Macaques preferentially attend to intermediately surprising information

Normative learning theories dictate that we should preferentially attend to informative sources, but only up to the point that our limited learning systems can process their content. Humans, including infants, show this predicted strategic deployment of attention. Here, we demonstrate that rhesus monkeys, much like humans, attend to events of moderate surprisingness over both more and less surprising events. They do this in the absence of any specific goal or contingent reward, indicating that the behavioural pattern is spontaneous. We suggest this U-shaped attentional preference represents an evolutionarily preserved strategy for guiding intelligent organisms toward material that is maximally useful for learning.     

Dietary zinc-methionine enhances mononuclear-phagocytic function in young turkeys

The ability of dietary zinc-methionine (Zn-Met) to enhance mononuclear-phagocytic function againstSalmonella arizona andenteritids was investigated in young turkeys. Feed/gain and body wt gain at 21 d of age were not affected by Zn-Met. The addition of 30 or 45 ppm Zn from Zn-Met to a Zn adequate diet significantly increased cutaneous basophil hypersensitivity to phytohemagglutinin-P. The clearance of intravenously administeredS. enteritidis from blood was not affected by 30 ppm of supplemental Zn from Zn-Met. However, 30 ppm Zn from Zn-Met increased the reduction of intravenously administeredS. arizona from spleen. Percentages of myeloid and mononuclear-phagocytic cells before and afterS. enteritidis infection were not affected by supplemental Zn-Met. Turkeys supplemented with Zn-Met showed enhanced in vitro phagocytosis ofS. enteritidis by Sephadex-elicited abdominal exudate cells. The phagocytosis ofS. arizona was unaffected by Zn-Met.     

Identification by molecular cloning of two forms of the alpha-subunit of the human liver stimulatory (GS) regulatory component of adenylyl cyclase

Two DNA molecules complementary to human liver mRNA coding for the alpha-subunit of the stimulatory regulatory component Gs of adenylyl cyclase were cloned. One of the two forms is a full-length cDNA of 1614 nucleotides plus a poly(A) tail of 59 nucleotides. The deduced sequence of 394 amino acids encoded by its open reading frame is essentially identical to that of the alpha-subunits of Gs identified by molecular cloning from bovine adrenals, bovine brain and rat brain. Two independent clones of the other type of cDNA were isolated. Both were incomplete, beginning within the open reading frame coding for the alpha s polypeptide. One codes for amino acids 5 through 394 and the other for amino acids 48 through 394 of the above described cDNA of 1614 nucleotides, and both have the identical 3'-untranslated sequence. They differ from the first cDNA, however, in that they lack a stretch of 42 nucleotides (numbers 214 through 255) and have nucleotides 213 (G) and 256 (G) replaced with C and A, respectively. This results in a predicted amino acid composition of another alpha-subunit of Gs that is shorter by 14 amino acids and contains two substitutions (Asp for Glu and Ser for Gly) at the interface between the deletion and the unchanged sequence. We call the smaller subunit alpha s1 and the larger alpha s2. This is the first demonstration of a structural heterogeneity in alpha s subunits that is due to a difference in amino acid sequence.     

Variation in the ribosomal internal transcribed spacers (ITS1 and ITS2) among eight taxa of the Mimulus guttatus species complex

The internal transcribed spacer region (ITS1 and ITS2) of the 18S-25S nuclear ribosomal DNA sequence and the intervening 5.8S region were sequenced from three individuals in each of eight taxa of the Mimulus guttatus species complex. Three discrete variants, or "types," of ITS sequences were found, among which 30%-40% of sites differed, compared with 1%-2% within types. Dot plots indicate that these types were not related by conspicuous rearrangements or inversions. More than one ITS type was often found in the same taxon, and two of three ITS types span species boundaries, indicating their presence prior to speciation. These ITS sequences showed essentially no positional homology with the nearest sequenced relative, tomato. In contrast, the 5.8S region was relatively unvaried, with 8 of 162 sites varied in the sample among all eight taxa. The phylogeny inferred by the most common ITS sequence type, rooted by the two other ITS types, agreed with isozymes in showing the distinctness of M. nudatus, M. laciniatus, and M. tilingii from the other five taxa.      

Beta beta homodimers exist in native rabbit skeletal muscle tropomyosin and increase after denaturation-renaturation.

Native tropomyosin from rabbit skeletal muscle (RSTm) consists mainly of alpha alpha and alpha beta coiled coils (alpha/beta approximately 3-4/1). In some extant studies, no beta beta molecules have been found. In this study, RSTm from several different preparations was disulfide cross-linked, both preparation and cross-linking being done under nondenaturing conditions. The cross-linked product was assayed for the presence of beta beta molecules cross-linked at both C36 and C190 (beta = beta). In such cross-linked RSTm, 3-8% beta = beta is detected by sodium dodecyl sulfate polyacrylamide gel electrophoresis, C4 reversed-phase high-performance liquid chromatography, and a free-solution capillary electrophoresis experiment. This percentage becomes approximately 4-10% beta beta when corrected for incomplete double cross-linking and is independent of protein concentration (0.1-10.0 mg/mL), indicating that the observed beta beta species are not artifacts due to intermolecular cross-linking. Upon denaturation and subsequent renaturation either by heating to 55 degrees C or by incubating at 45 degrees C followed by quenching to room temperature, or by guanidine hydrochloride exposure followed by phased renaturation by dialysis, the fraction of beta beta increases, indicating that the reassociation favors homodimer formation somewhat over random association. This result differs from the random association observed when the sulfhydryl on one of the chains is carboxyamidomethylated (Holtzer, M.E., Breiner, T., & Holtzer, A., 1984, Biopolymers 23, 1811-1833), and from the overwhelming heterodimer preferences reported for tropomyosins from other organisms (Lehrer, S.S., Qian, Y., & Hvidt, S., 1989, Science 246, 926-928; Lehrer, S.S. & Qian, Y., 1990, J. Biol. Chem. 265, 1134-1138).     

