Mechanism of mercerization revealed by X-ray diffraction

We studied the crystalline conversion of cellulose fiber from cellulose I to cellulose II (mercerization) by X-ray diffraction, focusing on the putative chain-polarity conversion from parallel to antiparallel. The structural change of Na-cellulose was examined during stepwise changes in NaOH concentration. Either Na-cellulose I or Na-cellulose II was formed depending on the initial NaOH concentration. Once formed, both structures were stable and did not inter-convert to each other when the NaOH concentration was changed. Such stability indicates that the parallel-to-antiparallel conversion is not likely to take place in the crystalline region of Na-cellulose. Regeneration of cellulose II from both forms of alkali cellulose proceeded with the formation of 0.44 nm lattice plane corresponding to the sheet of (1 ¯1 0) plane of cellulose II, showing that the molecular stacking due to van der Waals' interaction is the driving force of the formation of cellulose II. A mechanism was proposed whereby the geometry of the cellulose molecule allows close fitting of the hydrophobic faces only in the antiparallel arrangement, thus driving formation of the antiparallel structure of cellulose II.This study was presented in part at the 47th Annual Meeting of the Japan Wood Research Society, Kochi, April 1997; and at the 6th Annual Meeting of the Cellulose Society of Japan, Tokyo, June 1999     

Widespread translational inhibition by plant miRNAs and siRNAs

High complementarity between plant microRNAs (miRNAs) and their messenger RNA targets is thought to cause silencing, prevalently by endonucleolytic cleavage. We have isolated Arabidopsis mutants defective in miRNA action. Their analysis provides evidence that plant miRNA-guided silencing has a widespread translational inhibitory component that is genetically separable from endonucleolytic cleavage. We further show that the same is true of silencing mediated by small interfering RNA (siRNA) populations. Translational repression is effected in part by the ARGONAUTE proteins AGO1 and AGO10. It also requires the activity of the microtubule-severing enzyme katanin, implicating cytoskeleton dynamics in miRNA action, as recently suggested from animal studies. Also as in animals, the decapping component VARICOSE (VCS)/Ge-1 is required for translational repression by miRNAs, which suggests that the underlying mechanisms in the two kingdoms are related.     

Molecular Responses to Cadmium in Roots of Pisum Sativum L.

Molecular responses to Cd were studied in roots of three pea genotypes (cv. Frisson, VIR4788, VIR7128) growing in a polluted substrate. Root and shoot fresh biomass was decreased by Cd pollution in all genotypes. Gene expression profiling after one weeks' exposure to Cd revealed that genes encoding stress-related proteins (heat-shock protein, pI206, chitinase, chalcone isomerase), a metallothionein, γ -glutamylcysteine synthetase and glutathione reductase were up-regulated in the pea genotypes. A glutathione synthetase gene was activated only in VIR4788 but a homoglutathione synthetase gene was unaffected by Cd, and concomitantly glutathione/homoglutathione accumulation in plant roots did not change with Cd stress. However, the overall concentration of thiol groups, which indicate the presence of phytochelatins and/or homophytochelatins, increased more than 2-fold.     

Species‐specific distribution model may be not enough: The case study of bottlenose dolphin (Tursiops truncatus) habitat distribution in Pelagos Sanctuary

1. Geospatial models are used to predict the distribution of terrestrial and marine species, according to their ecological and ethological habits. The bottlenose dolphin is a cosmopolitan marine top predator, inhabiting most of the ocean, with the exception of polar and subpolar waters. This wide distribution is associated with a remarkable plasticity in ecological and behavioural habits, which makes it difficult to model and predict its distribution.
2. This study proposes a ‘multi‐type approach’ to predict the presence and distribution of the bottlenose dolphin in the Pelagos Sanctuary, a Specially Protected Area of Mediterranean Importance located in the north‐west Mediterranean Sea. A multi‐type model based on random forest regression was developed, analysing the distribution habits of two geographical units living in the Pelagos area.
3. When compared with a classical single‐type model, the multi‐type model performed much better in a prediction test (true skill statistics, TSS = 85% vs. 52%), confirming the value of this experimental approach. This work suggests that wild species should not be considered as one single‐type entity, as local specialization may change and shape their distribution habits.

