bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecular Mechanisms of Ultraviolet Radiation‐Induced DNA Damage and Repair
Authors: Rastogi Rajesh P. , Richa  , Kumar Ashok , Tyagi Madhu B. , Sinha Rajeshwar P.
Published: December 2010

DNA is one of the prime molecules, and its stability is of utmost importance for proper functioning and existence of all living systems. Genotoxic chemicals and radiations exert adverse effects on genome stability. Ultraviolet radiation (UVR) (mainly UV‐B: 280–315 nm) is one of the powerful agents that can alter the normal state of life by inducing a variety of mutagenic and cytotoxic DNA lesions such as cyclobutane‐pyrimidine dimers (CPDs), 6‐4 photoproducts (6‐4PPs), and their Dewar valence isomers as well as DNA strand breaks by interfering the genome integrity. To counteract these lesions, organisms have developed a number of highly conserved repair mechanisms such as photoreactivation, base excision repair (BER), nucleotide excision repair (NER), and mismatch repair (MMR). Additionally, double‐strand break repair (by homologous recombination and nonhomologous end joining), SOS response, cell‐cycle checkpoints, and programmed cell death (apoptosis) are also operative in various organisms with the expense of specific gene products. This review deals with UV‐induced alterations in DNA and its maintenance by various repair mechanisms.
Pramipexole Extended Release: A Novel Treatment Option in Parkinson's Disease
Authors: Eisenreich Wolfram , Sommer Bernd , Hartter Sebastian , Jost Wolfgang H.
Published: December 2010

Pramipexole, the most commonly prescribed dopamine agonist worldwide, meanwhile serves as a reference substance for evaluation of new drugs. Based on numerous clinical data and vast experiences, efficacy and safety profiles of this non-ergoline dopamine agonist are well characterized. Since October 2009, an extended-release formulation of pramipexole has been available for symptomatic treatment of Parkinson's disease. Pramipexole administration can be cut down from three times to once a day due to the newly developed extended-release formulation. This is considerable progress in regard to minimizing pill burden and enhancing compliance. Moreover, the 24 h continuous drug release of the once-daily extended-release formulation results in fewer fluctuations in plasma concentrations over time compared to immediate-release pramipexole, given three times daily. The present study summarizes pharmacokinetics and all essential pharmacological and clinical characteristics of the extended-release formulation. In addition, it provides all study data, available so far, with regard to transition and de-novo administration of extended-release formulation for patients with Parkinson's disease. It further compares efficacy and safety data of immediate-release pramipexole with the extended-release formulation of pramipexole.
Controversies of Treatment Modalities for Cerebral Venous Thrombosis
Authors: Khan Maria , Kamal Ayeesha Kamran , Wasay Mohammad
Published: December 2010

Cerebral vein thrombosis has been well recognized for nearly two centuries. However, therapeutic options for the condition are limited due to lack of large randomized trials. The various modalities reportedly used include antiplatelets, anticoagulation, fibrinolysis, and mechanical thrombectomy. Of these, antiplatelets are the least studied, and there are only anecdotal reports of aspirin use. Anticoagulation is the most widely used and accepted modality with favorable outcomes documented in two randomized controlled trials. Various fibrinolytic agents have also been tried. Local infusions have shown more promise compared to systemic agents. Similarly, mechanical thrombectomy has been used to augment the effects of chemical thrombolysis. However, in the absence of randomized controlled trials; there is no concrete evidence of the safety and efficacy of either of these modalities. Limited study series disclosed that decompression surgery in malignant CVT can be life saving and provides good neurological outcome in some cases.Conclusion. Overall therapeutics for CVT need larger randomized controlled trials. Anticoagulaion with heparin is the only modality with a reasonable evidence to support its use in CVT. Endovascular thrombolysis and mechanical thrombectomy are reserved for selected cases who fail anticoagulation and decompression surgery for malignant CVT with impending herniation.
Prognostic Factors in Advanced Non-Small-Cell Lung Cancer Patients: Patient Characteristics and Type of Chemotherapy
Authors: Abbasi Salah , Badheeb Ahmed
Published: December 2010

Eleven prognostic factors were retrospectively analyzed in 270 newly diagnosed patients with advanced non-small-cell lung cancer including age, sex, performance status, histology, stage, smoking status, hemoglobin level, forced expiratory volume in one second (FEV1), weight loss >5% in 3 months preceding therapy, number of involved organs, and type of first-line chemotherapy.
Response rate was 35.6%, and median survival was 8.2 months (95% CI, 7.8 to 8.7) for the whole group. Age ≤60 years (), (), and the use of platinum/docetaxel () were significantly associated with an improved survival. Histology did not affect outcome in the absence of targeted therapies.
Systematic Review of the Effect of Diet and Exercise Lifestyle Interventions in the Secondary Prevention of Coronary Heart Disease
Authors: Cole Judith A. , Smith Susan M. , Hart Nigel , Cupples Margaret E.
Published: December 2010

