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  • Author: C.S. Juan, x
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Numerous studies have demonstrated induction of proteins in plant tissues by wounding and infestations by various pests and pathogens. Lipoxygenase (LOX) is among the proteins that has been found to be induced by pathogens, but detailed information on the induction of LOX has not been reported. We have found a large (up to 10-fold) increase in LOX activity upon wounding of soybean (Glycine max L. Merr.) leaves and variable increases due to feeding of the twospotted spider mite. This induction in LOX activity was reflected in increases in amounts of both LOX protein and transcripts suggesting that the induction was at the transcriptional level. LOX activity was also found to be increased in unwounded leaves from plants with wounded leaves lower on the stem indicating that translocatable factors can cause remote induction of LOX activity.

Abstract

The actinobacterium Streptomyces cyaneus CECT 3335 was evaluated for its ability to delignify spruce wood chips (Picea abies) after 2 weeks of incubation prior to refiner mechanical pulping. Weight loss of the chips during the treatment ranged from 2% to 3%. Chemicalanalysis of the treated wood showed an increase in acid-soluble lignin content concomitant with a notable increase in the acid/aldehyde+ketone [AC/(AL+KE)] ratio of the lignin compared with the control. Structural alterations in wood cell walls were observed by optical and scanning microscopy using astra blue-safranin staining and cryosections stained with gold/palladium, respectively. A gradual loss of lignin from the lumen towards the middle lamella and incipient defiberization could be observed. The estimation of specific energy for the defibration and refining stages of treated pulp showed a 24% reduction in the energy required, largely due to a 30% saving in the defibration of chips. The analysis of handsheets obtained from treated pulp showed a notable improvement in some strength properties, such as breaking length, tear index and stretch. In addition, the high Gurley air resistance value indicates more packing of the voids of the fiber network. These results demonstrate for the first time the suitability of Streptomyces cyaneus for biomechanical pulping purposes.

Abstract

The present study describes a new species of Trichodina found in the mucus of the body surface of 137 farmed and wild silver catfish (Rhamdia quelen) located in southern Brazil and in the gills of 99 banded knife fish (Gymnotus sp.) captured in the basin of Pantanal. Smears of the body surface mucus and gills were air dried at room temperature and impregnated with silver nitrate and stained with Giemsa for analysis of the adhesive disc, denticles and macronucleus. Characterized as a medium trichodinid, Trichodina quelenii n. sp. resembles T. heterodentata and T. acuta. It differs from T. heterodentata by the shape of the blade and from T. acuta by the lack of central circle. Furthermore, the distinct shape of the blade of T. quelenii n. sp. differs from all previously described species for the genus, leaving no doubt it is a new species.