Geotaxis and leaf-surface preferences mitigate negative effects of a predatory mite on an herbivorous mite.

Reproductive success and population growth of an herbivorous mite are limited by activities of phytoseiid predators. However, occurrences on upper versus lower leaf surfaces are sometimes mismatched between these prey and predators. The mismatch potentially mitigates predation risk for the prey species. We assessed factors that affect mite distributions on leaf surfaces, testing whether the presence of the phytoseiid mite Phytoseius nipponicus alters the leaf-surface distribution and reproductive success of the herbivorous false spider mite Brevipalpus obovatus. The host plant was Viburnum erosum var. punctatum (Adoxaceae). Leaves were set in natural (TRUE) and reversed (upside down; INVERTED) orientations using experimental devices. Both surfaces were accessible to mites. We detected lower and abaxial leaf-surface preferences in P. nipponicus. In contrast, upper and adaxial surfaces were preferred by B. obovatus. Thus, prey and predatory mites accumulated on different sides of leaves. Presence of the predator also indirectly decreased egg production in B. obovatus. Brevipalpus obovatus females actively avoided leaf surfaces with elevated predator numbers; these females shifted their distributions and changed oviposition sites to leaf surfaces with fewer predators. In consequence, B. obovatus eggs on the upper sides of leaves were less frequently preyed upon than were those on lower sides. We suggest that upper leaf-surface exploitation in this particular herbivorous mite species mitigates predation risk from phytoseiid mites, which prefer lower leaf surfaces

好塩基球からのヒスタミン遊離に関する研究. 1 自動分析装置による全血からのヒスタミン遊離の測定

Histamine released from whole blood was determined by an automated fiuorometric histamine analysis system. The increased release of histamine from basophils by anti-IgE was observed in ten healthy subjects and 12 extrinsic asthma patients, while the release in 11 intrinsic asthma patients was significantly less as compared to that in healthy and extrinsic asthma subjects. House dust extract caused a significant increase in the histamine release from basophils of the extrinsic asthma patients who are sensitive to house dust. It was concluded from this study that histamine released from basophils could be easily determined by an automated analysis system and that the method is useful for the diagnosis and study of allergy.ヒスタミン自動分析装置により,健康人10名,気管支喘息23例の全血からのヒスタミン遊離を測定した. 抗ヒトIgEを添加した際のヒスタミン遊離は,健康人および外因性気管支喘息症例では有意の増加傾向を示したが,一方内因性喘息症例では遊離増加はほとんどみられなかった. ハウスダスト抗原添加では,ハウスダストが抗原である気管支喘息症例においてのみ全血からの有意のヒスタミン遊離の増加が観察された. 以上の結果より,ヒスタミン自動分析装置による全血からの遊離ヒスタミンの測定は,気管支喘息の病態解明の1手段として極めて有用であると考えられる

Genome-Wide DNA Methylation Analysis Reveals Phytoestrogen Modification of Promoter Methylation Patterns during Embryonic Stem Cell Differentiation

BACKGROUND: Environmental challenges during development affect the fetal epigenome, but the period(s) vulnerable to epigenetic dysregulation is(are) not clear. By employing a soy phytoestrogen, genistein, that is known to alter the epigenetic states of the A(vy) allele during embryogenesis, we have explored the sensitive period for epigenetic regulation. The post-implantation period, when de novo DNA methylation actively proceeds, is amenable to in vitro analysis using a mouse embryonic stem (ES) cell differentiation system. METHODS AND FINDINGS: Mouse ES cells were differentiated in the presence or absence of genistein, and DNA methylation patterns on day 10 were compared by microarray-based promoter methylation analysis coupled with a methylation-sensitive endonuclease (HpaII/McrBC)-dependent enrichment procedure. Moderate changes in methylation levels were observed in a subset of promoters following genistein treatment. Detailed investigation of the Ucp1 and Sytl1 promoters further revealed that genistein does not affect de novo methylation occurring between day 0 and day 4, but interferes with subsequent regulatory processes and leads to a decrease in methylation level for both promoters. CONCLUSION: Genistein perturbed the methylation pattern of differentiated ES cells after de novo methylation. Our observations suggest that, for a subset of genes, regulation after de novo DNA methylation in the early embryo may be sensitive to genistein

