Species Diversity and Altitudinal Gradient Patterns of Evergreen Broad leaved Forest in MeihuashanNational Natural Reserve,Fujian Province

In China, evergreen broad leaved forests (EBLFs) is one of the most important vegetation types which was widly distributed in subtropical area, and it plays a very important role in the global biological diversity and natural environment conservation also. In order to reveal species diversity and altitudinal gradient patterns of evergreen broad leaved forest in Meihuashan National Natural Reserve, Fujian Province. Five altitude transects were set up at a vertical interval of 200m between 375m and 1300m above sea level in the EBLFs distribution areas, and twenty four quadrats(14400m2) had been surveyed. Species richness(S), species richness index (dGl), Simpson index (D), Shannon Wiener index (H′), Pielou evenness index (J) had been used for analysis of species diversity and altitudinal gradient pattern of EBLFs. The average value of S, dGl, H′,J and D were 64.42, 10.75, 5.75, 3.50, 0.58 respectively. The difference of community species diversity index(S, dGl, D, H′, and J) was extremely significant between transects, and the altitudinal gradient patterns of species diversity presented the unimodal variable trend, with a peak in the mid altitude(700m-900m). The species richness and Shannon Wiener index of different layer were ranked as shrub layer (include young tree and the plants between layers)>arbor layer>herb layer. The species richness of tree and shrub layer, and Shannon Wiener index of tree layer were significantly different between at transects, and trends of altitude gradient was similar to community. The Shannon Wiener index of shrub layer and herb layer, and the species richness of herb layer did not change significantly along elevation gradient. Therefore, plant species diversity distribution pattern presented a unimodal variable trend along an elevation gradient, and supported “mid domain model” in EBLFs of Meihuashan National Nature Reserve.     

云雾山铁杆蒿茎叶浸提液对封育草地四种优势植物的化感效应

为了揭示铁杆蒿群落在植被演替中的作用,通过研究铁杆蒿茎叶浸提液对铁杆蒿草地4种优势植物(百里香、大针茅、本氏针茅和赖草)的种子萌发及幼苗生长的干扰,结果表明:高浓度的铁杆蒿浸提液(甲醇浸提液和水浸提液)使得百里香、大针茅、本氏针茅和赖草的种子发芽指数降低,发芽率、芽长和根长低于对照,种子平均发芽时间延长达1.13-2.16 d。而低浓度浸提液(0.005 g/mL)使得百里香的发芽要高于对照11.63%(水浸提液)、15.12%(甲醇浸提液)。在幼苗生长期,铁杆蒿浸提液对4种受试植物幼苗芽和根的生长受到不同程度的抑制,不同浓度的浸提液对植物的化感作用强度不同,随浓度的增加,抑制作用越强,0.1 g/mL相对其他浓度有显著性差异;其中0.005 g/mL浸提液对本氏针茅和赖草的幼苗生长有促进作用,幼根生长高出对照19.00%、16.06%,水浸提液对幼芽促进了2.33%、9.06%,在0.1 g/mL浓度下,本氏针茅或大针茅的生长完全受到抑制,芽长和根长抑制率为100%;同一浓度下的不同浸提液对植物的抑制作用也不同,其中百里香对铁杆蒿浸提液的敏感度是最低的;甲醇浸提液的化感作用要强于水浸提液。在封育过程中,百里香群落向铁杆蒿群落的过渡,铁杆蒿的化感作用是该草地演替的一个重要影响因子。     

On the Crucial Stages in the Origin of Animate Matter

Theories of the origin of life have proposed hypotheses to link inanimate to animate matter. The theory proposed here derived the crucial stages in the origin of animate matter directly from the basic properties of inanimate matter. It asked what were the general characteristics of the link, rather than what might have been its chemical details. Life and its origin are shown to be one continuous physicochemical process of replication, random variation, and natural selection. Since life exists here and now, animate properties must have been initiated in the past somewhere. According to the theory, life originated from an as yet unknown elementary autocatalyst which occurred spontaneously, then replicated autocatalytically. As it multiplied to macroscopic abundance, its replicas gradually exhausted their reactants. Random chemical drift initiated diversity among autocatalysts. Diversity led to competition. Competition and depletion of reactants slowed down the rates of net replication of the autocatalysts. Some reached negative rates and became extinct, while those which stayed positive ``survived.' Thus chemical natural selection appeared, the first step in the transition from inanimate to animate matter. It initiated the first animate property, fitness, i.e., the capacity to adapt to the environment and to survive. As the environment was depleted of reactants, it was enriched with sequels—namely, with decomposition products and all other products which accompany autocatalysis. The changing environment exerted a selective pressure on autocatalysts to replace dwindling reactants by accumulating sequels. Sequels that were incorporated into the autocatalytic process became internal components of complex autocatalytic systems. Primitive forms of metabolism and organization were thus initiated. They evolved further by the same mechanism to ever higher levels of complexity, such as homochirality (handedness) and membranal enclosure. Subsequent evolution by the same mechanism generated cellular metabolism, cell division, information carriers, and a genetic code. Theories of self-organization without natural selection are refuted. Received: 29 March 1996 / Accepted: 30 May 1996     

