Structure of the spectrin-actin binding site of erythrocyte protein 4.1

The complete primary structure of the functional site of erythrocyte protein 4.1 involved in spectrin-actin associations has been determined. The sequence of this domain, which contains 67 amino acids and has a molecular mass of 8045 daltons, has been obtained by NH2-terminal sequence analysis of an 8-kDa chymotryptic peptide, three endoproteinase lysine C-cleaved peptides and two peptides obtained by Staphylococcus aureus protease V8 cleavage. All peptides including the 8-kDa domain peptide were purified by reverse-phase high performance liquid chromatography. Antibodies against two different synthetic peptides of the 8-kDa domain are able to inhibit the association between protein 4.1, spectrin, and F-actin, corroborating that the 8-kDa domain is responsible for the formation of a ternary complex. A computer search of the 8-kDa sequence with the National Biomedical Research Foundation database did not detect any significant homologies to known sequences. Protein 4.1 is not related to any known proteins and may represent a new protein superfamily.     

Growth-induced mass flows in fungal networks

Cord-forming fungi form extensive networks that continuously adapt to maintain an efficient transport system. As osmotically driven water uptake is often distal from the tips, and aqueous fluids are incompressible, we propose that growth induces mass flows across the mycelium, whether or not there are intrahyphal concentration gradients. We imaged the temporal evolution of networks formed by Phanerochaete velutina, and at each stage calculated the unique set of currents that account for the observed changes in cord volume, while minimizing the work required to overcome viscous drag. Predicted speeds were in reasonable agreement with experimental data, and the pressure gradients needed to produce these flows are small. Furthermore, cords that were predicted to carry fast-moving or large currents were significantly more likely to increase in size than cords with slow-moving or small currents. The incompressibility of the fluids within fungi means there is a rapid global response to local fluid movements. Hence velocity of fluid flow is a local signal that conveys quasi-global information about the role of a cord within the mycelium. We suggest that fluid incompressibility and the coupling of growth and mass flow are critical physical features that enable the development of efficient, adaptive biological transport networks.     

Differential phosphorylation of multiple sites in protein 4.1 and protein 4.9 by phorbol ester-activated and cyclic AMP-dependent protein kinases

The phosphorylation of the membrane skeleton components protein 4.1 and protein 4.9 in intact erythrocytes is shown to increase in the presence of either 1 microM 12-O-tetradecanoyl phorbol 13-acetate or 2 mM dibutyryl cAMP. The phosphorylation induced by these protein kinase activators is compared by two-dimensional tryptic peptide mapping. In both proteins, the pattern of peptides phosphorylated in the presence of 12-O-tetradecanoyl phorbol 13-acetate differs from the pattern of peptides phosphorylated in the presence of dibutyryl cAMP. The relative locations of the phosphorylated sites on protein 4.1 have been determined using limited proteolysis by alpha-chymotrypsin.     

Identification of the functional site of erythrocyte protein 4.1 involved in spectrin-actin associations

Peptides produced by mild chymotryptic digestion of human erythrocyte protein 4.1 mimic the ability of intact 4.1 to promote the binding of spectrin to F-actin. This complex-promoting activity was found to reside in an 8-kDa peptide which was fully functional when dissociated from other protein 4.1-derived peptides, indicating that noncovalent complexes of multiple peptides were not essential for activity. The 8-kDa peptide was incorporated into a ternary complex with spectrin and F-actin in approximately stoichiometric amounts. Amino acid composition and two-dimensional peptide mapping show that the 8-kDa active peptide is located within the 10-kDa region of protein 4.1 which contains a cAMP-dependent phosphorylated site.     

Theoretical calculation of partition coefficients of dimethoxypyrimidinylsalicylic acids

Despite their importance as herbicides, dimethoxypyrimidinylsalicylic acids has been poorly characterized from a physical-chemical point of view. This lack of information has prevented the assessment of their impact in the environment once they are released. In this study, environmentally important properties (free energy of solvation, Henry’s law constant, octanol/air, and octanol/water partition coefficients) of 39 dimethoxypyrimidinylsalicylic derived compounds are calculated by density functional theory (DFT) methods at B3LYP/6-31G(d,p) level of theory using the Poisson-Boltzmann solvation model. These properties have not been reported previously for this family of compounds, neither experimentally or theoretically.     

The Identification of Congeners and Aliens by Drosophila Larvae

We investigated the role of Drosophila larva olfactory system in identification of congeners and aliens. We discuss the importance of these activities in larva navigation across substrates, and the implications for allocation of space and food among species of similar ecologies. Wild type larvae of cosmopolitan D. melanogaster and endemic D. pavani, which cohabit the same breeding sites, used species-specific volatiles to identify conspecifics and aliens moving toward larvae of their species. D. gaucha larvae, a sibling species of D. pavani that is ecologically isolated from D. melanogaster, did not respond to melanogaster odor cues. Similar to D. pavani larvae, the navigation of pavani female x gaucha male hybrids was influenced by conspecific and alien odors, whereas gaucha female x pavani male hybrid larvae exhibited behavior similar to the D. gaucha parent. The two sibling species exhibited substantial evolutionary divergence in processing the odor inputs necessary to identify conspecifics. Orco (Or83b) mutant larvae of D. melanogaster, which exhibit a loss of sense of smell, did not distinguish conspecific from alien larvae, instead moving across the substrate. Syn ^97CS and rut larvae of D. melanogaster, which are unable to learn but can smell, moved across the substrate as well. The Orco (Or83b), Syn ^97CS and rut loci are necessary to orient navigation by D. melanogaster larvae. Individuals of the Trana strain of D. melanogaster did not respond to conspecific and alien larval volatiles and therefore navigated randomly across the substrate. By contrast, larvae of the Til-Til strain used larval volatiles to orient their movement. Natural populations of D. melanogaster may exhibit differences in identification of conspecific and alien larvae. Larval locomotion was not affected by the volatiles.     

Stone Throwing as a Sexual Display in Wild Female Bearded Capuchin Monkeys,Sapajus libidinosus

Capuchin monkeys (Sapajus spp.) in captive settings frequently manipulate and throw objects. In the wild, they may push or drop stones and sticks toward targets during inter- or intraspecific threat displays. In addition, female capuchin monkeys exhibit a broad repertoire of behaviors during their proceptive period, including facial expressions, vocalizations, stereotyped body postures, and touch-and-run behavior. This study reports stone throwing as a newly-described communicative behavior during the proceptive display of females in a group of bearded capuchin monkeys (S. libidinosus) in Serra da Capivara National Park, Brazil. During a two-year study, three females from one group were seen throwing stones at males during their proceptive phase. After this period, three other females in the same group exhibited the same behavior. Although it may be possible that this pattern is the result of several independent innovations by each female, the apparent absence of this behavior in other groups leads us to suggest that we have documented the diffusion of a new behavioral trait or tradition within this capuchin social group.