The effectiveness of lifestyle interventions within secondary prevention of coronary heart disease (CHD) remains unclear. This systematic review aimed to determine their effectiveness and included randomized controlled trials of lifestyle interventions, in primary care or community settings, with a minimum follow-up of three months, published since 1990. 21 trials with 10,799 patients were included; the interventions were multifactorial (10), educational (4), psychological (3), dietary (1), organisational (2), and exercise (1). The overall results for modifiable risk factors suggested improvements in dietary and exercise outcomes but no overall effect on smoking outcomes. In trials that examined mortality and morbidity, significant benefits were reported for total mortality (in 4 of 6 trials; overall risk ratio (RR) 0.75 (95% confidence intervals (CI) 0.65, 0.87)), cardiovascular mortality (3 of 8 trials; overall RR 0.63 (95% CI 0.47, 0.84)), and nonfatal cardiac events (5 of 9 trials; overall RR 0.68 (95% CI 0.55, 0.84)). The heterogeneity between trials and generally poor quality of trials make any concrete conclusions difficult. However, the beneficial effects observed in this review are encouraging and should stimulate further research.
E22Δ Mutation in Amyloid β‐Protein Promotes β‐Sheet Transformation, Radical Production, and Synaptotoxicity, But Not Neurotoxicity
Authors: Suzuki Takayuki , Murakami Kazuma , Izuo Naotaka , Kume Toshiaki , Akaike Akinori , Nagata Tetsu , Nishizaki Tomoyuki , Tomiyama Takami , Takuma Hiroshi , Mori Hiroshi , Irie Kazuhiro
Published: December 2010

Oligomers of 40‐ or 42‐mer amyloid β‐protein (Aβ40, Aβ42) cause cognitive decline and synaptic dysfunction in Alzheimer′s disease. We proposed the importance of a turn at Glu22 and Asp23 of Aβ42 to induce its neurotoxicity through the formation of radicals. Recently, a novel deletion mutant at Glu22 (E22Δ) of Aβ42 was reported to accelerate oligomerization and synaptotoxicity. To investigate this mechanism, the effects of the E22Δ mutation in Aβ42 and Aβ40 on the transformation of β‐sheets, radical production, and neurotoxicity were examined. Both mutants promoted β‐sheet transformation and the formation of radicals, while their neurotoxicity was negative. In contrast, E22P‐Aβ42 with a turn at Glu22 and Asp23 exhibited potent neurotoxicity along with the ability to form radicals and potent synaptotoxicity. These data suggest that conformational change in E22Δ‐Aβ is similar to that in E22P‐Aβ42 but not the same, since E22Δ‐Aβ42 exhibited no cytotoxicity, unlike E22P‐Aβ42 and wild‐type Aβ42.
Placing the RPL32 Promoter Upstream of a Second Promoter Results in a Strongly Increased Number of Stably Transfected Mammalian Cell Lines That Display High Protein Expression Levels
Authors: Hoeksema F. , Hamer K. , Siep M. , Verhees J. A. , Otte A. P.
Published: December 2010

The use of high stringency selection systems commonly results in a strongly diminished number of stably transfected mammalian cell lines. Here we placed twelve different promoters upstream of an adjacent primary promoter and tested whether this might result in an increased number of colonies; this is in the context of a stringent selection system. We found that only the promoter of the human ribosomal protein, RPL32, induced a high number of colonies in CHO-DG44 cells. This phenomenon was observed when the RPL32 promoter was combined with the CMV, SV40, EF1-α, and theβ-actin promoters. In addition, these colonies displayed high protein expression levels. The RPL32 promoter had to be functionally intact, since the deletion of a small region upstream of the transcription start site demolished its positive action. We conclude that adding the RPL32 promoter to an expression cassettein cismay be a powerful tool to augment gene expression levels.
Incidence of Stroke in Young Adults: A Review
Authors: Marini Carmine , Russo Tommasina , Felzani Giorgio
Published: December 2010

Introduction. Stroke in the young may have a dramatic impact on the quality of life in survivors. This study was aimed to evaluate incidence of first-ever stroke in the young by means of a systematic review.Materials and Methods. All papers on incidence of stroke in the young published after 1980, were identified by electronic search of Medline and manual search of reference lists. Only studies recruiting subjects under 44 years of age and with a lower age limit not higher than 20 years were included. Incidence rates were standardized to the 2000 European population according to the direct method. Poisson regression analysis was used to compare studies.Results. 29 studies including 3548 participants were identified. Incidence rates, after excluding a few outliers, ranged between 8.63 and 19.12 for crude rates and between 8.70 and 21.02 for standardized rates. Heterogeneity among studies was statistically significant but improved after excluding 4 studies. Few studies reported the proportions of stroke subtypes.Conclusions.Stroke in subjects under 45 years of age is not such a rare disease and requires specific preventive programs.
Irreversible Anterior Ischemic Optic Neuropathy Complicating Interferon Alpha and Ribaverin Therapy
Authors: Seddik Hassan , Tamzaourte Mouna , Rouibaa Fadoua , Fadlouallah Maha , Benkirane Ahmed
Published: December 2010

Ophthalmologic complications with interferon therapy are rare and usually reversible. The anterior ischemic optic neuropathy is an uncommon complication of interferon treatment. A case of irreversible anterior ischemic optic neuropathy complicating interferon therapy for chronic hepatitis C is reported. We suggest that periodic ophthalmological examinations, including visual acuity and fundus examinations, should be performed to patients with high risk of ocular complications after starting and during treatment. We also suggest that an ophthalmologist would be able to detect these complications. Antiviral treatment should be stopped immediately if severe ophthalmologic complications occur.
Androidal Fat Dominates in Predicting Cardiometabolic Risk in Postmenopausal Women
Authors: Matvienko O. A. , Alekel D. L. , Bhupathiraju S. N. , Hofmann H. , Ritland L. M. , Reddy M. B. , Van Loan M. D. , Perry C. D.
Published: December 2010

