Current Perspectives on Uniparental Mitochondrial Inheritance in Cryptococcus neoformans

Abstract

The mitochondrion is a vital organelle in most eukaryotic cells. It contains its own DNA which differs from nuclear DNA, since it is often inherited from only one parent during sexual reproduction. In anisogamous mammals, this is largely due to the fact that the oocyte has over 1000 times more copies of mitochondrial DNA than the sperm. However, in the isogamous fungus Cryptococcus neoformans, uniparental mitochondrial inheritance (UMI) still occurs during sexual reproduction. It is proposed that UMI might have evolved in the last common ancestor of eukaryotes. Thus, understanding the fundamental process of UMI in lower eukaryotes may give insights into how the process might have evolved in eukaryotic ancestors. In this review, we discuss the current knowledge regarding the cellular features as well as the molecular underpinnings of UMI in Cryptococcus during the mating process, and open questions that need to be answered to solve the mystery of UMI in this eukaryotic microbe.

Ergosterol Is Critical for Sporogenesis in Cryptococcus neoformans

“…Hyphal extension can occur indefinitely until unknown stimuli cause the aerial hyphal tip to swell and become a basidium. Here, the two parental nuclei fuse, undergoing meiosis and repeated rounds of mitosis to give rise to four haploid spore chains that bud off the surface of the basidium (Figure 1A) [4,10,17]. C in the dark for two weeks.…”

Insights into Fungal Mitochondrial Genomes and Inheritance Based on Current Findings from Yeast-like Fungi

“…A zygote is formed after cell fusion through the conjugation tube. Meanwhile, the UPI of the mitochondrial genome is strictly controlled, and the mitochondrial genome of hypha germinating from the zygote was determined to come from the MATa parent only (Figure 2) [91,92]. A transcription factor Mat2, which is not encoded by the mating type locus, is activated in MATa cells and is involved in mitochondrial preservation [91,92].…”

“…Meanwhile, the UPI of the mitochondrial genome is strictly controlled, and the mitochondrial genome of hypha germinating from the zygote was determined to come from the MATa parent only (Figure 2) [91,92]. A transcription factor Mat2, which is not encoded by the mating type locus, is activated in MATa cells and is involved in mitochondrial preservation [91,92]. Thus, overexpression of Mat2 in the MATα strain leads to BPI of the mitochondrial genome while mating with the MATa strain in C. neoformans [93].…”

“…(D) In C. neoformans, Six2a/Six1α and Mat2 drive the degradation of mitochondrial nucleoids and structures that are from α mating type cells to maintain the UPI of mitochondria. This figure is reproduced from the references of [9,78,88,91,95].…”

On the History and Applications of Congenic Strains in Cryptococcus Research

“…So far, the evidence suggests that mitochondrial DNA inheritance is controlled by multiple genetic loci, and that differences in their interaction with the mating type locus could be an important source of variation. Detailed discussion on this topic can be found in a separate chapter by Matha and Lin in this Special Issue [56].…”