Fish Eggs Research Articles

ISOLATION AND CHARACTERIZATION OF FUNGI ASSOCIATED WITH BODY AND EGG FROM DISEASED AFRICAN CATFISH, Clarias gariepinus

African catfish (Clarias gariepinus) are in high demand in the Malaysian market. However, these species are known to be easily infected with diseases such as fungi, which can cause mortality and economic losses. In addition, fungal infection in fish eggs can reduce their production. The objective of this study was to isolate and identify fungi from infected African catfish and their eggs. Symptoms include a swollen lesion, irregular swimming, darker discoloration, and screening of pathogenic fungi. Isolations, identifications, and extracellular enzymatic assays were performed for the isolated fungi. Potato dextrose agar was used as isolation medium for isolating fungi on African catfish and their eggs. Fungi were identified by macroscopic observation of growth morphology and their structure, followed by microscopic observation after staining with lactophenol cotton blue to observe hyphae. From the result, three fungi were isolated and identified as Mucor sp. (2n) and Trichoderma sp. (1n). All isolated fungi were also analyzed for extracellular enzymes such as proteases, amylases, and lipases to test their ability to produce them as pathogenic fungi. Trichoderma sp. showed positive results in all tests. However, one strain of Mucor sp. reacted positively to the amylase and lipase test, while the other strain of the same species showed no reaction, indicating a negative result. In conclusion, the isolated fungi have virulent properties and can cause mortality if the body and eggs are infected. Therefore, fish farms need comprehensive health management to prevent the spread of fungal diseases

DNA barcoding reveals cryptic diversity of fish eggs in Equatorial Southwestern Atlantic

DNA barcoding presents a reliable and universal tool for species identification; however, few studies have used this methodology to analyze fish egg diversity in low-latitude seascapes. In the present study, DNA barcodes were used to assess the diversity of fish eggs in the Equatorial Southwestern Atlantic, a rich but understudied region. We sampled two seascapes for analyzing the fish diversity: seagrass and rhodolith beds. Collectively, 112 fish eggs were sorted for genetic analysis, of which 31 were successfully sequenced. One egg was successfully identified at the order level, three at the family level, 20 at the genus level, and seven at the species level. Several tropical fish species have not yet been barcoded and deposited in genetic databases; therefore, our novel research has expanded our knowledge of the diversity of fish eggs in low-latitude areas. Molecular identification revealed a cryptic diversity among the types of eggs collected from major tropical seascapes. Importantly, efforts should be made to improve the barcode database for fish eggs and larvae worldwide. This baseline information is essential for assessing the global environmental changes affecting fish diversity in coastal seas.

Amazonian ichthyoplankton assessment via DNA metabarcoding: A baseline for detecting spawning sites of migratory fishes

The Neotropical fish fauna comprises approximately 6080 species, of which almost 3000 inhabit the Amazon River basin. However, the construction of hydroelectric dams has threatened this biodiversity by habitat fragmentation. To uncover the putative effect of river impoundment on migratory fish species, over 5400 eggs and larvae were collected from the Teles Pires River, including five tributaries and the hydroelectric reservoir, which were identified using the COI metabarcoding approach. Identification of early life stages allowed the detection of >40 fish species, including at least 27 migratory species. Fish eggs were assigned to nine families, 13 genera, and 23 species, whereas larvae were attributed to 12 families, 18 genera, and 34 species. Eggs and larvae of migratory fishes were primarily present in tributaries upstream of the dam, with fewer in the reservoir. A putative impact of the dam on the ichthyoplankton community was detected, with a significant difference found between the reservoir and tributaries for larval species richness (r = 0.822, p = 0.0211). In contrast, no significant difference was recovered among tributaries for both eggs (r = 0.213, p = 0.2657) and larvae (r = 0.378, p = 0.0696). However, a change in ichthyoplankton assemblage was observed between tributaries, as revealed by beta diversity analyses. These results highlight the potential of ichthyoplankton metabarcoding for studying and biomonitoring of migratory fishes, as well as providing relevant data concerning the identification of spawning sites to set guidelines for fisheries management and effective conservation of fish populations.

