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At least 19 recordsLinked to original sources
PubMed2026

ScRNA-seq analysis reveals the effects of nitrite stress on the endocrine system of the eyestalk in Litopenaeus vannamei.

Nitrite is a harmful substance generated in Litopenaeus vannamei farming systems, largely originating from the inadequate breakdown of surplus feed and shrimp feces. Its accumulation in the water can affect the growth and physiological functions of shrimp, damage the immune system, and even cause mass mortality, thus becoming a key environmental factor restricting the green development of the industry. Under nitrite stress, the eyestalk, as an important neuroendocrine regulatory center in crustaceans, participates in the stress adaptation of the organism and exerts a protective effect by regulating energy metabolism and immune function. However, the molecular regulatory mechanism of the eyestalk in response to nitrite stress remains unclear. In this study, single-cell RNA sequencing (scRNA-seq) technology was used to analyze the heterogeneity of eyestalk cells in L. vannamei under nitrite stress. A total of 18, 394 high-quality cells were obtained, and six major cell subpopulations, including Neurosecretory cell, Motor neuron, Sensory neuron, Interneuron, Neurogliocyte, and Support cell, were identified. Differential expression analysis identified 839 differentially expressed genes, and different cell types showed distinct specific responses to nitrite stress. Functional enrichment analysis indicated that pathways such as glycolysis, oxidative phosphorylation, ribosome function, and endoplasmic reticulum protein processing were significantly activated, while signal transduction and DNA repair-related pathways were inhibited. Further analysis revealed that nitrite stress could induce mitochondrial function changes and trigger oxidative stress, thereby affecting the neuroendocrine system function of the eyestalk. This study provided insights into transcriptomic responses of the eyestalk to nitrite stress at the single-cell level, laying a theoretical foundation for the management of aquaculture environments.

Animals↗
PubMed1978

Structural re-evaluation of the neurosecretory system in the crayfish eyestalk.

The topography of the neurosecretory system in the decapod eyestalk has not been precisely delineated with light microscopy. Cobalt iontophoresis and electron microscopy have proved useful in clarifying the microstructure of this system. The sinus gland (sg) of the crayfish eyestalk consists of aggregated axon terminals which end at or near the blood space. Iontophoresing cobalt back through the cut base of the sinus glands reveals proximal cell bodies in the eyestalk only in the X organ (Xo) region. Electron microscopy demonstrates that axons from about 115 neurosecretory cell bodies in the Xo form the Xo-sg tract. Intermingled with these Xo somata are smaller non-neurosecretory cell bodies which do not send axons into the sinus gland. One of these exhibits catecholamine fluorescence. Backfilling also reveals a second group of fibres which run from the brain along the optic tract and into the sinus gland. These brain-sg fibres are smaller in diameter than Xo-sg axons and lack neurosecretory vesicles. From these fibres collaterals extend into the eyestalk neuropil, especially in the proximity of the visual elements. The possible function of these non-neurosecretory processes within the sinus gland is discussed.

Animals↗
PubMed1976

[Cytochemical and ultrastructural study of oocyte development of the crab Eriocheir sinensis. II. Oogenesis after removal of the eyestalk].

The effect produced by an eyestalk removal have been studied on Eriocheir females at different physiological stages. In juvenile and prepuberal crabs, the operation induces an important rise of the oocyte diameter. Only a few variations are observed in puberal females oocytes. Cytological changes are found at first at the nucleolar level. The granular area increases and the nucleolar vacuoles volume decreases. Then the granules (precursor material to endogenous yolk) disappear in the reticulum cisternae. At this time, the endogenous yolk seems essentially elaborated within yolk lobules. The envelope of these lobules is enhanced by ribosomes. In juvenile females (oocytes initially in previtellogenesis) exogenous yolk does not appear. Nevertheless in prepuberal females, following eyestalks deprivation, the oocytes, initially at the endogenous vitellogenesis stage, quickly reach the vitellogenesis second stage. In such oocytes, the microvilli development and pinocytose vesicles number are greater than normally. Cytochemical tests reactions do not demonstrate differences in the yolk material (endogenous and exogenous) nature from experimented oocytes and controls. In juvenile and prepuberal oocytes, the multivesicular bodies and lysosomes proliferation, the increase in glycogen and lipids amount express a metabolic disturbance resulting from an acceleration of growth processes. However in eyestalk-less prepuberal females no difference with the control oocytes was noticed.

Animals↗
PubMed2026

Divergent responses of the gill, hepatopancreas, and eyestalk to acute alkalinity stress in Penaeus vannamei: Osmoregulatory compromise, metabolic trade-off, and endocrine disruption.

