Characterization,expression dynamics,and potential function of OPA1 for regulation of mitochondrial morphology during spermiogenesis in Phascolosoma esculenta

Mitochondria undergo morphological changes during spermatogenesis in some animals.The mechanism and role of mitochondrial morphology regulation,however,remain somewhat unclear.In this study,we analyzed the molecular characteristics,expression dynamics and subcellular localization of optic atrophy protein 1(OPA1),a mitochondrial fusion and cristae maintenance-related protein,to reveal the possible regulatory mechanisms underlying mitochondrial morphology in Phascolosoma esculenta spermiogenesis.The full-length cDNA of the P.esculenta opa1 gene(Pe-opa1)is 3743 bp in length and encodes 975 amino acids.The Pe-OPA1 protein is highly conservative and includes a transmembrane domain,a GTPase domain,two helical bundle domains,and a lipid-interacting stalk.Gene and protein expression was higher in the coelomic fluid(a site of spermatid development)of male P.esculenta and increased first and then decreased from March to December.Moreover,their expression during the breeding stage was significantly higher than during the non-breeding stage,suggesting that Pe-OPA1 is involved in P.esculenta reproduction.The Pe-OPA1 protein was more abundant in components consisting of many spermatids than in components without,indicating that Pe-OPA1 mainly plays a role in the spermatid in coelomic fluid.Moreover,Pe-OPA1 was mainly detected in the spermatid mitochondria.Immunofluorescence experiments showed that the Pe-OPA1 are constitutively expressed and co-localized with mitochondria during spermiogenesis,suggesting its involvement in P.esculenta spermiogenesis.These results provide evidence for Pe-OPA1's involvement in the regulation of mitochondrial morphology during spermiogenesis.

Combined proteomic and metabolomic studies on the liver of Amur sturgeon Acipenser schrenckii under titanium dioxide nanoparticle exposure

Nanomaterials,particularly titanium dioxide nanoparticles(TiO_(2)-NPs),are extensively utilized across various industries.However,their environmental release has raised concerns regarding their potential ecological and environmental impacts.The reproductive toxicity of TiO_(2)-NPs in fish species has attracted considerable attention,yet conflicting research outcomes have been reported.We investigated the effects of TiO_(2)-NPs exposure on the liver of juvenile Amur sturgeon Acipenser schrenckii using label-free proteomic and untargeted metabolomic analyses.The experiment included a control group and three groups exposed to different concentrations of TiO_(2)-NPs(low,TL;medium,TM;high,TH).Compared to the control group,9,19,and 25 proteins and 35,73,and 158 metabolites were differentially expressed in the TH,TM,and TL TiO_(2)-NP-exposed groups,respectively.The differentially expressed genes(DEGs)were enriched in the Kyoto Encyclopedia for Genes and Genomes(KEGG)pathways related to glycolysis and gluconeogenesis.Moreover,among the 126 correlated proteins,the most enriched pathways were associated with endocytosis and protein processing in the endoplasmic reticulum.Notably,syringic acid was significantly downregulated across all three TiO_(2)-NP-exposed groups.To obtain a comprehensive overview of the TiO_(2)-NP-induced expression changes,a co-regulated network of proteins and metabolites associated with TiO_(2)-NPs exposure was constructed.Exposure to TiO_(2)-NPs led to enrichment and alteration of pathways related to immune responses,including endocytosis,protein processing in the endoplasmic reticulum,and peroxisome proliferator-activated receptor(PPAR)signaling.In conclusion,our findings indicate that exposure to TiO_(2)-NPs might disrupt glucose metabolism and induce immune responses,thus contributing to our understanding of the environmental impacts of nanomaterials and highlighting the need for further research and development of potential mitigation strategies.

Environmental hypoxia induces apoptosis in large yellow croaker Larimichthys crocea via both intrinsic and extrinsic pathways

Hypoxia has become an unfavorable factor affecting the sustainable development of the large yellow croaker Larimichthys crocea,an economically important mariculture fish in China.Apoptosis is a consequence of hypoxia on fish.However,the effects of hypoxia stress on apoptosis in L.crocea remain largely unknown.We investigated the effect of environmental hypoxia on apoptosis in L.crocea.Results show that hypoxia induced apoptosis in L.crocea both in vivo and in vitro.The mitochondrial membrane potential was significantly reduced in large yellow croaker fry(LYCF)cells.The expression levels of Bcell lymphoma/leukemia-2(Bcl-2)m RNA and protein were also significantly decreased in the liver and LYCF cells during 96 h and 48 h of hypoxia stress,respectively,whereas the expression level of Bcl-2 associated X(Bax)mRNA,Casp3 mRNA,and activity of caspase-3/7/9 were significantly increased,indicating that hypoxia induced caspase-dependent intrinsic apoptosis in L.crocea.The expression level of the apoptosis-inducing factor(AIF)protein was significantly increased in the liver and LYCF cells.The level of AIF protein was significantly decreased in the cytoplasm but increased in the nuclei of L.crocea,demonstrating that hypoxia induced the AIF-mediated caspase-independent intrinsic apoptosis.In addition,the activity of caspase-8 was significantly increased,indicating that hypoxia stress induced extrinsic apoptosis in L.crocea.Therefore,hypoxia induced apoptosis in L.crocea through both the intrinsic and extrinsic pathways.The present study accumulated basic biological information to help elucidate the mechanism of hypoxia response in marine fish.

