•Melatonin receptors type 1A/B are expressed in bovine preantral and antral follicles.•Melatonin stimulates follicle growth through its membrane receptors.•Luzindole blocks the effects of melatonin ...on follicle growth.•Luzindole blocks the effects of melatonin on expression of antioxidant enzymes.
This study aims to investigate the (1) expression of melatonin receptors types 1A/B (MTNR1A/B) in bovine ovaries and (2) the in vitro effects of melatonin on secondary follicle development, antrum formation, viability, and expression of messenger ribonucleic acid (mRNA) for superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase-1 (GPX1) and peroxiredoxin 6 (PRDX6). The expression of MTNR1A/B in bovine ovarian follicles was demonstrated by immunohistochemistry. To choose the most effective concentration of melatonin on follicular growth and viability, isolated secondary follicles were cultured individually at 38.5°C, with 5% CO2 in air, for 18 d in TCM-199+ alone or supplemented with 10−11, 10−9, 10−7 or 10−5 M melatonin. Then, melatonin receptor antagonist, luzindole, was tested to further evaluate the mechanisms of actions of melatonin, that is, the follicles were cultured in control medium alone or supplemented with 10−7 M melatonin, 10 µM luzindole and both 10−7 M melatonin and 10 µM luzindole. Follicular growth, morphology and antrum formation were evaluated at days 6, 12 and 18. At the end of culture, viability of secondary follicles was analyzed by calcein-AM and ethidium homodimer-1, and the relative levels of mRNA for SOD, CAT, GPX1 and PRDX6 were evaluated by real time polymerase chain reaction. Immunohistochemistry results showed expression of MTNR1A/B in oocyte and granulosa cells of primordial, primary, secondary and antral follicles. Secondary follicles cultured in medium supplemented with melatonin at different concentrations had well preserved follicles after 18 d of culture. Furthermore, follicles cultured in presence of 10−7 M melatonin presented significantly higher diameters than those cultured in other treatments. The presence of melatonin receptor antagonist, luzindole, blocked the effects of melatonin on follicular growth and viability. In addition, follicles cultured in medium containing only melatonin had significantly higher rates of antrum formation. Follicles cultured in medium containing only melatonin had higher relative levels of mRNA for CAT, SOD and PRDX-6 than those cultured with both melatonin and luzindole. Follicles cultured with luzindole only or both melatonin and luzindole had lower relative levels of mRNA for PRDX6 and GPX1 than those cultured control medium. In conclusion, melatonin promotes growth of bovine secondary follicles through its membrane-coupled receptors, while luzindole blocks the effects of melatonin on follicle growth and reduces the expression of antioxidant enzymes in cultured follicles.
Intensity mapping provides a unique means to probe the epoch of reionization (EoR), when the neutral intergalactic medium was ionized by energetic photons emitted from the first galaxies. The C ii ...158 m fine-structure line is typically one of the brightest emission lines of star-forming galaxies and thus a promising tracer of the global EoR star formation activity. However, C ii intensity maps at 6 z 8 are contaminated by interloping CO rotational line emission (3 ≤ Jupp ≤ 6) from lower-redshift galaxies. Here we present a strategy to remove the foreground contamination in upcoming C ii intensity mapping experiments, guided by a model of CO emission from foreground galaxies. The model is based on empirical measurements of the mean and scatter of the total infrared luminosities of galaxies at z < 3 and with stellar masses M * > 10 8 M selected in the K-band from the COSMOS/UltraVISTA survey, which can be converted to CO line strengths. For a mock field of the Tomographic Ionized-carbon Mapping Experiment, we find that masking out the "voxels" (spectral-spatial elements) containing foreground galaxies identified using an optimized CO flux threshold results in a z-dependent criterion m K AB 22 (or M * 10 9 M ) at z < 1 and makes a C ii/COtot power ratio of 10 at k = 0.1 h/Mpc achievable, at the cost of a moderate 8% loss of total survey volume.
Coralsnakes of the genus Micrurus are a diverse group of venomous snakes ranging from the southern United States to southern South America. Much uncertainty remains over the genus diversity, and ...understanding Micrurus systematics is of medical importance. In particular, the widespread Micrurus nigrocinctus spans from Mexico throughout Central America and into Colombia, with a number of described subspecies. This study provides new insights into the phylogenetic relationships within M. nigrocinctus by examining sequence data from a broad sampling of specimens from Mexico, Guatemala, Honduras, Nicaragua, Costa Rica, and Panama. The recovered phylogenetic relationships suggest that M. nigrocinctus is a species complex originating in the Pliocene and composed of at least three distinct species-level lineages. In addition, recovery of highly divergent clades supports the elevation of some currently recognized subspecies to the full species rank while others may require synonymization.
