Download Sager JJ, Bai Q, Burton EA

Review
Linking genes to brain, behavior and neurological
diseases: what can we learn from zebrafish?
S. Guo
How our brain is wired and subsequently generates
functional output, ranging from sensing and locomotion
to emotion, decision-making and learning and memory,
remains poorly understood. Dys-regulation of these processes
can lead to neurodegenerative, as well as neuropsychiatric,
disorders. Molecular genetic together with
behavioral analyses in model organisms identify genes
involved in the formation of neuronal circuits, the execution
of behavior and mechanisms involved in neuropathogenesis.
In this review I will discuss the current
progress and future potential for study in a newly established
vertebrate model organism for genetics, the zebrafish
Danio rerio. Where available, schemes and results
of genetic screens will be reviewed concerning the sensory,
motor and neuromodulatory monoamine systems.
Genetic analyses in zebrafish have the potential to provide
important insights into the relationship between
genes, neuronal circuits and behavior in normal as well
as diseased states.
PENTYLENETETRAZOLE INDUCED CHANGES IN ZEBRAFISH
BEHAVIOR, NEURAL ACTIVITY AND C-FOS EXPRESSION]
S. C. BARABAN,a* M. R. TAYLOR,a P. A. CASTRO,a AND
H. BAIERb
Abstract—Rodent seizure models have significantly contributed
to our basic understanding of epilepsy. However, medically
intractable forms of epilepsy persist and the fundamental
mechanisms underlying this disease remain unclear. Here
we show that seizures can be elicited in a simple vertebrate
system e.g. zebrafish larvae (Danio rerio). Exposure to a
common convulsant agent (pentylenetetrazole, PTZ) induced
a stereotyped and concentration-dependent sequence of behavioral
changes culminating in clonus-like convulsions. Extracellular
recordings from fish optic tectum revealed ictal
and interictal-like electrographic discharges after application
of PTZ, which could be blocked by tetrodotoxin or glutamate
receptor antagonists. Epileptiform discharges were suppressed
by commonly used antiepileptic drugs, valproate
and diazepam, in a concentration-dependent manner. Upregulation
of c-fos expression was also observed in CNS
structures of zebrafish exposed to PTZ. Taken together,
these results demonstrate that chemically-induced seizures
in zebrafish exhibit behavioral, electrographic, and molecular
changes that would be expected from a rodent seizure model.
Therefore, zebrafish larvae represent a powerful new system
to study the underlying basis of seizure generation, epilepsy
and epileptogenesis.
FishNet: an online database of zebrafish anatomy
Robert J Bryson-Richardson*1, Silke Berger1, Thomas F Schilling2,
Thomas E Hall1, Nicholas J Cole1, Abigail J Gibson1, James Sharpe3 and
Peter D Currie*1,4,5
Abstract
Background: Over the last two decades, zebrafish have been established as a genetically
versatile
model system for investigating many different aspects of vertebrate developmental biology.
With
the credentials of zebrafish as a developmental model now well recognized, the emerging
new
opportunity is the wider application of zebrafish biology to aspects of human disease
modelling.
This rapidly increasing use of zebrafish as a model for human disease has necessarily
generated
interest in the anatomy of later developmental phases such as the larval, juvenile, and adult
stages,
during which many of the key aspects of organ morphogenesis and maturation take place.
Anatomical resources and references that encompass these stages are non-existent in
zebrafish and
there is therefore an urgent need to understand how different organ systems and anatomical
structures develop throughout the life of the fish.
Results: To overcome this deficit we have utilized the technique of optical projection
tomography
to produce three-dimensional (3D) models of larval fish. In order to view and display these
models
we have created FishNet http://www.fishnet.org.au, an interactive reference of zebrafish
anatomy
spanning the range of zebrafish development from 24 h until adulthood.
Conclusion: FishNet contains more than 36 000 images of larval zebrafish, with more than 1
500
of these being annotated. The 3D models can be manipulated on screen or virtually
sectioned. This
resource represents the first complete embryo to adult atlas for any species in 3D.
http://books.google.com.br/books?hl=ptBR&lr=&id=Qw6KqLjwtZQC&oi=fnd&pg=PA189&dq=zebrafish+as+a+model+for+studying+g
enetic+aspects+of+epilepsy&ots=Dd1W_wDOPb&sig=ijO0spDlj9Q992rmHAE7ceFqWSw#v
=onepage&q&f=false (Modeling epilepsy and seizures in developing zebrafish larvae) (nao
foi possivel copiar e colar o texto, disponivel no site) Scott Baraban
Letter
Zebrafish, Killifish, Neither Fish, Both Fish?
