The Effects of Ferrous and other Ions on the Abiotic Formation of Biomolecules using Aqueous Aerosols and Spark Discharges

It has been postulated that the oceans on early Earth had a salinity of 1.5 to 2 times the modern value and a pH between 4 and 10. Moreover, the presence of the banded iron formations shows that Fe⁺² was present in significant concentrations in the primitive oceans. Assuming the hypotheses above, in this work we explore the effects of Fe⁺² and other ions in the generation of biomolecules in prebiotic simulation experiments using spark discharges and aqueous aerosols. These aerosols have been prepared using different sources of Fe⁺², such as FeS, FeCl₂ and FeCO₃, and other salts (alkaline and alkaline earth chlorides and sodium bicarbonate at pH = 5.8). In all these experiments, we observed the formation of some amino acids, carboxylic acids and heterocycles, involved in biological processes. An interesting consequence of the presence of soluble Fe⁺² was the formation of Prussian Blue, Fe₄[Fe(CN)₆]₃, which has been suggested as a possible reservoir of HCN in the initial prebiotic conditions on the Earth.     

Ecology of the rampant weed Nymphaea lotus L. Willdenow in natural and ricefield habitats of the Nile delta, Egypt

In a field study conducted around Lake Manzala (Egypt) during 1995–1996, the distribution of the floating-leafed lotus (Nymphaea lotus L.) in irrigation canals and ricefields was analyzed by classification and ordination methods. Environmental factors associated with its abundance and distribution were evaluated. A data set of 30 stands of lotus and nine environmental variables was analyzed by Canonical Correspondence Analysis (CCA) ordination relating environmental factors to the occurrence of the weed. Ordination analysis detected a strong association between soil organic matter and fine sediment (silt + clay) in the distribution of lotus. Water variables were less important. The density of lotus averaged 3.3±0.49 plants m−2 in the irrigation canals and 6.6±1.4 plants m−2 in the ricefields. The phytomass of lotus ranged from 877 g m−2 in the pure stands to 226 g m−2 in ricefield habitats. The highest proportion of lotus phytomass was allocated to leaf blade, with values reaching 40% of total phytomass in the infested ricefields. Allocation proportions to other plant organs varied between natural and ricefield habitats. Lotus plants allocated more dry matter to vegetative reproduction than to sexual reproduction. The ratio of vegetative to sexual reproduction ranged from 3.48 in the pure stands to 9.63 in infested ricefields. Populations of lotus showed wider variation in leaf area classes in pure stands than in rice stands. Presence of lotus as a weed in ricefields significantly reduced the growth and grain yield of the crop, indicating the risk of its spreading as an invasive weed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Characterisation by molecular hybridization of RNA fragments isolated from ancient (1400 B.C.) seeds

Summary The analysis of cress seeds from Thebes dated approximately 1400 years B.C. showed that fragments of RNA up to 10 bases in length were still present in the ancient seeds. After having been made radioactive at the 5OH terminus, the RNA fragments were used as probes in a spot hybridization experiment. They were shown to hybridize to cress DNA and, to a lesser extent, to that of phylogenetically distant species. When fixed onto nitrocellulose and probed with different cloned genes, the RNA fragments were shown to originate from breakage of the 25 and 18s cytoplasmic rRNA.     

Age-related climate sensitivity in Pinus Edulis at Dinosaur National Monument,Colorado, USA

