bluuebunny/crossref_metadata_2025 huggingface dataset:
Live‐cell analysis of cell penetration ability and toxicity of oligo‐arginines
Authors: Tünnemann Gisela , Ter‐Avetisyan Gohar , Martin Robert M. , Stöckl Martin , Herrmann Andreas , Cardoso M. Cristina
Published: December 2007

Cell penetrating peptides (CPPs) are useful tools to deliver low‐molecular‐weight cargoes into cells; however, their mode of uptake is still controversial. The most efficient CPPs belong to the group of arginine‐rich peptides, but a systematic assessment of their potential toxicity is lacking. In this study we combined data on the membrane translocation abilities of oligo‐arginines in living cells as a function of their chain length, concentration, stability and toxicity. Using confocal microscopy analysis of living cells we evaluated the transduction frequency of the L‐isoforms of oligo‐arginines and lysines and then monitored their associated toxicity by concomitant addition of propidium iodide. Whereas lysines showed virtually no transduction, the transduction ability of arginines increased with the number of consecutive residues and the peptide concentration, with L‐R9 and L‐R10 performing overall best. We further compared the L‐ and D‐R9 isomers and found that the D‐isoform always showed a higher transduction as compared to the L‐counterpart in all cell types. Notably, the transduction difference between D‐ and L‐forms was highly variable between cell types, emphasizing the need for protease‐resistant peptides as vectors for drug delivery. Real‐time kinetic analysis of the D‐ and L‐isomers applied simultaneously to the cells revealed a much faster transduction for the D‐variant. The latter underlies the fact that the isomers do not mix, and penetration of one peptide does not perturb the membrane in a way that gives access to the other peptide. Finally, we performed short‐ and long‐term cell viability and cell cycle progression analyses with the protease‐resistant D‐R9. Altogether, our results identified concentration windows with low toxicity and high transduction efficiency, resulting in fully bioavailable intracellular peptides. Copyright © 2007 European Peptide Society and John Wiley & Sons, Ltd.
Membrane‐bound peptides from V‐ATPase subunit a do not interact with an indole‐type inhibitor
Authors: Hesselink Renske W. , Fedorov Alexander , Hemminga Marcus A. , Prieto Manuel
Published: December 2007

The V‐ATPases are ATP‐dependent proton pumps, found in virtually all cells, responsible for acidification of organelles and energizing of plasma membranes. Its role in diseases, such as osteoporosis and metastatic cancer, makes the V‐ATPase a potential drug target. Short synthetic peptides that are presented here mimic the 7th transmembrane domain (TM7) of subunit a (Vph1p) of Saccharomyces cerevisiae V‐ATPase, an essential part of the membrane‐bound VO domain, where proton translocation takes place. The peptides adopt a transmembrane configuration only in membranes containing anionic lipids, stressing the importance of strong interfacial anchoring by the flanking lysines. Peptide P1, which contains the essential arginine R735, is monomeric, whereas peptide P2, which lacks this extra charge, tends to aggregate in the membrane. SB 242784, which is a highly potent inhibitor of V‐ATPase, does not show any interaction with the peptides, indicating that TM7 alone is not sufficient for inhibitor binding. Copyright © 2007 European Peptide Society and John Wiley & Sons, Ltd.
Mass spectrometric characterization of β‐caryophyllene ozonolysis products in the aerosol studied using an electrospray triple quadrupole and time‐of‐flight analyzer hybrid system and density functional theory
Authors: Kanawati Basem , Herrmann Frank , Joniec Seweryn , Winterhalter Richard , Moortgat Geert K.
Published: December 2007

The components of the organic aerosol formed due to gas‐phase β‐caryophyllene ozonolysis were characterized by the use of a triple quadrupole and time‐of‐flight analyzer hybrid system coupled to an electrospray ionization source operated in the negative ion mode. A reversed‐phase high‐performance liquid chromatography (HPLC) column was used to achieve chromatographic separations at neutral pH which has been proved to induce ionization of organic compounds bearing aldehyde moieties. In addition to the detected oxo‐ and dicarboxylic acids, isomeric oxidation products, which bear multi‐functional groups such as aldehyde, carbonyl and hydroxyl groups, could be differentiated by examining their corresponding collision‐induced dissociation (CID) fragmentation pathways. Proposed fragmentation mechanisms were drawn for the experimentally observed fragmentation pathways in all the CID experiments. Cyclic oxidation products could also be discerned and their fragmentation behaviour under low energy collsional conditions was studied in detail. Gas‐phase deprotonation potentials were calculated by the use of DFT B3LYP/6‐311+G(2d,p)//B3LYP/6‐31+G(d) + ZPVE to estimate the most thermodynamically favourable deprotonation site for efficient negative ion formation in the ion source. The optimized gas‐phase geometries for the most prominent oxidation products reveal a strong intramolecular interaction between the upper and lower C4 carbon chains, which are formed after the decomposition of the primary ozonide generated by ozone attack of the reactive endocyclic CC bond. Copyright © 2007 John Wiley & Sons, Ltd.
Confidence intervals for the risk ratio under inverse sampling
Authors: Tian M. , Tang M. L. , Ng H. K. T. , Chan P. S.
Published: December 2007