Gadusol is a maternally provided sunscreen that protects fish embryos from DNA damage

Exposure to ultraviolet radiation (UVR) is harmful to living cells, leading organisms to evolve protective mechanisms against UVR-induced cellular damage and stress.1,2 UVR, particularly UVB (280-320nm), can damageproteins and DNA, leading to errors during DNA repair and replication. Excessive UVR can induce cellulardeath. Aquatic organisms face risk of UV exposure as biologically harmful levels of UVB can penetrate >10m in clear water.3 While melanin is the only known sunscreen in vertebrates, it often emerges late in embryonic development, rendering embryos of many species vulnerable during the earlier stages. Algae and microbes produce a class of sunscreening compounds known as mycosporine-like amino acids (MAAs).4 Fish eggs contain a similar compound called gadusol, whose role as a sunscreen has yet to be tested despite its discovery over 40 years ago.5 The recent finding that many vertebrate genomescontain a biosynthetic pathway for gadusol suggests that many fish may produce and use this molecule as a sunscreen.6 We generated a gadusol-deficient mutant zebrafish to investigate the role of gadusol in protecting fish embryos and larvae from UVR. Our results demonstrate that maternally provided gadusol is the primary sunscreen in embryonic and larval development, while melanin provides modest secondary protection. The gadusol biosynthetic pathway is retained in the vast majority of teleost genomes but is repeatedly lost in species whose young are no longer exposed to UVR. Our data demonstrate that gadusol is a maternally provided sunscreen that is critical for early-life survival in the most species-rich branch of the vertebrate phylogeny.

The effect of papaya leaf extract (<i>Carica papaya</i>) with concentration on egg hatchability of nile tilapia (<i>Oreochromis niloticus</i>)

Delays in hatching of fish eggs are influenced by several factors such as water quality instability during rearing, including; temperature, DO, pH. Papaya leaf is one of the plants that can be used to accelerate the hatchability of fish eggs. Papaya itself can be used as a component to boost the immune system because it contains the enzyme papain. The purpose of this study was to compare the hatchability of nile tilapia (Oreochromis niloticus) eggs in the treatment of papaya leaf extract (Carica papaya) with different doses. This research was conducted at the Punten Cultivation Fisheries Installation, Batu City in December 2022. Using a Completely Randomized Design (CRD) where there were 4 treatments, namely: A) papaya leaf extract 4 mL/L, B) papaya leaf extract 6 mL/L, C ) papaya leaf extract 10 mL/L, and D) control without treatment. In each treatment there were 3 repetitions. The ANOVA test was used to compare the effect of papaya leaf extract on hatchability of tilapia eggs, and was followed up with the BNT test if there were significant differences in the treatments. The results showed that there were significant differences in the treatment with the addition of papaya leaf extract on the hatchability of tilapia eggs, with 4 mL/L treatment) being the best treatment in increasing the hatchability percentage of tilapia eggs by 88.33%. There is a tendency that the higher the papaya leaf extract, the egg hatchability decreases.

Effectiveness of Items of Jarak Leaf Extract (Jatropha Curcas) with Different Dosages to Prevent Attacks of Fungs Saprolegnia sp on Gold Fish (Cyprinus carpio L) EGGS