The influence of tree age on climate sensitivity is of central importance in dendrochronology. Recent research has highlighted the disparate nature of age-dependent growth responses across species and geographic locations. We compared growth sensitivity and the influence of climate in Pinus edulis (Piñon) of varying ages at Dinosaur National Monument (DINO, northwestern Colorado, USA. Piñon is a particularly good species for this study because of its long life-span and climate sensitivity, and the DINO site is at the northern extreme of the current distribution. We evaluated changes in climate-growth relationships in piñon using total ring-width measurements and running averages of chronology statistics, mean sensitivity (MS) and coefficient of variation (CV), and we investigated growth response to climate variability as trees age. These measures indicated initial low growth sensitivity, increasing as trees reached mid-life stages, approximately 200–250 years, then relatively constant sensitivity from 250-800+ years. First order partial auto correlation (PAC1) declined throughout the life stages of piñon at DINO. The trend in declining autocorrelation leads to higher MS values in the older age classes. Greater year to year variation indicates less persistence in the study population, hence lower autocorrelation.We investigated the degree to which this relationship could be explained by the summer Palmer Drought Severity Index (PDSI) and whether this relationship varied with tree age. The strength of the tree-ring growth response to PDSI was at a maximum during the first two centuries of growth (R² = 0.54). between two and six centuries (R² = 0.48), after which we detected a decline in the sensitivity of tree growth to PDSI with increasing age (R² = 0.41). This study adds to the literature on age-related climate sensitivity in trees; our findings indicate that age-related changes in climate-tree-ring growth responses should be considered when climate variables are reconstructed from tree-ring width chronologies, and specifically from Pinus edulis.     

Immobilized Lotus tetragonolobus agglutinin binds oligosaccharides containing the Lex determinant

A defined set of oligosaccharides and glycopeptides containing -linked fucose were used to examine the specificity of the immobilized fucose-binding lectin Lotus tetragonolobus agglutinin (LTA1), also known as lotus lectin. Glycans containing the Lewis x determinant (Lex) Gal1-4[Fuc1-3]GlcNAc1-3-R were significantly retarded in elution from high density LTA-Emphaze columns. The lectin also bound the fucosylated lacdiNAc trisaccharide GalNAc1-4[Fuc1-3]GlcNAc. The lectin did not bind glycans containing either sialylLex or VIM-2 determinants, nor did it bind the isomeric Lea, Gal1-3[Fuc1-4]GlcNAc-R. Although 2-fucosyllactose Fuc1-2Gal1-4Glc) was retarded in elution from the columns, larger glycans containing the H-antigen Fuc1-2Gal1-3(4)GlcNAc-R interacted poorly with immobilized LTA. Our results demonstrate that immobilized LTA is effective in isolating glycans containing the Lex antigen and is useful in analyzing specific fucosylation of glycoconjugates. Abbreviations: LTA, Lotus tetragonolobus agglutinin; UEA-1, Ulex europaeus agglutinin-I; LNT, AAL, Aleuria aurantia agglutinin; Gal1-3GlcNAc1-3Gal1-3Glc; LNnT, Gal1-4GlcNAc1-3Gal1-3Glc; Lex, Lewis x antigen; Lea, Lewis a antigen; GDPFuc, guanosine 5-diphosphate--L-fucose     

莲子光下萌发过程中光合膜超分子结构与27kD多肽变化

冰冻撕裂电镜观察及膜多肽组分的研究结果表明,随着莲子在光下萌发时间的延长,莲(Nelumbonucifera Gaertn.)胚芽叶的叶绿体光合膜的超分子结构发育与膜多肽组分中的27kD多肽含量变化具有明显的相关性:1.萌发2d后,胚芽叶的叶绿体巨基位变成解垛叠状态,其光合膜的超分子结构只呈现解垛叠类囊体区外质膜撕裂面(EF)和解垛叠类囊体的原生质膜撕裂面(PF)两个面;膜组分中主要是30kD多肽,而27kD多肽含量甚微。2.萌发4d后,光合膜从解垛叠开始转变成小基粒垛,垛叠区类囊体外质膜撕裂面(EFs)和垛叠类囊体的原生质膜撕裂面(PFs)开始发育;27kD多肽含量开始增加,30kD多肽含量开始减少。3.萌发6～8d后,光合膜明显分化出非垛叠膜区,非垛叠类囊体的外质膜撕裂面(EFu)和非垛叠类囊体的原生质膜撕裂面(PFu)开始呈现,EFs和PFs功能蛋白颗粒逐渐增多;27kD多肽逐渐增加,30kD多肽逐渐减少。4.萌发10～12d后,光合膜垛叠和非垛叠膜区分化完善,排列有序,EFs、PFs、EFu和PFu面功能蛋白颗粒的密度、大小、分布等超分子构象发育正常;27kD多肽更加增多,30kD多肽几乎消失。表明其超分子结构的发育动态既与其超微结构变化相一致,又与27kD多肽含量变化相吻合,却与一般高等植物的叶绿体发育相反,可为显示莲在被子植物系统演化中的独特地位提     

