[Co-exposure of carbon black and cadmium induces autophagy and inflammation in human bronchial epithelial cells via PERK pathway]

Objective: To investigate the effects of carbon black and cadmium (Cd) combined exposure on autophagy and inflammatory response mediated by protein kinase R-like endoplasmic reticulum kinase (PERK) pathway in human bronchial epithelial (16HBE) cells. Methods: In January 2022, human bronchial epithelial (16HBE) cells were resuscitated and cultured. Carbon black nanoparticles (CBNPs) were oxidized to adsorb Cd ions to construct "CBNPs-Cd" complexes. CCK-8 assay was used to detect the effects of different concentrations and time combinations of CBNPs and Cd on the viability of 16HBE cells. The subsequent dose groups were exposed to 2 μg/ml Cd, 100 μg/ml CBNPs, 100 μg/ml CBNPs+2 μg/ml Cd for 24 h. The number of autophagosomes and autolysosomes was detected by transmission electron microscopy. Western blotting was used to detect the protein expressions of PERK, eukaryotic initiation factor 2α (eIf2α), activating transcription factor 4 (ATF4), sequestosome 1 (SQSTM1/P62), and microtubule-associated protein 1 light chain 3 (LC3). After PERK gene was silenced by siRNA technology, the changes of autophagy marker proteins P62 and LC3 were detected, and the expressions of inflammatory factors interleukin-6 (IL6) and interleukin-8 (IL8) were detected by fluorescence quantitative PCR technique. One-way ANOVA analysis was used to compare three groups or more. LSD test was used for comparison between two groups. Factorial analysis was used for multivariate component analysis. Results: There was no significant change in cell viability of 16HBE after 24 h exposure to CBNPs and Cd alone or combined (P>0.05). Compared with the control group, the expressions of P62 and LC3 in 16HBE cells were significantly increased in the CBNPs and Cd alone/combined exposure group (P<0.05), and the number of autophagosomes and autophagolysosomes in the combined exposure group was increased compared with other groups. Compared with the control group, CBNPs and Cd alone exposure group had no significant effects on p-PERK/PERK and p-eIf2α/eIf2α protein expression (P>0.05). However, the protein expressions of p-PERK/PERK and p-eIf2α/eIf2α and ATF4 were all increased in the combined exposure group (P<0.05), and the levels of IL6 and IL8 in 16HBE cells in the combined exposure group of CBNPs and Cd were significantly higher than those in the control group (P<0.05). The levels of LC3 protein, IL6 and IL8 were decreased in the CBNPs-Cd combined exposure group after knockdown of PERK gene (P<0.05). The results of factorial analysis showed that exposure to CBNPs and Cd had significant effects on the expression of P62, LC3 and IL6 (P<0.05), but the interaction between the two chemicals had no statistical significance (P>0.05) . Conclusion: CBNPs-Cd combined exposure may inhibit autophagy and increase inflammation in human bronchial epithelial cells through activation of PERK-eIf2α-ATF4 pathway.

[Expression profile of circular RNA in inflammatory response in human bronchial epithelial cells induced by carbon black nanoparticles]

