North Pacific freshwater events linked to changes in glacial ocean circulation.

There is compelling evidence that episodic deposition of large volumes of freshwater into the oceans strongly influenced global ocean circulation and climate variability during glacial periods1,2. In the North Atlantic region, episodes of massive freshwater discharge to the North Atlantic Ocean were related to distinct cold periods known as Heinrich Stadials1-3. By contrast, the freshwater history of the North Pacific region remains unclear, giving rise to persistent debates about the existence and possible magnitude of climate links between the North Pacific and North Atlantic oceans during Heinrich Stadials4,5. Here we find that there was a strong connection between changes in North Atlantic circulation during Heinrich Stadials and injections of freshwater from the North American Cordilleran Ice Sheet to the northeastern North Pacific. Our record of diatom δ18O (a measure of the ratio of the stable oxygen isotopes 18O and 16O) over the past 50,000 years shows a decrease in surface seawater δ18O of two to three per thousand, corresponding to a decline in salinity of roughly two to four practical salinity units. This coincided with enhanced deposition of ice-rafted debris and a slight cooling of the sea surface in the northeastern North Pacific during Heinrich Stadials 1 and 4, but not during Heinrich Stadial 3. Furthermore, results from our isotope-enabled model6 suggest that warming of the eastern Equatorial Pacific during Heinrich Stadials was crucial for transmitting the North Atlantic signal to the northeastern North Pacific, where the associated subsurface warming resulted in a discernible freshwater discharge from the Cordilleran Ice Sheet during Heinrich Stadials 1 and 4. However, enhanced background cooling across the northern high latitudes during Heinrich Stadial 3-the coldest period in the past 50,000 years7-prevented subsurface warming of the northeastern North Pacific and thus increased freshwater discharge from the Cordilleran Ice Sheet. In combination, our results show that nonlinear ocean-atmosphere background interactions played a complex role in the dynamics linking the freshwater discharge responses of the North Atlantic and North Pacific during glacial periods.

Deglacial pulses of deep-ocean silicate into the subtropical North Atlantic Ocean.

Growing evidence suggests that the low atmospheric CO2 concentration of the ice ages resulted from enhanced storage of CO2 in the ocean interior, largely as a result of changes in the Southern Ocean. Early in the most recent deglaciation, a reduction in North Atlantic overturning circulation seems to have driven CO2 release from the Southern Ocean, but the mechanism connecting the North Atlantic and the Southern Ocean remains unclear. Biogenic opal export in the low-latitude ocean relies on silicate from the underlying thermocline, the concentration of which is affected by the circulation of the ocean interior. Here we report a record of biogenic opal export from a coastal upwelling system off the coast of northwest Africa that shows pronounced opal maxima during each glacial termination over the past 550,000 years. These opal peaks are consistent with a strong deglacial reduction in the formation of silicate-poor glacial North Atlantic intermediate water (GNAIW). The loss of GNAIW allowed mixing with underlying silicate-rich deep water to increase the silicate supply to the surface ocean. An increase in westerly-wind-driven upwelling in the Southern Ocean in response to the North Atlantic change has been proposed to drive the deglacial rise in atmospheric CO2 (refs 3, 4). However, such a circulation change would have accelerated the formation of Antarctic intermediate water and sub-Antarctic mode water, which today have as little silicate as North Atlantic Deep Water and would have thus maintained low silicate concentrations in the Atlantic thermocline. The deglacial opal maxima reported here suggest an alternative mechanism for the deglacial CO2 release. Just as the reduction in GNAIW led to upward silicate transport, it should also have allowed the downward mixing of warm, low-density surface water to reach into the deep ocean. The resulting decrease in the density of the deep Atlantic relative to the Southern Ocean surface promoted Antarctic overturning, which released CO2 to the atmosphere.

First record of Halocercus sp. (Pseudaliidae) lungworm infections in two stranded neonatal orcas (Orcinus orca).

Orca (Orcinus orca) strandings are rare and post-mortem examinations on fresh individuals are scarce. Thus, little is known about their parasitological fauna, prevalence of infections, associated pathology and the impact on their health. During post-mortem examinations of two male neonatal orcas stranded in Germany and Norway, lungworm infections were found within the bronchi of both individuals. The nematodes were identified as Halocercus sp. (Pseudaliidae), which have been described in the respiratory tract of multiple odontocete species, but not yet in orcas. The life cycle and transmission pathways of some pseudaliid nematodes are incompletely understood. Lungworm infections in neonatal cetaceans are an unusual finding and thus seem to be an indicator for direct mother-to-calf transmission (transplacental or transmammary) of Halocercus sp. nematodes in orcas.

