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Simple Summary: Carps include some of the most widely farmed fresh water species. In the present study, the incidence of skeletal malformations in the fingerlings of four carp species reared in semi-intensive conditions in Albania was assessed. The investigated species were the common carp (Cyprinus carpio), silver carp (Hypophthalmichthys molitrix), grass carp (Ctenopharyngodon idella) and bighead carp (Hypophthalmichthys nobilis). The incidence of skeletal malformations and body growth were much higher in the herbivorous silver carp, grass carp and bighead carp than in the omnivorous common carp. We hypothesized that (i) the feeding protocol, which included ingredients of animal origin, may have caused an abnormal increase in the body growth rate associated with an increase in skeletal malformations in the herbivorous carp species; (ii) more efficient broodstock management may help increase egg quality and reduce skeletal malformations. Cyprinids include some of the most widely farmed freshwater species. The aim of this study was to assess the incidence of skeletal malformations in carp species reared in semi-intensive systems in Albania: common carp (Cyprinus carpio), silver carp (Hypophthalmichthys molitrix), grass carp (Ctenopharyngodon idella) and bighead carp (Hypophthalmichthys nobilis). The common carp fingerlings had a mean total length of 28.9 ± 5.0 mm; the frequencies of individuals with at least one anomaly and at least one severe anomaly were 79.2% and 43.4%, respectively. The silver carp juveniles had a mean total length of 21.6 ± 2.1 mm; the frequencies of individuals with at least one anomaly and one severe anomaly were 93.1% and 57.5%, respectively. The grass carp fry had a mean total length of 33.5 ± 2.6 mm; all the analyzed specimens showed almost one anomaly and 86.4% showed at least one severe anomaly. The bighead carp juveniles had a mean total length of 34.4 ± 5.7 mm; the frequencies of individuals with at least one anomaly and at least one severe anomaly were 95.0% and 62.5%, respectively. The development of a more suitable feeding protocol for herbivorous species and the setting up of more efficient broodstock management protocols are suggested to reduce the high incidence of skeletal malformations. [ABSTRACT FROM AUTHOR]

Simple Summary: The meagre (scientific name: Argyrosomus regius) is a fish species inhabiting the Mediterranean Sea and the eastern Atlantic Ocean. Consumer appreciation and good market quotations induced the aquaculture industry to invest in its domestication. However, when reared in tanks, meagre males produce milt of low quality and quantity, and females do not finalise oogenesis and do not spawn spontaneously. The reproductive dysfunctions affecting meagre reared in tanks, can be alleviated through the use of hormone administration or through the association of hormone treatments with photo-thermal control. In this study, the reproductive maturation of meagre, reared in sea cages under routine farming condition, was assessed. It was observed that female and male meagre produced in captivity (hatchery), transferred as juveniles to sea cages located in the Gulf of Taranto (Italy), and reared until sexual maturity under routine commercial conditions, are able to produce and release gametes spontaneously. Meagre reproduction, under routine farming conditions, may represent an opportunity for the expansion of meagre EU aquaculture production; this actually relies on limited amounts of fingerlings, produced by few hatcheries. The meagre Argyrosomus regius (Asso, 1801) is a promising aquaculture species that shows reproductive dysfunctions when reared in tanks. The aim of this study was to assess the capacity of meagre, reared in cages under routine farming conditions, to mature gonads and reproduce spontaneously. Meagre adults, reared in a fish farm located in the Gulf of Taranto (Italy), were sampled from March to July 2021. The gonadosomatic index and sex steroid plasma concentrations increased from March–April to June, and then decreased in July. In March–April, most of the females showed perinucleolar or cortical alveoli oocytes as the most advanced stages in the ovaries, and most of the males had testes at early spermatogenesis stage. In June, most of the sampled females had oocytes at late vitellogenesis or early post-vitellogenesis stages, and males had seminiferous tubules filled with spermatozoa. In July, most of the females had signs of previous spawning, and males showed scarce amounts of luminal spermatozoa. The present study demonstrated the capacity of meagre, reared in sea cages under commercial conditions, to carry out gametogenesis and spontaneously release gametes. Meagre reproduction, under routine farming conditions, may represent an opportunity for the expansion of meagre aquaculture production. [ABSTRACT FROM AUTHOR]