Expression of zeta molecules is decreased in NK cells from HIV-infected patients

Cytolysis by natural killer (NK) cells is impaired in HIV infection. We investigated whether the expression of zeta (zeta) molecules, essential elements of signalling initiated upon ligation of, e.g., CD16, is reduced and if so, whether this reduction could be involved in defective cytolysis. FACS analysis revealed significantly lower levels of zeta in NK cells from AIDS patients compared to cells from patients without AIDS and healthy controls. CD16-dependent cytolysis by NK cells correlated with expression of zeta molecules and CD16, the latter possibly related to zeta expression. No correlation was observed between CD16-independent cytolysis and zeta expression. Reduced expression of zeta molecules by NK cells from HIV-infected patients thus correlates with disease progression and may, in part, explain the defective cytolysis by these cells.     

Natural sway frequencies and damping ratios of trees: concepts,review and synthesis of previous studies

Previous studies that measured the natural frequencies and damping ratios of conifer trees were reviewed and results synthesized. Analysis of natural frequency measurements from 602 trees, belonging to eight different species, showed that natural frequency was strongly and linearly related to the ratio of diameter at breast height to total tree height squared (i.e., DBH/H ²). After accounting for their size, pines (Pinus spp.) were found to have a significantly lower natural frequency than both spruce (Picea spp.) and Douglas-fir (Pseudotsuga spp.). Natural sway frequencies of de-branched trees were significantly higher than those of the same trees with the branches intact, and the difference increased with an increasing ratio of DBH/H ². Damping mechanisms were discussed and methods for measuring damping ratio were presented. Analysis of available data suggested that internal damping ratios were typically less than 0.05 and were not related to tree diameter. External damping was mainly due to aerodynamic drag on the foliage and contact between the crowns of adjacent trees. Analysis of data from previous wind-tunnel studies indicated that damping due to aerodynamic drag is a nonlinear function of velocity. Damping due to crown contact has been suggested by a previous author to be a function of both the distance to and the size of adjacent trees. Therefore, in uniformly spaced stands it may be possible to model crown contact damping as a function of stand density index (SDI), a common forestry measure which incorporates both of these variables.     

Hygrophorones A-G: fungicidal cyclopentenones from Hygrophorus species (Basidiomycetes)

Twenty new 5-(hydroxyalkyl)-2-cyclopentenone derivatives (hygrophorones) could be isolated from Hygrophorus latitabundus, H. olivaceoalbus, H. persoonii, and H. pustulatus. Their fungicidal activity was exemplarily tested. The hygrophorones have structural similarities to the antibiotic pentenomycin. Chemically, hygrophorones are 2-cyclopentenones with hydroxy or acetoxy substituents at C-4 and/or C-5. An odd-numbered 1' oxidized alkyl chain (C(11), C(13), C(15), or C(17)) is attached at C-5. In addition, from H. persoonii the new gamma-butyrolactone derivative [5-(E)-2-hydroxytetradexylidene-5H-furan-2-one] could be isolated. Some hygrophorones are responsible for the color reaction of the stipes of these fungi upon treatment with potassium hydroxide solution. Structural elucidations are based on 1D ((1)H, (13)C) and 2D (COSY, NOESY, HSQC, HMBC) NMR spectroscopic analyses as well as HR-FT-ICR-MS investigations.     

Semisystematic nomenclature of brassinosteroids

The assignment of the trivial name to new isolated or detected brassinosteroid is based on the trivial names of seven different brassinosteroids, with names assigned according to the plant source from which they were first isolated. To avoid some observed mistakes in assigning trivial names to these compounds and the impractical constant usage of their systematic names, we propose a semisystematic nomenclature of brassinosteroids, in which (22R,23R)-2,3,22,23-tetrahydroxy-5-campestane, the trivial name of which is 6-deoxocastasterone, is considered the functional parent compound and is named brassinostane or brassinane. A set of rules for naming the remaining natural brassinosteroids is presented.     