The aim of the study was to determine the effect and optimal dose on hatchability, hatching time and prevalence. The study was carried out in two stages, namely the manufacture of jatropha leaf simplicia dried using an oven at 70 oC for 5 minutes. Puree using a blender. Weighed according to the treatment, namely A 3 g/L, B 5 g/L, C 7 g/L and D 0 g/L. The next stage is spawning the broodstock, and selecting 2,400 eggs that have been successfully fertilized, each treatment with 200 eggs. Each treatment was soaked for 4 minutes. The eggs were transferred to a hatching container with a volume of 5 L of water. The experiment was conducted using an experimental method (CRD), the factor tested was the effectiveness of castor leaf extract with different doses on hatching time, hatchability and prevalence. The results of observations of hatching times have a different number of hatchings. Treatment 3g/L 5 grains, treatment 5g/L 3 grains, without soaking 1 grain with hatching time 30 hours after fertilization. The most eggs hatched at 42-54 hours in the 3g/L treatment 479 eggs and the lowest in the treatment without soaking 258 eggs. For treatment 5g/L 419 grains and treatment 7g/L 380 grains. The effectiveness of giving effect, prevalence and presentation of hatching eggs in the 3g/L treatment has a success rate of 5%, for hatching time of 30-52 hours, prevalence is 20.17% and percentage of hatching eggs is 79.83%.

Climate change effects on hatching success and embryonic development of fish: Assessing multiple stressor responses in a large-scale mesocosm study

Climate change threatens freshwater fish species due to predicted changes in thermal, sedimentary and hydrological properties of stream ecosystems. Gravel-spawning fish are particularly sensitive to such alterations as warming, higher inputs of fine sediment and low-flow all have potentially negative effects on the functionality of their reproductive habitat, the hyporheic zone. Multiple stressors can interact in synergistic and antagonistic manners, causing surprise-effects that cannot be predicted from the additive consideration of individual stressors. For obtaining reliable, yet realistic data on the climate change stressor effects warming (+3–4 °C), fine sediment (increase in <0.85 mm by 22 %) and low-flow (eightfold discharge-reduction), we constructed a unique large-scale outdoor-mesocosm facility consisting of 24 flumes to study individual and combined stressor responses in a fully-crossed, 3-way-replicated design. To acquire representative results reflecting individual susceptibilities of gravel-spawning fish species due to taxonomic affiliation or spawning seasonality, we studied hatching success and embryonic development in the three fish species brown trout (Salmo trutta L.), common nase (Chondrostoma nasus L.) and Danube salmon (Hucho hucho L.). Fine sediment had the most significant single negative effect on both hatching rates and embryonic development (−80 % in brown trout, −50 % in nase, −60 % in Danube salmon). When fine sediment was combined with one or both of the other stressors, we observed strongly synergistic stressor responses, being distinctly stronger in the two salmonid species than in the cyprinid nase. Danube salmon was most susceptible to synergistic effects due to warmer spring water temperatures exacerbating the fine sediment-induced hypoxia, hence leading to complete mortality of fish eggs. This study highlights that individual and multiple-stressor effects depend strongly on life-history traits of respective species and that climate change stressors have to be assessed in combination to obtain representative results due to the high level of synergisms and antagonisms detected in this study.

Spatial and seasonal distribution of fish eggs and larvae in one free-flowing river in the Neotropical savanna.

Reproduction is one of the most important biological aspects for the maintenance of viable populations and understanding the spatial and seasonal patterns in the reproduction of Neotropical fish is a point that still needs considerable investigation. In this study, the main aim was to reduce knowledge gaps concerning fish eggs and larvae distribution patterns. For this, we used the River Araguaia basin, one of the main hydrographic basins of the neotropical savanna, as focal point of study. Samplings of fish eggs and larvae were carried across the hydrological regime during flooding and drought events between December 2018 and July 2020 at 15 sites distributed along a 350 km stretch of the River Araguaia basin. Fish eggs and larvae were found in all sampling sites with the highest number of catches in the flood season. The fish larvae were represented by five orders, 22 families, and 22 at the genus or species level. Both environments, tributary and main channel of the River Araguaia, are important for fish reproduction, and no difference was found in the use between the main channel and the tributaries. The results showed that spatial factors are important to explain the change in larval composition, which may have a wide or restricted distribution related to specific habitats. The main factors related to the reproductive activity of fish in this region are the physical and chemical changes in the water that occur in the flood season. These results indicate that the River Araguaia basin has environmental integrity and provides favorable conditions for the reproductive activity of fish, including long-distance migratory species. Considering this, mitigate measures that guarantee the preservation of the natural flow are crucial for the maintenance of fish biodiversity. This article is protected by copyright. All rights reserved.

