Bipartite binding of the N terminus of Skp2 to cyclin A

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祁连山南麓高寒湿地生态系统呼吸季节、年际动态及影响因素

由于青藏高原高海拔、低温的特殊环境，使得生态系统呼吸(RE)对气候变化的响应极其敏感，然而对高寒湿地生态系统长时间尺度上的RE动态特征及驱动机制的研究相对薄弱。以青藏高原东北部高寒湿地为研究对象，分析了基于涡度相关系统观测的高寒湿地2004—2016年的CO₂通量排放动态及影响机制，对预测高寒湿地碳平衡对未来气候变化的响应具有重要意义。结果表明：高寒湿地在2004—2016年的月平均RE表现为单峰变化趋势，在8月达到峰值；年RE表现为逐年升高的趋势(P<0.05),年RE均值为(608.9±65.6) g C m^-2 a^-1;生长季RE约是非生长季RE的2.7倍，线性回归分析表明生长季RE(r~2=0.66,P=0.001)、非生长季RE(r~2=0.47,P=0.01)与全年RE呈极显著正相关。在月尺度上，分类回归树分析和线性回归分析表明土壤温度是月RE的最主要控制因素，暗示高寒湿地的土壤呼吸对整个生态系统的碳排放至关重要。在年际尺度上，生长季积温与生长季RE呈显著正相关(P<0.05),而生长季降水(PP...     

miR-34a is essential for p19Arf-driven cell cycle arrest

The Arf tumor suppressor gene product, p19^Arf, regulates cell proliferation in incipient cancer cells and during embryo development. Beyond its commonly accepted p53-dependent actions, p19^Arf also acts independently of p53 in both contexts. One such p53-independent effect with in vivo relevance includes its repression of Pdgfrβ, a process that is essential for vision in the mouse. We have utilized cell culture-based and mouse models to define a new role for miR-34a in this process. Ectopic expression of Arf in cultured cells enhanced the expression of several microRNAs predicted to target Pdgfrß synthesis, including the miR-34 family. Because miR-34a has been implicated as a p53-dependent effector, we investigated whether it also contributed to p53-independent effects of p19^Arf. Indeed, in mouse embryo fibroblasts (MEFs) lacking p53, Arf-driven repression of Pdgfrβ and its blockade of Pdgf-B stimulated DNA synthesis were both completely interrupted by anti-microRNA against miR-34a. Ectopic miR-34a directly targeted Pdgfrβ and a plasmid reporter containing wild-type Pdgfrβ 3′UTR sequence, but not one in which the miR-34a target sequence was mutated. Although miR-34a expression has been linked to p53—a well-known effector of p19^Arf—Arf expression and its knockdown correlated with miR-34a level in MEFs lacking p53. Finally, analysis of the mouse embryonic eye demonstrated that Arf controlled expression of miR-34a, and the related miR-34b and c, in vivo during normal mouse development. Our findings indicate that miR-34a provides an essential link between p19^Arf and its p53-independent capacity to block cell proliferation driven by Pdgfrβ. This has ramifications for developmental and tumor suppressor roles of Arf.     

Developmental strategies in Ectobius pallidus (Dictyoptera: Blattidae)

Ectobius pallidus has a semivoltine life cycle, overwintering as an egg and intermediate nymphal instar. A range of instars may overwinter, although the exact composition of an overwintering population varies annually. A number of developmental pathways are defined, involving both quiescence and diapause. The proportion of an instar following each pathway also varies annually. In ‘advanced’ years more 3rd and 4th instars enter diapause. The ecological significance of the different developmental strategies is discussed.     

Protein tyrosine kinase pathway-derived ROS/NO productions contribute to G2/M cell cycle arrest in evodiamine-treated human cervix carcinoma HeLa cells

Abstract

A previous study indicated that reactive oxygen species (ROS) and nitric oxide (NO) played pivotal roles in mediating cytotoxicity of evodiamine in human cervix carcinoma HeLa cells. This study suggested that G2/M cell cycle arrest was triggered by ROS/NO productions with regulations of p53, p21, cell division cycle 25C (Cdc25C), Cdc2 and cyclin B1, which were able to be prevented by protein tyrosine kinase (PTK) activity inhibitor genistein or JNK inhibitor SP600125. The decreased JNK phosphorylation by addition of Ras or Raf inhibitor, as well as the increased cell viability by addition of insulin-like growth factor-1 receptor (IGF-1R), Ras, Raf or c-Jun N-terminal kinase (JNK) inhibitor, further demonstrated that the Ras-Raf-JNK pathway was responsible for this PTK-mediated signalling. These observations provide a distinct look at PTK pathway for its suppressive effect on G2/M transition by inductions of ROS/NO generations.     

