Triploid brown trout, Salmo trutta, develop functional gonads with age and are able to interbreed with diploid counterparts.

The study investigated if gonad maturation in triploid brown trout, Salmo trutta, was entirely suppressed or only delayed, and if triploids could interbreed with diploid counterparts. Ten percent of the total number of 3-year-old triploid S. trutta, 15% of 4-year-old fish, and 17% of 5-year-old fish produced semen. Three and 4 years old triploid fish did not produce eggs, but 15% of the 5-year-old fish did so. The quantity and sperm motility of triploid semen did not differ from diploids, but the sperm concentration was significantly lower. When diploid eggs were fertilized with triploid semen (3n × 2n crosses), the percentage of eyed stage embryos, of hatched larvae, and of normal-shaped larvae did not differ from the diploid controls. Circa 90% of 3n × 2n crosses had a ploidy level of 2.4n. In the remaining percentage of 3n × 2n crosses, the ploidy level was ≥2n and <2.4n. In sperm competition experiments where diploid eggs were fertilized with a mixture of diploid and triploid semen, 52% of the originating larvae had a ploidy level of 2n, 43% of 2.4n, and 5% of the fish were not exactly classified. From the start of feeding to an age of 248 days, the mortality rate of 3n × 2n interploid crosses and of 2n × 2n controls was similar. The growth of interploid crosses was significantly higher than that of controls. In triploid mature females, the egg mass per kilogram of body weight was significantly lower than in diploids. The mass of the non-hardened eggs and the percentile weight increase during hardening did not differ from diploid eggs. When triploid eggs were fertilized with diploid semen (2n × 3n crosses), the development rate to normal hatched larvae was less than 10%. All originating larvae had a ploidy level of 3n. From the start of feeding to an age of 248 days, 2n × 3n crosses had a higher mortality rate (15%) than diploid controls (<5%). Growth of this type of interploid crosses was reduced in comparison to controls. Therefore, triploids introduced into natural waters for recreational fisheries or escaping from farms may interbreed with diploid counterparts. This not only alters the genotypes of local populations but also changes the ploidy levels.

Occurrence and pattern of legacy and emerging per- and Poly-FluoroAlkyl substances (PFAS) in eggs of loggerhead turtle Caretta caretta from western Mediterranean.

Per-and Poly-FluoroAlkyl Substances (PFAS) are a class of persistent, toxic, and mobile and chemicals both from industrial sources and from the use and disposal of Consumers products containing PFAS, whose concentration in marine food webs could pose a toxicological risk for biota and humans. In 2021, unhatched eggs were sampled from 41 loggerhead turtle Caretta caretta nests from the Italian shores of the Campania Region (Southern Italy). Whole eggs were analysed for the presence of 66 legacy and emerging PFAS with Liquid Chromatography coupled to Hybrid High Resolution Mass Spectrometry. A median Σ66 Per- and Poly-FluoroAlkyl Substances value of 3.34 ng/g egg fresh weight was found; perfluoroctane sulfonate (PFOS) represented the most contributing congener (47%), followed by perfluoro-n-undecanoic acid, perfluoro-n-tridecanoic acid, perfluoro-n-decanoic acid, perfluoro-n-decanoic acid, and perfluoro-n-tetradecanoic acid, respectively. Such compounds showed a log-norm distribution, suggesting found concentrations could represent the baseline levels in the considered sampling area. Emerging ChloroPolyFluoroPolyEthers Carboxylic Acids (ClPFECAs) were found in 20 out of 41 samples in the range 0.01-1.59 ng/g. Four samples had 20-100 fold higher concentration compared to that of other samples, suggesting the presence of hot spot areas possibly related to presence of fluoropolymer-based marine litter turtles may ingest. The analysis of two paired eggs/liver samples recovered from stranded animals revealed PFAS concentration in the same order of magnitude, supporting the role of vitellogenin in their selective transfer to yolk. Significant (P = 0.0155) Kendall negative correlation coefficient of -0.2705 among PFOS content in eggs and the recorded hatching success prompts for further investigation on associated exposure assessment and related eco-toxicity risk. This work reports for the first time PFAS presence in georeferenced loggerhead turtle eggs of the Mediterranean Sea and results represent a starting point to study PFAS time-trends in this vulnerable species.

