Swim Bladder Research Articles

Rupture of Brumadinho dam (Minas Gerais, Brazil): embryotoxicity in zebrafish induced by metal mixture-contaminated water

Rupture of dam B-1 at the Córrego do Feijão mine in Brumadinho, state of Minas Gerais, Brazil (25/Jan/2019) contaminated the Paraopeba River with mine waste. To identify the adverse effects of this event on public and environmental health, we conducted the Fish Embryo Acute Toxicity (FET) test (OECD No. 236). During the tests, zebrafish embryos were exposed for 144 hours to solutions containing realistic concentrations of dissolved iron and aluminum and total manganese at the following analysis points upstream or downstream of the dam: 10 km, upstream; 19.7 km, downstream, at the point where water for consumption is collected; 24.5 km, downstream, in the city of Mário Franco; and 59 km, downstream, on the border between the towns of Juatuba and Betim. Metal concentrations were taken from September 2019 report No. 53 released by IGAM. Mortality was high at all exposure points and reached 93% at the Juatuba/Betim point. We also detected lethal, sublethal and teratogenic effects, such as non-hatching, non-inflation of the swim bladder, pericardial edema and scoliosis, affecting up to 25% of embryos at the other analysis points. The results highlight the need for continuous monitoring of the water quality of the Paraopeba River.

Developmental toxicity of glyphosate on embryo-larval zebrafish (Danio rerio)

Glyphosate (GLY) induces developmental toxicity in fish, but research on the toxicity mechanism is limited. In this study, zebrafish embryos were exposed for 120 hpf to 0.7, 7, and 35 mg L-1 GLY. The results show that GLY treatment induced developmental toxicity in the fish, including premature hatching, reduced heartbeats, pericardial and yolk sac oedema, swim bladder deficiency, and shortened body length, which was possibly due to a significantly decreased triiodothyronine (T3)/thyroxine (T4) ratio and the abnormal expression patterns of hypothalamic-pituitary-thyroid (HPT) (crh, tshβ, tr α, tr β, and t tr ) and growth hormone/insulin-like growth factor (GH/IGF) axis-related genes (gh, ghrα, ghrβ, igf1, igf1rα, and igf1rβ) in larvae exposed to GLY. In addition, GLY exposure altered the levels of SOD and CAT, increased ROS, promoted malondialdehyde (MDA) content, and significantly altered the levels of endoplasmic reticulum (ER) stress signalling pathway factors (perk, eif2α, gadd34, atf4, ire1α, xbp1, atf6, hspa5, and chop), suggesting that GLY treatment induced oxidative injury and ER stress in the larvae. Further research showed that treatment with a higher concentration of GLY upregulated the levels of iNOS, IL-1β, and TNF-α while inhibiting the expression of IL-10 and TGF-β, suggesting that GLY causes an inflammatory reaction in the larvae. In addition, we also found that apoptosis was induced in the larvae, which was determined by acridine orange staining and abnormal expression of p53, caspase-3, -8, and -9. Taken together, our results demonstrate that GLY exposure altered the T3/T4 ratio, disturbed the expression patterns of HPT and GH/IGF axis-related genes, and induced oxidative and ER stress, inflammatory reactions, and apoptosis in the zebrafish larvae. This investigation contributes to improved understanding of the developmental toxicity mechanism of GLY in fish.

Teleost swim bladder, an ancient air-filled organ that elicits mucosal immune responses

The air-filled organs (AOs) of vertebrates (lungs and swim bladders) have evolved unique functions (air-breathing or buoyancy control in water) to adapt to different environments. Thus far, immune responses to microbes in AOs have been described exclusively in the lungs of tetrapods. Similar to lungs, swim bladders (SBs) represent a mucosal surface, a feature that leads us to hypothesize a role for SB in immunity. In this study, we demonstrate that secretory IgT (sIgT) is the key SB immunoglobulin (Ig) responding to the viral challenge, and the only Ig involved in viral neutralization in that organ. In support of these findings, we found that the viral load of the SB from fish devoid of sIgT was much higher than that of control fish. Interestingly, similar to the lungs in mammals, the SB represents the mucosal surface in fish with the lowest content of microbiota. Moreover, sIgT is the main Ig class found coating their surface, suggesting a key role of this Ig in the homeostasis of the SB microbiota. In addition to the well-established role of SB in buoyancy control, our findings reveal a previously unrecognized function of teleost SB in adaptive mucosal immune responses upon pathogenic challenge, as well as a previously unidentified role of sIgT in antiviral defense. Overall, our findings indicate that despite the phylogenetic distance and physiological roles of teleost SB and mammalian lungs, they both have evolved analogous mucosal immune responses against microbes which likely originated independently through a process of convergent evolution.

