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An AM2 model modification is proposed by including the parameter identification and a robust feedback control synthesis. The contribution is shown by experimental proof-of-concept. The AM2 model is modified with the aim of including the CODs changes in the effluent near the steady state with the inlet CODt concentration changes at a fixed flow rate. The parameter identification is experimentally implemented on-line and computationally performed via the Levenberg–Marquardt algorithm. To this end, an experimental set-up was carried out each from a two-stage biomethane production process stage as an instrumented and automated bioreactor. Afterward, robust feedback control is implemented for each stage. For the first stage, the VFA productivity maximum is defined as the control goal whereas the biomethane maximum flow is the aim on the second stage. The feedback control is robust against kinetics and parametric uncertainties such that the biogas production reaches biomethane maximum production. In this sense, the contribution shows the biomethane production can be optimized through enzymatic agave bagasse hydrolysate. • Biogas yielding via enzymatic hydrolysate of agave bagasse needs model modification. • A modified model renders an accurate structure for kinetics parameter identification. • A robust feedback control allows us to enhance the biomethane production. • An experimental benchmark shows the concept of enhancing biomethane production. [ABSTRACT FROM AUTHOR]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.dsr.2005.03.001 Byline: J. Ruelas-Inzunza (a), F. Paez-Osuna (b), Luis A. Soto (c) Keywords: Trace metals; Riftia pachyptila; Bioaccumulation; Mexico; Guaymas basin Abstract: Twenty two specimens of vestimentiferan tube worms Riftia pachyptila were collected from Guaymas Basin. The distribution of ten trace metals in trophosome and vestimentum was investigated. Highest mean concentrations of Co, Cu and Fe were detected in the trophosome; while higher mean levels of Cd, Hg, Mn, Ni, Pb and Zn were measured in the vestimentum. However, the t-student test resulted in significant differences (p Author Affiliation: (a) Technological Institute of the Sea, P.O. Box 757, Mazatlan, 82000 Sinaloa, Mexico (b) Institute of Marine Sciences and Limnology, National Autonomous University of Mexico, P.O. Box 811, Mazatlan, 82000 Sinaloa, Mexico (c) Institute of Marine Sciences and Limnology, National Autonomous University of Mexico, P.O. Box 70-153, Mexico city 04510, Mexico Article History: Received 23 February 2004; Revised 22 November 2004; Accepted 3 March 2005

The vent environments are metal rich because of the presence of extensive sulfide deposits and precipitation of metal sulphideEs like iron, nickel, copper, zinc, cadmium and mercury. Inspite of the tremendous amounts of metals occurring in this species, no deleterious effects were recognizable.

Highlights • Caldicellulosiruptor spp. produced 134 mmol H 2 /L from wheat straw hydrolysate. • Side stream of H 2 production used as C source for PHB synthesis by R. eutropha. • Highest PHB content of ∼83% was obtained at 20% aeration and nitrogen depletion. • 41.5% of carbon and 51.9% of electrons used for PHB production in coupled process. Abstract This report presents an integrated biorefinery concept in which wheat straw hydrolysate was treated with co-cultures of osmotolerant thermophilic bacterial strains, Caldicellulosiruptor saccharolyticus and C. owensensis to obtain hydrogen, while the liquid effluent containing acetate and residual glucose was used as feed for polyhydroxybutyrate (PHB) production by Ralstonia eutropha. The Caldicellulosiruptor spp. co-culture consumed 10.8 g/L of pretreated straw sugars, glucose and xylose, producing 134 mmol H 2 /L. PHB accumulation by R. eutropha was first studied in minimal salts medium using acetate with/without glucose as carbon source. Addition of salts promoted cell growth and PHB production in the effluent. Fed-batch cultivation in a nitrogen limited medium with 40% (v/v) aeration resulted in a cell density of 15.1 g/L with PHB content of 80.1% w/w and PHB concentration of 12.1 g/L, while 20% aeration gave a cell density of 11.3 g/L with 83.4% w/w PHB content and 9.4 g/L PHB concentration. [ABSTRACT FROM AUTHOR]

