High-altitude tree growth responses to climate change across the Hindu Kush Himalaya

兴都库什喜马拉雅地区高海拔树木生长对气候变化的响应 高海拔地区快速升温可能导致树木对温度响应更为敏感,而限制高海拔地区树木生长的关键气候因子以及气候变化对树木生长产生多大程度的影响尚不清楚。本研究在兴都库什喜马拉雅地区收集了73 个样点的树轮数据,包括3个优势属的树种(Abies属、Juniperus属和Picea属),样点海拔均在3000 m以上。 将时间动态规整(dynamic time warping)的方法用于建立亚区域年表,以考虑不同站点年表之间变化的同步 性。同时,定量分析了气候因子对树木生长的贡献以及树木生长与气候因子关系的时空动态。研究结果发现,73个站点年表可以聚为3类,且与其所处的生物气候区相对应,即西喜马拉雅地区,中东喜马拉雅地区和藏东南地区。在干旱的西喜马拉雅地区,树木生长与冬、春两季的降水呈正相关关系,而在湿润的藏东南地区,树木生长与冬季温度和春季降水呈正相关关系。树木生长受最低温度的影响最大,特别是冬季温度,其重要性从西到东呈现递增趋势。滑动窗口相关分析表明,在中西喜马拉雅地区,影响树木生长的冬季温度信号在减弱,然而在藏东南地区该信号随着1980年以来的快速升温而增强。本研究结果表明,若该地区升温持续,在西喜马拉雅地区可能会因变暖引起的水分亏缺而造成森林衰退,而在藏东南地区因树木生长得益于变暖而使得森林扩张。     

Dopamine Receptor Microdomains Involved in Molecular Recognition and the Regulation of Drug Affinity and Function

A cationic protonatable amine moiety on dopaminergic ligands forms a high affinity reinforced ionic bond with an anionic aspartic acid at position 3.32 of dopamine receptors. When present, catechol hydroxyls of the ligands form hydrogen bonds with serines at position 5.42, 5.43, and 5.46, and this network of hydrogen bonds serves to orient ligands in the binding-site crevice and increase their binding affinity. A steric clash between aromatic moieties of the ligands and aromatic amino acids of the receptor (e.g., H6.55, F6.52 or F6.51 and W6.48) is likely to be propagated in domino-like fashion along the length of TM6, which is believed to trigger activation of the receptor. Specifically, it is the change in the conformation of W6.48 from an orientation perpendicular to the plane of the lipid membrane to one that is parallel that is believed to result in activation. Molecular determinants that mediate the D4/D2-selectivity of many extremely D4-selective 1,4-DAP ligands, include a nonconserved cluster of bulky amino acids at the TM2/TM3 interface (positions 2.61, 3.28 and 3.29).     

Leaf epidermis morphological differentiation between Tamarix africana Poir. and Tamarix gallica L. (Tamaricaceae) with ecological remarks

Abstract

Recent work, based on morphological and cytotaxonomical information, claimed the independence of Plantago brutia Ten., a narrow endemic of South Italy, with respect to Plantago media L. Here, we present a further evaluation of the systematic relationships occurring between these two taxa as revealed by molecular studies. We sampled P. brutia in most of the known populations and P. media in several European stands, from Sweden to the Iberian Peninsula and Balkans. We then investigated the relationships among the sampled populations by using as molecular markers the internal transcribed spacer regions ITS1 and ITS2. Furthermore, we considered cpDNA to gain further insight into the relationships among P. brutia/P. media populations. Based on nrDNA data, P. brutia appeared to be nested within the P. media complex, but as a well distinct subunit. This is congruent with a subspecific rank for this taxon within P. media. The cpDNA revealed the occurrence of several haplotypes in the studied material. Most of the assessed haplotypes were exclusive for single populations and thus phylogenetically uninformative. Nonetheless, we have found some haplotypes that are shared by different cytotypes or populations throughout the species range, suggesting possible explanations for the phylogenetic relationships occurring between P. brutia and the autopolyploid complex P. media.     

Structure-activity study of phosphoramido acid esters as acetylcholinesterasf inhibitors

Phosphoramido acid esters (CH₃)₂NP(O)X(p-OC₆H₄-CH₃) (containing P-Cl (1), P-O (2), P-F (3), P-CN (5), and P-N (4,6) bonds, X for 2, 4 and 6 is OCH₃, (C₂H₅)₂N and morpholin) have been synthesized to investigate the structure-activity study of AChE enzyme inhibition, through the parameters logP, δ³¹P and IC₅₀. After their characterization by ³¹P, ³¹P{¹H}, ¹³C, ¹H NMR, IR and mass spectroscopy, the parameters logP and δ³¹P (³¹P chemical shift in NMR) were used to evaluated the lipophilicity and electronical properties. The ability of compounds to inhibit human AChE was predicted by PASS software (version 1.193), and experimentally evaluated by a modified Ellman's assay.     

