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Abstract Patella candei d'Orbigny, 1840 is a valuable resource from the European Macaronesia. Limpet aquaculture is a recent research field that could contribute to reducing anthropogenic impact and developing appropriate restocking technologies. This study presents the results of 14 assays performed under laboratory culture conditions aimed at: (1) improving the larval production methodologies for limpets through the optimization of the artificial maturation of the oocytes and the sperm density required for fertilization and incubation, (2) validating a larviculture protocol for P. candei, and (3) evaluating rearing density effect on larvae performance until the pediveliger stage. Results obtained in the present study indicate that NH4OH is more efficient than KOH and NaOH to enhance the artificial maturation of the oocytes. The optimal combination was NH4OH at pH 9.0 for a duration of 20–30 min. The optimal sperm density was approximately 105 sperm cells mL−1 as in other limpet species. The larviculture method described hereby demonstrated to be efficient to obtain viable pediveligers, that is, the larval survival was high, and the artificial maturation did not influence negatively the posterior larval development. The rearing density, within a range from 2.5 to 30 larvae mL−1, showed minimal influence on survival and development.

Patella candei d'Orbigny, 1840 is a valuable resource from the European Macaronesia. Limpet aquaculture is a recent research field that could contribute to reducing anthropogenic impact and developing appropriate restocking technologies. This study presents the results of 14 assays performed under laboratory culture conditions aimed at: (1) improving the larval production methodologies for limpets through the optimization of the artificial maturation of the oocytes and the sperm density required for fertilization and incubation, (2) validating a larviculture protocol for P. candei, and (3) evaluating rearing density effect on larvae performance until the pediveliger stage. Results obtained in the present study indicate that NH4OH is more efficient than KOH and NaOH to enhance the artificial maturation of the oocytes. The optimal combination was NH4OH at pH 9.0 for a duration of 20–30 min. The optimal sperm density was approximately 105 sperm cells mL−1 as in other limpet species. The larviculture method described hereby demonstrated to be efficient to obtain viable pediveligers, that is, the larval survival was high, and the artificial maturation did not influence negatively the posterior larval development. The rearing density, within a range from 2.5 to 30 larvae mL−1, showed minimal influence on survival and development. [ABSTRACT FROM AUTHOR]

Comparisons between the preservation potential of Mars-analog environments have historically been qualitative rather than quantitative. Recently, however, laboratory-based artificial maturation combined with kinetic modeling techniques have emerged as a potential means by which the preservation potential of solvent-soluble organic matter can be quantified in various Mars-analog environments. These methods consider how elevated temperatures, pressures, and organic–inorganic interactions influence the degradation of organic biomarkers post-burial. We used these techniques to investigate the preservation potential of deposits from a circumneutral iron-rich groundwater system. These deposits are composed of ferrihydrite (Fe5HO8 · 4H2O), an amorphous iron hydroxide mineral that is a common constituent of rocks found in ancient lacustrine environments on Mars, such as those observed in Gale Crater. Both natural and synthetic ferrihydrite samples were subjected to hydrous pyrolysis to observe the effects of long-term burial on the mineralogy and organic content of the samples. Our experiments revealed that organic–inorganic interactions in the samples are dominated by the transformation of iron minerals. As amorphous ferrihydrite transforms into more crystalline species, the decrease in surface area results in the desorption of organic matter, potentially rendering them more susceptible to degradation. We also find that circumneutral iron-rich deposits provide unfavorable conditions for the preservation of solvent-soluble organic matter. Quantitative comparisons between preservation potentials as calculated when using kinetic parameters show that circumneutral iron-rich deposits are ∼25 times less likely to preserve solvent-soluble organic matter compared with acidic, iron-rich environments. Our results suggest that circumneutral iron-rich deposits should be deprioritized in favor of acidic iron- and sulfur-rich deposits when searching for evidence of life with solvent extraction techniques. [ABSTRACT FROM AUTHOR]

Although artificial maturation of hydrocarbon source rocks by laboratory pyrolysis is far from representing natural maturation, it is a useful tool to investigate the process. In this study, we used routine open system pyrolysis for powder samples and Restricted System anhydrous Pyrolysis (RSP) for cm-sized Silurian shale source rock fragments to artificially mature the samples to different end-temperatures in the presence of a flowing carrier gas. Maturation experiments on rock fragments enable the simulation of physical barriers for the generated hydrocarbons that need to be overcome before expulsion from the source rock can occur. Based on the artificial maturation results in this study, oil expulsion efficiency from the Silurian shale source rock was 46% at the early oil generation stage and increased to 74% at approximately the peak oil generation stage. Furthermore, we have compared artificial maturation results from powder-form and fragment-form samples with natural-maturation series and found that artificial maturation of fragment-form samples sufficiently resembles natural maturation of the Silurian shales. It is therefore possible to simulate the early, middle and peak oil generation stages of natural maturation and expulsion efficiencies. This implies that, lab-based oil expulsion efficiencies from increasing maturity and hydrocarbon generation can be incorporated into the basin modeling. Basic analytical protocols for open-system and restricted-system pyrolysis employed to determine oil expulsion efficiency. [Display omitted] • Powder- and fragment-form Silurian shale samples were artificially matured. • Artificial maturation of fragment-form samples is more comparable to natural maturation. • Oil expulsion efficiency can be estimated at varying artificial maturation stages. • Artificial maturation-based oil expulsion efficiency estimates can be used to calibrate basin models. [ABSTRACT FROM AUTHOR]

