The use of tropical forest (Agroecosystems and wild plant harvesting) as a source of food in the bribri and cabecar cultures in the Caribbean Coast of Costa Rica

For the Bribri and the Cabecar Indians of Costa Rica the environment is divided in two: the “near”, indigenous space; and the “far”, natural space, which they think does not belong to them. In the former, the following agroecosystems can be distinguished according to biodiversity and intensity of human activity: tropical home garden, rotating slashand-burn agriculture, plantain polyculture, and plantain monoculture. In the “far” space, these two culturally close groups harvest wild plants observing ancestral rules, which have helped ensure a sustainable use of forest resources. Their diet is based on 84 species, of which 24 are harvested in the “far” environment (hombron, semko, platanillo, tacaco, etc.) and 60 are obtained in the “near” environment (maize, bean, cacao, manioc, etc.). Owing to acculturation, exotic species (mainly rice, sugarcane, plantain, cacao and citrus fruit) have become part of their diet and crops.     

Chloride absorption in salt-sensitive Carrizo citrange and salt-tolerant Cleopatra mandarin citrus rootstocks is linked to water use

In this work, seedlings of two citrus rootstocks, the salt-tolerant Cleopatra mandarin (Citrus reshni Hort. ex Tan.) and the salt-sensitive Carrizo citrange (Citrus sinensis [L.] Osb. x Poncirus trifoliata [L.] Raf.) were used to study the relationship between chloride and water uptake. The results indicated that net chloride uptake rates in both genotypes were alike and decreased linearly with the time of salinity exposure, although they were more rapidly reduced in the tolerant genotype. In each rootstock, chloride uptake rates paralleled the decreases in transpiration rates. When transpiration was modified, concomitant changes in leaf Cl(-) concentrations were observed. There was a high positive correlation between total chloride content per plant and total water absorbed. In addition, the data indicate that the tolerant genotype "excluded" more chloride, i.e. it absorbed lower amounts of chloride per volume of water. Cleopatra also possessed a less efficient root system for water uptake and a higher shoot-to-root ratio. The results show that, overall, chloride absorption is linked to water use and that further tolerance in Cleopatra is mostly conferred by superior root resistance to Cl(-) uptake. Therefore, it is proposed that chloride absorption and, hence, salt tolerance in citrus depends to a great extent upon water use.     

Uptake of water and solutes through twigs of Picea abies (L.) Karst

Summary Uptake of water and magnesium chloride solution was investigated through the outer surface of twigs of Picea abies (L.) Karst. Water uptake was determined by using pressure/volume (P/V) curves of the twigs as a basis for calculation to avoid problems of superficial extraneous water. When water was sprayed on bark and needles of 3- to 7-year-old twigs at a xylem water potential of -1.00 MPa, they absorbed as much as 80 mm³ water in 200 min/g twig dry weight as the twig water potential recovered to -0.15 MPa. With fluorescent dyes, pathways for absorption of water and solutes through the twig bark were found, particularly through the radially orientated ray tissue. In addition to uptake by mass flow, magnesium could also diffuse along a concentration gradient from the twig surface into the xylem. In the field, the magnitude of these uptake processes would depend on the concentration of elements deposited by atmospheric precipitation, the concentration gradient between the plant surface and the xylem sap, the xylem water potential and the intensity and duration of each precipitation event.     

Uptake of Proteins by Plant Roots

The patterns of uptake of fluorescein-labelled lysozyme (Fl-lysozyme) by barley, maize, onion, tomato and vetch are similar as revealed by fluorescence microscopy. Penetration of the root cap and through the epidermis into the cortex increases with time of exposure and decreases with higher salt concentrations. In fact, one molar ethylammonium chloride can remove most of the absorbed protein from treated roots and the space observed to be stained by Fl-lysozyme in this manner can be visualized as “free space”. Results with sterile and non-sterile barley roots were indistinguishable. At low ionic strength, Fl-lysozyme can penetrate cells and complex with nucleoli. Such cell protoplasts appear “coagulated”. Uptake results with fluorescein per se were unlike those with protein. The uptake of a much larger molecule, ferritin, is confined to the epidermis and root cell walls. Localized, absorbed protein and root growth inhibition by basic proteins have yet to be related.     