Isolation and characterization of eight microsatellite loci in the brook lamprey Lampetra planeri (Petromyzontiformes) using 454 sequence data.

Eight polymorphic microsatellite loci were developed for the brook lamprey Lampetra planeri through 454 sequencing and their usefulness was tested in 45 individuals of both L. planeri and the river lamprey Lampetra fluviatilis. The number of alleles per loci ranged between two and five; the Italian and Irish populations had a mean expected heterozygosity of 0·388 and 0·424 and a mean observed heterozygosity of 0·418 and 0·411, respectively.

A question of time: the land snail Murella muralis (Gastropoda: Pulmonata) reveals constraints on past ecological speciation.

The lively debate about speciation currently focuses on the relative importance of factors driving population differentiation. While many studies are increasingly producing results on the importance of selection, little is known about the interaction between drift and selection. Moreover, there is still little knowledge on the spatial-temporal scales at which speciation occurs, that is, arrangement of habitat patches, abruptness of habitat transitions, climate and habitat changes interacting with selective forces. To investigate these questions, we quantified variation on a fine geographical scale analysing morphological (shell) and genetic data sets coupled with environmental data in the land snail Murella muralis, endemic to the Mediterranean island of Sicily. Analysis of a fragment of the mitochondrial DNA cytochrome oxidase I gene (COI) and eight nuclear microsatellite loci showed that genetic variation is highly structured at a very fine spatial scale by local palaeogeographical events and historical population dynamics. Molecular clock estimates, calibrated here specifically for Tyrrhenian land snails, provided a framework of palaeogeographical events responsible for the observed geographical variations and migration routes. Finally, we showed for the first time well-documented lines of evidence of selection in the past, which explains divergence of land snail shell shapes. We suggest that time and palaeogeographical history acted as constraints in the progress along the ecological speciation continuum. Our study shows that testing for correlation among palaeogeography, morphology and genetic data on a fine geographical scale provides information fundamental for a detailed understanding of ecological speciation processes.

Microsatellite usefulness is independent of phylogenetic distance in Tyrant flycatchers (Aves: Tyrannidae): a test using two globally threatened species.

Tyrant flycatchers (Aves: Tyrannidae) are endemic to the New World, and many species of this group are threatened or near-threatened at the global level. The aim of this study was to test the 18 microsatellite markers that have been published for other Tyrant flycatchers in the Strange-tailed Tyrant (Alectrurus risora) and the Sharp-tailed Tyrant (Culicivora caudacuta), two endemic species of southern South American grasslands that are classified as vulnerable. We also analyzed the usefulness of loci in relation to phylogenetic distance to the source species. Amplification success was high in both species (77 to 83%) and did not differ between the more closely and more distantly related species to the source species. Polymorphism success was also similar for both species, with 9 and 8 loci being polymorphic, respectively. An increased phylogenetic distance thus does not gradually lead to allelic or locus dropouts, implying that in Tyrant flycatchers, the published loci are useful independent of species relatedness.

Mitochondrial genomes of the freshwater monogonont rotifer Brachionus fernandoi and of two additional B. calyciflorus sensu stricto lineages from Germany and the USA (Rotifera, Brachionidae).

The Brachionus calyciflorus species complex was recently subdivided into four species, but genetic resources to resolve phylogenetic relationships within this complex are still lacking. We provide two complete mitochondrial (mt) genomes from B. calyciflorus sensu stricto (Germany, USA) and the mt coding sequences (cds) from a German B. fernandoi. Phylogenetic analysis placed our B. calyciflorus sensu stricto strains close to the published genomes of B. calyciflorus, forming the putative sister species to B. fernandoi. Global representatives of B. calyciflorus sensu stricto (i.e. Europe, USA, and China) are genetically closer related to each other than to B. fernandoi (average pairwise nucleotide diversity 0.079 intraspecific vs. 0.254 interspecific).

Variation in heat shock protein 40 kDa relates to divergence in thermotolerance among cryptic rotifer species.

Genetic divergence and the frequency of hybridization are central for defining species delimitations, especially among cryptic species where morphological differences are merely absent. Rotifers are known for their high cryptic diversity and therefore are ideal model organisms to investigate such patterns. Here, we used the recently resolved Brachionus calyciflorus species complex to investigate whether previously observed between species differences in thermotolerance and gene expression are also reflected in their genomic footprint. We identified a Heat Shock Protein gene (HSP 40 kDa) which exhibits cross species pronounced sequence variation. This gene exhibits species-specific fixed sites, alleles, and sites putatively under positive selection. These sites are located in protein binding regions involved in chaperoning and may therefore reflect adaptive diversification. By comparing three genetic markers (ITS, COI, HSP 40 kDa), we revealed hybridization events between the cryptic species. The low frequency of introgressive haplotypes/alleles suggest a tight, but not fully impermeable boundary between the cryptic species.