We hypothesized that soy isoflavones would attenuate the anticipated increase in androidal fat mass in postmenopausal women during the 36-month treatment, and thereby favorably modify the circulating cardiometabolic risk factors: triacylglycerol, LDL-C, HDL-C, glucose, insulin, uric acid, C-reactive protein, fibrinogen, and homocysteine. We collected data on 224 healthy postmenopausal women at risk for osteoporosis (45.8–65 y, median BMI 24.5) who consumed placebo or soy isoflavones (80 or 120 mg/d) for 36 months and used longitudinal analysis to examine the contribution of isoflavone treatment, androidal fat mass, other biologic factors, and dietary quality to cardiometabolic outcomes. Except for homocysteine, each cardiometabolic outcome model was significant (overall -values from ≤.0001 to .0028). Androidal fat mass was typically the strongest covariate in each model. Isoflavone treatment did not influence any of the outcomes. Thus, androidal fat mass, but not isoflavonetreatment, is likely to alter the cardiometabolic profile in healthy postmenopausal women.
Renal Cell Carcinoma: Focus on Safety and Efficacy of Temsirolimus
Authors: Hadoux Julien , Vignot Stephane , De La Motte Rouge Thibault
Published: December 2010

Metastatic renal cell carcinoma has harboured a poor prognosis for decades with immunotherapy being the only available therapy with high toxicity and modest effect. Dependance of renal cell carcinoma oncogenesis on the mTOR pathway has led to clinical development of temsirolimus in this setting. This sirolimus derivative has shown clinical efficacy in monotherapy for poor-risk renal cell carcinoma leading to an overall survival of 10.8 months in the pivotal phase III trial of this agent. Its specific adverse events consist of metabolic dysregulation (hyperlipemia, hyperglycemia), mucositis, rash and pneumonitis which can be severe and need careful monitoring and management. In this review, we will discuss of the clinical development of this molecule, its efficacy, its safety profile and future perspectives.
Efficacy and Tolerability after Unusually Low Doses of Dasatinib in Chronic Myeloid Leukemia Patients Intolerant to Standard-Dose Dasatinib Therapy
Authors: Serpa Mariana , Sanabani Sabri S. , Bendit Israel , Seguro Fernanda , Xavier Flávia , Barroso Cláudia Bitti , Conchon Monika , Dorlhiac-Llacer Pedro Enrique
Published: December 2010

We report our experience in 4 patients with chronic myeloid leukemia (CML) who had discontinued imatinib as a result of adverse events and had switched to dasatinib. The chronic phase ( n 2) and accelerated phase ( n 2) CML patients received dasatinib at starting dose of 100 and 140 mg once daily, respectively. Reappearance of hematological toxicity was observed in 3 patients and pancreatitis in one patient. Treatment was given at a lower dose and patients were followed. The median follow-up was 13 months and the median dose of dasatinib until achievement of complete cytogenetic remission (CCyR) was 60 mg daily (range = 20 to 120 mg). All four patients had achieved CCyR at a median of 4 months (range = 3 to 5 months) and among them, three had also achieved major molecular remission. We conclude that low-dose dasatinib therapy in intolerant patients appears safe and efficacious and may be tried before drug discontinuation.
A Case of Transient ACTH Deficiency Associated with Polymyalgia Rheumatica
Authors: Nishi Hitoo , Nishi Yuichi , Yagita Masato , Tamaru Yoshiko , Matsumoto Sadayuki , Koshiyama Hiroyuki
Published: December 2010

We report a case of 79-year-old man, who was diagnosed to have transient ACTH deficiency associated with polymyalgia rheumatica (PMR). The patient presented with sudden onset bilateral shoulder pain, which was gradually aggravated. Plasma ACTH was undetectable, and both serum cortisol and urinary 17-OHCS were very low. Other pituitary hormones were normal, suggesting that hypothalamo-pituitary-adrenal (HPA) axis is selectively damaged. However, within several weeks, plasma ACTH returned to normal, and showed a normal increase response to corticotropin-releasing hormone stimulation test. These results indicated that ACTH deficiency was only transient. After hydrocortisone (10 mg/day) was administered, his symptoms became suddenly improved. Based on those results and clinical course, ie, elevated erythrocyte sedimentation rate, negative rheumatoid factor and the typical symptoms, which showed improvement to glulcocorticoid therapy, the final diagnosis was PMR, which was associated with transient ACTH deficiency. This is the first report of a case of PMR, in which the HPA axis was examined in its very acute phase. It was demonstrated that the case was associated with the transient adrenocortical hypofunction, which was recovered during a short time. It is therefore possible that PMR may show a different responsiveness of HPA axis depending on its phases.
Bevasiranib for the Treatment of Wet, Age-Related Macular Degeneration
Authors: Garba Adinoyi O. , Mousa Shaker A.
Published: December 2010

