Uptake of ferrous iron histidinate, a promoter of lipid peroxidation, by Ehrlich ascites tumor cells

The kinetics of the uptake of Fe(II)-histidinate, a known promoter of lipid peroxidation, into Ehrlich ascites tumor (EAT) cells and the intracellular binding of iron were studied in vitro. EAT cells (27.10(6)/ml) were incubated in Hanks' balanced salts solution at 37 degrees C for various time intervals in the presence of FeSO4 (1 mM) and L-histidine (10 mM). Total iron was determined by the 1,10-phenanthroline/ascorbate method and ferric iron by reaction with 5-sulfosalicylic acid; the difference was ascribed to ferrous iron. Total iron decreased rapidly in the medium (242 nmol within the first 10 min), and a corresponding increase of total iron (saturation value 376 nmol after 60 min) was determined within the cells, after the cellular proteins had been solubilized with 6 M urea. In the absence of EAT cells, Fe(II)-histidinate was readily oxidized to Fe(III)-histidinate by oxygen, but this reaction was strongly retarded by the tumor cells. The uptake of iron histidinate occurred in the oxidized state, while an uptake of ferrous iron could not be proven unambiguously. When EAT cells were saturated with iron, it was found that 93% of intracellular iron was bound to water-insoluble proteins and 7% was associated with soluble proteins, while no unbound iron was detectable by the method used. It was concluded that, despite the high uptake of total iron, only a very small portion of the intracellular iron was available as a redox catalyst for lipid peroxidation.     

Carbon tetrachloride-induced inhibition of hepatocyte lipoprotein secretion: functional impairment of Golgi apparatus in the early phases of such injury

Functional change of liver Golgi apparatus during carbon tetrachloride (CCl4) poisoning was demonstrated both in rat isolated hepatocytes and in the whole animal. The "in vitro" experimental model provided evidence of Golgi derangement early after giving the haloalkane. The "in vivo" analyses also showed that such an alteration involves both formative and secretory sides of the subcellular structure.     

chs-4, a class IV chitin synthase gene fromNeurospora crassa

InSaccharomyces cerevisiae, most of the cellular chitin is produced by chitin synthase III, which requires the product encoded by theCSD2/CAL1/DIT101/KT12 gene. We have identified, isolated and structurally characterized aCSD2/CAL1/DIT101/KT12 homologue in the filamentous ascomyceteNeurospora crassa and have used a reverse genetics approach to determine its role in vivo. The yeast gene was used as a heterologous probe for the isolation of aN. crassa gene (designatedchs-4) encoding a polypeptide belonging to a class of chitin synthases which we have designated class IV. The predicted polypeptide encoded by this gene is highly similar to those ofS. cerevisiae andCandida albicans. N. crassa strains in whichchs-4 had been inactivated by the Repeat-Induced Point mutation (RIP) process grew and developed in a normal manner under standard growth conditions. However, when grown in the presence of sorbose (a carbon source which induces morphological changes accompanied by elevated chitin content), chitin levels in thechs-4 ^RIP strain were significantly lower than those observed in the wild type. We suggest that CHS4 may serve as an auxiliary enzyme inN. crassa and that, in contrast to yeasts, it is possible that filamentous fungi may have more than one class IV chitin synthase.A. Beth Din and C. A. Specht contributed equally to this work     

Tropical dry woodland loss occurs disproportionately in areas of highest conservation value

Tropical and subtropical dry woodlands are rich in biodiversity and carbon. Yet, many of these woodlands are under high deforestation pressure and remain weakly protected. Here, we assessed how deforestation dynamics relate to areas of woodland protection and to conservation priorities across the world's tropical dry woodlands. Specifically, we characterized different types of deforestation frontier from 2000 to 2020 and compared them to protected areas (PAs), Indigenous Peoples' lands and conservation areas for biodiversity, carbon and water. We found that global conservation priorities were always overrepresented in tropical dry woodlands compared to the rest of the globe (between 4% and 96% more than expected, depending on the type of conservation priority). Moreover, about 41% of all dry woodlands were characterized as deforestation frontiers, and these frontiers have been falling disproportionately in areas with important regional (i.e. tropical dry woodland) conservation assets. While deforestation frontiers were identified within all tropical dry woodland classes of woodland protection, they were lower than the average within protected areas coinciding with Indigenous Peoples' lands (23%), and within other PAs (28%). However, within PAs, deforestation frontiers have also been disproportionately affecting regional conservation assets. Many emerging deforestation frontiers were identified outside but close to PAs, highlighting a growing threat that the conserved areas of dry woodland will become isolated. Understanding how deforestation frontiers coincide with major types of current woodland protection can help target context-specific conservation policies and interventions to tropical dry woodland conservation assets (e.g. PAs in which deforestation is rampant require stronger enforcement, inactive deforestation frontiers could benefit from restoration). Our analyses also identify recurring patterns that can be used to test the transferability of governance approaches and promote learning across social–ecological contexts.