The functional diversity of fungi remains poorly explored in the deep-sea, particularly in hydrothermal vents. Here, we approached this gap through the analysis of stable isotopes of carbon (δ13C), nitrogen (δ15N), and sulfur (δ34S) of fourteen isolates obtained from three deep-sea vent systems of the southern Gulf of California. The δ13C results indicated that 60% of the isolates relied on mixed carbon sources fixed by the Calvin-Benson-Bassham and the reductive Tricarboxylic Acid (rTCA) cycles, whereas 40% relied exclusively on rTCA carbon. The δ15N and δ34S values suggested a dependence on local and external nitrogen sources and the assimilation of chemosynthetic and photosynthetic inputs. Fungal δ13C and δ15N overlapped with those of primary and secondary vent macroconsumers, implying the assimilation of bacterial and invertebrate necromass and their ecological role as parasites. These findings provide insights into the unexplored trophic versatility of fungi in chemosynthetic ecosystems, highlighting their importance in deep-sea trophic dynamics. • First report of C, N, and S isotopes in fungi from deep-sea hydrothermal vents. • The 57% of the isolates relied on carbon sources fixed by the CBB and rTCA cycles. • The fungal δ15N indicated their dependence on local and external nitrogen sources. • The δ34S values implied the assimilation of chemosynthetic and photosynthetic inputs. • The δ13C and δ15N of fungi overlapped with primary and secondary vent macroconsumers. [ABSTRACT FROM AUTHOR]

The presence and abundance of particular nematode genera in marine sediments are bioindicators of environmental disturbance. They can even reveal the existence of specific toxicants, such as trace-metals and hydrocarbons derived from fossil fuels. We studied this important infaunal component during a three-year monitoring program in Mexico’s Exclusive Economic Zone (EEZ) in the aftermath of a major oil spill in the northern Gulf of Mexico caused by the sinking of the Deepwater Horizon platform ( DWH ) in April of 2010. A closer look at the nematode composition and density values throughout and after the DWH oil spill revealed considerable changes. Continental shelf and upper slope sediments sampled in the summer of 2010 included 48 genera and a density of 44.45 ind/10 cm −2 . Eight months later in the winter of 2011, there was a critical decrement in genera number (23) and density (25.22 ind/10 cm −2 ). However, in 2012, the nematode community showed signs of recovery: genus diversity was 58 with a density of 91.45 ind/10 cm −2 . Significant differences were recorded between the first and the last sampling periods, driven by a remarkable turn-over in genera composition, and by an increase in density of the genera Sabatieria , Dorylaimopsis, and Cheironchus . Similarly, significant spatial differences between the nematofauna of the inner-middle shelf and the deepest zone (>2000 m) were detected. Correlation analyses confirmed the tolerant behavior of the above genera to Ni and Co, and their proliferation when hydrocarbon compounds presumably derived from the DWH oil spill increased throughout the study. The Maturity Index (MI) estimated for each survey ranged from 2.35 to 2.6. Environmental Quality Status conditions in the summer of 2010 were good while in the winter of 2011 were poor, and moderate towards the winter of 2012. Index of Trophic Diversity (ITD) values for each survey were high: 0.70, 0.68, and 0.74, respectively. A high predominance of feeding guilds 1B and 2B was recorded throughout the study. The estimated Index of Trophic Diversity (ITD) values resulted high (Table 5). These values apparently indicated that the four feeding types were proportionally distributed in the nematode assemblage. This fact was better reflected during the winter of 2012. Nonetheless, these results are not congruent with the high predominance of feeding guilds 1B and 2B observed throughout the study. [ABSTRACT FROM AUTHOR]

A 3-year research program was undertaken to assess potential environmental disturbance caused by the Deepwater Horizon oil spill to the soft-bottom macrobenthic communities within Mexican waters of the northwestern Gulf of Mexico. Community properties and temporal/spatial variability were analyzed besides toxicant parameters such as hydrocarbons and trace-metals. Overall infaunal density increased, taxa proportion changed, and small-size opportunistic organisms prevailed throughout the study. Annual abundance-biomass comparison (ABC) curves revealed progressive stress scenarios from moderate to severe. Concentrations of vanadium, nickel, cobalt, PAHs and AHs increased gradually over time. However, low correlations between benthic density and biogeochemical variables were determined. Initially, sedimentary properties were the main drivers of benthic community structure; subsequently, nickel, vanadium and PAHs, indicative of anthropogenic effect, were highlighted. Interannual variability in the macroinfauna was attributed to the synergy of several environmental factors. Undoubtedly, compounds derived from fossil fuels had a significant disturbance role, but their source remains uncertain. [ABSTRACT FROM AUTHOR]

A myographic study was performed to compare the neuromuscular effects of venoms and crotoxin-like proteins from Crotalus durissus ruruima and Crotalus durissus cumanensis in mice phrenic-diaphragm preparation. It was concluded that both venoms present neurotoxic activity as a consequence of their crotoxin content. Furthermore, crotoxin from C.d. cumanensis is more potent than that from C.d. ruruima venom. At the concentration range in which both venoms express neurotoxic activity, only C.d. cumanensis venom also manifest a direct myotoxic effect that probably involves the synergic participation of other components than crotoxin. [ABSTRACT FROM AUTHOR]

