Ross Sea Mollusca from the Latitudinal Gradient Program: R/V Italica 2004 Rauschert dredge samples

Information regarding the molluscs in this dataset is based on the Rauschert dredge samples collected during the Latitudinal Gradient Program (LGP) on board the R/V “Italica” in the Ross Sea (Antarctica) in the austral summer 2004. A total of 18 epibenthic dredge deployments/samplings have been performed at four different locations at depths ranging from 84 to 515m by using a Rauschert dredge with a mesh size of 500μm. In total 8,359 specimens have been collected belonging to a total of 161 species. Considering this dataset in terms of occurrences, it corresponds to 505 discrete distributional records (incidence data). Of these, in order of abundance, 5,965 specimens were Gastropoda (accounting for 113 species), 1,323 were Bivalvia (accounting for 36 species), 949 were Aplacophora (accounting for 7 species), 74 specimens were Scaphopoda (3 species), 38 were Monoplacophora (1 species) and, finally, 10 specimens were Polyplacophora (1 species). This data set represents the first large-scale survey of benthic micro-molluscs for the area and provides important information about the distribution of several species, which have been seldom or never recorded before in the Ross Sea. All vouchers are permanently stored at the Italian National Antarctic Museum (MNA), Section of Genoa, enabling future comparison and crosschecking. This material is also currently under study, from a molecular point of view, by the barcoding project “BAMBi” (PNRA 2010/A1.10).     

Early Gag Immunodominance of the HIV-Specific T-Cell Response during Acute/Early Infection Is Associated with Higher CD8+ T-Cell Antiviral Activity and Correlates with Preservation of the CD4+ T-Cell Compartment

The important role of the CD8⁺ T-cell response on HIV control is well established. Moreover, the acute phase of infection represents a proper scenario to delineate the antiviral cellular functions that best correlate with control. Here, multiple functional aspects (specificity, ex vivo viral inhibitory activity [VIA] and polyfunctionality) of the HIV-specific CD8⁺ T-cell subset arising early after infection, and their association with disease progression markers, were examined. Blood samples from 44 subjects recruited within 6 months from infection (primary HIV infection [PHI] group), 16 chronically infected subjects, 11 elite controllers (EC), and 10 healthy donors were obtained. Results indicated that, although Nef dominated the anti-HIV response during acute/early infection, a higher proportion of early anti-Gag T cells correlated with delayed progression. Polyfunctional HIV-specific CD8⁺ T cells were detected at early time points but did not associate with virus control. Conversely, higher CD4⁺ T-cell set points were observed in PHI subjects with higher HIV-specific CD8⁺ T-cell VIA at baseline. Importantly, VIA levels correlated with the magnitude of the anti-Gag cellular response. The advantage of Gag-specific cells may result from their enhanced ability to mediate lysis of infected cells (evidenced by a higher capacity to degranulate and to mediate VIA) and to simultaneously produce IFN-γ. Finally, Gag immunodominance was associated with elevated plasma levels of interleukin 2 (IL-2) and macrophage inflammatory protein 1β (MIP-1β). All together, this study underscores the importance of CD8⁺ T-cell specificity in the improved control of disease progression, which was related to the capacity of Gag-specific cells to mediate both lytic and nonlytic antiviral mechanisms at early time points postinfection.     

Mechanism of activation of the Drosophila EGF Receptor by the TGFalpha ligand Gurken during oogenesis.

We have analyzed the mechanism of activation of the Epidermal growth factor receptor (Egfr) by the transforming growth factor (TGF) alpha-like molecule, Gurken (Grk). Grk is expressed in the oocyte and activates the Egfr in the surrounding follicle cells during oogenesis. We show that expression of either a membrane bound form of Grk (mbGrk), or a secreted form of Grk (secGrk), in either the follicle cells or in the germline, activates the Egfr. In tissue culture cells, both forms can bind to the Egfr; however, only the soluble form can trigger Egfr signaling, which is consistent with the observed cleavage of Grk in vivo. We find that the two transmembrane proteins Star and Brho potentiate the activity of mbGrk. These two proteins collaborate to promote an activating proteolytic cleavage and release of Grk. After cleavage, the extracellular domain of Grk is secreted from the oocyte to activate the Egfr in the follicular epithelium.     

Effects of nutrient and temperature on degradation of petroleum hydrocarbons in sub-Antarctic coastal seawater

In an attempt to evaluate the potential of petroleum bioremediation at high latitudes environments, microcosm studies using Antarctic coastal seawater contaminated with diesel or crude oil were conducted in Kerguelen Archipelago (49°22′S, 70°12′E). Microcosms were incubated at three different temperatures (4, 10 and 20°C). During experiments, changes observed in microbial assemblages (total direct count, heterotrophic cultivable microorganisms and hydrocarbon-degrading microorganisms) were generally similar for all incubation temperatures, but chemical data showed only some slight changes in biodegradation indices [Σ(C12–C20)/Σ(C21–C32) and C17/pristane]. The complete data set provided strong evidence of the presence of indigenous hydrocarbon-degrading bacteria in Antarctic seawater and their high potential for hydrocarbon bioremediation. The rate of oil degradation could be increased by the addition of a commercial fertilizer, but water temperature had little effects on biodegradation efficiency which is in conflict with the typical temperature-related assumption predicting 50% rate reduction when temperature is reduced by 10°C. Global warming of Antarctic seawater should not increase significantly the rate of oil biodegradation in these remote regions.     