A Preliminary Study on the Wood Anatomy of Manglietia aromatica Dandy [

The present paper deals mainly with the wood structures of “Paramanglietia aromatica” Hu & Cheng and Paramichelia (Pierre) Hu of the Magnoliaceae. These wood structures are listed in Table Ⅰ. In comparison of their wood anatomical features with relsted genera[4], we find that (Ⅰ) the wood anatomy of the reduced genus “Para- manglietia” Hu et Cheng is still within the range of Manglietia Dandy and that (2 the wood anatomical features of Paramichelia (Pierre) Hu is very similar to those of Michelia L. and Tsoongiodendron Chun. We also find that the wood anatomy of Manylietia aromatica Dandy [“Parawanglietia aromatica” (Dandy) Hu & Cheng] is less similar to Manglietiastrum Law (see Table 1).     

Heterogeneity of binding sites of proflavin on DNA

The desorption and melting with temperature of proflavine–DNA complexes has been studied by spectrophotometry and spectrofluorometry. Two methods are described to determine at each temperature the concentration of free and bound dye. The first one is based on the quenching of fluorescence of the free dye by the iodine ion, the second on fluorescence polarization measurements. It is shown that the sites where the bound dye fluoresces are thermally less stable than those where it is quenched, in such a way that a redistribution of the dye between the two types of sites occurs at intermediate temperatures, leading to a drop in the total fluorescence. This confirms the nature of the “emitting” sites which correspond to AT-rich region, while “quenched” sites correspond to GC-rich region. The first have a larger binding constant at room temperature, but only the latter are stabilized by dye intercalation. The desorption and melting have also been followed through the relative changes of absorption. The curves obtained at different wavelengths are not superimposed which is at variance with what is observed with complexes of proflavine with poly dAT and poly dG.dC. The beginning of the desorption process corresponds to minor variations at 445 nm, the maximum of absorption of the free dye, but large changes occur at 460 nm, the maximum of the difference spectrum of the complexes proflavine–poly dAT and proflavine-poly dG.dC. The spreading of the melting curves for different wave lengths must therefore reflect the dependence of the absorption spectra of the dye on the nature of the neighboring bases. However, the action spectrum of the fluorescence, which gives the absorption spectrum of the “emitting” sites only, is identical with the total absorption spectrum of the bound dye.     

Characteristics of the Uptake Mechanism of Chloride Ions in Excised Roots of a Woody Plant (Citrus)

The characteristics of the uptake mechanism of chloride ions in citrus (Citrus spp.) were studied in excised, high-salt, roots as to the nature of the isotherm at a wide range of uptake durations and Cl^? concentrations. In addition, the effects of metabolic inhibitors, low temperature and various treatments were studied, and compared with Cl^? uptake in excised roots of wheat (Triticum vlgare) under the same conditions. It was found that the uptake mechanism in excised roots of citrus differs considerably from that in wheat: (1) the rate of active uptake from 10 mM NaCl in citrus is 2.0 to 4.3 umol Cl^? per g dry weight and h (vs. 35.5 umol in wheat); (2) there is no saturation of the system even at high external concentrations (up to 90 mM), and uptake is continuous; (3) uptake in citrus is less sensitive to KCN and dinitro-phenol. In addition, it was noted that the age of citrus seedlings and the initial chloride content of both citrus and wheat roots markedly affected Cl^? uptake. The data were analyzed in the light of the dual mechanism hypothesis of ion uptake, and it was concluded that only system 2 (high Km), is operating in the excised citrus roots studied. This is in accordance with the conditions prevailing in the field (whence the plant material was collected): high concentration of the soil solution in contact with the roots, and high salt status of the tissue. It is further suggested that the uptake of ions in citrus (and presumably in other perennial woody plants), is related to its growth habits and to the size and morphology of the root systems.     

Diospyros melanoxylon,a bread-winner tree of India

This endemic plant of India and Ceylon is used in various ways. Besides being the source of Indian ebony, its wood is also utilized for making boxes, combs, ploughs and beams. The fruits are eaten and sold commercially. The bark is burnt by tribals to “cure” small-pox. The seeds are prescribed as cure for mental disorders, palpitation of heart and nervous breakdown. Above all, the leaves of this plant constitute one of the most important raw materials of the “Bidi” (Indian cheap smoke) industry.     