Age- related Macular Degeneration (AMD) is the leading cause of severe visual impairment in people 65 years and older in industrialized nations. Exudative, or “wet”, AMD is a late form of AMD (as distinguished from atrophic, so-called dry, AMD) and is responsible for over 60% of all cases of blindness due to AMD. It is widely accepted that vascular endothelial growth factor (VEGF) is a key component in the pathogenesis of choroidal neo-vascularization (CNV), which is a precursor to wet AMD. The current gold-standard for treating wet AMD is the monoclonal antibody fragment ranibizumab (trade name Lucentis), which targets VEGF. Other agents used to treat wet AMD include pegaptanib (Macugen), bevacizumab (Avastin; off-label use), and several other experimental agents. The advent of small interfering RNA (siRNA) has presented a whole new approach to inhibiting VEGF. This article reviews the status of a novel siRNA-based therapeutic, bevasiranib, for the treatment of wet AMD. Bevasiranib is believed to work by down regulating VEGF production in the retina. Studies in human cell-lines and animal models have shown that VEGF siRNAs are effective in inhibiting VEGF production. Although there is a lack of sufficient published data on human studies supporting the use of bevasiranib for wet AMD, available data indicates that due to its unique mechanism of action, bevasiranib might hold some promise as a primary or adjunct treatment for wet AMD.
C*-algebras associated with integral domains and crossed products by actions on adele spaces
Authors: Cuntz Joachim , Li Xin
Published: December 2010

We compute the K-theory for C*-algebras naturally associated with rings of integers in number fields.

The main ingredient is a duality theorem for arbitrary global fields. It allows us to identify the crossed product arising from affine transformations on the finite adeles with the analogous crossed product algebra over the infinite adele space.
Noncommutative Yang–Mills–Higgs actions from derivation-based differential calculus
Authors: Cagnache Eric , Masson Thierry , Wallet Jean-Christophe
Published: December 2010

Derivations of a noncommutative algebra can be used to construct differential calculi, the so-called derivation-based differential calculi. We apply this framework to a version of the Moyal algebra

\mathcal M

. We show that the differential calculus, generated by the maximal subalgebra of the derivation algebra of

\mathcal M

that can be related to infinitesimal symplectomorphisms, gives rise to a natural construction of Yang–Mills–Higgs models on

\mathcal M

and a natural interpretation of the covariant coordinates as Higgs fields. We also compare in detail the main mathematical properties characterizing the present situation to those specific of two other noncommutative geometries, namely the finite dimensional matrix algebra

M_n(ℂ)

and the algebra of matrix valued functions

C^∞(M) \otimes M_n(ℂ)

. The UV/IR mixing problem of the resulting Yang–Mills–Higgs models is also discussed.
Van den Bergh isomorphisms in string topology
Authors: Menichi Luc
Published: December 2010

Let

M

be a path-connected closed oriented

d

-dimensional smooth manifold and let

\mathbb{k}

be a principal ideal domain. By Chas and Sullivan, the shifted free loop space homology of

M

,

H_{*+d}(\mathrm{L}\mkern-1.5mu M )

is a Batalin–Vilkovisky algebra. Let

G

be a topological group such that

M

is a classifying space of

G

. Denote by

S_*(G)

the (normalized) singular chains on

G

. Suppose that

G

is discrete or path-connected. We show that there is a Van Den Bergh type isomorphism

\mathrm{HH}^{-p}(S_*(G),S_*(G))\cong \mathrm{HH}_{p+d}(S_*(G),S_*(G)).

Therefore, the Gerstenhaber algebra

\mathrm{HH}^{*}(S_*(G),S_*(G))

is a Batalin–Vilkovisky algebra and we have a linear isomorphism

\mathrm{HH}^{*}(S_*(G),S_*(G))\cong H_{*+d}(\mathrm{L}\mkern-1.5mu M ).

This linear isomorphism is expected to be an isomorphism of Batalin–Vilkovisky algebras. We also give a new characterization of Batalin–Vilkovisky algebra in terms of the derived bracket.
The index of hypoelliptic operators on foliated manifolds
Authors: van Erp Erik
Published: December 2010

In [vE1] and [vE2] we presented the solution to the index problem for a class of hypoelliptic operators on closed contact manifolds. The proofs are based on an adaptation of the tangent groupoid method of Alain Connes to hypoelliptic index problems. The methods originally developed for contact manifolds have wider applicability to the index theory of hypoelliptic Fredholm operators. As an illustration of the scope and effectiveness of these methods, we present here an index theorem for a class of hypoelliptic differential operators on closed foliated manifolds.
Roughness Effects on Continuous and Discrete Flows in Superhydrophobic Microchannels
Authors: Zhang Junfeng , Kwok Daniel Y.
Published: December 2010

The dynamic behaviors of continuous and discrete flows in superhydrophobic microchannels are investigated with a lattice Boltzmann model. Typical characters of the superhydrophobic phenomenon are well observed from our simulations, including air trapped in the surface microstructures, high contact angles, low contact angle hysteresis, and reduced friction to fluid motions. Increasing the roughness of a hydrophobic surface can produce a large flow rate through the channel due to the trapped air, implying less friction or large apparent slip. The apparent slip length appears to be independent to the channel width and could be considered as a surface property. For a moving droplet, its behavior is affected by the surface roughness from two aspects: the contact angle difference between its two ends and the surface-liquid interfacial friction. As a consequence, the resulting droplet velocity changes with the surface roughness as firstly decreasing and then increasing. Simulation results are also compared with experimental observations and better agreement has been obtained than that from other numerical method. The information from this study could be valuable for microfluidic systems.
Phytoplankton community composition can be predicted best in terms of morphological groups
Authors: Kruk C. , Peeters E.T.H.M. , Van Nes E. H. , Huszar V. L. M. , Costa L. S. , Scheffer M.
Published: December 2010

