A landscape approach to conservation of birds

Landscape ecology as a discipline in science is rather young. However its principles appear promising in outlining conservation strategies including a wide range of organisms, particularly birds. Birds due to their mobility use a variety of environmental resources, especially habitats. However, currently these habitats are only available in patches over most of the tropical world. Further whatever is left is under constant human pressure. This paper, therefore, addresses this problem and suggests means of dealing with it using the landscape approach as outlined by landscape ecology. The landscape approach starts with the realization that patches of habitats are open and interact with one another. Corridors of trees along roads, hedgerows and canals in a landscape can aid in the movement of species. Hence the landscape approach considers patches of habitats as interacting elements in the large matrix of the landscape. The landscape approach also integrates concepts. It puts together often debated issues such as whether to preserve maximum species diversity, to maximize representativeness, or to preserve only the valuable species. Based on a case study of the Uttara Kannada district in Karnataka, these oft-opposing views and complications can be dealt with practically and synthesized into a conservation strategy for the diverse avifauna of the Western Ghats.     

New conformational constraints in isotopically (13C) enriched oligosaccharides

Multidimensional heteronuclear NMR studies have been applied to the resonance assignment and conformational analysis of 13C-enriched Neu5Acalpha2-3Galbeta1-4Glc. It is demonstrated that three-dimensional ROESY-HSQC experiments provide through-space distance restraints which cannot be observed with conventional homonuclear 1H techniques due to resonance overlap. In particular, connectivities demonstrating the existence of the "anti" conformation about the Galbeta1-4Glc glycosidic linkage are unambiguously observed. It is shown that 13C isotopic enrichment of the trisaccharide at a level >95% enables straightforward measurement of trans-glycosidic 1H-13C and 13C-13C coupling constants and a Karplus-type relation is derived for the latter. In total 15 conformational restraints were obtained for the trisaccharide in aqueous solution, all of which were in excellent agreement with theoretical parameters computed from a 5 ns molecular dynamics simulation of the glycan.      

Molecular characterization and phylogenetic relationships of a protein with potential oxygen-binding capabilities in the grasshopper embryo. A hemocyanin in insects?

Arthropodan hemocyanins, prophenoloxidases (PPOs), and insect hexamerins form a superfamily of hemolymph proteins that we propose to call the AHPH superfamily. The evolutionary and functional relationships of these proteins are illuminated by a new embryonic hemolymph protein (EHP) that is expressed during early stages of development in the grasshopper embryo. EHP is a 78-kDa soluble protein present initially in the yolk sac content, and later in the embryonic hemolymph. Protein purification and peptide sequencing were used to identify an embryonic cDNA clone coding for EHP. In situ hybridization identifies hemocytes as EHP-expressing cells. As deduced from the cDNA clone, EHP is a secreted protein with two potential glycosylation sites. Sequence analysis defines EHP as a member of the AHPH superfamily. Phylogenetic analyses with all the currently available AHPH proteins, including EHP, were performed to ascertain the evolutionary history of this protein superfamily. We used both the entire protein sequence and each of the three domains present in the AHPH proteins. The phylogenies inferred for each of the domains suggest a mosaic evolution of these protein modules. Phylogenetic and multivariate analyses consistently group EHP with crustacean hemocyanins and, less closely, with insect hexamerins, relative to cheliceratan hemocyanins and PPOs. The grasshopper protein rigorously preserves the residues involved in oxygen binding, oligomerization, and allosteric regulation of the oxygen transport proteins. Although insects were thought not to have hemocyanins, we propose that EHP functions as an oxygen transport or storage protein during embryonic development.      