Chain-breaking antioxidant activity of natural polyphenols as determined during the chain oxidation of methyl linoleate in Triton X-100 micelles

Natural polyphenols (PP) are known as potent antioxidants, which are believed to prevent many degenerative diseases, including cancer and atherosclerosis. Much attention in the literature has been given to the antioxidant activity of PP-containing products; however, information on the antioxidative properties of individual PP is rather poor and controversial. In this work, the chain-breaking antioxidant activities of several natural PP and their synthetic analogs were determined during the chain oxidation of methyl linoleate in an aqueous buffered, pH 7.40, micellar solution of Triton X-100, induced by 2,2'-azobis(2-amidinopropan) dihydrochloride at 37 degrees C. Use of the mode of the controlled chain reaction allowed separate determination of the rate constant for the reaction of PP with the lipid peroxy radical and the stoichiometric factor of inhibition (f), which shows how many kinetic chains can be terminated by one molecule of PP. All the PP studied display a pronounced antioxidant activity. A significant difference in f value between catechol derivatives and pyrogallol derivatives was found. While with pyrogallol derivatives (gallic acid, epigallocatechin, propyl gallate, myricetin), f was found to be around 2, the theoretically expected value, f, for catechol derivatives (catechol, catechin, epicatechin, quercetin, rutin, caffeic acid) was found to be within the range 3.6-6.3. The elevated antioxidant capacity of catechol derivatives may be explained by the contribution of products of PP oxidative transformation, most likely by dimers, to inhibition. With catechin, epicatechin, and quercetin, the reactivity of products exceeds that of original PP. A real chain-breaking antioxidant activity of PP is likely determined not so much by the reactivity of the original PP as by the probability of the formation of active products and their antioxidant activities. The above findings were applied to explain some features of the antioxidant activity of teas and red wines.     

A peptide mimetic of Gal-alpha 1,3-Gal is able to block human natural antibodies

The carbohydrate of Gal-alpha1,3-Gal is thought to be the major antigenic epitope present on pig vascular endothelium. The peptides that mimic the binding of antigenic epitope (Gal-alpha1,3-Gal) to lectin BS-I-B4 were identified from screening a filamentous phage-displayed random library. A phage bearing the peptide NCVSPYWCEPLAPSARA has been identified to bind the lectin strongly. Melibiose was able to inhibit the binding of the human natural anti-alpha Gal antibody to the peptide competitively. Our experiments show that the peptide mimetic of Gal-alpha1,3-Gal is able to inhibit the agglutination of pig RBCs by human natural antibody or lectin BS-I-B4. The peptide inhibitor of human natural antibodies may prove useful in pig-to-human xenotransplantation.     

Scavenging of reactive oxygen species by a novel glucurinated flavonoid antioxidant isolated and purified from spinach

NAO is a natural water soluble antioxidant that was isolated and purified from spinach leaves. Using HPLC, NMR, and CMR spectroscopy, the main components were identified as flavonoids and p-coumaric acid derivatives. The NAO was found to be a very effective antioxidant in several in vivo and in vitro biological systems. In the present study, the antioxidant activity of the novel antioxidant glucurinated flavonoid (GF) isolated and characterized from NAO, is compared to well-known antioxidants. In addition, the direct free radical scavenging properties of the purified component GF were studied using the electron spin resonance (ESR) technique. GF and NAO were found to be superior to EGCG and NAC and to the Vitamin E homologue Trolox in inhibiting reactive oxygen species (ROS) formation in the autooxidation system of linoleic acid and in fibroblasts exposed to metal oxidation. GF and NAO were found to inhibit the ESR signal intensity of DMPO-O(2) radical formation during the riboflavin photodynamic reaction. 10 mM GF caused approximately 90% inhibition in the intensity of the ESR signal, while NAO at a concentration of 60 microg/ml caused an inhibition of about 50%. Using the Fenton reaction, GF and NAO were found to inhibit DMPO-OH radical formation. A concentration of 2 mM GF caused a 70% inhibition in the intensity of the DMPO-OH radical ESR signal, while propyl gallate at the same concentration caused only 50% inhibition. Furthermore, both GF and NAO also inhibited the (1)O(2) dependent TEMPO radical generated in the photoradiation TPPS4 system. About 80% inhibition was obtained by 4 mM GF. The results obtained indicate that the natural antioxidants derived from spinach may directly affect the scavenging of ROS and, as a consequence, may be considered as effective sources for combating oxidative damage.