The biological role of pituitary adenylate cyclase‐activating polypeptide (PACAP) in growth and feeding behavior in juvenile fish

To date, many technologies have been developed to increase efficiency in aquaculture, but very few successful biotechnology molecules have arrived on the market. In this context, marine biotechnology has an opportunity to develop products to improve the output of fish in aquaculture. Published in vivo studies on the action of the pituitary adenylate cyclase‐activating polypeptide (PACAP) in fish are scarce. Recently, our group, for the first time, demonstrated the biological role of this neuropeptide administrated by immersion baths in the growth and development of larval fish. In this work, we have evaluated the effects of recombinant Clarias gariepinus PACAP administration by intraperitoneal injection on growth performance and feeding behavior in juvenile fish. Our results showed the physiological role of this peptide for growth control in fish, including the juvenile stage, and confirm that its biological functions are well conserved in fish, since C. gariepinus PACAP stimulated growth in juvenile tilapia Oreochromis niloticus. In addition, we have observed that the growth‐promoting effect of PACAP in juvenile tilapia was correlated with higher GH concentration in serum. With regard to the neuroendocrine regulation of growth control by PACAP, it was demonstrated that PACAP stimulates food intake in juvenile tilapia. In general, PACAP appears to act in the regulation of the growth control in juvenile fish. These findings propose that PACAP is a prominent target with the potential to stimulate fish growth in aquaculture. Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd.     

Trypanosoma cruzi-specific immune responses in subjects from endemic areas of Chagas disease of Argentina

Trypanosoma cruzi-specific immune responses were evaluated in a total of 88 subjects living in areas endemic of Chagas disease of Argentina by IFN-γ ELISPOT assays and immunoblotting. Positive T. cruzi antigen-induced IFN-γ responses were detected in 42% of subjects evaluated (15/26 positive by conventional serology and 22/62 seronegative subjects). Using immunoblotting, T. cruzi-specific IgG reactivity was detected in all seropositive subjects and in 11% (7/61) of subjects negative by conventional serology. Measurements of T cell responses and antibodies by immunoblotting, in conjunction with conventional serology, might enhance the capability of detection of exposure to T. cruzi in endemic areas.     

Stenocereus zopilotensis Arreola-Nava and Terrazas (Cactaceae), a new species from Mexico

Stenocereus zopilotensis Arreola-Nava and Terrazas, a new species from the Zopilote Canyon, municipality of Zumpango del Rio in the center of the state of Guerrero (Mexico), is described and illustrated. This new species is compared toStenocereus quevedonis J. G. Ortega,S. fricii Sánchez-Mej., andS. pruinosus (Otto) Buxb. based on morphological similarity. Moreover, the new species grows sympatrically withS. pruinosus.     

Imaging filopodia dynamics in the mouse blastocyst

During mammalian development, the first cell lineage diversification event occurs in the blastocyst, when the trophectoderm (TE) and the inner cell mass (ICM) become established. Part of the TE (polar) remains in contact with the ICM and differs from the mural TE (mTE) which is separated from the ICM by a cavity known as the blastocoele. The presence of filopodia connecting ICM cells with the distant mural TE cells through the blastocoelic fluid was investigated in this work. We describe two types of actin-based cell projections found in freshly dissected and in vitro cultured expanding blastocysts: abundant short filopodia projecting into the blastocoelic cavity that present a continuous undulating behavior; and long, thin traversing filopodia connecting the mural TE with the ICM. Videomicroscopy analyses revealed the presence of vesicle-like structures moving along traversing filopodia and dynamic cytoskeletal rearrangements. These observations, together with immunolocalization of the FGFR2 and the ErbB3 receptors to these cell extensions, suggest that they display signal transduction activity. We propose that traversing filopodia are employed by mitotic mTE cells to receive the required signals for cell division after they become distant to the ICM.     

Correlation of protein functional properties in the crystal and in solution: the case study of T-state hemoglobin

The relevance of three-dimensional structures of proteins, determined by X-ray crystallography, is an important issue that is becoming even more critical in light of the Structural Genomics Initiative. As a case study, a detailed comparison of functional properties of the T quaternary states of genetically or chemically modified human hemoglobins (Hbs) in solution and in the crystal was performed. Oxygen affinities of Hbs in crystals correlate with the rate constants of their initial combination with carbon monoxide (CO) in solution, indicating that changes in ligand affinity caused by the modifications are similarly observed in both physical states.     

Presence of histone mRNA sequences in high molecular weight RNA of HeLa cells

Pulse-labeled HeLa cell RNA centrifuged under denaturing conditions was hybridized with DNA of recombinant phages containing sea urchin histone genes. This cross-hybridization showed the presence of histone mRNA sequences in high molecular weight RNA molecules. Treatment of the cells with actinomycin to stop RNA synthesis resulted in the rapid decay of this high molecular weight RNA followed by an increase of 9S histone mRNA in the cytoplasm.The results are consistent with the presence in HeLa cells of a high molecular weight precursor to histone messengers.     

Ultrastructural alterations in Tetrahymena pyriformis induced by growth on saturated phospholipids at 40.1 °C

Structural changes in Tetrahymena pyriformis, strain WH-14, induced by growth on saturated phospholipids at 40.1 °C, were studied by electron microscopy. Alterations in the ultrastructural organization of the cell membrane and surface regions were common. These alterations were characterized in the displacement of kinetosomes, the spatial disorientation and disorganization of cortical ridges and grooves, and the spatial disorientation of longitudinal and transverse microtubular ribbons. Irregular surface protrusions and multiple invaginations of alveolar membranes were among the most common features encountered. Disorganization of longitudinal microtubular ribbons was also a frequent encounter. The integrity of the ultrastructure of cell surface membranes and of the internal organization and ultrastructure of the kinetosomes, however, appeared to be unaltered. Other alterations included those of a number of cytoplasmic organelles (e.g. mitochondria and endoplasmic reticulum), which showed characteristic changes in structural patterns.