Ontogenetic change in the body length–mass relationship concomitant to the onset of vitellogenesis in female blackmouth catshark Galeus melastomus (Chondrichthyes: Scyliorhinidae)

The examination of the total length (L) vs. body mass (W) relationship in the blackmouth catshark from the southern Adriatic Sea showed the occurrence of two development phases or growth stanzas in females. The passage from the first stanza (L range: 22.8-37.4cm) to the following one (L range: 39.7-51.4cm) was marked by an inflection in the power equation correlating body mass to total length, occurring at about 38.6cm of length (change point). After the change point, growth became positively allometric. This catshark is a lecitotrophic oviparous continuous spawner, and follicles in different stages of development are simultaneously present in the ovary. The histological analysis of the ovary showed that the smallest vitellogenic follicles were about 2mm in diameter; the diameter of the largest observed oocyte was 18mm. The change point occurred slightly before the onset of vitellogenesis (smallest vitellogenic female L=41.0cm) and appeared to be related to the activation of the reproductive axis

Atresia of ovarian follicles in fishes, and implications and uses in aquaculture and fisheries

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

A ‘machine learning’ technique for discriminating captive-reared from wild Atlantic bluefin tuna, Thunnus thynnus (Osteichthyes: Scombridae), based on differential fin spine bone resorption

The Atlantic bluefin tuna (ABFT) fishery is regulated by the International Commission for the Conservation of Atlantic Tunas (ICCAT), which establishes the allowable annual yield and the minimum capture size, and allocates capture quotas to the Contracting Parties. Despite fishery monitoring, a considerable amount of captures escapes ICCAT control. In the Mediterranean Sea, the purse seine fishery supports ABFT farming, a capture-based aquaculture activity that involves catching fish from the wild and rearing them in sea cages for a few months. The first spine of the cranial dorsal fin undergoes a continuous bone remodeling process consisting in old bone (primary bone) resorption and new bone (secondary bone) apposition. A marked increase of spine bone resorption was shown in captive-reared ABFT with respect to wild specimens. In this paper, the Random Forest (RF), a Computer Aided Detection system, was applied to distinguish captive-reared from wild ABFT based on fish age, fish fork length, total surface of spine cross section, and surface of remodeled bone tissue in the spine cross section (sum of reabsorbed bone tissue and secondary cancellous bone). The RF system was also compared to the Logistic Regression method (LR). The percentages of properly classified animals, either wild or captive-reared, with respect to the overall number of animals, i.e. accuracy, was 95.3 ± 2.6% and 79.0 ± 5.1% for RF and LR, respectively. The percentages of the properly classified captive-reared specimens, i.e. sensitivity, were 93.5 ± 3.1% and 75.8 ± 5.3% for RF and LR, respectively. The percentages of the properly classified wild specimens was 96.7 ± 2.2% and 81.4 ± 4.9%, for RF and LR, respectively. The proposed technique appears to be a reliable investigation tool anytime the suspicion arises that illegally caught ABFT are sold as aquaculture products

Differential lectin binding patterns in the oviductal ampulla of the horse during oestrus

We investigated the oligosaccharide sequence of glycoconjugates, mainly sialoglycoconjugates, in the horse oviductal ampulla during oestrus by means of lectin and pre-lectin methods such as the KOH-neuraminidase procedure to remove sialic acid residues and incubation with N-glycosidase F to cleave N-linked glycans. Ciliated cells displayed N-linked oligosaccharides throughout the cytoplasm. The cilia glycocalyx expressed both N- and O-linked (mucin-type) oligosaccharides, both showing a high variety of terminal sequences. In the most non-ciliated cells, the whole cytoplasm contained N-linked oligosaccharides with terminal αGal as well as mucin-type glycans with terminal Forssman pentasaccharides. In a few scattered non-ciliated cells, the whole cytoplasm displayed sialylated N-linked oligosaccharides with terminal Neu5Ac-GalNAc and O-linked glycans terminating with neutral and/or αGalNAc, Neu5Acα2,6Gal/ GalNAc, Neu5AcGalβ1,3GalNAc. Supra-nuclear granules, probably Golgi zones, of non-ciliated cells showed mainly O-linked glycans rich in sialic acid residues. The luminal surface of non-ciliated cells showed N-linked oligosaccharides, containing terminal/internal αMan/αGlc, βGlcNAc and terminal αGal, as well as mucin-type oligosaccharides terminating with a large variety of either neutral saccharides or sialylated sequences. Apical protrusions containing O-linked oligosaccharides with terminal Forssman pentasaccharide, Neu5Ac-Galβ1,4GlcNAc, Neu5Ac-GalNAc were seen in nonciliated cells scattered along the epithelium. These findings show the presence of sialoglycoconjugates in the oviductal ampulla epithelium of the mare and the existence of different lectin binding profiles between ciliated and non-ciliated (secretory) cells, as well as the presence of non-ciliated cell sub-types which might determine functional differences along the ampullary epithelium of mare oviduct