This paper addresses challenges in characterizing unconventional shale reservoirs. For the first time, the nuclear magnetic resonance (NMR) and dielectric responses are integrated to characterize intact, saturated, and kerogen-rich subsurface shale samples at various maturation stages. The NMR and dielectric were measured separately using independent pieces of equipment, and all NMR and dielectric measurements were carried out at surface conditions. A comprehensive assessment is provided to address the changes induced by maturation through combined geochemical and petrophysical analyses. Shale samples from the Upper Cretaceous sequence of Jordan were characterized using Rock-Eval analysis, before and after maturation treatments. The total organic carbon (TOC) was decreased from 17.4 to 13.8 and 11.3 wt% and the pyrolyzed sulfur content was decreased from 3.32 to 0.25 and 0.15 3.18%, after maturing the samples at 250 °C for 1 and 5 days, respectively. The study employed NMR to track changes in pore structure via T 2 relaxation time and measured dielectric properties and conductivity dispersion across frequencies from 10 MHz to 1 GHz using a wideband open-ended coaxial probe. After the maturation treatments, the dielectric constant of saturated shale samples doubled, and the conductivity increased by over three times. These changes in dielectric properties can be attributed to increased fluid-rock interfacial polarization and the formation of new pore spaces during maturation. NMR findings also indicated the emergence of a new pore system within the organic matter and the development of new fractures, resulting in a 6 to 12% increase in total porosity. The results obtained indicate that maturation-induced microstructural changes have a more significant influence on the dielectric responses than alterations on total organic carbon. • Dielectric and NMR are used for the first time on intact, saturated, and kerogen-rich subsurface shale samples at various maturation stages. • The use of rock samples instead of crushed powder provides a better representation of the shale complex microstructure. • The kerogen distribution plays a significant role; scattered organic matter causes greater TOC reduction than accumulated. • · The changes in dielectric properties induced by maturation are more significant than those reported in the literature. • The changes in dielectric response upon maturation are primarily due to changes in geometry and pore connectivity. [ABSTRACT FROM AUTHOR]

Acidic iron- and sulfur-rich streams are appropriate analogues for the late Noachian and early Hesperian periods of martian history, when Mars exhibited extensive habitable environments. Any past life on Mars may have left behind diagnostic evidence of life that could be detected at the present day. For effective preservation, these remains must have avoided the harsh radiation flux at the martian surface, survived geological storage for billions of years, and remained detectable within their geochemical environment by analytical instrument suites used on Mars today, such as thermal extraction techniques. We investigated the detectability of organic matter within sulfur stream sediments that had been subjected to artificial maturation by hydrous pyrolysis. After maturation, the samples were analyzed by pyrolysis–gas chromatography–mass spectrometry (py-GC-MS) to determine whether organic matter could be detected with this commonly used technique. We find that macromolecular organic matter can survive the artificial maturation process in the presence of iron- and sulfur-rich minerals but cannot be unambiguously distinguished from abiotic organic matter. However, if jarosite and goethite are present in the sulfur stream environment, they interfere with the py-GC-MS detection of organic compounds in these samples. Clay reduces the obfuscating effect of the oxidizing minerals by providing nondeleterious adsorption sites. We also find that after a simple alkali and acid leaching process that removes oxidizing minerals such as iron sulfates, oxides, and oxyhydroxides, the sulfur stream samples exhibit much greater organic responses during py-GC-MS in terms of both abundance and diversity of organic compounds, such as the detection of hopanes in all leached samples. Our results suggest that insoluble organic matter can be preserved over billions of years of geological storage while still retaining diagnostic organic information, but sample selection strategies must either avoid jarosite- and goethite-rich outcrops or conduct preparative chemistry steps to remove these oxidants prior to analysis by thermal extraction techniques. [ABSTRACT FROM AUTHOR]

Different responsive abilities of different types of eels (cultured, cultured feminized, and wild silver eels) during artificial maturation are recognized, and maturity status at the beginning of artificial maturation might be important. Maturity may represented by the distribution pattern of oocyte diameters. Androgens have been demonstrated to stimulate ovarian development in eels. To determine the initial status, operations were performed on eels to identify sex and to sample ovarian tissue. The recovered eels were then treated with 17α-methyltestosterone (17MT), and the responses of individual eels to 17MT were determined by the fold change in the mean oocyte diameter before and after treatment. Sampled ovarian tissues were fixed in Bouin's solution, oocytes were isolated, and the diameter of isolated oocytes was measured. The ovarian status, determined by kernel density estimation (KDE), was presented by the probability density of measured oocyte diameters; compared with histograms, a description method, KDE, provided more subtle information on the investigated ovary. Our data indicated a correlation between the initial ovarian status (density pattern) and the consequence of treatment (change of ovary); we also argued the semelparity of the Japanese eel. Our results supported the hypothesis that the initial ovarian status is an important factor affecting artificial maturation and that androgens could ameliorate the initial status of the eel ovary. [ABSTRACT FROM AUTHOR]

Samples that are likely to contain evidence of past life on Mars must have been deposited when and where environments exhibited habitable conditions. Mars analog sites provide the opportunity to study how life could have exploited such habitable conditions. Acidic iron- and sulfur-rich streams are good geochemical analogues for the late Noachian and early Hesperian, periods of martian history where habitable conditions were widespread. Past life on Mars would have left behind fossilized microbial organic remains. These are often-sought diagnostic evidence, but they must be shielded from the harsh radiation flux at the martian surface and its deleterious effect on organic matter. One mechanism that promotes such preservation is burial, which raises questions about how organic biomarkers are influenced by the postburial effects of diagenesis. We investigated the kinetics of organic degradation in the subsurface of Mars. Natural mixtures of acidic iron- and sulfur-rich stream sediments and their associated microbial populations and remains were subjected to hydrous pyrolysis, which simulated the increased temperatures and pressures of burial alongside any promoted organic/mineral interactions. Calculations were made to extrapolate the observed changes over martian history. Our experiments indicate that low carbon contents, high water-to-rock ratios, and the presence of iron-rich minerals combine to provide unfavorable conditions for the preservation of soluble organic matter over the billions of years necessary to produce present-day organic records of late Noachian and early Hesperian life on Mars. Successful sample selection strategies must therefore consider the pre-, syn-, and postburial histories of sedimentary records on Mars and the balance between the production of biomass and the long-term preservation of organic biomarkers over geological time. [ABSTRACT FROM AUTHOR]

