Perception of UV-B by the Arabidopsis UVR8 protein     

Rizzini L  Favory JJ  Cloix C  Faggionato D  O'Hara A  Kaiserli E  Baumeister R  Schäfer E  Nagy F  Jenkins GI  Ulm R 《Science (New York, N.Y.)》2011,332(6025):103-106

To optimize their growth and survival, plants perceive and respond to ultraviolet-B (UV-B) radiation. However, neither the molecular identity of the UV-B photoreceptor nor the photoperception mechanism is known. Here we show that dimers of the UVR8 protein perceive UV-B, probably by a tryptophan-based mechanism. Absorption of UV-B induces instant monomerization of the photoreceptor and interaction with COP1, the central regulator of light signaling. Thereby this signaling cascade controlled by UVR8 mediates UV-B photomorphogenic responses securing plant acclimation and thus promotes survival in sunlight.  相似文献   

The role of nutrients for improving seedling quality in drylands   总被引：2，自引：0，他引：2  

Jordi Cortina  Alberto Vilagrosa  Roman Trubat 《New Forests》2013,44(5):719-732

Forest plantations have been extensively used to combat desertification. In drylands, harsh climate conditions and unfertile soils often preclude seedling establishment. The improvement in seedling quality by manipulating nutrient availability could contribute to increase planting success. However, morpho-functional traits defining optimum seedling quality in drylands, and the fertilization schemes to achieve them, are still under discussion. Several studies suggest that well fertilized seedlings may perform better than nutrient limited seedlings in these environments. However, recent works have shown opposite results. In this review, we discuss the concept of seedling quality in drylands based on an evaluation of the effects of nutrient manipulation on seedling morpho-functional traits and field performance. According to existing data, we hypothesize that nutrient-limited small seedlings may be better adapted to arid environments and unfavorable microsites, where access to water is uncertain and a conservative water use strategy may be advantageous. In contrast, in dry sub-humid areas, areas with deep soils, protected from excess radiation, and areas where irrigation is feasible, well-fertilized big seedlings with high root growth potential may have more chances of success. We discuss this theory in the context of the multiple objectives of dryland restoration and the environmental constrains posed by these areas, and identify knowledge gaps that should be targeted to test our hypothesis.  相似文献   

Ileal absorption of L-carnitine from diets used in reproductive polar fox (Alopex lagopus L.) nutrition     

Roman Szymeczko  Katarzyna Burlikowska  Christine Iben  Anna Piotrowska  Monika Bogusławska-Tryk 《Acta Agriculturae Scandinavica, Section A - Animal Sciences》2013,63(3):142-147

Abstract

Five mature ileorectal anastomosed blue foxes (6.18±0.15 kg) were used in digestibility experiments to evaluate the L-carnitine apparent ileal absorption from diets used in reproductive polar fox nutrition over the year-long farm-feeding period on two domestic farms (A and B) differing in reproduction results. The concentration of L-carnitine was higher in diets from farm B (136.1–241.7 mg kg^?1 DM) than in the diets from farm A (88.5–135.2 mg kg^?1 DM). The coefficients of ileal apparent absorption of L-carnitine ranged from 60.23 to 75.57% for diets A (farm A) composed mainly of fish and poultry offals. The coefficients of ileal apparent digestibility of L-carnitine were higher for diets B (farm B) (83.75–94.78%; P<0.05) based on beef offals. These data indicate high concentration and efficient ileal apparent absorption of L-carnitine from diets used in reproductive polar fox nutrition on both farms examined.  相似文献   

Sociodemographic, behavioural and environmental correlates of sweetened beverage consumption among pre-school children     

Pabayo R  Spence JC  Cutumisu N  Casey L  Storey K 《Public health nutrition》2012,15(8):1338-1346

  相似文献   

Computational Assessment of Chito-Oligosaccharides Interactions with Plasma Proteins     

Diana Larisa Roman  Vasile Ostafe  Adriana Isvoran 《Marine drugs》2021,19(3)