Quality of fish eggs and production of androgenetic and gynogenetic doubled haploids (DHs).

Induced development of haploid embryos (H) with only paternal (androgenesis) or maternal (gynogenesis) chromosomes requires irradiation of eggs before fertilization or activation of eggs with irradiated spermatozoa, respectively. To provide doubled haploids (DHs), androgenetic and gynogenetic haploid zygotes need to be subjected to the thermal or high hydrostatic pressure (HHP) shock to suppress the first mitotic cleavage and todouble paternal or maternal haploid set of chromosomes. Androgenesis and mitotic gynogenesis (mito-gynogenesis) result in the generation of fully homozygous individuals in a single generation. DHs have been utilized in selective breeding programs, in studies concerning the phenotypic consequences of recessive alleles and to evaluate the impact of sex chromosomes on the early ontogeny. Moreover, the use of DHs for the NGS approach radically improves de novo the assembly of the genomes. However, reduced survival of the doubled haploids limits the wide application of androgenotes and gynogenotes. The high mortality of DHs may be only partly explained by the expression of recessive traits. Observed inter-clutch variation in the survival of DHs developing in eggs originating from different females make it necessary to take a closer look at the quality of the eggs used during induced androgenesis and gynogenesis. Moreover, the developmental competence of eggs that are subjected to irradiation before fertilization in order to deactivate maternal chromosomes when undergoing induced androgenesis and exposed to the physical shock after fertilization that leads to the duplication of the zygotes in both mito-gynogenesis and androgenesis may be also altered as irradiation and sublethal values of temperatures and hydrostatic pressure are considered as harmful for the cell organelles and biomolecules. Here, recently provided results concerning the morphological, biochemical, genomic, and transcriptomic characteristics of fish eggs showing high and low competence for androgenesis and mito-gynogenesis are reviewed.

Development of an All-Marine 3D Printed Bioactive Hydrogel Dressing for Treatment of Hard-to-Heal Wounds.

Current standard wound care involves dressings that provide moisture and protection; however, dressings providing active healing are still scarce and expensive. We aimed to develop an ecologically sustainable 3D printed bioactive hydrogel-based topical wound dressing targeting healing of hard-to-heal wounds, such as chronic or burn wounds, which are low on exudate. To this end, we developed a formulation composed of renewable marine components; purified extract from unfertilized salmon roe (heat-treated X, HTX), alginate from brown seaweed, and nanocellulose from tunicates. HTX is believed to facilitate the wound healing process. The components were successfully formulated into a 3D printable ink that was used to create a hydrogel lattice structure. The 3D printed hydrogel showed a HTX release profile enhancing pro-collagen I alpha 1 production in cell culture with potential of promoting wound closure rates. The dressing has recently been tested on burn wounds in Göttingen minipigs and shows accelerated wound closure and reduced inflammation. This paper describes the dressings development, mechanical properties, bioactivity, and safety.

Laboratory studies of fish entrainment sampling using a screw centrifugal impeller pump