Anidación de la tortuga marina Lepidochelys olivacea (Testudinata: Cheloniidae) en Campamento Tortuguero Cedeño, Honduras (2011-2021) / Nesting of olive ridley sea turtle Lepidochelys olivacea (Testudinata: Cheloniidae) in Campamento Tortuguero Cedeño, Honduras (2011-2021)

Introducción: El Campamento Tortuguero de Cedeño ha sido el sitio menos investigado del Golfo de Fonseca, donde se protege a la tortuga golfina en Honduras desde 1975. Objetivo: Evaluar la anidación de la tortuga Golfina (Lepidochelys olivacea) durante la temporada de veda entre el 2011 y 2021 en Campamento Tortuguero Cedeño, Choluteca, Honduras. Métodos: Entre 2011 a 2021, se llevó a cabo el monitoreo diario de las actividades de anidación durante la veda del 1 al 25 de septiembre. Los patrullajes se realizaron entre las 6:00-18:00 h, y las 18:00-5:00 h. Se registró el número total de tortugas que anidaban y se recogieron sus huevos, que se transportaron al criadero, donde se tabularon los resultados de las puestas y las crías. Resultados: Se registró un total 1 065 tortugas de L. olivacea, 95 051 huevos recolectados, 1 065 nidos marcados en tres playas que fueron reubicados en viveros artificiales y una eclosión exitosa de 62 747 neonatos. La playa Las Doradas fue el sitio con el mayor número de tortugas anidadoras, seguido de Los Delgaditos y por último Cedeño. El promedio de la frecuencia de anidación fue de 96 nidos. Del 2011 al 2021 el esfuerzo de recolección de los nidos aumentó en un 91.6 %, pasando de 84 a 161 nidos. El número de personas patrullando se asoció con la cantidad de nidos detectados en las playas. Conclusión: Los esfuerzos de monitoreo y conservación para la especie han indicado que ha habido un incremento en la anidación de L. olivacea en las tres playas, con un mayor incremento en Playa Las Doradas. Este escenario comprueba la funcionalidad de la veda en esta zona.

Introduction: The Cedeño Turtle Camp has been the least researched site in the Fonseca Gulf, where Olive Ridley Turtles in Honduras have been protected since 1975. Objective: To evaluate the nesting of Olive Ridley turtles (Lepidochelys olivacea) during the closed season from 2011 to 2021 in Campamento Tortuguero Cedeño, Choluteca, Honduras. Methods: From 2011 to 2021, daily monitoring of nesting activities was conducted during the closed season from the 1st to 25th of September. Patrols were conducted between 6:00-18:00 h, and 18:00-5:00 h. The total number of nesting turtles was recorded, and their eggs were collected and transported to the hatchery, where clutch and hatchling performance were tabulated. Results: A total of 1 065 L. olivacea turtles were recorded, 95 051 eggs collected, 1 065 nests marked on three beaches that were relocated in artificial hatcheries and a successful hatching of 62 747 hatchlings. Las Doradas beach was the site with the highest number of nesting turtles, followed by Los Delgaditos and lastly Cedeño. The average nesting frequency was 96 nests. From 2011 to 2021 the nest collection effort increased by 91.6 %, from 84 to 161 nests. The number of people patrolling was associated with the number of nests detected on the beaches. Conclusion: Monitoring and conservation efforts for L. olivacea in the Campamento Tortuguero Cedeño show a positive trend in nesting with a greater increase in Playa Las Doradas. This scenario proves the functionality of the closed season in this area.

Broodstock development, induced spawning and larval rearing of the bilih, Mystacoleucus padangensis (Bleeker, 1852), a vulnerable species, and its potential as a new aquaculture candidate.