In this paper, we investigate various confidence intervals for the risk ratio under inverse sampling (also known as negative binomial sampling). Three existing confidence intervals (namely, the confidence intervals that are based on Fieller's theorem, the delta method and theF‐statistic) are reviewed and three new confidence intervals (namely, the score, likelihood ratio and saddlepoint approximation (SA)‐based confidence intervals) are developed. Comparative studies among these confidence intervals through Monte Carlo simulations are evaluated in terms of their coverage probabilities and expected interval widths under different settings. Our simulation results suggest that the SA‐based confidence interval is generally more appealing. We illustrate these confidence interval construction methods with real data sets from a drug comparison study and a congenital heart disease study. Copyright © 2007 John Wiley & Sons, Ltd.
Investigating trial and treatment heterogeneity in an individual patient data meta‐analysis of survival data by means of the penalized maximum likelihood approach
Authors: Rondeau V. , Michiels S. , Liquet B. , Pignon J. P.
Published: December 2007

In a meta‐analysis combining survival data from different clinical trials, an important issue is the possible heterogeneity between trials. Such intertrial variation can not only be explained by heterogeneity of treatment effects across trials but also by heterogeneity of their baseline risk. In addition, one might examine the relationship between magnitude of the treatment effect and the underlying risk of the patients in the different trials. Such a scenario can be accounted for by using additive random effects in the Cox model, with a random trial effect and a random treatment‐by‐trial interaction. We propose to use this kind of model with a general correlation structure for the random effects and to estimate parameters and hazard function using a semi‐parametric penalized marginal likelihood method (maximum penalized likelihood estimators). This approach gives smoothed estimates of the hazard function, which represents incidence in epidemiology. The idea for the approach in this paper comes from the study of heterogeneity in a large meta‐analysis of randomized trials in patients with head and neck cancers (meta‐analysis of chemotherapy in head and neck cancers) and the effect of adding chemotherapy to locoregional treatment. The simulation study and the application demonstrate that the proposed approach yields satisfactory results and they illustrate the need to use a flexible variance–covariance structure for the random effects. Copyright © 2007 John Wiley & Sons, Ltd.
Meta‐analysis of continuous outcomes combining individual patient data and aggregate data
Authors: Riley Richard D. , Lambert Paul C. , Staessen Jan A. , Wang Jiguang , Gueyffier Francois , Thijs Lutgarde , Boutitie Florent
Published: December 2007

Meta‐analysis of individual patient data (IPD) is the gold‐standard for synthesizing evidence across clinical studies. However, for some studies IPD may not be available and only aggregate data (AD), such as a treatment effect estimate and its standard error, may be obtained. In this situation, methods for combining IPD and AD are important to utilize all the available evidence. In this paper, we develop and assess a range of statistical methods for combining IPD and AD in meta‐analysis of continuous outcomes from randomized controlled trials.

The methods take either a one‐step or a two‐step approach. The latter is simple, with IPD reduced to AD so that standard AD meta‐analysis techniques can be employed. The one‐step approach is more complex but offers a flexible framework to include both patient‐level and trial‐level parameters. It uses a dummy variable to distinguish IPD trials from AD trials and to constrain which parameters the AD trials estimate. We show that this is important when assessing how patient‐level covariates modify treatment effect, as aggregate‐level relationships across trials are subject to ecological bias and confounding. We thus develop models to separate within‐trial and across‐trials treatment–covariate interactions; this ensures that only IPD trials estimate the former, whilst both IPD and AD trials estimate the latter in addition to the pooled treatment effect and any between‐study heterogeneity. Extension to multiple correlated outcomes is also considered. Ten IPD trials in hypertension, with blood pressure the continuous outcome of interest, are used to assess the models and identify the benefits of utilizing AD alongside IPD. Copyright © 2007 John Wiley & Sons, Ltd.
Timing of lung size assessment in the prediction of survival in fetuses with diaphragmatic hernia
Authors: Jani J. , Nicolaides K. H. , Benachi A. , Moreno O. , Favre R. , Gratacos E. , Deprest J.
Published: December 2007

Objectives

To investigate whether the prediction of postnatal outcome of fetuses with isolated congenital diaphragmatic hernia depends on the gestational age at assessment using the fetal observed to expected (O/E) lung area to head circumference ratio (LHR), by comparing the performance of the test at 22–23 weeks with that at 32–33 weeks of gestation.

Methods

Following prenatal diagnosis of isolated diaphragmatic hernia before 22 weeks, we evaluated the O/E LHR at 22–32 weeks and again at 32–33 weeks of gestation. Only cases liveborn beyond 34 weeks of gestation and with postnatal follow‐up available until discharge from the hospital were included. Regression analysis was used to examine the effect on postnatal survival of O/E LHR, gestational age at delivery, side of the diaphragmatic hernia and intrathoracic position of the liver. Wilcoxon rank test for paired samples was used to compare median O/E LHR at 22–23 weeks and 32–33 weeks, in babies who survived and in those who died. Receiver–operating characteristics (ROC) curves were constructed for the prediction of survival by O/E LHR at 22–23 weeks and at 32–33 weeks.