The expansion of aquaculture into inland saline-alkali waters is constrained by high carbonate alkalinity (CA), a severe environmental stressor for crustaceans. However, the systemic molecular mechanisms underlying its lethal toxicity remain poorly understood. In this study, we employed a comparative transcriptomic approach to investigate the tissue-specific responses of Pacific white shrimp, Penaeus vannamei, under acute lethal stress (48 h-LC50). We focused on three functionally distinct organs: the gill, hepatopancreas, and eyestalk. The results revealed a systemic but highly tissue-specific transcriptomic response. The gill, as the primary interface, exhibited severe structural impairment and critical failure of osmoregulation, highlighted by the significant downregulation of delta-1-pyrroline-5-carboxylate synthetase (P5CS). In contrast, the hepatopancreas initiates a profound metabolic trade-off, sacrificing growth-related pathways to bolster a robust antioxidant defense system, as evidenced by the activation of sulfur metabolism and high protein turnover. The eyestalk displayed a striking disconnect between hyperactivated stress signaling pathways (e.g., mTOR/FoxO) and the collapse of its protein secretory machinery, marked by the suppression of the ER translocon component Sec61. Collectively, our findings suggest that lethal alkalinity toxicity in P. vannamei results from systemic collapse driven by a complex interplay of osmoregulatory failure, metabolic trade-offs, and endocrine disruption. This study provides a comprehensive molecular snapshot of an organism at its physiological limit, offering novel insights into the adaptive strategies and ultimate tolerance boundaries of crustaceans in extreme environments.

Animals↗
PubMed1975

Histochemical observations on the occurrence of glycolytic and pentose phosphate cycle enzymes in the hepatopancreas and their possible relation to eyestalk factor(s) in the crab Scylla serrata (Forskal).

Histochemical studies were carried out on some of the glycolytic enzymes viz. phosphorylase, aldose, alpha-glycerophosphate dehydrogenase (alpha-GPDH) and lactic dehydrogenase (LDH) and a key enzyme of the pentose phosphatase cycle, glucose-6-phosphate dehydrogenase (G-6-PDH), in the hepatopancreas of Scylla serrata (Forskal). 1. Weak activities of phosphorylase and aldolase and strong-activities of alpha-GPDH and LDH were noticed mainly in the brush border of the tubules and R-cell cytoplasm. A trace activity of G-6-PDH was noticed in the brush border. 2. Bilateral eyestalk removal results in inhibition of both phosphorylase and aldolase. However, enhanced activities of alpha-GPDH and LDH were noticeable 4 h after the operation. The G-6-PDH activity remained unaltered till 24 h. 3. Injection of eyestalk extract into both intact and destalked crabs activated all the enzymes.

Animals↗
PubMed1979

Immunocytochemical identification of hyperglycemic hormone-producing cells in the eyestalk of Carcinus maenas.

Antiserum raised in rabbits against extracts of sinus glands from Carcinus annd shown by several criteria to contain antibodies directed against the neurosecretory hyperglycemic hormone was used to locate the hormone-producing perikarya in the optic ganglia. By means of the double antibody fluorescence technique, selective staining of the large neurosecretory perikarya of the medulla terminalis ganglionic X-organ (MTGXO) and their axons is obtained. The axon endings of the sinus gland are also stained. None of the other groups of neurosecretory cells in the eyestalk shows fluorescence. Preabsorption of the antiserum with pure hyperglycemic hormone abolishes the fluorescence.

Animals↗
PubMed2026

Molecular mechanisms of neuroendocrine regulation of molting in the Chinese mitten crab (Eriocheir sinensis): A transcriptomic analysis based on eyestalk ablation model.

Molting disability severely restricts the sustainable aquaculture of the Chinese mitten crab, yet the neuroendocrine mechanisms coordinating physiological responses remain poorly understood. Using unilateral eyestalk ablation to remove the primary source of molt-inhibiting hormone (MIH), we performed time-resolved transcriptomic profiling of the thoracic ganglion at 24 h (early premolt) and 48 h (ecdysis) post-ablation. We identified 2825 differentially expressed genes and uncovered a biphasic molecular response. At 24 h, the thoracic ganglion activates pathways associated with neuromuscular adaptation, oxidative stress, and cardiac muscle contraction. Notably, the arachidonic acid metabolism pathway is selectively rewired: cytochrome P450 ω-hydroxylases (CYP2J2, CYP4V2) are upregulated, while competing branches (epoxide hydrolase, cyclooxygenase) are suppressed, promoting local synthesis of the potent vasoconstrictor 20-HETE within the thoracic ganglion. This enzymatic switch provides a mechanistic link between MIH withdrawal and the local generation of elevated hemolymph pressure required for molting. By 48 h, the transcriptional program shifts toward chitin-based extracellular matrix remodeling, glycosphingolipid biosynthesis, and synaptic reorganization. Collectively, our findings redefine the thoracic ganglion as an active neuroendocrine integrator that translates reduced MIH signaling into phased physiological outputs, revealing a "neuro-endocrine-hemolymph pressure" regulatory axis. This study provides novel molecular targets (e.g., CYP2J2, CHS1, UGCG) for mitigating molting disability in E. sinensis aquaculture.