Background: Mystacoleucus padangensis living in Lake Singkarak, Indonesia, has high potential market demand but is threatened by overfishing and has not been successfully cultured. This study describes the first broodstock development, induced breeding, and larval rearing of M. padangensis. Methods: A total of 1,000 female and 1,000 male broodfish were collected from the wild and reared in two concrete ponds (128 m 2) at the Centre for Biodiversity Conservation, P.T. Semen Padang, Indonesia. The broodfish were fed commercial feed to satiation at 09:00 and 17:00 h. The females (average weight 7.56 ± 0.85 g) and males (4.86 ± 1.20 g) were selected at a ratio of 1:4 (female:male), and gonad maturation was induced with a single dose of GnRH analogue (Ovaprim) of 0.1 ml/fish. At 16 h after hormone injection, eggs were collected individually into a plastic vessel. Spermatozoa were collected with sterile syringes. Eggs were fertilized using the "dry" method, and 0.5 ml samples (equal to 100 eggs) were taken. The eggs were incubated in a plastic strainer with a water volume of 1.57 litres and placed in a tarpaulin pond with a volume of 150.72 litres. Results: The overall hatching rate was 78.93 ± 4.13%. The newly hatched larvae were 3900.81 µm long, with a yolk sac of 82881.480 µm 2. The mouth opened at 72 days post hatching (DPH) with a gape measuring approximately 61.880 µm. The protocol of larval feeding started with artificial feed, followed by Artemia nauplii up to 30 DPH. Weaning of larvae started at 4 DPH. Larvae started metamorphosis by 15 DPH and ended by 22 DPH when the larvae reached 7430.27 µm. Larval rearing resulted in an average survival rate of 28.4 ± 3.04%. Conclusions: Its successful spawning induction and high larval hatching and survival rates make M. padangensis an excellent aquaculture candidate.

Hierarchical shift of the Aedes albopictus microbiota caused by antimicrobiota vaccine increases fecundity and egg-hatching rate in female mosquitoes.

Recent studies show that mosquito-microbiota interactions affects vector competence and fitness. We investigated if host antibodies modifying microbiota impact mosquito physiology. We focused on three prevalent bacteria (Acinetobacter, Pantoea, and Chryseobacterium), originally isolated from the Asian tiger mosquito Aedes albopictus. Our goal was to assess the impact of host antibodies on mosquito microbiota and life traits. Female mosquitoes were fed with blood from rabbits immunized with each bacterium or a mock vaccine. We compared various factors, including feeding behavior, survival rates, and reproductive success of the mosquitoes. Interestingly, mosquitoes fed with blood from a Chryseobacterium-immunized rabbit showed a significant increase in fecundity and egg-hatching rate. This outcome correlated with a decrease in the abundance of Chryseobacterium within the mosquito microbiota. While no significant changes were observed in the alpha and beta diversity indexes between the groups, our network analyses revealed an important finding. The antimicrobiota vaccines had a considerable impact on the bacterial community assembly. They reduced network robustness, and altered the hierarchical organization of nodes in the networks. Our findings provide the basis for the rational design of antimicrobiota vaccines to reduce mosquito fitness and potentially induce infection-refractory states in the microbiota to block pathogen transmission.

The investigation of post-thaw chilled storage and the applicability of large-scale cryopreservation in chub (Squalius cephalus) sperm.

Chub (reophillic cyprinids) is one of the most sensitive bioindicator fish of environmental changes following anthropogenic activities. The improvement of different biotechnological procedures could help support its conservation and strengthen the natural populations. The aim of this study was to compare the effects of two different hormonal agents (carp pituitary extract and Ovopel™) on various motility parameters (pMOT-%, DAP-µm, VCL µm s-1, VSL-µm s-1, LIN-%, ALH-µm, BCF-Hz) of fresh and cryopreserved/thawed sperm (stored at 4 °C for 6 h). Additionally, we sought to develop a novel, large-scale cryopreservation method for chub sperm, assessing freezing methods (Styrofoam box and a controlled-rate freezer) and different containers (0.5, 5 mL straw and 4 mL cryotube) for sperm cryopreservation. The results of this study indicated no difference between the carp pituitary extract and Ovopel treated groups in either the fresh or frozen/thawed sperm (at 0, 3, 6, hour post thawing, P = 0.4351). In contrast, the quality of the thawed chub sperm was negatively affected after 3 h chilled storage in both hormonal treatments (P = 0.0036, P < 0.0001). When assessing the motility parameters of the sperm between the 5 mL straw and 4 mL cryotube groups cryopreserved in a Styrofoam Box, no difference was observed (P = 0.103). Additionally, sperm loaded in 4 mL cryotubes showed no difference in motility when cryopreserved with either the Styrofoam box or controlled-rate freezer methods (P = 0.109). A similar hatching rate was observed in sperm preserved using the Styrofoam box (35 ± 7 %) and controlled rate freezer (25 ± 9 %) methods (P = 0.300). In a second fertilization trial, hatching rate was similar between control (72 ± 19 %) and cryopreserved (4 mL cryotube and Styrofoam box, 61 ± 5 %) groups. (P = 0.257). Based on our findings and its standard features (less species specific, precise dose calculation), Ovopel can be a good candidate for the stimulation of spermiation in chub sperm prior to cryopreservation. Furthermore, our study presents a novel and applicable method for the large-scale cryopreservation of chub sperm.