We explored how well the aggregated biovolume of groups of species can be predicted from environmental variables using three different classification approaches: morphology‐based functional groups, phylogenetic groups, and functional groups proposed by Reynolds. We assessed the relationships between biovolume of each group and environmental conditions using canonical correlation analyses as well as multiple linear regressions, using data from 211 lakes worldwide ranging from subpolar to tropical regions. We compared the results of these analyses with those obtained for single species following the same protocol. While some species appear relatively predictable, a vast majority of the species showed no clear relationship to the environmental conditions we had measured. However, both the multivariate and the regression analyses indicated that morphology‐based groups can be predicted better from environmental conditions than groups based on the other classification methods. This suggests that morphology captures ecological function of phytoplankton well, and that functional groups based on morphology may be the most suitable focus for predicting the composition of communities.
Partitioning of primary production among giant kelp (Macrocystis pyrifera), understory macroalgae, and phytoplankton on a temperate reef
Authors: Miller Robert J. , Reed Daniel C. , Brzezinski Mark A.
Published: December 2010

We experimentally investigated the response of phytoplankton and understory macroalgae to canopies of giant kelp, Macrocystis pyrifera, by following changes in their biomass and net primary production over 17 months in 600‐m2 plots where giant kelp was continually removed or left intact and allowed to vary naturally. Production by phytoplankton was two times greater and understory algae five times greater where Macrocystis was removed relative to the intact forest. Understory biomass, but not phytoplankton biomass, was suppressed inside the forest, leading to a higher magnitude of effect on net primary production (NPP) by understory relative to phytoplankton. Following a natural decline of the Macrocystis canopy by winter storms, understory macroalgae and phytoplankton increased production in the Macrocystis control plot. This response was delayed for both groups, with phytoplankton production increasing in spring and understory increasing later during summer. The longer delay for understory macroalgae was likely due to restrictions in the timing of macroalgal recruitment and their slower growth rates compared with phytoplankton and with increased competition for light resulting from greater light absorption by the spring phytoplankton bloom. Surprisingly, total ecosystem production that included NPP by Macrocystis, phytoplankton, and understory algae did not differ between the Macrocystis control and removal plots for much of the study. NPP by understory algae, which comprised the bulk of the ecosystem NPP in the Macrocystis removal plot, can compensate to varying degrees for the loss of Macrocystis production following its removal by winter storms.
Structural and phylogenetic analysis of a novel ζ‐carotene desaturase from Dunaliella bardawil, a unicellular alga that accumulates large amounts of β‐carotene
Authors: Ye Zhi-Wei , Liu Guan-Nan , Jiang Jian-Guo
Published: December 2010

Due to the high demand for carotenoids in the global market, more and more attention is being paid to the molecular elucidation of carotenogenesis in Dunaliella for the massive production of β‐carotene. The complementary deoxyribonucleic acid (cDNA) of a novel carotenogenic enzyme, ζ‐carotene desaturase (Zds), was isolated from Dunaliella bardawil using polymerase chain reaction. The full‐length cDNA was 2209 base pairs (bp) long, containing an 1749‐bp putative open reading frame that encoded a deduced protein sequence of 582 amino acids with an estimated molecular weight of 64.429 kDa. The D. bardawil Zds was a nonsecretory protein that may be located in the chloroplast. The D. bardawil Zds had a closer relationship with chlorophyte and higher plants Zdses than with those of other species in the phylogenetic analysis. The three‐dimensional structure of the D. bardawil Zds is predicted.
Increased rate of D1 repair in coral symbionts during bleaching is insufficient to counter accelerated photo‐inactivation
Authors: Hill Ross , Brown Christopher M. , DeZeeuw Katrina , Campbell Douglas A. , Ralph Peter J.
Published: December 2010

We dissect the primary photo‐inactivation and the counteracting metabolic repair rates in fragments of the scleractinian coral, Pocillopora damicornis, subjected to a combined stress of a shift to elevated temperature (from 26°C to 32°C) and increased light (from 200 µmol photons m−2 s−1 to 400 µmol photons m−2 s−1) to induce bleaching. During the bleaching treatment the dinoflagellate symbionts showed a 5.5‐fold acceleration in their photosystem II (PSII) repair rate constant, demonstrating that they maintain strong metabolic capacity to clear and replace photo‐damaged D1 protein at the elevated temperature and light conditions. Nevertheless, the symbionts concurrently suffered a seven‐fold increase in the rate constant for PSII photo‐inactivation. This rapid photo‐inactivation exceeded the PSII repair capacity, therefore tipping the symbionts, and by implication the symbiosis, into net photo‐inhibition. Increased photo‐inactivation in hospite, rather than an inhibition of PSII repair, is the principle trigger for net photo‐inhibition under bleaching conditions.
Silicon uptake and supply during a Southern Ocean iron fertilization experiment (EIFEX) tracked by Si isotopes
Authors: Cavagna A.-J. , Fripiat F. , Dehairs F. , Wolf-Gladrow D. , Cisewski B. , Savoye N. , Andrè L. , Cardinal D.
Published: December 2010