Abstract Investigating hydrocarbon generation and expulsion by pyrolysis is limited by methodologies incapable of simulating conditions close to those prevailing in natural systems. Destructive sample preparation, inappropriate pressure regimes and pyrolysis in closed mode and/or in the absence of water caused results not representative for natural processes. We here present a new approach for a laboratory scaled simulation of generation, primary migration and expulsion under near-natural conditions, using the "Expulsinator" device. Near-natural conditions are realized by application of lithostatic pressure onto a source-rock disc with intact pore network and by pyrolysis at the presence of water, conducted in open flow through mode. This study will give a detailed technical description of the apparatus and the methodology to implement an Expulsinator experiment. An Expulsinator experiment generates a combined generation and expulsion profile, resulting in a detailed source rock characterization, incorporating yields for oil and gas, as well as rock deformation data on mm- and μm-scale. Thus, information is provided about timing and amplitude of generation and expulsion events. The apparatus uses a novel way of continuous sampling during the pyrolysis, enabling product removal from the reactor during the generation and expulsion process. Sampling in open flow-through mode is technically demanding and requires stimulation by a modifier for quantitative removal of the expelled products from the reactor. Test experiments demonstrate that the modifier has no impact onto the expulsion behavior of the source rock. Following the technical description, the generation and expulsion profile of one Expulsinator experiment is discussed. Beside information about timing of product generation and expulsion, the experiment shows the connection between rock expansion/compression and expulsion events. The efficiency of this new methodology is compared with conventional closed hydrous pyrolysis. The results exhibit the advantages of the apparatus: Liquid yields are increased, and hydrocarbon (HC) -gas generation reduced, due to a suppression of secondary reaction by the open setup. Furthermore, conventional pyrolysis achieved lower expulsion rates, due to the absence of lithostatic pressure. The Expulsinator shows high potential for further applications, in particular for implementation of lab-simulation data into numeric models. Highlights • The Expulsinator offers a new approach to simulate petroleum generation and expulsion. • The Expulsinator provides data about amount and timing of generation and expulsion. • Measurable rock expansion/compression was associated with expulsion events. • Expulsinator experiments reduce reactions between secondary generation products. • Application of adequate lithostatic pressure increased the expulsion rate. [ABSTRACT FROM AUTHOR]

Abstract Chitinozoan, graptolite and organic-rich immature Upper Ordovician mudstone was artificially matured using closed hydrous pyrolysis. The pyrolysis was performed at isothermal temperatures of 310-350 °C at 10 °C increments for 72 h. This temperature range simulates the subsurface thermogenic hydrocarbon generation window based on previous laboratory simulations. The objectives of this study are to (a) qualitatively and quantitatively assess the degree of physicochemical transformation of dispersed organic matter (DOM) and zooclasts in BRF petroleum source rock after artificial maturation; and (b) determine the relationship between graptolite, chitinozoan, vitrinite-like particle and bitumen reflectance (R o) with increasing pyrolysis temperature and the thermal maturity. Petrographic analysis shows that bituminite and amorphous kerogen were the first organic macerals to thermally decompose after the first pyrolysis temperature. This is followed by liptodetrinite, thin-walled alginite, acritarch, and telalginite as pyrolysis temperature increases. Concurrently, the fluorescence properties of the telalginite shifted from greenish yellow to reddish-orange after the last stage (350 °C) pyrolysis. In addition, significant amount of bright fluorescing labile hydrocarbons produced during pyrolysis were observed oozing from pore spaces and on the surface of the rock matrix. Pore-filling, orange to reddish-orange fluorescing solid bitumen were also found in pores spaces created by the thermal decomposition of DOM. The lack of morphological evidence for the thermal decomposition of chitinozoans and graptolites suggests that these zooclasts macerals may have limited or have no contribution to the overall hydrocarbon generation. Nonetheless, their respective reflectance (R o) increased (0.64% to 1.34% and 0.55% to 1.38%) as the pyrolysis temperature was increased. These R o values are significantly higher than the vitrinite-like particles (0.49% to 1.07%) and solid bitumen (0.30% to 1.09%). The measured RocK-Eval T max and solid bitumen vitrinite reflectance equivalent (VR o-eqv) are comparable to the average vitrinite-like particles. The relationship between rate of increase in chitinozoan and graptolite, and vitrinite-like particles R o , expressed by the equations: R o-vit-like = 0.77 R chi and R o-vit-like = 0.79 R grap , are comparable to those observed in geologically matured source rocks. Highlights • Immature potential petroleum source rock was successfully artificially matured using closed hydrous pyrolysis. • Bituminite, amorphous kerogen and liptodetrinite thermally decompose first followed by telalginite and G.prisca. • The zooclasts and vitrinite-like particles R o have linear relationship: R o-vit-like = 0.77 R chi and R o-vit-like = 0.79 R grap. • Chitinozoan and graptolites may have little or no contribution to hydrocarbon generation. [ABSTRACT FROM AUTHOR]