Carotenoids and retinoids in the gonad of brood-stock pikeperch: accumulation during vitellogenesis and influence on egg quality in farmed pikeperch Sander lucioperca.

Carotenoids are determinants of reproductive fitness and egg quality. Here we studied the accumulation of astaxanthin (AX), canthaxanthin (CA) zeaxanthin (ZX), lutein (LU), retinol (RX) and dehydroretinol (DR) during vitellogenesis comparing previtellogenic and vitellogenic pikeperch (Sander lucioperca) eggs (n = 5 each), as well as selected tissues (liver, fat and muscles) in first süawning females (1176-1450 g). Futhermore, we compared egg batches with high (88-99% hatching rate, n = 5) or low (40-67% hatching rate, n= 5) egg quality. Vitellogenic follicles revealed higher concentrations of DR, RX, ZX and LU compared to previtellogenic follicles. Neither CA nor AX was detectable. In parallel, DR and RX were mobilized in the liver. In adipose and muscle tissue, comparing previtellogenic and vitellogenic females, no significant differences in carotenoid/retinoid content were observed. In high quality egg batches, both DR and RX were increased. LU was lower in high quality than in low quality eggs. In a conclusion, the amount of retinoids seems suboptimal in low quality egg batches and increased DR and RX are desirable in pikeperch. Since hypervitaminosis of retinoids can be problematic though, supplementation of the food with carotenoids, which can serve as precursors for retinoids, has to be carried out carefully.

Expression and functional analysis of transformer-2 in Phytoseiulus persimilis and other genes potentially participating in reproductive regulation.

Transformer-2 (tra-2) is an important sex-determining gene in insects. It also plays a role in the reproduction of phytoseiid mites. We performed bioinformatic analyses for the tra-2 ortholog in Phytoseiulus persimilis (termed Pptra-2), measured its expression at different stages and quantitatively identified its function in reproduction. This gene encodes 288 amino acids with a conserved RRM domain. The peak of its expression was observed in adult females, especially ca. 5 days after mating. In addition, expression is also higher in eggs than in other stages and adult males. When Pptra-2 was silenced through RNA interference with oral delivery of dsRNA, 56% of the females had their egg hatching rates decreased in the first 5 days, from ca. 100% to ca. 20%, and maintained at low levels during the rest of the oviposition period. To detect other genes functionally related to Pptra-2, transcriptome analyses were performed on day 5 after mating. We compared mRNA expressions among interfered females with significantly reduced egg hatching rate, interfered females without significant hatching rate and CK. In total 403 differential genes were identified, of which 42 functional genes involved in the regulation of female reproduction and embryonic development were screened and discussed.

Effects of Eggshell Thickness, Calcium Content, and Number of Pores in Erosion Craters on Hatching Rate of Chinese Alligator Eggs.

The Chinese alligator (Alligator sinensis), found only in a small region in southeastern Anhui Province, is listed as critically endangered (CR) by the International Union for Conservation of Nature (IUCN) due to its current declining population trend. Any abnormalities in the physical properties of an egg can decrease the hatching rate. In particular, eggshells play an essential role in embryo development, motivating us to analyze the microstructures of the eggshells of Chinese alligators. In this study, we categorized the eggshells into two groups, based on the hatching rates, and analyzed the relationship between the eggshell parameters (eggshell thickness, calcium content, and number of pores in erosion craters) and the hatching rate, as well as the relationships between the eggshell parameters. We found that the shells of the eggs with high hatching rates were thicker than those of the eggs with low hatching rates. There were also fewer erosion-crater pores on the surfaces of the eggs with high hatching rates than on the surfaces of the eggs with low hatching rates. Moreover, the shell Ca content was significantly higher in the eggs with high hatching rates than in the eggs with low hatching rates. Cluster modeling indicated that the highest hatching rate occurred when the eggshell thickness was 200-380 µm and there were 1-12 pores. These results suggest that eggs with adequate Ca contents, thicker shells, and less air permeability are more likely to hatch. Furthermore, our findings can inform future studies, which will be vital for the survival of the critically endangered Chinese alligator species.