A Cytomorphological Study on the Anther Opening of Foxtail Millet and Wheat

A concept of “open space” in the anther tissue structure of foxtail millet (Setaria italica) and wheat (Triticurn aestivum) has been suggested. In the late stage of anther development, “open spaces” are formed beneath the epidermis at the opening place between two anther chambers. They get through the bilateral edge of the anther longitudinally making the chambers easy to open. “Open space” is considered to be one of the inner factors of anther opening in foxtail millet and wheat.     

Morphological factors determining salt tolerance in citrus seedlings: the shoot to root ratio modulates passive root uptake of chloride ions and their accumulation in leaves

The results presented in this work were obtained with two citrus genotypes, the chloride-tolerant Cleopatra mandarin (Citrus reshni Hort. ex Tan.) and the chloride-sensitive Carrizo citrange [Citrus sinensis (L.) Osb. × Poncirus trifoliata (L.) Raf.]. The data show that chloride uptake under salinization is driven by passive forces. In both species, net rates of chloride root uptake increased linearly, without saturation, with the increase of external NaCl concentrations (30–240 mol m^–3). Uptake rates, on a μ g g root dry weight^–1 h^–1 basis, in Cleopatra and Carrizo decreased (from 38 to 21) and increased (from 21 to 35), respectively, with the increase (about three-fold) of the shoot to root ratio. With the appropriate shoot to root ratio in each genotype, it was demonstrated that at identical external doses of NaCl, Cl^– uptake rates and Cl^– xylem concentrations in the two species were very similar. Root pruning and defoliation showed that the amount of chloride taken by the plant was a function of the size of the root system, whereas leaf chloride concentration, the parameter responsible for salt damage, was dependent upon leaf biomass. Measurements of water transpiration suggested that chloride root uptake and leaf accumulation might be linked to water absorption and transpiration rates, respectively. The data indicate that plant morphology is a crucial factor determining salt-tolerance in citrus.     

The Uptake of 2-Deoxy-dGlucose by Isolated Ricinus Cotyledons

The uptake of the non-metabolizable glucose analogue, 2-deoxy-d -glucose (DOG) has been followed in isolated cotyledons of Ricinus communis L. Within 2 min of immersion in a labelled DOG medium, DOG phosphate (DOG-P) was detectable in the tissue. DOG uptake was relatively rapid for 30 min after which it slowed down but nevertheless continued for many hours; DOG was eventually accumulated against a concentration gradient. Internal DOG-P concentration also rose for the first 30 min, but then reached a plateau. The relationship between uptake and external concentration was close to linear during the first hour, and subsequently curvilinear. Analysis of “wash-out” curves indicated that after very rapid exit from the surface and free space of the tissue, the half-time for exit of the remaining 85% of the absorbed DOG was approximately 250 min. By comparison, the half-time for exit of sorbitol was 30 min. No DOG-P could be detected in the wash-out solutions. When cotyledons were transferred to labelled medium after preloading in non-labelled DOG, the specific activity of the internal DOG pool rose faster than that of the DOG-P. Both curves flattened out when their specific activity was less than half that of the external medium. Addition of d -glucose to the medium depressed DOG-P formation, but only when the incubation period was less than 45 min. Arguments are presented for concluding (a) that DOG uptake is mediated by a specific uptake mechanism; (b) that more than one internal DOG pool is involved; and (c) that the observed phosphorylation is not a necessary step in the entry process into either of the pools, whether the latter are in series or in parallel.     

