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Sawako Egusa Takayoshi Nishida Hiroichi Sawada & Kenji Fujisaki 《Entomologia Experimentalis et Applicata》2008,128(2):258-264
Plant-related performance may be one of the most important factors in the selection of host plants by insect herbivores. We investigated the importance of plant-related performance in host selection by the willow leaf beetle, Plagiodera versicolora (Laicharting) (Coleoptera: Chrysomelidae), on four willow species: Salix chaenomeloides Kimura, Salix eriocarpa Fr. et Sav., Salix integra Thunb., and Salix serissaefolia Kimura (Salicaceae). Bagging experiments in the field revealed that the performance of P. versicolora adults and larvae differed significantly among willow species under enemy-free conditions and at constant densities. Egg clutch and larval abundance were positively related to adult abundance. Plagiodera versicolora adults did not discriminate strongly among willow species for feeding and oviposition. Larval performance did not differ among willow species in the presence of natural enemies, suggesting that interspecific differences in host quality were overridden by mortality from natural enemies. Adult and egg clutch abundance of P. versicolora changed seasonally despite the temporal stability of adult and larval performance under enemy-free field conditions. Thus, plant-related performance of P. versicolora adults and larvae may contribute little to population growth and temporal dynamics of host use in P. versicolora . Potential factors that reduce discrimination of P. versicolora among host willow species are discussed. 相似文献
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The gelsolin family of proteins is a major class of actin regulatory proteins that sever, cap, and nucleate actin filaments in a calcium-dependent manner and are involved in various cellular processes. Typically, gelsolin-related proteins have three or six repeats of gelsolin-like (G) domain, and each domain plays a distinct role in severing, capping, and nucleation. The Caenorhabditis elegans gelsolin-like protein-1 (gsnl-1) gene encodes an unconventional gelsolin-related protein with four G domains. Sequence alignment suggests that GSNL-1 lacks two G domains that are equivalent to fourth and fifth G domains of gelsolin. In vitro, GSNL-1 severed actin filaments and capped the barbed end in a calcium-dependent manner. However, unlike gelsolin, GSNL-1 remained bound to the side of F-actin with a submicromolar affinity and did not nucleate actin polymerization, although it bound to G-actin with high affinity. These results indicate that GSNL-1 is a novel member of the gelsolin family of actin regulatory proteins and provide new insight into functional diversity and evolution of gelsolin-related proteins. 相似文献
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Ishida A Nakano T Yazaki K Matsuki S Koike N Lauenstein DL Shimizu M Yamashita N 《Oecologia》2008,156(1):193-202
We examined 15 traits in leaves and stems related to leaf C economy and water use for 32 co-existing angiosperms at ridge
sites with shallow soil in the Bonin Islands. Across species, stem density was positively correlated to leaf mass per area
(LMA), leaf lifespan (LLS), and total phenolics and condensed tannins per unit leaf N (N-based), and negatively correlated
to leaf osmotic potential and saturated water content in leaves. LMA and LLS were negatively correlated to photosynthetic
parameters, such as area-, mass-, and N-based assimilation rates. Although stem density and leaf osmotic potential were not
associated with photosynthetic parameters, they were associated with some parameters of the leaf C economy, such as LMA and
LLS. In the principal component (PCA) analysis, the first three axes accounted for 74.4% of total variation. Axis 1, which
explained 41.8% of the total variation, was well associated with parameters for leaf C and N economy. Similarly, axis 2, which
explained 22.3% of the total variation, was associated with parameters for water use. Axis 3, which explained 10.3% of the
total variation, was associated with chemical defense within leaves. Axes 1 and 2 separated functional types relatively well,
i.e., creeping trees, ruderal trees, other woody plants, C3 shrubs and forbs, palms, and CAM plants, indicating that plant functional types were characterized by similar attributes
of traits related to leaf C and N economy and water use. In addition, when the plot was extended by two unrelated traits,
leaf mass-based assimilation rates and stem density, it also separated these functional types. These data indicate that differences
in the functional types with contrasting plant strategies can be attributed to functional integration among leaf C economy,
hydraulics, and leaf longevity, and that both leaf mass-based assimilation rates and stem density are key factors reflecting
the different functions of plant species. 相似文献