Hydroxyapatite-binding Silver/Titanium Dioxide as a Potential Control Compound Against Mosquito Vectors, Aedes aegypti (Diptera: Culicidae) and Anopheles dirus (Diptera: Culicidae).

Controlling mosquitoes is vital for counteracting the rising number of mosquito-borne illnesses. Vector control requires the implementation of various measures; however, current methods lack complete effectiveness, and new control agents or substances are urgently needed. Therefore, this study developed a nonwoven fabric sheet coated with hydroxyapatite-binding silver/titanium dioxide compound (hydroxyapatite-binding silver/titanium dioxide sheet [HATS])and evaluated its effectiveness on all stages of laboratory Aedes aegypti (Linnaeus); Diptera: Culicidae and Anopheles dirus (Peyton & Harrison); Diptera: Culicidae. We reared larvae with HATS and control sheets and assessed their mortality, emergence, and hatching rates. The submersion rates of engorged female mosquitoes in submerged HATS and control sheets were also compared. The HATS strongly affected mosquito development, resulting in high mortality rates (mean ± SE) of 99.66 ± 0.58% (L1-L2) and 91.11 ± 9.20% (L3-L4) for Ae. aegypti and 100% of both stages for An. dirus. In contrast, mosquitoes raised in the control sheet showed relatively high survival rates of 92.33 ± 3.21% (L1-L2) and 95.67 ± 0.58% (L3-L4) for Ae. aegypti and 86.07 ± 3.53% (L1-L2) and 92.01 ± 8.67% (L3-L4) for An. dirus. Submersion of engorged females was found in the HATS oviposition cup, leading to a decreased number of eggs and a low hatching rate compared to that of the control. Overall, HATS may be a useful new control method for Ae. aegypti and An. dirus.

Cytotoxicity of lycopene-mediated silver nanoparticles in the embryonic development of zebrafish-An animal study.

Nano-silver (AgNP) has biological properties which are significant for consumer products, food technology, and medical applications (e.g., wound care products, implantable medical devices, in diagnosis, drug delivery, and imaging). Thus, the use of nano-silver is becoming more and more widespread in medicine. However, the effect of these AgNPs on zebrafish remains unclear. Whereas, lycopene, a fat-soluble carotenoid acts as a potent antioxidant has proved its major role in treating many oral health problems such as lichen planus, and periodontitis. Usage of these lycopene AgNPs would yield better results in wound healing. In this study, we investigated the cytotoxic effects of AgNPs on fibroblasts cells of humans. To investigate the toxic effects of the lycopene-mediated AgNPs on the zebrafish (Danio rerio) and to examine these effects on the embryonic development of the fetus of this species. In this study, zebrafish embryos were treated with AgNPs 0.5, 1, 2, 3, 4 or 5 L nanoparticles/ml for 24 to 96 h post fertilization. Our results showed that with the increasing concentration of nanoparticles, there was a very mild toxic effect. Less toxic effects were observed with 1µl. Our results show that exposure to silver nanoparticles is less toxic to embryonic zebrafish at lower concentrations. The results will contribute to the current understanding of the potential biotoxic effects of nanoparticles and will aid in the safety assessment and synthesis of silver oxide nanoparticles.

Temperature, season, and latitude influence development-related phenotypes of Philippine Aedes aegypti (Linnaeus): Implications for dengue control amidst global warming.