[Display omitted] • Bovine lactoferrin leads gut microbiota dysbiosis. • Lactoferrin up or down-modulates expansion of fecal prominent microbiome lineages. • Bovine lactoferrin modulates fecal microbiome regardless stress condition. Lactoferrin, a diferric-binding glycoprotein drives the abundance of some gut microbiota members, but its role under stress conditions is unknown thus this aspect was the aim of this contribution. Female BALB/c mice (n = 4/group), treated orally with lactoferrin for 7 days were either stressed by board-immobilization from the 4th-to-7th day of treatment (LS) or unstressed (L). Two groups provided with water and stressed (S) or unstressed (C) were included. On day 7, feces were collected for the massive sequencing of V4-V5 region of the 16S rDNA gene. Regarding C -group, the only significant changes were found in the L -group that showed an increased abundance in most taxa of the genus Bacteroides (Phylum Bacteroidetes) and Parasuterella (Phylum Proteobacteria) or decreased of Clostridium _XIVb (Phylum Firmicutes), Lactoferrin-associated microbiota changes may result from stress independent modulatory pathways. Data may provide experimental foundations for using lactoferrin as a therapeutic co-adjuvant for diseases like obesity with microbiome alterations. [ABSTRACT FROM AUTHOR]

Abstract: This paper reports the biochemical and pharmacological characterization of a new myotoxic PLA2 (EC 3.1.1.4) called PhTX-I, purified from Porthidium hyoprora venom by one step analytical chromatography reverse phase HPLC. The homogeneity of the PhTX-I fraction and its molecular mass were initially evaluated by SDS–PAGE and confirmed by MALDI-TOF spectrometry, indicating a molecular mass of 14.249Da and constituted of a single polipeptidic chain. Amino acid sequence was determined by “de novo sequencing,” in tandem mass spectrometry, belonging to D49-PLA2 enzyme class and exhibiting high identity (44–90%) with other myotoxics PLA2 from snake venoms. The enzymatic investigation showed maximal activity at pH 8 and 35–45°C. This activity was dependent on Ca2+, other cations (Mg2+, Mn2+, Cd2+ and Zn2+) reduced notably the enzymatic activity, suggesting that the arrangement of the catalytic site presents an exclusive structure for Ca2+. Ex vivo, whole venom and PhTX-I PLA2 caused blockade of the neuromuscular transmission in young chick biventer cervicis preparations similar to other isolated snake venom toxins from the Bothrops genus. In vivo, both induced local myotoxicity and systemic interleukin-6 response upon intramuscular injection, additionally, induced moderate footpad edema. In vitro, both induced low cytotoxicity in skeletal muscle myoblasts, however PhTX-I PLA2 was able to lyse myotubes. [Copyright &y& Elsevier]

Abstract: Purpose: The purpose of the study was to describe the clinical characteristics and outcomes of critically ill patients with 2009 influenza A(H1N1). Methods: An observational study of patients with confirmed or probable 2009 influenza A(H1N1) and respiratory failure requiring mechanical ventilation was performed. Results: We studied 96 patients (mean age, 45 [14] years [mean, SD]; 44% female). Shock and acute respiratory distress syndrome were diagnosed during the first 72 hours of admission in 43% and 72% of patients, respectively. Noninvasive positive pressure ventilation was used in 45% of the patients, but failed in 77% of them. Bacterial pneumonia was diagnosed in 33% of cases, 8% during the first week (due to community-acquired microorganisms) and 25% after the first week (due to gram-negative bacilli and resistant gram-positive cocci). Intensive care unit mortality was 50%. Nonsurvivors differed from survivors in the prevalence of cardiovascular, respiratory, and hematologic failure on admission and late pneumonia. Reported causes of death were refractory hypoxia, multiorgan failure, and shock (50%, 38%, and 12% of all causes of death, respectively). Conclusions: Patients with 2009 influenza A(H1N1) and respiratory failure requiring mechanical ventilation often present with clinical criteria of acute respiratory distress syndrome and shock. Bacterial pneumonia is a frequent complication. Mortality is high and is primarily due to refractory hypoxia. [Copyright &y& Elsevier]

Abstract: Two major crotamine isoforms (III-4 and III-7) were obtained combining two chromatographic steps on molecular exclusion chromatography (Sephadex G-75) and ion-exchange column (Protein Pack SP 5PW) of the rattlesnake Crotalus durissus cumanensis venom. The “in vivo” myotoxic effect of the venom, its “in vitro” cytotoxicity in myoblasts and myotubes (C2C12) and the neurotoxic and edema-forming activity were characterized. The molecular masses of the crotamine isoforms were 4907.94 Da (III-4) and 4985.02 Da (III-7) and, as determined by mass spectrometry, both contained six Cys residues. Enzymatic hydrolysis followed by de novo sequencing through tandem mass spectrometry was used to determine the primary structure of both isoforms. III-4 and III-7 isoforms presented a 42-amino acid residues sequence and showed high molecular amino acid sequence identity with other crotamine-like proteins from Crotalus durissus terrificus. In vivo, both crotamine isoforms induced myotoxicty and a systemic interleukin-6 response upon intramuscular injection. These new crotamine isoforms induced low cytotoxicity in skeletal muscle myoblasts and myotubes (C2C12) and both induced a facilitatory effect on neuromuscular transmission in young chick biventer cervicis preparation. Edema-forming activity was also analyzed by injection of the crotamine isoforms into the right paw, since both crotamine isoforms exert a strong pro-inflammatory effect. [Copyright &y& Elsevier]

