Deficiency of nucleosome-destabilizing factor GLYR1 dampens spermatogenesis in mice.

Aberrant sperm morphology hinders sperm motility and causes male subfertility. Spermatogenesis, a complex process in male germ cell development, necessitates precise regulation of numerous developmental genes. However, the regulatory pathways involved in this process remain partially understood. We have observed the widespread expression of Glyr1, the gene encoding a nucleosome-destabilizing factor, in mouse testicular cells. Our study demonstrates that mice experiencing Glyr1 depletion in spermatogenic cells exhibit subfertility characterized by a diminished count and motility of spermatozoa. Furthermore, the rate of sperm malformation significantly increases in the absence of Glyr1, with a predominant occurrence of head and neck malformation in spermatozoa within the cauda epididymis. Additionally, a reduction in spermatocyte numbers across different meiotic stages is observed, accompanied by diminished histone acetylation in spermatogenic cells upon Glyr1 depletion. Our findings underscore the crucial roles of Glyr1 in mouse spermiogenesis and unveil novel insights into the etiology of male reproductive diseases.

Water permeability of different aerial tissues of carnations is related to cuticular wax composition.

Cuticular wax protects aerial plant tissues against uncontrolled water loss. To compare the differences among tissues, cultivars, and postharvest stages, we characterized the surface morphology, water permeability, and chemical composition of cuticular wax on the leaf, calyx, and petals of two carnation cultivars ('Master' and 'Lady green') at two postharvest stages. Obvious differences in these characteristics were found among tissues but not among cultivars or postharvest stages. The leaf surface was relatively smooth, whereas convex cells were observed on the petals. The mean minimum conductance of leaves was significantly higher than that of the calyx, followed by that of petals. It ranged between 8.8 × 10-4  m s-1 for 'Lady green' leaves at Stage II and 3.6 × 10-5  m s-1 for 'Master' petals at Stage I. Petal wax contained high concentrations of n-alkanes, whereas primary alcohols dominated in leaf wax. The weighted average chain length (ACL) was higher in petal wax than in leaf wax; it ranged from 19.6 in 'Lady green' leaves to 24.14 in 'Lady green' petals at Stage I. In conclusion, carnation petals are characterized by numerous convex cells on both the adaxial and abaxial surfaces, and their main cuticular wax components, alkanes, have a higher ACL than leaf cuticular wax, which contributes to their higher water barrier property. The results provide further evidence for the association between cuticular chemical composition and the physiological function of the cuticle in blocking water transpiration.

Aberrant Expression of Mitochondrial SAM Transporter SLC25A26 Impairs Oocyte Maturation and Early Development in Mice.

The immature germinal vesicle (GV) oocytes proceed through metaphase I (MI) division, extrude the first polar body, and become mature metaphase II (MII) oocytes for fertilization which is followed by preimplantation and postimplantation development until birth. Slc25a26 is the gene encoding S-adenosylmethionine carrier (SAMC), a member of the mitochondrial carrier family. Its major function is to catalyze the uptake of S-adenosylmethionine (SAM) from cytosol into mitochondria, which is the only known mitochondrial SAM transporter. In the present study, we demonstrated that excessive SLC25A26 accumulation in mouse oocytes mimicked naturally aged oocytes and resulted in lower oocyte quality with decreased maturation rate and increased reactive oxygen species (ROS) by impairing mitochondrial function. Increased level of Slc25a26 gene impacted gene expression in mouse oocytes such as mt-Cytb which regulates mitochondrial respiratory chain. Furthermore, increased level of Slc25a26 gene in fertilized oocytes slightly compromised blastocyst formation, and Slc25a26 knockout mice displayed embryonic lethality around 10.5 dpc. Taken together, our results showed that Slc25a26 gene plays a critical role in oocyte maturation and early mouse development.

Inhibition of DRP1 Impedes Zygotic Genome Activation and Preimplantation Development in Mice.