Male germ cell proliferation and apoptosis in sexually immature meagre Argyrosomus regius (Asso, 1801) treated with recombinant follicle stimulating hormone

The meagre Argyrosomus regius (Asso, 1801) is a marine fish species that has an increasing aquaculture production in Europe. Lowering the age at maturity of hatchery-produced juveniles would support meagre aquaculture by reducing time between generations in selective breeding programs and reducing industrial costs for broodstock maintenance. The aim of this work was to assess the effects of a treatment with recombinant follicle stimulating hormone (rFsh), produced in ovarian cells of Chinese hamsters, on male germ cell proliferation and apoptosis in sexually immature meagre. The rFsh-treated fish had higher gonadosomatic index, larger seminiferous tubules, more abundant luminal spermatozoa, a lower density of anti-PCNA positive single A spermatogonia, a higher density of anti-PCNA positive spermatocysts and a lower incidence of germ cell apoptosis than control groups. The present study demonstrated the effectiveness of the produced rFsh in stimulating testis development and spermatogenesis in pre-pubertal meagre. Moreover, the rFsh treatment proved to be highly efficient in removing the apoptotic block of spermatogenesis observed in juvenile meagre, allowing spermatogonial survival and progress towards meiosis. The administration of rFsh did not stimulate spermatogonial self-renewal, a process whose control still needs to be elucidated.info:eu-repo/semantics/publishedVersio

Further observations on the sensitive innervation of some bird’s proctodeum

The AA. studied the autonomic and sensitive somatic innervation of some female bird's proctodeum, through the properly modified Ruffini's gold chloride method. The vegetative component was constituted by ganglion cells of different size, isolated or grouped to form ganglia, found along the course of nerve trunks or in the concurrent point of different nerve bundles. The sensitive somatic innervation was represented by free and encapsulated endings differently distributed in the thickness of the wall. The former were composed of thin networks, while the latter, located more frequently in the muscular tunica and in the subadventitial connective, were composed of encapsulated receptors classified as Pacini, Pacini-like and Herbst corpuscles. The morphology of these receptors was described and hypotheses were brought up about their probable functional role. The AA. also found, even if very rarely, helicoidal collagen fibres around nerve fascicles

Distribution of sialoglycoconjugates in the oviductal isthmus of the horse during anoestrus, oestrus and pregnancy: a lectin histochemistry study

The distribution of sialic acid residues as well as other glycosidic sugars has been investigated in the horse oviductal isthmus during anoestrus, oestrus and pregnancy by means of lectin and pre-lectin methods. Ciliated cells and non-ciliated (secretory) cells exhibited different lectin binding profiles that were found to change during the investigated stages. Ciliated cells did not show any reactivity in the basal cytoplasm, while the supra-nuclear cytoplasm displayed a few of oligosaccharides with terminal and internal amannose (Man) and/or aglucose (Glc) during oestrus and pregnancy and a moderate presence of oligosaccharides terminating in afucose (Fuc) during oestrus; cilia exhibited a more complex glycoconjugate pattern for the presence of oligosaccharides terminating in N-acetylgalactosamine (GalNAc), GalNAca1,3 GalNAca1,3galactose(Gal)b1,4Galb1,4N-acetylglucosamine( GlcNAc), Fuc, sialic acid (Neu5Ac)-aGalNAc belonging or not to the GalNAca1,3GalNAca1,3 Galb1,4 Galb1, 4GlcNAc sequence, and.aGalNAc and Neu5Aca 2,6Gal/GalNAc increased during oestrus. Cilia displayed terminal Galb1,3 GalNAc in pregnancy, terminal aGal in anoestrus and pregnancy and terminal or internal D-GlcNAc during anoestrus and pregnancy, respectively. The whole cytoplasm of non-ciliated cells showed oligosaccharides terminating with aGalNAc, Neu5Aca2,6Gal/GalNAc, Neu5Ac GalNAca 1,3GalNAca1,3Galb1,4Galb1,4GlcNAc during the investigated stages, as well as GlcNAc in anoestrus and pregnancy. The supra-nuclear zone of non-ciliated cells exhibited oligosaccharides with terminal Galb1,4GlcNAc and internal Man during oestrus and pregnancy as well as terminal aGal and Fuc in oestrus and Neu5Ac-Galb1,3GalNAc in pregnancy. The luminal surface of non-ciliated cells showed glycans terminating with aGalNAc and/or Neu5Ac GalNAca1,3 GalNAca1,3Galb1,4Galb1,4GlcNAc in all specimens, oligosaccharides with terminal Galb1,4GlcNAc and internal Man during oestrus and pregnancy, Neu5Ac a2,6Gal/GalNAc in anoestrus and oestrus, and glycans terminating with Galb1,3GalNAc, Neu5A aca2,3 Galb1, 4GlcNac, Neu5ac- Galb1,3GalNAc, Neu5Ac-Galb1,4 GlcNAc in pregnancy. These findings show the presence of sialoglycoconjugates in the oviductal isthmus of the mare as well as the existence of great modifications in the glycoconjugates linked to different physiological conditions

