Growth, Differentiation and Sexuality

2 Organelle Inheritance in Yeasts and Other Fungi
L.J. García-Rodríguez 1 ,A.C.Gay 1 , L.A. Pon 1
CONTENTS
I. Introduction ......................... 21
II. Cytoskeletal Organization and Function
in Organelle Movement and Inheritance .... 22
A. Organization of the Actin Cytoskeleton
inFungi .......................... 22
B. Organization of the Microtubule
CytoskeletoninFungi ............... 23
III. Nuclear Migration in Fungi .............. 24
A. Control of Nuclear Position
During Interphase in S. pombe ......... 24
B. NuclearMigrationinHyphae.......... 24
IV. Organelle-Specific Inheritance
in Fungi ............................. 25
A. Mitochondria...................... 25
B. EndoplasmicReticulum.............. 28
C. Vacuoles,theLysosomesofYeast....... 29
D. TheGolgiApparatus ................ 30
E. Peroxisomes....................... 31
V. Conclusions .......................... 32
References ........................... 32
I. Introduction
Internal compartmentalization is a hallmark of the
eukaryotic cell. The evolution from prokaryote to
eukaryote resulted in the physical separation of the
genome from the cytoplasm, and the development
of dynamic subcellular compartments that coordinate
their functions and abundance according
to the needs of the cell. Organelles create order
within a cell, prevent undesirable interactions between
the various cellular components, and perform
specialized functions. While each organelle
has a defined cellular role, their localization, copy
number, size, and morphology can vary. For instance,
variations in the carbon source for growth
of budding yeast can impact peroxisomal biosynthesis
and result in a tenfold change in the abundance
of mitochondria (Pon and Schatz 1991; Einerhand
et al. 1992).
1 Department of Anatomy and Cell Biology, Columbia University,
College of Physicians and Surgeons, New York, NY 10032, USA
Studies of organelle inheritance have focused
primarily on the nucleus. Nuclear inheritance,
which uses the mitotic spindle to segregate
nuclei and chromosomes, occurs by a conserved
and tightly regulated mechanism. The inheritance
of other organelles, on the other hand,
occurs by more diverse and less well-understood
mechanisms. Organelles like mitochondria and
chloroplasts cannot be produced de novo. This
is true, in part, because they contain DNA,
which must undergo template-dependent replication.
As a result, these organelles must be
transferred from mother to daughter cells to
ensure normal daughter cell viability and/or
function, and more than one mechanism for
these essential inheritance events has been
identified.
On the other hand, since the endoplasmic
reticulum is continuous with the outer nuclear
envelope, Golgi and lysosomes (vacuoles) can,
in principle, be produced de novo from ER
that is inherited with the nucleus. Interestingly,
even in cases where cellular control of organelle
inheritance is not obligatory, mechanisms for
inheritance have been identified. Thus, the high
cost of de novo organelle synthesis may have driven
the development of mechanisms for organelle
inheritance even when they are not required.
The use of modern microscopy techniques,
such as time-lapse fluorescence imaging, in
combination with genetic and molecular biology
approaches, has led to a rapid expansion of
our understanding of organelle distribution and
inheritance. Fungi, and yeasts in particular, have
been used as model systems for these combinedapproach
studies of organelle inheritance. Thus,
this chapter describes organelle distribution and
inheritance in yeasts and other fungi. Specifically,
we focus on the mechanisms underlying
organelle abundance in dividing cells, in addition
to a brief consideration of nuclear migration in
non-dividing cells.
The Mycota I
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© Springer-Verlag Berlin Heidelberg 2006