     

Anti-inflammatory, antioxidant and antifungal furanosesquiterpenoids isolated from Commiphora erythraea (Ehrenb.) Engl. resin

The topical anti-inflammatory, free radical scavenging and antifungal activities of essential oils and extracts of Commiphora erythraea (Ehrenb.) Engl. resin were investigated. The hexane extract significantly inhibited oedema when applied topically in Croton oil-induced ear oedema assay in mice. The same extract showed antioxidant activity in DPPH radical scavenging assay. A bioguided separation of the hexane extract led to the isolation of furanosesquiterpenoids 1 and 2 that showed a weak antifungal activity, while compounds 3-5 resulted to be antioxidant (EC₅₀ 4.28, 2.56 and 1.08 mg/mL, respectively) and anti-inflammatory (30, 26 and 32% oedema reduction, respectively).     

Partition of Nonylphenol and Related Compounds Among Different Aquatic Compartments in Tiber River (Central Italy)

Nonylphenol (NP), nonylphenol mono- and di-ethoxylate (NP1EO, NP2EO) and bisphenol A (BPA) were determined in water, suspended particulate matter (s.p.m.) and bed sediment collected from the most polluted stretch of Tiber river (Italy) in the neighbourhood of Rome. Analytes were recovered from water samples by solid-phase extraction (SPE) on Si–C₁₈ cartridges and analysed by HPLC with fluorescence detection. Solid samples were extracted by using an aqueous solution of the non-ionic surfactant Tween 80. Results indicated that 2–42% of NP, 9–45% of NP1EO, 11–18% of NP2EO and 4–62% of BPA respectively occurred in the suspended phase. In general, for all compounds a higher affinity for s.p.m. than for bed sediments was observed, reflecting differences in the nature of particles and in their sorption capacity for organic micro-pollutants. The partition of target compounds in river compartments was affected by differences in hydrological conditions between the two sampling campaigns. Run-off from the basin or resuspension/redissolution from sediments was an important source of nonylphenol and bisphenol A during high discharge regimes. Partition coefficients of compounds (log K _oc ) between water and s.p.m. were calculated under stable flow condition. K _oc values, experimentally measured in the river, were higher than those predicted by K _ow , implying that specific chemical interaction could occur in the sorption mechanisms for these group of compounds.     

Hepatocyte nuclear factor 4 alpha is associated with mesenchymal-epithelial transition in developing kidneys of C57BL/6 mice

During kidney development, the metanephric mesenchyme (MM) develops into the nephron through mesenchymal-epithelial transition (MET). We have previously reported that knock-down of the expression of hepatocyte nuclear factor 4 alpha (Hnf4a) gene induces failure of cellular organization in the condensed mesenchyme (CM) of cultured embryonic kidneys. To elucidate the details of MET during nephrogenesis, embryonic mouse kidneys were analyzed by electron microscopy, immunohistochemistry, and molecular biology. The findings showed that the intercellular junction, but not the basal lamina, was present in the CM. Additionally, immediately after Hnf4a gene expression, the expression of epithelial genes (Krt8, Tjp1, and Cdh1) increased, and those of mesenchymal genes (Acta1 and Vim) decreased, in the CM compared to the MM. To clarify the relationship between MET and Hnf4α, the fibroblast cell line with forced expression of Hnf4α protein were analyzed. In this model, it was noted that Hnf4α induced increasing epithelial and decreasing mesenchymal gene expression. In these, up-regulation of Pvrl1, -2, and Mllt4 genes which mediate the formation of apico-basal polarity, were found. These results, and those of previous findings, indicate that Hnf4α protein is associated with the initiation of MET in early nephrogenesis.     

Acute myeloid leukemia with mastocytic and megakaryocytic differentiation in a calf

A diagnosis of acute myeloid leukemia was made in a 10-month-old Holstein female calf. The leukemia was macroscopically characterized by great enlargement of the spleen and moderate enlargement of some lymph nodes. Histochemical and immunohistochemical examination disclosed the presence of neoplastic cells either containing metachromatic and tryptase-positive granules or expressing factor VIII-related antigen. The granules, which were positive for naphthol AS-D chloroacetate esterase and did not have particulate contents, were distinct from those of basophilic leukemia cells. This leukemia was thought to be derived from a common myeloid progenitor capable of giving rise to megakaryocyte-erythrocyte progenitors and granulocyte-monocyte progenitors with the ability to differentiate into mast cells.