Plastic debris has been recognised as a potential stressor for Antarctic marine organisms. In this study, the effects of surface charged polystyrene nanoparticles (PS NPs) on the immune cells ...(coelomocytes) of the Antarctic sea urchin
Sterechinus neumayeri
were assessed through in vitro short-term cultures. The behaviour of anionic carboxylated (PS-COOH) and cationic amino-modified (PS-NH
2
) NPs in filtered natural sea water (NSW) from King George Island (South Shetland Islands) was characterised by dynamic light scattering. Cellular morphology, NP uptake, phagocytic capacity and gene expression were evaluated after 6 and 24 h of exposure to 1 and 5 µg mL
−1
PS NPs. Secondary characterisation showed an initial good dispersion of PS NPs in NSW, followed by nano-scale aggregation after 24 h. Both PS NPs affected cellular phagocytosis and generated an inflammatory response against oxidative stress and apoptosis at the molecular level. Fluorescently labelled PS-COOH aggregates were internalised by phagocytes and associated to the modulation of genes related to external challenges, antioxidant responses and cell protection against stress and apoptosis. Exposure to PS-NH
2
caused a strong decrease in phagocytic capacity and the formation of cellular debris at 5 µg mL
−1
after 24 h, but low gene modulation, suggesting a threshold in coelomocytes defence ability against PS-NH
2
. This study represents the first attempt to assess the impact of nanoplastics on Antarctic marine organisms. Our findings demonstrate that PS NPs with different surface charges constitute a challenge for
S. neumayeri
immune cells.
We report the capture of ppm-level aqueous perchlorate in record capacity and kinetics via the complete anion exchange of a cationic metal-organic framework. Ambient conditions were used for both the ...synthesis of silver 4,4'-bipyridine nitrate (SBN) and the exchange, forming silver 4,4'-bipyridine perchlorate (SBP). The exchange was complete within 90 min, and the capacity was 354 mg/g, representing 99% removal. These values are greater than current anion exchangers such as the resins Amberlite IRA-400 (249 mg/g), Purolite A530E (104 mg/g), and layered double hydroxides (28 mg/g). Moreover, unlike resins and layered double hydroxides, SBN is fully reusable and displays 96% regeneration to SBN in nitrate solution, with new crystal formation allowing the indefinite cycling for perchlorate. We show seven cycles as proof of concept. Perchlorate contamination of water represents a serious health threat because it is a thyroid endocrine disruptor. This noncomplexing anionic pollutant is significantly mobile and environmentally persistent. Removal of other anionic pollutants from water such as chromate, pertechnetate, or arsenate may be possible by this methodology.
Electrochemical concentration cell ozonesonde measurements are an important source of highly resolved vertical profiles of ozone with long-term data records for deriving ozone trends, model ...development, satellite validation, and air quality studies. Ozonesonde stations employ a range of operational and data processing procedures, metadata reporting, and instrument changes that have resulted in inhomogeneities within individual station data records. A major milestone is the first reprocessing of seven Southern Hemisphere ADditional OZonesondes (SHADOZ) station ozonesonde records to account for errors and biases in operating/processing procedures. Ascension Island, Hanoi, Irene, Kuala Lumpur, La Reunion, Natal, and Watukosek station records all show an overall increase in ozone after reprocessing. Watukosek shows the largest increase of 9.0 plus or minus 2.1 Dobson Units (DU) in total column ozone; Irene and Hanoi show a 5.5 plus or minus 2.5 DU increase, while remaining sites show statistically insignificant enhancements. Negligible to modest ozone enhancements are observed after reprocessing in the troposphere (up to 8%) and stratosphere (up to 6%), except at La Reunion for which the application of background currents reduces tropospheric ozone (2.1 plus or minus1.3 DU). Inhomogeneities due to ozonesonde/solution-type changes at Ascension, Natal, and La Reunion are resolved with the application of transfer functions. Comparisons with EP-TOMS, Aura's Ozone Monitoring Instrument and Microwave Limb Sounder (MLS) satellite ozone overpasses show an overall improvement in agreement after reprocessing. Most reprocessed data sets show a significant reduction in biases with MLS at the ozone maximum region (50-10 hPa). Changes in radiosonde/ozonesonde system and nonstandard solution types can account for remaining discrepancies observed at several sites when compared to satellites.
Dietary supplementation with triglyceride tributyrin (TBT), a butyrate precursor, has been associated with beneficial effects on fish health and improvements in the ability of carnivorous fish to ...tolerate higher levels of plant-based protein. In this study, we aimed to investigate the effects of a plant-based diet supplemented with TBT on the structural diversity and putative function of the digesta-associated bacterial communities of rainbow trout (Oncorhynchus mykiss). In addition to this, we also assessed the response of fish gut digestive enzyme activities and chyme metabolic profile in response to TBT supplementation. Our results indicated that TBT had no significant effects on the overall fish gut bacterial communities, digestive enzyme activities or metabolic profile when compared with non-supplemented controls. However, a more in-depth analysis into the most abundant taxa showed that diets at the highest TBT concentrations (0.2% and 0.4%) selectively inhibited members of the Enterobacterales order and reduced the relative abundance of a bacterial population related to Klebsiella pneumoniae, a potential fish pathogen. Furthermore, the predicted functional analysis of the bacterial communities indicated that increased levels of TBT were associated with depleted KEGG pathways related to pathogenesis. The specific effects of TBT on gut bacterial communities observed here are intriguing and encourage further studies to investigate the potential of this triglyceride to promote pathogen suppression in the fish gut environment, namely in the context of aquaculture.