Mitochondrion plays an indispensable role during preimplantation embryo development. Dynamic-related protein 1 (DRP1) is critical for mitochondrial fission and controls oocyte maturation. However, its role in preimplantation embryo development is still lacking. In this study, we demonstrate that inhibition of DRP1 activity by mitochondrial division inhibitor-1, a small molecule reported to specifically inhibit DRP1 activity, can cause severe developmental arrest of preimplantation embryos in a dose-dependent manner in mice. Meanwhile, DRP1 inhibition resulted in mitochondrial dysfunction including decreased mitochondrial activity, loss of mitochondrial membrane potential, reduced mitochondrial copy number and inadequate ATP by disrupting both expression and activity of DRP1 and mitochondrial complex assembly, leading to excessive ROS production, severe DNA damage and cell cycle arrest at 2-cell embryo stage. Furthermore, reduced transcriptional and translational activity and altered histone modifications in DRP1-inhibited embryos contributed to impeded zygotic genome activation, which prevented early embryos from efficient development beyond 2-cell embryo stage. These results show that DRP1 inhibition has potential cytotoxic effects on mammalian reproduction, and DRP1 inhibitor should be used with caution when it is applied to treat diseases. Additionally, this study improves our understanding of the crosstalk between mitochondrial metabolism and zygotic genome activation.

Variation in Petal and Leaf Wax Deposition Affects Cuticular Transpiration in Cut Lily Flowers.

The vase life of cut flowers is largely affected by post-harvest water loss. Cuticular wax is the primary barrier to uncontrolled water loss for aerial plant organs. Studies on leaf cuticular transpiration have been widely conducted; however, little is known about cuticular transpiration in flowers. Here, the cuticular transpiration rate and wax composition of three lily cultivars were determined. The minimum water conductance of tepal cuticles was higher at the green bud than open flower stage. Lily cuticular transpiration exhibited cultivar- and organ-specific differences, where transpiration from the tepals was higher than leaves and was higher in the 'Huang Tianba' than 'Tiber' cultivar. The overall wax coverage of the tepals was higher compared to that of the leaves. Very-long-chain aliphatics were the main wax constituents and were dominated by n-alkanes with carbon (C) chain lengths of C27 and C29, and C29 and C31 in the tepal and leaf waxes, respectively. Primary alcohols and fatty acids as well as small amounts of alkyl esters, ketones, and branched or unsaturated n-alkanes were also detected in both tepal and leaf waxes, depending on the cultivar and organ. In addition, the chain-length distributions were similar between compound classes within cultivars, whereas the predominant C-chain lengths were substantially different between organs. This suggests that the less effective transpiration barrier provided by the tepal waxes may result from the shorter C-chain aliphatics in the tepal cuticle, compared to those in the leaf cuticle. These findings provide further insights to support the exploration of potential techniques for extending the shelf life of cut flowers based on cuticular transpiration barrier properties.

Cleavage-embryo genes and transposable elements are regulated by histone variant H2A.X.

During mammalian preimplantation development, stimulation of zygotic genome activation (ZGA) and transposable elements (TEs) shapes totipotency profiling. A rare mouse embryonic stem cells (mESCs) subpopulation is capable of transiently entering a state resembling 2-cell stage embryos, with subtypes of TEs expressed and ZGA genes transiently activated. In this study, we found that deletion of H2A.X in mESCs led to a significant upregulation of ZGA genes and misregulated TEs. ChIP-seq analysis indicated a direct association of H2A.X at the Dux locus for silencing the Dux gene and its downstream ZGA genes in mESCs. We also demonstrated that histone variant H2A.X is highly enriched in human cleavage embryos when ZGA genes and TEs are active. Therefore, we propose that H2A.X plays an important role in regulating ZGA genes and TEs to establish totipotency.

Copper Nanoparticles Induce Oxidative Stress via the Heme Oxygenase 1 Signaling Pathway in vitro Studies.