The superantigen streptococcal pyrogenic exotoxin C (SPE-C) exhibits a novel mode of action.

Recombinant streptococcal pyrogenic exotoxin C (SPE-C) is a potent superantigen that stimulates Vbeta2-bearing human T cells, but is inactive in mice. SPE-C binds with high affinity to both human HLA-DR and murine I-E molecules, but not to murine I-A molecules in a zinc-dependent fashion. Competition binding studies with other recombinant toxins revealed that SPE-C lacks the generic low affinity major histocompatibility complex (MHC) class II alpha-chain binding site common to all other bacterial superantigens. Despite this, SPE-C cross-links MHC class II to induce homotypic aggregation of class II-bearing B cells. Nondenaturing sodium dodecyl sulfate electrophoresis and size exclusion chromatography revealed that both wild-type and recombinant SPE-C exist in a stable dimer at neutral or alkaline pH. These data support a recent crystal structure of SPE-C and reveal yet another mechanism by which bacterial superantigens ligate and cross-link MHC class II.

Staphylococcal enterotoxin A has two cooperative binding sites on major histocompatibility complex class II.

The superantigen staphylococcal enterotoxin A (SEA) binds to major histocompatibility complex (MHC) class II molecules at two sites on either side of the peptide groove. Two separate but cooperative interactions to the human class II molecule HLA-DR1 were detected. The first high affinity interaction to the DR1 beta chain is mediated by a zinc atom coordinated by H187, H225, and D227 in SEA and H81 in the polymorphic DR1 beta chain. The second low affinity site is to the DR1 alpha chain analogous to SEB binding and is mediated by residue F47 in SEA. Binding of one SEA to the DR1 beta chain enhances the binding of a second SEA molecule to the DR1 alpha chain. The zinc site is on the opposite side of the SEA molecule from residue F47 so that one SEA molecule can readily bind two class II molecules. Both binding sites on SEA are required for maximal activity. Thus, unlike, SEB, SEA requires two separate binding sites for optimal activity, which may allow it to stabilize SEA interaction with T cell receptors, as well as to activate the antigen-presenting cell by cross-linking MHC class II.

Evolutionary implications of discordant clines across the Baltic Mytilus hybrid zone (Mytilus edulis and Mytilus trossulus).

It is well established that reproductive isolation often arises from genome incompatibilities and that genes encoding reproductive traits are less prone to introgression. Hybrid zones of Mytilus trossulus and Mytilus edulis provide an intriguing model to assess reproductive isolation. Although gene flow is restricted in North America, introgression is pervasive in the Baltic. This study aimed at analyzing the shape of multilocus clines across the Baltic contact zone between M. edulis and M. trossulus to infer mechanisms of restriction to gene flow. We use maximum likelihood methods to construct the best fitting individual clines for five markers located on biparentally inherited autosomes and paternally and maternally inherited mitochondrial DNA (mtDNA). Strong cline shape differences among markers suggest that reproductive isolation arising from genome-wide incompatibilities is weak, and that these discrepancies possibly result from genetic drift, hybrid zone movement or marker-specific selection. However, the finding of a common cline center for M7 lysin (involved in fertilization) and paternally transmitted mtDNA (causing nuclear-mitochondrial incompatibilities in hybrids) suggest that these loci may play a role in incomplete reproductive isolation.

Enhanced North Pacific deep-ocean stratification by stronger intermediate water formation during Heinrich Stadial 1.

The deglacial history of CO2 release from the deep North Pacific remains unresolved. This is due to conflicting indications about subarctic Pacific ventilation changes based on various marine proxies, especially for Heinrich Stadial 1 (HS-1) when a rapid atmospheric CO2 rise occurs. Here, we use a complex Earth System Model to investigate the deglacial North Pacific overturning and its control on ocean stratification. Our results show an enhanced intermediate-to-deep ocean stratification coeval with intensified North Pacific Intermediate Water (NPIW) formation during HS-1, compared to the Last Glacial Maximum. The stronger NPIW formation causes lower salinities and higher temperatures at intermediate depths. By lowering NPIW densities, this enlarges vertical density gradient and thus enhances intermediate-to-deep ocean stratification during HS-1. Physically, this process prevents the North Pacific deep waters from a better communication with the upper oceans, thus prolongs the existing isolation of glacial Pacific abyssal carbons during HS-1.

