Abstracts / Comparative Biochemistry and Physiology, Part A 148 (2007) S86–S90
19.3. Peptide transport systems in crustacean models 1
Verri, Tiziano and 2Ahearn, Gregory Laboratory of General Physiology, Department of Biological & Environmental Sciences & Technologies, University of Salento (formerly University of Lecce), Via Provinciale Lecce-Monteroni, 73100 Lecce, Italy 2 Department of Biology, University of North Florida, 4567 St. Johns Bluff Road, South, Jacksonville, FL 32224, USA 1
Cellular uptake of small peptides and peptide-like molecules is mediated by membrane transport proteins of the so-called PTR family (Steiner et al., Mol. Microbiol. 16:825–834, 1995). PTR proteins have been reported from bacteria to humans, but limited information is available from invertebrate models. In 1997, the first invertebrate peptide transporter gene (opt1, for oligo peptide transporter 1) was identified in the fruit fly, Drosophila melanogaster (Amrein and Axel, Cell 88:459, 1997). opt1 encodes a H+-dependent dipeptide transporter (Roman et al., Am. J. Physiol. 275:C857, 1998). After that, three peptide transporters (opt1, opt2 and opt3) were cloned from the nematode Caenorhabditis elegans (Fei et al., Biochem. J. 332:565, 1998; Fei et al., J. Biol. Chem. 275:9563, 2000). While opt1(pep-1) and opt2 (pep-2) operate as H+-dependent peptide transporters, opt3 predominantly functions as a H + -channel. Due to their phylogenetic position among invertebrates, crustaceans might contribute novel insights into the evolution of the molecular structure and function of the PTR transporters. Recently, using the American lobster Homarus americanus, peptide transport was revealed at the intestinal level of a crustacean model. Interactions between peptide, L-His and Zn2+ flux were unexpectedly observed at a not yet identified carrier that binds and transports such solutes simultaneously. doi:10.1016/j.cbpa.2007.06.224
19.4. Seasonal variation on the energetic metabolism of crustaceans Vinagre, A.S. Laboratório de Histofisiologia Animal, ULBRA, Brazil
[email protected] The energetic metabolism of crustaceans presents high intraand inter-specific variability, which makes it difficult to determine a standard metabolic profile. This variability is explained by the many environmental variables that the animal is exposed to during the year, depending on the geographical region. It is also influenced by the stage of the moulting cycle, sexual maturity, reproductive process, feeding state, and activity level. The aim of this presentation is to review the main metabolic variations presented by different crustaceans along the year, in different kinds of habitats. doi:10.1016/j.cbpa.2007.06.225
S87
19.5. Calcium transport in crabs: A comparative study between brackish and freshwater environments Blotta-Baptista, B. and Zanotto, F.P. University of São Paulo, Brazil
[email protected] Calcium (Ca) is essential for crustaceans since their growth is related to Ca deposition in the exoskeleton. Freshwater and brackish animals constantly face physiological challenges to acquire this ion. The aim of this study was to compare calcium transport in hepatopancreas, gills, and antennal glands of a freshwater crab (Dilocarcinus pagei) and a brackishwater crab (Ucides cordatus). Cells were mechanically dissociated in isosmotic Ca2+-free buffer and then loaded with intracellular calcium dye Fluo-3 AM. Fluorescence variation was recorded as calcium was added in the external medium. For brackishwater crab, calcium transport in hepatopancreas was described by Michaelis–Menten kinetics with a diffusional component (Km = 0.16 mM/n = 4), inhibited by amiloride (around 30%). Gills and antennal glands exhibited 3-parameter Michaelis– Menten kinetics (Km = 4.78 and 2.62, respectively/n = 4), and inhibited significantly by amiloride (around 50%). For the freshwater crab, calcium transport in hepatopancreas was described by a 3-parameter Michaelis–Menten kinetics (Km = 0,43 /n = 4). Gills and antennal gland, on the other hand, exhibited Hill kinetics (nH = 2 and 3/n = 5 and 6, respectively). Calcium transport was also inhibited significantly by amiloride (around 60%) in all tissues of this crab. These results suggest the participation of an amiloride-sensitive Na/Ca2+ exchanger for both crabs. Hill's coefficient indicates a cooperative calcium transport in gills and antennal gland of the freshwater crab only. Calcium influx by gills and antennal glands shows a more complex mechanism in freshwater compared to brackishwater crabs. doi:10.1016/j.cbpa.2007.06.226
19.6. Gluconeogenesis in gills of Chasmagnathus granulatus submitted to hyper-osmotic or hypo-osmotic stress in winter and summer Chittó, A.L.F., Kucharski, L.C., and da Silva, R.S.M. PUCRS, Brazil
[email protected] In order to investigate the role of gluconeogenesis during acclimatization to osmotic stress, it was measured, in vitro, the incorporation of [U-14C]-alanine into glucose in anterior (AG) and posterior gills (PG) from the estuarine crab C. granulatus submitted to hypo- (HO) or hyper-osmotic (HE) stress in summer and winter. AG has respiratory function while PG has osmoregulatory functions. Male crabs were kept in aquarium at