Objective: To explore the toxic effect of carbon black nanoparticles on human bronchial epithelial cells, and identify the differentially expressed circular RNA based on the full transcriptome high-throughput sequencing, so as to provide evidence for the development of biomarkers exposed to carbon black nanoparticles and their application on epigenetic toxicology. Methods: In June 2020, 16 HBE cells were treated with carbon black nanoparticles at concentrations of 20, 40 and 80 μg/ml, and 16 HBE cells without any intervention were used as the control group. The cytotoxicity of carbon black nanoparticles was detected by CCK8 and LDH experiments. Real-time quantitative fluorescent PCR (qRT-PCR) and ELISA were used to detect the changes of interleukin-6 (IL-6) and interleukin-8 (IL-6, IL-8) mRNA and protein levels of carbon black nanoparticles with concentration gradient after 72 h exposure. Western blot analysis was conducted to detect the expression levels of toll-like receptor 4 (TLR4), phosphorylated nuclear factor-κB (P-NF-κB), apoptosis-related speckled protein (ASC) and Caspase-1 associated with nuclear factor-κB. According to high-throughput sequencing results, differentially expressed Circrnas were screened and identified by qRT-PCR, and those with stable differentially expressed circrnas and the strongest association with the NF-κB pathway were selected for ring performance identification. Results: After being exposed to carbon black nanoparticles for 72 h, the activity of 16HBE cells decreased significantly (P<0.05), and the release of lactate dehydrogenase increased significantly (P<0.05). Compared with control group, mRNA expression levels of IL-6 and IL-8, protein levels of IL-6 and IL-8 were increased, and protein levels of TLR4, p-NF-κB, ASC and Caspase-1 were significantly up-regulated in 16 HBE cells of different concentrations, with statistical significance (P<0.05). Compared with the control group, a total of 492 differentially expressed circular Rnas (|log2 FC|>1) were detected. Among the 5 differentially expressed (P<0.05) circular Rnas, circ_002642 was selected as the object of subsequent research on circular Rnas, affter 72 hours of exposure to 80 μg/ml CBNPs, 16HBE cells showed signlficantly higher expression of circ_002642 (P<0.05) . Conclusion: Carbon black nanoparticles can induce differentially expressed circular RNAs associated with inflammatory response in human bronchial epithelial cells.

Changes in Red Color Sensitivity over the Spawning Cycle of Female Three-spined Stickleback (Gasterosteus aculeatus)

Male red nuptial coloration is a primary mating signal for three-spined sticklebacks (Gasterosteus aculeatus), and the retinae of both sexes are especially sensitive to red during the breeding season. Red sensitivity is an important aspect of female mate choice in this species, but only when they are ready to spawn and not over the entire breeding period. Here, we aimed to determine if the red sensitivity of female sticklebacks change over their repeat spawning cycle. To this end, we assessed retinal opsin mRNA levels and behavioral red sensitivity in females over this cycle. Both methods indicated that females were more sensitive to red during spawning than in the inter-spawning intervals. Relative expression levels of red color opsin genes (lws) and optical motor sensitivity were high during spawning, decreased after the spawning period, and then increased again 72-96 h later when they were ready to spawn again. Thus, female sticklebacks altered their color sensitivity according to need, but the underlying mechanism remains unclear.

Local negative permittivity and topological phase transition in polar skyrmions

Topological solitons such as magnetic skyrmions have drawn attention as stable quasi-particle-like objects. The recent discovery of polar vortices and skyrmions in ferroelectric oxide superlattices has opened up new vistas to explore topology, emergent phenomena and approaches for manipulating such features with electric fields. Using macroscopic dielectric measurements, coupled with direct scanning convergent beam electron diffraction imaging on the atomic scale, theoretical phase-field simulations and second-principles calculations, we demonstrate that polar skyrmions in (PbTiO₃)_n/(SrTiO₃)_n superlattices are distinguished by a sheath of negative permittivity at the periphery of each skyrmion. This enhances the effective dielectric permittivity compared with the individual SrTiO₃ and PbTiO₃ layers. Moreover, the response of these topologically protected structures to electric field and temperature shows a reversible phase transition from the skyrmion state to a trivial uniform ferroelectric state, accompanied by large tunability of the dielectric permittivity. Pulsed switching measurements show a time-dependent evolution and recovery of the skyrmion state (and macroscopic dielectric response). The interrelationship between topological and dielectric properties presents an opportunity to simultaneously manipulate both by a single, and easily controlled, stimulus, the applied electric field.