好塩基球からのヒスタミン遊離に関する研究. 2. ハウスダスト抗原および抗ヒトIgEによるヒスタミン遊離

IgE-mediated release of histamine from whole blood was examined in two healthy and four asthmatic subjects by dose-dependent fashion. The significantly increased amount of histamine was released from basophils of both healthy and asthmatic subjects by a limited concentration of anti-IgE. Antigen (house dust) caused histamine release only from basophils of asthmatics who are sensitive to house dust. Basophils from one patients with asthma released no significant amount of histamine by anti-IgE.好塩基球からのIgE-mediated histamine releaseの機序を,健康人(2名)および気管支喘息(4例)それぞれの代表例で比較検討した. 抗ヒトIgEの添加濃度別検討では,健康人および外因性喘息例いずれも有意のヒスタミン遊離の増加をしめしたが,Max. % histamine releaseをひきおこす抗ヒトIgEの濃度は比較的限られた範囲内にある傾向がみられた. 一方内因性喘息例では,いずれの抗ヒトIgE濃度でも有意のヒスタミン遊離はみられなかった. ハウスダスト抗原の添加濃度別検討では,ハウスダストが抗原である気管支喘息症例においてdose-dependentなヒスタミン遊離が観察されたが,使用された抗原濃度の範囲ではMax. % releaseをひきおこす至適濃度は明らかでなかった

好塩基球からのヒスタミン遊離に関する研究. 3. 抗ヒトIgE に対する好塩基球の反応性と末梢血好酸球増多

Histamine release from basophils induced by anti-IgE was examined in 14 asthmatic subjects with blood eosinophilia. The subjects were divided into two groups; group I (with blood eosinophilia, positive skin test and positive RAST to house dust) and group II (with blood eosinophilia, negative skin test to various allergens and negative RAST to house dust). 1. Serum IgE levels in group I were much higher than those in group II. 2. Maximum percent histamine release induced by anti-IgE was much higher in group I than in group II. 3. Dose-response curve of anti-IgE-induced histamine release in group I showed consistent increase as anti-IgE concentrations increased. while, dose-response curve in group II was very low. These findings suggested that blood eosinophilia in group I might be elicited relating to IgE-mediated reaction. However, mechanism causing eosinophilia in group II was not clear in the present study.末梢血好酸球増多を示す気管支喘息14症例について,抗ヒトIgE による好塩基球からのヒスタミン遊離を検討した. ハウスダストに対する皮内反応およびRASTが陽性を示す症例群(groupI)では,血清IgE値が高く,また抗ヒトIgEによるMax. % ヒスタミン遊離も高く(50.7士5.0%),そのdoseresponse curveは抗ヒトIgE添加濃度が高くなるにつれて上昇する傾向を示した.一方種々のアレルゲンエキスに対する皮内反応が陰性で,かつRAST も陰性を示す症例群(group II)では,血清IgE値が低く,また抗ヒトIgEによるMax. % ヒスタミン遊離も低く(10.5士1.7%),そのdose-response curveは全般的に低く,抗ヒトIgE添加濃度が高いところではむしろ抑制される傾向を示した

葉の上下面における環境異質性がダニの捕食-被食関係に及ぼす影響

京都大学0048新制・課程博士博士(農学)甲第18312号農博第2037号新制||農||1020(附属図書館)学位論文||H26||N4819(農学部図書室)31170京都大学大学院農学研究科地域環境科学専攻(主査)教授 天野 洋, 教授 田中 千尋, 教授 松浦 健二学位規則第4条第1項該当Doctor of Agricultural ScienceKyoto UniversityDFA

Stellate hairs on leaves of a deciduous shrub Viburnum erosum var. punctatum (Adoxaceae) effectively protect Brevipalpus obovatus (Acari: Tenuipalpidae) eggs from the predator Phytoseius nipponicus (Acari: Phytoseiidae).

The eggs of the herbivorous false spider mite Brevipalpus obovatus Donnadieu have a longer incubation period than those of spider mites and are not protected by webs. Brevipalpus obovatus often lays its eggs in the gaps among the hairs on host leaves. We examined the effects of stellate hairs of Viburnum erosum var. punctatum (VEP) leaves on the survival of B. obovatus eggs. Adult B. obovatus and Phytoseius nipponicus Ehara, a generalist predator, were introduced to VEP leaf disks; each B. obovatus egg was inspected daily until hatching. More eggs (63 vs. 42 %) survived on the abaxial surfaces of VEP leaves, where the stellate hairs are more complicated, than on the adaxial surfaces. Predation hazard decreased rapidly with increasing egg age and a substantial portion of the eggs hatched. Phytoseius nipponicus preyed on eggs regardless of egg age when mixed-age eggs were provided. Manipulative experiments with bent stellate hairs showed that the normal hairs reduced the predation risk of B. obovatus eggs by P. nipponicus. Therefore, the predation hazard was considered to decrease since the stellate hairs hindered the search for B. obovatus eggs by the phytoseiid mite

Do plant mites commonly prefer the underside of leaves?

