In soybean seedlings, Cd2+ affected growth and inhibited photosynthesis. Both the length and fresh mass decreased more in roots than in shoots. Cd2+ stress caused an increase in ratio of chlorophyll (Chl) (a+b)/b by 1.3 fold and ratio of total xanthophylls/β-carotene by 3 fold compared to the control. A reduced activity of photosystem 2 by about 85 % measured in Cd2+-treated chloroplasts was associated with a dramatic quenching of fluorescence emission intensity, with a band shift of 4 nm. A major suppression of absorption was accompanied with shift in peaks in the visible region of the spectrum. In Cd2+-treated chloroplasts a selective decline in linolenic acid (18:3), the most unsaturated fatty acid of chloroplasts, paralleled with the ten fold enhancement in ethylene production. A three fold increase in peroxidase activity was found in chloroplasts treated with Cd2+ compared to the control . Addition of 1 mM glutathione (GSH) counteracted all the retardation effects in soybean seedling growth induced by Cd2+. Thus GSH may control the Cd2+ growth inhibition as it detoxifies Cd2+ by reducing its concentration in the cytoplasm and removing hydrogen peroxide generated in chloroplasts.
While investigating the parasites of several marine fishes from the Western Atlantic, the Southern Gulf of Mexico and Central America (Panama), the following monogenoidean species from the gills of gerreid fishes (Gerreidae) were found: Diplectanum gatunense sp. n. (Diplectanidae) and Octouncuhaptor eugerrei gen. et sp. n. (Dactylogyridae) in Eugerres brasilianus (Cuvier) from Gatun Lake in the Panama Canal Watershed, and Diplectanum mexicanum sp. n. in Diapterus rhombeus (Cuvier) from the coast of Campeche State, Mexico. New diplectanid species are distinguished from other species of the genus by the general morphology of the copulatory complex and by the shape of the anchors and bars on the haptor. Octouncuhaptor gen. n. is proposed for its new species having slightly overlapping gonads (testis posterodorsal to the ovary), a dextrolateral vaginal aperture, a copulatory complex consisting of a coiled male copulatory organ with counterclockwise rings with the base articulated to the accessory piece, 8 pairs of hooks and the absence of anchors and bars on haptor. Our analysis of morphological features of Diplectanum species on gerreids evidences that these parasites more closely resemble each other than the known species from sciaenids suggesting that split between gerreids and sciaenids resulted in parasite speciation.
In this work, the injuries caused by clethodim herbicide application as well as the use of exogenous salicylic acid (SA) as a protective agent against clethodim in Zea mays leaves were examined. Although the target for clethodim is the inhibition of acetyl coenzyme A carboxylase (ACCase) which is the key enzyme for fatty acid biosynthesis, it can indirectly affect the photosynthetic machinery, gaseous exchange and some biochemical parameters. Clethodim application caused chlorosis and yellowing of leaf-tip parts. Higher doses caused browning or reddening of leaves and sometimes dead parts of the leaf margins were observed. The rate of photosynthesis was significantly lowered and the pigments content was highly reduced as a response to clethodim spraying. Moreover, other gas-exchange properties were altered. Furthermore, accumulation of high amounts of carbohydrates, proteins and proline were detected. SA spraying three days prior clethodim application caused partially or totally disappearance of clethodim injuries and kept the leaves similar to those of control. Improved photosynthesis and enhanced pigments content were observed in leaves treated with SA. Other analyzed parameters showed values similar to those of the corresponding control. From the experimental work, an evidenced role of SA working against clethodim effects was suggested and discussed in this paper., D. E. M. Radwan, D. M. Soltan., and Obsahuje bibliografii