Results

In total, 53 pairs of measurements could be assessed. Univariate logistic regression analysis demonstrated that significant predictors of survival were the presence or absence of intrathoracic herniation of the liver, the O/E LHR at 22–23 weeks and the O/E LHR at 32–33 weeks of gestation. Multivariate logistic regression analysis demonstrated that only O/E LHR at 22–23 weeks or 32–33 weeks provided significant independent prediction of survival. The median O/E LHR at 22–23 weeks was not significantly different from that at 32–23 weeks either in survivors or in babies that subsequently died in the neonatal period (P = 0.25 and P = 0.09, respectively). The area under the ROC curve for prediction of postnatal survival from the O/E LHR at 22–23 weeks was 0.789 (P < 0.001) and that for prediction from the O/E LHR at 32–33 weeks was 0.842 (P < 0.001).

Conclusions

In isolated diaphragmatic hernia, O/E LHR measurement at 22–23 weeks as well as at 32–33 weeks provides useful independent prediction of subsequent survival. The prediction of postnatal survival using O/E LHR is independent of the timing of assessment. Copyright © 2007 ISUOG. Published by John Wiley & Sons, Ltd.
Diagenesis evaluation in Middle Ages human bones using EDXRF
Authors: Carvalho M. L. , Marques A. F.
Published: December 2007

The elemental concentration in buried human bones is studied by energy dispersive x‐ray fluorescence. Several cortical and trabecular bones: skulls, peroneus, mandibles, tibias, femurs, ribs, vertebras and omoplates, belonging to a population dating to the Middle Ages were analysed. The purpose of this study is to compare the behaviour of the different structures of the several bones during the diagenetic process affecting bone during burial. Quantitative analysis was performed for K, Ca, Zn, Sr, Ti, Mn, Fe and Pb and cluster analysis was achieved considering the elemental concentrations for the different bones. There is a clear distinction for bone association regarding Ca, Zn, Sr and K, Mn, Fe, Ti and Pb in the several bones. These results do not allow a clear categorization into cortical and trabecular bones for some of the samples studied, as far as distinguishing between the remains of the original bone and the environmental contamination from the surrounding soil. Copyright © 2007 John Wiley & Sons, Ltd.
The certification of the Mondex electronic purse to ITSEC Level E6
Authors: Woodcock Jim , Stepney Susan , Cooper David , Clark John , Jacob Jeremy
Published: December 2007

Ten years ago the Mondex electronic purse was certified to ITSEC Level E6, the highest level of assurance for secure systems. This involved building formal models in the Z notation, linking them with refinement, and proving that they correctly implement the required security properties. The work has been revived recently as a pilot project for the international Grand Challenge in Verified Software. This paper records the history of the original project and gives an overview of the formal models and proofs used.
Modeling and validating Mondex scenarios described in UML and OCL with USE
Authors: Kuhlmann Mirco , Gogolla Martin
Published: December 2007

This paper describes the Mondex case study with UML class diagrams and restricting OCL constraints. The constraints have been formulated either as OCL class invariants or as OCL pre- and postconditions. The proposed two models include UML class diagrams and OCL constraints which have been checked by the UML and OCL tool USE (UML-based Specification Environment). USE allows validation of a model by testing it with scenarios. The Mondex case study has been validated by positive and negative test cases. The test cases allow the validity of the various constraints to be traced and checked. Validation results are presented as textual protocols or as UML sequence diagrams where starting, intermediate, and resulting system states are represented by UML object diagrams. UML sequence diagrams, UML object diagrams, and textual protocols are shown with varying degrees of detail for the attributes, constraints, and executed commands.
The Clinical Conundrum of Corticotropin‐independent Autonomous Cortisol Secretion in Patients with Bilateral Adrenal Masses
Authors: Young William F. , du Plessis Hendrick , Thompson Geoffrey B. , Grant Clive S. , Farley David R. , Richards Melanie L. , Erickson Dana , Vella Adrian , Stanson Anthony W. , Carney J. Aidan , Abboud Charles F. , Carpenter Paul C.
Published: December 2007

Background

Management of patients with bilateral adrenal masses and corticotropin (ACTH)‐independent Cushing syndrome (CS) or subclinical CS is problematic. We report our experience with adrenal venous sampling (AVS) in the evaluation of 10 patients with bilateral masses who had ACTH‐independent CS or subclinical CS.

Patients and Methods

Ten patients (9 women, 1 man, mean age 56.4 years) with bilateral adrenal masses and ACTH‐independent CS (n = 3) or subclinical CS (n = 7) underwent AVS. Autonomous cortisol secretion was documented in all cases with suppressed serum ACTH concentrations and lack of cortisol suppression with dexamethasone administration. Adrenal venous sampling was performed on the second day of dexamethasone administration. Cortisol and epinephrine levels were measured from each adrenal vein (AV) and from a peripheral vein (PV).

Results

Mean (± SD) maximal diameter of the adrenal masses on computed tomography was 3.3 ± 1.3 cm (range: 1.2–6.0 cm). Successful catheterization was confirmed with AV:PV epinephrine gradients. A cortisol AV:PV gradient >6.5 was consistent with a cortisol‐secreting adenoma in 11 adrenal glands; 5 patients had clinically important bilateral autonomous cortisol hypersecretion, 3 had bilateral cortisol‐secreting adenomas, and 2 had ACTH‐independent macronodular adrenal hyperplasia. Adrenal venous sampling‐guided adrenalectomy was completed in all 10 patients—2 patients had total bilateral adrenalectomy and 2 others had subtotal bilateral adrenalectomy. During a mean follow‐up of 36.1 months (range: 0.7–123 months), CS or clinically important cortisol secretory autonomy did not recur.