The adaxial (upper) and abaxial (lower) surfaces of a plant leaf provide heterogeneous habitats for small arthropods with different environmental conditions, such as light, humidity, and surface morphology. As for plant mites, some agricultural pest species and their natural enemies have been observed to favor the abaxial leaf surface, which is considered an adaptation to avoid rain or solar ultraviolet radiation. However, whether such a preference for the leaf underside is a common behavioral trait in mites on wild vegetation remains unknown. The authors conducted a 2-year survey on the foliar mite assemblage found on Viburnum erosum var. punctatum, a deciduous shrub on which several mite taxa occur throughout the seasons, and 14 sympatric tree or shrub species in secondary broadleaf-forest sites in Kyoto, west-central Japan. We compared adaxial-abaxial surface distributions of mites among mite taxa, seasons, and morphology of host leaves (presence/absence of hairs and domatia). On V. erosum var. punctatum, seven of 11 distinguished mite taxa were significantly distributed in favor of abaxial leaf surfaces and the trend was seasonally stable, except for Eriophyoidea. Mite assemblages on 15 plant species were significantly biased towards the abaxial leaf surfaces, regardless of surface morphology. Our data suggest that many mite taxa commonly prefer to stay on abaxial leaf surfaces in wild vegetation. Oribatida displayed a relatively neutral distribution, and in Tenuipalpidae, the ratio of eggs collected from the adaxial versus the abaxial side was significantly higher than the ratio of the motile individuals, implying that some mite taxa exploit adaxial leaf surfaces as habitat

freqpcr: Estimation of population allele frequency using qPCR ΔΔCq measures from bulk samples

野外の生物集団の遺伝子頻度を効率よく推定する統計モデルを開発 --複数個体を一括して抽出したサンプルにおけるDNA量の個体差に対処する--. 京都大学プレスリリース. 2022-10-12.PCR techniques, both quantitative (qPCR) and nonquantitative, have been used to estimate the frequency of a specific allele in a population. However, the labour required to sample numerous individuals and subsequently handle each sample renders the quantification of rare mutations (e.g., pesticide resistance gene mutations at the early stages of resistance development) challenging. Meanwhile, pooling DNA from multiple individuals as a “bulk sample” combined with qPCR may reduce handling costs. The qPCR output for a bulk sample, however, contains uncertainty owing to variations in DNA yields from each individual, in addition to measurement errors. In this study, we have developed a statistical model to estimate the frequency of the specific allele and its confidence interval when the sample allele frequencies are obtained in the form of ΔΔCq in the qPCR analyses on multiple bulk samples collected from a population. We assumed a gamma distribution as the individual DNA yield and developed an R package for parameter estimation, which was verified using real DNA samples from acaricide-resistant spider mites, as well as a numerical simulation. Our model resulted in unbiased point estimates of the allele frequency compared with simple averaging of the ΔΔCq values. The confidence intervals suggest that dividing the bulk samples into more parts will improve precision if the total number of individuals is equal; however, if the cost of PCR analysis is higher than that of sampling, increasing the total number and pooling them into a few bulk samples may also yield comparable precision

Seasonal changes in the deleterious effects of solar ultraviolet-B radiation on eggs of the twospotted spider mite, Tetranychus urticae (Acari: Tetranychidae)

Solar ultraviolet-B (UVB) radiation has deleterious effects on plant-dwelling mites. We assessed the biological effects of UVB radiation on the eggs of the twospotted spider mite, Tetranychus urticae Koch, under both near ambient (UV+) and UV-attenuated (UV−) conditions from spring to autumn and compared them to the effects of temperature and humidity. The ambient daily UVB irradiance increased from January to August and then decreased rapidly until December, whereas egg hatchability under UV+ was lowest in April (10.7%) and increased almost linearly until October (74.9–92.3%). In contrast, hatchability under UV− was consistently high (96.2–99.8%) through all seasons. For UV+, the stepwise multiple linear regression analysis supported the negative correlation of hatchability with cumulative UVB irradiance during egg periods (cumulative dose), but did not support that with the mean daily UVB irradiance (dose rate), suggesting that UVB-induced mortality in T. urticae eggs is cumulative dose dependent rather than dose rate dependent. The high mortality in April may have reflected the slower development caused by the relatively lower temperature and higher UVB radiation, increasing the cumulative dose, while the low mortality in October may have reflected the faster development caused by the relatively higher temperature and lower UVB radiation, decreasing the cumulative dose