Digest: How do nonnative frugivorous birds adapt to life in O'ahu?*

Species adapt to the selective pressures of novel environments. Here, Gleditsch and Sperry tested whether four nonnative frugivorous bird species on the Hawaiian island of O'ahu diverged morphologically from their ancestral populations. They found that all four species significantly diverged from populations in their native ranges, with a general trend of smaller body size and larger bills. These differences were likely due to a combination of adaptive and nonadaptive processes.     

Nonelectrolyte permeability of liposomes of hydroxyfatty acid-containing phosphatidylcholines

Two phosphatidylcholines containing hydroxylated fatty acids, 1-palmitoyl-2-[5-hydroxy-6,8,11,14-eicosatetraenoyl]-sn-glycero-3- phosphocholine (1-palm-2-5HETE PC) and 1-palmitoyl-2-[15(S)-hydroxy-5,8,11,13- eicosatetraenoyl]-sn-glycero-3-phosphocholine (1-palm-2-15HETE PC), and one phosphatidylcholine containing nonhydroxylated fatty acids, 1-palmitoyl-2-arachidonyl-sn-glycero-3-phosphocholine (1-palm-2-arach PC) were synthesized. Permeation of small nonelectrolytes (glycerol, 1,2-propanediol, urea, methylurea, propionamide and dimethylformamide) was assessed in multilamellar liposomes containing these synthetic PCs plus egg yolk phosphatidycholine (EPC) in the presence and absence of cholesterol. In liposomes containing 23% cholesterol, 69.3% EPC and 7.7% of either 1-palm-2-5HETE PC or 1-palm-2-15HETE PC the permeability to small nonelectrolytes was 60 to 400% greater than in liposomes containing 23% cholesterol and 77% EPC. The HETE-containing PCs also increased permeability in liposomes without cholesterol but the effects were less striking. Addition of the synthetic PCs did not affect the energy of activation of permeation.     

Pili of Pasteurella multocida of porcine origin

Abstract Using electron microscopy, pili with at least two distinct morphologies were observed on strains of Pasteurella multocida isolated from pigs with atrophic rhinitis. Rigid pili were found on 60–80% of all cells observed. These pili had a strong tendency to lie flat along the side of the outer cell membrane of P. multocida and as a result frequently were difficult to see. After growth in vitro, piliated P. multocida cells produced few pili (approx. 3–5 per cell). Heavily piliated cells were occasionally observed. The second type of pili were curly and also were difficult to visualize. Cells from cultures containing piliated cells failed to attach to red blood cells and to immobilized mucus.     

Thermophilic methane production from cattle waste

Methane production from waste of cattle fed a finishing diet was investigated, using four 3-liter-working volume anaerobic digestors at 60 degrees C. At 55 degrees C a start-up culture, in which waste was the only source of bacteria, was generated within 8 days and readily adapted to 60 degrees C, where efficiency of methanogenesis was greater. Increasing the temperature from 60 to 65 degrees C tended to drastically lower efficiency. When feed concentrations of volatile solids (VS, organic matter) were increased in steps of 2% after holding for 1 months at a given concentration, the maximum concentrations for efficient fermentation were 8.2, 10.0, 11.6, and 11.6% for the retention times (RT) of 3, 6, 9, and 12 days, respectively. The VS destructions for these and lower feed concentrations were 31 to 37, 36 to 40, 47 to 49 and 51 to 53% for the 3-, 6-, 9-, and 12-day RT digestors, respectively, and the corresponding methane production rates were about 0.16, 0.18, 0.20, and 0.22 liters/day per g of VS in the feed. Gas contained 52 to 57% methane. At the above RT and feed concentrations, alkalinity rose to 5,000 to 7,700 mg of CaCo3 per liter (pH to 7.5 to 7.8), NH3 plus NH4+ to 64 to 90 mM, and total volatile acids to 850 to 2,050 mg/liter as acetate. The 3-day RT digestor was quite stable up to 8.2% feed VS and at this feed concentration produced methane at the very high rate of 4.5 liters/day per liter of digestor. Increasing the percentage of feed VS beyond those values indicated above resulted in greatly decreased organic matter destruction and methane production, variable decrease in pH, and increased alkalinity, ammonia, and total volatile acid concentrations, with propionate being the first to accumulate in large amounts. In a second experiment with another lot of waste, the results were similar. These studies indicate that loading rates can be much higher than those previously thought useful for maximizing methanogenesis from cattle waste.     

Nature of the Sendai virus receptor: glycoprotein versus ganglioside.