BACKGROUND: Dengue is endemic in the Philippines. Aedes aegypti is the primary vector. This study aimed to determine the hatching behavior and viability of Ae. aegypti first-generation (F1) eggs when exposed to temperature and photoperiod regimes under laboratory conditions. METHODS: Parental eggs were collected from selected highland and lowland sites in the Philippine big islands (Luzon, Visayas, and Mindanao) during the wet (2017-2018) and dry (2018) seasons. F1 egg cohorts were exposed separately in environmental chambers at 18, 25, and 38 °C with respective photoperiods for 6 weeks. Phenotypes (percent pharate larvae [PPL], hatch rates [HRs], and reproductive outputs [ROs]) were determined. RESULTS: Results of multivariate analyses of variance (MANOVA) between seasons showed significant main effects of temperature, season, and big island on all phenotypes across all sites. Significant interaction effects between seasons on all phenotypes across sites were shown between or among (1) season and big island, (2) season and temperature, (3) big island and temperature, (4) season, big island, and temperature, (5) big island, altitude, and temperature, and (6) season, big island, altitude, and temperature. Factors associated with the big islands might include their ecology, available breeding sites, and day lengths due to latitudinal differences, although they were not measured in the field. MANOVA results within each season on all phenotypes across sites showed (1) significant main effects of big island and temperature, and (2) significant interaction effects between big island and temperature within the wet season and (3) between temperature and photoperiod within the dry season. PPL were highest at 18 °C and were formed even at 38 °C in both seasons. Pharate larvae might play an adaptive role in global warming, expanded distribution to highlands, and preponderance to transmit human diseases. HRs in both seasons were highest at 25 °C and lowest at 38 °C. ROs were highest at 25 °C in the wet season and at 18 °C in the dry season. CONCLUSIONS: Temperature and latitude of Philippine big islands influenced the development-related phenotypes of Ae. aegypti in both seasons. The two seasons influenced the phenotypes and their interaction effects with big island and/or temperature and/or altitude. Recommendations include year-round enhanced 4S control strategies for mosquito vectors and water pipeline installation in rural highlands.

Reproduction of Black Soldier Fly (Diptera: Stratiomyidae) Under Different Adult Densities and Light Regimes.

The black soldier fly (BSF) Hermetia illucens (L.) (Diptera: Stratiomyidae) has been recognized as a promising insect species for sustainable management of organic waste and by-products. Indoor breeding of BSF with artificial lighting has been proved successful, but efforts are still needed to optimize BSF reproductive output. Increasing adult density seems an option to exploit space, whereas decreasing artificial lighting duration may reduce unnecessary power consumption. This study aimed at investigating the effects of adult density (10, 25, and 50 pairs per 30 × 30 × 30 cm cage; i.e., 370, 926, and 1,852 pairs/m3), light regime (8:16, 12:12, and 16:8 [L:D] h), and their possible interactions, on some BSF life history traits relevant to reproduction. The results show that the overall BSF reproductive output increased with increasing adult density but was not affected by light regimes per se. With the highest BSF adult density tested, an average of more than 20,000 neonate larvae were produced from a cage within 10 d. At this density, increasing photoperiod increased neonate production, but also decreased the number of neonates per watt used for artificial illumination. The temporal oviposition patterns, mean individual female reproductive output, mating success, egg hatching rate, and insect survival rate were not affected by adult density or light regime as simple effects. However, the interaction between adult density and light regime was significant for the first oviposition peak, mean individual female reproductive output, and insect survival rate. The possible mechanisms behind our results are discussed.

Reproduction of Limnatis paluda (Tennent 1859) in laboratory conditions.

The reproductive functions of Limnatis paluda were studied in laboratory conditions including imposing of two thermal conditions (T1: 18 ± 2 °C and T2: 26 ± 2 °C) and with there being placement of three bedding substrates (tile, moss, and stone) in the containers specimens were confined. Furthermore, values for reproductive variables of cocoons and hatchlings were recorded. With the T2 treatment, gravid adults had cocoon depositions, whereas those when there was imposing of the T1 treatment did not have cocoon depositions. There was cocoon deposition only on the moss bedding, and it is presumed that moss could provide a robust and stable nursing microenvironment for developing embryos. Frequency (%) of cocoon depositions did not vary during the months of the deposition period. Hatching occurred after 26 ± 2 days when there was imposing of the T2 treatment. There was no correlation between the values for size of the ovigerous cocoons and number of offspring. There was a negative correlation between number and mean weight of hatchlings. There was a difference in cocoon weight for the different months and fluctuation in mortality and hatching rate which is assumed to be related to differences in feeding behaviors.