As an alternative to classic batch hydrous pyrolysis experiments, this proof-of-concept study presents a version of open-system hydrous pyrolysis (OSHP) in which the design of the apparatus allows for a small, continuous flow of only liquid-phase water to pass through the reactor during artificial maturation. This allows volatile, liquid, and soluble materials to migrate freely through and out of the system, whereas insoluble mineral matter and kerogen remain within the reactor. This apparatus differs from previous OSHP designs in the ability to maintain true open-system conditions, thus minimizing any cracking or back reaction of the products with the residual kerogen. Using the OSHP apparatus, immature Anna Shale (Pennsylvanian age, Illinois Basin) containing Type II marine kerogen was matured artificially at experimental temperatures ranging from 300 to 360 °C for up to 72 h. Petrographically, the immature Anna Shale is dominated by a micrinitic groundmass, and contains lesser amounts of vitrinite (both collotelinite and collodetrinite), inertodetrinite, bituminite, solid bitumen, and alginite. Under run conditions, mean random reflectance increased from 0.46 to 1.81% for vitrinite and from 0.66% to 1.50% for solid bitumen. Alginite fluorescence changed from a bright yellow to dull red-orange and decreased in intensity until all fluorescence was lost in shales pyrolyzed at temperatures ≥350 °C. Rock-Eval T max increased from 425° to 520 °C, TOC decreased (e.g., from 12.5% to ∼9% at a run temperature of 360 °C), S1 decreased from 0.71 to ∼ < 0.1 mg HC/g shale, S2 decreased from ∼40 to <1.0 mg HC/g shale, and HI decreased from ∼300 to <10 mg HC/g TOC. These changes are consistent with the maturation of the immature shale through the oil window and into the gas window. With increased maturity, the shale showed a loss in mass: shorter runs (≤ 24 h) typically lost <10%, whereas longer runs (72 h) lost 12–20%. These losses were likely due to the loss of moisture, liberation of hydrocarbons and other gases, and depletion in total sulfur from 2.03 to ∼0.1 wt% (much of which was pyritic sulfur); higher mass losses may have included retention of material in the reactor, tubing, or frits. Petrographic observations revealed that pyrite framboids, which were abundant in the immature shale, decreased in samples pyrolyzed at temperatures >330 °C and showed evidence of alteration to hematite. The OSHP design was intended to mimic normal burial maturation. However, based on the significant depletion in sulfur (i.e., pyrite), the current design and run parameters may more closely replicate conditions associated with hydrothermal alteration, possibly those associated with intrusion of organic-rich rocks. It is also possible that the OSHP approach could lead to a better understanding of organic-mineral interactions and mobility of elements, especially trace elements, during maturation. • OSHP is presented as an alternative to classic hydrous pyrolysis. • OSHP allows volatile, liquid, and soluble materials to migrate out of the system. • R r , SB r , and T max increase indicating maturation of kerogen into the gas window. • Applications also include clay diagenesis, trace metal, and hydrothermal studies. [ABSTRACT FROM AUTHOR]

Complete sexual maturation of European eels ( Anguilla anguilla ) in captivity can only be achieved via injections with gonadotropins. For female eels this procedure takes 4–6 months and the response ranges from “unresponsive” to final maturation and ovulation. Reproductive success could be significantly increased via early selection of responders based on predictive markers and minimally invasive sampling methods. To get a better understanding of the genetic background of ovarian maturation of the European eel we performed a pilot deep-sequencing transcriptome analysis of ovarian tissue derived from a yellow eel, a prepubertal silver eel and a post-spawning matured eel. Two key players in steroidogenesis were strongly correlated with advanced sexual maturation, namely P450c17 and liver receptor homolog-1, suggesting that blood plasma steroids might qualify as minimally invasive markers for early detection of responders. Since the predictive value of plasma sex steroid levels for final maturation of the European eel had not yet been carefully examined, we performed an extensive artificial maturation trial. Farmed silver eels were treated with pituitary extracts and sampled at multiple time intervals. Expression of steroidogenesis-related genes in ovarian tissue of responding and non-responding eels after four weekly injections with pituitary extract was compared using a custom-built microarray and RNAseq. Increased expression of 17β-hsd1 was strongly linked to sexual maturation. Blood plasma levels of sex steroids were measured using ELISAs. We show that a 2.5-fold increase in blood-plasma estradiol level after 4 weekly pituitary extract injections is a strong predictor of final sexual maturation of female European eel. [ABSTRACT FROM AUTHOR]

Estradiol-17β (E 2 ) and maturation-inducing hormone (MIH) are two steroid hormones produced in the teleost ovary that are required for vitellogenic growth and final oocyte maturation and ovulation. During this transition, the main steroid hormone produced in the ovary shifts from estrogens to progestogens. In the commercially important Japanese eel ( Anguilla japonica ), the MIH 17α,20β-dihydroxy-4-pregnen-3-one (DHP) is generated from its precursor by P450c17, which has both 17α-hydroxylase and C 17-20 lyase activities. In order to elucidate the regulatory mechanism underlying the steroidogenic shift from E 2 to DHP and the mechanistic basis for the failure of this shift in artificially matured eels, the cDNA for cyp17a2 —which encodes P450c17-II—was isolated from the ovary of wild, mature Japanese eel and characterized, and the expression patterns of cyp17a1 and cyp17a2 during induced ovarian development were investigated in cultured eel ovaries. Five cDNAs (types I–V) encoding P450c17-II were identified that had minor sequence variations. HEK293T cells transfected with all but type II P450c17-II converted exogenous progesterone to 17α-hydroxyprogesterone (17α-P), providing evidence for 17α-hydroxylase activity; however, a failure to convert 17α-P to androstenedione indicated that C 17-20 lyase activity was absent. Cyp17a2 mRNA was expressed mainly in the head kidney, ovary, and testis, and quantitative PCR analysis demonstrated that expression in the ovary increased during induced vitellogenesis and oocyte maturation/ovulation. In contrast, P450c17-I showed both 17α-hydroxylase and C 17-20 lyase activities, and cyp17a1 expression increased until the mid-vitellogenic stage and remained high thereafter. Considering the high level of cyp17a2 transcript in the eel ovary at the migratory nucleus stage together with our previous report demonstrating that eel ovaries have strong 17α-P-to-DHP conversion activity, the failure of artificially maturing eels to produce the maturation-inducing DHP may be explained by a deficiency in 17α-P production due to the persistence of cyp17a1 expression after the completion of vitellogenesis. [ABSTRACT FROM AUTHOR]