Radiocarbon constraints on the extent and evolution of the South Pacific glacial carbon pool.

During the last deglaciation, the opposing patterns of atmospheric CO2 and radiocarbon activities (Δ(14)C) suggest the release of (14)C-depleted CO2 from old carbon reservoirs. Although evidences point to the deep Pacific as a major reservoir of this (14)C-depleted carbon, its extent and evolution still need to be constrained. Here we use sediment cores retrieved along a South Pacific transect to reconstruct the spatio-temporal evolution of Δ(14)C over the last 30,000 years. In ∼2,500-3,600 m water depth, we find (14)C-depleted deep waters with a maximum glacial offset to atmospheric (14)C (ΔΔ(14)C=-1,000‰). Using a box model, we test the hypothesis that these low values might have been caused by an interaction of aging and hydrothermal CO2 influx. We observe a rejuvenation of circumpolar deep waters synchronous and potentially contributing to the initial deglacial rise in atmospheric CO2. These findings constrain parts of the glacial carbon pool to the deep South Pacific.

Early relapse after single auto-SCT for multiple myeloma is a major predictor of survival in the era of novel agents.

The role of auto-SCT in the treatment of multiple myeloma (MM) in the era of novel agents continues to evolve. It is now clear that the depth of response and clinical outcomes have significantly improved as a result of the combination of these strategies. However, not all patients with MM who undergo auto-SCT are able to sustain a meaningful response and 20% of patients relapse shortly after auto-SCT. In this study, we aimed to assess the impact of early relapse (ER) after auto-SCT on OS for MM patients undergoing single auto-SCT who had received novel agent-based induction regimens. All consecutive patients with MM undergoing single auto-SCT from January 2002 to September 2012 who had novel induction therapy were evaluated. A total of 184 patients were identified. The median OS and PFS for the group of transplanted patients were 93 and 25.4 months, respectively. Median time to relapse was 17.2 months with 40% having relapsed at the time of analysis. ER (<12 months post auto-SCT) was seen in 27 (36%) out of 75 patients who had relapsed, and median OS was significantly shorter than in those with non-ER. Multivariate analysis showed ER as the major independent prognostic factor for OS. On the basis of these findings, we conclude that not only attainment of a good response, but sustainability of it, appears to be a major prognostic variable in MM in the era of novel therapy. Patients with ER post auto-SCT should biologically be characterized in prospective studies to better understand the mechanisms of resistance associated with this particular entity.

Efficacy, toxicity and mortality of autologous SCT in multiple myeloma patients with dialysis-dependent renal failure.

Numerous studies have reported the feasibility and safety of autologous SCT (ASCT) in patients with multiple myeloma (MM) and mild to moderate renal impairment, but there are limited data in dialysis-dependent patients. In this retrospective study, we reviewed the toxicities and efficacy outcomes of 33 MM patients with dialysis-dependent renal failure who underwent ASCT at our institution from 1998 to 2012. The most common grade 3 non-hematologic toxicities were mucositis (49%), infection (15%) and bleeding (6%). Atrial dysrhythmias (24%) and delirium (30%) of all grades were also common. Hematologic toxicities included febrile neutropenia (88%); and RBC and platelet transfusions were required by 71 and 100% of patients, respectively. Transplant-related mortality (TRM) was high at 15%, predominantly caused by septic shock. Response to ASCT was at least VGPR (very good PR) in 50%, PR in 46.2% and stable disease (SD) in 3.8%. Median OS was 5.6 years, comparable to our overall institutional data. Overall, seven patients became dialysis independent. We conclude that ASCT can be an effective treatment for dialysis-dependent MM patients, with high response rates and survival. However, toxicities and a high TRM are observed indicating that further studies are needed to enhance the safety of this approach.

CyBorD induction therapy in clinical practice.

