Band reporting rates of waterfowl: does individual heterogeneity bias estimated survival rates?

In capture–recapture studies, the estimation accuracy of demographic parameters is essential to the efficacy of management of hunted animal populations. Dead recovery models based upon the reporting of rings or bands are often used for estimating survival of waterfowl and other harvested species. However, distance from the ringing site or condition of the bird may introduce substantial individual heterogeneity in the conditional band reporting rates (r), which could cause bias in estimated survival rates (S) or suggest nonexistent individual heterogeneity in S. To explore these hypotheses, we ran two sets of simulations (n = 1000) in MARK using Seber''s dead recovery model, allowing time variation on both S and r. This included a series of heterogeneity models, allowing substantial variation on logit(r), and control models with no heterogeneity. We conducted simulations using two different values of S: S = 0.60, which would be typical of dabbling ducks such as mallards (Anas platyrhynchos), and S = 0.80, which would be more typical of sea ducks or geese. We chose a mean reporting rate on the logit scale of −1.9459 with SD = 1.5 for the heterogeneity models (producing a back-transformed mean of 0.196 with SD = 0.196, median = 0.125) and a constant reporting rate for the control models of 0.196. Within these sets of simulations, estimation models where σ_S = 0 and σ_S > 0 (σ_S is SD of individual survival rates on the logit scale) were incorporated to investigate whether real heterogeneity in r would induce apparent individual heterogeneity in S. Models where σ_S = 0 were selected approximately 91% of the time over models where σ_S > 0. Simulation results showed < 0.05% relative bias in estimating survival rates except for models estimating σ_S > 0 when true S = 0.8, where relative bias was a modest 0.5%. These results indicate that considerable variation in reporting rates does not cause major bias in estimated survival rates of waterfowl, further highlighting the robust nature of dead recovery models that are being used for the management of harvested species.     

CD11c在新生儿及成人指皮组织表达的免疫组织化学研究

目的:研究新生儿及成人指皮组织CD11c阳性细胞的数量、形态和分布情况。方法:取7例尸检新生儿及5例成人无名指指皮组织样本,CD11c标记,行免疫组织化学染色,光镜观察阳性细胞的表达、分布情况并进行统计学分析。结果:人指皮组织中,CD11c阳性细胞和阳性突起呈棕褐色,胞体大小不等、形态多样;胞核呈圆形或椭圆形,突起长短粗细不等,可相互连接。阳性细胞呈散在或灶带状分布,灶带状分布常见于表皮乳头周围、血管神经分叉周围,血管外膜、环层小体被囊结缔组织内可见散在的CD11c阳性细胞。新生儿组CD11c阳性细胞的表达率为(31.0±9.4)%,高于成人组(6.0±2.7)%(P0.01)。结论:CD11c分子可能也是人指皮组织细胞分化过程中的阶段性标志物,其表达量的降低与年龄的增长有关。     

Different climate response of three tree ring proxies of Pinus sylvestris from the Eastern Carpathians,Romania

The aim of this study was to compare the climatic responses of three tree rings proxies: tree ring width (TRW), maximum latewood density (MXD), and blue intensity (BI). For this study, 20 cores of Pinus sylvestris covering the period 1886–2015 were extracted from living non-damaged trees from the Eastern Carpathian Mountains (Romania). Each chronology was compared to monthly and daily climate data. All tree ring proxies had a stronger correlation with the daily climate data compared to monthly data. The highest correlation coefficient was obtained between the MXD chronology and daily maximum temperature over the period beginning with the end of July and ending in the middle of September (r = 0.64). The optimal intervals for the temperature signature were 01 Aug – 24 Sept for the MXD chronology, 05 Aug – 25 Aug for the BI chronology, and both 16 Nov of the previous year – 16 March of the current year and 15 Apr – 05 May for the TRW chronology. The results from our study indicate that MXD can be used as a proxy indicator for summer maximum temperature, while TRW can be used as a proxy indicator for just March maximum temperature. The weak and unstable relationship between BI and maximum temperature indicates that BI is not a good proxy indicator for climate reconstructions over the analysed region.     

Environmental drivers interactively affect individual tree growth across temperate European forests