PREVALENCE OF THE Anguillicola crassus PARASITE IN THE INTERNATIONAL MINHO RIVER

The European eel, Anguilla anguilla (Linnaeus, 1758), is vulnerable to infections by the parasitic nematode Anguillicola crassus Kuwahara, Niimi & Itagaki, 1974, mainly in freshwater ecosystems. The eel is a bioindicator species due to its benthic behaviour, predator, and life cycle. The parasite feeds on blood from the eel's swim bladder, causing damage to the walls and deterioration of this organ, reducing energy reserves, and affecting its migratory capacity for reproduction. Eels were captured at different sampling points divided into 4 areas of the international section of the Minho River in the following time periods: 1995-96, 2008-2011 and 2017-2021, through fyke nets and electric fishing sampling techniques. The objectives of this work were to analyze the dispersion and prevalence of A. crassus in the Minho River basin over time, infection rates and the eels condition. The prevalence levels found reach values ​​close to 75% in some sampled locations and 99% of eels shown pathological signs of swim bladder infection. The nematode dispersal area increased since the early 1990s when its presence in the Minho River was first recorded.

Tpo knockout in zebrafish partially recapitulates clinical manifestations of congenital hypothyroidism and reveals the involvement of TH in proper development of glucose homeostasis

Congenital hypothyroidism (CH) is a highly prevalent but treatable neonatal endocrine disorder. Thyroid peroxidase (TPO) catalyzes key reactions in thyroid hormone (TH) synthesis. TPO mutations have been found to underlie approximately 5% of congenital hypothyroidism in Chinese patients with more severe phenotypes, the treatment of whom usually requires a higher dose of L-thyroxine. The Tpo gene of zebrafish has 66% homology with the human TPO gene, and synteny analysis has indicated that it is likely a human TPO ortholog. In this study, we generated a tpo-/- mutant zebrafish line through knockout of tpo with CRISPR/Cas9 and investigated the associated phenotypes. Tpo-/- mutant zebrafish displayed growth retardation; an increased number of thyroid follicular cells; and abnormal extrathyroidal phenotypes including pigmentation defects, erythema in the thoracic region, delayed scale development and failure of swim bladder secondary lobe formation. All these abnormal phenotypes were reversed by 30 nM thyroxine (T4) treatment starting at 1 month of age. Tpo-/- mutants also showed increased glucose levels during larval stages, and the increases were induced at least in part by increasing glucagon and decreasing insulin expression. Our work indicates that tpo-mutant zebrafish may serve as a human congenital hypothyroidism model for studying TPO- and TH-related disease mechanisms.

Effect of thyroid hormone-disrupting chemicals on swim bladder inflation and thyroid hormone-related gene expression in Japanese medaka and zebrafish.

We compared the influence of thyroid hormone-disrupting chemicals (heptafluorobutanoic acid, PFBA and tris[1,3-dichloro-2-propyl] phosphate, TDCPP) and thyroid hormone (3,3',5-triiodo-L-thyronine, T3) on swim bladder inflation and thyroid hormone-related gene expression in Japanese medaka and zebrafish. The swim bladder of most larvae had inflated at 4h post hatching (hph) in Japanese medaka and at 48 hph in zebrafish in controls. In both fish species, the swim bladder inflation was inhibited in larvae exposed to PFBA (lowest observed effect concentration [LOEC] in medaka: 40 mg/L; in zebrafish: 80 mg/L), TDCPP (LOEC in medaka: 1mg/L; in zebrafish: 0.5mg/L), and T3 (no inhibition in Japanese medaka; LOEC in zebrafish: 7.5μg/L). We also examined the influence of PFBA, TDCPP, and T3 on the expression of thyroid stimulating hormone subunit beta (tshβ) or thyroid hormone receptor alpha (trα) and beta (trβ). No changes were observed in the expression of genes after PFBA and TDCPP exposure; however, T3 exposure upregulated trα and trβ expression in both fish species. When the results were compared between Japanese medaka and zebrafish, swim bladder inflation in both species was found to be inhibited by exposure to thyroid hormone-disrupting chemicals. Our results show that inhibition of the swim bladder inflation at 4 hph in Japanese medaka and 48 hph in zebrafish is a potential indicator of thyroid hormone-disturbing activity of chemicals.