Many remote sensing‐based evapotranspiration (RSBET) algorithms have been proposed in the past decades and evaluated using flux tower data, mainly over North America and Europe. Model evaluation ...across South America has been done locally or using only a single algorithm at a time. Here, we provide the first evaluation of multiple RSBET models, at a daily scale, across a wide variety of biomes, climate zones, and land uses in South America. We used meteorological data from 25 flux towers to force four RSBET models: Priestley–Taylor Jet Propulsion Laboratory (PT‐JPL), Global Land Evaporation Amsterdam Model (GLEAM), Penman–Monteith Mu model (PM‐MOD), and Penman–Monteith Nagler model (PM‐VI). ET was predicted satisfactorily by all four models, with correlations consistently higher (R2>0.6) for GLEAM and PT‐JPL, and PM‐MOD and PM‐VI presenting overall better responses in terms of percent bias (−10<PBIAS<10%). As for PM‐VI, this outcome is expected, given that the model requires calibration with local data. Model skill seems to be unrelated to land‐use but instead presented some dependency on biome and climate, with the models producing the best results for wet to moderately wet environments. Our findings show the suitability of individual models for a number of combinations of land cover types, biomes, and climates. At the same time, no model outperformed the others for all conditions, which emphasizes the need for adapting individual algorithms to take into account intrinsic characteristics of climates and ecosystems in South America.
Key Points
Four remote sensing evapotranspiration (ET) models were evaluated using 25 flux towers from across South America
Performance of all models is reduced in dry environments
Comparisons with flux tower‐based ET showed that Global Land Evaporation Amsterdam Model and Priestley–Taylor Jet Propulsion Laboratory produced higher correlations whereas RMSE was similar for all models
The Taiamã Ecological Station (TES) is a federal conservation unit created in 1981 to preserve nature and to support scientific research. The TES is a river island delimited by a bifurcation of the ...Paraguay River, with a total area of 11,555 ha. It is located in the north of the Pantanal biome (16°51'S 57°35'W), and the area of TES is part of the Cáceres and Poconé municipalities of Mato Grosso state in Brazil. Several groups of animals have been studied within the TES; however, lists of any amphibian and reptile species have been compiled for this conservation unit. Our objective was to generate a list of amphibian and reptile species for the TES. TES macrohabitats include floating fields (batumes), flooded fields, monospecific forests (Erythrina fusca), lakes and polyspecific forests. Polyspecific forests (pioneer forests along rivers) were the study area because they have firm land areas in the dry season and an adequate environment for installing traps in the soil.
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► Syntheses of bis-pyridyl dithioether copper, iron and vanadium complexes. ► Application of the metal complexes in mild alkane C–H and O–H oxidations. ► High catalytic activity in ...the presence of certain acid additives. ► Effects of type and amount of acid promoter, oxidant and catalyst are reported. ► Solvent-free microwave-assisted oxidation of primary and secondary alcohols.
Reactions of 1,6-bis(2′-pyridyl)-2,5-dithiahexane (Py
2S
2) with different sources of Cu(II), Fe(II) and V(III) afford the corresponding novel complexes CuCl(Py
2S
2)Cl (
1), CuCl(Py
2S
2)(CuCl
2) (
1′), Cu(OTf)
2(Py
2S
2) (
2), Cu(Py
2S
2)(H
2O)
2(OTf)
2 (
2′), FeCl
2(Py
2S
2) (
3), Fe(Py
2S
2)(CH
3CN)
2SbF
6
2 (
4) and VCl
2(Py
2S
2)Cl (
5), bearing Py
2S
2 as a tetradentate ligand. All the compounds were characterised by IR, ESI–MS, elemental analyses and, in the cases of
1′,
2′ and
4, the molecular structures were also elucidated by single X-ray crystal diffraction analysis. Complexes
1–
5 were evaluated as catalysts or catalyst precursors for the mild peroxidative oxidation of cyclohexane in acetonitrile typically at 25
°C and in the solvent-free oxidation of primary and secondary alcohols under microwave (MW) irradiation. The influences of the type and amount of acid promoter, amounts of oxidant and catalyst, time and temperature, on the product yields and TONs, are investigated.
The iron(II) complexes
3 and
4 are the most active catalysts in the oxidation of cyclohexane with H
2O
2 in a slightly acidic medium, leading to maximum overall yields (based on the alkane) of 38 and 28%, and turnover numbers (TON) up to 950 and 1450, respectively.
Additionally, the Cu and Fe complexes (
1–
4) proved to be useful catalysts in various MW-assisted alcohol oxidations at 80
°C with
t-BuOOH. The oxidation of 1-phenylethanol catalysed by the Fe complex
3 in the presence of pyrazine-2-carboxylic acid (co-catalyst) is very fast, giving the acetophenone product (TOF
=
4470
h
−1) in good yield (75%) just after 5
min of reaction time.
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