Perylene and benzo[ a ]pyrene concentration changes during the gradual increase of thermal maturity have been analyzed for the Palaeogene Podhale flysh deposits and other Palaeozoic to Cenozoic sedimentary rock samples. Perylene is present in high relative concentration in the samples of maturation below 0.6% of the vitrinite reflectance (R r ), while in the range of 0.6%–0.7% R r its abundance rapidly decreased. In the case of samples with vitrinite reflectance higher than 0.7% R r , perylene compound disappeared completely. Benzo[ a ]pyrene is also thermally unstable at elevated temperatures and its relative concentration is very low above vitrinite reflectance values of ca. 0.9%. Such results could have important palaeoenvironmental implications. If these five-ring polycyclic aromatic hydrocarbon compounds are characterized by low to moderate thermal stability, then their use as a wood-degrading fungi tracer in the case of perylene and palaeo-wildfire indicator in the case of benzo[ a ]pyrene is limited only to samples of maturation below the oil window range and below the major phase of oil generation, respectively. These results explain the scarcity of perylene in Palaeozoic sedimentary rocks, which are generally of higher maturation than the younger deposits. [ABSTRACT FROM AUTHOR]

The European eel is a critically endangered species that cannot be reproduced in captivity yet. Artificial maturation of female European eels can be achieved via a laborious and expensive procedure, including weekly injections with pituitary extracts for up to 6 months. The success rate is highly variable and a minimally invasive method for early selection of responsive eels would prevent the unnecessary and lengthy treatment of non-responding individuals. Since sexual maturation of European eels is accompanied by morphological changes of the pectoral fin, we examined whether fin could be used to monitor the response to the hormone treatment. Farmed eels were subjected to weekly injections with pituitary extracts and representative groups were sampled at 0 and 14–18 weeks of hormone treatment. Responders and non-responders were identified based on the gonado-somatic index. Transcriptomes of pectoral fin samples obtained at the start and end of the trial were mapped using Illumina RNAseq. Responders showed 384 and non-responders only 54 differentially expressed genes. Highly stringent selection based on minimum expression levels and fold-changes and a manual re-annotation round yielded 23 up-regulated and 21 down-regulated maturation marker genes. The up-regulated markers belong to five categories: proteases, skin/mucus structural proteins, steroid hormone signaling, tyrosine/dopamine metabolism and lipid metabolism. The down-regulated markers are either blood markers or lectin-related genes. In conclusion, pectoral fin transcriptomes are a rich source of indicator markers for monitoring hormone induced sexual maturation of female European eels. In addition, these markers provide important new insight into several fundamental processes in eel biology. [ABSTRACT FROM AUTHOR]

Highlights: [•] Сobs decreases during the artificial maturation experiments. [•] Branched aromatic carbons transform into bridgehead aromatic carbons. [•] –(CH2)–O–C structures in kerogen break up at the early stages of catagenesis. [•] The spatial remoteness of alkyl chains from aromatic cores is fixed up to the oil window. [ABSTRACT FROM AUTHOR]

The high adsorption capacity of peat for heavy metals constitutes a complex phenomenon of economic and environmental interest. Nevertheless, little is known about how this process is modified by enhancing the thermal maturity of the peat, as a consequence of the burial of the peat-bog. The aim of this study is the evaluation of the variability in the capacity of adsorption of the peat for the ions Cu++, Cd++ and Zn++ according with the thermal maturity increases, by means of artificial maturation in the laboratory. The adsorption isotherms were determined in both the original and artificial matured peat, from the peat-bogs of Cuare swamp (Falcon State, Venezuela). Notable decrease is observed in the matured peat for all studied ions, with respect to the original peat. The affinity order for metals towards the carbonaceous materials used was Cu2+> Zn2+> Cd2+.

This study aimed to describe the response variability of female silver eels in terms of gonad development and eggs production to a standardized gonadotropic treatment (Carp pituitary extracts-CPE), and to relate this variability to population characteristics. For this purpose, sexual maturation, ovulation, and fertilization were induced in two eel populations coming from different locations in Adriatic Sea ( Comacchio-CM and Marano- Grado-MG lagoons), and after that, their reproductive capacity was valuated. External (Silver index-SI, Eye index-EI, Pectoral fin length index-PFLI, Condition factor-K) and hormonal (17β-estradiol-E2, testosterone-T) parameters were measured, and some subject/group were killed for histological and lipid analysis and age determination. Morphometric parameters showed the CM-Group to have highest values of Body weight (BW), Body length (BL), and K, while MG-Group presented highest PFLI and Gonadosomatic index (GSI) values. Regarding hormonal analysis, the CM-Group showed significantly higher T and E2 levels than the MG-Group, both groups showed considerably rapid increase at T5 (5th injection). A positive trend in gonadal development was found through histological evaluation; a more regular maturation was observed in the MG-Group, whereas the CM-Group presented an exponential oocytes development starting from T10 (10th week), which led to an anticipated spawning. Lipid content showed significant differences in T0 (start study), post-ovulation, and Control (30th week) between CM and MG eels. As to zootechnical performances, while MG eels released spontaneously into the water, the CMs were stripped in order to check ovulation. The MG eels were statistically the most productive with 40.1 ± 6.33 % BW of eggs released. Furthermore, CM females ovulated mainly between the 19th and 22nd week (77.8 % spawned eels) instead in the MG's ovulation goes from the 24th to the 28th week (100 % spawned eels). As fertilization is of concern, in both groups fertilized eggs were obtained with no difference in larvae production. These results seem to indicate that bigger dimensions, higher K, and larger lipid content (Comacchio eels) could fasten gonadic maturation without positively influencing reproductive performance of animals, both in term of quantity and quality of produced eggs. Smaller females with a highest SI (Marano-Grado eels) presented a more regular gonadic development, leading the animals to spontaneous spawning. [ABSTRACT FROM AUTHOR]

Highlights: [•] The first direct low field NMR measurements were made upon kerogen. [•] Solid echoes recover signal lost in shales from homonuclear dipolar coupling. [•] NMR responses agree with the properties of shale at differing maturities. [•] Solid echo techniques can potentially distinguish liquids and solids in shales. [ABSTRACT FROM AUTHOR]