Phylogenetic analysis and ontogenetic changes in the cone opsins of the western mosquitofish (Gambusia affinis)

To convert external light into internal neural signal, vertebrates rely on a special group of proteins, the visual opsins. Four of the five types of visual opsins—short-wavelength sensitive 1 (Sws1), short-wavelength sensitive 2 (Sws2), medium-wavelength sensitive (Rh2), and long-wavelength sensitive (Lws)—are expressed in cone cells for scotopic vision, with the fifth, rhodopsin (Rh1), being expressed in rod cells for photopic vision. Fish often display differing ontogenetic cone opsin expression profiles, which may be related to dietary and/or habitat ontogenetic shift. The western mosquitofish (Gambusia affinis) is an aggressive invader that has successfully colonized every continent except Antarctica. The strong invasiveness of this species may be linked to its visual acuity since it can inhabit turbid waters better than other fishes. By genome screening and transcriptome analysis, we identify seven cone opsin genes in the western mosquitofish, including one sws1, two sws2, one rh2, and three lws. The predicted maximal absorbance wavelength (λ_max) values of the respective proteins are 353 nm for Sws1, 449 nm for Sws2a, 408 nm for Sws2b, 516 nm for Rh2-1, 571 nm for Lws-1, and 519 nm for Lws-3. Retention of an intron in the lws-r transcript likely renders this visual opsin gene non-functional. Our real-time quantitative PCR demonstrates that adult male and female western mosquitofish do not differ in their cone opsin expression profiles, but we do reveal an ontogenetic shift in cone opsin expression. Compared to adults, larvae express proportionally more sws1 and less lws-1, suggesting that the western mosquitofish is more sensitive to shorter wavelengths in the larval stage, but becomes more sensitive to longer wavelengths in adulthood.

The Effects of Continuous Acoustic Stress on ROS Levels and Antioxidant-related Gene Expression in the Black Porgy (Acanthopagrus schlegelii)

Hao-Yi Chang, Tzu-Hao Lin, Kazuhiko Anraku, and Yi Ta Shao (2018) Short-term exposure to strong underwater noise is known to seriously impact fish. However, the chronic physiological effects of continuous exposure to weak noise, i.e. the operation noise from offshore wind farms (OWF), remain unclear. Since more and more OWF will be built in the near future, their operation noise is an emerging ecological issue. To investigate the long-term physiological effects of such underwater noise on fish, black porgies (Acanthopagrus schlegelii) were exposed to two types of simulated wind farm noise-quiet (QC: 109 dB re 1 μPa / 125.4 Hz; approx. 100 m away from the wind turbine) and noisy (NC: 138 dB re 1 μPa / 125.4 Hz; near the turbine)-for up to 2 weeks. Measurement of auditory-evoked potentials showed that black porgies can hear sound stimuli under both NC and QC scenarios. Although no significant difference was found in plasma cortisol levels, the fish under NC conditions exhibited higher plasma reactive oxygen species (ROS) levels than the control group at week 2. Moreover, alterations were found in mRNA levels of hepatic antioxidant-related genes (sod1, cat and gpx), with cat downregulated and gpx upregulated after one week of QC exposure. Our results suggest that the black porgy may adapt to QC levels of noise by modulating the antioxidant system to keep ROS levels low. However, such antioxidant response was not observed under NC conditions; instead, ROS accumulated to measurably higher levels. This study suggests that continuous OWF operation noise represents a potential stressor to fish. Furthermore, this is the first study to demonstrate that chronic exposure to noise could induce ROS accumulation in fish plasma.

Largescale mullet (Planiliza macrolepis) can recover from thermal pollution-induced malformations

It is well known in aquaculture that hyperthermic perturbations may cause skeleton malformations in fish, but this phenomenon has rarely been documented in wild species. One rare location where thermal pollution has increased the proportion of malformed fish in wild population is in the waters near the Kuosheng Nuclear Power Plant in Taiwan. At this site, the threshold temperature and critical exposure time for inducing deformations have not been previously determined. In addition, it was unclear whether juvenile fish with thermal-induced malformations are able to recover when the temperature returns below the threshold. In the present study, juvenile largescale mullet (Planiliza macrolepis) were kept at temperatures ranging from 26°C and 36°C for 1–4 weeks, after which malformed fish were maintained at a preferred temperature of 26°C for another 8 weeks. The vertebrae bending index (VBI) of fish was increased after 2 weeks at 36°C, and deformed vertebral columns were detected by radiography after 4 weeks. However, malformations were not observed in groups kept at or below 34°C. Moreover, at the end of the recovery period, both the VBI and the vertebrae malformations had returned to normal. The results of this study may help to more precisely determine potential environmental impacts of thermal pollution and raise the possibility that the capacity for fish vertebrae to recover from the impacts of chronic thermal exposures may be an important consideration in marine fish conservation.