Gangliosides were compared with glycoproteins as potential receptors for Sendai virus by incorporating measured amounts of the glycoconjugates into lecithin-cholesterol liposomes and measuring binding by a hemagglutination assay with sheep erythrocytes. HeLa cell gangliosides showed no binding activity toward the virus up to 15 micrograms of sialic acid per 5 mumol of lecithin-cholesterol, whereas HeLa cell glycoproteins incorporated into similar liposomes caused avid virus binding below 1 microgram of sialic acid. These sialoglycoproteins could be separated from the bulk of cell proteins by multiple chloroform-methanol extractions. Purified rat brain gangliosides at a level of 120 micrograms of sialic acid in liposomes did not bind virus, whereas chloroform-methanol-extracted rat brain proteins caused only marginal binding. Bovine brain gangliosides differed slightly from the rat brain mixture in showing weak binding properties. Our results thus indicate that glycoproteins, rather than gangliosides, are the natural receptors for Sendai virus and that tissues differ as to the quantity of such protein receptors.     

Escherichia coli 987P pilus: purification and partial characterization

The Escherichia coli somatic pilus, 987P, has been purified after removal by homogenization from a 987P+ enterotoxigenic E. coli. Cell-free pili were precipitated by the addition of MgCl2, collected, and dissolved in MgCl2-free buffer. Five cycles of precipitation and dissolving resulted in a preparation of 987P that was judged to be homogeneous based on electron microscopy and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In the electron microscope, 987P was rod shaped, having a diameter of 7 nm and an apparent axial hole. Cells and membrane vesicles were not observed in the purified pilus preparation. Electrophoresis of 987P through sodium dodecyl sulfate-polyacrylamide gels resulted in a single band when the sample was denatured in the absence of mercaptoethanol and in two bands when the sample was denatured in the presence of mercaptoethanol. The calculated molecular weight of 987 was variable, depending upon the polyacrylamide concentration and whether mercaptoethanol was included in the denaturing solution. Chemically, 987P is composed primarily of protein but also contains an unidentified amino sugar. The amino terminal amino acid of 987P is alanine and its isoelectric point is pH 3.7. 987P possesses no detectable hemagglutinating activity.     

Global biostratigraphic comparison and correlation of an early Cisuralian palynoflora from Bolivia

This paper presents new data about Early Permian (Cisuralian) strata, palynostratigraphy and absolute dating from the Copacabana Formation in central Bolivia. Recent stratigraphic and palynologic data from marine and transitional rocks at Apillapampa refine the age of Cisuralian palynomorphs in South America. Twelve samples interbedded with five volcanic ashes (processed and productive) yielded 94 palynomorph species arranged in two informal palynoassemblages: the lower assemblage Vittatina costabilis corresponds to one sample near the base of the Copacabana Formation and the upper Lueckisporites virkkiae assemblage occurs in overlying marine and coal-bearing transitional intervals. Ages were also independently refined by a modern review of conodonts, fusulinids, along with those U–Pb radiometric ages (Isotope Dilution Thermal Ionization Mass Spectrometry [ID-TIMS] of zircon-bearing interbedded tuffs). These data suggest that the lower marine member of the Copacabana Formation at this location is Asselian and Sakmarian. Lueckisporites virkkiae is a key species of palynomorph utilised in South American and global Permian biostratigraphic reconstructions. Hence, a thorough global comparison of these palynofloras and correlations is addressed in this contribution, considering first appearances of mainly cosmopolitan diagnostic taxa. Correlations are established with many similar Permian palynofloras, some also constrained with radiometric data, in South America (Brazil, Uruguay and Argentina) and elsewhere.     

Massive-Scale Gene Co-Expression Network Construction and Robustness Testing Using Random Matrix Theory

The study of gene relationships and their effect on biological function and phenotype is a focal point in systems biology. Gene co-expression networks built using microarray expression profiles are one technique for discovering and interpreting gene relationships. A knowledge-independent thresholding technique, such as Random Matrix Theory (RMT), is useful for identifying meaningful relationships. Highly connected genes in the thresholded network are then grouped into modules that provide insight into their collective functionality. While it has been shown that co-expression networks are biologically relevant, it has not been determined to what extent any given network is functionally robust given perturbations in the input sample set. For such a test, hundreds of networks are needed and hence a tool to rapidly construct these networks. To examine functional robustness of networks with varying input, we enhanced an existing RMT implementation for improved scalability and tested functional robustness of human (Homo sapiens), rice (Oryza sativa) and budding yeast (Saccharomyces cerevisiae). We demonstrate dramatic decrease in network construction time and computational requirements and show that despite some variation in global properties between networks, functional similarity remains high. Moreover, the biological function captured by co-expression networks thresholded by RMT is highly robust.