It is widely rec ognized that chitin and chitosan are potential sources of bioactive materials and that their oligosaccharides reveal various biological activities (including antimicrobial) that are correlated with their structures and physicochemical properties. This study uses the molecular docking approach to assess the interactions of small chito-oligosaccharides (MW< 1500 Da) with plasma proteins in order to obtain information regarding their fate of distribution in the human organism. There are favorable interactions of small chito-oligomers with plasma proteins, the interactions with human serum albumin being stronger than those with α-1-acid glycoprotein. The interaction energies increase with increasing the molecular weight, decrease with increasing deacetylation degrees and are reliant on the deacetylation pattern. This study could inform the application of chito-oligosaccharides with varying molecular weights, degrees, and patterns of deacetylation in human health.  相似文献   

Triterpene Glycosides from the Far Eastern Sea Cucumber Thyonidium (=Duasmodactyla) kurilensis (Levin): The Structures,Cytotoxicities, and Biogenesis of Kurilosides A3, D1, G,H, I,I1, J,K, and K1     

Alexandra S. Silchenko  Anatoly I. Kalinovsky  Sergey A. Avilov  Pelageya V. Andrijaschenko  Roman S. Popov  Pavel S. Dmitrenok  Ekaterina A. Chingizova  Vladimir I. Kalinin 《Marine drugs》2021,19(4)

Nine new mono-, di-, and trisulfated triterpene penta- and hexaosides, kurilosides A₃ (1), D₁ (2), G (3), H (4), I (5), I₁ (6), J (7), K (8), and K₁ (9) and two desulfated derivatives, DS-kuriloside L (10), having a trisaccharide branched chain, and DS-kuriloside M (11), having hexa-nor-lanostane aglycone with a 7(8)-double bond, have been isolated from the Far-Eastern deep-water sea cucumber Thyonidium (=Duasmodactyla) kurilensis (Levin) and their structures were elucidated based on 2D NMR spectroscopy and HR-ESI mass-spectrometry. Five earlier unknown carbohydrate chains and two aglycones (having a 16β,(20S)-dihydroxy-fragment and a 16β-acetoxy,(20S)-hydroxy fragment) were found in these glycosides. All the glycosides 1–9 have a sulfate group at C-6 Glc, attached to C-4 Xyl1, while the positions of the other sulfate groups vary in different groups of kurilosides. The analysis of the structural features of the aglycones and the carbohydrate chains of all the glycosides of T. kurilensis showed their biogenetic relationships. Cytotoxic activities of the compounds 1–9 against mouse neuroblastoma Neuro 2a, normal epithelial JB-6 cells, and erythrocytes were studied. The highest cytotoxicity in the series was demonstrated by trisulfated hexaoside kuriloside H (4), having acetoxy-groups at C(16) and C(20), the latter one obviously compensated the absence of a side chain, essential for the membranolytic action of the glycosides. Kuriloside I₁ (6), differing from 4 in the lacking of a terminal glucose residue in the bottom semi-chain, was slightly less active. The compounds 1–3, 5, and 8 did not demonstrate cytotoxic activity due to the presence of hydroxyl groups in their aglycones.  相似文献   

Food selection of burbot (Lota lota L.) larvae reared in illuminated net cages in mesotrophic Lake Maróz (north-eastern Poland)     

Grażyna Furgała-Selezniow  Andrzej Skrzypczak  Dariusz Kucharczyk  Roman Kujawa  Andrzej Mamcarz  Daniel Żarski  Katarzyna Targońska 《Aquaculture International》2014,22(1):41-52

Feeding and food selection of burbot (Lota lota L.) larvae reared in illuminated cages were studied. The experiment was carried out in mesotrophic Lake Maróz, in north-eastern Poland, for 6 weeks in two successive years. The initial stocking density was 1,250 larvae (20 DPH) per cage. Food selection according to the zooplankton groups (Rotifera, Cladocera and Copepoda) and length classes was expressed by the Strauss linear selectivity index (L). Zooplankton species composition in the lake was similar in the two seasons of the study and organisms shorter than 0.5 mm prevailed in the plankton. The mean number of prey found in burbot alimentary tracts increased from about 40 up to over 200 during the course of the study. A very large inter-individual variation in the amount of food organisms consumed by fish was noted. Analysis of the values of the Strauss food selectivity index shows that at the beginning of the first year of the experiment, burbot larvae preferred copepods, most numerous in the environment at that time; later, fish tended to select cladocerans. In the second year of the study, fish more often ate copepods, irrespective of their quantities in the environment. During the whole study, reared burbot larvae did not eat rotifers, even when they were numerous in cages. Similarly to the rotifers, the smallest planktonic organisms, measuring up to 0.5 mm in length, were typically neglected by fish, while the 0.6–1.0 mm group was most frequently selected. There were also considerable individual differences between particular burbot specimens in their food preferences.  相似文献   