Synthesis and problematic crystal structures of [Al(CH3CN)6][MCl6]3(CH3CN)3 (M=Ta, Nb or Sb)

Compounds of formula [Al(CH₃CN)₆][MCl₆]₃(CH₃CN)₃ (M=Ta (1); Nb (2); Sb (3)) have been synthesized from the reactions of MCl₅ and AlCl₃ in acetonitrile and characterized by X-ray crystallography. Complex 1 crystallizes in the tetragonal space group P4/mbm with a = B = 10.408(2), C = 7.670(3) Å, V = 830.9(4) ų and Z = 2/3. Complex 2 crystallizes in the tetragonal space group P4/mnc with a = B = 330(a), C = 15.320(3) ų V = 1634.8(4) ų and Z = 4/3. Complex 3 also crystallizes in the tetragonal space group P4/mnc with a = B = 10.313(1), C = 15.238(2) Å, V = 1621.0(1) ų and Z = 4/3. The non-integer Z values for complexes 1–3 result unusual problems of disorder and/or twinning in these crystal structures due to their high symmetry. The M---Cl distances range from 2.329(3) Å in the Ta complex to 2.355(1) Å in the Sb complex, while the Al---N distances are similar in all three complexes, ranging from 1.92(1) to 1.97(1) Å, respectively. Complexes 1–3 are the first structurally characterized complexes that contain a (hexaacetonitrile)aluminum(III) cation.     

Phage Peptide Libraries

Filamentous phage particles have been central in the construction of libraries displaying vast numbers of random peptides. These random peptides can be antigenically presented as fusions to coat proteins III and VIII of the phage. The isolation of ligate-reactive phage from an immense background of nonspecific phage is achieved by the biopanning process. Enrichment of reactive phage relative to unreactive phage occurs with alternate rounds of affinity selection to the desired molecular target and amplification of the specifically bound phage. This allows the isolation of rare binding species contained in the phage peptide libraries. Each phage particle contains the information in its genome pertaining to the type of random peptide insert displayed. Hence, the identification of binding motifs displayed on ligate-reactive phage is revealed by sequencing the relevant insert site in the phage genome. Phage peptide libraries have been used to isolate ligands to an array of protein ligates. The libraries have proved particularly effective in defining the binding sites of monoclonal antibodies and to some extent polyclonal sera. The analysis of the peptide insert sequences of a number of different clones of antibody binding phage can reveal a great deal about the nature and restriction of the amino acid residues critical for the antibody–antigen interaction.     

Unexpected Errors in Gas Chromatographic Analysis of Methane Production by Thermophilic Bacteria

Unexpected errors in methane measurement by gas chromatography occurred when samples at thermophilic temperatures were analyzed. With a standard curve prepared at room temperature (25°C), stoppered bottles incubated and sampled at 37 to 85°C showed more methane upon analysis than bottles incubated at 25°C: values at 50, 63, and 85°C were 109, 126, and 125%, respectively, of the 25°C value. All variation between 4 and 50°C can be explained by the temperature difference between culture bottle and sampling syringe, and the variation of methane concentration can be predicted by the gas law. Between 50 and 63°C, there was a more dramatic rise than predicted by theory. These variations are important to consider if thermophilic methane production is to be measured accurately. Methods to avoid errors are discussed.     

Pattern of organotin inhibition of methanogenic bacteria.

Seven organotin compounds and tin chloride were tested for their effects on the methanogenic bacteria Methanococcus thermolithotrophicus, Methanococcus deltae delta LH, and Methanosarcina barkeri 227. The methanogens were strongly inhibited by triethyltin, tripropyltin, and monophenyltin compounds, generally at concentrations below 0.05 mM. Less inhibition by tributyltin and diphenyltin was observed at levels below 0.1 mM, but complete inhibition was observed at a 1 mM concentration. Tin chloride inhibited all methanogens, with nearly complete inhibition at a 1 mM concentration. There was no inhibition by tetra-n-butyltin and triphenyltin compounds even at 2 mM, the highest concentration tested. The 50 and 100% inhibitory concentrations of all compounds were estimated; these values varied with both the compound tested and the bacterium tested. The 50% inhibitory concentration estimate generally decreased (i.e., giving a higher toxicity) as the total surface area of the alkyltin molecules decreased. These results differ considerably from those reported previously for aerobic microorganisms (G. Eng, E. J. Tierney, J. M. Bellama, and F. E. Brinckman, Appl. Organometallic Chem. 2:171-175, 1988), where a clear correlation between increasing total molecular surface area and increasing toxicity was documented with a variety of organisms. Using the same procedures as for the methanogens, we examined the effects of organotin compounds on Escherichia coli growing aerobically or anaerobically. The E. coli inhibition pattern clearly resembled that seen in the data of Eng et al., under both aerobic and anaerobic conditions.