Simple Summary: Spermatogenesis is a complex process through which male gametes, spermatozoa, are produced starting from stem germ cells called spermatogonia. The existing information on cat spermatogenesis is limited and somewhat contradictory. In fact, although this species is considered a long-day breeder with a reproduction period starting when the day length increases and ending in late autumn, spermatogenesis and sperm production occur throughout the year. In order to assess whether cat spermatogenesis is modulated according to a season pattern, we analyzed testes taken from feral cats orchiectomized during reproductive (February–July) and non-reproductive (November and December) periods. The results of the analyses carried out in the present study showed that spermatogonial proliferation was more intense during the reproductive period and germ cell death via apoptosis (a programmed form of cell death) increased during the non-reproductive period. Our results confirm the hypothesis that cat spermatogenesis is seasonally modulated through changes of germ cell proliferation and apoptosis, according to a common paradigm of seasonally breeding species. The domestic cat (Felis catus) is a seasonal-breeding species whose reproductive period starts when the day length increases. Since the existing information on cat spermatogenesis is limited and somewhat contradictory, in the present study, germ cell proliferation and apoptosis in feral adult tomcats orchiectomized during reproductive (reproductive group, RG; February–July) and non-reproductive (non-reproductive group, NRG; November and December) seasons were compared. Cross-sections taken from the middle third of the left testis were chemically fixed and embedded in paraffin wax. Histological sections were processed for the immunohistochemical detection of proliferating germ cells (PCNA) and for the identification of apoptotic cells (TUNEL method). The percentage of PCNA-positive spermatogonia was higher in the RG than in the NRG. On the contrary, germ cell apoptosis was higher in the NRG than in the RG. Our results confirm that cat spermatogenesis is modulated on a seasonal basis and suggests that spermatogenesis control involves changes in germ cell proliferation and apoptosis according to a common paradigm of seasonally breeding species. [ABSTRACT FROM AUTHOR]

This method generates a negative image of fish skeleton, and it is also applicable to alive fish, provided that suitable X-ray equipment (X-ray generator and detector) is available in the farming facility. Larval performance and skeletal deformities in farmed gilthead sea bream (Sparus aurata) fed with graded levels of Vitamin A enriched rotifers (Brachionus plicatilis). Keywords: juvenile fish; microradiography; sekeletal anomalies EN juvenile fish microradiography sekeletal anomalies 1237 1241 5 07/15/22 20220801 NES 220801 INTRODUCTION As for any industrial sector, the aquaculture industry needs to minimize production costs to increase business profit and competitiveness. Skeletal descriptors and quality assessment in larvae and post-larvae of wild-caught and hatchery-reared gilthead sea bream (Sparus aurata L. 1758). [Extracted from the article]

Atresia of ovarian follicles, that is the degenerative process of germ cells and their associated somatic cells, is a complex process involving apoptosis, autophagy and heterophagy. Follicular atresia is a normal component of fish oogenesis and it is observed throughout the ovarian cycle, although it is more frequent in regressing ovaries during the postspawning period. An increased occurrence of follicular atresia above physiological rates reduces fish fecundity and even causes reproductive failure in both wild and captive‐reared fish stocks, and hence, this phenomenon has a wide range of implications in applied sciences such as fisheries and aquaculture. The present article reviews the available literature on both basic and applied traits of oocyte loss by atresia, including its morpho‐physiological aspects and factors that cause a supraphysiological increase of follicular atresia. Finally, the review presents the use of early follicular atresia identification in the selection process of induced spawning in aquaculture and the implications of follicular atresia in fisheries management. [ABSTRACT FROM AUTHOR]

The family Carangidae contains several species of aquaculture interest, including the amberjacks, yellowtails and trevallies. Among them, the greater amberjack (Seriola dumerili), the Japanese amberjack or yellowtail (Seriola quinqueradiata) and the yellowtail kingfish (Seriola lalandi) are considered the species with the highest potential for commercial aquaculture. Understanding the reproductive physiology–biology, spawning kinetics and production characteristics in captivity are of utmost importance for the domestication of any animal, and developing broodstock management methods and therapies to optimize egg production and overcome potential reproductive dysfunctions are essential. The present article reviews the available literature on the reproductive biology of the Carangidae species of interest for the aquaculture industry, both in the wild and under farming conditions. The reproductive traits of wild and farmed fish, whenever available, were compared in order to improve the understanding of the reproductive dysfunctions occurring in captivity. Finally, the hormonal maturation and spawning induction protocols examined so far to ameliorate the reproductive dysfunctions and obtain fertile gametes are summarized, and their effectiveness in the different rearing conditions is discussed. [ABSTRACT FROM AUTHOR]

