Natural variation of model mutant phenotypes in Ciona intestinalis.
BACKGROUND
The study of ascidians (Chordata, Tunicata) has made a considerable contribution to our understanding of the origin and evolution of basal chordates. To provide further information to support forward genetics in Ciona intestinalis, we used a combination of natural variation and neutral population genetics as an approach for the systematic identification of new mutations. In addition to the significance of developmental variation for phenotype-driven studies, this approach can encompass important implications in evolutionary and population biology.


RESULTS
Here, we report a preliminary survey for naturally occurring mutations in three geographically interconnected populations of C. intestinalis. The influence of historical, geographical and environmental factors on the distribution of abnormal phenotypes was assessed by means of 12 microsatellites. We identified 37 possible mutant loci with stereotyped defects in embryonic development that segregate in a way typical of recessive alleles. Local populations were found to differ in genetic organization and frequency distribution of phenotypic classes.


CONCLUSIONS
Natural genetic polymorphism of C. intestinalis constitutes a valuable source of phenotypes for studying embryonic development in ascidians. Correlating genetic structure and the occurrence of abnormal phenotypes is a crucial focus for understanding the selective forces that shape natural finite populations, and may provide insights of great importance into the evolutionary mechanisms that generate animal diversity.
Laboratory of Biochemistry and Molecular Biology, Stazione Zoologica Anton Dohrn, Naples, Italy. sordino@szn.it
Paolo
P
Sordino
Nikos
N
Andreakis
Euan R
ER
Brown
Nicola I
NI
Leccia
Paola
P
Squarzoni
Raffaella
R
Tarallo
Christian
C
Alfano
Luigi
L
Caputi
Palmira
P
D'Ambrosio
Paola
P
Daniele
Enrico
E
D'Aniello
Salvatore
S
D'Aniello
Sylvie
S
Maiella
Valentina
V
Miraglia
Monia Teresa
MT
Russo
Gerarda
G
Sorrenti
Margherita
M
Branno
Lucio
L
Cariello
Paola
P
Cirino
Annamaria
A
Locascio
Antonietta
A
Spagnuolo
Laura
L
Zanetti
Filomena
F
Ristoratore
D000818:Animals; D002938:Ciona intestinalis / Q000235:genetics / Q000502:physiology*; D014644:Genetic Variation; D005828:Genetics, Population; D018895:Microsatellite Repeats / Q000235:genetics; D009154:Mutation; D010641:Phenotype