Glenn S. Gerhard
Weis Center for Research
Danville, Pennsylvania
Renae L. Malek
The Institute for Genomic Research
Rockville, Maryland
Evan Keller
Jill Murtha
Departments of Urology and Pathology
University of Michigan
Ann Arbor
Keith C. Cheng
Jake Gittlen Cancer Research Institute
Department of Pathology
Pennsylvania State College of Medicine
Hershey
In their recent report (1), Herrera and Jagadeeswaran offer
data supporting the use of killifish (annual fish) species over
zebrafish as a genetic model for aging. We write to
emphasize that, despite the limitations that killifish may
circumvent, the zebrafish holds great promise as a model for
aging research (2). In gerontology, as well as in other fields,
a variety of model systems are used to a collective
advantage. For each system, its inevitable disadvantages
do not invalidate the exploitation of its advantages. For
example, despite the inability to develop cancer, important
cancer-related research continues to be conducted in yeast
(3). Similarly, Caenorhabditis elegans is widely used in
gerontology despite the lack of cell division potential in
somatic cells of adults. No model is perfect, and based upon
its numerous experimental advantages and its track record,
the zebrafish should receive serious consideration in any
area of biology.
THE ZEBRAFISH AS A MODEL FOR HUMAN DISEASE
William T. Penberthy, Ebrahim Shafizadeh, and Shuo Lin
1. ABSTRACT
Much of our current understanding of the
function of genes modulating the normal process of
embryonic development has come from mutant analysis.
The availability of thousands of mutant lines in zebrafish
that allows for identification of novel genes regulating
various aspects of embryogenesis has been instrumental in
establishing zebrafish as a robust and reliable genetic
system. With the advances in genomic sequencing, the
construction of several genetic maps, and cloning of
hundreds of ESTs, positional cloning experiments in
zebrafish have become more approachable. An increasing
number of mutant genes have been cloned. Several
zebrafish mutants are representative of known forms of
human genetic diseases. The success of morpholino
antisense technology in zebrafish potentially opens the door
for modeling nearly any inherited developmental defect.
This review highlights the strengths and limitations of
using the zebrafish as an organism for elucidation of the
genetic etiology of human disease. Additionally a survey
of current and future zebrafish models of human disease is
presented.
Spontaneous Seizures and Altered Gene Expression in GABA Signaling Pathways in a mind
bomb Mutant Zebrafish
Hortopan GA, Dinday MT, Baraban SC.
Abstract
Disruption of E3 ubiquitin ligase activity in immature zebrafish mind bomb mutants leads to a
failure in Notch signaling, excessive numbers of neurons, and depletion of neural progenitor
cells. This neurogenic phenotype is associated with defects in neural patterning and brain
development. Because developmental brain abnormalities are recognized as an important
feature of childhood neurological disorders such as epilepsy and autism, we determined
whether zebrafish mutants with grossly abnormal brain structure exhibit spontaneous
electrical activity that resembles the long-duration, high-amplitude multispike discharges
reported in immature zebrafish exposed to convulsant drugs. Electrophysiological recordings
from agar immobilized mind bomb mutants at 3 d postfertilization confirmed the occurrence
of electrographic seizure activity; seizure-like behaviors were also noted during locomotion
video tracking of freely behaving mutants. To identify genes differentially expressed in the
mind bomb mutant and provide insight into molecular pathways that may mediate these
epileptic phenotypes, a transcriptome analysis was
performed using microarray. Interesting candidate genes were further analyzed using
conventional reverse transcriptase-PCR and real-time quantitative PCR, as well as wholemount in situ hybridization. Approximately 150 genes, some implicated in development,
transcription, cell metabolism, and signal transduction, are differentially regulated, including
downregulation of several genes necessary for GABA-mediated signaling. These findings
identify a collection of gene transcripts that may be responsible for the abnormal electrical
discharge and epileptic activities observed in a mind bomb zebrafish mutant. This work may
have important implications for neurological and neurodevelopmental disorders associated
with mutations in ubiquitin ligase activity.
A large-scale mutagenesis screen to identify seizure-resistant zebrafish.
Baraban SC, Dinday MT, Castro PA, Chege S, Guyenet S, Taylor MR
Summary: Purpose: Zebrafish are a vertebrate organism ideally
suited to mutagenesis screening strategies. Although a genetic
basis for seizure susceptibility and epilepsy is well established,
no efforts have been made to study seizure resistance.
Here we describe a novel strategy to isolate seizure-resistant
zebrafish mutants from a large-scale mutagenesis screen.
Methods: Seizures were induced with pentylenetetrazole
(PTZ). Zebrafish were analyzed between 3 and 7 days postfertilization
(dpf). Genome mutations were induced in founders by using
N-ethyl-nitrosourea (ENU). Seizure behavior was monitored
by using a high-speed camera and quantified by locomotiontracking
software. Electrographic activity was monitored by using
a field-recording electrode placed in the optic tectum of agarimmobilized
zebrafish.
Results: Short-term PTZ exposure elicited a burst-suppression
seizure pattern in 3-dpf zebrafish and more complex activity
consisting of interictal- and ictal-like discharges at 7 dpf. Prolonged
exposure to PTZ induced status epilepticus–like seizure
activity and fatality in wild-type zebrafish larvae. With a PTZ
survival assay at 6–7 dpf, we identified six zebrafish mutants
in a forward-genetic screen covering nearly 2,000 F2 families.
One mutant (s334) also was shown to exhibit reduced behavioral
activity on short-term PTZ exposure and an inability to generate
long-duration ictal-like discharge.