Seasonal Variation of Nitrogenous Compounds in Components of the Kiwifruit Vine

Free amino acids in 6-year-old kiwifruit vines [Actinidia deliciosa(A. Chev.) C. F. Liang et A. R. Ferguson] were measured overthe course of 1 year using components obtained from whole-vineharvests. Tissues examined from the perennial structure consistedof the wood and cortex of structural roots, wood and bark ofstem, leader and 1-year-old fruiting canes. Free acids in theannual growth (fine roots, flowers, fruit, leaves and non-fruitingshoots) were also measured. The range of amino acids extracted indicated that kiwifruitconforms to a conventional pattern of nitrogen metabolism. Acidspresent in greatest concentration depended on tissue type andsampling time. In perennial components and fine roots, arginineand glutamine were the predominant species, followed by gamma-aminobutyrate,aspartate, glutamate, alanine and valine. Generally, maximumconcentrations of all free acids were measured in a 10-weekperiod around budbreak. These same acids, plus asparagine, serineand threonine, were also prevalent in annual growth. In leaves,flowers and non-fruiting shoots, concentrations were greatestin the young tissue and declined with age. By contrast, concentrationsof arginine, asparagine and glutamine in fruit peaked approximately10 weeks after anthesis, subsequent to the cell division phaseof growth. During the year, free arginine averaged 44, 48 and 58 % of thetotal N in the fine roots, and the cortex and wood of structuralroots, respectively (the quantity of total N and amino-N inother components of the structural framework was much less thanthat in root tissue). Arginine was the principal N-containingspecies measured in xylem sap vacuum-extracted from 1-year-oldcanes over winter. During the period of vegetative growth, however,glutamine and nitrate were the principal N-transport forms present.The study highlights the importance of the fine root systemas the primary location of nitrogenous reserves in this plantand identifies arginine as the dominant N-storage form. Actinidia deliciosa (A. Chev.) C. F. Liang et A. R. Ferguson, amino acid composition, kiwifruit, nitrogen, whole-plant harvesting     

Progress in scaffold‐free bioprinting for cardiovascular medicine

Biofabrication of tissue analogues is aspiring to become a disruptive technology capable to solve standing biomedical problems, from generation of improved tissue models for drug testing to alleviation of the shortage of organs for transplantation. Arguably, the most powerful tool of this revolution is bioprinting, understood as the assembling of cells with biomaterials in three‐dimensional structures. It is less appreciated, however, that bioprinting is not a uniform methodology, but comprises a variety of approaches. These can be broadly classified in two categories, based on the use or not of supporting biomaterials (known as “scaffolds,” usually printable hydrogels also called “bioinks”). Importantly, several limitations of scaffold‐dependent bioprinting can be avoided by the “scaffold‐free” methods. In this overview, we comparatively present these approaches and highlight the rapidly evolving scaffold‐free bioprinting, as applied to cardiovascular tissue engineering.     

土壤可溶性有机氮研究进展

可溶性有机氮(SON)和无机氮是陆地生态系统氮循环过程中重要的氮素形态,互为“源”和“汇”。陆地生态系统中氮素和其他营养元素的矿化、固持、淋溶和植物吸收均与SON有密切的联系。SON在土壤物质循环和养分流动等动态过程中的作用越来越受到关注,已成为生态学、环境学、土壤学、水文学等研究领域的热点之一。本文综述了国内外对土壤SON的研究进展,包括SON的定义和测定、SON库容大小和组成、植物和微生物对SON的吸收利用、SON来源及其影响因素、SON在土壤中的转化运移和淋失等。综合国内外研究结果发现,土壤SON是一个复杂的多组分可溶性有机物的混合物,主要为难降解的物质(惰性成分),能快速矿化分解的物质(活性成分)占比较低。由于惰性成分和活性成分在周转速率上的差异,SON在生态系统氮循环中的地位不能完全通过SON的容量特征来反映。因此,为了更准确地反映SON在氮周转、氮吸收和氮流失中的作用,未来需要创新研究方法并对SON组分加以区分:研究SON在氮转化和氮吸收中的作用时,重点关注SON中的活性成分;研究SON在氮淋溶径流损失中的贡献时,则重点关注SON中的惰性成分。     

Heavy Metal Uptake by Willow Clones from Sewage Sludge-Treated Soil: The Potential for Phytoremediation

Willow (Salix spp.) has shown potential for use in the phytoremediation of soil contaminated with heavy metals. In particular, it can be grown in short rotation coppice systems to produce biomass that can be used for energy production. Twenty different species or varieties of willow, grown over 2 years (1995 to 1997) on a soil that was highly contaminated with heavy metals due to long-term sewage sludge disposal, showed considerable variation in survival, biomass production and metal uptake. The willows could be divided into two groups after the first harvest. One group had relatively low Ni and Cu in the bark and high Cd and Zn in the wood, with a good survival rate and biomass production. This group partitioned Cu, Cd, and Zn into the wood tissue from the bark, whereas Ni was excluded. The second group had relatively high Ni and Cu in the bark and low Cd and Zn in the wood and performed poorly in terms of survival and biomass production. Of the 20 types of willow used, 11 showed potential for use in phytoremediation, combining good survival and biomass production with high metal uptake. Of the others, 2 failed to survive until the second harvest and the other 7 had very poor survival rates.     