Hormonal changes over the spawning cycle in the female three-spined stickleback, Gasterosteus aculeatus

Female three-spined sticklebacks are batch spawners laying eggs in a nest built by the male. We sampled female sticklebacks at different time points, when they were ready to spawn and 6, 24, 48 and 72h post-spawning (hps) with a male. Following spawning, almost all females (15 out of 19) had ovulated eggs again at Day 3 post-spawning (72hps). At sampling, plasma, brain and pituitaries were collected, and the ovary and liver were weighed. Testosterone (T) and estradiol (E2) were measured by radioimmunoassay. Moreover, the mRNA levels of follicle-stimulating hormone (fsh-β) and luteinizing hormone (lh-β) in the pituitary, and of the gonadotropin-releasing hormones (GnRHs: gnrh2, gnrh3) and kisspeptin (kiss2) and its G protein-coupled receptor (gpr54) in the brain were measured by real-time qPCR. Ovarian weights peaked in "ready to spawn" females, dropped after spawning, before again progressively increasing from 6 to 72hps. Plasma T levels showed peaks at 24 and 48hps and decreased at 72hps, while E2 levels increased already at 6hps and remained at high levels up to 48hps. There was a strong positive correlation between T and E2 levels over the spawning cycle. Pituitary lh-β mRNA levels showed a peak at 48hps, while fsh-β did not change. The neuropeptides and gpr54 did not show any changes. The changes in T and E2 over the stickleback spawning cycle were largely consistent with those found in other multiple-spawning fishes whereas the marked correlation between T and E2 does not support T having other major roles over the cycle than being a precursor for E2.

The effects of continuously acoustical stress on cortisol in milkfish (Chanos chanos)

Strong underwater acoustic noise has been known that may cause hearing loss and actual stress in teleost. However, the long-term physiological effects of relatively quiet but continuously noise on fish were less understood. In present study, milkfish, Chanos chanos, were exposed to the simulated-wind farm noise either quiet (109dB re 1μPa/125.4Hz; approx. 10-100m distant from the wind farm) or noisy (138dB re 1μPa/125.4Hz; nearby the wind farm) conditions for 24h, 3days and 1week. Comparing to the control group (80dB re 1μPa/125.4Hz), the fish exposed to noisy conditions had higher plasma cortisol levels in the first 24h. However, the cortisol levels of 24h spot returned to the resting levels quickly. The fish exposed under noisy condition had significantly higher head kidney star (steroidogenic acute regulatory) and hsd11b2 (11-β-hydroxysteroid dehydrogenase 2) mRNA levels at the following treatment time points. In addition, noise exposure did not change hypothalamus crh (Corticotropin-releasing hormone) mRNA levels in this experiment. The results implied that the weak but continuously noise was a potential stressor to fish, but the impacts may be various depending on the sound levels and exposure time. Furthermore, this study showed that the continuous noise may up-regulate the genes that are related to cortisol synthesis and possibly make the fish more sensitive to ambient stressors, which may influence the energy allocation appearance in long-term exposures.

Differentiation of visual spectra and nuptial colorations of two Paratanakia himantegus subspecies (Cyprinoidea: Acheilognathidae) in response to the distinct photic conditions of their habitats

BACKGROUND

Vision, an important sensory modality of many animals, exhibits plasticity in that it adapts to environmental conditions to maintain its sensory efficiency. Nuptial coloration is used to attract mates and hence should be tightly coupled to vision. In Taiwan, two closely related bitterlings (Paratanakia himantegus himantegus and Paratanakia himantegus chii) with different male nuptial colorations reside in different habitats. We compared the visual spectral sensitivities of these subspecies with the ambient light spectra of their habitats to determine whether their visual abilities correspond with photic parameters and correlate with nuptial colorations.