Cloning, tissue distribution and mRNA expression of type I collagen alpha 1 gene from Chu's croaker (Nibea coibor)

The demand for collagen has been increasing over years due to its wide application in food, cosmetics and biomedicine industries. The synthesis of collagen protein in fish depends on instructions provided by collagen, type I, alpha 1 (COL1A1) gene. However, cloning, tissue distribution and mRNA expression of COL1A1 gene in a gel-producing Chu's croaker (Nibea coibor) is currently unknown. This study cloned the cDNA of COL1A1 gene (GenBank accession number: MK641512) from six N. coibor fish. The distribution and mRNA expression pattern of COL1A1 was analyzed in eight tissues of N. coibor. The COL1A1 cDNA had a full length of 6130 bp and contained a 4344 bp open reading frame (ORF) encoding a polypeptide of 1448 amino acids. The homology of N. coibor COL1A1 amino acid had 98% similarity with Larimichthys crocea, indicating conservatism with other members in same family (Sciaenidae). The deduced polypeptide contained the same signal peptides, C-propeptide and N-propeptide domains, and triple helix domains, which are the characteristics of type I collagen in vertebrates. The mRNA of COL1A1 gene was expressed significantly higher in the spine of N. coibor than in all other tissues (P < 0.05), followed by swim bladder, skin and scales. The swim bladder had higher collagen and hydroxyproline contents than other tissues, followed by spine >, scales > and > skin (P < 0.05). Our study successfully cloned the COL1A1 gene from N. coibor for the first time. The COL1A1 gene contained all the features of collagen pro-α1(I) chain proteins, and shared high homology with other marine teleost. COL1A1 gene in N. coibor is highly expressed in spine and swim bladder, consistent with collagen distribution. Our study contributes to better understanding on collagen biosynthesis in N. coibor tissues for various industrial uses.

Effect of salinity on embryonic development eggs hatching rate and of larvael survival of Common Carb

This study focus upon the beneficial capability of brackish water embryonic development hatching fish eggs embryo genes of common carp, Cyprinus carpio ( L.). different concentrations were used. (2-16‰). The aeration hatching technique was used in the hatching of eggs, and the hatched larvae were incubated in the same salt concentrations. The nursing was done in plastic containers for eight weeks in the same salt concentrationsThe results showed that the higher ratio of development of the embryos which was 94% at salt concentration of 6‰ after the first six hours of the eggs incubation, and decreased to85.5% in the concentration of 6‰ after 48 hours of incubation. The period of hatching of eggs ranged between 52-72 hours in the concentrations 2-12‰ . The high survival ratio for larvae was 95 % at the salinity of 2 ‰, while the embryo died directly after hatching at the salinity 12‰.The duration of yolk sac absorption for common carp larvae were ranged between 2-3 days at the salinity of 2‰ and 5-7 days at the salinity of 8‰.The gas bladder of the common carp appeared within 3-4 days at the 2 and 4‰ .average weight 1.9 g in the salinity of 4‰ and the lowest weight was 0.72g of salinity of 8‰The highest average daily weight gain increased for common carp and it was 0.0344 g at salinity of 4‰.