AbstractObjectiveRegulatory legislation in both the United States and Canada requires water users with medium to high intake volumes to monitor entrainment losses to determine effects and to assess potential mitigation strategies to reduce harm to fish. Recent studies have recommended the use of both increased sampling frequency and sampling volume to characterize fish entrainment for large power plants on the Great Lakes. There is little doubt that increasing the flow rate and volume of water collected for sampling reduces the uncertainty in estimates of annual entrainment. Depending on the type of pump and the pumping flow rate used for entrainment sampling, considerable damage to fish larvae can occur. A screw‐type centrifugal pump has many qualities that make it ideal for entrainment sampling, but it has not yet been used as a sampling device for fish entrainment applications at power plants or other large industrial water users. The objective of this study was to determine mortality of entrainable fish eggs and larvae due to passage through a screw‐type centrifugal pump.MethodsIn a laboratory setting, Lake Trout Salvelinus namaycush eggs and larvae, Lake Whitefish Coregonus clupeaformis eggs, and Rainbow Trout Oncorhynchus mykiss juveniles were passed through a screw‐type centrifugal pump at three treatment flow rates: 39.5, 47.3, and 59.1 m3/h. Fish and eggs were monitored for mortality posttreatment and again at 24 and 48 h.ResultAcross treatments, very few mortalities were observed. Species specific moralities were four larval Lake Trout, one Lake Whitefish egg, and one juvenile Rainbow Trout. No mortality was observed for Lake Trout eggs.ConclusionThe present study identified high egg and larval survival (≥99%) after passage through a screw‐type centrifugal pump. High survival reduces error associated with identification and counting of entrained organisms, which provides more accurate estimates of annual entrainment losses.

Multipath ecological influence of an iteroparous fish migration from Lake Biwa to an alluvial stream

Abstract An increasing number of studies describe the ecological influence of semelparous and iteroparous fish migrations on spawning streams. This influence consists of not only the carcasses of spent adults, but also the nutrients that they excrete subsidising stream communities. Given the complex food‐web structure of stream communities, which includes aquatic insects from various functional feeding groups, resource subsidies provided by migratory fishes should influence stream communities through multiple pathways. We evaluated the ecological influence of an iteroparous three‐lips fish (Opsariichthys uncirostris uncirostris) in a alluvial stream by treating fish weirs as large‐scale manipulative field experiments. Between fish‐bearing and fish‐free areas, we compared concentrations of nutrients and fine particulate organic matter (FPOM), and compared densities and stable isotopes of periphyton and benthic macroinvertebrates. The presence of the three‐lips increased the concentrations of ammonium, soluble reactive phosphorus, particulate organic carbon and nitrogen, and chlorophyll‐a densities by up to 2.7‐fold. The δ15N of FPOM and macroinvertebrates during the migratory season were 2.8–7.0‰ higher in the fish‐bearing area, indicating a greater contribution of fish‐derived organic matter. Three‐lips subsidised stream macroinvertebrates through multiple pathways: consumers fed on (1) periphyton increased by the fish nutrient subsidy, (2) fish‐derived organic matter (such as fish carcasses and eggs), and (3) FPOM with fragmented periphyton and fish‐derived organic matter constituents. Results showed that, given the complex food‐web structures in alluvial streams, migratory fish influence stream ecosystems in complex ways. Further studies of the ecological influence of migratory fishes in alluvial streams are needed.

Use of “demonstration farm” videos to affect attitude change toward animal welfare on beef, egg, and fish farms in China

“Demonstration farms” can disseminate knowledge on farming practices and help to promote animal welfare. When on-farm visits are impractical, remote demonstrations are a feasible alternative. This study used videos of higher welfare beef, fish and free-range egg farms in China. It aimed to determine whether the videos affected attitudes and intentions toward animal welfare and whether such videos are useful training tools. Participants indicated a high acceptability of demonstration farm videos for learning about their industry and the needs of animals. Videos shifted participant attitudes toward animal welfare, but only when actively engaged in rating the farm on specific characteristics. Attitude changes suggested participants gained a greater understanding of animal welfare, a greater intention to improve on-farm welfare, and more confidence in peer support for welfare innovations after viewing the video. The findings indicate videos of demonstration farms are useful for remote training but passive viewing may be insufficient to create change, and outcomes should be monitored for success.