Phylogenetic Position of Mammoth and Steller's Sea Cow Within Tethytheria Demonstrated by Mitochondrial DNA Sequences

Here we report DNA sequences from mitochondrial cytochrome b gene segments (1,005 base pairs per species) for the extinct woolly mammoth (Mammuthus primigenius) and Steller's sea cow (Hydrodamalis gigas) and the extant Asian elephant (Elephas maximus), the Western Indian manatee (Trichechus manatus), and the hyrax (Procavia capensis). These molecular data have allowed us to construct the phylogeny for the Tethytheria. Our molecular data resolve the trichotomy between the two species of living elephants and the mammoth and confirm that the mammoth was more closely related to the Asian elephant than to the African elephant. Our data also suggest that the sea cow–dugong divergence was likely as ancient as the dugong–manatee split, and it appears to have been much earlier (22 million years ago) than had been previously estimated (4–8 million years ago) by immunological comparison. Received: 8 August 1996 / Accepted: 30 September 1996     

中国古代人类麻风病和梅毒病的骨骼例证

文中记述了从中国不同时代考古遗址出土的人类麻风病和梅毒病骨骼标本的若干宏观病理特征,通过与国外资料对比,认为麻风病和梅毒病已经在秦汉时期的中国居民中传播,但是,目前至少还没有找到可靠病骨例证来证实麻风病和梅毒病均起源于中国。     

莲幼胚子叶细胞造淀粉体DNA的动态变化

莲(Nelumbo nucifera Gaertn.)幼胚子叶细胞造淀粉体和分离的造粉质体上均呈现强烈的 Feulgen 反应物质。经 DNA 酶处理后,在子叶细胞造淀粉体上呈 Feulgen 负反应。将分离的造粉质体用特异性的 DNA 荧光染料 DAPI 染色,造粉质体显示蓝色的荧光。实验证明,莲幼胚子叶细胞随着发育时期的增长,造粉质体 DNA 的含量逐渐增加,显示出有规律的动态变化过程。在电镜下观察,造粉质体 DNA 区域外无膜结构存在,故具有原核生物的特征。这种质体 DNA 的纤维丝直径大约为25。     

Postharvest senescence of fresh lotus pods and seeds is delayed by treatment with 1‐methylcyclopropene

Fresh lotus pods were treated with 1‐methylcyclopropene (1‐MCP) at a concentration of 0.5 μL L^?1 for 24 h at 25°C and then stored at 25°C for 8 days. First, their quality and physiological changes during storage were measured in terms of visual appearance, respiration rate, firmness, and the contents of sugars, protein, total phenolics and malondialdehyde (MDA). The results showed that the 1‐MCP treatment reduced the browning of fresh lotus pods, and inhibited the respiration rate during storage. In addition, the 1‐MCP treatment alleviated changes in firmness, delayed starch and protein degradation, and the accumulation of reducing sugars and total sugars in lotus seeds, preserving the good taste of lotus seeds. Moreover, the 1‐MCP treatment alleviated the increase of MDA and effectively inhibited the decrease in total phenolics in lotus seeds during days 6 to 8 of storage. Meanwhile, the results of antioxidant capacity in lotus seeds indicated that 1‐MCP not only sustained a higher level of 1,1‐diphenyl‐2‐picrylhydrazyl free radical scavenging activity, but also increased the activities of superoxide dismutase, catalase and peroxidase throughout the storage period. However, the 1‐MCP treatment reduced polyphenol oxidase activity in seeds relative to the control. Moreover, we found that the adenosine triphosphate content and energy charge during the last 4 days of storage were higher in 1‐MCP‐treated seeds than in the control. These results indicated that the use of 0.5 μL L^?1 1‐MCP provided an effective method, via multiple lines of evidence, to delay the postharvest senescence of fresh lotus pods and seeds.