Phospholipases are ubiquitous enzymes that hydrolyze phospholipids. Based on the cleavage site of the ester linkage in the substrate phospholipids, phospholipases are classified into four major types, phospholipase A (PLA), phospholipase B (PLB), phospholipase C (PLC), and phospholipase D (PLD), which are further classified into various subtypes. Phospholipases hydrolyze phospholipids into various signaling products including phosphatidic acid (PA), diacylglycerol (DAG), free fatty acids (FFAs), and lyso-phospholipids (LPLs). These signaling products regulate numerous processes such as cytoskeletal dynamics, growth, homeostasis, membrane remodeling, nutrient acquisition, secretion, signal transduction, stress tolerance, sexual development, and virulence in various organisms including fungi. Due to these key cellular roles, phospholipases are also promising targets in diagnostic and therapeutic applications. In this review, we discuss current knowledge about the cellular roles of different classes of phospholipases in fungi.

Multiple cellular roles of Neurospora crassa plc-1, splA2, and cpe-1 in regulation of cytosolic free calcium, carotenoid accumulation, stress responses, and acquisition of thermotolerance § Phospholipase C1 (PLC1), secretory phospholipase A2 (sPLA2) and Ca 2+ /H + exchanger proteins regulate calcium signaling and homeostasis in eukaryotes. In this study, we investigate functions for phospholipase C1 (plc-1), sPLA2 (splA2) and a Ca 2+ /H + exchanger (cpe-1) in the filamentous fungus Neurospora crassa. The Δplc-1, ΔsplA2, and Δcpe-1 mutants exhibited a growth defect on medium supplemented with the divalent ionophore A23187, suggesting that these genes might play a role in regulation of cytosolic free Ca 2+ concentration ([Ca 2+ ]c) in N. crassa. The strains lacking plc-1, splA2, and cpe-1 possessed higher carotenoid content than wild type at 8°C, 22°C, and 30°C, and showed increased ultraviolet (UV)-survival under conditions that induced carotenoid accumulation. Moreover, Δplc-1, ΔsplA2, and Δcpe-1 mutants showed reduced survival rate under hydrogen peroxide-induced oxidative stress and induced thermotolerance after exposure to heat shock temperatures. Thus, this study revealed multiple cellular roles for plc-1, splA2, and cpe-1 genes in regulation of [Ca 2+ ]c, carotenoid accumulation, survival under stress conditions, and acquisition of thermotolerance induced by heat shock.

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We investigated phenotypes of the double mutants of the calcium (Ca) signaling genes plc-1, splA2, and cpe-1 encoding for a phospholipase C1 (PLC-1), a secretory phospholipase A (sPLA), and a Ca/H exchanger (CPE-1), respectively, to understand the cell functions regulated by their genetic interactions. Mutants lacking plc-1 and either splA2 or cpe-1 exhibited numerous defects including reduced colonial growth, stunted aerial hyphae, premature conidiation on plates with delayed germination, inappropriate conidiation in submerged culture, and lesser mycelial pigmentation. Moreover, the ∆plc-1; ∆splA2 and ∆plc-1; ∆cpe-1 double mutants were female-sterile when crossed with wild type as the male parent. In addition, ∆plc-1, ∆splA2, and ∆cpe-1 single mutants displayed higher carotenoid accumulation and an increased level of intracellular reactive oxygen species (ROS). Therefore, the pleiotropic phenotype of the double mutants of plc-1, splA2, and cpe-1 suggested that the genetic interaction of these genes plays a critical role for normal vegetative and sexual development in N. crassa.

Idiopathic intracranial hypertension (IIH) is a condition of unknown etiology and is characterized by elevated intracranial pressure. In this case series we describe the clinical features and responses to treatment of patients presented with IIH. It is a retrospective study of four patients who were presented in our hospital between August 2020 and December 2021 and all patients ethnically belonged to northeast India. The patients were evaluated and diagnosed based on history, physical examination, imaging as well as modied Dandy criteria. Low doses of acetazolamide were recommended for all the patients. Timely diagnosis and accurate treatment of IIH is of utmost importance to avoid any irreversible visual loss.