Trophic status of Chlamydomonas reinhardtii influences the impact of iron deficiency on photosynthesis

To investigate the impact of iron deficiency on bioenergetic pathways in Chlamydomonas, we compared growth rates, iron content, and photosynthetic parameters systematically in acetate versus CO2-grown cells. Acetate-grown cells have, predictably (2-fold) greater abundance of respiration components but also, counter-intuitively, more chlorophyll on a per cell basis. We found that phototrophic cells are less impacted by iron deficiency and this correlates with their higher iron content on a per cell basis, suggesting a greater capacity/ability for iron assimilation in this metabolic state. Phototrophic cells maintain both photosynthetic and respiratory function and their associated Fe-containing proteins in conditions where heterotrophic cells lose photosynthetic capacity and have reduced oxygen evolution activity. Maintenance of NPQ capacity might contribute to protection of the photosynthetic apparatus in iron-limited phototrophic cells. Acetate-grown iron-limited cells maintain high growth rates by suppressing photosynthesis but increasing instead respiration. These cells are also able to maintain a reduced plastoquinone pool

Artemisia spp. essential oils against the disease-carrying blowfly Calliphora vomitoria

Background: Synanthropic flies play a considerable role in the transmission of pathogenic and non-pathogenic microorganisms. In this work, the essential oil (EO) of two aromatic plants, Artemisia annua and A. dracunculus, were evaluated for their abilities to control the blowfly Calliphora vomitoria. A. annua and A. dracunculus EOs were extracted, analysed and tested in laboratory bioassays. Besides, the physiology of EOs toxicity and the EOs antibacterial and antifungal properties were evaluated. Results: Both Artemisia EOs were able to deter C. vomitoria oviposition on fresh beef meat. At 0.05 μL cm-2 A. dracunculus EO completely inhibited C. vomitoria oviposition. Toxicity tests, by contact, showed LD50 of 0.49 and 0.79 μL EO per fly for A. dracunculus and A. annua, respectively. By fumigation, LC50 values were 49.54 and 88.09 μL L-1 air for A. dracunculus and A. annua, respectively. EOs AChE inhibition in C. vomitoria (IC50 = 202.6 and 472.4 mg L-1, respectively for A. dracunculus and A. annua) indicated that insect neural sites are targeted by the EOs toxicity. Finally, the antibacterial and antifungal activities of the two Artemisia EOs may assist in the reduction of transmission of microbial infections/contaminations. Conclusions: Results suggest that Artemisia EOs could be of use in the control of C. vomitoria, a common vector of pathogenic microorganisms and agent of human and animal cutaneous myiasis. The prevention of pathogenic and parasitic infections is a priority for human and animal health. The Artemisia EOs could represent an eco-friendly, low-cost alternative to synthetic repellents and insecticides to fight synanthropic disease-carrying blowflies

Organic acids metabolism in roots of grapevine rootstocks under severe iron deficiency

Background and aims In many important viticultural areas of the Mediterranean basin, plants often face prolonged periods of scarce iron (Fe) availability in the soil.The objective of the present work was to perform a comparative analysis of physiological and biochemical responses of Vitis genotypes tosevere Fe deficiency. Methods Three grapevine rootstocks differing in susceptibility to Fe chlorosis were grown with and without Fe in the nutrient solution. Results Rootstock 101-14, susceptible to Fe chlorosis, responded to severe Fe deficiency by reducing the root activity of phosphoenolpyruvate carboxylase (PEPC) and malate dehydrogenase(MDH),however,itaccumulated high levels of citric acid. By contrast, rootstock 110 Richter, tolerant to Fe chlorosis, maintained an activemetabolismoforganicacids,butcitricacidaccumulationwaslowerthanin101-14.Similarlyto101-14, rootstock SO4 showed a strong decrease in PEPC and MDH activities. Nevertheless it maintained moderate citric acid levels in the roots, mimicking the response by 110 Richter. Conclusions Root PEPC and MDH activities can be used as tools for screening Fe chlorosis tolerance. Conversely, organic acids accumulation in roots may not be a reliable indicator of Fe chlorosis tolerance, particularly under conditions of severe Fe deficiency, because of their probable exudation by roots.Our results show that drawing sound conclusions from screening programs involving Fe deficiency tolerance requires short as well as long-term assessment of responses to Fe deprivation