Searching for hotspots of neustonic microplastics in the Canary Islands

In this study, we investigated the concentration, distribution, and characteristics of neustonic MPs in the Canary Islands, with a particular focus on the island leeward zones, where a high accumulation of floating marine microplastics is expected. Samples were collected with a manta net at 15 different sites from Alegranza to La Gomera during the IMPLAMAC expedition. The microplastic concentration in surface waters ranged from 0.27 MPs/m3 in Alegranza to 136.7 MPs/m3 in the south of Gran Canaria. The highest concentration of MPs found was due to the presence of a sea-surface slick, also called “marine litter windrow”, formed in the south of Gran Canaria. The most abundant zooplankton group in the neuston was copepods, except at the marine litter windrow where fish larvae and eggs predominated. This indicates that coastal areas where marine litter windrows are formed have a high risk of MP ingestion and potential adverse effects on biota.

Nile tilapia (Oreochromisniloticus) invasion impacts trophic position and resource use of commercially harvested piscivorous fishes in a large subtropical river

BackgroundAlthough freshwater ecosystems cover less than 1% of the earth's surface, they support extremely high levels of biodiversity and provide vital ecosystem services. However, due to the introduction of non-native fishes, aquatic ecosystem functioning has been altered, and in some cases, declined sharply. Quantifying the impacts of invasive species has proven problematic. In this study, we examined the relative trophic position of native piscivorous fishes to estimate the effects of invasive Nile tilapia on food webs in the downstream sections of an invaded large subtropical river, the Pearl River, China. Furthermore, we quantified how native piscivorous fish diets changed as the Nile tilapia invasion progressed.ResultsThe trophic position of the widely distributed and locally important economically harvested piscivorous culter fish (Culterrecurviceps), mandarinfish (Sinipercakneri), and catfish (Pelteobagrusfulvidraco) lowered significantly in the invaded Dongjiang River compared to an uninvaded reference Beijiang River. The lower trophic position of these piscivorous fishes was reflected by a major reduction in the proportion of prey fish biomass in their diets following the Nile tilapia invasion. Small fishes in the diet of culter fish from the reference river (33% small fishes, 17% zooplankton) shifted to lower trophic level zooplankton prey in the invaded river (36% zooplankton, 25% small fish), possibly due to the presence of Nile tilapia. Additionally, small fishes in the diet of mandarinfish in the reference river (46% small fishes, 11% aquatic insects) declined in the invaded river (20% aquatic insects, 30% small fishes). Similarly, the diet of catfish from the reference river shifted from fish eggs (25% fish eggs, 25% aquatic insects) to aquatic insects in the invaded river (44% aquatic insects, 5% fish eggs).ConclusionsThe results of this study contributed to a growing body of evidence, suggesting that Nile tilapia can modify trophic interactions in invaded ecosystems. It is crucial to understand the processes outlined in this study in order to better assess non-native aquatic species, conserve the stability of freshwater ecosystems, and improve current conservation strategies in reaches of the Pearl River and other similar rivers that have experienced invasions of non-native species.

Geochemistry and mineralogy of fly ash from the high-alumina coal, Datong Coalfield, Shanxi, China

The abundance and distribution of minerals and elements in high-alumina coal fly ash (HACFA) is the basis for evaluating the resource utilization potential of HACFA and the key to developing a rare element extraction process. The geochemistry and mineralogy of HACFA were investigated by using alkali desilication and particle size screening, combined with multiple analytical techniques. As fly ash particles become finer, the content of mullite decreases, the content of quartz, corundum, and glass increases, and the content of hematite decreases first and then increases. The molecular structure of the glass phase is silicon-oxygen tetrahedron Q4(0Al). Minerals containing REE appear in the shape of fish eggs or oolitic particles, mainly composed of Ai, Si, REE, O. The maximum contents of Al, Li, Ga, and REE in HACFA are 67.65%, 240.57 μg/g, 77.97 μg/g, and 672.95 μg/g, showing a high utilization potential. However, the high contents of harmful elements Cd and Cr need special attention. Most of the trace elements in HACFA mainly reside in the glass phase. The iron-rich minerals are the main carriers of the ferrophilic elements Fe, Zn, Cr, Co, Mn, and Mg. The oxyphilic elements Al, Sc, Ta, Nb, and Ga mainly occur in corundum or mullite.

