MOLECULAR REPRODUCTION AND DEVELOPMENT 66:256–263 (2003) Role of Substrate on Larval Development of the Freshwater Teleost Pelvicachromis pulcher FRANCESCA MARADONNA, 1 GIORGIO BAVESTRELLO, 1 MARCO CARDINALI, 1 IKE OLIVOTTO, 1 CARLO CERRANO, 2 MARCO GIOVINE, 3 AND OLIANA CARNEVALI 1 * 1 Dipartimento di Scienze del Mare, Universita`Politecnica delle Marche, Via Brecce Bianche, I-60131 Ancona, Italy 2 Dip.Te.Ris., Universita`di Genova, Corso Europa 26, I-16132 Genova, Italy 3 CNR-Direzione Progetto Finalizzato Biotecnologie, Via Leon Battista Alberti 4, 16132 Genova, Italy ABSTRACT It is known that, in an aquatic environment, the mineralogical composition of the substrate can affect the structure of settled commu- nities. In marine environments, the presence of quartz negatively influences the formation of biofilm, as well as the selection and the colonization of the substrate by benthic organisms. Direct laboratory observation re- vealed that the freshwater teleost Pelivicachromis pulcher selects, when available, nonquartzitic brood- ing substrate. To monitor the effects of substrate on larvae development, ten lots of embryos were distribut- ed in grid nurseries; carbonatic gravel was laid in five of the nurseries, while freshly fractured quartz gravel was used in the remaining ones. All the embryos laid in the two nurseries hatched, and 90% of the carbonate de- veloping larvae reached adulthood, while 100% of those reared on quartz grain died 120 hr post hatching. Examination was made, both in larvae developed on carbonatic substrates and in those developed on quartz substrates, of the expression of the fetal growth factor, the insulin growth factor-II (IGF-II), of the molecular chaperone, the heat shock protein 70 (HSP70), which is involved in the folding of the nascent polypeptide chain, of the key enzyme of the glycolytic path- way, the glyceraldehyde-3-phosphate dehydrogenase (GADPH), and of the housekeeping gene, the b-actin. All the data were normalized against 18S RNA expres- sion. In larvae reared on quartz substrate, the genes IGF-II and the b-actin showed a lower expression, while the GADPH was totally suppressed and the ex- pression of HSP70 increased. In conclusion, the data presented in this article demonstrated, for the first time, that the presence of quarzitic substrates is suffi- cient to stop larvae development through the inhibition of gene transcription in this African cichlid, leading to its death. Mol. Reprod. Dev. 66: 256–263, 2003. ß 2003 Wiley-Liss, Inc. Key Words: IGF-II; b-actin; HSP70; GADPH; cichlid; quartz INTRODUCTION Biomineralogical studies have revealed a wide range of interactions between biological systems with differ- ent levels of complexity (cell, organism, species, and community) and minerals. With regard to marine communities living on hard substrates, it has been shown that, under equal chemical–physical conditions (exposure, currents, trophism, etc.), there are signifi- cant differences in the specific abundance of marine benthic populations which grow on carbonates as com- pared to those living on siliceous substrates. It has also been shown that substrate selection by sessile infaunal organisms during metamorphosis of dispersion phases (larvae, asexual propagules) is likely to be determined by the nature of the substrate. In carbonatic sands arti- ficially enriched with different percentages of quartz, the specific abundance of meiobenthic populations is inversely proportional to the level of the quartz (Cerrano et al., 1999). Moreover, planulae of a hydroid (Eudendrium glomeratum) selectively settle on calcar- eous substrates, avoiding quarzitic ones (Bavestrello et al., 2000), while recent studies on the growth rates of diatoms show that different forms of silica affect cell development. Studies on the interactions between biological and mineral systems need to focus on larvae and their ecology. Larval ability to select a type of substrate and the subsequent interactions have major ecological implications. Indeed, the presence and distribution of a species in a certain ecosystem depends on more than just random dispersion events. Habitat structure, particularly the substrate type, is important in the life cycle of fish since it affects the distribution and availability of food, spawning ground, and refuges from predation (Inoue and Nakano, 1994; Tupper and Boutilier, 1995). It was recently demonstrated through observation in the field that the mineralogical nature of the substrate can determine the distribu- tion of two marine species, the Serranus scriba and the Serranus cabrilla—the former found on carbona- tic substrates and the latter on quartzitic ones—by ß 2003 WILEY-LISS, INC. Grant sponsor: Fondi d’Ateneo 2001; Grant sponsor: ASI; Grant number: I/R/336/02. *Correspondence to: Dr. Oliana Carnevali, Dipartimento di Scienze del Mare, Universita ` Politecnica delle Marche, Via Brecce Bianche 60131, Ancona, Italy. E-mail: carnevali@unian.it Received 3 April 2003; Accepted 10 June 2003 Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mrd.10351