Roles of Adinandra nitida(Theaceae) and camellianin A in HCl/ethanol-induced acute gastric ulcer in mice

Gastric ulcer is a global health concern nowadays. Adinandra nitida, known as Shibi tea, is a flavonoidrich plant found in South China. A. nitida possesses many healthy properties, such as antioxidation and reducing blood pressure. However, its effects on gastric ulcer have not been investigated. This study aimed to investigate the effects of the Shibi tea water extract(STE) and its main flavonoid camellianin A(CA) in hydrochloric acid(HCl) and ethanol(Et OH)-induced acute gastric ulcer in mice. Administration of CA and STE for continuous two days after stimulation by HCl/Et OH significantly attenuated the deterioration of gastric mucosal damage by lowering the gross gastric mucosal index, histopathological injury index, the oxidative stress, the expression of the inflammatory cytokines TNF-α and IL-6, and the expression of inflammatory mediators i NOS and COX-2. Western blotting and immunohistochemistry analysis showed that CA and STE regulated the inflammatory signaling pathway protein levels of IκB-α and NF-κB. Taken together, our study verified that CA and STE have antioxidative and anti-inflammatory effects in gastric ulcer mice. We propose that A. nitida should be developed as natural functional food for acute gastric ulcer patients base on the gastroprotective effects of STE and its main flavonoid CA.

Evidence for the role of KIF17 in fish spermatid reshaping:expression pattern of KIF17 in Larimichthys polyactis spermiogenesis

The homodimeric kinesin-2 protein KIF17 functions in intracellular transport and spermiogenesis in mammals.However,its role in fish spermiogenesis has not been reported.Here,we aimed to clone full-length kif17 cDNA and determine the molecular characteristics and expression patterns of KIF17 in Larimichthys polyactis spermiogenesis.The full-length cDNA of L.polyactis kif17(Lp-kif17)was sequenced and found to contain a 332-bp 5′untranslated region,480-bp 3′untranslated region,and 2433-bp open reading frame encoding 810 amino acids.Bioinformatics analyses showed that L.polyactis KIF17(Lp-KIF17)shared high sequence similarity with homologs in other animals and possessed an N-terminal motor domain with microtubule-binding sites and adenosine triphosphate(ATP)hydrolysis sites,a stalk domain containing two coiled-coil regions,and a C-terminal tail domain.The Lp-kif17 mRNA was widely expressed in various tissues,with the highest level in the brain,followed by that in the testis.Fluorescence in situ hybridization(FISH)analysis revealed that Lp-kif17 was continuously expressed in spermiogenesis,showing that it had potential functions in this process.Using immunofluorescence(IF)analysis,we found that Lp-KIF17 colocalized with tubulin and was transferred from the perinuclear cytoplasm to the side of spermatid where the tail forms during spermiogenesis.These findings suggested that KIF17 is involved in L.polyactis spermiogenesis.In particular,it may participate in nuclear shaping and tail formation by interacting with perinuclear microtubules during spermatid reshaping.In addition to providing evidence for the role of KIF17 in fish spermatid reshaping,this study provides important data for studies of reproductive biology in L.polyactis.

Physiological and histological responses of Phascolosoma esculenta (Sipuncula: Phascolosomatidea) to acute heat stress

Temperature is an important factor affecting the growth,development,and survival of organisms.The effects of temperature stress on aquatic organisms have received increasing attention,as these organisms are mostly poikilotherms and their body temperature are directly corresponding changes with ambient temperature,resulting in they are easily exposed in temperature stress.However,little is known about the effects of high temperature on Sipuncula.In this study,we investigated the effects of acute heat stress on malondialdehyde(MDA)concentration,the activities of antioxidant(superoxide dismutase and glutathione peroxidase)and immunity-related(acidic and alkaline phosphatase)enzymes,heat shock protein 70(hsp70)and hsp90 gene expression,and the histological structure of the sipunculid Phascolosoma esculenta.Within the coelom fl uid,the MDA concentration and all detected antioxidant enzyme activities increased during high temperature stress;signifi cant increases were also observed here and in the intestine in the hsp70 and hsp90 mRNA expression levels.These results indicated that acute heat stress caused oxidative stress;antioxidants and heat shock proteins probably act to protect P.esculenta against oxidative damage,constituting part of its physiological mechanism for adaptation to high temperatures.In addition,the increased activity of the acidic and alkaline phosphatases indicated eff ects on its nonspecifi c immune system.Furthermore,damaged tissue structures were observed in the body wall,retractor muscle,intestine,and nephridium after 96 h of 40-℃ stress.The damaged cells of these tissues showed obvious condensed chromatin around the nuclear membrane.This histological damage suggests that heat stress could affect movement,food absorption,digestion,and excretion in P.esculenta.These results elucidate the effects of temperature stress on P.esculenta and its physiological response mechanisms and provide practical indicators for assessing heat stress status and determining suitable culture temperatures for P.esculenta.