Anthropogenic noise disrupts early-life development in a fish with paternal care

Anthropogenic noise is a global pollutant but its potential impacts on early life-stages in fishes are largely unknown. Here, using controlled laboratory experiments, we tested for impacts of continuous or intermittent exposure to low-frequency broadband noise on early life-stages of the common goby (Pomatoschistus microps), a marine fish with exclusive paternal care. Neither continuous nor intermittent noise exposure had an effect on filial cannibalism, showing that males were capable and willing to care for their broods. However, broods reared in continuous noise covered a smaller area and contained fewer eggs than control broods. Moreover, although developmental rate was the same in all treatments, larvae reared by males in continuous noise had, on average, a smaller yolk sac at hatching than those reared in the intermittent noise and control treatments, while larvae body length did not differ. Thus, it appears that the increased consumption of the yolk sac reserve was not utilised for increased growth. This suggests that exposure to noise in early life-stages affects fitness-related traits of surviving offspring, given the crucial importance of the yolk sac reserve during the early life of pelagic larvae. More broadly, our findings highlight the wide-ranging impacts of anthropogenic noise on aquatic wildlife living in an increasingly noisy world.

Effect of summer temperature on prolonged diapause of Tettigoniidae (Orthoptera) under realistic field conditions

To face recurrent temperature changes, tettigoniids inhabiting temperate climates overwinter as eggs in a diapause stage, being able to postpone embryogenesis for one or more years. To date, it is unclear if species living in warm regions, especially under the Mediterranean climate, could exhibit a diapause for a single year or enter a prolonged diapause due to higher summer temperatures experienced by eggs immediately after oviposition. In this two-year study, we tested the effect of summer temperatures on diapause of six Mediterranean tettigoniid species under natural field conditions. We found that five species can exhibit a facultative diapause depending on mean summer temperatures. For two species, a substantial shift in egg development from 50 to 90% occurred over an interval of c. 1 °C after the first summer period. All the species increased considerably their development (nearly 90%) after the second summer period irrespective of temperatures. Overall, this study suggests that diapause strategy and the different thermal sensibility of embryonic development varies considerably across species potentially affecting their population dynamics.

Insight into the mechanism of action of scoparone inhibiting egg development of Tetranychus cinnabarinus Boisduval

Investigating the mechanisms of action of natural bioactive products against pests is a vital strategy to develop novel promising biopesticides. Scoparone, isolated from Artemisia capillaris, exhibited potent oviposition inhibition activity against Tetranychus cinnabarinus (a crop-threatening mite pests with strong fecundity). To explore the underlying mechanism, the vitellogenin (Vg) protein content, and Vg gene expression of mites from three consecutive generations of G0 individuals exposed to scoparone were determined, revealing marked inhibition. This study is the first to explore the egg development defect behaviour of mite pests induced by scoparone. The egg-laying inhibition of mites by scoparone was significantly increased by 47.43% compared with that of the control when TcVg was silenced by RNA interference (RNAi), suggesting that egg-development inhibition of female T. cinnabarinus by scoparone was mediated by low Vg gene expression. Furthermore, scoparone bound to the Vg protein in vitro, and its K_d value was 218.9 μM, implying its potential function in inhibiting the egg development of mites by directly targeting the Vg protein. This study will lay the foundation for the future applications of scoparone as an agrochemical for controlling the strong egg-laying capacity mite pests in agriculture.

RNA-Seq analysis of blood meal induced gene-expression changes in Aedes aegypti ovaries

Background

Transmission of pathogens by vector mosquitoes is intrinsically linked with mosquito’s reproductive strategy because anautogenous mosquitoes require vertebrate blood to develop a batch of eggs. Each cycle of egg maturation is tightly linked with the intake of a fresh blood meal for most species. Mosquitoes that acquire pathogens during the first blood feeding can transmit the pathogens to susceptible hosts during subsequent blood feeding and also vertically to the next generation via infected eggs. Large-scale gene-expression changes occur following each blood meal in various tissues, including ovaries. Here we analyzed mosquito ovary transcriptome following a blood meal at three different time points to investigate blood-meal induced changes in gene expression in mosquito ovaries.