PURPOSE: The toxicity of copper nanoparticle (CuNP) exposure in the ovaries has attracted attention recently, but the precise molecular mechanism involved requires further investigation. We investigated the cytotoxicity of CuNPs in ovarian granulosa cells and the protective effect of heme oxygenase 1 (HO-1) against CuNP-induced damage. METHODS: Human ovarian granulosa cells (COV434) were treated with CuNPs, and cytotoxicity was evaluated using Cell Counting Kit-8 and flow cytometry assays. Oxidative stress was identified using biochemical markers of oxidation and anti-oxidation. The protein levels of mitogen-activated protein kinase 14 (MAPK14), phospho-MAPK14, nuclear factor erythroid 2-related factor 2 (Nrf2), and HO-1 were measured by immunoblotting. Subsequently, for oxidative stress parameter detection, the cells were pre-treated with hemin to induce HO-1 expression prior to CuNP treatment. RESULTS: Exposure to CuNPs decreased cell viability and the mitochondrial membrane potential, increased the apoptosis rate, and induced oxidative stress. Furthermore, hemin pretreatment induced HO-1 expression in cells, which partially reduced the accumulation of reactive oxygen species induced by CuNPs and increased the levels of antioxidant enzymes. CONCLUSION: CuNPs exert cytotoxic effects on human ovarian granulosa cells by inducing oxidative stress, and may induce HO-1 expression via the MAPK14-Nrf2 signaling pathway. Moreover, HO-1 protects against oxidative stress induced by CuNPs.

Suggestions on cleavage embryo and blastocyst vitrification/transfer based on expression profile of ACE2 and TMPRSS2 in current COVID-19 pandemic.

An outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is leading to an unprecedented worldwide health crisis. SARS-CoV-2 cell entry depends on ACE2 and TMPRSS2. Our objectives are to analysis the expression profile of ACE2 and TMPRSS2 in human spermatogenic cells, follicle cells, and preimplantation embryos, thereby providing mechanistic insights into viral entry and viral impact on reproduction. We found that ACE2 is mainly expressed during gametogenesis in spermatogonia and oocytes of antral follicles, granulosa cells of antral follicles and pre-ovulatory follicles, while TMPRSS2 almost has no expression in spermatogenic cells, oocytes or granulosa cells. In preimplantation embryos, ACE2 is expressed in early embryos before eight-cell stage, and trophectoderm of late blastocysts, while TMPRSS2 initiates its robust expression in late blastocyst stage. ACE2 and TMPRSS2 only show significant co-expression in trophectoderm of late blastocysts in all above cell types. We speculate that trophectoderm of late blastocysts is susceptible to SARS-CoV-2, and that the chance of SARS-CoV-2 being passed on to offspring through gametes is very low. Therefore, we propose that fertility preservation for COVID-19 patients is relatively safe and rational. We also recommend embryo cryopreservation and embryo transfer into healthy recipient mother at cleavage stage instead of blastocyst stage. Moreover, we unexpectedly found that co-expression pattern of ACE2 and TMPRSS2 in oocytes and preimplantation embryos in human, rhesus monkey and mouse are totally different, so animal models have significant limitations for evaluating transmission risk of SARS-CoV-2 in reproduction.

The role of miR-128-3p through MAPK14 activation in the apoptosis of GC2 spermatocyte cell line following heat stress.

BACKGROUND: MicroRNAs play a crucial role in the regulation of spermatogenesis. For example, miR-128-3p expression is known to decrease significantly after testicular hyperthermia, but the regulatory effect of this change on the spermatogenesis damage caused by heat stress remains unclear. OBJECTIVES: This study aimed to verify whether the target gene of miR-128-3p is MAPK14, which affects spermatogenic cell proliferation and apoptosis under testicular hyperthermia. MATERIALS AND METHODS: Mouse testis and GC2 spermatocyte cell line heat stress models were established. miR-128-3p expression before and after heat stress was analyzed by reverse transcription polymerase chain reaction. MAPK14 and p-MAPK14 expression was detected by Western blot, and cell apoptosis was analyzed by Annexin V-FITC/PI. Subsequently, miR-128-3p inhibitors and mimics were used to interfere with spermatocytes before and after heat stress, respectively, for correlation detection. RESULTS: Compared with the control group, the heat stress group showed decreased miR-128-3p expression, increased p-MAPK14 expression, and decreased cell proliferation activity. In the GC2-spd cell line in vitro, miR-128-3p inhibitors were found to upregulate p-MAPK14 expression, reduce cell proliferation activity, and increase apoptosis, consistent with the results obtained in the heat treatment alone. Furthermore, miR-128-3p mimics transfected in the GC2 cells after heat stress reduced p-MAPK14 expression, alleviated the decrease in cell proliferation, and decreased the apoptosis level. CONCLUSIONS: The downregulation of miR-128-3p expression plays an important role in spermatogenesis damages after testicular hyperthermia, which is probably attributable to the activation of the MAPK signaling pathway. Downregulated miR-128-3p expression induces the apoptosis and inhibits the proliferation of spermatogenic cells by promoting MAPK14 phosphorylation.