We studied the evolution of the isotopic composition of dissolved Si (δ30SiDSi) and biogenic Si (δ30SiBSi) during a diatom bloom induced by an iron fertilization experiment in a Southern Ocean (SO) eddy. Dissolved Si (DSi) consumption was clearly boosted as a result of iron addition. We estimate an apparent Si isotopic fractionation factor of 21.36% ± 0.11%, not significantly different from estimates based on in vitro incubations under Fe‐replete conditions and in agreement with previous SO studies under Fe‐depleted conditions. The temporal variations of the δ30SiSi are best reconstructed considering the fertilized surface waters as an open system, i.e., DSi is continuously supplied from the winter water. Using vertical diffusivity, we estimate a supply of 6.7 ± 1.2 mmol Si m−2 d−1 representing 30% ± 5% of total DSi demand. We estimate biogenic silica (BSi) production at 22.1 ± 1.8 mmol Si m−2 d−1, similar to BSi production under natural conditions in the SO. The DSi use preceding the start of the fertilization was conservatively estimated at 49% ± 4%, and as a result of the Fe‐fertilization, a further 31% ± 4% of the initial DSi reservoir was consumed. The BSi export was estimated to be 17.4 ± 1.7 mmol Si m−2 d−1. Our results suggest that for this study three main processes were acting significantly on δ30SiSi signatures, biological uptake, Si supply from subsurface, and export of BSi, and that the magnitude of production and export in such a Fe‐fertilized experiment are similar to those for natural diatom blooms occurring in the Southern Ocean.
Larval retention, entrainment, and accumulation in the lee of a small headland: Recruitment hotspots along windy coasts
Authors: Morgan Steven G. , Fisher Jennifer L. , Largier John L.
Published: December 2010

We surveyed crustacean larvae in the plankton in the lee of Bodega Head, California, for 2 months during late spring and summer and cross‐correlated the larval abundance and stage of development of 16 taxa with 8 indicators of upwelling‐relaxation conditions. Larvae in all stages of development for 11 of these taxa were entrained and accumulated in a recirculation feature in Bodega Bay, found in the lee of this small headland as soon as upwelling‐favorable winds began, and persisted until winds weakened. The remaining taxa were more prevalent during relaxation events when the recirculation feature dissipated and a poleward coastal current transported larvae into and through the bay. During upwelling conditions, a vertically sheared flow occurs in the lee of the headland that accounts for the accumulation of plankton. However, larval behavior did not have a substantial effect on density and persistence in the lee of the headland, regardless of whether taxa were more prevalent during upwelling or relaxation conditions or whether they developed entirely nearshore or migrated offshore later in development. Thus, larvae and postlarvae of many, diverse taxa are concentrated in the plankton in the lee of small headlands in upwelling areas, which is consistent with previously reported recruitment hot spots in small upwelling bays. These headland‐related hot spots increase spatial structure in population density and community structure in recruitment‐limited upwelling regions and other wind‐driven coasts.
Direct and indirect effects of an invasive planktonic predator on pelagic food webs
Authors: Strecker Angela L. , Beisner Beatrix E. , Arnott Shelley E. , Paterson Andrew M. , Winter Jennifer G. , Johannsson Ora E. , Yan Norman D.
Published: December 2010

The relative importance of top‐down invader effects relative to environmental drivers was determined by sampling crustacean zooplankton, rotifer, and phytoplankton communities in a set of invaded and noninvaded reference lakes. The non‐native invertebrate predator Bythotrephes had significant effects on zooplankton community size structure, rotifers, and phytoplankton taxonomic composition, but no significant effects on crustacean zooplankton taxonomic and functional group composition. Part of the variation in phytoplankton communities was explained by the presence of the invader. Because Bythotrephes is generally known to be a carnivore and to not consume phytoplankton, this effect is likely mediated by the zooplankton community's response to environmental gradients. Although Bythotrephes appears to indirectly alter phytoplankton composition in invaded lakes, there was no evidence of a trophic cascade, and edible phytoplankton biovolume did not increase in invaded lakes. These complex direct and indirect interactions suggest that effects of invaders may be highly context‐dependent, and therefore pose a significant challenge for predicting wider community and ecosystem responses.
Effects of simultaneous climate change and geomorphic evolution on thermal characteristics of a shallow Alaskan lake
Authors: Griffiths Jennifer R. , Schindler Daniel E. , Balistrieri Laurie S. , Ruggerone Gregory T.
Published: December 2010

We used a hydrodynamics model to assess the consequences of climate warming and contemporary geomorphic evolution for thermal conditions in a large, shallow Alaskan lake. We evaluated the effects of both known climate and landscape change, including rapid outlet erosion and migration of the principal inlet stream, over the past 50 yr as well as future scenarios of geomorphic restoration. Compared to effects of air temperature during the past 50 yr, lake thermal properties showed little sensitivity to substantial (~60%) loss of lake volume, as the lake maximum depth declined from 6 m to 4 m driven by outlet erosion. The direction and magnitude of future lake thermal responses will be driven largely by the extent of inlet stream migration when it occurs simultaneously with outlet erosion. Maintaining connectivity with inlet streams had substantial effects on buffering lake thermal responses to warming climate. Failing to account for changing rates and types of geomorphic processes under continuing climate change may misidentify the primary drivers of lake thermal responses and reduce our ability to understand the consequences for aquatic organisms.
Scale‐dependent interactions of Mediterranean whales with marine dynamics
Authors: Cotte Cèdric , d'Ovidio Francesco , Chaigneau Alexis , Lèvy Marina , Taupier-Letage Isabelle , Mate Bruce , Guinet Christophe
Published: December 2010