RESULTS

Theelectroretinogram (ERG) results revealed that the relative spectral sensitivity of P.h. himantegus was higher at 670 nm, but lower at 370 nm, than the sensitivity of P. h. chii. Both bitterlings could perceive and reflect UV light, but the UV reflection patterns differed between genders. Furthermore, the relative irradiance intensity of the light spectra in the habitat of P. h. himantegus was higher at long wavelengths (480-700 nm), but lower at short wavelengths (350-450 nm), than the light spectra in the habitats of P. h.chii.

CONCLUSIONS

Two phylogenetically closely related bitterlings, P. h. himantegus and P. h. chii, dwell in different waters and exhibit different nuptial colorations and spectral sensitivities, which may be the results of speciation by sensory drive. Sensory ability and signal diversity accommodating photic environment may promote diversity of bitterling fishes. UV light was demonstrated to be a possible component of bitterling visual communication. The UV cue may assist bitterlings in genderidentification.

Malondialdehyde and SOD-induced changes of gastric tissues in acute gastric mucosal injury under positive acceleration

The aim of this study was to investigate the impacts of positive acceleration (+Gz) on the gastric mucosal tissues in cases of acute gastric mucosal injury and to explore the role of oxygen free radicals. Thirty Sprague Dawley rats were randomly divided into the absolute ethanol control group (A group), absolute ethanol +5Gz group (B group), absolute ethanol +10Gz group (C group). Following centrifugation, the gastric tissues of each group were studied for the presence of gastric mucosal injuries and morphological changes. The concentrations of malondialdehyde (MDA) and superoxide dismutase (SOD) contents were simultaneously investigated. Degree of gastric mucosal injuries were as follows: C group (visually 49.080 ± 10.254, under light microscopy 9.400 ± 2.011) > B group (visually 23.654 ± 9.678, under light microscopy 5.000 ± 1.054) > A group (visually 11.410 ± 3.742, under light microscopy 3.800 ± 1.399). The gastric mucosal MDA content (0.376 ± 0.084 vs 0.235 ± 0.044) was significantly higher in the C group than in the A group, whereas the SOD content (8.852 ± 1.001 vs 10.694 ± 0.965) was lower than that in the A group. However, the MDA and SOD contents did not change much in the B group. Our results suggest that the +Gz exposure might aggravate the acute gastric mucosal injury, and changes in MDA and SOD contents in the gastric tissues indicated that the oxygen free radicals play an important role in this regard.

Androgens increase lws opsin expression and red sensitivity in male three-spined sticklebacks

Optomotor studies have shown that three-spined sticklebacks (Gasterosteus aculeatus) are more sensitive to red during summer than winter, which may be related to the need to detect the red breeding colour of males. This study aimed to determine whether this change of red light sensitivity is specifically related to reproductive physiology. The mRNA levels of opsin genes were examined in the retinae of sexually mature and immature fish, as well as in sham-operated males, castrated control males, or castrated males implanted with androgen 11-ketoandrostenedione (11 KA), maintained under stimulatory (L16:D8) or inhibitory (L8:D16) photoperiods. In both sexes, red-sensitive opsin gene (lws) mRNA levels were higher in sexually mature than in immature fish. Under L16:D8, lws mRNA levels were higher in intact than in castrated males, and were up-regulated by 11 KA treatment in castrated males. Moreover, electroretinogram data confirmed that sexual maturation resulted in higher relative red spectral sensitivity. Mature males under L16:D8 were more sensitive to red light than males under L8:D16. Red light sensitivity under L16:D8 was diminished by castration, but increased by 11 KA treatment. Thus, in sexually mature male sticklebacks, androgen is a key factor in enhancing sensitivity to red light via regulation of opsin gene expression. This is the first study to demonstrate that sex hormones can regulate spectral vision sensitivity.