Morphophysiological features of producers of carp cultivated in the pond of the UOKH KSTU

The purpose of this study was to study morphophysiological signs in fish from the brood stock of carp grown in the educational and experimental farm of KSTU. The object of the study was fish from the senior repair group entering the breeding stock for the first time. The research was carried out during the spring fishing of winter repair ponds. Clinically healthy individuals with no abnormalities in the development of the body, fins and head were selected for the representativeness of the studies. Morphophysiological indicators of fish were evaluated using the method of morphophysiological indicators. After determining the exterior and meristic features of the fish, they were opened, determining the mass of internal organs and the length of the intestine. Based on these studies, the indices of internal organs and intestines were calculated according to standard methods. The value of the index of intestinal length in female carp averaged 158.77, and in males 198.75%. The ratio of the anterior part of the swim bladder to the posterior is 1.13 in females, and 1.12 in males. The study of organ indices showed that for females the spleen index was 0.76, for males 0.75%; the gill index was 4.34% for females, 4.13% for males; the liver index is 4.76 and 3.05%, respectively. The gonadosomatic index (GSI) for female carp averaged 50.32%, for males 26.59%. Thus, when analyzing morphophysiological indicators in the first-time spawning males and females of carp, it was found that in terms of the index of intestinal length and the relative length of the intestine, as well as the ratio of the chambers of the swim bladder, the producers of carp grown at the KSTU g are close to “wild” carp or carp. This is probably the result of the specific growing conditions at this enterprise. All values of other morphophysiological indicators in the studied carp producers can be considered satisfactory.

Functional Adaptation of Vocalization Revealed by Morphological and Histochemical Characteristics of Sonic Muscles in Blackmouth Croaker (Atrobucca nibe).

Simple SummarySound production is common in numerous fish species. Some species can emit calls through the contraction of specialized muscles called sonic or drumming muscles. The sonic muscles of fish are among the fastest muscles in vertebrates. Although numerous studies have investigated the mechanism underlying sound production in fish, only the distinct features of the sonic muscles of a few species have been investigated. We demonstrated that the sonic muscles have functionally adapted for fast twitching and fatigue resistance, which support vocalization in the blackmouth croaker (Atrobucca nibe).Sound production in the blackmouth croaker (Atrobucca nibe) was characterized using acoustic, morphological, and histochemical methods. Their calls consisted of a train of two to seven pulses; the frequency ranged from 180 to 3000 Hz, with a dominant frequency of 326 ± 40 Hz. The duration of each call ranged from 80 to 360 ms. Male A. nibe possess a pair of bilaterally symmetric sonic muscles attached to the body wall adjacent to the swim bladder. The average diameter of the sonic muscle fibers was significantly shorter than that of the abdominal muscle fibers. Semithin sections of the sonic muscle fibers revealed a core-like structure (central core) and the radial arrangement of the sarcoplasmic reticulum and myofibrils. Numerous mitochondria were distributed within the central core and around the periphery of the fibers. Most of the fibers were identified as Type IIa on the basis of their myosin adenosine triphosphatase activities, but a few were identified as Type IIc fibers. All sonic muscle fibers exhibited strong oxidative enzyme activity and oxidative and anaerobic capabilities. The features suggest that the sonic muscles of A. nibe are morphologically and physiologically adapted for fast twitching and fatigue resistance, which support fish vocalization.

Exploring Zebrafish Larvae as a COVID-19 Model: Probable Abortive SARS-CoV-2 Replication in the Swim Bladder.

Animal models are essential to understanding COVID-19 pathophysiology and for preclinical assessment of drugs and other therapeutic or prophylactic interventions. We explored the small, cheap, and transparent zebrafish larva as a potential host for SARS-CoV-2. Bath exposure, as well as microinjection in the coelom, pericardium, brain ventricle, or bloodstream, resulted in a rapid decrease of SARS-CoV-2 RNA in wild-type larvae. However, when the virus was inoculated in the swim bladder, viral RNA stabilized after 24 h. By immunohistochemistry, epithelial cells containing SARS-CoV-2 nucleoprotein were observed in the swim bladder wall. Our data suggest an abortive infection of the swim bladder. In some animals, several variants of concern were also tested with no evidence of increased infectivity in our model. Low infectivity of SARS-CoV-2 in zebrafish larvae was not due to the host type I interferon response, as comparable viral loads were detected in type I interferon-deficient animals. A mosaic overexpression of human ACE2 was not sufficient to increase SARS-CoV-2 infectivity in zebrafish embryos or in fish cells in vitro. In conclusion, wild-type zebrafish larvae appear mostly non-permissive to SARS-CoV-2, except in the swim bladder, an aerial organ sharing similarities with the mammalian lung.