We investigated the influence of the ocean circulation at different spatiotemporal scales on the seasonal distribution of a large marine predator, the Mediterranean fin whale, by comparing multisatellite data with the positions of eight fin whales equipped with Argos tracking devices from August 2003 to June 2004. At the western Mediterranean basin scale, fin whales were associated with the anticlockwise gyre in the northern part of the western Mediterranean Sea, which defines the habitat of krill, the whales' main prey. At mesoscale and submesoscale, and only during the seasonal phytoplankton biomass minimum in summer, whales exhibited a preference for the periphery of eddies and they were often associated with filaments indicative of submesoscale fronts. Timescales of these mesoscale and submesoscale features are comparable with the ecological timescales of the lower levels of the trophic chain. Whales were not associated to productive areas, probably due to the spatiotemporal lag between phytoplankton and krill. Our results suggest that stirring by eddies may create filaments that are favorable foraging grounds for predators searching for aggregated prey during the most oligotrophic period of the year.
Settlement of vegetative fragments of Ulva prolifera confirmed as an important seed source for succession of a large‐scale green tide bloom
Authors: Zhang Xiaowen , Xu Dong , Mao Yuze , Li Youxun , Xue Suyan , Zou Jian , Lian Wei , Liang Chengwei , Zhuang Zhimeng , Wang Qingyin , Ye Naihao
Published: December 2010

Ulva prolifera green tides in the Yellow Sea of China in the past 3 yr are among the largest macroalgal blooms ever recorded. Satellite images, as well as wind and current patterns, provide a clear picture of the formation of these green tides; however, their place of origin remains unclear. Terrestrial investigation along the coastline of the Jiangsu Province and two shipboard surveys in the Yellow Sea in 2009 showed that filamentous Ulvaceae algae were prevalent in various environments in Jiangsu Province including floating rafts for Porphyra cultivation, land‐based bivalve culturing ponds, estuaries, embankments, intertidal stones, wharfs, and hard muddy coasts. Vegetative fragments in sediment samples were found in both shipboard surveys during the bloom and postbloom periods, and all of the samples were U. prolifera. Phylogenetic analysis of 5S spacer sequences showed that the green tide in the Yellow Sea was not of terrestrial origin. However, settled vegetative fragments of U. prolifera were an important seed source for the successive and more serious green tide blooms.
Source, biogeochemical cycling, and fluorescence characteristics of dissolved organic matter in an agro‐urban estuary
Authors: Fellman Jason B. , Petrone Kevin C. , Grierson Pauline F.
Published: December 2010

Seasonal measurements of dissolved organic matter (DOM) fluorescence characteristics were combined with weekly to bi‐weekly measurements of carbon (C), nitrogen (N), and phosphorus (P) (including particulate, dissolved organic and inorganic forms) and chlorophyll to determine how riverine inputs and autochthonous production influence DOM and nutrient dynamics in the Swan‐Canning estuary, Western Australia. Estuarine concentrations of C, N, and P were influenced by multiple factors, including the seasonal riverine flux of DOM, N, and P, the regeneration of mainly inorganic N and P from benthic anoxia, and the delivery of DOM and nutrients from urban drains. Parallel factor analysis of excitation‐emission matrices identified eight fluorescence components that were used to fingerprint three distinct sources of estuarine DOM: (1) riverine DOM derived mainly from vascular plant material, (2) autochthonous DOM recently produced within the estuary (indicated by tryptophan‐like fluorescence), and (3) autochthonous DOM originating from within the lower estuary or coastal marine environment enriched in marine humic‐like and tyrosine‐like fluorescence. Overall, fluorescence DOM characteristics shifted from humic‐like in the upper and mid‐estuary to protein‐like in the lower estuary, which likely reflects the increased contribution of autochthonous relative to terrigenous DOM closer to the estuary mouth. Our findings show that DOM composition varies with season and estuary position as riverine DOM inputs, mainly from terrestrial plant material, are supplemented by autochthonous DOM contributions associated with discrete inputs of inorganic nutrients.
Contrasting patterns of cadmium bioaccumulation in freshwater cladocerans
Authors: Tan Qiao-Guo , Wang Wen-Xiong
Published: December 2010

We investigated the patterns of cadmium (Cd) bioaccumulation in three freshwater cladocerans with contrasting calcium (Ca) contents and Ca uptake and loss kinetics. Ca content and dissolved Cd uptake rate were significantly correlated. The large interspecies differences in sensitivity to aqueous Cd exposure were explained by the differences in the Cd uptake rate. The high‐Ca species, Daphnia galeata and Ceriodaphnia dubia, had higher dissolved Cd uptake rates and were more sensitive to aqueous Cd exposure than the low‐Ca species, Moina macrocopa. Food was the dominant Cd source for all of the cladocerans. Feeding on the same Cd‐containing food, M. macrocopa attained the highest Cd body concentration due to its higher assimilation efficiency and ingestion rate, which led to its susceptibility to dietary Cd despite its relatively high intrinsic tolerance. C. dubia suffered most from the dietary Cd exposure, probably due to its higher intrinsic sensitivity. The efflux of Cd from the cladocerans was well described by a two‐compartment model. Although the efflux rate constants from both compartments were comparable among the species, D. galeata had a much higher proportion of the internalized Cd distributed into the fast compartment, and thus eliminated Cd at a much faster rate. The diversity of Cd bioaccumulation patterns in cladocerans indicates that no simple generalization can be made from data on only a few species. Because cladocerans are often the major zooplankton in lakes, their contrasting Cd accumulation and loss suggest that the biogeochemistry of Cd would be different in waters dominated by different cladocerans.
Differences in phosphorus demand among detritivorous chironomid larvae reflect intraspecific adaptations to differences in food resource stoichiometry across lowland tropical streams
Authors: Small Gaston E. , Wares John P. , Pringle Catherine M.
Published: December 2010