Preliminary Observations of the Effect of Temperature and Food Concentration on the Egg Production Rate and Hatching Success of Acartia amboinensis from the Central Red Sea.

The effects of temperature and food concentration on the egg production rate (EPR) of the tropical calanoid copepod Acartia amboinensis were studied from the coastal waters of the central Red Sea in March 2017. In the first experiment, adult females were incubated in glass bottles that were pre-filled with screened seawater containing a natural assemblage of phytoplankton. In the second experiment, the species were incubated in glass bottles that were enriched with different concentrations of Chaetoceros muelleri along with natural assemblages of phytoplankton. Both the experimental setups were then exposed to different temperatures (21, 24, 27, 30 and 33°C). The daily EPR varied significantly across different temperatures and the various food concentrations (p < 0.05). Within the natural food assemblage (Exp. 1), the EPR increased gradually to a peak mean of 13.7 eggs female-1 d-1 at 27°C, then declined as temperatures increased (at 30 and 33°C). In the second experiment when the water was enriched with algal culture, EPRs were significantly greater (maximum EPR: 63.9 eggs female-1 d-1 at 27°C) than those incubated in ambient water with natural food (maximum EPR: 17.4 eggs female-1 d-1 at 21°C). The hatching rate fluctuated between 42.4% and 88.6%. The present study revealed that the EPR of Acartia amboinensis responded rapidly to changes in food availability, suggesting an extreme food limitation in the central Red Sea.

Comparison of responses to artificial spawning of ruffe (Gymnocephalus cernua) specimens captured from their natural habitat to those produced in cultured conditions.

Although ruffe (Gymnocephalus cernua) are widely distributed in Eurasia, in some regions (i.e., North America) ruffe are considered an invasive species. There have been no reports on artificial reproduction of this species. A study, therefore, was conducted to evaluate reproduction of ruffe with results of specimens captured from their natural habitat and cultured (F1 generation) specimens being compared. Spawning specimens from both stocks were treated with hormonal preparations: carp pituitary homogenate (CPH), Ovopel, Ovaprim and human chorionic gonadotropin (hCG) and results were analyzed by comparing response to the specimens of control groups. Spermiation outcomes and sperm motility of the captured and cultured ruffe were similar and with all hormonal treatments, there was a slightly greater sperm motility (55.6 %-57.1 %) in comparison to specimens of control groups (46.7 %-47.1 %). For captured specimens, there was no asynchronous development of oocytes, whereas in cultured specimens 32 % of females had asynchronous development of oocytes. The ovulation rate in specimens of all treated groups was 100 %, whereas specimens in the control groups did not reproductively mature and have ovulations. The latency time from time of hormonal treatments to initiation of reproductive functions depended on the spawning agent used and oocyte maturation stage and there was the shortest latency after using CPH and the longest with hCG treatment. The embryo survival and hatching rates varied with use of different hormonal preparations to induce reproduction: greatest hatching rates with hCG treatment (86.4 %-88.9 %), followed by Ovaprim (78.2 %-80.2 %) and least hatching rate with Ovopel and CPH treatments (66.0 %-67.1 % and 64.0 %-66.0 %, respectively).

Validation of the Turkey Semen Cryopreservation by Evaluating the Effect of Two Diluents and the Inseminating Doses.

This study was designed to test the fertilizing ability of cryopreserved turkey semen, and here, two experiments were performed: an in vitro analysis to assess the effects of Tselutin and Lake diluents and an in vivo test to determine the fertility and hatching rates by also studying the feat of three insemination doses (250, 400 and 600 × 106 sperm/hen). Pooled semen samples were diluted with Tselutin or Lake extender which contained 20% of dimethylsulfoxide and 1 mM of Ficoll at final sperm concentration of 3 × 109 sperm/mL. Thereafter, semen was packaged into straws and frozen on liquid nitrogen. The post-thaw sperm quality was evaluated considering motility (computer-aided sperm analysis-CASA system) and membrane integrity (flow cytometry). Significantly higher values of progressive motility and some kinetic parameters in semen frozen with Lake were found. When we compared the extenders in vivo, no significant effects were detected, whilst sperm concentration significantly affected both fertility and hatching rates, with the best results obtained with the sperm concentration of 400 × 106 sperm/hen. From the results obtained, it emerged that the extender type only affected sperm motility characteristics, not the fertilizing ability of frozen-thawed semen, while inseminating dose markedly affected fertility and hatching rates.

