科尔沁沙地不同密度小叶锦鸡儿灌丛水量平衡研究

根据沙地水分平衡理论推算了不同栽植密度下小叶锦鸡儿灌丛的蒸散量.结果表明,小叶锦鸡儿灌丛生长期土壤水分含量随着植被密度增加而降低,0.5 m×1 m、1 m×2 m密度植被区平均土壤含水量低于凋萎湿度(1.55%),2 m×2 m密度植被和天然小叶锦鸡儿植被平均土壤含水量保持在1.60%以上,能够满足植被生存和生长的水分需求.蒸散量随着植被密度增加而增大,以0.5 m×1 m密度灌丛区最高,为297.81 mm,占同期降水量的97.90%;2 m×2 m密度灌丛区最低,为279.71 mm,生长期末期土壤水分节余为24.49 mm.依据生长期土壤水分状况和水分平衡要求,科尔沁沙地小叶锦鸡儿灌丛适宜密度应为2 m×2 m.     

Diurnal variation of the delta 13C of pine needle respired CO2 evolved in darkness

The delta 13C of pine needle CO2 evolved in darkness (delta 13Cr) for slash pine trees (Pinus elliottii) was determined by placing recently collected pine needles in darkness and collecting respired CO2 over a short time period (<15 min). Delta 13Cr measurements were made over several 24 h periods to test the hypothesis that significant variation in delta 13Cr would be observed during a diurnal cycle. The delta 13Cr measurements from the 24 h time series trials showed a consistent midday 13C-enrichment (5-10 per thousand) relative to bulk biomass. The delta 13Cr values became more 13C-depleted at night and following shading, and approached bulk-biomass delta 13C values by dawn. The effect of night-time respired 13C-enriched CO2 on the delta 13C value of the remaining assimilate is shown to be minimal (13C depleted by 0.22 per thousand) under field conditions for P. elliottii needles.     

Breeding Population of the Ringed Plover in Britain

A census of Ringed Plovers in Britain in 1973–74 revealed a total of over 5,700 pairs, with the best concentrations in eastern England (particularly in Norfolk and Essex), the Outer Hebrides, Orkney and Shetland. Some interesting recent changes in habitat are chronicled.     

Roles of microRNAs in pressure overload- and ischemia-related myocardial remodeling

Cardiac remodeling, a term that spans maladaptation at the molecular, cellular, tissue and organ levels, is the key pathophysiological process that leads to heart failure (HF). In clinic, pressure overload and ischemia are the two most common reasons to induce cardiac remodeling and HF, which includes but is not limited to cardiac hypertrophy, fibrosis, and cardiomyocyte apoptosis. MicroRNAs (miRNAs) are endogenous, single-stranded, short non-coding RNAs. By imperfectly binding to the 3′ untranslated region (UTR) of messenger RNAs (mRNAs), miRNAs are able to suppress target gene expression by promoting degradation or by inhibiting translation of the target mRNAs, thus playing an important role in a wide range of biologic processes. Growing evidence has indicated that miRNAs are aberrantly expressed in the cardiovascular system under experimental and clinical conditions with cardiac remodeling and HF. Clinically there is increasing evidence that miRNAs can act as diagnostic biomarker and even represent a novel therapeutic target in several cardiovascular disorders. This review provides an overview of several miRNAs' impacts in pressure-overload and ischemia-induced cardiac remodeling and HF.     

Impacts of Environmental Colloids on the Transport of 17 β-estradiol in Intact Soil Cores

Estrogens such as 17-β estradiol (E2) are endocrine-disrupting compounds and can affect the reproductive systems of aquatic organisms. Therefore, it is important to understand the mechanisms of their transport in the environment. E2 and its daughter product estrone (E1) are both strongly adsorbed by soil organic matter and have relatively short half-lives. Reduced contact time with soil makes transport of E2 and E1 in soil more likely. In this study, intact soil cores from three soils representing a range of particle size distribution, structure, and organic matter content were used to compare the transport of E2 with and without the presence of colloidal material fractionated from soil or swine manure. In chemical transport experiments conducted with undisturbed soil columns, E2 and E1 were measured both in solution and attached to suspended solids in column effluent. During the transport experiments, colloids carrying E2 passed through all soils, with the exception of the sandy soil. The presence of colloids decreased the first detection time of E2 in the aqueous phase, was correlated with greater peak E2 concentrations in the effluent of both loamy and clayey soils, but not through the sandy soil, and increased mass fractions of the E2 that was transported.     

西藏乃东县发现豆雁

正2016年1月6日,在西藏自治区乃东县泽当镇羌哉村(29°16′29.634″N,95°49′44.202″E,海拔3 557 m)观察到2只雁,该雁全身以灰褐色为主,尾下覆羽为白色,脚为橙黄色,喙黑色、喙端有黄斑,嘴甲和鼻孔间有白色斑点,两胁具灰褐色黄斑。经鉴定为豆雁(Anser fabalis)(约翰·马敬能等2000,Mark 2009,曲利明2014)。查阅相关文献(中国科学院青藏高原综合科学考察队1983,赵正阶2001,郑光美2011,刘迺发等2013),确认     

Understanding variation in salamander ionomes: A nutrient balance approach

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Positive selection driving the evolution of a gene of male reproduction, Acp26Aa, of Drosophila: II. Divergence versus polymorphism

The evolution of the gene for a male ejaculatory protein, Acp26Aa, has been shown to be driven by positive selection when nonsibling species in the Drosophila melanogaster subgroup are compared. To know if selection has been operating in the recent past and to understand the details of its dynamics, we obtained DNA sequences of Acp26Aa and the nearby Acp26Ab gene from 39 D. melanogaster chromosomes. Together with the 10 published sequences, we analyzed 49 sequences from five populations in four continents. The southern African population is somewhat differentiated from all other populations, but its nucleotide diversity is lower at these two loci. We find the following results for Acp26Aa: (1) The R: S (replacement : silent changes) ratio is significantly higher in the between-species comparisons than in the within-species data by the McDonald and Kreitman test. Positive selection is probably responsible for the excess of amino acid replacements between species. (2) However, within-species nucleotide diversity is high. Neither the Tajima test nor the Fu and Li test indicates a reduction in nucleotide diversity due to positive selection in the recent past. (3) The newly derived nucleotides in D. melanogaster are at high frequency significantly more often than predicted by the neutral equilibrium. Since the nearby Acp26Ab gene does not show these patterns, these observations cannot be attributed to the characteristics of this chromosomal region. We suggest that positive selection is active, but may be weak, for each amino acid change in the Acp26Aa gene.