The auditory roles of the gas bladder and suprabranchial chamber in walking catfish (Clarias batrachus)

Background

The enhanced auditory abilities of certain fish are dependent on specialized hearing structures. Several gas-holding structures, including the suprabranchial chamber, otic gas bladder, and Weberian apparatus-linked gas bladder, have been demonstrated to improve the hearing ability of fish. The walking catfish (Clarias batrachus), a benthic species, is unique in that it has both a suprabranchial chamber (SC) and a Weberian apparatus-linked, encapsulated gas bladder (WGB). This study aimed to investigate the respective roles of these two structures in contributing to the overall hearing ability of walking catfish.

Results

The auditory evoked potentials method was used to measure hearing thresholds in intact fish and fish with a deflated WGB and/or SC. Gas removal from the WGB increased auditory thresholds at all frequencies tested (0.4 to 5.0 kHz), whereas injection of water into the SC shifted the threshold only at frequencies below 3.0 kHz. However, such a correlation was not observed for the SC at 4.0 and 5.0 kHz.

Conclusions

The findings indicated that both the encapsulated WGB and the SC had an accessory auditory role. However, WGB enhanced hearing abilities in the whole frequency range, whereas SC did not.

Androgen feedback effects on LH and FSH, and photoperiodic control of reproduction in male three-spined sticklebacks, Gasterosteus aculeatus

Sexual maturation in the stickleback is controlled by photoperiod. The aim of this study was to find out whether changes in feedback effects exerted by sex steroids could mediate the photoperiodic effect, which is regarded to be of an all-or-nothing character. To that end, males were castrated and treated with different doses of testosterone (T) and in one experiment also with the aromatase inhibitor fadrozole (AI) and kept under different photoperiods. In control fish, long day (LD 16:8) stimulated maturation, associated with more hypertrophied kidneys (a secondary sexual character) and higher levels of pituitary lhb and fshb mRNA than under short day conditions (LD 8:16). Under LD 8:16, low doses of T suppressed both lhb and fshb mRNA levels. However, with the use of high doses of T and/or longer photoperiods the inhibitory effects on lhb and fshb mRNA levels became less clear or instead positive effects were observed. Under intermediate photoperiod conditions, the negative feedback effect of a low dose of T on fshb was more prominent with shorter photoperiods, whereas no such shift was observed for lhb mRNA. The inhibitory effect of the low dose of T on lhb mRNA levels under LD 8:16 was abolished by AI, whereas the stimulatory effect of the high dose of T was not. The negative feedback effects were more marked under short days than under long days, whereas positive feedback effects were more marked under long days. The suppression of both fshb and lhb mRNA levels by low androgen levels, especially under short days, may inhibit maturation completely unless a rise of androgens above threshold levels would allow complete maturation.

Schistocephalus solidus infections increase gonadotropins and gonadotropin releasing hormone (GnRH3) mRNA levels in the three-spined stickleback, Gasterosteus aculeatus

Parasites often impair the reproduction of their hosts, one well known case being the cestode Schistocephalus solidus which is a common parasite in three-spined sticklebacks, Gasterosteus aculeatus. One of the possible ways that this could be exerted is by suppression on the brain-pituitary-gonadal (BPG) axis. In this study, mRNA levels of FSH-β and LH-β and of GnRH2 (cGnRH II) and GnRH3 (sGnRH) were measured via Q-PCR in infected and uninfected fish sampled from the field a few weeks before the onset of breeding. The pituitary mRNA levels of both FSH-β and LH-β were higher in infected males than in uninfected males. Also in females, FSH-β mRNA levels were higher in infected individuals than in others, whereas there was no significant difference found in LH-β expression. Brain mRNA levels of GnRH3 were higher in infected fish than in uninfected fish in both sexes, but no difference was found in GnRH2 mRNA levels. Thus, infection by S. solidus was able to alter the expressions not only of gonadotropins (GtHs), but also of GnRH which has not been observed previously. However, the effects are opposite to what should be expected if the parasite suppressed reproduction via actions on the brain-pituitary level. The gonads are perhaps more likely to be impaired by the parasites in other ways, and changed feedbacks on the BPG axis could then lead to the increases in GtHs and GnRH.