Conclusions

Adrenal venous sampling contributed to the localization of autonomous hypercortisolism in the setting of ACTH‐independent CS or subclinical CS in patients with bilateral adrenal masses.
Mathematical modeling of colony formation in algal blooms: phenotypic plasticity in cyanobacteria
Authors: Serizawa Hiroshi , Amemiya Takashi , Enomoto Takatoshi , Rossberg Axel G. , Itoh Kiminori
Published: December 2007

In this paper, we analyzed a mathematical model of algal‐grazer dynamics, including the effect of colony formation, which is an example of phenotypic plasticity. The model consists of three variables, which correspond to the biomasses of unicellular algae, colonial algae, and herbivorous zooplankton. Among these organisms, colonial algae are the main components of algal blooms. This aquatic system has two stable attractors, which can be identified as a zooplankton‐dominated (ZD) state and an algal‐dominated (AD) state, respectively. Assuming that the handling time of zooplankton on colonial algae increases with the colonial algae biomass, we discovered that bistability can occur within the model system. The applicability of alternative stable states in algae‐grazer dynamics as a framework for explaining the algal blooms in real lake ecosystems, thus, seems to depend on whether the assumption mentioned above is met in natural circumstances.
Short‐term variations in abundances and potential activities of viruses, bacteria and nanoprotists in Lake Bourget
Authors: Sime‐Ngando T. , Colombet J. , Personnic S. , Domaizon I. , Dorigo U. , Perney P. , Hustache J. C. , Viollier E. , Jacquet S.
Published: December 2007

Samples were collected at four depths every 6 h over a 42‐h period during two contrasting seasons (June vs. December) from Lake Bourget, France, for evidence of circadian fluctuations in the concentrations and potential activities of viruses, prokaryotes and protists in relation to environmental conditions: temperature, chlorophyll a and dissolved organic carbon (DOC) concentrations. Considerable vertical and temporal fluctuations were observed for all variables. Circadian variations were noted for DOC and chlorophyll a concentrations. Despite the external abiotic forcing (light, water movements), the fluctuations of microbial variables (including viruses) in most cases were apparently linked to biotic factors and interactions. Standing stocks and activities, as well as the number and levels of correlations among the microbial components, were, surprisingly, higher in winter than in summer. We speculate that this was because trophic interactions prevailed over the seasonal forcing (i.e. temperature) in shaping the observed differences.
Indonesian women and political Islam
Authors: Blackburn Susan
Published: December 2007

This article investigates the history of women's relationship to political Islam in Indonesia over the last century. It addresses three questions: how Islamic women have been politically active in Indonesia, how Indonesian women have been affected by political Islam, and how they have influenced political Islam. Independence marked a turning point. In the colonial period, women were more active within radical Islamic organisations than in moderate ones. Since independence, however, the situation has changed. Instead, the role of women has strengthened in moderate organisations while radical Islam has kept women in the background.
Southern elephant seal movements and Antarctic sea ice
Authors: Bornemann H. , Kreyscher M. , Ramdohr S. , Martin T. , Carlini A. , Sellmann L. , Plötz J.
Published: December 2007

Weaned pups and post-moult female elephant seals (Mirounga leonina) were fitted with satellite transmitters at King George Island (South Shetland Islands) between December 1996 and February 1997. Of the nine adult females tracked for more than two months, three stayed in a localized area between the South Shetland Islands and the South Orkney Islands. The other six females travelled south-west along the coast of the Antarctic Peninsula up to the Bellingshausen Sea. Two of them then moved north-east and hauled out on South Georgia in October. One female was last located north of the South Shetland Islands in March 1998. In total, eight females were again sighted on King George Island and six of the transmitters removed. The tracks of the weaners contrasted with those of the adults. In January, five juveniles left King George Island for the Pacific sector spending about four weeks in the open sea west of the De Gerlache Seamounts. Three of them returned to the tip of the Antarctic Peninsula in June, of which one was last located on the Patagonian Shelf in November 1997. The juveniles avoided sea ice while the adults did not. The latter displayed behavioural differences in using the pack ice habitat during winter. Some females adjusted their movement patterns to the pulsating sea ice fringe in distant foraging areas while others ranged in closed pack ice of up to 100%. The feeding grounds of adult female elephant seals are more closely associated with the pack ice zone than previously assumed. The significance of the midwater fish Pleuragramma antarcticum as a potential food resource is discussed.
Cephalopod diet of the southern elephant seal, Mirounga leonina, at King George Island, South Shetland Islands
Authors: Daneri G.A. , Carlini A.R. , Rodhouse P.G.K.
Published: December 2007