Reduced expression of selected FASCICLIN‐LIKE ARABINOGALACTAN PROTEIN genes associates with the abortion of kernels in field crops of Zea mays (maize) and of Arabidopsis seeds

Abortion of fertilized ovaries at the tip of the ear can generate significant yield losses in maize crops. To investigate the mechanisms involved in this process, 2 maize hybrids were grown in field crops at 2 sowing densities and under 3 irrigation regimes (well‐watered control, drought before pollination, and drought during pollination), in all possible combinations. Samples of ear tips were taken 2–6 days after synchronous hand pollination and used for the analysis of gene expression and sugars. Glucose and fructose levels increased in kernels with high abortion risk. Several FASCICLIN‐LIKE ARABINOGALACTAN PROTEIN (FLA) genes showed negative correlation with abortion. The expression of ZmFLA7 responded to drought only at the tip of the ear. The abundance of arabinogalactan protein (AGP) glycan epitopes decreased with drought and pharmacological treatments that reduce AGP activity enhanced the abortion of fertilized ovaries. Drought also reduced the expression of AthFLA9 in the siliques of Arabidopsis thaliana. Gain‐ and loss‐of‐function mutants of Arabidopsis showed a negative correlation between AthFLA9 and seed abortion. On the basis of gene expression patterns, pharmacological, and genetic evidence, we propose that stress‐induced reductions in the expression of selected FLA genes enhance abortion of fertilized ovaries in maize and Arabidopsis.     

The stimulus-secretion coupling of glucose-induced insulin release. LIII. Calcium-dependency of the cyclic AMP response to nutrient secretagogues

Above a threshold value in excess of 5.6 mM, D-glucose increases the amount of cyclic AMP measured by radioimmunoassay in pancreatic rat islets and their surrounding incubation medium. As judged from the cyclic AMP content of islets exposed to isobutylmethylxanthine (1.0 mM), the glucose-induced increment in the rate of cyclic AMP generation represents a rapid and sustained phenomenon. The stimulant action of glucose on cyclic AMP accumulation is mimicked by L-leucine, and L-glutamine, these amino acids acting synergistically of one another. Trifluoperazine slightly decreases but fails to abolish the effect of glucose. In the absence of extracellular Ca2+, however, the cyclic AMP response to D-glucose, L-leucine and/or L-glutamine is severely impaired. These findings are compatible with the view that an increase in the generation rate of cyclic AMP participates in the process of nutrient-stimulated insulin release. This increase could be secondary to the nutrient-induced accumulation of Ca2+ in the islet cells leading to activation of adenylate cyclase by calmodulin.     

Identification of amidated forms of GLP-1 in rat tissues using a highly sensitive radioimmunoassay

The development of a sensitive radioimmunoassay (RIA) for C-terminally amidated forms of glucagon-like peptide-1 (GLP-1) is described. Rabbits immunized with GLP-1(7–36)amide conjugated to bovine serum albumin with glutaraldehyde produced antisera containing high-affinity antibodies directed against an epitope that included the free amidated C-terminus of the peptide. These antisera could be used in a sensitive RIA (detection limit 0.1 fmol/tube) that measured GLP-1(7–36)amide and GLP-1(1–36)amide equally. Total concentrations of amidated GLP-1 immunoreactivity in extracts of rat hypothalamus, pancreas and intestine were determined by RIA, and resolved into GLP-1(7–36)amide, GLP-1(1–36)amide and unidentified cross-reacting substances by HPLC. Whereas only GLP-1(7–36)amide could be identified in the hypothalamus, in amounts that represented 55–94% of total glucagon-like immunoreactivity (GLI), the pancreas produced chiefly GLP-1(1–36)amide, representing 0.8–3.4% of total GLI, and only trace or undetectable amounts of GLP-1(7–36)amide (0–0.36% of total GLI). This argues against any role of intrapancreatic GLP-1(7–36)amide in the secretion of insulin. In the terminal ileum total amidated GLP-1 immunoreactivity represented 27–73% of total GLI, and in five of six specimens only GLP-1(7–36)amide could be identified on HPLC, in amounts representing 13–17% of total GLI. Only one specimen of terminal ileum contained HPLC-identified GLP-1(1–36)amide (13% of total GLI) in addition to GLP-1(7–36)amide (31% of total GLI). Acid–ethanol extraction of peptide-free rat plasma with added GLP-1(7–36)amide gave recoveries of 91±SEM 2% in the range 20–200 pmol/l. Basal plasma amidated GLP-1 in six unanaesthetized rats was 4.1±1.1 pmol/l and rose to a maximum of 15.4±3.0 pmol/l 10 min after intragastric glucose 1 g/kg, illustrating the modest level of plasma responses of amidated forms of GLP-1.     

Genome sequence of the marine bacterium Marinobacter hydrocarbonoclasticus SP17, which forms biofilms on hydrophobic organic compounds

Marinobacter hydrocarbonoclasticus SP17 forms biofilms specifically at the interface between water and hydrophobic organic compounds (HOCs) that are used as carbon and energy sources. Biofilm formation at the HOC-water interface has been recognized as a strategy to overcome the low availability of these nearly water-insoluble substrates. Here, we present the genome sequence of SP17, which could provide further insights into the mechanisms of enhancement of HOCs assimilation through biofilm formation.