Animals↗
PubMed1979

Isolation and purification of a neurodepressing hormone from the eyestalk of Procambarus bouvieri (Ortmann).

1. A neurodepressing hormone has been isolated and purified to homogeneity from aqueous extracts of 2000 eyestalks of the Mexican crayfish Procambarus bouvieri (Ortmann). 2. Purification was achieved by gel filtration on Sephadex G-25 and G-15, and preparative paper electrophoresis at four pH valueimately 1200 molecular weight and composed of neutral amino acids. 5. No N-terminal group could be found. From its electrophoretic behavior it is concluded that the C-terminal group is also blocked.

Amino Acids↗
PubMed1977

[Eyestalk removal and intensive regeneration: joint effects on the molting cycle of Pachygrapsus marmoratus (Crustacea, Decapoda), variability of the critical regeneration stage].

When eyestalk-removal and pereiopod-removal, followed by intensive regeneration, are realized together on the same animal, their accelerative effect on the moulting rate is lower than the effect of only one of these two processes. The critical stage of pereiopod regeneration varies between the moulting stages C4 to D1 according to the physiological state of the Crab.

Animals↗
PubMed1977

[Unilateral change in color produced by ablation of the eyestalk of the crustacean Processa edulis (Decapoda, Natantia)].

A difference of expansion of erythrophores is observed between the left and right side of P. edulis after the removal of only one Eyestalk. It is the first time, in the Crustacea, that experiments lead to the conclusion that a sympathetic-like constrictor nervous action can exist in colour-change control; colour changes are particularly fast in this species.

Animals↗
PubMedDate not supplied

[The effect of eyestalk extirpation on the development of Pisidia longicornis (Crustacea, Decapoda, Anomura) (author's transl)].

Eyestalk removal has been performed on the larvae of Pisidia longicornis the first day after moulting to the second zoea stage. In the eyestalkless animals: -- The duration of the second zoea stage is not significantly affected. -- The megalopa stage is always abbreviated. -- The megalopae exhibits a reduced color-pattern.-- Difficulties occur often during moulting to the adult stage. -- The pleopods of some first and even second or third stage adults retain some setae.

Animals↗
PubMed1976

[Development of the neurosecretory system of the eyestalk of larval Astacus leptodactylus salinus (Crustacea Decapoda Reptania): photon microscopy].

Using the alcian blue-alcian yellow staining method, the neurosecretory system in the eyestalk of the Crayfish Astacus leptodactylus is studied during the period following the first, second, third and fourth moult after hatching. On the basis of their staining affinities, six different cell types are distinguishable, always spread over the four optic ganglia and varying in number depending upon the moment of sampling. A clearly recognizable sinus gland is present in the period following the third and fourth moult after hatching. During the successive stages, there occurs a shift in staining pattern of the sinus gland, which is also expressed by the variation in number of the various stained cell types.

Astacoidea↗
PubMed1979

Immunocytochemical demonstration of the neurosecretory X-organ complex in the eyestalk of the crab Carcinus maenas.

An antiserum was obtained by immunizing rabbits with sinus gland extracts from Carcinus maenas. The antiserum is almost exclusively directed against neurosecretory material in the medulla terminalis X-organ (MTGXO), as demonstrated by the peroxidase--antiperoxidase (PAP) staining method in light and electron microscopic studies. Radioimmunological binding studies indicate the presence of antibodies against the crustacean hyperglycemic hormone (CHH) or the black pigment dispersing hormone (BPDH) in the antiserum. The results suggest that the neurosecretory perikarya of the MTGXO are the sites of production of CHH and/or BPDH.

Animals↗
PubMed1979

Immunocytochemical localization of hyperglycemic hormone (HGH) in the neurosecretory system of the eyestalk of the crayfish Astacus leptodactylus.

Hyperglycemic hormone (HGH) from Astacus leptodactylus can be visualized by an immunocytochemical procedure using a specific antiserum against HGH and the peroxidase-anti-peroxidase (PAP) method. HGH containing cells are localized in the most distal portion of the x-organ in the medulla terminalis. Their cell diameter is about 47 +/- 7 micrometer; the nucleus measures about 22 +/- 2 micrometer. They form a subgroup of neurosecretory cell type 1, already described for the crayfish. A large amount of this HGH material is homogeneously stored in the sinus gland. A group of fibres in the x-organ - sinus gland - tractus can be followed, due to their positive reaction with the PAP-reagent.

Animals↗