In the summer of 1995/96, 25 southern elephant seals, Mirounga leonina, were stomach lavaged at Stranger Point, King George Island, South Shetland Islands. Cephalopod remains were present in 72% of the individuals sampled (n = 18). Seven species of squid and three of octopus were identified. The squid Psychroteuthis glacialis was the most important prey in terms of numbers (77%), biomass (80.8%) and frequency of occurrence (94.4%). Next in importance in terms of mass was the squid Alluroteuthis antarcticus (7.8%) in the diet of females and the octopodid Pareledone ?charcoti in the diet of males (13.2%). Females preyed on a wider variety of squid taxa than males (7 vs 3) but octopodids occurred only in stomach contents from males. The predominance of P. glacialis in the prey of the South Shetland Islands elephant seals can be explained by the southerly location of the foraging areas of this population compared to South Georgia, Heard and Macquarie islands, where the diet of southern elephant seals has previously been analysed. Psychroteuthis glacialis is the predominant squid in waters close to the Antarctic continent.
Graneledone gonzalezi sp. nov. (Mollusca: Cephalopoda): a new octopod from the Îles Kerguelen
Authors: Guerra Angel , González Angel F. , Cherel Yves
Published: December 2007

A new octopod species, Graneledone gonzalezi sp. nov., is described from 19 specimens collected off the northern Îles Kerguelen. This is a bathyal octopus which is characterized by: the absence of supra-ocular papillae, short arms, a long ligula without copulatory ridges, a narrow head, six filaments per outer demibranch and radula exhibiting no archaic traits, medium size oocytes and a low number of very long spermatophores. Graneledone gonzalezi is compared with its other congeneric species and found most closely resemble G. antarctica. The geographic and bathymetric distribution of G. gonzalezi is also discussed.
Predator–prey relationship between the nototheniid fish Trematomus bernacchii and the Antarctic scallop Adamussium colbecki at Terra Nova Bay (Ross Sea)
Authors: Vacchi Marino , Cattaneo-Vietti R. , Chiantore M. , Dalu M.
Published: December 2007

Little information is available regarding predator-prey interactions in High-Antarctic coastal systems. In this study, the predation of Trematomus bernacchii (Pisces: Nototheniidae) on Adamussium colbecki (Mollusca: Pectinidae) is described and the related impact on the population structure of the mollusc is hypothesized. Fishes and scallops were collected during several expeditions between 1990/91 and 1997/98 summers, in nearshore waters at Terra Nova Bay (Antarctica). Adamussium colbecki was the main food item of T. bernacchii and an ontogenetic prey-size selection was observed. The predation was mainly on medium size classes of the scallop. These were lacking in the A. colbecki population sampled in the same period suggesting that the impact of fish-feeding on the size structure of the natural population of the mollusc may be substantial. Two size classes of the Adamussium population were not preyed on. Large adults avoid predation either because of the limits for mouth gape in the fish or by swimming avoidance capability, while smaller scallops may not be preyed upon because they are attached through byssus threads to very mobile large adults.
Late Holocene increase in sea ice extent in fjords of the Vestfold Hills, eastern Antarctica
Authors: McMinn Andrew
Published: December 2007

Sediment cores from Abel and Platcha Bays, in the Vestfold Hills, east Antarctica, contain evidence for a local late Holocene increase in fast ice extent and a possible ice cap retreat at approximately 1750 yr BP, a similar time to the Chelnock Glaciation. Prior to this time both bays experienced periods of isolation that lead to changes in their diatom flora, C:N ratio, percentage of biogenic silica and total organic carbon. Three new diatom indices are proposed; the fast ice index, based on the proportion of fast ice taxa present, the benthic index, based on the proportion of benthic taxa and the snow index, based on the proportion Berkelaya adeliense and Thalassiosira ausiralis. These indices show strong relationships with the percentage of biogenic silica, total organic carbon and percentage sand. A weak relationship exists between the fast ice index and ∂13C and no relationship with the C:N ratio.
The effect of ocean tidal loading on satellite altimetry over Antarctica
Authors: Yi Donghui , Minster J. Bernard , Bentley Charles R.
Published: December 2007

Vertical displacements of emerged land caused by oceanic tidal loading are of the order of several tens of millimetres in polar regions. They constitute a long wavelength signal, the amplitude of which is comparable to elevation changes that might be associated with climate-driven changes in ice-sheet volume. Using bilinear interpolation on a 1° by 1° global grid, we examine the amplitudes and phases of vertical displacements caused at any given epoch by the eight most important ocean tide constituents of recent ocean tide models, extrapolated to high latitudes. This permits estimation of the oceanic tidal loading corrections to measurements made by a satellite altimeter along the satellite ground track. We have done so systematically over Antarctica, for a scenario flight of ICESAT, which carries the Geoscience Laser Altimeter System (GLAS), whose primary science goal is to monitor ice-sheet mass balance. Ocean loading tide corrections near the coast of Antarctica can reach several centimetres; overall they average about 10 min.
Selecting Antarctic Specially Protected Areas: Important Bird Areas can help
Authors: Cooper John , Woehler Eric , Belbin Lee
Published: December 2007

A key element in Antarctic conservation over the past forty years has been area protection. In pursuit of this and the protection of continuing scientific investigations 59 protected areas have so far been agreed by the Antarctic Treaty Consultative Meetings. Although both flora and fauna have been protected under this regime there has only been the habitat matrix devised by SCAR as a guide to selection of areas. What could we do to improve the process of identification and selection?
Sedimentology and geochemistry of a perennially ice-covered epishelf lake in Bunger Hills Oasis, East Antarctica
Authors: Doran Peter T. , Wharton R.A. , Lyons W.B. , Marais D.J. Des , Andersen D.T.
Published: December 2007

