The spatial and vertical distribution of living (stained) benthic foraminifera from a tropical,intertidal environment,north Queensland,Australia

We investigated the distribution of living (stained) benthic foraminifera across a tropical, intertidal shoreline adjacent to Cocoa Creek, Queensland, Australia for the purpose of better understanding the nature of test production and ultimately fossil assemblage development within such environments. Short cores (up to 1 m) were collected during the wet and dry season, along an elevational gradient comprising non-vegetated intertidal mudflat and higher-intertidal mangrove forest environments. The distribution of stained specimens can be broadly delineated into assemblages characterising ‘upper mangrove’ (2.64–2.91 m above Lowest Astronomical Tide (LAT)) and ‘low mangrove-mudflat’ (1.62–2.18 m above LAT) environments. Agglutinated species were generally limited to upper mangrove stations. Calcareous species occurred within all of the intertidal environments examined but differ in their composition between upper and lower intertidal settings. Upper mangrove faunas were characterised by the agglutinated species Arenoparrella mexicana, Haplophragmoides wilberti, Miliammina fusca, Miliammina obliqua and Trochammina inflata and the calcareous species Helenina anderseni. Live (stained) assemblages at lower intertidal elevations were dominated by the calcareous species Ammonia aoteana, as well as Rosalina spp., Elphidium oceanicum, Triloculina oblonga, Ammonia pustulosa and Shackoinella globosa.     

Sm25, a major schistosome tegumental glycoprotein, is dependent on palmitic acid for membrane attachment.

Sm25, a major antigen in the surface tegument of the parasitic helminth Schistosoma mansoni, is a 25 kDa N-glycosylated glycoprotein which co-purifies with isolated surface membranes and behaves as an integral membrane protein in Triton X-114 (TX-114). The deduced amino acid sequence of Sm25 shows a short C-terminal hydrophobic domain between residues 163 and 180, containing six uncharged polar amino acids and followed by a Lys181-Ser192 dipeptide. We were interested in whether or not this marginal C-terminal amphiphilic domain is responsible for the association of Sm25 with the membrane or whether a post-translational modification such as the addition of glycosyl phosphatidyl inositol (GPI) represents the membrane anchor for this molecule. We find that treatment with phosphatidyl inositol-specific phospholipase C, which cleaves many GPI anchors, does not reveal Cross Reacting Determinant (CRD) on Sm25, nor affect the association of this protein with membranes, providing no support for the addition of GPI. However, Sm25 is palmitoylated via a thioester bond to the single Cys residue, at position 168, which lies within the C-terminal hydrophobic domain. Removal of palmitate by reduction results in a marked decrease in the hydrophobicity of Sm25, as demonstrated by its partitioning into the aqueous rather than detergent phase of TX-114 and its quantitative release from membrane preparations. The hydrophobicity of several membrane proteins in addition to Sm25 is also decreased by reduction, raising the possibility that fatty acylation by thioester linkage is an important mechanism used by schistosomes to stabilize protein-membrane interactions.     

Schistosoma mansoni: antigen preparations which induce antibodies to schistosomula surface antigens

To determine the easiest method of raising antibodies to antigens exposed on the surface of schistosomula of Schistosoma mansoni, several crude preparations of the parasite were used to immunize mice. Schistosomula released products, whole worm homogenate, and parasite eggs all raised antibodies which bound to the surface of live schistosomula, although the anti-egg antiserum did so less strongly. Anti-schistosomula released products antiserum recognized three schistosomula surface antigens of Mr 15,000, 20,000, and 32,000, anti-whole worm homogenate recognized 20,000, 32,000, and 38,000 Mr surface antigens, and anti-egg recognized a less than 200,000 Mr surface antigen. None of these antigens was recognized when the labeled preparation was immunoprecipitated with its homologous antiserum. When these antisera were used to immunoprecipitate cell free translation products of adult worm RNA, the antischistosomula released products and anti-whole worm homogenate recognized an 11,000 Mr doublet while the anti-egg precipitated 14,000 and 44,000 Mr antigens. Other crude preparations were used to immunize rabbits; Formalin-fixed schistosomula, denuded adult worms, and purified worm tegument all induced antibodies which recognized the 20,000, 32,000, and 38,000 Mr schistosomula surface antigens.     

The influence of sea level and cyclones on Holocene reef flat development: Middle Island,central Great Barrier Reef

The geomorphology and chronostratigraphy of the reef flat (including microatoll ages and elevations) were investigated to better understand the long-term development of the reef at Middle Island, inshore central Great Barrier Reef. Eleven cores across the fringing reef captured reef initiation, framework accretion and matrix sediments, allowing a comprehensive appreciation of reef development. Precise uranium–thorium ages obtained from coral skeletons revealed that the reef initiated ~7873 ± 17 years before present (yBP), and most of the reef was emplaced in the following 1000 yr. Average rates of vertical reef accretion ranged between 3.5 and 7.6 mm yr^?1. Reef framework was dominated by branching corals (Acropora and Montipora). An age hiatus of ~5000 yr between 6439 ± 19 and 1617 ± 10 yBP was observed in the core data and attributed to stripping of the reef structure by intense cyclones during the mid- to late-Holocene. Large shingle ridges deposited onshore and basset edges preserved on the reef flat document the influence of cyclones at Middle Island and represent potential sinks for much of the stripped material. Stripping of the upper reef structure around the outer margin of the reef flat by cyclones created accommodation space for a thin (<1.2 m) veneer of reef growth after 1617 ± 10 yBP that grew over the eroded mid-Holocene reef structure. Although limited fetch and open-water exposure might suggest the reef flat at Middle Island is quite protected, our results show that high-energy waves presumably generated by cyclones have significantly influenced both Holocene reef growth and contemporary reef flat geomorphology.     

Three reasons protein disorder analysis makes more sense in the light of collagen

We have identified that the collagen helix has the potential to be disruptive to analyses of intrinsically disordered proteins. The collagen helix is an extended fibrous structure that is both promiscuous and repetitive. Whilst its sequence is predicted to be disordered, this type of protein structure is not typically considered as intrinsic disorder. Here, we show that collagen‐encoding proteins skew the distribution of exon lengths in genes. We find that previous results, demonstrating that exons encoding disordered regions are more likely to be symmetric, are due to the abundance of the collagen helix. Other related results, showing increased levels of alternative splicing in disorder‐encoding exons, still hold after considering collagen‐containing proteins. Aside from analyses of exons, we find that the set of proteins that contain collagen significantly alters the amino acid composition of regions predicted as disordered. We conclude that research in this area should be conducted in the light of the collagen helix.     

Hypoxanthine phosphoribosyltransferase from human brain: purification and partial characterization

A facile and rapid purification procedure, based upon the heat denaturation of extraneous proteins and GMP-Sepharose affinity chromatography, has been used to purify hypoxanthine phosphoribosyltransferase from human brain. A homogeneous enzyme preparation, as judged by sodium dodecyl sulfate and gradient polyacrylamide gel electrophoresis, was obtained. The subunit molecular weight of the enzyme was estimated as 24,000 by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The native molecular weight, determined by gradient gel electrophoresis, was approximately 100,000. These results suggest human brain hypoxanthine phosphoribosyltransferase is a tetramer, consistent with recent results reported for the human erythrocyte enzyme. At least three charge variant forms of the human brain enzyme were distinguished by nondenaturing polyacrylamide gel electrophoresis, electrofocusing, and chromatofocusing. Acidic pI values of approximately 5.7, 5.5, and 5.0 were estimated for the three major species.