Abstract: The thrombin-like serine protease TLBm from Bothrops marajoensis was isolated in one chromatographic step in reverse phase HPLC. Its molecular mass was 33239.95Da, as based on the determined primary structure and confirmed experimentally by MALDI-TOF mass spectrometry (33332.5Da) and it contains 12 half-cysteine residues. This TLBm exhibited high specificity for BAρNA, Michaelis–Menten behavior with K m 2.3×10−1 M and the V max 0.52×10−1 nmoles ρ-NA/lt/min for this substrate. TLBm also showed ability to coagulate bovine fibrinogen and was inhibited by soybean trypsin inhibitor, EDTA and S(Dm) from the serum of the species Didelphis marsupialis. The primary structure of TLBm showed the presence of His(45), Asp(103) and Ser(228) residues in the corresponding positions of the catalytic triad established in the serine proteases and Ser(228) are inhibited by phenylmethylsulfonyl fluoride (PMSF). Amino acid analysis showed a high content of Asp, Glu, Gly, Ser, Ala and Pro as well as 12 half-cysteine residues and calculated pI of 6.47; TLBm presented 285 amino acid residues. In this work, we investigated the ability of TLBm to degrade fibrinogen and we observed that it is able to cause α- and β-chain cleavage. Enzymatic as well as the platelet aggregation activities were strongly inhibited when incubated with PMSF, a specific inhibitor of serine protease. Also, TLBm induced platelet aggregation in washed and platelet-rich plasma, and in both cases, PMSF inhibited its activity. [Copyright &y& Elsevier]

Abstract: This work reports the purification, biological characterization and amino acid sequence of two new basic PLA2 isoforms, Cdc-9 and Cdc-10, purified from the Crotalus durissus cumanensis venom by one step analytical chromatography reverse phase HPLC. The molecular masses of the PLA2 were 14,175±2.7 Da for Cdc-9 and 14,228±3.5 Da for Cdc-10 both deduced by primary structure and confirmed by MALDI-TOF. The isoforms presented an amino acid sequence of 122 amino acid residues, being Cdc-9: SLVQFNKMIK FETRKSGLPF YAAYGCYCGW GGQRPKDATD RCCFVHDCCY GKVAKCNTKW DIYSYSLKSG YITCGKGTWC KEQICECDRV AAECLRRSLS TYKNEYMFYP DSRCREPPEY TC with pI value of 8.25 and Cdc-10: SLLQFNKMIK FETRKSGVPF YAAYGCYCGW GGRRPKDPTD RCCFVHDCCY GKLTKCNTKW DIYSYSLKSG YITCGKGTWC KEQICECDRV AAECLRRSLN TYKNEYMFYP DSRCRGPPEY TC with a pI value of 8.46, showing highly conserved Ca2+-binding and catalytic sites. The PLA2 activity decreased when the isoforms Cdc-9 and Cdc-10 were incubated with 4-bromophenacyl bromide (p-BPB), anhydrous acetic acid and p-nitrobenzene sulfonyl fluoride (NBSF) when compared with the activity of both native isoforms. In mice, the PLA2 isoforms Cdc-9 and Cdc-10 induced myonecrosis and edema. Myotoxic and edema activities were reduced after treatment of the isoforms with p-BPB; acetylation of the lysine residues and the treatment of PLA2 with NBSF have also induced edema reduction. However, p-BPB strongly diminishes the local and systemic myotoxic effects. [Copyright &y& Elsevier]

