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41.
Zong S Wang Z Luo Y Zang J Wen J 《Zeitschrift für Naturforschung. C, Journal of biosciences》2011,66(11-12):621-626
We determined the mechanisms underlying host selection by adults of the seabuckthorn carpenterworm, Holcocerus hippophaecolus Hua, Chou, Fang et Chen. Four sea buckthorn (Hippophae rhamnoides L.) subspecies (varieties) with different degrees of resistance to H. hippophaecolus were chosen for artificial insect infection in cages. The results showed that olfactory and visual cues are very important for the selection of host plants by H. hippophaecolus, but that olfactory stimuli play a more vital role in this process. The relative abundance of branches and leaves had no effect on the likelihood that adults landed on plants from four subspecies (varieties), but did influence landing rates within the same subspecies (varieties). When considering only the most resistant sea buckthorn subspecies (varieties), the presence of luxuriant branches and leaves led to lower landing rates. These results provide a theoretical basis for the understanding of H. hippophaecolus damage to sea buckthorn and the means to implement effective measures of control. 相似文献
42.
Lawren VandeVrede Ramy Abdelhamid Zhihui Qin Jaewoo Choi Sujeewa Piyankarage Jia Luo John Larson Brian M. Bennett Gregory R. J. Thatcher 《PloS one》2013,8(8)
Selective estrogen receptor modulators (SERMs) are effective therapeutics that preserve favorable actions of estrogens on bone and act as antiestrogens in breast tissue, decreasing the risk of vertebral fractures and breast cancer, but their potential in neuroprotective and procognitive therapy is limited by: 1) an increased lifetime risk of thrombotic events; and 2) an attenuated response to estrogens with age, sometimes linked to endothelial nitric oxide synthase (eNOS) dysfunction. Herein, three 3rd generation SERMs with similar high affinity for estrogen receptors (ERα, ERβ) were studied: desmethylarzoxifene (DMA), FDMA, and a novel NO-donating SERM (NO-DMA). Neuroprotection was studied in primary rat neurons exposed to oxygen glucose deprivation; reversal of cholinergic cognitive deficit was studied in mice in a behavioral model of memory; long term potentiation (LTP), underlying cognition, was measured in hippocampal slices from older 3×Tg Alzheimer''s transgenic mice; vasodilation was measured in rat aortic strips; and anticoagulant activity was compared. Pharmacologic blockade of GPR30 and NOS; denudation of endothelium; measurement of NO; and genetic knockout of eNOS were used to probe mechanism. Comparison of the three chemical probes indicates key roles for GPR30 and eNOS in mediating therapeutic activity. Procognitive, vasodilator and anticoagulant activities of DMA were found to be eNOS dependent, while neuroprotection and restoration of LTP were both shown to be dependent upon GPR30, a G-protein coupled receptor mediating estrogenic function. Finally, the observation that an NO-SERM shows enhanced vasodilation and anticoagulant activity, while retaining the positive attributes of SERMs even in the presence of NOS dysfunction, indicates a potential therapeutic approach without the increased risk of thrombotic events. 相似文献
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The RhoA/ROCK-2 signaling pathway is necessary for activated hepatic stellate cell (HSC) contraction. HSC contraction plays an important role in the pathogenesis of cirrhosis and portal hypertension. This study investigated whether aldosterone contributes to HSC contraction by activation of the RhoA/ROCK-2 signaling pathway. Primary HSCs were isolated from Sprague-Dawley rats via in situ pronase/collagenase perfusion. We found that aldosterone enhanced the contraction of a collagen lattice seeded with HSCs. This induced contraction was suppressed by the mineralcorticoid receptor (MR) inhibitor spironolactone, the ROCK-2 inhibitor Y27632, and the angiotensin II type 1 receptor (AT(1)R) inhibitor irbesartan. Moreover, actin fiber staining showed that aldosterone significantly increased actin fiber formation in HSCs. Pre-incubating with spironolactone, Y27632, or irbesartan inhibited the aldosterone-induced actin fiber reorganization. Molecularly, the effect of aldosterone on activation of HSC contraction was mediated by phosphorylated myosin light chain (P-MLC) through the RhoA/ROCK-2 signaling pathway. All these inhibitors had the ability to block aldosterone-induced protein expressions in the RhoA/ROCK-2/P-MLC cascade in HSCs. Taken together, our current study suggests that aldosterone induces contraction of activated HSCs through the activation of the RhoA/ROCK-2 signaling pathway. This finding may provide a potential therapeutic target for control of cirrhosis and portal hypertension. 相似文献
45.