Conclusions: Zebrafish offers a powerful tool for the
identification and study of a genetic basis for seizure
resistance. Key Words: Seizure—PTZ—Mutagenesis—
Electrophysiology—Forward genetics—Screen—Behavior.
Zebrafish as a Simple Vertebrate Organism for Epilepsy Research (3 paginas disponiveis do
livro no site- Scott Barabanhttp://www.springerlink.com/content/r788763k17066570/#section=67445&page=1)
Review
Transgenic zebrafish models of neurodegenerative diseases
Sager JJ, Bai Q, Burton EA
Abstract Since the introduction of the zebrafish as a
model for the study of vertebrate developmental biology, an
extensive array of techniques for its experimental manipulation
and analysis has been developed. Recently it has
become apparent that these powerful methodologies might
be deployed in order to elucidate the pathogenesis of human
neurodegenerative diseases and to identify candidate therapeutic
approaches. In this article, we consider evidence that
the zebrafish central nervous system provides an appropriate
setting in which to model human neurological disease and
we review techniques and resources available for generating
transgenic models. We then examine recent publications
showing that appropriate phenotypes can be provoked in the
zebrafish through transgenic manipulations analogous to
genetic abnormalities known to cause human tauopathies,
polyglutamine diseases or motor neuron degenerations.
These studies show proof of concept that findings in zebrafish
models can be applicable to the pathogenic mechanisms
underlying human diseases. Consequently, the prospects for
providing novel insights into neurodegenerative diseases by
exploiting transgenic zebrafish models and discovery-driven approaches seem favorable.
THE ZEBRAFISH
SCIENCE MONITOR
CHARACTERIZATION OF A CELL LINE
DERIVED FROM ZEBRAFISH
(BRACHYDANIO RERIO) EMBRYOS
By Wolfgang Driever and Zehava Rangini; Cardiovascular Research Center, Massachusetts
General Hospital, 149 Thirteenth St., Charlestown, MA 02129, USA
During the last decade, zebrafish (Brachydanio rerio) have emerged as a
novel and attractive system to study embryogenesis and organogenesis in
vertebrates. The main reason is that both extensive genetic studies and
detailed embryological analysis are possible using this small tropical fresh
water teleost. However, in vitro analysis using cell culture or molecular
genetics are still far less advanced than in other vertebrate systems.
We report the generation and characterization of a fibroblast like cell line,
ZF4, derived from one day old zebrafish embryos. The hyperploid cell line
has been stable in multiple passages for more than two years now and is the
first zebrafish cell line that can be maintained in conventional medium containing
mammalian serum.
Using a series of plasmids for expression of a marker gene, we evaluate in
ZF4 cells the relative strength of expression from several different viral, fish
and mammalian promoters. Stable integration can be obtained by using G418
selection. We hope that our cell line will be a useful tool for the analysis of
gene regulation in zebrafish
Using Gene-History and Expression Analyses to Assess the Involvement of LGI Genes in
Human Disorders
Gu W, Gibert Y, Wirth T, Elischer A, Bloch W, Meyer A, Steinlein OK, Begemann G
Abstract
Mutations in the leucine-rich, glioma-inactivated 1 gene, LGI1, cause autosomal-dominant
lateral temporal lobe epilepsy via unknown mechanisms. LGI1 belongs to a subfamily of
leucine-rich repeat genes comprising four members (LGI1–LGI4) in mammals. In this study,
both comparative developmental as well as molecular evolutionary methods were applied to
investigate the evolution of the LGI gene family and, subsequently, of the functional
importance of its different gene members. Our phylogenetic studies suggest that LGI genes
evolved early in the vertebrate lineage. Genetic and expression analyses of all five zebrafish
lgi genes revealed duplications of lgi1 and lgi2, each resulting in two paralogous gene copies
with mostly nonoverlapping expression patterns. Furthermore, all vertebrate LGI1 orthologs
experience high levels of purifying selection that argue for an essential role of this gene in
neural development or function. The approach of combining expression and selection data
used here exemplarily demonstrates that in poorly characterized gene families a framework
of evolutionary and expression analyses can identify those genes that are functionally most
important and are therefore prime candidates for human disorders.
A FISHY EPILEPSY MODEL
by Jack Parent, MD
COMMENTARY
Research into epilepsy mechanisms primarily involves studies
of rodents. Other mammalian species are occasionally
investigated, as is mammalian tissue grown as individual neural
cells or brain slices in the dish. Simpler vertebrates have not been
used as model systems to study epilepsy. Many argue that their
nervous systems are too primitive to generate seizures or that
potential seizure-like activity in these models has little relevance
to human epilepsy. The conservation of many neural functions
among vertebrates, however, suggests that fish and other simpler
vertebrates may provide useful models for a variety of neurological
disorders. Indeed, studies of simpler vertebrates, such as
zebrafish, have shed light on brain developmental mechanisms
in mammals. In this regard, Baraban and colleagues examine
the feasibility of using developing zebrafish larvae as an epilepsy
model system.