Sexual maturity was induced in wild silver eel females of the European eel (Anguilla anguilla) using a protocol similar to that successfully used for Anguilla japonica. Eels were injected for sixteen weeks with increasing doses of carp pituitary extract (10, 20, 30, and 40 mg CPE/kg body wt) and kept in natural light or completely dark conditions. In both groups, final oocyte maturation and ovulation were induced by injection of 17,20 h-dihydroxy-4-pregnen-3-one (DHP) at 2 mg/g body wt. All sixty eels turned out to be silver and actively migrant (58 in stage V and two in stage IV), showing a particularly high eye index (15.75±1.40), and distributed within three age classes (7-9 years). In the group kept in darkness, one of the four females ovulated 12 h after DHP injection in the thirteenth week. The remaining three females received the final (16th) CPE injection and ovulated 12-36 h after the DHP injection. In the group kept in light, two of the four females received the 16th CPE injection and ovulated 12-36 h after the DHP injection; the remaining two did not ovulate within 36 h post DHP injection. The total number of eggs released by the group kept in darkness (1,485,600) was significantly higher than that of the group kept in light (274,000). There was no mortality during the experiment. [ABSTRACT FROM AUTHOR]

Abstract: In order to improve the hatching rate of eggs from artificially matured female eels, the environmental temperature during late stages of oocyte development was lowered from 20°C (control) to 18°C. Thus, female eels in which artificial maturation was induced at 20°C using chum salmon pituitary extract (SPE) were transferred to water at either 20 or 18°C at the beginning of the late stage of maturation. Biopsy by cannulation was carried out on the basis of an increase in body weight index (BWI; BWI=body weight×100/initial body weight). If the eel was judged to be nearing final maturation, a priming dose of SPE was administered, followed by a dose of maturation-inducing hormone (MIH). The average hatching rates of the eggs from the eels maintained at 20 and 18°C were 16.6% (n =10) and 45.9% (n =11), respectively. The hatching rates at 18°C were significantly higher than those at 20°C. At 20°C, the optimal timing of cannulation may often be missed due to both the rapid rate of oocyte development in the late stage and the unreliability of the BWI-based timing criterion. At 18°C, rapid development of maturing oocytes in the late stage was prevented, and the optimal ovulation induction period was prolonged. Accordingly, the likelihood for optimal timing of cannulation was increased, as reflected in high hatching rates of fertilised eggs. On the basis of these results, a temperature of 18°C in late stages of oocyte development is recommended to help in improving and stabilising the hatching rate. [Copyright &y& Elsevier]

Abstract: The main purpose of this contribution is to compare the ability of Carboniferous coals from the Donets Basin of the Ukraine and Cretaceous coal from the Sabinas Basin of the Mexico to generate hydrocarbon gases (C1–C5). Two bituminous coals from the Donets Basin (2c10YD and 1l1Dim; 0.55 and 0.65%R r respectively) and one bituminous coal from the Sabinas Basin (Olmos, 0.92%R r) were studied using heating experiments in a confined-pyrolysis system. The highest rank reached during the heating experiments corresponds to the anthracite stage (2.78 and 2.57%R r) for the 2c10YD and 1l1Dim coals and (2.65%R r) for the Olmos coal. The composition of the generated (C1–C5) gases was evaluated using a thermodesorption-multidimensional gas chromatography. The results show that the Carboniferous Donets coals produced more wet gas and methane during pyrolysis than the Cretaceous Olmos coal. This is probably due to their higher liptinite (6–20%) and collodetrinite content and to the loss of a major part of the petroleum potential of the Olmos coal during natural coalification. C2–C5 compounds are mainly derived from the cracking of liquid hydrocarbons. Ethane is the most stable compound and formed from the cracking of higher hydrocarbon component. Large amounts of methane (up to 81 mg/g coal for the Donets coals and 50 mg/g coal for the Sabinas coal) were formed at high temperatures by cracking of previously formed heavier hydrocarbons and by dealkylation of the coal matrix. A linear relationship was observed between methane generation and the maturity level of both coal types. [Copyright &y& Elsevier]

Abstract: The goal of this work is to study the ability of two immature Carboniferous coals from Donets Basin (Ukraine) to act as source for oil. Heating experiments in confined medium were performed to compare the thermal behavior of these coals, 1l1 Dim (%R r =0.55; H/C at.=0.79) and 2c10YD (%R r =0.65; H/C at.=0.80), relative to a mature Cretaceous coal from Sabinas Basin (Olmos, %R r =0.92, H/C at.=0.77). Macerals analysis carried out on starting materials showed that Olmos is exhausted in liptinite contrary to 2c10YD (20 vol.%) and 1l1Dim (6 vol.%). The vitrinite content is lower for 2c10YD (59 vol.%) than for Olmos (84 vol.%) and 1l1Dim (80 vol.%). Solid bitumen occurs often dispersed in the raw coals. Both petrographic and geochemical analyses on starting materials revealed that the selected Carboniferous Donets coals have better potentialities for bitumen generation than the Cretaceous Sabinas coal. The presence of long chain n-alkanes (> n-C8) in the pyrolysis-GC chromatograms indicates that the two raw Carboniferous coals from Donets Basin can yield non-volatile hydrocarbons under further thermal maturation. It is speculated that some vitrinite macerals present in hydrogen-rich Carboniferous coals from Donets Basin can act as source rocks for oil. As a matter of fact, results showed that the ‘oil window’ occurs between ∼1.0%R r and ∼2.0%R r for both Cretaceous Sabinas and Carboniferous Donets coals during confined pyrolysis. As expected from geochemical and petrographic analyses of starting samples, the Carboniferous Donets coals yielded more bitumen and hydrocarbons than Cretaceous Sabinas coal during artificial maturation. Low proportions of solid bitumen (<12 vol.%) are also formed between 1.1%R r and 1.5%R r during confined pyrolysis of coals. Two solid bitumen groups have been identified, which correspond to distinct phases of neo-formation. The drop in the solid bitumen content at higher ranks indicates that it contributes to generation of gas during experimental simulation. Moreover, their morphology and porosity change with the level of maturity. The porosity of the vitrinite matrix increases as well as the pore size with increasing maturity. A relationship has been observed between the porosity and the weight loss: the higher pore content of Carboniferous Donets coals is correlated with a higher generation of gas compared to Cretaceous Sabinas coal. [Copyright &y& Elsevier]