Metabarcoding of ichthyoplankton communities associated with a highly dynamic shelf region of the southwest Indian Ocean.

Drifting fish eggs and larvae (ichthyoplankton) can be identified to species using DNA metabarcoding, thus allowing for post hoc community analyses at a high taxonomic resolution. We undertook a regional-scale study of ichthyoplankton distribution along the east coast of South Africa, focused on the contrasting environments of the tropical Delagoa and subtropical Natal Ecoregions, and on exposed and sheltered shelf areas. Zooplankton samples were collected with tow nets at discrete stations along cross-shelf transects (20-200 m depth) spaced along a latitudinal gradient that incorporates a known biogeographical boundary. Metabarcoding detected 67 fish species, of which 64 matched prior distribution records of fishes from South Africa, with the remaining three known from the Western Indian Ocean. Coastal, neritic and oceanic species were present, from epi- and mesopelagic to benthopelagic and benthic adult habitats. By family, Myctophidae (10 species), Carangidae, Clupeidae, Labridae (each with 4 species) and Haemulidae (3 species) were most speciose. Ichthyoplankton community composition varied significantly with latitude, distance to coast, and distance to the shelf edge. Small pelagic fishes had the highest frequency of occurrence: Engraulis capensis, Emmelichthys nitidus and Benthosema pterotum increased in frequency towards the north, whereas Etrumeus whiteheadi increased towards the south. Chub mackerel Scomber japonicus accounted for most variability related to distance from the coast, whilst African scad Trachurus delagoa correlated with distance to the shelf edge. Dissimilarity between communities in the Delagoa and Natal Ecoregions was 98-100%, whereas neighbouring transects located within the sheltered KwaZulu-Natal Bight had lower dissimilarity (56-86%). Onshore transport of ichthyoplankton by Agulhas Current intrusions plausibly explained the abundance of mesopelagic species over the shelf. Metabarcoding followed by community analysis revealed a latitudinal gradient in the ichthyoplankton, associations with coastal and shelf-edge processes, and evidence of a spawning area in the sheltered KwaZulu-Natal Bight.

Melting of Fe-bearing and Fe-free carbonated pelites under fluid-saturated conditions at 6 GPa

Abstract Although the induced melting of pelitic sediments, i.e. the devolatilization of hydrous and carbonate minerals, has been widely studied at fluid-undersaturated conditions, the flush dissolution of carbonated pelite has not been fully understood yet. In addition, the role of iron in the melting of carbonated pelite has not received much attention. To address these issues, we conducted two sets of experiments for carbonated pelite with an iron-bearing (LH-gloss) and an iron-free (LHIF-gloss) starting bulk composition at 5.5-6 GPa, 800-1600°C at fluid-saturated conditions. The phase assemblages for both experiments at 800°C are composed of garnet + clinopyroxene + coesite + kyanite + phengite + aragonite + magnesite ± lawsonite ± rutile. Higher jadeite component and lower diopside-hedenbergite solid solution (Di-Hdss) in omphacitic clinopyroxene are observed in the LH-gloss experiment; also, garnet remains stable to higher temperatures (800-1400°C) in the LH-gloss than in the LHIF-gloss (900-1200°C). Carbonate- and phengite-out temperature boundaries are overlapping in the respective system, with the temperature boundary in the LH-gloss (800-900°C) slightly lower than that in the LHIF-gloss experiment (900-1000°C). The different stability fields of volatile-bearing minerals can be ascribed not only to variable bulk XH2O [H2O/(H2O + CO2)], which in turn, depends on bulk H2O, CO2 and K2O contents, but also to bulk FeO*(Total Fe as FeO) content. Both the characteristic “fish egg” texture and the strong increase of the amount of dissolved solids in the liquid phase over a narrow temperature interval at 6 GPa testify the possible existence of supercritical fluid. The marked solvent power of supercritical fluid can explain the earlier disappearance of experimental products including phengite, aragonite and magnesite. For the produced liquid phase (supercritical fluid or melt), the K2O/Na2O weight ratio decreases, whereas that of the SiO2/CaO increases with increasing temperature, placing potassium-rich carbonatitic supercritical fluids in the low-temperature and sodium-rich (carbonated) silicate melts in the high-temperature sections of both systems. The produced ultrapotassic (supercritical) liquid, when liberated from the subducting slab, may evolve into a melt parental to carbonatites and possibly result in the formation of diamonds. While those (carbonated) silicate melts, especially for the more oxidized and buoyant ones produced by the melting of ferrous iron-depleted carbonated pelite, are expected to intensely interact with the peridotite during the upward migration, which could lead to the formation of the metasomatic garnet pyroxenite.