A process-oriented study was carried out in White Smoke lake, Bunger Hills, East Antarctica, a perennially ice-covered (1.8 to 2.8 m thick) epishelf (tidally-forced) lake. The lake water has a low conductivity and is relatively well mixed. Sediments are transferred from the adjacent glacier to the lake when glacier ice surrounding the sediment is sublimated at the surface and replaced by accumulating ice from below. The lake bottom at the west end of the lake is mostly rocky with a scant sediment cover. The east end contains a thick sediment profile. Grain size and δ13C increase with sediment depth, indicating a more proximal glacier in the past. Sedimentary 210Pb and 137Cs signals are exceptionally strong, probably a result of the focusing effect of the large glacial catchment area. The post-bomb and pre-bomb radiocarbon reservoirs are c. 725 14 C yr and c. 1950 14C yr, respectively. Radiocarbon dating indicates that the east end of the lake is >3 ka BP, while photographic evidence and the absence of sediment cover indicate that the west end has formed only over the last century. Our results indicate that the southern ice edge of Bunger Hills has been relatively stable with only minor fluctuations (on the scale of hundreds of metres) over the last 3000 years.
Weaning mass and the future survival of juvenile southern elephant seals, Mirounga leonina, at Macquarie Island
Authors: McMahon Clive R. , Burton Harry R. , Bester Marthán N.
Published: December 2007

Seals that survived their first year were on average 2% and 4% heavier at birth and at weaning than the “non-survivors”. First year survival rates calculated for weaners over 135 kg weaning masses showed these weaners had higher survival rates than those less than 95 kg at weaning (71.55% and 54.15% respectively). Heavy weaners had greater fat reserves than light weaners and gained relatively more mass during lactation. Size, and therefore condition at weaning, influences first year survival.
An initial palaeosalinity history of Jaw Lake, Bunger Hills based on a diatom–salinity transfer function applied to sediment cores
Authors: Roberts D. , McMinn A. , Zwartz D.
Published: December 2007

Two sediment cores taken from Jaw lake (Bunger Hills, East Antarctica) were analysed for diatom composition and abundance. A diatom-salinity transfer function developed for the nearby Vestfold Hills was used to determine palaeosalinity reconstructions from the assemblages preserved in each of the cores. There is a large step-wise decrease in salinity in the second core from at least c. 4000 to c. 2000 uncorrected 14C yr BP. The salinity record from the first core starts at c. 3000 uncorrected 14C yr BP and is comparable with the salinity of the second core between c. 3000 and c. 2000 uncorrected 14C yr BP. Sudden lake water dilution in both cores at c. 1900 uncorrected 14C yr BP is followed by brief increases in lake water salinity between c. 1900 and c. 500 uncorrected 14C yr BP, after which gradual dilution to present occurs. This analysis of the local environmental history of this saline lake reveals a mid–late Holocene evolution of the lake basin similar to that documented from earlier marine and freshwater lacustrine sediments in the Bunger Hills. The high coherence of the independent sediment records suggests a robust general palaeosalinity reconstruction of the lake is achieved in addition to providing evidence for the fidelity of single sediment cores as useful and adequate representation of the palaeolimnological histories of Antarctic lakes.
Sublithic bacteria associated with Antarctic quartz stones
Authors: Smith Matthew C. , Bowman John P. , Scott Fiona J. , Line Martin A.
Published: December 2007

Quartz stone sublithic cyanobacterial communities are common throughout the Vestfold Hills, Eastern Antarctica (68°S 78°E) contributing biomass in areas otherwise devoid of any type of vegetation. In this study, the sublithic microbial community and underlying soil was investigated using a variety of traditional and molecular methods. Although direct epifluorescent counts of the sublithic growth (average 1.1 × 109 cells g−1 dry weight) and underlying soil (0.5 × 109 cells g−1 dry weight) were similar, sublith viable counts (2.1 × 107 cfu g−1 dry weight) were on average 3-orders of magnitude higher in the subliths. Enrichment and molecular analyses revealed the predominate cyanobacteria were non-halophilic, able to grow optimally at 15–20°C, and were related to the Phormidium subgroup with several distinct morphotypes and phylotypes present. Sublithic heterotrophic bacterial populations and those of underlying soils included mostly psychrotolerant taxa typical of Antarctic soil. However, psychrophilic and halophilic bacteria, mostly members of the alpha subdivision of the Proteobacteria and the order Cytophagales, were abundant in the sublithic growth film (20–40% of the viable count and about 50% of isolated individual taxa) but absent from underlying soils. It is suggested that quartz stone subliths might constitute a “refuge” for psychrophilic bacteria.
A new macroflora from the South Orkney Islands, Antarctica: evidence of an Early to Middle Jurassic age for the Powell Island Conglomerate
Authors: Cantrill David J.
Published: December 2007

A macroflora from John Peaks, Powell Island, contains Sagenopteris nilssoniana, Cladophlebis oblonga, Brachyphyllum sp., Elatocladus confertus, and Sphenopteris sp. The macroflora is best correlated with the Botany Bay Group flora, suggesting an Early to Middle Jurassic age for the Powell Island Conglomerate. This age supports new interpretations for the geological evolution of the Antarctic Peninsula that suggest the initial phase of Gondwana break-up was manifested as small rift grabens with continental deposits.
Late Triassic plant microfossils from Miers Bluff Formation of Livingston Island, South Shetland Islands, Antarctica
Authors: Shu Ouyang , Xi-Guang Deng , Yan-Bin Shen , Xiang-Shen Zheng , Xiao-Han Liu
Published: December 2007

