(6):789-797

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Identification of genes required for the fitness of Rhodococcus equi during the infection of mice via signature-tagged transposon mutagenesis     

Nuttapone SANGKANJANAVANICH  Tsutomu KAKUDA  Yasunori SUZUKI  Yukako SASAKI  Shinji TAKAI 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2021,83(8):1182

Rhodococcus equi is a Gram-positive facultative intracellular bacterium that causes pyogranulomatous pneumonia in foals and immunocompromised people. In the present study, signature-tagged transposon mutagenesis was applied for the negative selection of R. equi mutants that cannot survive in vivo. Twenty-five distinguishable plasmid-transposon (plasposon) vectors by polymerase chain reaction (PCR), each containing a unique oligonucleotide tag, were constructed and used to select the transposon mutants that have in vivo fitness defects using a mouse systemic infection model. Of the 4,560 transposon mutants, 102 mutants were isolated via a real-time PCR-based screening as the mutants were unable to survive in the mouse model. Finally, 50 single transposon insertion sites were determined via the self-cloning strategy. The insertion of the transposon was seen on the virulence plasmid in 15 of the 50 mutants, whereas the remaining 35 mutants had the insertion of transposon on the chromosome. The chromosomal mutants contained transposon insertions in genes involved in cellular metabolism, DNA repair and recombination, gene regulation, non-ribosomal peptide synthesis, and unknown functions. Additionally, seven of the chromosomal mutants showed a reduced ability to multiply in the macrophages in vitro. In this study, we have identified several biosynthetic pathways as fitness factors associated with the growth within macrophages and survival in mice.  相似文献   

Improved survival and growth performances with stocking density manipulation and shelter availability in bagrid catfish Mystus nemurus (Cuvier & Valenciennes 1840) larvae     

Sharifah Rahmah  Keitaro Kato  Shinji Yamamoto  Kenji Takii  Osamu Murata  Shigeharu Senoo 《Aquaculture Research》2014,45(12):2000-2009

Manipulation of stocking densities (10, 20, 30, 40 and 50 larvae L^?1), each with or without the presence of shelter was conducted to determine the effects on survival, cannibalism and growth performances of larval bagrid catfish Mystus nemurus (Valenciennes 1840) from 2 to 14 days after hatching. This study revealed that stocking density significantly affected survival, cannibalism, total length, feed intake, specific growth rate and final weight of bagrid catfish larvae. Significantly higher survival was observed at moderate stocking density of more than 20 but less than 50 larvae L^?1. Survival was significantly low beyond this threshold and was the lowest at 10 larvae L^?1, coincides with the highest cannibalism. Total length, feed intake, specific growth rate and final weight were significantly higher at 10 larvae L^?1. Shelter significantly improved total length and feed intake. No significant effects of stocking density and shelter were observed on the apparent feed conversion ratio and coefficient of variation. There was also no significant interaction between stocking density and shelter in all parameters. This study suggests that bagrid catfish larvae could be cultured at more than 20 but less than 50 larvae L^?1 with the availability of shelter for optimal larviculture condition.  相似文献   

CONTRAST-ENHANCED ULTRASONOGRAPHY FOR CHARACTERIZATION OF CANINE FOCAL LIVER LESIONS     

KENSUKE NAKAMURA  SATOSHI TAKAGI  NOBORU SASAKI  WICKRAMASEKARA RAJAPAKSHAGE BANDULA KUMARA  MASAHIRO MURAKAMI  HIROSHI OHTA  MASAHIRO YAMASAKI  MITSUYOSHI TAKIGUCHI 《Veterinary radiology & ultrasound》2010,51(1):79-85

In six normal beagles and 27 dogs with spontaneous focal or multifocal liver lesions, contrast-enhanced ultrasonography using Sonazoid^® was performed. Sonazoid^® is a newly developed second-generation contrast agent with the ability to be used for real-time contrast imaging along with parenchymal imaging. An appropriate protocol for the evaluation of all three phases (arterial, portal, and parenchymal) was established based on the results for normal beagles. By evaluation of the echogenicity of hepatic nodules during the arterial and parenchymal phases it was possible to differentiate malignant tumors from benign nodules with very high accuracy. In 15 of 16 dogs diagnosed as malignant tumors, nodules were clearly hypoechoic to the surrounding normal liver during the parenchymal phase. Additionally, malignant tumors had different echogenicity compared with the surrounding normal liver during the arterial phase in 14 of 15 dogs. In the portal phase, there were no characteristic findings. Contrast-enhanced ultrasonography with Sonazoid^® appears to improve the characterization of canine focal and multifocal hepatic lesions.  相似文献   