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BACKGROUND AND AIMS: Leaf life span, photosynthetic parameters and defensive traits were compared across seven species of deciduous broad-leaved tree seedlings native to northern Japan to test the "cost-benefit hypothesis" that more productive leaves are more susceptible to herbivore attack than less productive leaves. METHODS: Studies were made on three early successional species, Alnus hirsuta, Betula maximowicziana and Betula platyphylla "japonica"; one mid-successional species, Ostrya japonica, and three late-successional species, Carpinus cordata, Quercus mongolica 'grosseserrata' and Acer mono. Photosynthetic parameters and defensive traits (total phenolics, condensed tannin and toughness) of leaves were measured for each species, and a bioassay test with Eri silkmoth larvae (Samia cynthia ricini) was undertaken to evaluate differences between species in susceptibility to herbivore attack. KEY RESULTS: Early successional species have a shorter leaf life span (62-88 d) than late successional species (155-187 d). Leaf nitrogen content and light-saturated photosynthetic rate per unit leaf area (P(sat)-area) and per unit leaf mass (P(sat)-mass) were negatively correlated with leaf life span. The nitrogen content of early successional species was about 30 mg g(-1) and that of late successional species was about 16 mg g(-1). Leaf toughness and the C/N ratio were positively correlated with leaf life span, although condensed tannin was not correlated with leaf life span. The bioassay test showed that the number of days the larvae survived was negatively correlated with leaf life span. Average survival of larvae feeding on leaves of A. hirsuta, which has the shortest leaf life span, was 14.4 d and that of Q. mongolica, which has the longest leaf life span, was 6.6 d. The number of days of larval survival was positively correlated with leaf nitrogen content. There was no correlation between days of larval survival and defensive traits. CONCLUSIONS: These results indicate that species with a shorter leaf life span have higher photosynthetic productivity and are more susceptible to herbivore attack than species with a longer leaf life span. This supports the "cost-benefit hypothesis". 相似文献
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Kudo T Nakayama E Suzuki S Akiyama M Shibata S 《American journal of physiology. Endocrinology and metabolism》2004,287(4):E644-E651
Myocardial infarction frequently occurs in the morning, a phenomenon in part resulting from the downregulation of fibrinolytic activity. Plasminogen activator inhibitor-1 (PAI-1) is a key factor behind fibrinolytic activity, and its gene expression is controlled under the circadian clock gene in the mouse heart and liver. Hypercholesterolemia has been associated with impaired fibrinolysis due to enhanced PAI-1 activity, which has also been implicated in atherosclerosis. The aim of this study was to decipher whether the Pai-1 gene is still expressed daily with hypercholesterolemia. Hypercholesterolemia (1% cholesterol diet) did not significantly affect the daily expression of clock genes (Per2 and Bmal1) and clock-controlled genes (Dbp and E4bp4) in the liver (P > 0.05); however, daily expression of the Pai-1 gene and Pai-1 promoter regulating factor genes such as Nr4a1 was significantly upregulated (P < 0.01). Daily restricted feeding for 4 h during the day reset the gene expression of Per2, Pai-1, Nr4a1, and Tnf-alpha. Lesion of the suprachiasmatic nucleus, the location of the main clock system, led to loss of Per2 and Pai-1 daily expression profiles. In the present experiments, we demonstrated that hypercholesterolemia enhanced daily expression of the Pai-1, Tnf-alpha, and Nr4a1 genes in the mouse liver without affecting clock and clock-controlled genes. Therefore, the risk or high frequency of acute atherothrombotic events in the morning still seems to be a factor that may be augmented under conditions of hypercholesterolemia. 相似文献
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Eriko Kage-Nakadai Hiroyuki Kobuna Osamu Funatsu Muneyoshi Otori Keiko Gengyo-Ando Sawako Yoshina Sayaka Hori Shohei Mitani 《BMC biotechnology》2012,12(1):1
Background
Transgenic strains of Caenorhabditis elegans are typically generated by injecting DNA into the germline to form multi-copy extrachromosomal arrays. These transgenes are semi-stable and their expression is silenced in the germline. Mos1 transposon or microparticle bombardment methods have been developed to create single- or low-copy chromosomal integrated lines. Here we report an alternative method using ultraviolet trimethylpsoralen (UV/TMP) to generate single/low-copy gene integrations. 相似文献60.
Actin-depolymerizing factor (ADF)/cofilin enhances the turnover of actin filaments by two separable activities: filament severing and pointed-end depolymerization. Multicellular organisms express multiple ADF/cofilin isoforms in a tissue-specific manner, and the vertebrate proteins are grouped into ADFs and cofilins on the basis of their biochemical activity. A recent comparative study has shown that ADF has greater severing and depolymerizing activities than cofilin [Chen, H., Bernstein, B. W., Sneider, J. M., Boyle, J. A., Minamide, L. S., and Bamburg, J. R. (2004) Biochemistry 43, 7127-7142]. Here, we show that the two Caenorhabditis elegans ADF/cofilin isoforms exhibit different activities for severing and depolymerizing actin filaments. The ADF-like non-muscle isoform UNC-60A had greater activities to cause net depolymerization and inhibit polymerization than the cofilin-like muscle isoform UNC-60B. Surprisingly, UNC-60B exhibited much stronger severing activity than UNC-60A, which was the opposite of what was observed for vertebrate counterparts. Moreover, UNC-60B induced much faster pointed-end depolymerization of rabbit muscle actin than UNC-60A, while UNC-60A caused slightly faster depolymerization of C. elegans actin than UNC-60B. These results suggest that cofilin-like UNC-60B is kinetically more efficient in enhancing actin turnover than ADF-like UNC-60A, while ADF-like UNC-60A is suitable for maintaining higher concentrations of monomeric actin. These functional differences might be specifically adapted for different actin dynamics in muscle and non-muscle cells. 相似文献