Application of feed additives obtained from fish roe and glycerin in trout diet

These studies were carried out in the Rostov region on the replacement and broodstock of amber trout in the second and fourth stages of maturity. The purpose of the work: to study the effect of newly developed feed additives from pond fish milt and glycerin on the performance of salmon fish. As part of achieving this goal, it is necessary to solve the following tasks: to analyze various proportions of pond fish milt and glycerin; carry out feeding of salmon fish from the second to the fourth stage of maturity; study the growth rates of fish. According to the scheme of the experiment, the first (control) group of fish received complete feed without additives. In the complete feed for the second experimental group, 2% glycerol was included by weight of the feed. The diet for trout of the third group included pond fish milt with glycerol 50 to 50% in the amount of 2.0% by weight of the feed. In the second stage of maturity, a significant increase in gross growth in the second and third groups by 13.5% and 14.4% (P&lt;0.01) was found in relation to the control group. There was also a tendency to increase the length of the body in the experimental groups by 0.7 and 0.6 cm, respectively. The highest coefficient of fatness was in the group with 2% glycerol (6.97%). In the fourth stage of maturity, the trend towards a significant increase in gross growth continued. In the second experimental group, this indicator was higher than the control by 18.2% (P&lt;0.01) and by 17.1% (P&lt;0.01) in the third. The fatness coefficient in the control group was 1.74, in the second group it was significantly higher by 5.2% (P&lt;0.01).

Dietary omega-3 fatty acid does not improve male infertility caused by lysophospholipid acyltransferase 3 (LPLAT3/AGPAT3) deficiency

Docosahexaenoic acid (DHA), an omega-3 fatty acid, usually presents as a constituent of phospholipids in the cellular membrane. Lysophospholipid acyltransferase 3 (LPLAT3; AGPAT3) is the primary enzyme that incorporates DHA into phospholipids. LPLAT3-KO mice show male infertility and visual dysfunction accompanied by decreased phospholipids (PLs) containing DHA (PL-DHA) in the testis and retina, respectively. In this study, we evaluated the effect of diets consisting mainly of triacylglycerol-bound DHA (fish oil) and PL-bound DHA (salmon roe oil) on the amount of PL-DHA in a broad range of tissues and on reproductive functions. Both diets elevated phosphatidylcholines (PCs)-containing DHA in most tissues of wild type (WT) mice. Although LPLAT3-KO mice acquired a minimal amount of PC-DHA in the testes and sperm by eating either of the diets, reproductive function did not improve. The present study suggests that DHA-rich diets do not restore sufficient PL-DHA to improve male infertility in LPLAT3-KO mice. Alternatively, PL-DHA can be biosynthesized by LPLAT3 but not by external supplementation, which may be necessary for normal reproductive function.