Effects of anthocyanins on psychological stress-induced oxidative stress and neurotransmitter status     

Rahman MM  Ichiyanagi T  Komiyama T  Sato S  Konishi T 《Journal of agricultural and food chemistry》2008,56(16):7545-7550

There is strong evidence that oxidative stress participates in the etiology of neurodegenerative diseases such as Parkinson's, and Alzheimer's diseases. Moreover, emotional stress effects in the central nervous system play a vital role in homeostasis. The protective effect of anthocyanins on the cerebral oxidative stress was studied using the whiskers cut model. In mice, such treatment causes psychological or emotional distress leading to oxidative stress in tissues. To investigate the in vivo antioxidant activity of anthocyanins, an extract of Vaccinium myrtillis L., an anthocyanin mixture, was orally administered (100 mg/kg of body weight.) to mice for 7 days, and then psychological stress was assessed by cutting off their whiskers. Whisker removal increased both protein carbonyl formation and lipid peroxidation in the brain, heart, kidney, and liver. Further, the levels of oxidative markers showed regional differences in the brain. Concomitantly, dopamine neurotransmitter levels were altered in both the midbrain and the brain cortex. Orally administered anthocyanins were also active in the brain, suppressing stress-induced cerebral oxidative stress and dopamine abnormalities in distressed mice. These effects of anthocyanin treatment suggest their possible usefulness for the treatment of cerebral disorders related to oxidative stress.  相似文献   

Dietary phosphatidylinositol prevents the development of nonalcoholic fatty liver disease in Zucker (fa/fa) rats   总被引：1，自引：0，他引：1  

Shirouchi B  Nagao K  Inoue N  Furuya K  Koga S  Matsumoto H  Yanagita T 《Journal of agricultural and food chemistry》2008,56(7):2375-2379

Recent studies have shown that dietary phospholipids, especially phosphatidylcholine and phosphatidylserine, have various beneficial biological effects. However, there are not enough data concerning the physiological function of dietary phosphatidylinositol (PI). The metabolic syndrome, a cluster of metabolic abnormalities such as dyslipidemia, diabetes mellitus, and hypertension, is a widespread and increasingly prevalent disease in industrialized countries. Nonalcoholic fatty liver disease (NAFLD) is often associated with features of the metabolic syndrome. NAFLD describes the spectrum of liver damage ranging from hepatic steatosis to steatohepatitis, liver fibrosis, and cirrhosis, and it is emerging as the most common liver disease worldwide. The present study examined whether dietary PI protects Zucker ( fa/ fa) rats from the metabolic syndrome. For 4 weeks, rats were fed semisynthetic diets containing either 7% soybean oil or 5% soybean oil plus 2% PI. Dietary PI markedly prevented the development of hepatomegaly and hepatic steatosis and lowered hepatic injury markers in serum. Additionally, hyperinsulinemia was relieved by the feeding of dietary PI in Zucker rats. These effects were attributable to an increase in serum adiponectin, enhancement of fatty acid beta-oxidation, and suppression of mRNA expression of inflammatory genes in the liver. This is the first report that dietary PI increases serum adiponectin level and prevents the development of NAFLD in a rat model of the metabolic syndrome.  相似文献   

Effect of temperature on the development of eggs and the daily pattern of spawning of round herring <Emphasis Type="Italic">Etrumeus teres</Emphasis>     

Shinji Uehara  Takumi Mitani 《Fisheries Science》2009,75(1):159-165

Effect of temperature on the development of eggs of round herring Etrumeus teres was experimentally examined to construct a temperature-dependent egg development model. Mature fish were collected in the field and their eggs were artificially fertilized onboard. The eggs were incubated at nine temperatures set between 14.0 and 25.0°C. All eggs at the lowest three temperatures, 14.0°C, 15.0°C, and 16.0°C, ceased development and died at various stages before hatching. Durations required to hatching after fertilization ranged from 38.0 h at 25.0°C to 90.0 h at 17.5°C. The temperature-dependent egg development model, i.e., egg age in hours (y _i,t ) at the ith stage and temperature t (°C), was expressed as: y _i,t  = 4.604 × exp(−0.100 × t −0.129 × i) × i ^2.593. From the application of the model to early-stage eggs collected in the field, it is concluded that round herring starts spawning immediately after sunset and almost completes spawning by midnight. The temperature-dependent egg development model and the daily pattern of spawning presented in this study are essential tools for developing the daily egg production method to estimate the spawning stock biomass.  相似文献