Abstract: Recombinant Japanese eel follicle-stimulating hormone (rjeFSH) produced by methylotrophic yeast was subjected to in vivo bioassay to assess its gonadotropic activities and availability to artificially induce maturation of this species. Intramuscular injections of rjeFSH into male eels at doses of 0.1 and 1.0 U/g body weight were repeated 3 times during 12 days. The rjeFSH significantly increased plasma 11-ketotestosterone levels, and induced both testicular growth and spermatogenesis in a dose-dependent manner. These results demonstrate that rjeFSH is effective in promoting male eel gamatogenesis in vivo. Instead of scarce native eel FSH, abundant recombinant eel FSH is now ready for future application to maturation induction of Japanese eel. [Copyright &y& Elsevier]

Abstract: Vitellogenin (Vtg), the precursor molecule for yolk, is synthesized in the liver under estrogenic control. In all oviparous species, including fish, the process of vitellogenesis is crucial to subsequent embryonic development. This study attempted to obtain the cDNA encoding for Vtg from female Japanese eels, Anguilla japonica. Rapid amplification of cDNA ends (RACE) and polymerase chain reaction (PCR) were used to amplify Vtg cDNA prepared from liver extracts. Obtained PCR products were subcloned and sequenced. The overall sequence of eel Vtg cDNA isolated in this study contained 5395bp nucleotides. This Vtg sequence encodes 1743 amino acids of the precursor molecule, and is entirely composed of the characteristic N-terminal lipovitellin-I region, an internal polyserine domain region, and a c-terminal lipovitellin-II region. The deduced amino acid sequence from these clones shares 34–61% identity with other teleost Vtgs. Northern blot assays of Vtg gene expression following hormonal treatment demonstrated that this Vtg is synthesized in the liver under stimulation by estradiol injection. However, Vtg synthesis may not be enhanced by salmon pituitary homogenate (SPH) induction for the developing ovarian follicles. Notably, the effect of methyltestosterone, following SPH injection, may be more appropriate for the uptake of Vtg by ovarian follicle maturation during the artificial maturation of Japanese female eels. [Copyright &y& Elsevier]

Abstract: The objective of this work is to estimate the hydrocarbon production in the Central Asturian Coal Basin (NW Spain) by using the results of artificial maturation and the numeric maturation modeling taking into account the thermal evolution of the maceral composition, the vitrinite reflectance, the T max, and the gas production. A confined pyrolysis was carried out inside gold cells under a pressure of 700bar at several temperatures (330, 360 and 400°C) and duration (24, 120 and 720h). The kinetic model METAGAZ-1D was used to simulate hydrocarbon production. Methane production begins at %R r =0.7 and increases with reflectance. Vitrinite reflectance, and T max were calculated from the model by describing the kerogen transformation under the action of typical temperature of burial. From the spatial distribution of the vitrinite reflectance, and after the depth, the importance of the hydrocarbon production was estimated by the simulation and artificial maturation and compared with the gas quantities adsorbed by coal. Two mechanistic pathways relating to CH4 production and CH4 adsorption from coal were built to estimate the real exploitable gas proportion as function of depth and the geographical location of the coal seams in the basin. [Copyright &y& Elsevier]

Abstract: The objective of this work is to estimate the hydrocarbon production in the Central Asturian Coal Basin (NW Spain) by using: [•] the maturation simulation of the coal in laboratory by confined pyrolysis, and [•] the study of the petrographic (%R r ), geochemical (T max) and molecular changes during the artificial maturation process. Confined pyrolysis was carried out inside gold cells under a pressure of 700bar at several temperatures (330, 360 and 400°C) and durations (24, 120 and 720h). Artificial maturation from lower to higher temperature showed an evolution of macerals by comparing the raw coal and the solid residues after the pyrolysis. The vitrinite content increases and the inertinite and liptinite contents decrease. The porosity also increases with an increase of the pore size and eventually, coalesces. The vitrinite reflectance (%R r ) increases from 0.78 for the raw sample to 2.98 for the solid residues at 400°C. Organic geochemical parameters exhibit a similar trend with an evolution from oil window to the gas window. HI and T max of original coals of this basin indicate a predominant gas- to oil-proneness. A decrease of total extract yields and changes in aliphatics, aromatics and polars contents is also showed by increasing maturation. Aromatization reactions transform aliphatic and polar molecules at high temperature. [Copyright &y& Elsevier]

The eel has long been esteemed as an important food fish in the world, especially in Japan, and has been used as an experimental fish for many fields of fish physiology. However, the decreases in eel resources have been a serious concern in recent years. The catches of glass eels as seedlings for aquaculture have shown a long-term decrease in both Europe and East Asia. To increase eel resources, the development of techniques for artificial induction of maturation and spawning and rearing their larvae have been eagerly desired. Recent progress of reproductive physiology of fish, especially mechanisms of oocyte maturation and ovulation in female and of spermatozoa maturation in male, facilitate to establish techniques for hormonal induction of maturation and spawning in sexually immature eels. With persistent effort to development of rearing techniques of larvae, we have first succeeded to produce glass eel. These applied techniques are may contribute to understand the basic reproductive physiology of the eel. [ABSTRACT FROM AUTHOR]