Chronobiology by moonlight

Most studies in chronobiology focus on solar cycles (daily and annual). Moonlight and the lunar cycle received considerably less attention by chronobiologists. An exception are rhythms in intertidal species. Terrestrial ecologists long ago acknowledged the effects of moonlight on predation success, and consequently on predation risk, foraging behaviour and habitat use, while marine biologists have focused more on the behaviour and mainly on reproduction synchronization with relation to the Moon phase. Lately, several studies in different animal taxa addressed the role of moonlight in determining activity and studied the underlying mechanisms. In this paper, we review the ecological and behavioural evidence showing the effect of moonlight on activity, discuss the adaptive value of these changes, and describe possible mechanisms underlying this effect. We will also refer to other sources of night-time light (‘light pollution’) and highlight open questions that demand further studies.     

Life cycle changes during 12 successive generations of laboratory colonisation of the leafroller Cnephasia jactatana (Walker) (Lepidoptera: Tortricidae) on artificial diet

Abstract

Close monitoring of the lepidopteran leafroller Cnephasia jactatana under laboratory colonisation revealed few distinct effects of successive rearing on artificial diet on the life cycle. The second laboratory generation had a prolonged development time and altered sex synchronism in pupation and eclosion patterns. Some deleterious changes were observed in later generations, including decreases in fertility, egg hatch and sperm motility, failure of mating adults to separate, and pupal and adult malformations. These changes were not adaptive, but were due to incompatibility with the general purpose diet (GPD) used; they were absent under sub-colonisation on a sheepnut-bean based diet (SBD). Success in the laboratory colonisation of C. jactatana is attributed to a random mating protocol, choice of environmental conditions representing the wild habitat, and a rapid rate of population growth.     

mTORC1 stimulates cell growth through SAM synthesis and m6A mRNA-dependent control of protein synthesis

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Light emitting diodes increase phenolics of buckwheat (Fagopyrum esculentum) sprouts

Abstract

Four types of light emitting diodes (LEDs) were used in three combinations (all blue [BBB], red: blue: far-red [RBFr]=4:1:1 and red: green: blue [RGB]=4:1:1) and seven irradiation cycles (12 h/12 h photoperiod, 1 Hz, 10 Hz, 100 Hz, 1 KHz, 10 KHz and 100 KHz) were applied to examine their effect on growth, stem color and phenolic compounds (homoorientin, orientin, rutin, vitexin and isovitexin) in buckwheat (Fagopyrum esculentum cv. Great Ruby) sprouts. With a few exceptions, among all the combinations and irradiation cycles of LEDs, the Great Ruby cultivar showed significant differences in total height and dry weight of sprouts. The study revealed that there was a direct effect of different combination and irradiation cycles of LEDs on sprout height and dry weight; and among the combinations, RBFr and BBB had more positive effect than RGB. Increasing irradiation cycles markedly decreased the red color of stalks of F. esculentum cv. Great Ruby sprouts, with no significant effect on leaf color. In sprouts, the rutin content of leaves and stalks was higher at 12 h photoperiod and the amount in leaves was 5–7% higher than that of stalks in all combinations and irradiation cycles of LEDs. Among polyphenols, the rutin content in stalks was 1.45–2.97 mg g^?1 dry weight and the maximum amount of rutin was obtained from RGB combination of LEDs. In leaves, higher amounts of homoorientin, orientin and vitexin+isovitexin were obtained from the RGB combination and there were significant differences between RGB and other two combinations of LEDs. On the other hand, in between the irradiation cycles used in the study, there were no significant differences for other polyphenols in leaves and stalks of buckwheat sprouts.