Letrozole versus laparoscopic ovarian drilling in clomiphene citrate-resistant women with polycystic ovary syndrome: a systematic review and meta-analysis of randomized controlled trials.

The objective of this systematic review was to examine the literature and to compare the effectiveness of letrozole (LE) versus laparoscopic ovarian drilling (LOD) for the induction of ovulation in women with clomiphene citrate (CC)-resistant polycystic ovary syndrome (PCOS). The PUBMED, Web of Science, and EMBASE databases were searched systematically for eligible randomized controlled trials (RCTs) from English language articles published from database inception to September 2018. Data were independently extracted and analyzed using the fixed-effects model or random-effects model according to the heterogeneity of the data. Four RCTs including 621 patients (309 in the LE group and 312 in the LOD group) met the inclusion criteria. There were no differences with regard to ovulation rate (relative risk [RR] 1.12; 95% confidence interval [CI] 0.93 to 1.34; P = 0.12, I2 = 90%, 541 patients, three studies), pregnancy rate (RR 1.21; 95% CI 0.95 to 1.53; P = 0.12, I2 = 0%, 621 patients, four studies), live birth rate (RR 1.27; 95% CI 0.96 to 1.68; P = 0.09, I2 = 19%, 541 patients, three studies), and abortion rate (RR 0.7; 95% CI 0.3 to 1.61; P = 0.40, I2 = 0%, 621 patients, four studies) between the two groups. These results indicated that LE and LOD appear to be equally effective in achieving live birth rate in patients with CC-resistant PCOS.

Effects of cold-inducible RNA-binding protein on the proliferation and apoptosis of spermatogenic cells in vitro following heat stress.

Cold-inducible RNA-binding protein (CIRBP) is reduced by scrotal hyperthermia in cryptorchidism, varicocoele and heat treatment, but there is no direct evidence clarifying the relationship between CIRBP and spermatogenesis. The aim of this study was to investigate the expression of CIRBP in GC2-spd cells (a mouse spermatocyte cell line) before and after heat treatment, and to determine the effects of the downregulation or overexpression of CIRBP on spermatocyte cell proliferation and apoptosis. GC2-spd cells overexpressing CIRBP and GC2-spd cells in CIRBP was knocked down were constructed to investigate the function of CIRBP in cell proliferation and apoptosis using a cell counting kit-8 and flow cytometry respectively. In addition, proliferation and apoptosis were evaluated in GC2-spd cells that had been heated for 30 or 60min, and were analysed 12, 24, and 48h after heat treatment. Heat treatment clearly suppressed the proliferation of GC2-spd cells, and upregulation of CIRBP expression in GC2-spd cells promoted cell proliferation and decreased apoptosis before and after heat stress; in contrast, downregulation of CIRBP expression inhibited cell proliferation and increased apoptosis. These findings suggest that CIRBP exerts a protective effect against spermatogenic injury caused by heat stress.

Chemical composition and water permeability of the cuticular wax barrier in rose leaf and petal: A comparative investigation.

