A proposed role for copper ions in cell wall loosening

The measurement of N₂ fixation by legumes is necessary for gaining an understanding of their contributions to the N economies of agricultural and forestry systems and for their management in those systems. We report research to determine whether N₂ fixation of four of the commonly-grown ureide-producing legumes, soybean (Glycine max), cowpea (Vigna unguiculata), mungbean (V. radiata) and black gram (V. mungo), could be quantified from a single sampling and N-solute analysis of xylem sap. Data were derived from a previously-published experiment involving six genotypes of soybean at five field sites and from a second, irrigated experiment in which two genotypes of soybean, and one each of cowpea, mungbean and black gram were assessed in low- and high-nitrate soils for nodulation, yields of shoot and grain dry matter and N, and N₂ fixation using xylem solute (ureide) and ¹⁵N methods. Regression analysis of the published soybean data set indicated that the early pod-fill (R3.5 and R4) samplings for xylem sap gave estimates of percentage of plant N derived from N₂ fixation (%Ndfa) which agreed well with %Ndfa for the entire growing season obtained from ¹⁵N analysis of the shoots at R6-7. There was a marginal benefit in combining the R3.5 and R4 samplings and using the average of the two, with regression coefficients (r ²) increasing from 0.86 (R3.5 or R4 alone) to 0.92 (average of R3.5+R4). There was no additional benefit in combining R3, R3.5 and R4. In the second experiment, agreement between ¹⁵N-determined %Ndfa and either measured (R4 sampling) or calculated ureide-determined %Ndfa (R3.5 sampling) was also good (r ² of 0.73 (R4) and 0.79 (R3.5)). We conclude that seasonal %Ndfa can be accurately estimated using the xylem solute (ureide) method from a single sampling of xylem sap during early pod-fill (R3.5) and that this simplification of the protocol of the technique may encourage expanded use.     

Plant regeneration from protoplasts of Enteromorpha intestinalis (Chlorophyta, Ulvophyceae) as seedstock for macroagal culture

A continuous micropropagation was established from protoplasts of thegreen alga Enteromorpha intestinalis. The effects of two differentcrude enzymes and the osmolarity at different concentrations of the enzymesolution on algal protoplast yields were tested. The optimal enzymecomposition for cell wall digestion and protoplast viability was 2%cellulase R 10 Onozuka and 2% Aplysie with 0.5 m mannitol. Largenumbers of Enteromorpha protoplasts were released (10.0 × 10⁶protoplasts from 1 g fresh thalli) and settled on a rangeof substrata. Regeneration of the protoplasts followed the normal patternfor this species. Conditions for pure cultures and efficient systems offloating supports with nets were determined to optimise the product qualityof plantlets of Enteromorpha. A promising storage process has beendeveloped which involves including protoplasts in beads of alginic acid gel.Plants regenerated from protoplasts may also be used as seedstock tofacilitate propagation for macroalgal culture.     

Detection of quantitative trait loci for growth and fatness in pigs

A quantitative trait locus (QTL) analysis of growth and fatness data from a three-generation experimental cross between Meishan (MS) and Large White (LW) pig breeds is presented. Six boars and 23 F1 sows, the progeny of six LW boars and six MS sows, produced 530 F2 males and 573 F2 females. Nine growth traits, i.e. body weight at birth and at 3, 10, 13, 17 and 22 weeks of age, average daily gain from birth to 3 weeks, from 3 to 10 weeks and from 10 to 22 weeks of age, as well as backfat thickness at 13, 17 and 22 weeks of age and at 40 and 60 kg live weight were analysed. Animals were typed for a total of 137 markers covering the entire porcine genome. Analyses were performed using two interval mapping methods: a line-cross (LC) regression method where founder lines were assumed to be fixed for different QTL alleles and a half-/full-sib (HFS) maximum likelihood method where allele substitution effects were estimated within each half-/full-sib family. Both methods revealed highly significant gene effects for growth on chromosomes 1, 4 and 7 and for backfat thickness on chromosomes 1, 4, 5, 7 and X, and significant gene effects on chromosome 6 for growth and backfat thickness. Suggestive QTLs were also revealed by both methods on chromosomes 2 and 3 for growth and 2 for backfat thickness. Significant gene effects were detected for growth on chromosomes 11, 13, 14, 16 and 18 and for backfat thickness on chromosome 8, 10, 13 and 14. LW alleles were associated with high growth rate and low backfat thickness, except for those of chromosome 7 and to a lesser extent early-growth alleles on chromosomes 1 and 2 and backfat thickness alleles on chromosome 6.     