Determination of the swim bladder parasite Anguillicola crassus (Nematoda, Dracunculoidea) in the European Eel, Anguilla anguilla (Linnaeus, 1758) from the locality Çamalti Tuzla of Izmir Bay, Eastern Aegean Sea

We, here, aimed to determine the presence of Anguillicola crassus, a swim bladder parasite, in 89 (male: 45, female: 44) dead European eel specimens obtained seasonally between 2020-2021 from a regional fisherman, who has fished with fyke net in the locality Tuzla of Izmir Bay, Eastern Aegean Sea. Out of 21 male European eels caught in winter, only one specimen (TL: 48.5 cm and TW: 247.12 g) had 23 swim bladder parasites (adult nematodes: 15, larvae: 8) and similarly, only one parasite was found in one specimen (TL: 37.5 cm and TW: 88.47 g) of 8 eels caught in spring. No parasite was found in the female eels. At the examinations, it was determined that all adult Anguillicola crassus specimens were females and the minimum-maximum and average length values in adult and larval parasites were, respectively, 1.5-2.5 cm (1.99 ± 0.31) and 0.7-1.3 cm (1.025 ± 2.40). Consequently, the species A. crassus, a swim bladder parasite, was found in European eels from the locality Çamalti Tuzla in two seasons (winter and spring) and this parasitic nematode were only in male eels. This study is a first and remarkable one having evidential value, which shows the presence of the species A. crassus among the eel population in the locality Çamalti Tuzla of Izmir Bay. Besides, it is a population that should be monitored due to the status of Anguilla anguilla on the IUCN red list.

Probiotic Treatment Enhances Pre-feeding Larval Development and Early Survival in Zebrafish Danio rerio.

The growth and development of healthy culture subjects are essential in increasing productivity in the aquaculture industry. A primary determinant of aquatic animal productivity is the ambient microbial population. If an aquatic animal's microbiome is diverse, with bacteria favoring beneficial over pathogenic species, the health and growth of the animal (i.e., fish or crustacean) can be substantially improved. Embryonic and newly hatched Zebrafish Danio rerio larvae were reared in the presence of (1) water from the broodstock culture tank as a control, (2) a probiotic solution containing 19 strains of live lactic acid bacteria (LAB), or (3) an antibiotic (AB) solution with amoxycillin. Developmental parameters were monitored until 10 d postfertilization. Bacteria present in the water and larvae were cultured and identified by sequencing the V4 hypervariable region of bacterial 16S ribosomal RNA. Probiotic-treated larvae showed significant increases in every measured morphological parameter and in survival compared to the controls and AB-treated larvae, including TL, eye development, and swim bladder development before first feeding. Staining with DASPEI (2-(4-[dimethylamino]styryl)-N-ethylpyridinium iodide) produced fluorescence, revealing increased mitochondrial activity in the gastrointestinal tracts of probiotic-treated larvae and reflecting advancement of initial metabolic function. Probiotic-treated larvae showed accelerated yolk absorption, resulting in increased nutrient mobilization and growth. Microbial analyses revealed a greater concentration of bacteria in larvae in response to the probiotic treatment compared to the other two treatments. Species identified in all three treatments included Pseudomonas spp. and Aeromonas spp. (Proteobacteria). The second most diverse and abundant microbiome was seen in controls, whereas AB-treated larvae had the least diverse microbiome. All treatments revealed the presence of proteobacteria, but an AB-resistant pathogenic bacterium (Stenotrophomonas maltophilia) was identified in the AB group. These results reveal that the presence of LAB and other bacteria favorably influenced early larval growth, development, digestive function, and survival in Zebrafish even before the onset of feeding.

Evolutionary divergence of locomotion in two related vertebrate species.

Locomotion exists in diverse forms in nature; however, little is known about how closely related species with similar neuronal circuitry can evolve different navigational strategies to explore their environments. Here, we investigate this question by comparing divergent swimming pattern in larval Danionella cerebrum (DC) and zebrafish (ZF). We show that DC displays long continuous swimming events when compared with the short burst-and-glide swimming in ZF. We reveal that mesencephalic locomotion maintenance neurons in the midbrain are sufficient to cause this increased swimming. Moreover, we propose that the availability of dissolved oxygen and timing of swim bladder inflation drive the observed differences in the swim pattern. Our findings uncover the neural substrate underlying the evolutionary divergence of locomotion and its adaptation to their environmental constraints.