Abstract: To investigate whether steroid profiles in salmon pituitary homogenate (SPH)-induced artificially maturing Japanese eel, Anguilla japonica, resemble those in other, naturally maturing fishes, the daily changes in 11 steroids were analyzed for a 70-day period (average time needed to reach the maturational phase). Concentrations of most steroids were low and changed on a weekly basis, with maximum values 2–5 days after an SPH injection. Thus, pregnenolone, 17α-hydroxypregnenolone, dehydroepiandrosterone, progesterone, 17α-hydroxyprogesterone, 17α,20 β-dihydroxy-4-pregnen-3-one, androstenedione and estrone levels were barely or not detectable in serum throughout the experimental period, which is largely in keeping with what is known about oogenesis-related steroids in other fishes. In contrast, serum testosterone (T) levels were high, but fluctuated considerably with each SPH injection (about 0.3–8.3 ng/ml). The serum estradiol-17β (E2) levels increased after SPH injections and gradually rose throughout the experiment, peaking at the end of the experimental period (about 0.2–7.8 ng/ml). Serum levels of 11-ketotestosterone (11-KT) before SPH treatment were higher (approximately 2 ng/ml) than those of the other steroid hormones (less than 0.5 ng/ml). 11-KT levels increased gradually over the experimental period, and, like E2, levels peaked towards the end of the experimental period (about 15 ng/ml). The observed patterns for T, E2 and 11-KT are unlike those in other fishes. Furthermore, the consistent elevations in levels of 11-KT, both before and after SPH treatment, are suggestive of an important role for this steroid in controlling oocyte growth. [Copyright &y& Elsevier]

Morphological changes in the oocytes of the Japanese eel, Anguilla japonica, induced to undergo ovarian development by repeated injections of salmon pituitary homogenate, were examined using electron microscopy. Oil droplets were closely associated with organelles, especially mitochondria, and increased in number as oocyte growth proceeded. They fused at the migratory nucleus stage. During vitellogenesis, two types of cortical alveoli were distinguished, one having filamentous contents, the other having latticated contents. As oocytes reached maturity, the structure of the cortical alveoli was exclusively filamentous. Yolk globules were homogeneous and highly electrondense, but electrondensity decreased during hydration. The structure of the zona radiata of previtellogenic oocytes consisted of two layers, and an additional reticular network structure was formed on the inside of the zona radiata during the vitellogenic stage. The zona radiata lost the reticular network structure and assumed a layered structure of uniform electrondensity at the migratory nucleus stage. These structural changes during oocyte development were mostly comparable to those in other teleosts. Results of the present study should assist in developing improved methods for full control of artificial maturation in the Japanese eel. [ABSTRACT FROM AUTHOR]

To investigate transcription of pituitary glycoprotein hormone a and gonadotropin IIβ (GTH IIβ) subunits in female Japanese eel, gene quantitation systems using reverse transcription-polymerase chain reaction (RT-PCR) were developed, using β-actin as an internal control gene. These systems were not only sensitive, but also precise, with low coefficients of variation within and between assays (below 20 and 30%, respectively). Using these quantitation systems, we investigated how transcription of both subunits changed in Japanese eel during ovarian development induced by repeated injections of salmon pituitary homogenate (SPH). Transcriptional level of pituitary glycoprotein hormone α was similar to that of ß-actin before SPH injection, and increased slowly during ovarian development, reaching a maximum (3-fold increase over initial levels) at the migratory nucleus stage. In contrast, the level of GTH IIβ mRNA was very low (about one-tenth that of β-actin) before SPH injection, but expression increased markedly during ovarian development with an approximate 120-fold increase over initial levels (12 times that of β-actin) at the migratory nucleus stage. These results suggest that GTH II synthesis in female eel was activated during ovarian development induced by repeated SPH injections. The increase in mRNA levels of both subunits mRNA is probably due to sex steroids produced in eel ovarian follicles. Unexpectedly, transcriptional level of GTH IIβ was abnormally high compared to that of pituitary glycoprotein hormone α at the migratory nucleus stage. These results suggest that repeated SPH injections induced aberrant endocrine conditions in female Japanese eels. [ABSTRACT FROM AUTHOR]

• Raman parameters of Pd and D(d–g) are excellent maturity indexes for coal geological samples. • A coal sample and two oil prone kerogens were matured artificially. • Pd and D(d–g) also could be taken as maturity parameters of pyrolysis residues. • Two chart curve were proposed to scale maturity of oil prone OM by using Pd and D(d–g). Thermal maturity determination for oil prone organic matter (OM) is a very important and difficult work, especially for the source rock with vitrinite absence. In this study, vitrinite reflectance and Raman spectroscopy of 23 coal samples with maturity ranged from 0.55%R o to 5.32%R o were measured. The authors proposed that Raman parameters of band D position (Dp) and the distance between bands D and G (D–G) are excellent maturity indexes. A coal sample and two oil prone kerogens of low maturity were matured artificially by heating in gold tube system. The maturities of pyrolysis residues at different pyrolysis temperature were determined by comparing the Raman maturity parameters between of geological and artificial matured coal samples. The pyrolysis residues of oil prone kerogen share a same maturity as that of coal at corresponding pyrolysis temperature as they were heated in same pyrolysis condition. On the base of these works, two equations to determine the maturity of oil prone OM were set up by using Raman maturity parameters of Dp and D-G. [ABSTRACT FROM AUTHOR]

La elevada capacidad de adsorción de la turba hacia los metales pesados, constituye un fenómeno complejo de interés económico y ambiental. Sin embargo, no se conoce con claridad cómo es modificado este proceso acorde incrementa la maduración de la turba, por efecto del soterramiento en las turberas. El propósito de este trabajo es evaluar la capacidad de adsorción de la turba hacia los iones Cu2+, Cd2+ y Zn2+ a medida que incrementa el proceso de maduración térmica, inducida por hidropirólisis en el laboratorio. Fueron determinadas las isotermas de adsorción de los iones citados en turba original proveniente de las turberas de manglar de Cuare (Estado Falcón, Venezuela), así como su producto madurado artificialmente. La turba madurada disminuye notablemente su capacidad de adsorción de todos los iones estudiados, con respecto al material original. El orden de afinidad de los metales hacia los materiales carbonáceos usados fue Cu2+> Zn2+> Cd2+.