Abstract: We report the purification and biochemical/pharmacological characterization of two myotoxic PLA2 (BbTX-II K49 PLA2 homologue and BbTX-III PLA2) from Bothrops brazili venom. Both were purified by a single chromatographic step on reverse phase HPLC, showing M r ∼14kDa for both myotoxins, showing high content of hydrophobic and basic amino acids as well as 14 half-cysteine residues. The BbTX-II K49 PLA2 homologue and BbTX-III PLA2, had a sequence of 121 amino acid residues. BbTX-II: SLFELGKMILQETGKNPAKSYGAYGCYCGVLGRGKPKDATDRCCYVHKCCYKLTGCDNKKKDRYSYSWKDKTIVCGENNPCLKELCECDKAVAICLRENLNTYNKKYRYHLKPLCKKADAC with pI value 8.73. BbTX-III: SLWEWGQMILKETGKNPFPYYGAYGCYCGWGGRRKPKDATDRCCFVHDCCRYKKLTGCPKTNDRYSYSRLDYTIVCGEDDPCKEICECDKAAAVCFRENLRTYNKKYMAHLRVLCKKDKPC with a pI value of 8.46. BbTX-III presented PLA2 activity in the presence of a synthetic substrate and showed a minimum sigmoidal behavior, reaching its maximal activity at pH 8.0 and 35–45°C. Maximum PLA2 activity required Ca2+. In vitro, BbTX-II K49 PLA2 homologue and BbTX-III PLA2 caused a blockade of the neuromuscular transmission in young chick biventer cervicis preparations in a similar way to other Bothrops species. In mice, BbTX-II K49 PLA2 homologue and BbTX-III PLA2 induces myonecrosis and edema-forming activity. All these biological effects induced by the BbTX-II K49 PLA2 homologue, occur in the absence of a measurable PLA2 activity in vitro, further supporting the concept of catalytic independent mechanisms exerted by Lys49 proteins. [Copyright &y& Elsevier]

Abstract: Potential food sources and the trophic position of some of the most conspicuous faunal components (vent and non-vent) were examined in the deep-hydrothermal vent system of Guaymas Basin, in the Gulf of California using carbon and nitrogen stable isotope analyses. The isotopic signatures of 13 species collected by the DSRV Alvin and Nautile mostly from sulfide-influenced habitats were analyzed. The δ13C of nine vent species had a wide range (−36.0‰ to −12.7‰), whereas the δ15N values varied from −5.0‰ to+9.4‰. The dual isotopic approach allowed the recognition of two main groups containing vent-endemic fauna. One was represented by an assemblage of eight species associated with sulfide deposits, visually dominated by the siboglinid worm Riftia pachyptila and characterized by enriched δ13C values (means −13.7‰ to −21.0‰). The second group included a single species, the bivalve Vesicomya gigas, an inhabitant of soft sediments, which had depleted δ13C and δ15N signatures (means −35.7‰ and −1.5‰). The galatheid Munidopsis alvisca is an exception among the species in the R. pachyptila aggregation, due to its depleted δ13C (−26.4‰) and an intermediate δ15N value (+5.5‰). Isotopic δ13C and δ15N signatures of four non-vent species exhibited mostly enriched δ15N values (means δ13C −27.8‰ to −13.6‰; δ15N +14.5‰ to +17.9‰), expected for higher consumers and detritivores in a deep-sea food web. They may benefit from the vent production via microbial matter or decaying vent organisms. Vent and non-vent fauna were assigned to five feeding guilds: symbiont-containing fauna, bacterivores, detritivores, predator–scavengers, and suspension-feeders. Based on isotopic values of vent and non-vent fauna, as well as that of surficial sediments, it is inferred that the hydrothermal ecosystem in the Guaymas Basin is self-supported with high-energy efficiency and with low exporting capacity to the background deep-sea food web. [Copyright &y& Elsevier]

The two-domain multicopper oxidases are proposed to be key intermediates in the evolution of three-domain multicopper oxidases. A number of two-domain multicopper oxidases have been identified from genome sequences and are classified as type A, type B, or type Con the basis of the predicted location of the type 1 copper center. The crystal structure of blue copper oxidase, a type C two-domain multicopper oxidase from Nitrosomonas europaea, has been determined to 1.9 Å resolution. Blue copper oxidase is a trimer, of which each subunit comprises two cupredoxin domains. Each subunit houses a type 1 copper site in domain 1 and a type 2/type 3 trinuclear copper cluster at the subunit-subunit interface. The coordination geometry at the trinuclear copper site is consistent with reduction of the copper ions. Although the overall architecture of blue copper oxidase is similar to nitrite reductases, detailed structural alignments show that the fold and domain orientation more closely resemble the three-domain multicopper oxidases. These observations have important implications for the evolution of nitrite reductases and multicopper oxidases. [ABSTRACT FROM AUTHOR]