A moderately diverse assemblage of plant microfossils has been recovered from the Johnsons Dock Member of the Miers Bluff Formation, Livingston Island, including spores, pollen, acritarchs, wood fragments and cuticles. Containing a total of c. 45 of miospore taxa, the palynoflora is dominated by non-striate bisaccate pollen, but spores of pteridophytes and pollen of gymnosperms are proportionate in diversity. The palynoflora is similar in composition to those indicative of subzones C + D of the Alisporites Zone of Antarctica, and the upper Craterisporites rotundus Zone and the lower Polycingulatisporites crenulatus Zone of Australia as well as the upper Polycingulatisporites crenulatus Zone and Foveosporites moretonensis Zone of New Zealand, suggesting a Late Triassic (possibly Norian–Rhaetian) age. This determination is supported by the sporadic occurrence of Aratrisporites and Classopollis in the palynoflora as well as by the absence of striate bisaccate grains.
Mesoscale meteorological conditions in Dronning Maud Land, Antarctica, during summer: the momentum budget of the boundary layer
Authors: Bintanja Richard
Published: December 2007

The momentum budget of the boundary layer flew near the Swedish research station Svea in the mountainous region of western Dronning Maud Land, Antarctica, is evaluated using detailed concurrent observations of surface meteorological variables, high-resolution boundary layer profiles and upper-air profiles taken during the summer of 1997–98. Despite the fact that the irregular topographical situation prohibits easy interpretation of the data, interesting features can still be identified. All terms in the momentum budget (katabatic forcing, synoptic pressure gradient, Coriolis force and friction) can be of the same order of magnitude, which indicates that the influence of each term depends largely on the prevailing conditions. More precisely, the relative importance of the various momentum terms varies strongly with altitude, location, time of day and prevailing synoptic conditions. For example, at the undisturbed snow slopes there is a very regular daily variation of katabatically forced flow during the night and a flow dominated by the synoptic pressure gradient during the day, causing a persistent diurnal cycle in surface wind direction. The interpretation of the flow characteristics in terms of the momentum budget agrees favourably with the conclusions drawn on the basis of a general description of the prevailing meteorological conditions, and can therefore be considered consistent.
Evolution in the cold
Authors: Clarke Andrew
Published: December 2007

Theodosius Dobzhansky once remarked that nothing in biology makes sense other than in the light of evolution, thereby emphasising the central role of evolutionary studies in providing the theoretical context for all of biology. It is perhaps surprising then that evolutionary biology has played such a small role to date in Antarctic science. This is particularly so when it is recognised that the polar regions provide us with an unrivalled laboratory within which to undertake evolutionary studies. The Antarctic exhibits one of the classic examples of a resistance adaptation (antifreeze peptides and glycopeptides, first described from Antarctic fish), and provides textbook examples of adaptive radiations (for example amphipod crustaceans and notothenioid fish). The land is still largely in the grip of major glaciation, and the once rich terrestrial floras and faunas of Cenozoic Gondwana are now highly depauperate and confined to relatively small patches of habitat, often extremely isolated from other such patches. Unlike the Arctic, where organisms are returning to newly deglaciated land from refugia on the continental landmasses to the south, recolonization of Antarctica has had to take place by the dispersal of propagules over vast distances. Antarctica thus offers an insight into the evolutionary responses of terrestrial floras and faunas to extreme climatic change unrivalled in the world. The sea forms a strong contrast to the land in that here the impact of climate appears to have been less severe, at least in as much as few elements of the fauna show convincing signs of having been completely eradicated.
Molecular zoogeography of Antarctic euphausiids and notothenioids: from species phylogenies to intraspecific patterns of genetic variation
Authors: Bargelloni Luca , Zane Lorenzo , Derome Nicolas , Lecointre Guillaume , Patarnello Tomaso
Published: December 2007

Published and unpublished data are used to investigate possible mechanisms of species diversification in two key groups of Antarctic organisms: the Notothenioidei and the Euphausiidae. Species distributions are mapped onto molecular phylogenies, and this evidence is interpreted in light of the various ecological and historical factors which characterize the Southern Ocean. The joint effect of diverse agents (vicariance, “jump” dispersal) appears to be determinant in several cases for species divergence. A review of results from population genetics studies, together with new molecular evidence, confirm the importance of physical barriers (oceanographic fronts) in reducing migration, thereby promoting speciation, at least in notothenioids.
Hypotheses on Southern Ocean peracarid evolution and radiation (Crustacea, Malacostraca)
Authors: Brandt A.
Published: December 2007

A short summary of some the most important hypotheses on the evolution of Southern Ocean peracarid crustaceans and some of the potential reasons for the high biodiversity of this taxon is presented. Besides the knowledge of horizontal and vertical distribution patterns of Southern Ocean peracarids, the importance of the evolution of the notothenioid fishes on the evolution of the Peracarida is discussed. Key questions for a better understanding of evolutionary biology of Southern Ocean Peracarida are highlighted.
Molecular tools for understanding population structure in Antarctic species
Authors: Gaffney Patrick M.
Published: December 2007