Results

We collected ovaries from Aedes aegypti that received a sugar meal or a blood meal on days 3, 10 and 20 post blood meal for transcriptome analysis. Over 4000 genes responded differentially following ingestion of a blood meal on day 3, and 660 and 780 genes on days 10 and 20, respectively. Proteins encoded by differentially expressed genes (DEGs) on day 3 include odorant binding proteins (OBPs), defense-specific proteins, and cytochrome P450 detoxification enzymes. In addition, we identified 580 long non-coding RNAs that are differentially expressed at three time points. Gene ontology analysis indicated that genes involved in peptidase activity, oxidoreductase activity, extracellular space, and hydrolase activity, among others were enriched on day 3. Although most of the DEGs returned to the nonsignificant level compared to the sugar-fed mosquito ovaries following oviposition on days 10 and 20, there remained differences in the gene expression pattern in sugar-fed and blood-fed mosquitoes.

Conclusions

Enrichment of OBPs following blood meal ingestion suggests that these genes may have other functions besides being part of the olfactory system. The enrichment of immune-specific genes and cytochrome P450 genes indicates that ovaries become well prepared to protect their germ line from any pathogens that may accompany the blood meal or from environmental contamination during oviposition, and to deal with the detrimental effects of toxic metabolites.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-021-07551-z.

Early Life History of Lefua costata (Cypriniformes : Balitoridae) from Korea

The purpose of this study is to observe the early life history of Korean Lefua costata and use the result as basic taxonomic research data for balitorid fish. The fertilized eggs were light green color with completely circle shape and mean size was 1.21±0.06 mm (n=30). Immediately after hatching, the size of the larvae was 2.81±0.11 mm (n=5) in mean length, with egg yolk. On the 3rd day after hatching, the preflexion larvae had a mean length of 4.64±0.09 mm (n=5), and their mouth was opened to start feeding. On the 8th day after hatching, a mean length of the postflexion larvae was 9.43±0.46 mm (n=5), the distal part of the notochord was bent to 45°, and 16 fin rays were developed on the caudal fin. On the 31st day after hatching, a mean length of juveniles was 22.3±0.85 mm (n=5), and the number of fin rays was the same as that of adult fish with (iv8) dorsal fins and (iii8) anal fins.

Biochemical changes throughout early- and middle-stages of embryogenesis in lobsters (Homarus americanus) under different thermal regimes

Most marine crustacean eggs contain the full complement of nutritional resources required to fuel their growth and development. Given the propensity of many ovigerous (egg-bearing) American lobsters (Homarus americanus) to undergo seasonal inshore-to-offshore migrations, thereby potentially exposing their eggs to varying thermal regimes, the goal of this study was to determine the impact of water temperature on egg quality over their course of development. This was accomplished by documenting changes in total lipids, proteins, and size (volume) of eggs subjected to one of three thermal regimes: inshore, offshore, and constant (16 °C) conditions. Total egg lipids showed a marked decrease over time, while protein levels increased over the same period. Although there were no significant differences in total lipids, proteins, or egg sizes between eggs exposed to inshore and offshore temperatures, they differed from values for eggs exposed to a constant temperature, which also hatched almost three months sooner. This is most likely due to the fact that eggs held at a constant temperature did not experience a period of slow development during the colder months from November to March that are important for synchronizing egg hatch and may be compromised by elevated seawater temperatures.

Molecular characterization and functional analysis of components of the TOR pathway of the salmon louse, Lepeophtheirus salmonis (Krøyer, 1838)

The salmon louse Lepeophtheirus salmonis (Copepods, Caligida) is a marine ectoparasite infecting salmonid fishes in the northern hemisphere. At present, salmon lice infections are the most severe disease problem in the salmon farming industry causing significant economic losses. Due to development of resistance towards available chemotherapeutants, it is clear that new chemotherapeutants or non-chemical control methods are essential to manage the parasite in the future. The TOR signaling pathway is present in all metazoans and is a major regulator of cellular activity according to nutrient availability. In this study, we identified the TOR pathway genes in salmon louse; LsTSC1, LsTSC2, LsRheb, LsTOR, LsRaptor and LsRictor. RNA interference mediated gene silencing was performed to elucidate the functional role of each member of the pathway. Our results show that interference of the TOR signaling pathway either directly or indirectly inhibits many biological processes including egg maturation. In addition, the effect of gene knock-down results in more comprehensive physiological defects when targeting TORC1 and the upstream regulator Rheb. This is the first report on the TOR pathway in the salmon louse and that our research contributes to the basic knowledge of the parasite that could lead to development of novel treatment methods.

