Iron rescues glucose-mediated photosynthesis repression during lipid accumulation in the green alga Chromochloris zofingiensis.

Energy status and nutrients regulate photosynthetic protein expression. The unicellular green alga Chromochloris zofingiensis switches off photosynthesis in the presence of exogenous glucose (+Glc) in a process that depends on hexokinase (HXK1). Here, we show that this response requires that cells lack sufficient iron (-Fe). Cells grown in -Fe+Glc accumulate triacylglycerol (TAG) while losing photosynthesis and thylakoid membranes. However, cells with an iron supplement (+Fe+Glc) maintain photosynthesis and thylakoids while still accumulating TAG. Proteomic analysis shows that known photosynthetic proteins are most depleted in heterotrophy, alongside hundreds of uncharacterized, conserved proteins. Photosynthesis repression is associated with enzyme and transporter regulation that redirects iron resources to (a) respiratory instead of photosynthetic complexes and (b) a ferredoxin-dependent desaturase pathway supporting TAG accumulation rather than thylakoid lipid synthesis. Combining insights from diverse organisms from green algae to vascular plants, we show how iron and trophic constraints on metabolism aid gene discovery for photosynthesis and biofuel production.

Case report: Utilization of a scleral lens to mitigate exposure keratopathy and associated mental health decline.

PURPOSE: To report a case of acute exposure keratopathy with comorbid depression and improvement of both conditions with the use of a scleral lens (SL). OBSERVATIONS: A 72-year-old male with a past ocular history significant for extensive basal cell carcinoma (BCC) excision of the right upper and lower eyelids presented for evaluation of exposure keratitis and consideration of a SL for the right eye. Examination was notable for post-surgical irregular lid margins with lagophthalmos, trichiasis and an Oxford Grade I staining of the central exposed cornea. Medical history was notable for chronic severe depression and anxiety with suicidal ideation. Upon treatment with a SL, the patient noted ocular comfort, and reported significantly improved affect. CONCLUSION AND IMPORTANCE: Currently, there is no peer reviewed literature reporting on the management of exposure keratopathy in the setting of comorbid affective disorders. This case highlights the improvement in quality of life for a patient with exposure keratitis and severe depression with suicidal ideation and points to the potential utilization of a SL to mitigate the risk of mental health decompensation.