Brain morphology and immunohistochemical localization of the gonadotropin-releasing hormone in the bluefin tuna, <i>Thunnus thynnus</i>

The present study was focused on the morphology of the diencephalic nuclei (likely involved in reproductive functions) as well as on the distribution of GnRH (gonadotropin-releasing hormone) in the rhinencephalon, telencephalon and the diencephalon of the brain of bluefin tuna (Thunnus thynnus) by means of immunohistochemistry. Bluefin tuna has an encephalization quotient (QE) similar to that of other large pelagic fish. Its brain exhibits well-developed optic tecta and corpus cerebelli. The diencephalic neuron cell bodies involved in reproductive functions are grouped in two main nuclei: the nucleus preopticus-periventricularis and the nucleus lateralis tuberis. The nucleus preopticus-periventricularis consists of the nucleus periventricularis and the nucleus preopticus consisting of a few sparse multipolar neurons in the rostral part and numerous cells closely packed and arranged in several layers in its aboral part. The nucleus lateralis tuberis is located in the ventral-lateral area of the diencephalon and is made up of a number of large multipolar neurones. Four different polyclonal primary antibodies against salmon (s)GnRH, chicken (c)GnRH-II (cGnRH-II 675, cGnRH-II 6) and sea bream (sb)GnRH were employed in the immunohistochemical experiments. No immunoreactive structures were found with anti sbGnRH serum. sGnRH and cGnRH-II antisera revealed immunoreactivity in the perikarya of the olfactory bulbs, preopticus-periventricular nucleus, oculomotor nucleus and midbrain tegmentum. The nucleus lateralis tuberis showed immunostaining only with anti-sGnRH serum. Nerve fibres immunoreactive to cGnRH and sGnRH sera were found in the olfactory bulbs, olfactory nerve and neurohypophysis. The significance of the distribution of the GnRHimmunoreactive neuronal structures is discussed

The observed oogenesis impairment in greater amberjack Seriola dumerili (Risso, 1810) reared in captivity is not related to an insufficient liver transcription or oocyte uptake of vitellogenin

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

Rearing in captivity affects spermatogenesis and sperm quality in greater amberjack, Seriola dumerili (Risso, 1810)

The greater amberjack, Seriola dumerili (Risso, 1810), is a promising candidate for the diversification of European aquaculture production, but inconsistent reproduction in captivity prevents commercial production. Recent studies showed that greater amberjack confined in sea cages exhibited scarce gonad development and early interruption of gametogenic activity during the reproductive season. The aim of the present study was to improve our understanding of the observed impairment of spermatogenesis. Adult wild and captive-reared males were sampled during 3 different phases of the reproductive cycle: early gametogenesis (EARLY; late April to early May), advanced gametogenesis (ADVANCED; late May to early June), and spawning (SPAWNING; late June to July). Spermatogonial stem cells and proliferating germ cells were identified through the immunohistochemical localization of Pou5f1 and proliferating cell nuclear antigen, respectively. Apoptotic germ cells were identified throughout the terminal deoxynucleotidyl transferase-mediated 2â -deoxyuridine 5â -triphosphate nick end labeling method. Sperm quality of captive-reared fish was evaluated using computer-assisted sperm analysis. Captive-reared males exhibited seminiferous lobules of a smaller diameter, a precocious and progressive decrease of spermatogonial mitosis, and a high level of apoptosis at the beginning of the reproductive season, concomitant with a many-fold higher 17β-estradiol plasma concentration. The motile spermatozoa percentage of captive greater amberjack was lower than in other teleosts, and a drastic decrease of spermatozoa motility duration, velocity, and ATP content occurred along the reproductive season. An abnormal increase of sperm concentration as well as an increase of dead spermatozoa occurred during the SPAWNING phase, probably because of lack of sperm hydration and ejaculation and consequent sperm ageing. The present study demonstrates the extreme susceptibility of greater amberjack to rearing stress and underscores the need for improvement of the rearing and handling procedures to ameliorate gametogenesis dysfunctions in commercial aquaculture production