Abstract: The patterns of myotoxicity induced in mice by crotoxin, crotoxin B and a Lys49 phospholipase A2 (PLA2) homologue were compared. Lys49 PLA2-induced local myotoxicity is reflected by creatine kinase (CK) loss in injected gastrocnemius muscle, and by a profile of CK increase in plasma characterized by a rapid increment and drop after intramuscular injection, and by a lack of CK increase in plasma after intravenous injection. In contrast, crotoxin and crotoxin B, which induce local and systemic myotoxicity, provoked a more prolonged increment in plasma CK activity upon intramuscular injection, and induced increments in plasma CK after intravenous injection. The three toxins promoted a similar extent of local myotoxicity, assessed by the loss of CK in injected gastrocnemius. A method for the quantitative assessment of the ability of toxins to induce systemic myotoxicity is proposed, based on the estimation of the ratio between the area under the curve in the plasma CK activity (total myotoxicity) to the loss of CK in injected gastrocnemius (local myotoxicity). The highest ratio corresponded to crotoxin, and the lowest corresponded to Lys49 PLA2, the former being a systemic myotoxin and the latter a local myotoxin. Neutralization by antivenoms also differed between the toxins: a drastic reduction in plasma CK, with very poor neutralization of local CK loss, was achieved in the case of crotoxin B when antivenom was injected intravenously, whereas no neutralization was achieved in the case of Lys49 PLA2. When tested in undifferentiated myoblasts in culture, Lys49 PLA2 induced cytotoxicity, whereas crotoxin and crotoxin B did not, evidencing that the latter are devoid of widespread cytolytic activity. Molecular modeling analysis showed that Lys49 PLA2 has a conspicuous cationic face, which is likely to interact with diverse membranes. In contrast, crotoxin B, despite its overall basic pI, has a lower density of positively charged residues at this molecular region. It is suggested that Lys49 PLA2s homologues interact, through this cationic face, with many different cell types, thus lacking specificity for muscle cells. In contrast, crotoxin B has a more selective interaction with targets in the muscle cell membrane. This selectivity might be the basis for the ability of crotoxin and crotoxin B to induce systemic myotoxicity. [Copyright &y& Elsevier]

Abstract: BaTX PLA2, a K49 phospholipase A2 homologue was purified from Bothrops alternatus venom after two chromatographic steps, molecular exclusion on Superdex 75 and reverse phase HPLC on μ-Bondapack C-18. A molecular mass of 13898.71 Da was determined by MALDI-TOF mass spectrometry. The amino acid composition showed that BaTX has a high content of Lys, Tyr, Gly, Pro, and 14 half-Cys residues, typical of a basic PLA2. The complete amino acid sequence of BaTX PLA2 contains 121 residues, resulting in a calculated pI value of 8.63. This sequence shows high identity values when compared to other K49 PLA2s isolated from the venoms of viperid snakes. Lower identity is observed in comparison to D49 PLA2s. The sequence was SLFELGKMIL QETGKNPAKS YGAYYCYCGW GGQGQPKDAT DRCCYVHKCC YKKLTGCNPK KDRYSYSWKD KTIVCGENNS CLKELCECDK AVAICLRENL NTYNKKYRYY LKPLCKKADA C. In mice, BaTX induced myonecrosis and edema, upon intramuscular or subcutaneous injections, respectively. The LD50 of BaTX was 7 μg/g body weight, by intravenous route. In vitro, the toxin caused a potent blockade of neuromuscular transmission in young chicken biventer cervicis preparations. The blockage 50% was achieved at a concentration of 0.03 μM: 40±0.4 min and 0.07 μM: 35±0.3 min. Moreover, this protein induced a rapid cytolytic effect upon mouse skeletal muscle myoblasts in culture. Thus, the combined structural and functional information obtained identify BaTX as a new member of the K49 PLA2 family, which presents the typical bioactivities described for such proteins. [Copyright &y& Elsevier]

The Alarcón Rise (AR) hydrothermal system recently discovered in the Southern Gulf of California is characterized by the presence of black smokers, fluids with temperatures up to 360 °C, high concentrations of metal-sulfides and H 2 S. The trophic structure and the energy flow in the vent community were determined through the carbon (δ13C), nitrogen (δ15N), and sulfur (δ34S) isotopic signatures of 19 macrofaunal species. The δ13C values had an ample range from −36 and −8‰, reflecting a wide variety of carbon sources and the predominance of organic carbon fixed through the reductive tricarboxylic acid cycle (rTCA). The δ15N values varied from −7.9 and 18‰, corresponding to primary and secondary consumers, and the most enriched value (18‰) to a non-vent organism. Dominant organisms included primary consumers such as symbiont-bearing, and bacterivores, which revealed the importance of the bacterial consortium in the energy transfer. Secondary consumers comprised scavengers/detritivores, the most diverse guild, and predators, rather scarce. The δ34S values were between −14.5 and 15.6‰, indicating the assimilation of magmatic sulfur in the vent-fauna, and the complementary assimilation of photosynthetically derived organic matter in the non-vent organisms, hinted by their highest value (15.6‰). Interestingly, an unidentified Actiniaria anemone displayed anomalously depleted δ13C values (−30.4‰), reflecting a potential symbiotic relationship with sulfur-oxidizing endobacteria. The trophic structure of the vent fauna of Alarcón Rise included five trophic guilds. Among the primary consumers, the symbiont-bearing species were dominant in biomass. The scavengers/detritivores were the most diverse guild, while predators were scarce. The dominating carbon fixation pathway was the reverse tricarboxylic acid cycle. The high δ34S value of 15.6 ‰ indicated photosynthetic inputs to the non-vent fauna. [ABSTRACT FROM AUTHOR]