Early Life History of Rhodeus Fish (R. uyekii and R. ocellatus) in the Nakdong River Water System

The purpose of this study is to investigate the early life history of the Rhodeus fish, Rhodeus uyekii and R. ocellatus, in the Nakdong River to use as the preliminary data for the systematic study. The embryos used in the study were fertilized eggs (embryo) and larvae after artificial fertilization. The long diameter of the eggs of the R. uyekii was 3.39-3.97 mm (average 3.68±0.41 mm, n=30) and the short diameter was 1.36-1.55 mm (average 1.45±0.13 mm, n=30). The long diameter of the eggs of the R. ocellatus was 2.53-2.71 mm (average 2.62±0.12 mm, n=30) and the short diameter was 1.47-1.60 mm (average 1.53±0.09 mm, n=30). Hatching time was 48 hours for the R. uyekii and 50 hours for the R. ocellatus given that the average water temperature was 21.5°C. The hatched larvae were 4.95-5.00 mm (average 4.98±0.04 mm, n=5) for the R. uyekii and the total length was 3.66-3.69 mm (average 3.67±0.02 mm, n=5) for the R. ocellatus. R. uyekii was found to be 15.5-15.8 mm at total length (average 15.6±0.21 mm, n=5) on the 56 days after hatching with the number of dorsal fins being iii-9, anal fins iii-10, ventral fins iii-5. The R. ocellatus was found to be 15.8-16.0 mm (average 15.9±0.14 mm, n=5) at total length on the 58 days with the number of dorsal fins being iii-11, anal fins iii-12 and ventral fins iii-5 where the number of all fin stalks reached maximum.

Egg Development and Larvae and Juveniles Morphology of Carp, Cyprinus carpio in Korean

This study was conducted to observe egg and larvae morphological development of carp to obtain basic data for resource conservation and taxonomic research. Brood carp used in the research (total length 67.3-75.5 cm, average 71.0±3.45 cm) were bred in a circular rearing aquarium (600×300×100 cm) using a running water system from January to July, 2015. Breeding water temperature was maintained at 23.0-25.0℃(average 24.0℃). Fertilized carp eggs were translucent and globular, and their size was 1.75-1.89 mm (average 1.82±0.06 mm). Blastoderms formed 10 min after fertilization and reached the two-cell stage 30 min after fertilization. Then, the embryo turned dark and exhibited melanophores, and blood started flowing from the heart across the egg yolk at 42 hrs and 50 min after fertilization. Hatching began 70 hrs and 26 min after fertilization larvae emerged through the egg membrane, starting from the head. The length of prelarvae immediately after hatching was 5.23-5.38 mm (average 5.31±0.11 mm) the mouth and anus were closed, and the pectoral fin was formed. Postlarvae at 18 days after hatching had a total length of 11.9-13.9 mm (average 12.9±1.40 mm), separate anal fin and back membranes, and fin ray. Juveniles fish at 35 days after hatching had a total length of 29.9-30.2 mm (average 30.1±0.13 mm), with the body covered with scales, and the same number of fin rays, color, and shape as their broodstork.

The level of embryonation influences detection of Ostertagia ostertagi eggs by semi-quantitative PCR

BACKGROUND

The Internal Transcribed Spacer 2 (ITS2) is a candidate diagnostic marker of the pathogenic cattle nematode Ostertagia ostertagi. The aims of this study were: (i) to document and quantify how the development of O. ostertagi eggs affects ITS2 copies under different storage conditions, and (ii) to suggest optimal storage conditions for faecal samples in a diagnostic pipeline that involves detection and semi-quantification by real-time semi-quantitative polymerase chain reaction (qPCR).