Active swimming and transport by currents observed in Japanese eels (Anguilla japonica) acoustically tracked in the western North Pacific

The mechanisms of oceanic animal migration remain enigmatic. Adult Japanese eels start their long-distance oceanic migration from coastal areas to breed near the West Mariana Ridge. We tracked acoustically tagged eels released in the Kuroshio Current (KC) area near Japan (five silver-phase eels, three of which had impaired swim bladders) and a tropical/subtropical (TS) area near/in the spawning area (two yellow-phase and three silver-phase eels). We analyzed their active swimming and transport by water currents. The strong flow of the KC dominated the eels’ movements in the north, and TS area; their swimming influenced their movements. In the KC area, greater distances were covered at night than during the day, because eels swam in shallower layers with strong currents at night. Three and one eel in the TS and KC area in the upper 400 m showed counterclockwise and clockwise movements around the time of solar culmination, respectively. The meta-analysis showed that eels released at middle latitudes (20°–34° N) generally swam southward through currents, whereas those released at low latitudes (12°–13° N) generally swam northward through currents. Our study suggests the influence of the surrounding current and a potential effect of solar cues on the movements of Japanese eels.

A solvent-dependent dual chemosensor for detecting Zn2+ and Hg2+ based on thiophene and thiourea functional groups by fluorescence turn-on

A new thiophene- and thiourea-based fluorescent chemosensor NTHC, N-(naphthalen-1-yl)-2-(thiophene-2-carbonyl)hydrazine-1-carbothioamide, was synthesized. NTHC can operate as a dual-functional chemosensor for selective sensing of Hg2+ and Zn2+ by fluorescent turn-on in different solvents, bis-tris buffer, and aqueous DMSO. According to the analysis of Job plot and ESI-mass, the complexation mode of NTHC to Zn2+ was determined to be a 1:1 ratio. The limits of detection of Hg2+ and Zn2+ turned out to be 4.92 μM and 3.17 μM, respectively. Interestingly, NTHC detected Hg2+via the mercury-promoted desulfurization reaction of thiourea to urea. Moreover, NTHC can be applied for the bioimaging of zinc in zebrafish. The bioimaging showed fluorescence in air bladder and eyes of zebrafish. The binding mechanisms of NTHC with the two ions were identified by Job plot analysis, ESI-mass, DFT calculations, and NMR titration.

Comparative transcriptome analysis between muscle and swim bladder reveals key genes regulating collagen deposition in zebrafish

Collagens are the most abundant extracellular matrix (ECM) proteins, which play important role in maintaining muscle texture of fish. Appropriate enhancement of tissue collagen deposition would improve quality of fish products. However, the regulatory mechanism of tissue collagen deposition remains poorly understood in fish. Here, we reported a comparative investigation on collagen deposition, transcriptional profile of collagen and their regulatory genes between muscle and swim bladder in zebrafish. Moreover, the function of key regulatory genes was investigated in vitro. Results indicated that collagen content in swim bladder was much higher than that in muscle. Transcriptome analysis identified 7351 differentially expressed genes and enrichment of ECM-related functional terms. The expression level of 26 collagen genes was significantly higher in swim bladder, including 5 of 8 highly-expressed genes (col1a1a, col1a2, etc.). Besides, most putative collagen regulatory genes (20/24) have higher expression level in swim bladder. Protein-protein interaction network analysis indicated that mmp2, p3h, ctgfa, serpinh1a have close interaction with col1 genes (col1a1a, col1a2). Over-expression of ctgfa and serpinh1a significantly promoted transcription of col1 genes and increased collagen I content in zebrafish fibroblast. It’s concluded that transcriptional signature of collagen genes varies between tissues and is differentially regulated by collagen regulators. Our data provides novel insights into the regulatory mechanism of tissue collagen metabolism and key molecular targets for regulating collagen deposition in fish during aquaculture practice.

The Use of Natural Collagen Obtained from Fish Waste in Hair Styling and Care.