Mammary epithelial cells undergo structural and functional differentiation at late pregnancy and parturition to produce and secrete milk. Both TGF-β and prolactin pathways are crucial regulators of this process. However, how the activities of these two antagonistic pathways are orchestrated to initiate lactation has not been well defined. Here, we show that SnoN, a negative regulator of TGF-β signaling, coordinates TGF-β and prolactin signaling to control alveologenesis and lactogenesis. SnoN expression is induced at late pregnancy by the coordinated actions of TGF-β and prolactin. The elevated SnoN promotes Stat5 signaling by enhancing its stability, thereby sharply increasing the activity of prolactin signaling at the onset of lactation. SnoN(-/-) mice display severe defects in alveologenesis and lactogenesis, and mammary epithelial cells from these mice fail to undergo proper morphogenesis. These defects can be rescued by an active Stat5. Thus, our study has identified a new player in the regulation of milk production and revealed a novel function of SnoN in mammary alveologenesis and lactogenesis in vivo through promotion of Stat5 signaling. 相似文献
46.
Yalan Chen Zhangliu Du Zhe Weng Ke Sun Yuqin Zhang Qin Liu Yan Yang Yang Li Zhibo Wang Yu Luo Bo Gao Bin Chen Zezhen Pan Lukas Van Zwieten 《Global Change Biology》2023,29(18):5445-5459
To achieve long-term increases in soil organic carbon (SOC) storage, it is essential to understand the effects of carbon management strategies on SOC formation pathways, particularly through changes in microbial necromass carbon (MNC) and dissolved organic carbon (DOC). Using a 14-year field study, we demonstrate that both biochar and maize straw lifted the SOC ceiling, but through different pathways. Biochar, while raising SOC and DOC content, decreased substrate degradability by increasing carbon aromaticity. This resulted in suppressed microbial abundance and enzyme activity, which lowered soil respiration, weakened in vivo turnover and ex vivo modification for MNC production (i.e., low microbial carbon pump “efficacy”), and led to lower efficiency in decomposing MNC, ultimately resulting in the net accumulation of SOC and MNC. In contrast, straw incorporation increased the content and decreased the aromaticity of SOC and DOC. The enhanced SOC degradability and soil nutrient content, such as total nitrogen and total phosphorous, stimulated the microbial population and activity, thereby boosting soil respiration and enhancing microbial carbon pump “efficacy” for MNC production. The total C added to biochar and straw plots were estimated as 27.3–54.5 and 41.4 Mg C ha−1, respectively. Our results demonstrated that biochar was more efficient in lifting the SOC stock via exogenous stable carbon input and MNC stabilization, although the latter showed low “efficacy”. Meanwhile, straw incorporation significantly promoted net MNC accumulation but also stimulated SOC mineralization, resulting in a smaller increase in SOC content (by 50%) compared to biochar (by 53%–102%). The results address the decadal-scale effects of biochar and straw application on the formation of the stable organic carbon pool in soil, and understanding the causal mechanisms can allow field practices to maximize SOC content. 相似文献
47.