Maternal oxytocin triggers a transient inhibitory switch in GABA signaling in the fetal brain during delivery     

Tyzio R  Cossart R  Khalilov I  Minlebaev M  Hübner CA  Represa A  Ben-Ari Y  Khazipov R 《Science (New York, N.Y.)》2006,314(5806):1788-1792

We report a signaling mechanism in rats between mother and fetus aimed at preparing fetal neurons for delivery. In immature neurons, gamma-aminobutyric acid (GABA) is the primary excitatory neurotransmitter. We found that, shortly before delivery, there is a transient reduction in the intracellular chloride concentration and an excitatory-to-inhibitory switch of GABA actions. These events were triggered by oxytocin, an essential maternal hormone for labor. In vivo administration of an oxytocin receptor antagonist before delivery prevented the switch of GABA actions in fetal neurons and aggravated the severity of anoxic episodes. Thus, maternal oxytocin inhibits fetal neurons and increases their resistance to insults during delivery.  相似文献   

杜鹃对两种远距离的近缘苇莺的巢寄生:一个平行协同进化的案例?(英文)     

Csaba MOSKAT  Fugo TAKASU  A.Roman MU 《中国鸟类》2012,3(4):320-329

大杜鹃(Cuculus canorus)通常寄生小型雀形目鸟类。由于杜鹃雏鸟的排他性拱卵或拱雏,导致宿主繁殖失败,因此宿主进化出如卵识别能力的反寄生策略。反过来,杜鹃也同时进化出如模拟宿主卵的寄生策略。于是两者之间的相互作用可形成类似军备竞赛的协同进化关系。在匈牙利,大苇莺(Acrocephalus arundinaceus)是大杜鹃的主要宿主,寄生率可高达约 40-65%。以往被认为是大苇莺一个亚种的东方大苇莺(A. orientalis)在日本的种群也被大杜鹃寄生(25-40%)。通过采用光纤光谱仪量化大杜鹃及其宿主的卵色特征,我们比较了东、西半球大杜鹃对两种苇莺的寄生模拟程度。鸟类视觉模型显示,对于可见光颜色,杜鹃与宿主之间卵色的模拟程度在匈牙利高于日本,但匈牙利杜鹃和宿主均较大的卵色变异程度可导致卵色模拟困难。杜鹃与苇莺卵色的量度差异在日本较低,这被证明是宿主拒卵行为的一个重要影响因素。苇莺对大杜鹃卵的拒绝率在日本(35%)和匈牙利(37%)相似。与匈牙利不同,在日本,宿主对杜鹃寄生的应对策略如拒卵行为,先于杜鹃的反适应对策。我们认为,两种近缘物种大苇莺对杜鹃寄生的不同反寄生行为,代表了协同进化军备竞赛的不同演化阶段。  相似文献   

Forest fires and vegetation during the Holocene in central Yakutia, eastern Siberia     

Fumitaka Katamura  Masami Fukuda  Nikolai P. Bosikov  Roman V. Desyatkin 《Journal of Forest Research》2009,14(1):30-36

In order to investigate the relationship between vegetation change and fire history in the Siberian boreal forest, fossil pollen and charcoal from two lakes in central Yakutia, eastern Siberia, were analyzed. The vegetation change inferred from the pollen analysis was similar to that found in previous research in the region. Open larch forest covered this region during the late Glacial and early Holocene periods. Later, during the mid-Holocene, Scots pine expanded its range. The low levels of charcoal in the lake deposits represent surface forest fires, suggesting that the present-day surface fire regime has been taking place since at least 6,500 calibrated years before the present (cal yr BP) and that stand-replacing fire has not occurred during the Holocene. Larch and Scots pine forests, which are characterized by surface fire regimes, have been predominant since the early Holocene.  相似文献