We tested whether assemblages of detritivorous chironomid larvae (Chironomidae: Diptera) varied in phosphorus (P) demand based on local nutrient conditions using a series of streams in lowland Costa Rica that exhibit a natural range in ambient dissolved P and detrital P due to inputs of solute‐rich groundwater. Chironomids collected from three high‐P streams had growth rates and P‐excretion rates that were similar to, or lower than, those of chironomids collected from four low‐P streams. Chironomids from a naturally low‐P stream that was experimentally amended with P over 8 yr showed an increase in P‐excretion rates but not growth rates, indicating an inability of these chironomids to use additional dietary P. Chironomids from a high‐P stream showed greater evidence of P limitation (lower growth rates, P‐excretion rates, and ribonucleic acid content) when fed low‐P detritus compared to chironomids from a low‐P stream. Our findings support the hypothesis that chironomid assemblages are adapted to local food quality in this heterogeneous landscape, thereby circumventing P limitation. Genetic analysis indicates that chironomid assemblages across the study streams are similar in species composition, suggesting that differences in P demand may be due to microevolution. The lower P demand among chironomids from low‐P streams appears to limit their ability to respond to nutrient‐enriched food, effectively stabilizing the food web in response to changes in nutrient availability.
Dissimilatory reduction of nitrate to ammonium, not denitrification or anammox, dominates benthic nitrate reduction in tropical estuaries
Authors: Dong Liang F. , Sobey Milika Naqasima , Smith Cindy J. , Rusmana Iman , Phillips Wayne , Stott Andrew , Osborn A. Mark , Nedwell David B.
Published: December 2010

We measured benthic denitrification (DN) and dissimilatory reduction of nitrate to ammonium (DNRA) using the isotope‐pairing technique in three tropical estuaries in Thailand (Mae Klong), Indonesia (Cisadane), and Fiji (Vunidawa‐Rewa) during rainy, dry, and intermediate seasons along the salinity gradient of each estuary. DNRA dominated. Anammox (AN) was measured initially but neither AN activity nor AN bacteria‐related 16S ribosomal RNA genes were detected in any of the estuaries. DN was either zero or extremely low, driven by water column nitrate and not from benthic nitrification‐DN. N2O was not formed during DN. N2O saturations in estuary water were low, except in the nutrified Indonesian estuary, and tropical estuaries are therefore likely to be only small sources of N2O. Benthic nitrate reduction was nitrate limited; when nitrate was enhanced experimentally, DN increased slightly, but DNRA increased proportionately much more. Predominance of DNRA over DN in tropical estuaries may be due both to an energetic advantage (greater standard free energy change, ΔG°) of nitrate ammonifiers over denitrifiers when competing for limited nitrate, and also to higher affinity for nitrate by the nitrate ammonifiers. At tropical temperatures the three processes occur in the order DNRA > DN > AN. In contrast, temperate estuaries, at lower temperature and higher nitrate concentrations, exhibit proportionately greater levels of AN and DN. The Cisadane estuary became anoxic during the dry season, with high ammonium and sulfide, but no nitrate reduction because of lack of nitrate. Addition of nitrate stimulated high rates of autotrophic DN driven by sulfide, but not DNRA.
Analysis of CO in the tropical troposphere using Aura satellite data and the GEOS-Chem model: insights into transport characteristics of the GEOS meteorological products
Authors:   Junhua Liu, Logan J. A. , Jones D. B. A. , Livesey N. J. , Megretskaia I. , Carouge C. , Nedelec P.
Published: December 2010

Abstract. We use the GEOS-Chem chemistry-transport model (CTM) to interpret the spatial and temporal variations of tropical tropospheric CO observed by the Microwave Limb Sounder (MLS) and the Tropospheric Emission Spectrometer (TES). In so doing, we diagnose and evaluate transport in the GEOS-4 and GEOS-5 assimilated meteorological fields that drive the model, with a particular focus on vertical mixing at the end of the dry season when convection moves over the source regions. The results indicate that over South America, deep convection in both GEOS-4 and GEOS-5 decays at too low an altitude early in the wet season, and the source of CO from isoprene in the model (MEGAN v2.1) is too large, causing a lag in the model's seasonal maximum of CO compared to MLS CO in the upper troposphere (UT). TES and MLS data reveal problems with excessive transport of CO to the eastern equatorial Pacific and lofting in the ITCZ in August and September, particularly in GEOS-4. Over southern Africa, GEOS-4 and GEOS-5 simulations match the phase of the observed CO variation from the lower troposphere (LT) to the UT fairly well, although the magnitude of the seasonal maximum is underestimated considerably due to low emissions in the model. A sensitivity run with increased emissions leads to improved agreement with observed CO in the LT and middle troposphere (MT), but the amplitude of the seasonal variation is too high in the UT in GEOS-4. Difficulty in matching CO in the LT and UT implies there may be overly vigorous vertical mixing in GEOS-4 early in the wet season. Both simulations and observations show a time lag between the peak in fire emissions (July and August) and in CO (September and October). We argue that it is caused by the prevailing subsidence in the LT until convection moves south in September, as well as the low sensitivity of TES data in the LT over the African Plateau. The MLS data suggest that too much CO has been transported from fires in northern Africa to the UT in the model during the burning season, as does MOZAIC aircraft data, perhaps as a result of the combined influence of too strong Harmattan winds in the LT and too strong vertical mixing over the Gulf of Guinea in the model.