Kinos of Eucalyptus species and their acid degradation products

The kinos of Eucalyptus astringens, E. lehmannii and E. platypus contain mainly polymerized leucocyanidin, appreciable amounts of dihydrokaempferol 3-rhamnoside and trace amounts of other components, The acid degradation products of different kinos contained components not present in the products from wood and bark. These include phloroglucinol and two other components whose properties are described.     

Fatty acids,resin acids and phenols in Pinus muricata

Acetone-soluble extractives of “blue” and “green” strain Pinus muricata D. Don were found to consist of free and “combined” fatty acids, resin acids, and phenols. The composition of the extractives from the two strains was similar though “green” strain P. muricata contained more Δ^8(9),15 isopimaric acid than “blue” strain. This difference may be used to identify these muricata strains if the age of the wood precludes a monoterpene examination.     

Gibberellin like Substances in Parts of Developing Barley Grain

In husks, the activity of gibberellin-like substances extracted with aqueous methanol (M-“free” GAs) showed a maximum on the 9th day after pollination. In developing embryos, M-“free” GAs showed no biological activity, whereas biological active component(s) were obtained when the embryos were extracted with Tris buffer. The “free” GAs found in the buffer homogenates (B-“free” GAs) of developing embryos showed a maximum of activity on the 33rd day after pollination. Bound GAs recovered from the precipitated protein of the buffer homogenate (“Protein-bound” GAs) were found in embryo and endosperm. Developing endosperm generally contains the major amount of the extractable gibberellin-like substances. In this tissue, the amount of all examined fractions (M-“free” GAs, B-“free” GAs and “protein-bound” GAs) increased after pollination to reach a maximum on the 21st day, before decreasing to a minimum at grain maturity. Moreover, the curves for dry weight increase and gibberellin like substances follow a remarkably similar course, with the latter reaching its maximim slightly earlier than the former one. This result indicates that gibberellines may participate in the regulation of the accumulation process in the endosperm of barley grain.     

Inhibition of [3H]dopamine and [3H]serotonin uptake by cocaine: comparison between chopped tissue slices and synaptosomes.

Cocaine inhibits both [3H]dopamine and [3H]serotonin uptake in rat striatum and nucleus accumbens. In a chopped tissue slice preparation, the inhibition curve for [3H]dopamine uptake is biphasic, suggesting two components of uptake, whereas the curve for [3H]serotonin uptake is steep and apparently monophasic. In synaptosomal preparations, both curves are monophasic. Monensin, a sodium ionophore, inhibits uptake but does not change the shape of the cocaine inhibition curve in synaptosomes, suggesting that the biphasic inhibition curves in slices are not likely due to differential sodium gradients across the slices. In tissue slices, only the component which is more sensitive to inhibition by cocaine and related drugs is inhibitable by nicotine. This suggests that the two components of dopamine uptake in tissue slices may be differentially regulated.     

Gibberellin-like Substances in Developing Barley Grain and Their Relation to Dry Weight Increase

Gibberellin-like activity of two varieties of barley (Hordeum vulgare L.) at different stages of grain development was determined by barley endosperm bioassay (acid phosphatase bioassay). Activity of the acidic ethyl-acetate fraction (“free” GAs) in both varieties displayed two maxima, a first maximum at the 9th day and a second one 20 to 21 days after pollination. Activity of the n-butanol fraction (“bound” GAs) first dropped to a minimum level at the 9th day, then increased to reach a maximum 32 days after pollination, and finally decreased again towards maturity. From the 9th day after pollination, a conversion of “free” GAs to “bound” GAs has probably occurred. From the 12th day after pollination, the curves of rate of dry weight increase and of “free” GAs run nearly parallel, but the latter reached its maximum about 2–4 days earlier than the former. The results indicate that gibberellins may participate in the regulation of the accumulation processes into the barley grain.