The Central Costa Rica Deformed Belt (CCRDB) is a diffuse faulting area that represents the western border of the Panama Microplate. Using the Markov Chain – Monte Carlo method and under three scenarios of the spatial distribution of the CCRDB, we analyzed the inter-seismic crustal deformation in Costa Rica and its surroundings based on the results of the Global Navigation Satellite System (GNSS) observations for Costa Rica, Nicaragua, and Panama. We assumed that the observed inter-seismic crustal deformation on the surface is a result of the kinematic effects of the rigid tectonic blocks motion, the elastic deformation due to the block interface interactions and the internal strain inside of the tectonic blocks. Assuming that the seismic moment in the subduction and inland interfaces is accumulated only as an elastic strain and is then released co-seismically, the resulting seismic moment accumulated rates reflect the capacity for producing earthquakes M w > 8 along the Cocos Plate convergence and earthquakes M w > 7 along the inland interfaces. Although these are the values that the modeling outputs, limited historical data suggests that this earthquake potential might be overestimated, but the historical seismicity in Costa Rica is still short for disesteeming higher earthquake potential levels. • Seismic moment accumulated rates in subduction show capacity for M w > 8 earthquakes. • Seismic moment accumulated rates in inland show capacity for M w > 7 earthquakes. • Historical seismicity in Costa Rica is still short for disesteeming high EQ potential. [ABSTRACT FROM AUTHOR]

Bacteria play an important role in ecological processes in oil contaminated marine sediments. In this work, bacterial diversity studies with surface sediment samples from the NW Gulf of Mexico were performed, two from continental shelf and two from upper slope. The bacterial communities seem significantly influenced by depth, distance from the shoreline, temperature, dissolved oxygen and aluminum. The most abundant Phylum was Proteobacteria , Class Gammaproteobacteria. However, Class Deltaproteobacteria , Order Desulfuromonadales predominated in continental shelf and Order Alteromonadales (Gammaproteobacteria) prevailed in the upper slope sediments. Many potential hydrocarbon degrading bacterial genera were identified, 71 of the assigned genera were associated to hydrocarbon degradation processes. The genera Desulfobulbus and Haliea were confined to continental inner-shelf, while Shewanella and Fusibacter were mostly detected in deeper sediments. The occurrence and abundance of putative hydrocarbon degrading bacteria in this area, could be indicative of an impacted zone caused by the presence hydrocarbons in the environment. Image 1 • In this study, we describe the bacterial diversity present in surface sediments from the North West region of the Gulf of Mexico, a poorly studied zone. • The bacterial communities seem significantly influenced by depth, distance from the shoreline, temperature and dissolved oxygen. • The occurrence and abundance of putative hydrocarbon degrading bacteria in this area, could be indicative of an impacted zone. [ABSTRACT FROM AUTHOR]

We conducted a multi-institutional dosimetric audit between FLASH and conventional dose rate (CONV) electron irradiations by using an anatomically realistic 3-dimensional (3D) printed mouse phantom. A computed tomography (CT) scan of a live mouse was used to create a 3D model of bony anatomy, lungs, and soft tissue. A dual-nozzle 3D printer was used to print the mouse phantom using acrylonitrile butadiene styrene (∼1.02 g/cm3) and polylactic acid (∼1.24 g/cm3) simultaneously to simulate soft tissue and bone densities, respectively. The lungs were printed separately using lightweight polylactic acid (∼0.64 g/cm3). Hounsfield units (HU), densities, and print-to-print stability of the phantoms were assessed. Three institutions were each provided a phantom and each institution performed 2 replicates of irradiations at selected anatomic regions. The average dose difference between FLASH and CONV dose distributions and deviation from the prescribed dose were measured with radiochromic film. Compared with the reference CT scan, CT scans of the phantom demonstrated mass density differences of 0.10 g/cm3 for bone, 0.12 g/cm3 for lung, and 0.03 g/cm3 for soft tissue regions. Differences in HU between phantoms were <10 HU for soft tissue and bone, with lung showing the most variation (54 HU), but with minimal effect on dose distribution (<0.5%). Mean differences between FLASH and CONV decreased from the first to the second replicate (4.3%-1.2%), and differences from the prescribed dose decreased for both CONV (3.6%-2.5%) and FLASH (6.4%-2.7%). Total dose accuracy suggests consistent pulse dose and pulse number, although these were not specifically assessed. Positioning variability was observed, likely due to the absence of robust positioning aids or image guidance. This study marks the first dosimetric audit for FLASH using a nonhomogeneous phantom, challenging conventional calibration practices reliant on homogeneous phantoms. The comparison protocol offers a framework for credentialing multi-institutional studies in FLASH preclinical research to enhance reproducibility of biologic findings. [ABSTRACT FROM AUTHOR]

