Phloem translocation of Fe,Cu, Mn,and Zn in Ricinus seedlings in relation to the concentrations of nicotianamine,an endogenous chelator of divalent metal ions,in different seedling parts

During the first 8 days of germination the Ricinus seedling is supplied with all nutrients by the endosperm via phloem transport. In 4- to 8-days-old seedlings the concentrations and contents of Fe, Cu, Mn and Zn, and nicotianamine (NA) in the endosperm, cotyledons, hypocotyl and roots were estimated. From the data obtained translocation rates and flow profiles for the metals were established. The main sink for Fe, Mn and Zn were the cotyledons whereas Cu was mainly imported into the hypocotyl. Maximum flow rates occurred between days 5 and 7, for Zn between days 6 and 8.The time kinetics of NA and divalent metal ion concentrations and contents are interpreted as co-transport. The role of NA as transport vehicle of micronutrients in the sieve tubes is discussed.     

Effects of scale on detecting interactions between Coleophora and Eriocrania leaf-miners

Abstract.

• 1 The possibility of interactions between leaf-miners in the genus Eriocrania and Coleophora serratella L. on birch (Betula pendula Ehrh. and B.pubescens Roth.) was studied via: (i) co-occurrence patterns on random samples of leaves; (ii) palatability of Eriocraniidae-mined leaves to C.serratella, in laboratory and field preference tests.
• 2 In the field, C.serratella and Eriocrania spp. fed on common leaves less frequently than expected by chance. This result is consistent with, and could be explained by, the avoidance of mined leaves shown by C.serratella in most of the feeding trials.
• 3 Avoidance was not observed at the between-tree level, i.e. the number of leaves mined by each type of insect was unrelated. However, when tree species was taken into account, an inverse distribution was observed: mine abundance was higher for Eriocrania spp. on B.pubescens, whereas for C.serratella it was higher on B.pendula.
• 4 B.pubescens leaves mined by Eriocrania spp. had consistently higher phenolic contents and were better at precipitating proteins than unmined leaves. These induced chemical changes could explain the reduced preference shown by C.serrate1la for Eriocrania mined leaves.
• 5 We speculate about the evolution of adult host-plant selection shown by these insects in response to potential larval interactions.

     

Human T Cell Leukemia Virus Type 1 (HTLV-1) Antibodies in Healthy Populations and Renal Transplanted Patients in the North-East of Brazil

The seroprevalence of human T cell leukemia virus type 1 (HTLV-1) infection was investigated in Brazilians (570): native inhabitants (298) and descendants from Japanese (272) living in Recife and its neighborhoods—North-east of Brazil. Furthermore, polytransfused renal transplanted patients (54) were also examined for the serological status to this virus. The seropositivity to HTLV-1, screened by enzyme-linked immunosorbent assay (ELISA), was low: 1.34% for the local population and 0.73% for the descendants from Japanese. However, the seropositivity for the renal transplanted patients was found to be 11.1%. This higher value suggests that this retrovirus infection seems to be of importance in this clinical condition.     

马铃薯实生苗子叶及下胚轴原生质体培养研究

用马铃薯普通栽培种（Ｓｏｌａｎｕｍ ｔｕｂｅｒｏｓｕｍ Ｌ．）３ 个品系的实生苗刚展开的子叶及下胚轴游离和培养原生质体。实验结果表明,子叶及下胚轴原生质体的分裂频率显著地高于经多次继代繁殖的试管苗顶部幼嫩叶片和茎尖的原生质体;在强连续光照下培养的实生苗,其原生质体的产量和质量都显著地高于弱光下培养的;在完全黑暗下培养的黄化实生苗不能游离出完整的原生质体;酶解前对子叶及下胚轴切段在酶液中进行真空渗透处理能显著地提高原生质体的产量,但此种处理对试管苗叶片无明显效果;下胚轴原生质体的产量显著地高于子叶,但在原生质体的质量方面,这两种组织间无明显的差异     

Effects of aluminium on growth and cation uptake in seedlings of Eucalyptus mannifera and Pinus radiata

This experiment was designed to examine the effects of aluminium (Al) on the growth of Pinus radiata (D. Don) and Eucalyptus mannifera subsp. mannifera (Mudie) seedlings in culture solutions in a glasshouse to help explain the failure of radiata pine trees on some acid, low fertility soils in Australia on which the native eucalypts flourish. Aluminium (Al) in culture solution increased the growth of roots and shoots of seedlings of both species but while growth of the eucalypt continued to increase with increases in Al to 2.222 μM, growth of the pine was largest at 370 μM Al. In addition to total root length, specific root length (length per unit dry weight), a measure of fineness of the root, increased in the eucalypt seedlings as the substrate Al increased. Growth of the shoots and roots of the pine in the absence of any added Al was extremely poor suggesting that Al, in low concentrations, may be an essential element or ameliorate some other factors in solution culture at low pH. Root and shoot concentrations of K increased with increasing Al, whilst Ca and Mg Concentrations decreased and Mn concentrations were unaffected in both species. Tissue Ca and Mg concentrations were 2 to 3 times higher in the eucalypt seedlings than the pine at all levels of added Al due to greater uptake of these elements by the eucalypt. In contrast, at the highest concentration of Al in the medium, shoot Al concentrations were lower in the cucalypt than in the pine due to a greater proportion of Al being retained in the eucalypt roots. These differences between the seedlings in terms of root growth and tissue cation concentrations may help explain the ability of eucalypt species to maintain vigorous growth on acid soils high in Al and low in Ca and P, where growth of the pines failed.     