The effect of different ant species on the olive moth, Prays oleae (Bern.), in Spanish olive orchard

Abstract:  In the olive orchards of Granada, Spain, ants are one of the most abundant insect families. Two sites were compared in 1994 and 1995 – a commercial orchard and an abandoned one. In both, the temporal pattern of abundance and the ant species composition were similar. Drought affected captures between the years. The managed orchard had fewer species and was dominated by Tapinoma nigerrimum. Predation studies using enzyme-linked immunosorbent assay (ELISA) showed that the maximum number of ants found to be test positive for olive moth, Prays oleae remains coincided with the moth's most vulnerable period. In the commercial orchard the most abundant ant species also had, by far, the highest number of positives for predation whereas at the abandoned site several species were of equal importance. Trophallaxis and scavenging are two particular traits of ants that may artificially inflate the ELISA results. However, as a basis for further study, ELISA can greatly assist the identification of ant species which warrant further research into their possible role against the olive moth.     

Bacterially Induced Weathering of Ultramafic Rock and Its Implications for Phytoextraction

The bioavailability of metals in soil is often cited as a limiting factor of phytoextraction (or phytomining). Bacterial metabolites, such as organic acids, siderophores, or biosurfactants, have been shown to mobilize metals, and their use to improve metal extraction has been proposed. In this study, the weathering capacities of, and Ni mobilization by, bacterial strains were evaluated. Minimal medium containing ground ultramafic rock was inoculated with either of two Arthrobacter strains: LA44 (indole acetic acid [IAA] producer) or SBA82 (siderophore producer, PO₄ solubilizer, and IAA producer). Trace elements and organic compounds were determined in aliquots taken at different time intervals after inoculation. Trace metal fractionation was carried out on the remaining rock at the end of the experiment. The results suggest that the strains act upon different mineral phases. LA44 is a more efficient Ni mobilizer, apparently solubilizing Ni associated with Mn oxides, and this appeared to be related to oxalate production. SBA82 also leads to release of Ni and Mn, albeit to a much lower extent. In this case, the concurrent mobilization of Fe and Si indicates preferential weathering of Fe oxides and serpentine minerals, possibly related to the siderophore production capacity of the strain. The same bacterial strains were tested in a soil-plant system: the Ni hyperaccumulator Alyssum serpyllifolium subsp. malacitanum was grown in ultramafic soil in a rhizobox system and inoculated with each bacterial strain. At harvest, biomass production and shoot Ni concentrations were higher in plants from inoculated pots than from noninoculated pots. Ni yield was significantly enhanced in plants inoculated with LA44. These results suggest that Ni-mobilizing inoculants could be useful for improving Ni uptake by hyperaccumulator plants.     

Phycobilins of cryptophycean algae. Occurrence of dihydrobiliverdin and mesobiliverdin in cryptomonad biliproteins.

Structures of the open-chain tetrapyrrole (bilin) prosthetic groups of the cryptophycean biliproteins phycocyanin 645 (Cr-PC 645; from strain UW374), phycoerythrin 566 (Cr-PE 566; from strain Bermani) and phycoerythrin 545 (Cr-PE 545; from Proteomonas sulcata Hill & Wetherbee) were examined by absorption, 1H NMR spectroscopy, and mass spectrometry. These biliproteins carry the following covalently attached bilins: Cr-PC 645 (alpha subunit) has one mesobiliverdin, (beta subunit), two phycocyanobilins and a doubly linked 15,16-dihydrobiliverdin; Cr-PC 566 (alpha), bilin 584, (beta), phycoerythrobilin and two bilin 584 chromophores (Wedemayer, G.J., Wemmer, D.E., and Glazer, A.N. (1991) J. Biol. Chem. 266, 4731-4741); Cr-PE 545 (alpha) has one 15,16-dihydrobiliverdin and (beta), only phycoerythrobilins. This is the first report of naturally occurring biliproteins carrying either 15,16-dihydrobiliverdin or mesobiliverdin chromophores. Native cryptomonad phycobiliproteins have been classified on the basis of the position of their long wavelength absorption maxima. However, comparison of the bilins of Cr-PE 566 from strain Bermani with those of Cr-PE 566 of strain CBD shows that the two proteins carry different bilins on the alpha subunit. Consequently, the identity of the bilin prosthetic groups on cryptophycean phycobiliproteins cannot be unambiguously inferred from simple inspection of the visible absorption spectra.     

Transient expression of a p58 protein kinase cDNA enhances mammalian glycosyltransferase activity

The effect of expression of a p58 protein kinase on mammalian beta-1,4 galactosyltransferase enzyme activity was examined in vitro and in vivo. We found that p58 protein kinase expression enhanced galactosyltransferase enzyme activity approximately three-fold in vivo when compared to reporter gene activity. Galactosyltransferase enzyme activity was also substantially reduced in vitro when dephosphorylated, or when p58 specific antibodies were used to inhibit kinase activity. These results suggest that galactosyltransferase activity is influenced by phosphorylation, and that the p58 protein kinase may mediate this effect.