Cyclophosphamide, bortezomib and dexamethasone (CyBorD) is a highly active three-drug induction regimen for untreated transplant-eligible multiple myeloma patients. Although CyBorD has been evaluated only in the phase 2 setting in a limited number of patients, its high efficacy and ease of administration have led to its widespread use. Given that clinical trial efficacy can overestimate real-life effectiveness, we reviewed our institutional experience with 109 newly diagnosed patients who were treated with CyBorD in a non-clinical trial setting. After a median of four cycles, overall response rate (ORR) and very good partial response rate or better (⩾VGPR) were 95 and 66%, respectively, comparable to phase 2 studies of CyBorD and other three/four-drug induction regimens. All patients subsequently underwent successful stem cell collection and upgraded responses to ORR 98% and ⩾VGPR 79% post transplant. At a median follow-up of 19.8 months after diagnosis, the 2-year OS probability was 95.3% (95%CI: 89-98). The presence of concurrent plasmacytoma at diagnosis was the only prognostic factor predicting poorer survival (HR=5.56; 95%CI: 0.92-33.74; P=0.03). CyBorD was well-tolerated, with no severe peripheral neuropathy and minimal hematologic toxicity. Therefore, CyBorD is a convenient, well-tolerated, highly effective induction regimen in preparation for autologous SCT in real-life clinical practice.

Myzostomida: a link between trochozoans and flatworms?

Myzostomids are obligate symbiotic invertebrates associated with echinoderms with a fossil record that extends to the Ordovician period. Due to their long history as host-specific symbionts, myzostomids have acquired a unique anatomy that obscures their phylogenetic affinities to other metazoans: they are incompletely segmented, parenchymous, acoelomate organisms with chaetae and a trochophore larva. Today, they are most often classified within annelids either as an aberrant family of polychaetes or as a separate class. We inferred the phylogenetic position of the Myzostomida by analysing the DNA sequences of two slowly evolving nuclear genes: the small subunit ribosomal RNA and elongation factor-1alpha. All our analyses congruently indicated that myzostomids are not annelids but suggested instead that they are more closely related to flatworms than to any trochozoan taxon. These results, together with recent analyses of the myzostomidan ultrastructure, have significant implications for understanding the evolution of metazoan body plans, as major characters (segmentation, coeloms, chaetae and trochophore larvae) might have been independently lost or gained in different animal phyla.

Thoracoscopy for spontaneous pneumothorax 2.10 version with bleb stapling and pleurectomy.

A series of 25 Thoracoscopy procedures were performed for spontaneous pneumothorax over the past 2 1/2 years. The indications for the procedure were recurrent pneumothorax or choice of patient for definitive care. The procedure developed over the period of 2 1/2 years, and the procedure included a thoracoscopy, stapling of apical blebs, and apical pleurectomy. The complication rate was 3% and limited to local wound problems. There was one recurrent pneumothorax in a patient who did not have the pleurectomy as a part of the procedure. This was early on in the experience, when it was felt that pleural abrasion would be adequate. Since that time, a formal apical pleurectomy has been done with each of these procedures. No further recurrences have been noted over the 2 1/2 year period of time. The procedure includes one port at the anterior axillary line, fifth intercostal space, one port in the axilla, third intercostal space, and one port in the midclavicular line, fourth intercostal space. A 30 degree and angled scope is sometimes used for better visualization. The Endo GIA (US Surgical or equivalent Ethicon stapler) is used to staple the blebs, and the pleurectomy is done through the two non-video ports.

BCL-2 family proteins as 5-Azacytidine-sensitizing targets and determinants of response in myeloid malignancies.

Synergistic molecular vulnerabilities enhancing hypomethylating agents in myeloid malignancies have remained elusive. RNA-interference drug modifier screens identified antiapoptotic BCL-2 family members as potent 5-Azacytidine-sensitizing targets. In further dissecting BCL-XL, BCL-2 and MCL-1 contribution to 5-Azacytidine activity, siRNA silencing of BCL-XL and MCL-1, but not BCL-2, exhibited variable synergy with 5-Azacytidine in vitro. The BCL-XL, BCL-2 and BCL-w inhibitor ABT-737 sensitized most cell lines more potently compared with the selective BCL-2 inhibitor ABT-199, which synergized with 5-Azacytidine mostly at higher doses. Ex vivo, ABT-737 enhanced 5-Azacytidine activity across primary AML, MDS and MPN specimens. Protein levels of BCL-XL, BCL-2 and MCL-1 in 577 AML patient samples showed overlapping expression across AML FAB subtypes and heterogeneous expression within subtypes, further supporting a concept of dual/multiple BCL-2 family member targeting consistent with RNAi and pharmacologic results. Consequently, silencing of MCL-1 and BCL-XL increased the activity of ABT-199. Functional interrogation of BCL-2 family proteins by BH3 profiling performed on patient samples significantly discriminated clinical response versus resistance to 5-Azacytidine-based therapies. On the basis of these results, we propose a clinical trial of navitoclax (clinical-grade ABT-737) combined with 5-Azacytidine in myeloid malignancies, as well as to prospectively validate BH3 profiling in predicting 5-Azacytidine response.