Forecasting the growth of tree species to future environmental changes requires a better understanding of its determinants. Tree growth is known to respond to global‐change drivers such as climate change or atmospheric deposition, as well as to local land‐use drivers such as forest management. Yet, large geographical scale studies examining interactive growth responses to multiple global‐change drivers are relatively scarce and rarely consider management effects. Here, we assessed the interactive effects of three global‐change drivers (temperature, precipitation and nitrogen deposition) on individual tree growth of three study species (Quercus robur/petraea, Fagus sylvatica and Fraxinus excelsior). We sampled trees along spatial environmental gradients across Europe and accounted for the effects of management for Quercus. We collected increment cores from 267 trees distributed over 151 plots in 19 forest regions and characterized their neighbouring environment to take into account potentially confounding factors such as tree size, competition, soil conditions and elevation. We demonstrate that growth responds interactively to global‐change drivers, with species‐specific sensitivities to the combined factors. Simultaneously high levels of precipitation and deposition benefited Fraxinus, but negatively affected Quercus’ growth, highlighting species‐specific interactive tree growth responses to combined drivers. For Fagus, a stronger growth response to higher temperatures was found when precipitation was also higher, illustrating the potential negative effects of drought stress under warming for this species. Furthermore, we show that past forest management can modulate the effects of changing temperatures on Quercus’ growth; individuals in plots with a coppicing history showed stronger growth responses to higher temperatures. Overall, our findings highlight how tree growth can be interactively determined by global‐change drivers, and how these growth responses might be modulated by past forest management. By showing future growth changes for scenarios of environmental change, we stress the importance of considering multiple drivers, including past management and their interactions, when predicting tree growth.     

Monooxygenation of aromatic compounds by flavin‐dependent monooxygenases

Many flavoenzymes catalyze hydroxylation of aromatic compounds especially phenolic compounds have been isolated and characterized. These enzymes can be classified as either single‐component or two‐component flavin‐dependent hydroxylases (monooxygenases). The hydroxylation reactions catalyzed by the enzymes in this group are useful for modifying the biological properties of phenolic compounds. This review aims to provide an in‐depth discussion of the current mechanistic understanding of representative flavin‐dependent monooxygenases including 3‐hydroxy‐benzoate 4‐hydroxylase (PHBH, a single‐component hydroxylase), 3‐hydroxyphenylacetate 4‐hydroxylase (HPAH, a two‐component hydroxylase), and other monooxygenases which catalyze reactions in addition to hydroxylation, including 2‐methyl‐3‐hydroxypyridine‐5‐carboxylate oxygenase (MHPCO, a single‐component enzyme that catalyzes aromatic‐ring cleavage), and HadA monooxygenase (a two‐component enzyme that catalyzes additional group elimination reaction). These enzymes have different unique structural features which dictate their reactivity toward various substrates and influence their ability to stabilize flavin intermediates such as C4a‐hydroperoxyflavin. Understanding the key catalytic residues and the active site environments important for governing enzyme reactivity will undoubtedly facilitate future work in enzyme engineering or enzyme redesign for the development of biocatalytic methods for the synthesis of valuable compounds.     

The growth ring concept: seeking a broader and unambiguous approach covering tropical species

The concept of growth rings is little discussed in the literature and their treatment remains somewhat confusing in terms of the diversity of structures described. This situation has a major impact on the study of growth rings in tropical species, in which variations and complexity are greater and accuracy of identification less good. The rigid conceptual delimitations used by dendrochronologists and wood anatomists of temperate regions cannot be applied to the study of growth rings in most tropical species, which has led to neglect of this subject. With the objective of discussing the concept of growth rings, the present study consists of a survey of anatomical, periodicity, causal and evolutionary aspects of the treatment of these structures as evidenced in previous studies, and the evaluation of their application and limitations to the development of this concept. Anatomical aspects arise through radial integrity, or the presence of early and late wood; the degree of distinction of the rings, which may vary from well to poorly defined; and tangential continuity, meaning that rings may form a complete circle in the transverse section of the trunk, or instead be tangentially discontinuous, lens‐shaped or in wedges. In addition there are a diversity of anatomical markers which enable us to recognize growth rings. Regarding periodicity, the rings may be annual, infra‐annual or supra‐annual. Causal aspects include genetic, endogenous and environmental components. Evolutionary aspects continue to be insufficiently investigated, and although most comparative studies treat growth rings recognized by different markers as though they were a single character, it remains questionable whether they can be regarded as homologous or the result of homoplasy. We conclude that the elaboration of a robust but broad definition which can include all the variation observed in growth rings of tropical species is a complex task, which is only possible by overcoming the restrictions adopted by dendrochronologists and wood anatomists of temperate regions for whom growth rings are essentially annual, strongly demarcated, tangentially continuous and restricted to the most pronounced markers.     

不同海拔温度和降水对新疆阿尔泰山西伯利亚落叶松径向生长的影响

为定量并分离关键气候因子对新疆阿尔泰山不同海拔树木径向生长的影响,通过对高、中和低海拔的西伯利亚落叶松(Larixsibirica)树轮宽度标准年表与气候因子分别进行相关、多元线性回归等统计分析,并进一步计算了线性模型中不同气候因素的绝对和相对贡献率。结果表明,高海拔地区,当年6月温度和上年7月降水分别与径向生长呈显著正相关和负相关,两者共同解释西伯利亚落叶松径向生长变异的33.1%,相对贡献率分别为66.2%和33.8%;中海拔地区,当年6月温度和上年6月降水分别与径向生长呈显著正相关和负相关,两者共同解释径向生长变异的26.8%,相对贡献率分别为40.1%和59.9%;低海拔地区,上年6月温度和7月降水分别与径向生长呈显著负相关和正相关,两者共同解释径向生长变异的29.4%,相对贡献率分别为31.9%和68.1%。这表明限制树木径向生长的主要影响因子随海拔的不同而异,在高海拔地区,温度是主要限制因子;而在低海拔地区,降雨是主要限制因子。     