FINDINGS

Eggs of Ostertagia ostertagi were obtained from fresh faeces and stored at 4 °C or 25 °C under aerobic or anaerobic (vacuum packing) conditions. Development was monitored by microscopy for up to 336 h, and the ITS2 copies were determined by qPCR from a fixed number of parasites. Under aerobic conditions at 25 °C, embryonation and a significant increase of ITS2 copies (P < 0.0001) were observed after 12 h. At 4 °C, embryonation occurred after 168 h with a trend towards increased ITS2 copies. Anaerobic conditions inhibited egg development at both temperatures and no significant increase in ITS2 copies was noticed (P = 0.90). ITS2 copies were analysed for each parasite stage: first-stage larvae (L1) exhibited significantly higher copy numbers (20,353 ± 1,950) than unembryonated eggs (568 ± 168; P < 0.0001) with lower coefficient of variation (33 vs 266 %).

CONCLUSIONS

Aerobic storage of O. ostertagi eggs at 25 °C led to a significant increase in ITS2 copies after 12 h due to embryonation and subsequent hatching. In contrast, anaerobic storage (vacuum packing) at 25 °C completely inhibited egg development and any undesirable semi-quantification bias for up to 336 h. Hence, vacuum packing is an optimal storage strategy prior to molecular diagnostic analyses. Alternatively, aerobic storage at 4 °C for up to 72 h can be used. Due to high copy numbers and lower genetic variation, the L1 stage may be considered for diagnostics and further molecular research.

Egg Development of the Ussurian Bullhead Fish, Leiocassis ussuriensis (Pisces: Bagridae) and Morphological Development of Its Larvae and Juveniles

This study was examined the ovogenesis of Ussurian bullhead, Leiocassis ussuriensis and the morphological development of its larvae and juveniles and to use the results as basic information for the preservation of species and resource enhancement. For artificial egg collection, human chorionic gonadotropin (HCG) was injected at a rate of 10 IU per gram of fish weight. During breeding period, water temperature maintained at 24.5~26.5°C (mean 25.0±0.05°C). The process of ovogenesis reached the two-cell stage in 50 minutes after fertilization. In 73 hours of fertilization the movement of the embryoid body became active state and the larvae began to hatch from the tail through the oolemma. Length of prelarvae were 6.33~6.50 mm long (mean 6.40±0.06 mm) just after hatching having yolk with their mouth not opened. After thirty eight days of hatching, juveniles were 30.6∼32.5 mm long (mean 31.5±0.65 mm). The color was dark yellowish brown throughout the entire body, and the number of caudal fin rays developed to thirty six perfectly.

Embryonation ability of Ascaridia galli eggs isolated from worm uteri or host faeces

Experimental infection models for Ascaridia galli rely on the use of eggs isolated either directly from worm uteri or from host faeces. We investigated whether A. galli eggs isolated from the two sources differ in their embryonation ability. A. galli eggs originating from 12 worm infrapopulations were isolated both from faeces of the living host (faecal eggs) and directly from worm uteri after host necropsy (uterine eggs). The isolated eggs from each infrapopulation and source were incubated in Petri dishes (n=24) containing a potassium-dichromate (0.1%) medium for 28 days (d) at room temperature. Starting from the day of egg isolation (d0), in ovo larval development was evaluated every second day by examining morphological characteristics of 200 eggs/petri dish. A total of 72,000 eggs were classified into undeveloped, early development, vermiform or fully embryonated stages. Isolation procedures caused similar damage to uterine and faecal eggs (2.2% and 0.5%, respectively; P=0.180). The first sign of in ovo embryonic development in faecal eggs (7%) was observed during the 24-h period when faeces were collected. On d28, a higher percentage of uterine eggs remained undeveloped when compared with faecal eggs (58.6% vs 11.0%; P<0.001). Although a higher (P<0.001) percentage of faecal eggs entered both the early developmental and vermiform stages, which took place primarily within the first two weeks of incubation, there was no time-shift between the development of faecal and uterine eggs. Starting from day 10, higher (P<0.05) percentages of faecal eggs completed embryonation compared with uterine equivalents. Eggs from both sources reached a plateau of embryonation by the end of 2nd week of incubation, with faecal eggs having a greater than two-fold higher embryonation ability. Cumulative mortality was higher in uterine eggs (14.3%) than in faecal eggs (0.2%). We conclude that faecal eggs have a higher embryonation ability than uterine eggs possibly due to maturation differences.