Cuticular wax is the main transpiration barrier against uncontrolled water loss for all aerial plant organs. This study presents water permeability and chemical composition of the cuticle on the petals and leaves of two cultivars of Rosa chinensis ('Movie star' and 'Tineke'). Numerous cultivar- and organ-specific differences, such as the water permeability and total cuticular wax, were detected among rose petals and leaves. Overall, the permeability to water is higher in petals than in leaves, varying between 1.8 × 10-5 m s-1 ('Tineke' leaves) and 1.0 × 10-4 m s-1 ('Tineke' petals). The cuticular wax coverage ranges from 4.9 µg cm-2 ('Tineke' petals) to 13.2 µg cm-2 ('Movie star' petals). The most prominent components of the waxes are n-alkanes with the odd-numbered chain lengths C27 and C29 in petals, and C31 and C33 in leaves. The lower water permeability of leaves is deduced to be associated with the higher weighted average chain length of their acyclic cuticular waxes. This study on transpiration via the cuticular wax barrier of the leaf and petal of rose provides further insight to link the chemical composition to the cuticular transpiration barrier properties.

Follicular fluid humanin concentration is related to ovarian reserve markers and clinical pregnancy after IVF-ICSI: a pilot study.

RESEARCH QUESTION: Is humanin present in the human ovary and follicular fluid? What relationship exists between humanin concentration in the follicular fluid and ovarian reserve and clinical outcomes after IVF and intracytoplasmic sperm injection (ICSI)? DESIGN: Follicular fluid samples were collected from 179 patients undergoing their first IVF or ICSI cycle during oocyte retrieval. Ovarian tissues were collected from two patients undergoing surgery for ovarian cysts. Ovarian humanin localization was analysed using immunofluorescence staining. Expression of humanin in granulosa cells was confirmed by reverse transcription polymerase chain reaction (RT-PCR) analysis. Follicular fluid humanin levels were evaluated with enzyme-linked immunosorbent assay. Relationships between follicular fluid humanin levels and ovarian reserve markers and clinical outcomes were analysed. RESULTS: Strong humanin expression was found in the granulosa cells, oocytes and stromal cells of the ovary. Agarose gel electrophoresis of RT-PCR products showed rich humanin mRNA expression in human granulosa cells (119 bp). Follicular fluid humanin concentrations ranged from 86.40 to 417.60 pg/ml. They significantly correlated with FSH (r = -0.21; P < 0.01), LH (r = -0.18; P = 0.02), antral follicle count (r = 0.27; P < 0.01), anti-Müllerian hormone (r = 0.24; P = 0.03) and inhibin B (r = 0.46; P < 0.01) levels. Patients were subdivided into four groups according to follicular fluid humanin concentration quartiles (Q1-Q4). Patients in Q4 were more likely to achieve a pregnancy than Q1 (OR = 3.60; 95% CI 1.09 to 11.84). CONCLUSIONS: Humanin concentration in the follicular fluid was positively associated with ovarian reserve and clinical pregnancy rate.

Copper nanoparticle-induced uterine injury in female rats.

Copper nanoparticles (Cu-NPs) have been used increasingly in various products and applications. Although recent studies have reported that exposure to Cu-NPs leads to organ accumulation and obvious toxicity, it remains unclear whether Cu-NPs can be translocated to and cause damage in the uterus. In this study, we investigated the potential for uterine injury and gene expression patterns in female rats exposed to 3.12, 6.25, or 12.5 mg/kg/d Cu-NPs via intraperitoneal injection for 14 consecutive days. The results indicated that exposure to Cu-NPs led to significant decreases in the relative uterine weight coefficients and increases in inflammatory cell infiltration, mitochondrial swelling and vacuolization, shortened and reduced endometrial epithelial cell microvilli, and apoptosis. Furthermore, exposure to Cu-NPs increased malondialdehyde (MDA) accumulation and decreased superoxide dismutase (SOD) levels. Signal transduction mechanism studies indicated that exposure to Cu-NPs activated caspases 3, 8, and 9 and BH3 interacting domain death agonist (tBid), reduced B cell leukemia/lymphoma 2 (Bcl-2) expression, and increased the expression of apoptotic peptidase activating factor 1 (Apaf-1), BCL2-associated X, apoptosis regulator (Bax), and cytochrome c. A microarray analysis revealed significant alterations in the expression of 963 genes; of these, 622 were upregulated and 341 were downregulated. The results of further evaluations of some altered genes, including matrix metallopeptidase 12 (Mmp12), using quantitative RT-PCR agreed with the microarray findings. These results provide strong evidence that Cu-NPs can trigger both intrinsic and extrinsic apoptotic pathways to mediate uterine injury, resulting in oxidative stress-related changes in gene expression.