多巴胺通过促进RNF20降解抑制神经细胞中组蛋白H2B泛素化

表观遗传修饰参与了药物成瘾的形成过程,而在药物成瘾过程中组蛋白泛素化水平的变化仍未可知。药物成瘾过程中常表现为多巴胺(dopamine, DA)表达量的升高,因此本研究欲探讨多巴胺升高对神经细胞组蛋白泛素化的影响及其机制。Western印迹结果显示,在终浓度0.8 mmol/L的多巴胺作用8 h后,人神经母细胞瘤细胞系SH-SY5Y细胞中环指蛋白20(ring finger protein 20, RNF20)表达量降低(0.29±0.032 vs. 1.0±0.025,P<0.0001),泛素化组蛋白H2B(H2Bub1)表达量下降(0.28±0.032 vs. 1.0±0.017,P<0.0001)。但是RT-PCR结果显示,多巴胺处理SH-SY5Y细胞后,RNF20在mRNA水平的表达无明显变化。在SH-SY5Y细胞中沉默RNF20的表达,H2Bub1在蛋白质水平的表达明显降低(0.20±0.069 vs. 1.0±0.060,P=0.001)。在加入多巴胺的基础上,分别加入蛋白酶体抑制剂MG132、自噬体形成抑制剂3-MA以及空泡型H^+-ATP酶特异性抑制剂Baf-A1等药物来检测RNF20的降解途径,结果发现,加入MG132、3-MA以及Baf-A1后,RNF20表达量均比DA处理组显著上升(1.51±0.095,P=0.0003; 0.89±0.075,P=0.0021; 2.74±0.099,P<0.0001;vs. 0.27±0.044)。上述结果表明,在SH-SY5Y细胞中,RNF20对H2Bub1具有调控作用,多巴胺可通过泛素化及自噬两种途径促进RNF20降解,从而抑制组蛋白H2B泛素化。     

Two species of the Rhodiola yunnanensis species complex distributed around the Sichuan Basin of China: Speciation in a ring?

A ring species consists of two reproductively isolated forms connected by a chain of intergrading populations encircling a geographic barrier. The mountains encircling the Sichuan Basin in southwestern China harbor great species diversity and endemism, and they are candidate regions for ring species. Here, we examined a potential ring species complex with a ring distribution surrounding the Sichuan Basinand the reproductive barrier between sibling species Rhodiola yunnanensis and R. henryi of the R. yunnanensis complex. In this study, we test the hypothesis that R. yunnanensis and R. henryi diverged by the ring-species model using an amplicon sequencing strategy targeting the introns of 27 single-copy nuclear genes and 14 chloroplast DNA sequences. Our studies indicated that the R. yunnanensis complex is monophyletic, originates at the late Miocene, and forms its current ring distribution pattern after the LIG. In addition, clear genetic intergradation was not found among R. henryi populations within the distribution ring. All these findings suggest that the divergence of two sibling species was not driven by the geographic isolation, and they were not originated from the ring-species model; however, the basin-surrounding distribution pattern and reproductive barrier between them meet some criteria for being a ring species.     

Differentiation of the anomeric configuration and ring form of glucosyl-glycolaldehyde anions in the gas phase by mass spectrometry: isomeric discrimination between m/z 221 anions derived from disaccharides and chemical synthesis of m/z 221 standards

Mass spectrometry of disaccharides in the negative-ion mode frequently generates product anions of m/z 221. With glucose-containing disaccharides, dissociation of isolated m/z 221 product ions in a Paul trap yielded mass spectra that easily differentiated between both anomeric configurations and ring forms of the ions. These ions were shown to be glucosyl-glycolaldehydes through chemical synthesis of their standards. By labeling the reducing carbonyl oxygen of disaccharides with 18O to mass discriminate between monosaccharides, it was established that the m/z 221 ions are comprised solely of an intact nonreducing sugar with a two-carbon aglycon derived from the reducing sugar, regardless of the disaccharide linkage position. This enabled the anomeric configuration and ring form of the ion to be assigned and the location of the ion to the nonreducing side of a glycosidic linkage to be ascertained. Detailed studies of experimental factors necessary for reproducibility in a Paul trap demonstrated that the unique dissociation patterns that discriminate between the isomeric m/z 221 ions could be obtained from month-to-month in conjunction with an internal energy-input calibrant ion that ensures reproducible energy deposition into isolated m/z 221 ions. In addition, MS/MS fragmentation patterns of disaccharide m/z 341 anions in a Paul trap enabled linkage positions to be assigned, as has been previously reported with other types of mass spectrometers.