Liming Yan Yiqi Luo Rebecca A. Sherry Jesse E. Bell Xuhui Zhou Jianyang Xia 《Global Change Biology Bioenergy》2014,6(5):556-565
The efficiency of a terrestrial ecosystem to use rainfall in production is critical in regulating the ecological functions of the earth system under global change. However, it remains unclear how rain use efficiency (RUE) will be altered by changes in climate and human activities such as biofuel harvest. In this study, we used RUE data from a long‐term experiment in a tallgrass prairie to analyze the effects of warming and biofuel harvest (clipping). From 2000 to 2011, experimental warming enhanced RUE in most years, with larger positive effects in normal and wet than dry hydrological years. Clipping decreased RUE in dry and normal hydrological years, but had no impact on RUE in wet years. The observed RUE responses resulted from treatment‐induced changes in both biologically ineffective (i.e., runoff and soil evaporation) and effective (i.e., transpiration) parts of precipitation. For example, litter cover was increased in warming plots, but reduced by clipping, leading to negative and positive effects on runoff and soil evaporation, respectively. The dominance of C4 species, which usually have higher water use efficiency than C3 species, was enhanced by warming, but reduced by clipping. Moreover, RUE was positively correlated with ratios of rainfall in the late growing season (June–August), when the growth of C4 plants was most active, relative to that in the other seasons. Our results indicate that RUE is positively influenced by climate warming, but negatively affected by biofuel harvest in tallgrass prairie of the Great Plains. These findings highlight the important roles of plant community structure and temporal distribution of precipitation in regulating ecosystem RUE. 相似文献
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49.
柠檬醛损伤黄曲霉线粒体生化机理的研究 总被引:18,自引:2,他引:18
应用生物化学方法并结合扫描电镜,研究柠檬醛掺入黄曲霉细胞,并通过损伤线粒体(Mt),导致抑制其生长的机理。结果表明,在药物致敏浓度时,菌丝体经该醛作用后,胞内Mt呈不规则增多,氧化还原反应系统受到破坏,与对照组相比,柠檬醛组的琥珀酸脱氢酶(Succinate Dehydrogenase,SDH)、苹果酸脱氢酶(Malate Dehydrogenase,MDH)活性分别呈不可逆下降271%和242%,随着药物浓度的升高,SDH、MDH的活性直至消失;以琥珀酸、α酮戊二酸和丙酮酸为底物时,线粒体呼吸速率分别下降24.1%、14.3%和36.1%,提示柠檬醛能使菌丝体DNA、RNA、脂类和蛋白质等生物合成受到抑制,促进细胞死亡。 相似文献
50.
RPB1 and RPB2, which encode the largest and second largest subunits of RNA polymerase II, respectively, are essential single copy genes in fungi, animals and most plants. Two paralogs of the RPB2 gene have been found in some groups of angioperms [Oxelman, B., Yoshikawa, N., McConaughy, B.L., Luo, J., Denton, A.L., Hall, B.D., 2004. RPB2 gene phylogeny in flowering plants, with particular emphasis on asterids. Mol. Phylogenet. Evol. 32, 462-479]. Here, we report the results of experiments designed to identify the evolutionary origin of the RPB2 duplicate copies. Through careful sampling and phylogenetic analysis, we were able to construct the RPB2 gene tree in angiosperms and infer the phylogenetic positions of the gene duplication and gene loss events that occurred. Our study shows that an RPB2 gene duplication occurred early in core eudicot evolution, at or near the time of the Buxaceae/Trochodendraceae divergence. Subsequently, multiple gene duplication and paralog sorting events happened independently in different core eudicot taxa. Differential expression of the two RPB2 gene paralogs may explain the preservation of both paralogs in the asterids. One gene (RPB2-i) accounts for most of the RPB2 mRNA made in the flower organs while the other gene (RPB2-d) is predominantly used in the vegetative tissues. We also found two paralogs of the RPB1 gene in some core eudicot species. The RPB1 gene duplication occurred before core eudicot divergence, around the time of RPB2 gene duplication. Several independent RPB1 paralog sorting events happened in different core eudicot taxa; their occurrence was independent of the RPB2 paralog sorting events. Our results suggest that a polyploidization event happened at or near the time of the Buxaceae/Trochodendraceae divergence. We propose that this polyploidization and the partial diploidization processes thereafter may have been the driving force of core eudicot radiation. 相似文献