The greater amberjack Seriola dumerili is a new aquaculture fish that may display reproductive dysfunctions. During extensive follicular atresia, which is a common reproductive dysfunction in females during vitellogenesis, part of the reabsorbed yolk returns to the liver to be metabolized and recycled. Melanomacrophage centres (MMCs) are aggregates of macrophage‐like cells that play a role in the destruction, detoxification and recycling of endogenous and exogenous materials, and have been associated with systemic stress. Wild and captive‐reared greater amberjack were sampled in the Mediterranean Sea during two different phases of the reproductive cycle. The liver of reproductively dysfunctional captive‐reared females sampled during the spawning season showed a high density of both MMCs and apoptotic cells. A weak liver anti‐cytochrome P450 monooxygenase 1A immunoreactivity was observed, suggesting that the examined fish were not exposed to environmental pollutants. We propose that the observed increase in MMCs and apoptosis in captive‐reared fish was related to the hepatic overload associated to the metabolism of yolk proteins reabsorbed during extensive follicular atresia. Since follicular atresia is a frequent physiological and pathological event in teleosts, we suggest that the reproductive state should be always assessed when MMCs are used as markers of exposure to stress or pollutants. [ABSTRACT FROM AUTHOR]

The age of sexual maturity of the Atlantic bluefin tuna (Thunnus thynnus; ABFT) is a reference point for stock assessment and management. The International Commission for the Conservation of Atlantic Tunas (ICCAT) recognizes a western and an eastern Atlantic ABFT stock, based on the assumptions of separate, exclusive spawning grounds, i.e., the northern Gulf of Mexico and the Mediterranean Sea, with different ages of sexual maturity, 8–12 years vs 3–5 years, respectively. Multiple line of evidences indicate that spawning is not restricted to the Gulf of Mexico and the Mediterranean Sea, and reconsideration of historical documents, as well as results from recent studies, indicate that sexual maturation schedules of the two proposed stocks are similar (3–5 years). The present review of classical and recent literature suggests that ABFT have more complex reproductive behavior than previously considered: on eastern spawning grounds 50% of ABFT females reproduce at 3 years of age and 100% are sexually mature at 5 years of age. In the western management area, younger adults (age ≥ 5 years) and some larger adults apparently spawn in the northwest Atlantic Ocean across the Slope and Caribbean Seas, whereas the Gulf of Mexico spawners are mostly large adults (age ≥ 8 years). [ABSTRACT FROM AUTHOR]

The goal of the present study was to verify the suitability of using melanomacrophage centres (MMCs) as response biomarkers of marine pollution in European anchovy, which are short-lived, migratory, small pelagic fish. This suitability was verified by analysing the MMC density and cytochrome P450 monooxygenase 1A (CYP1A) expression in livers of anchovies from four areas of southern Italy. Age 2 anchovies sampled from three areas exposed to pollutants of industrial/agricultural origin (Gulf of Gela, Mazara del Vallo and Gulf of Naples) showed liver areas occupied by MMCs and numbers of MMCs that were significantly higher than those in the anchovies from Pozzallo, which is a marine area not subjected to any source of pollution. Anti-CYP1A immunoreactivity was observed in the hepatocytes of all specimens sampled from the Gulf of Gela. These findings suggest the utility of liver MMCs as biomarkers of exposure to pollutants in this small pelagic fish. [ABSTRACT FROM AUTHOR]

The greater amberjack Seriola dumerili is an excellent candidate for the Mediterranean aquaculture, due to its large body size and high growth rate, as well as its high flesh quality and commercial value worldwide. For its successful incorporation in the aquaculture industry, an in-depth understanding of the reproductive function of the species under rearing conditions is necessary, since completion of oogenesis in captivity is currently a bottleneck for the commercial production of the species. Liver and ovary samples from wild and captive-reared greater amberjack females were collected at three different phases of the reproductive cycle: early gametogenesis (EARLY, late April-early May), advanced gametogenesis (ADVANCED, late May-early June) and spawning (SPAWNING, late June-July). The cDNAs of three vitellogenins (VtgA, VtgB and VtgC) were partially sequenced and a qRT-PCR for their expression was used to compare ovarian maturity stage and liver vitellogenin transcript levels between wild and captive-reared individuals. An extensive atresia of late vitellogenic follicles, which prevented any further oocyte development and spawning was observed in captive-reared individuals during the ADVANCED phase. The expression levels of the three vitellogenins, as well as the amount of yolk globules in vitellogenic oocytes, did not differ significantly between captive-reared and wild females, indicating that the observed oogenesis impairment in greater amberjack reared in captivity was not related to an insufficient liver synthesis or a reduced oocyte uptake of vitellogenin. [ABSTRACT FROM AUTHOR]