Bayesian analysis of linkage between genetic markers and quantitative trait loci. I. Prior knowledge

Summary Prior information on gene effects at individual quantitative trait loci (QTL) and on recombination rates between marker loci and QTL is derived. The prior distribution of QTL gene effects is assumed to be exponential with major effects less likely than minor ones. The prior probability of linkage between a marker and another single locus is a function of the number and length of chromosomes, and of the map function relating recombination rate to genetic distance among loci. The prior probability of linkage between a marker locus and a quantitative trait depends additionally on the number of detectable QTL, which may be determined from total additive genetic variance and minimum detectable QTL effect. The use of this prior information should improve linkage tests and estimates of QTL effects.     

Response of small birch plants (Betula pendula Roth.) to elevated CO2 and nitrogen supply

Small birch plants were grown for up to 80 d in a climate chamber at varied relative addition rates of nitrogen in culture solution, and at ambient (350 μmol mol^-1) or elevated (700 μmol mol^-1) concentrations of CO₂. The relative addition rate of nitrogen controlled relative growth rate accurately and independently of CO₂ concentration at sub-optimum levels. During free access to nutrients, relative growth rate was higher at elevated CO₂. Higher values of relative growth rate and net assimilation rate were associated with higher values of plant N-concentration. At all N-supply rates, elevated CO₂ resulted in higher values of net assimilation rate, whereas leaf weight ratio was independent of CO₂. Specific leaf area (and leaf area ratio) was less at higher CO₂ and at lower rates of N-supply. Lower values of specific leaf area were partly because of starch accumulation. Nitrogen productivity (growth rate per unit plant nitrogen) was higher at elevated CO₂. At sub-optimal N-supply, the higher net assimilation rate at elevated CO₂ was offset by a lower leaf area ratio. Carbon dioxide did not affect root/shoot ratio, but a higher fraction of plant dry weight was found in roots at lower N-supply. In the treatment with lowest N-supply, five times as much root length was produced per amount of plant nitrogen in comparison with optimum plants. The specific fine root length at all N-supplies was greater at elevated CO₂. These responses of the root system to lower N-supply and elevated CO₂ may have a considerable bearing on the acquisition of nutrients in depleted soils at elevated CO₂. The advantage of maintaining steady-state nutrition in small plants while investigating the effects of elevated CO₂ on growth is emphasized.     

Organic matter and nutrient cycling within an endemic birch stand in the Etna massif (Sicily):Betula aetnensis Rafin

At altitudes between 1300 m to 2100 m in the Etna massif (Sicily), an endemic species of theBetula genus,Betula aetnensis Rafin, grows in a well-defined microclimatical context. Aboveground biomass and nutrient content studies within one stand revealed no significant differences from the otherBetula species, normally found in colder more temperate climate regions.Throughout the studied sites, biomass production, nutrient cycling and various structural or physiological characteristics (leaf area index) varied very little.Other researches indicate that the originality ofBetula aetnensis lies more in the histological or anatomical characteristics of its water conducting system which enables the species to adapt to Mediterranean-climate summer droughts in the Etna massif.

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Riassunto Sull'Etna, tra 1300 e 2100 m d'altitudine, in una zona microclimaticamente ben definita del versante nordorientale, si rinviene laBetula aetnensis Rafin.Dallo studio della fitomassa e della mineralomassa aerea del bosco di Monte Baracca, è emerso che non vi sono differenze notevoli con le altre specie indagate del genereBetula, più caratteristiche dei climi temperati e freddi.La produzione di biomassa, cosi come la gestione degli elementi nutritivi, è molto simile ai diversi popolamenti già indagati, cosi come certe caratteistiche strutturali e fisiologiche (leaf area index).L'originalità dellaBetula aetnensis è da ricercarsi nel vantaggio che ne ricava, a livello endogeno, sfruttando le caratteristiche istologiche ed anatomiche del suo apparato conduttore, che le consentono un efficace ed eccellente adattamento alle condizioni di siccità estive particolari del clima mediterraneo del vulcano.

     

The Role of Cellular and Extracellular Matrix Adhesion Proteins in Organ Transplantation

The specific adhesion of cells to other cells or to particular tissue microenvirorvments is a basic function of cell migration and recognition, and underlines many biologic processes including embryogenesis, repair and immunity. Leukocytes express an array of surface receptors broadly known as “accessory adhesion molecules.” which mediate most cell -cell interactions, direct lymphocyte traffic between anatomical compartments, and facilitate cellular adhesion to the inflammation or alloantigenic sites (Springer 1990). In addition, adhesion molecules are involved in the process of antigen recognition, and may costimulate cell activation and transformation. These proteins are thought to affect the very early antigen independent events between host leukocytes and vascular endothelium. Because of these activities, the subject of adhesion molecules is gaining interest in the field of organ transplantation, in both conceptualization and development of novel therapeutic strategies (de Sousa et al. 1991, Kupiec-Weglinski et al. 1993a, Heemann et al. 1993).