Spawning Behavior, Egg Development, Larvae and Juvenile Morphology of Hyphessobrycon eques (Pisces: Characidae) Characidae Fishes

Hyphessobrycon eques is a famous fish for ornamental fish market and aquarium. They are inhabit in regions of Amazon and Paraguay River basin. Serpae fishs were investigated 2-3 males are chased to female, and then males attempted to simulate the females abdomen. After fertilization, eggs were kept in incubators at 28°C. The fertilized eggs had adhesive and demesal characteristics and had a mean diameter of 0.92 ± 0.01 mm. Larvae hatched at 16 hrs post fertilization. The hatched larvae averaged 2.90 ± 0.16 mm in total length (LT ). Complete yolk sac resorption and mouth opening occurred on the third day post hatching. At 45 days post hatching, the larvae were 12.5 ± 1.60 mm LT and had reached the juvenile stage.

Blood serum and BSA, but neither red blood cells nor hemoglobin can support vitellogenesis and egg production in the dengue vector Aedes aegypti

Aedes aegypti is the major vector of dengue, yellow fever and chikungunya viruses that put millions of people in endemic countries at risk. Mass rearing of this mosquito is crucial for strategies that use modified insects to reduce vector populations and transmission of pathogens, such as sterile insect technique or population replacement. A major problem for vector mosquito mass rearing is the requirement of vertebrate blood for egg production since it poses significant costs as well as potential health hazards. Also, regulations for human and animal use as blood source can pose a significant obstacle. A completely artificial diet that supports egg production in vector mosquitoes can solve this problem. In this study, we compared different blood fractions, serum and red blood cells, as dietary protein sources for mosquito egg production. We also tested artificial diets made from commercially available blood proteins (bovine serum albumin (BSA) and hemoglobin). We found that Ae. aegypti performed vitellogenesis and produced eggs when given whole bovine blood, serum, or an artificial diet containing BSA. Conversely, egg production was impaired after feeding of the red blood cell fraction or an artificial diet containing only hemoglobin. We also found that egg viability of serum-fed mosquitoes were comparable to that of whole blood and an iron supplemented BSA meal produced more viable eggs than a meal containing BSA alone. Our results indicate that serum proteins, not hemoglobin, may replace vertebrate blood in artificial diets for mass mosquito rearing.

Spawning Behavior, Egg Development, Larvae and Juvenile Morphology of Hyphessobrycon eques (Pisces: Characidae) Characidae Fishes

Hyphessobrycon eques is a famous fish for ornamental fish market and aquarium. They are inhabit in regions of Amazon and Paraguay River basin. Serpae fishs were investigated 2-3 males are chased to female, and then males attempted to simulate the females abdomen. After fertilization, eggs were kept in incubators at 28°C. The fertilized eggs had adhesive and demesal characteristics and had a mean diameter of 0.92 ± 0.01 mm. Larvae hatched at 16 hrs post fertilization. The hatched larvae averaged 2.90 ± 0.16 mm in total length (LT ). Complete yolk sac resorption and mouth opening occurred on the third day post hatching. At 45 days post hatching, the larvae were 12.5 ± 1.60 mm LT and had reached the juvenile stage.

Early Life History of the Sevenband Grouper, Epinephelus septemfasciatus from Korea

This study is conducted to monitor the morphological developmental features of the egg development, larvae and juvenile of Epinephelus septemfasciatus, the fertilized eggs were gotton using artificial insemination. Matured parents are collected from marine caged fish farms in Geomun-ri, Samsan-myeon, Yeosu-si, Jeollanamdo Korea in June 2012. The fertilized eggs were pelagic eggs containing one oil globule, and measured 0.81~0.89 mm (0.85±0.04 mm, n=50) in diameter. In regard to rearing environment, the water temperature is 21.0~23.0°C and the salinity is 32.0~33.2‰. Hatching was observed from 48 hours after fertilization, the mouth and anus of prelarvae was not opened but had egg yolk at newly hatched. 4 days after hatching, the mouth and anus of postlarvae was opened and began to eat Rotifer and was measured 2.40~2.49 mm (2.45±0.03 mm n=10) in total length. 12 days after hatching, postlarvae was measured 3.77~4.67 mm (4.27±0.33 mm) in total length, its the second pole tide of dorsal fin and the first pole tide of pelvic fin was extended longitudinally. 71 days after hatching, juvenile was measured 40.5~45.4 mm (42.6±2.04 mm) in total length. Seven bands were observed in body, and pole tides of dorsal and pelvic fins were shortened.