Effect of a novel copper-containing intrauterine device material on the endometrial environment in rabbits.

OBJECTIVE(S): This study aimed to determine whether intrauterine placement of a novel composite material [copper (Cu) microparticles, low-density polyethylene, and methyl vinyl silicone rubber (Cu/LDPE/MVQ)] could prevent pregnancy in rabbits, and to evaluate the effects of Cu/LDPE/MVQ on the endometrial environment. STUDY DESIGN: Eighty sexually mature female rabbits were randomly divided into four groups (n=20 each group): control (sham-operated), LDPE/MVQ, Cu/LDPE/MVQ microcomposite, and bare Cu. Ten rabbits from each implant-bearing group were randomly selected for a mating experiment beginning 30 days after insertion. Pregnancy outcomes were observed 15 days after mating. Factors associated with endometrial bleeding and inflammation in the remaining rabbits in each group, and the surface conditions of the implants, were investigated 90 days post-insertion. RESULTS: The Cu (0 embryo) and Cu/LDPE/MVQ (0 embryo) groups had significantly fewer embryos than the LDPE/MVQ (1.0±0.6 embryos, p<.05) and sham-operated groups (4.1±1.3 embryos, p<.05). Compared with bare Cu, the Cu/LDPE/MVQ composite material was associated with considerable reductions in injuries and factors associated with abnormal endometrial bleeding and inflammation, such as matrix metalloproteinase 9 (MMP9) and prostaglandin E2 (PGE2). Additionally, the surface of implanted Cu/LDPE/MVQ remained much smoother than that of implanted bare Cu. CONCLUSION(S): This novel Cu-containing intrauterine device material exhibits a similar effect in prevention of pregnancy with bare copper, and lower levels of inflammatory markers. IMPLICATIONS: This study demonstrates the potential of the novel Cu/LDPE/MVQ microcomposite material as a future substitute for conventional intrauterine device materials.

Antifertility effectiveness of a novel copper-containing intrauterine device material and its influence on the endometrial environment in rats.

This study was designed to investigate the antifertility effectiveness of a novel copper-containing intrauterine device material containing a composite of micro-copper (Cu), low-density polyethylene (LDPE), and methyl vinyl silicone rubber (MVQ) and its effects on the endometrial environment in rats. The contraceptive effectiveness was examined 12 days after pregnancy. The pathological changes; factors associated with bleeding, pain, and inflammation in the endometrium; and the surface condition of the implants were investigated after insertion for 90 days. Furthermore, the release rate of copper ions in simulated uterine solution (SUS) was investigated for 270 days. The contraceptive effectiveness was 100% in both the bulk Cu and micro-Cu/LDPE/MVQ groups, and that in the LDPE/MVQ group was 30%. On day 90 after insertion, histopathological observation and the ultrastructural changes in the endometrium showed that the damage caused by bulk Cu was much more severe than that caused by the Cu/LDPE/MVQ microcomposite and that the surface of the latter was much smoother than that of the former. Furthermore, compared with the sham-operated control group, the concentrations of tissue plasminogen activator and prostaglandin E2 were significantly increased 90 days after insertion in all of the experimental groups except for the LDPE/MVQ group (P < 0.05), and the parameters in the Cu/LDPE/MVQ group were significantly lower than those in the Cu group (P < 0.05). In addition, the expression levels of matrix metalloproteinase 9, metalloproteinase 1 tissue inhibitor, plasminogen inhibitor 1, CD34, vascular endothelial growth factor, substance P, and substance P receptor in the endometrium in all of the experimental groups were significantly lower than those in the Cu group 90 days after insertion (P < 0.05). The results of this study indicate that micro-Cu/LDPE/MVQ exhibits satisfactory contraceptive efficacy and causes fewer side effects than Cu.