Complex regulation of nucleoside transporter expression in epithelial and immune system cells

Nucleoside transporters have a variety of functions in the cell, such as the provision of substrates for nucleic acid synthesis and the modulation of purine receptors by determining agonist availability. They also transport a wide range of nucleoside-derived antiviral and anticancer drugs. Most mammalian cells coexpress several nucleoside transporter isoforms at the plasma membrane, which are differentially regulated. This paper reviews studies on nucleoside transporter regulation, which has been extensively characterized in the laboratory in several model systems: the hepatocyte, an epithelial cell type, and immune system cells, in particular B cells, which are non-polarized and highly specialized. The hepatocyte co-expresses at least two Na+-dependent nucleoside transporters, CNT1 and CNT2, which are up-regulated during cell proliferation but may undergo selective loss in certain experimental models of hepatocarcinomas. This feature is consistent with evidence that CNT expression also depends on the differentiation status of the hepatocyte. Moreover, substrate availability also modulates CNT expression in epithelial cells, as reported for hepatocytes and jejunum epithelia from rats fed nucleotide-deprived diets. In human B cell lines, CNT and ENT transporters are co-expressed but differentially regulated after B cell activation triggered by cytokines or phorbol esters, as described for murine bone marrow macrophages induced either to activate or to proliferate. The complex regulation of the expression and activity of nucleoside transporters hints at their relevance in cell physiology.     

Differentiation of Human Umbilical Cord Matrix Mesenchymal Stem Cells into Neural-Like Progenitor Cells and Maturation into an Oligodendroglial-Like Lineage

Mesenchymal stem cells (MSCs) are viewed as safe, readily available and promising adult stem cells, which are currently used in several clinical trials. Additionally, their soluble-factor secretion and multi-lineage differentiation capacities place MSCs in the forefront of stem cell types with expected near-future clinical applications. In the present work MSCs were isolated from the umbilical cord matrix (Wharton''s jelly) of human umbilical cord samples. The cells were thoroughly characterized and confirmed as bona-fide MSCs, presenting in vitro low generation time, high proliferative and colony-forming unit-fibroblast (CFU-F) capacity, typical MSC immunophenotype and osteogenic, chondrogenic and adipogenic differentiation capacity. The cells were additionally subjected to an oligodendroglial-oriented step-wise differentiation protocol in order to test their neural- and oligodendroglial-like differentiation capacity. The results confirmed the neural-like plasticity of MSCs, and suggested that the cells presented an oligodendroglial-like phenotype throughout the differentiation protocol, in several aspects sharing characteristics common to those of bona-fide oligodendrocyte precursor cells and differentiated oligodendrocytes.     

Anatomical and physiological changes of in vitro-propagated Vriesea imperialis (Bromeliaceae) in the function of sucrose and ventilated containers

Abstract

Under in vitro culture conditions, plants may present physiological and anatomical disorders, which can interfere negatively after ex vitro transfer. The aim of this investigation was to analyze the impacts of natural ventilation and sucrose supply on the anatomy and physiology of Vriesea imperialis. Plants previously grown in vitro were transferred to culture medium containing 0, 15, 30 or 45?g L^?1 sucrose. Three different culture container sealing systems were tested: lids with a green filter (81.35 gas exchanges per day), yellow filter (13.09 gas exchanges per day) or lids with a yellow filter covered with three layers of transparent polyvinylchloride (PVC) film (blocking fluent gas exchange). Sucrose concentrations influenced thickness, lignin and suberin deposition of exodermis cell wall. The modifications verified in leaves, such as higher density of stomata and trichome scales, showed that sucrose can induce osmotic stress in the plants. Photomixotrophic conditions, using containers with intermediate rate of gas exchange (yellow filter) and with 15–30?g L^?1 sucrose, produced an improvement in the growth traits and did not induce anatomical and physiological disturbances.