During the last decade, methods for detecting DNA polymorphisms have proliferated at a bewildering pace. Today the investigator must choose among various types of genetic markers as well as between a variety of methods for discovering and screening polymorphisms. Polymorphisms useful for the analysis of population structure are found in both mitochondrial and nuclear genomes. Marker development may proceed along two routes: 1) discovery of species–specific markers, and 2) application of universal methods. Species-specific markers are based on sequence data from the target species or close relatives, whereas universal markers are based on the use of polymerase chain reaction (PCR) primers targeted to regions highly conserved across diverse taxa. Markers commonly employed include mitochondrial DNA polymorphisms, microsatellites, anonymous nuclear loci and known genes (both coding and noncoding regions). Methods for detecting polymorphisms range from technically simple (RFLP analysis) to more sophisticated mutation scanning methods. We review the application of these approaches to several key Antarctic species (the Patagonian toothfish Dissostichus eleginoides, the mackerel icefish Champsocephalus gunnari, and the squid Martialia hyadesi Rochebrune & Mabille, 1889) and present preliminary data on genetic polymorphisms in toothfish and icefish.
Genetic diversity in the marine phytoplankton: a review and a consideration of Antarctic phytoplankton
Authors: Medlin Linda K. , Lange Martin , Nöthig Eva-Maria
Published: December 2007

Molecular analysis of phytoplankton population structure has lagged behind other groups and has usually been inferred from physiological data determined from relatively few clones. Nearly every physiological measurement has shown that no single clone of any phytoplankton species can be considered truly representative of that species. One important reason why studies of phytoplankton population structure are perhaps 20 or more years behind those of other organisms is because of the necessity to establish clonal cultures prior to genetic analysis and the inability to perform fine-scale sampling under most conditions. Isozyme analysis, performed for a few species, has revealed heterozygosity between populations. In addition, fingerprinting analyses, such as Random Amplified Polymorphic DNAs (RAPDs) or multi-locus probes, have shown that phytoplankton blooms are not mono-clonal, are highly diverse and isolates are related by geographic origin. In the Southern Ocean, only two studies have been made of the population structure of phytoplankton. The first, based on quantitative genetic analysis of morphometric features, suggests that there is sufficient genetic variation in populations of Thalassiosira tumida to allow speciation in terms of major shifts in morphology under conditions of continued directional selection. The second, using sequence data from the noncoding regions of the internal transcribed spacer region (ITS) in the ribosomal cistron as a molecular marker, shows that populations of Phaeocystis antarctica within continental water masses are homogenous with little evidence of population structure. Populations found within the Antarctic Circumpolar Current are genetically distinct from others, suggesting the currents also play an important role in determining population structure in phytoplankton populations.
Chromosome change and the evolution in the Antarctic fish suborder Notothenioidei
Authors: Pisano Eva , Ozouf-Costaz Catherine
Published: December 2007

The majority of species of the Antarctic coastal fish fauna is represented today by the perciform suborder Notothenioidei. The separation of basal lineages of notothenioids has been estimated to have occurred between 23 and 22 million years ago (m.y.a.), while a major diversification probably occurred 16–10 m.y.a. Cytogenetic approaches aim to study the genomic change that, at the cell level, accompanied the radiation of this group. The information available for 66 of 120–130 species makes possible the description of the main patterns of chromosome diversification within the suborder. Within some families (Channichthyidae, Artedidraconidae) the range of the chromosomal variability seems to be minimal whilst the high karyotypic diversity of Nototheniidae and Bathydraconidae is consistent with morphological and molecular data suggesting the paraphyletic nature of these two taxa. Molecular cytogenetics allows detailed chromosome characterization, including mapping of ribosomal genes and of telomeric sequences, thus providing information on processes of karyotypic rearrangement and direction of chromosomal change. Active process of genomic restructuring leads to intraspecific variability in several species, at different levels of chromosomal organization. The growing amount of information make it possible to use notothenioids as a model for testing hypotheses of evolutionary change in marine organisms, including chromosomal diversification.
The terrestrial biota of Charcot Island, eastern Bellingshausen Sea, Antarctica: an example of extreme isolation
Authors: Convey P. , Smith R.I.L. , Peat H.J. , Pugh P.J.A.
Published: December 2007

This paper documents the previously undescribed terrestrial fauna (mites, nematodes, tardigrades) and flora (liverworts, mosses and lichens) of Marion Nunataks, Charcot Island (69°45'S 075°15'W). Species diversity in all groups is low relative to other Maritime Antarctic sites, probably a twin function of very limited ice-free terrain and extreme isolation. The fauna and flora are wholly immigrant and, with the exceptions of two lichens (Psilolechia lucida and Umbilicaria aff. thamnodes), clearly derived from the Maritime Antarctic. The fauna is unique for the Maritime Antarctic in that it appears to contain neither predatory arthropods nor Collembola (springtails), which are otherwise ubiquitous and important members of the terrestrial fauna of the zone. The flora includes exceptional development of three mosses that are encountered only rarely at latitudes south of c. 65°S, Brachythecium austrosalebrosum, Dicranoweisia crispula and Polytrichum piliferum. The southern limit for several mosses and lichens has been extended. This small and isolated site is extremely vulnerable to accidental human-mediated introduction of both native Antarctic and alien biota.