Next-generation sequencing-based microRNA profiling of mice testis subjected to transient heat stress.

This study aimed to investigate the role of microRNA (miRNA) in heat stress-induced spermatogenic impairment. Testes from 15 adult ICR mice subjected to testicular hyperthermia at 43°C for 30 min and from 15 control mice were collected and pooled into 3 samples. Isolated RNA from these samples was subjected to small RNA high-throughput sequencing, and differentially expressed miRNAs were identified and validated using RT-PCR. The identified miRNAs were further subjected to Gene Ontology and KEGG analyses, which revealed significant enrichment for pathways potentially involved in heat stress-induced spermatogenic impairment. Additionally, a correlation analysis of the relative levels of validated miRNAs with germ cell apoptosis was performed. Of the 11 miRNAs identified as differentially expressed, 8 were validated as consistent with sequencing data. Further analyses suggested that the target genes of those miRNAs were involved in various pathways (e.g., ribosomal, HIF-1, MAPK) that may be critical to heat stress-induced testicular damage. Some identified miRNAs, including miR-449a-3p, miR-92a-1-5p, miR-423-3p, and miR-128-3p, correlated closely with germ cell apoptosis. The study results reveal a detailed miRNA profile of heat stress-induced testicular damage and highlight new and potentially important candidate targets in the process of male infertility.

Effect of nitric oxide on ethylene synthesis and softening of banana fruit slice during ripening.

The effects of nitric oxide (NO) on ethylene synthesis and softening of ripening-initiated banana slice were investigated. Fruit firmness, color, and contents of starch and acid-soluble pectin (ASP) were measured. In addition, ethylene production, 1-aminocyclopropane-1-carboxylic acid (ACC) content, expression and activities of ACC synthase (ACS) and ACC oxidase (ACO), and activities of cell-wall-modifying enzymes, polygalacturonase (PG), pectin methylesterase (PME), and endo-beta-1,4-glucanase, were analyzed. Application of NO reduced ethylene production, inhibited degreening of the peel and delayed softening of the pulp. The decrease of ethylene production was associated with the reduction in the activity of ACO and the expression of the MA-ACO1 gene. Moreover, the NO-treated fruit showed a lower expression of the MA-ACS1 gene but higher ACS activity and ACC content. In addition, NO treatment decreased the activities of PG, PME, and endo-beta-1,4-glucanase and maintained higher contents of ASP and starch, which may account for the delay of softening. We proposed that the inhibition of ACO activity and transcription of gene MA-ACO1 by NO resulted in decreased ethylene synthesis and the delay of ripening of banana slice.

Effects of reactive oxygen species on cellular wall disassembly of banana fruit during ripening.

Fruit softening is generally attributed to cell wall disassembly. Experiments were conducted to investigate effects of various reactive oxygen species (ROS) on in vitro cellular wall disassembly of harvested banana fruit. The alcohol-extracted insoluble residue (AEIR) was obtained from the pulp tissues of banana fruit at various ripening stages and then used to examine the disassembly of cellular wall polysaccharides in the presence of superoxide anion (O2(-)), hydrogen peroxide (H2O2) or hydroxyl radical (OH) and their scavengers. The presence of OH accelerated significantly disassembly of cellular wall polysaccharides in terms of the increase in contents of total sugars released and uronic acid, and the decrease in molecular mass of soluble polysaccharides, using gel permeation chromatography. However, the treatment with H2O2 or O2(-) showed no significant effect on the disassembly of cellular wall polysaccharides. Furthermore, the degradation of the de-esterified AEIR was more susceptible to OH attack than the esterified AEIR. In addition, the effect of OH could be inhibited in the presence of OH scavenger. This study suggests that disassembly of cellular wall polysaccharides could be initiated by OH as the solublisation of the polysaccharides increased, which, in turn, accelerated fruit softening.