Ultrahigh-dose-rate (FLASH) irradiation has been reported to reduce normal tissue damage compared with conventional dose rate (CONV) irradiation without compromising tumor control. This proof-of-concept study aims to develop a deep learning (DL) approach to quantify the FLASH isoeffective dose (dose of CONV that would be required to produce the same effect as the given physical FLASH dose) with postirradiation mouse intestinal histology images. Eighty-four healthy C57BL/6J female mice underwent 16 MeV electron CONV (0.12 Gy/s; n = 41) or FLASH (200 Gy/s; n = 43) single fraction whole abdominal irradiation. Physical dose ranged from 12 to 16 Gy for FLASH and 11 to 15 Gy for CONV in 1 Gy increments. Four days after irradiation, 9 jejunum cross-sections from each mouse were hematoxylin and eosin stained and digitized for histological analysis. CONV data set was randomly split into training (n = 33) and testing (n = 8) data sets. ResNet101-based DL models were retrained using the CONV training data set to estimate the dose based on histological features. The classical manual crypt counting (CC) approach was implemented for model comparison. Cross-section-wise mean squared error was computed to evaluate the dose estimation accuracy of both approaches. The validated DL model was applied to the FLASH data set to map the physical FLASH dose into the isoeffective dose. The DL model achieved a cross-section-wise mean squared error of 0.20 Gy2 on the CONV testing data set compared with 0.40 Gy2 of the CC approach. Isoeffective doses estimated by the DL model for FLASH doses of 12, 13, 14, 15, and 16 Gy were 12.19 ± 0.46, 12.54 ± 0.37, 12.69 ± 0.26, 12.84 ± 0.26, and 13.03 ± 0.28 Gy, respectively. Our proposed DL model achieved accurate CONV dose estimation. The DL model results indicate that in the physical dose range of 13 to 16 Gy, the biologic dose response of small intestinal tissue to FLASH irradiation is represented by a lower isoeffective dose compared with the physical dose. Our DL approach can be a tool for studying isoeffective doses of other radiation dose modifying interventions. [ABSTRACT FROM AUTHOR]

• Oxygen depletion during irradiation was measured dynamically using a nanoparticle. • Oxygen depletion yields was measured at 200 Hz using a fiber-optic system. • Ultra-high dose rate radiation depleted 13% less oxygen than conventional radiation. • Radiochemical oxygen depletion is lower under hypoxic conditions, i.e., below 20 µM. The rapid depletion of oxygen during irradiation at ultra-high dose rate calls for tissue oximeters capable of high temporal resolution. This study demonstrates a water-soluble phosphorescent nanoprobe and fiber-coupled instrument, which together are used to measure the kinetics of oxygen depletion at 200 Hz during irradiation of in vitro solutions. [ABSTRACT FROM AUTHOR]

Nitrifier denitrification is the conversion of nitrite to nitrous oxide by ammonia-oxidizing organisms. This process, which is distinct from denitrification, is active under aerobic conditions in the model nitrifier Nitrosomonas europaea. The central enzyme of the nitrifier dentrification pathway is a copper nitrite reductase (CuNIR). To understand howa CuNIR, typically inactivated by oxygen, functions in this pathway, the enzyme isolated directly fromN. europaea (NeNIR) was biochemically and structurally characterized. NeNIR reduces nitrite at a similar rate to other CuNIRs but appears to be oxygen tolerant. Crystal structures of oxidized and reduced NeNIR reveal a substrate channel to the active site that is much more restricted than channels in typical CuNIRs. In addition, there is a second fully hydrated channel leading to the active site that likely acts awater exit pathway. The structure is minimally affected by changes in pH. Taken together, these findings provide insight into the molecular basis for NeNIR oxygen tolerance. [ABSTRACT FROM AUTHOR]

Abstract: We suggest a geometrical framework to discuss the action of slabs of negatively refracting materials. We show that these slabs generate the same orbits as normal materials, but traced out in opposite directions. This property allows us to confirm that the action of any lossless multilayer can be optically canceled by putting it together with the multilayer constructed as the inverted mirror image, with ε and μ reversed in sign. [Copyright &y& Elsevier]