Crystal Structure and Conformation of 5‐Fluorouridine: Conformational Preferences for 5‐Fluorinated Pyranosides

Crystals of 5‐fluorouridine (5FUrd) have unit cell dimensions a = 7.716(1), b = 5.861(2), c = 13.041(1)Å, α = γ = 90°, β = 96.70° (1), space group P2₁, Z = 2, ρ_obs = 1.56 gm/c.c and ρ_calc = 1574 gm/c.c The crystal structure was determined with diffractometric data and refined to a final reliability index of 0.042 for the observed 2205 reflections (I ≥ 3σ). The nucleoside has the anti conformation [χ = 53.1(4)°] with the furanose ring in the favorite C2′–endo conformation. The conformation across the sugar exocyclic bond is g⁺, with values of 49.1(4) and ? 69.3(4)° for Φ_θc and Φ_∞ respectively. The pseudorotational amplitude τ_m is 34.5 (2) with a phase angle of 171.6(4)°. The crystal structure is stabilized by a network of N–H…O and O–H…O involving the N3 of the uracil base and the sugar O3′ and O2′ as donors and the O2 and O4 of the uracil base and O3′ oxygen as acceptors respectively. Fluorine is neither involved in the hydrogen bonding nor in the stacking interactions. Our studies of several 5‐fluorinated nucleosides show the following preferred conformational features: 1) the most favored anti conformation for the nucleoside [χ varies from ? 20 to + 60°] 2) an inverse correlation between the glycosyl bond distance and the χ angle 3) a wide variation of conformations of the sugar ranging froni C2′–endo through C3′–endo to C4′–exo 4) the preferred g⁺ across the exocyclic C4′–C5′ bond and 5) no role for the fluorine atom in the hydrogen bonding or base stacking interactions.     

“Length weight relationship of four non commercial fish species from the Southwest coast of India”

Length weight relationships (LWRs) were estimated for four species of low value fishes that belongs to four families from the southwest coast of India. The specimens of, Callionymus margaretae, Dactyloptena peterseni, Rogadius serratus and Minous inermis were collected for a period of 1 year from the fishing trawlers of Cochin Fisheries Harbour (Lat. 09° 56′ 327″ N, Long. 76° 15′ 764″ E). The estimated allometric coefficient b values ranged from 2.5020 (Rogadius serratus) to 3.2438 (Dactyloptena peterseni) and r² values ranged from 0.9492 (Rogadius serratus) to 0.9869 (Dactyloptena peterseni). All the LWRs were highly significant, with p < .001.This study provides the first estimate of LWRs for these low value by catch fish species.     

Length-weight relationships of eight fish from seagrass meadows in Wenchang,China

The length-weight relationships (LWRs) were studied for eight seagrass fish from Wenchang, China, using gill nets (150*1 m, mesh size 0.5 cm), including Gerres oblongus, Ambassis kopsii, Halichoeres nigrescens, Sillago aeolus, Yongeichthys criniger, Oxyurichthys tentacularis, Lethrinus haematopterus and Hypoatherina tsurugae, in November 2017, March and August 2018. Results suggest that mean LWR parameters b for these eight seagrass fish varied from 2.801 for L. haematopterus to 3.640 for A. kopsii, and r² valued from .950 for L. haematopterus to 0.993 for H. nigrescens. This study will help us to better understand the ecological parameters these seagrass fish.     

Secretory structures at syconia and flowers of Ficus enormis (Moraceae): A specialization at ostiolar bracts and the first report of inflorescence colleters

The fig (Ficus L.) infructescence, called syconium, is a receptacle with an apical opening, the ostiole, closed by bracts. The ostiolar bracts produce an exudate, which is rather conspicuous in some species. It has not been histochemically analyzed yet, and the structures responsible for its production are still unknown. Some wild growing species of Ficus from Brazil produce high amounts of this ostiolar exudate. Ficus enormis (Mart. ex Miq.) Miq. grows as trees or shrubs in the Atlantic rainforest. Our goal was to identify the secretory structures present in the inflorescence and, to characterize histochemically the ostiolar tissues and exudates. Syconia samples of F. enormis were processed and stained according to the usual techniques in plant anatomy. The morphological analysis revealed different types of bracts, one type specialized in secretion, another showing transitional characteristics between secretory and non-secreting bracts, and a third one being non-secreting. They are designated as secretory ostiolar bracts, transitional bracts and wall bracts. The floral bracteoles, digital-shaped colleters present in the ostiole, at the syconium axis and at the flower receptacle, were also analyzed. All have similar structure, like finger-shaped secretory trichomes. The colleters present among ostiolar bracts may contribute to production and composition of the ostiole exudate.     

The biology of the stoat (Mustela erminea) in the National Parks of New Zealand III. Morphometric variation in relation to growth,geographical distribution,and colonisation

Abstract

A total of 1599 stoats were collected from 14 study areas (including all 10 National Parks) from 1972 to 1976. Samples were larger in summer, and contained more females. Young stoats are born in September-October, and females reach adult weight by the following March, though males not until after August. There was significant geographic variation in the body size of adult stoats sampled: males from lowland podocarp/broadleaved forests averaged 3% smaller than males from upland beech forests in skull length, and 4% smaller in head-and-body length. This pattern was repeated, less clearly, in females and in young (approximately 2–5 months old). In contrast with stoats in Britain, assumed to be still the same size as the colonising stock introduced into New Zealand in 1884 and subsequently, males from lowland podocarp forests were unchanged or possibly smaller, and males from upland beech forests were larger; females were larger in all habitats. In males, the extent of geographic variation is almost as great in New Zealand as in the whole of continental Europe. Possible explanations of this pattern are discussed.