World Congress of Malacology Antwerp ... - Unitas Malacologica

Using the Octopus retina to understand the cell biology of the eye:
Surprises and clues!
Robles, Laura J. 1 ; Kelly, Shannon 2
1. California State University, Dominguez Hills, Academic Programs, 1000 East
Victoria Street, Carson, CA 90747, USA,
Email: lrobles@csudh.edu
2. California State University, Dominguez Hills, Department of Biology, 1000 East
Victoria Street, Carson, CA 90747, USA,
Email: skelly@csudh.edu
Recent progress toward understanding the cell and molecular biology of degenerate eye diseases has
implicated the cytoskeleton found within retinal cells. Invertebrate retinas, particular those of
cephalopods, are excellent model systems in which to study the cytoskeleton, factors that control its
organization and mechanisms which disrupt the cytoskeleton leading to retinal degeneration.
In the retina of Octopus bimaculoides, microvilli that compose the light sensitive rhabdoms increase
in cross-sectional area in the dark and shrink in the light. Concomitantly, proteins involved in
phototransduction translocate within the rhabdom compartment. Using standard cell and molecular
techniques we have implicated signaling pathways involving the Rho GTPases in cytoskeletal
organization and have further determined that expression of mRNAs for retinal proteins is regulated
at the translational level by “masking and unmasking” processes first demonstrated in oocytes.
Our results show that in the dark, Rho GTPase is activated and binds to the rhabdom membrane and
may initiate signaling pathways leading to growth of rhabdomere microvilli. In the light, Rho is
present in the soluble fraction, is inactivated and likely bound to a Rho GDI. Receptors involved in
the activation of Rho in the dark are undetermined and may involve rhodopsin or other membrane
proteins. Western blot analysis identified the trans-acting cytoplasmic polyadenylation binding
protein (CPEB) in retinal extracts. CPEB functions in the masking and unmasking of maternal
mRNAs during early development by binding to the cytoplasmic polyadenylation element (CPE)
located within the 3’ UTR of mRNAs. 3’RACE analysis of S-crystallin mRNA in octopus retinal
extracts revealed CPE-like sequences located within the 3’ UTRs of two 326-bp S-crystallin variants.
Our results can be applied to vertebrate retinas to unravel control of photoreceptor cytoskeletons and
expression of retinal-specific mRNAs.
Supported by NIH/NIGMS/MBRS GM08156
Soil mollusc response to different fertilized strategies for grass production in Galiza (NW
Spain)
Rodríguez, Teresa 1 ; Moreira, Mariana 2 ; López-Mosquera, Elvira 3 ; Carral, Emilio 2
1. Dpto. Zooloxía e Antropoloxía Física, Escola Politécnica Superior, Universidade de Santiago de
Compostela, 27002 Lugo, Spain,
Email: babosa@usc.es
2. Dpto. Bioloxía Celular e Ecoloxía, Escola Politécnica Superior, Universidade de Santiago de
Compostela, 27002 Lugo,
Email: marianam@usc.es, Email: evcarral@lugo.usc.es
3. Dpto. Produción Vexetal, Escola Politécnica Superior, Universidade de Santiago de Compostela,
27002 Lugo, Spain,
Email: ellomo@lugo.usc.es
There is already much research about the effects of the use of different sources of organic and
mineral fertilizers on the physical-chemical properties of the soil, but less is known about their effects
on the edaphic fauna. The main aim of this essay is to compare the effects caused by different
fertilization strategies on soil mollusc community, based on the application of: i) dairy sludge, ii)
cattle slurry, iii) poultry dung and iv) chemical fertilizers (N,P,K addition). The four types of
fertilization are compared among themselves and with non- fertilized plots of grassland. The research
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