Chemically speaking, polymers are multi-molecular compounds that have specific physicochemical properties. Hair cosmetics utilize their ability to create a protective film and make the cosmetic formulation more viscous, which facilitates its application. Natural polymers are encountered in nature, but, in hair cosmetics, artificially modified ones are more often used. Unfortunately, artificially modified polymers are characterized by high resistance to biological factors, which creates an ecological problem. Another reason for a search for natural polymers is their milder action when compared to synthetic ones. One of the new sources of obtaining collagen is the waste connective tissue materials of aquatic animals—skins, spines, dorsal chords and scales, and swim bladders. These raw materials are most often disposed of in landfills, processed into fish meal, or destined for food for animals. The conducted research was aimed at proving the action of natural collagen in hair cosmetics as a substitute for synthetic polymers. In the patients using collagen laminate, it is possible to notice the complete elimination of excessive sebum production, restoration of the correct pH value, and reduction in skin inflammations.

Natterin-like depletion by CRISPR/Cas9 impairs zebrafish (Danio rerio) embryonic development

BackgroundThe Natterin protein family was first discovered in the venom of the medically significant fish Thalassophryne nattereri, and over the last decade natterin-like genes have been identified in various organisms, notably performing immune-related functions. Previous findings support natterin-like genes as effector defense molecules able to activate multiprotein complexes driving the host innate immune response, notably due to the pore-forming function of the aerolysin superfamily members. Herein, employing a combination of the CRISPR/Cas9 depletion system, phenotype-based screening, and morphometric methods, we evaluated the role of one family member, LOC795232, in the embryonic development of zebrafish since it might be implicated in multiple roles and characterization of the null mutant is central for analysis of gene activity.ResultsMultiple sequence alignment revealed that the candidate natterin-like has the highest similarity to zebrafish aep1, a putative and better characterized fish-specific defense molecule from the same family. Compared to other species, zebrafish have many natterin-like copies. Whole-mount in situ hybridization confirmed the knockout and mutant embryos exhibited epiboly delay, growth retardation, yolk sac and heart edema, absent or diminished swim bladder, spinal defects, small eyes and head, heart dysfunction, and behavioral impairment. As previously demonstrated, ribonucleoproteins composed of Cas9 and duplex guide RNAs are effective at inducing mutations in the F0 zebrafish.ConclusionsThe considerably high natterin-like copies in zebrafish compared to other species might be due to the teleost-specific whole genome duplication and followed by subfunctionalization or neofunctionalization. In the present work, we described some of the natterin-like features in the zebrafish development and infer that natterin-like proteins potentially contribute to the embryonary development and immune response.

Peptides from the croceine croaker (Larimichthys crocea) swim bladder attenuate busulfan-induced oligoasthenospermia in mice

Context The swim bladder of the croceine croaker is believed to have a therapeutic effect on various diseases. However, there is no research about its effect on mammalian spermatogenesis. Objective We investigated the swim bladder peptides (SBPs) effect on busulfan-induced oligoasthenospermia in mice. Materials and methods We first extracted SBP from protein hydrolysate of the croceine croaker swim bladder, and then five groups of ICR male mice were randomly assigned: control, control + SBP 60 mg/kg, busulfan, busulfan + SBP 30 mg/kg and busulfan + SBP 60 mg/kg. Mice received bilateral intratesticular injections of busulfan to establish oligoasthenospermia model. After treatment with SBP for 4 weeks, testis and epididymis were collected from all mice for further analysis. Results After treatment with SBP 30–60 mg/kg for 4 weeks, epididymal sperm concentration and motility increased by 3.9–9.6- and 1.9–2.4-fold than those of oligoasthenospermia mice induced by busulfan. Meanwhile, histology showed that spermatogenic cells decreased, leading to increased lumen diameters and vacuolization in the busulfan group. These features were reversed by SBP treatment. RNA-sequencing analysis revealed that, compared with the busulfan group, Lin28b and Igf2bp1 expression related to germ cell proliferation, increased with a >1.5-fold change after SBP treatment. Additionally, PGK2 and Cfap69 mRNAs associated with sperm motility, also increased with a >1.5-fold change. Furthermore, these findings were validated by quantitative real-time PCR and Western blotting. Discussion and conclusions This is the first reported evidence for the therapeutic effect of SBP on oligoasthenospermia. SBP may be a promising drug for oligoasthenospermia in humans.