The greater amberjack Seriola dumerili is a large teleost fish with rapid growth and excellent flesh quality, whose domestication represents an ambitious challenge for aquaculture. The occurrence of reproductive dysfunctions in greater amberjack reared in captivity was investigated by comparing reproductive development of wild and captive-reared individuals. Wild and captive-reared breeders were sampled in the Mediterranean Sea during three different phases of the reproductive cycle: early gametogenesis (EARLY, late April-early May), advanced gametogenesis (ADVANCED, late May-early June) and spawning (SPAWNING, late June-July). Fish reproductive state was evaluated using the gonado-somatic index (GSI), histological analysis of the gonads and determination of sex steroid levels in the plasma, and correlated with leptin expression in the liver and gonad biochemical composition. The GSI and sex steroid levels were lower in captive-reared than in wild fish. During the ADVANCED period, when the wild greater amberjack breeders were already in spawning condition, ovaries of captive-reared breeders showed extensive atresia of late vitellogenic oocytes and spermatogenic activity ceased in the testes of half of the examined males. During the SPAWNING period, all captive-reared fish had regressed gonads, while wild breeders still displayed reproductive activity. Liver leptin expression and gonad proximate composition of wild and captive greater amberjack were similar. However, the gonads of captive-reared fish showed different total polar lipid contents, as well as specific lipid classes and fatty acid profiles with respect to wild individuals. This study underlines the need for an improvement in rearing technology for this species, which should include minimum handling during the reproductive season and the formulation of a specific diet to overcome the observed gonadal decrements of phospholipids, DHA (22:6n-3) and ARA (20:4n-6), compared to wild breeders. [ABSTRACT FROM AUTHOR]

The article focuses on a study of male germ cell proliferation and apoptosis of captive-reared Atlantic bluefin tuna (ABFT) thunnus thynnus during its reproductive cycle. Topics discussed include increase of germ cell apoptosis when spermatogenesis occurred from April to May, temporal overlapping between spermatogenesis in wild and captive ABFT, and gonadotropins and steroid hormones in mammals as a survival factor that prevents germ cell apoptosis.

Highlights: [•] Apoptosis and tumor necrosis factor expression determined in bluefin tuna liver. [•] High apoptosis density found in juvenile bluefin tuna from the northern Adriatic. [•] High expression of tumor necrosis factor-2 expression found in the same specimens. [•] High apoptosis and TNF2 expression possibly related to environmental pollutants. [Copyright &y& Elsevier]

A rapid, one-step agglutination assay has been developed, based on latex particles sensitized with antibodies against vitellogenin (Vtg), aimed at Atlantic bluefin tuna, Thunnus thynnus (Linnaeus) (ABFT), gender identification. The egg-yolk precursor protein Vtg was used as a gender marker for the assay as it is a female-specific protein synthesized during reproductive maturation. The presence of Vtg in the plasma was revealed in 60–120 s through an agglutination reaction by mixing small volumes of ABFT plasma and an anti-Vtg antibody-latex suspension on a microscope slide. The effectiveness of the present test was restricted to the months of May and June, concomitant with high circulating Vtg levels. Because of its rapidity and ease of performance in the field, the present gender identification assay could be useful for broodstock management in the aquaculture industry as well as in tagging studies on wild populations. [ABSTRACT FROM AUTHOR]

Simple Summary: The meagre, Argyrosomus regius, is a commercial fish species of which aquaculture production is limited due to technological bottlenecks such as inconstant reproduction in captivity. In addition, there are only a few broodstocks in European farms, which rises the problem of limited genetic variability of the cultured meagre population. The development of germ cell xenotransplantation technology might increase aquaculture production through the production of fertile meagre gametes in a host species for which farming technology is well established. Spermatogonial stem cells have the capacity to proliferate and to proceed through the spermatogenesis process, eventually giving rise to mature spermatozoa. In the present study, meagre spermatogonial stem germ cells were identified, isolated, cultured in vitro, and cryopreserved. Isolated spermatogonial stem cells proliferated, maintained their stem properties in culture, and were still viable after cryopreservation and thawing. This work represents a first step towards the development of a xenotransplantation technology that might facilitate the production of this valuable species in captivity. The meagre, Argyrosomus regius, is a valued fish species of which aquaculture production might be supported by the development of a stem germ cell xenotransplantation technology. Meagre males were sampled at a fish farm in the Ionian Sea (Italy) at the beginning and end of the reproductive season. Small and large Type A undifferentiated spermatogonia were histologically identified in the germinal epithelium. Among the tested stemness markers, anti-oct4 and anti-vasa antibodies labeled cells likely corresponding to the small single Type A spermatogonia; no labeling was obtained with anti-GFRA1 and anti-Nanos2 antibodies. Two types of single A spermatogonia were purified via density gradient centrifugation of enzymatically digested testes. Testes from fish in active spermatogenesis resulted in a more efficient spermatogonial stem cell (SSC) yield. After cell seeding, meagre SSCs showed active proliferation from Day 7 to Day 21 and were cultured up to Day 41. After cryopreservation in dimethyl-sulfoxide-based medium, cell viability was 28.5%. In conclusion, these results indicated that meagre SSCs could be isolated, characterized, cultured in vitro, successfully cryopreserved, and used after thawing. This is a first step towards the development of a xenotransplantation technology that might facilitate the reproduction of this valuable species in captivity. [ABSTRACT FROM AUTHOR]