Comparison of artificial spawning effectiveness of hCG, CPH and GnRHa in combination with dopamine inhibitors in a wild strain of ide Leuciscus idus (L.) in hatchery conditions.

Optimization of artificial reproduction, by increasing the survival rate of embryos and hatching rate, is of major importance for reducing genetic diversity, especially in fish captured from their natural habitat that subsequently spawn in hatcheries. The artificial reproduction of ide, Leuciscus idus (L.) was conducted in controlled conditions. The spawning agents included: different doses of human chorionic gonadotropin (hCG) that was compared with common carp pituitary homogenate (CPH), Ovopel - a commercial agent for induction of spawning that contains mammalian gonadotropin releasing hormone analogue (mGnRHa) with dopamine antagonists (DA): metoclopramide (MET) and Ovaprim - a commercial agent containing salmon gonadotropin releasing hormone analogue (sGnRHa) and a dopamine antagonists (DA): domperidone (DOM). There were no ovulations in females from control groups. There were no differences between the ovulation rates (90 %) or embryo survival (> 92 %) and hatching rates (> 91 %) when there was administration of hCG doses between 500 and 1000 IU/kg. When there was comparison of different spawning agents, the ovulation rate was 100 % for all treated groups. There were the shortest and longest latency times to the time of ovulation after administration of CPH (26 h) and hCG (79 h), respectively. The greatest embryo survival (> 93 %) and hatching (> 91 %) rates occurred as a result of hCG administration with these values being slightly greater than when there was treatment with Ovaprim. The association between latency time and hatching rate indicated that when there was a slower final oocyte maturation (FOM) there were greater hatching rates.

Microplastics negatively impact embryogenesis and modulate the immune response of the marine medaka Oryzias melastigma.

Microplastic (MP) pollution is an emerging contaminant in aquatic environments worldwide. Nonetheless, the developmental toxicity of MPs in the early life stages of fish and the mechanisms involved are not yet fully understood. The present study investigated the effects of different concentrations of polystyrene (PS) MPs on the early development of the marine model fish the medaka Oryzias melastigma. Our results showed that waterborne exposure to PS MPs significantly delayed the hatching time, altered the heartbeat and decreased the hatching rate of embryos. Furthermore, the genes involved in cardiac development, encoding for embryo-hatching enzymes, as well as inflammatory responses were significantly upregulated. The transcriptome results showed that mainly the pathways involved in metabolism, immune response, genetic information processing and diseases were significantly enriched. These results demonstrate that PS MPs negatively impact embryogenesis and the immune response of O. melastigma.

Toxicity of palm oil mill effluent on the early life stages of Nile tilapia (Oreochromis niloticus, Linnaeus 1758).

Harmful effects of several pollutants have been reported on early life stages of fish. However, the effects of palm oil mill effluent (POME) on fish early life stages are still unexplored. Therefore, the objective of this present study was to elucidate the impact of POME on the early life stages of Nile tilapia (Oreochromis niloticus). Fertilized eggs of Nile tilapia were exposed to four concentrations of POME (0, 1.565, 2.347, and 3.130 mg/L) in 20 plastic funnels. Each of the control and treatment groups was maintained in five replicates. The cumulative hatching rate, malformation rate, body length, and deformities of larvae were analyzed. Results showed that hatching rate and survival rate of Nile tilapia larvae significantly decreased with increasing concentrations of POME. In contrast to, malformation rate and heart rate were significantly increased. Furthermore, results showed several malformations of Nile tilapia larvae including lordosis, kyphosis, and curved tail when exposed to 1.565 mg/L, 2.347 mg/L, and 3.130 mg/L of POME concentrations. Further research is required to understand the physiological mechanisms of different endpoints in the early stages of Nile tilapia induced by the toxicity of POME.