Osiris17 is indispensable for morphogenesis of intestinal tract in Locusta migratoria.

The Osiris gene family is believed to play important roles in insect biology. Previous studies mainly focused on the roles of Osiris in Drorophila, how Osiris operates during the development of other species remains largely unknown. Here, we investigated the role of LmOsi17 in development of the hemimetabolous insect Locusta migratoria. LmOsi17 was highly expressed in the intestinal tract of nymphs. Knockdown of LmOsi17 by RNA interference (RNAi) in nymphs resulted in growth defects. The dsLmOsi17-injected nymphs did not increase in body weight or size and eventually died. Immunohistochemical analysis showed that LmOsi17 was localized to the epithelial cells of the foregut and the gastric caecum. Histological observation and hematoxylin-eosin staining indicate that the foregut and gastric caecum are deformed in dsLmOsi17 treated nymphs, suggesting that LmOsi17 is involved in morphogenesis of foregut and gastric caecum. In addition, we observed a significant reduction in the thickness of the new cuticle in dsLmOsi17-injected nymphs compared to control nymphs. Taken together, these results suggest that LmOsi17 contributes to morphogenesis of intestinal tract that affects growth and development of nymphs in locusts.

Artificial Intelligence-Assisted RFID Tag-Integrated Multi-Sensor for Quality Assessment and Sensing.

Radio frequency identification (RFID) is well known as an identification, track, and trace approach and is considered to be the key physical layer technology for the industrial internet of things (IIoT). However, IIoT systems have to introduce additional complex sensor networks for pervasive monitoring, and there are still challenges related to item-level sensing and data recording. To overcome the shortage, this work proposes an artificial intelligence (AI)-assisted RFID-based multi-sensing technology. Both passive and semi-passive RFID tag-integrated multi-sensors are developed. The main contributions and the novelty of this investigation are as follows. A UHF RFID tag-integrated multi-sensor with a boosted charge pump is proposed; it enables high RF signal sensitivity and a long operational range. The whole hardware design, including the antenna and energy harvester, are studied. Moreover, a demonstration with real-world ham product sensing data is conducted. This work also proposes and successfully demonstrates the integration of machine learning algorithms, specifically the NARX neural network, with RFID sensing data for food product quality assessment and sensing (QAS). This application of machine learning to RFID-generated data for quality assessment is also a novel aspect of the research. The deployment of an autoregressive model with an exogenous input (NARX) neural network model, tailored for nonlinear processes, emerges as the most effective, achieving a root mean square error (RMSE) of 0.007 and an R-squared value of 0.99 for ham product QAS. By deploying the technology, low-cost, timely, and flexible product QAS can be achieved in manufacturing industries, which helps product quality improvement and the optimization of the manufacturing line and supply chain.

IRF-1-inhibited lncRNA XIST regulated the osteogenic differentiation via miR-450b/FBXW7 axis.

Osteoporosis influences life quality among elder people. Osteoblast dysfunction could cause the occurrence of osteoporosis. LncRNA XIST are involved in the progression of osteoporosis. However, the correlation between IRF-1 and XIST in osteogenic differentiation remains unclear. In the study, Clinical samples were collected for the analysis of XIST level. mRNA and protein levels were detected by RT-qPCR and western blot, respectively. H&E staining was performed to observe the histological changes in mice. Alizarin Red Staining was applied to assess the calcium deposits in hBMSCs. Meanwhile, the relation among XIST, miR-450b and FBXW7 was investigated by dual luciferase assay and ChIP. In vivo model was constructed to assess the impact of XIST in osteoporosis. XIST was found to be upregulated in osteoporosis, and XIST overexpression could inhibit the osteogenic differentiation in hBMSCs. IRF-1 could transcriptionally inhibit the expression of XIST, and XIST could inhibit osteogenic differentiation through binding with miR-450b in hBMSCs. In addition, miR-450b significantly promoted the osteogenic differentiation in hBMSCs via targeting FBXW7. Furthermore, XIST knockdown could inhibit the symptom of osteoporosis in vivo. IRF-1 promoted the osteogenic differentiation via mediation of lncRNA XIST/miR-450b/FBXW7 axis, and this finding might shed novel insights on exploring new ideas against osteoporosis.

Jinggangmycin stimulates reproduction and increases CHCs-dependent desiccation tolerance in Drosophila melanogaster.

Jinggangmycin (JGM), an agricultural antibiotic compound, is mainly used against the rice sheath blight (RSB) Rhizoctonia solani. However, its application may lead to unexpected consequences in insects. In this study, the effects of JGM on the physiological parameters of Drosophila melanogaster were investigated. The results showed that 0.005 g/ml JGM exposure increased female daily egg production and extended the oviposition period, while there was no significant effect on reproduction at 0.016 g/ml. At the same time, desiccation tolerance increased in flies fed 0.005 g/ml JGM. The RT-qPCR results revealed that FAS1 and FAS3 expression were upregulated in 0.005 g/ml JGM treated flies. Consistently, the amount of CHCs accumulated on the cuticle surface increased upon JGM treatment at 0.005 g/ml. Moreover, RNAi for FAS3 decreased desiccation tolerance of JGM-treated flies. These results suggest that JGM affects fatty acid biosynthesis, which in turn enhances reproduction and desiccation tolerance in Drosophila.

lncRNA MALAT1 promotes osteogenic differentiation through the miR-217/AKT3 axis: A possible strategy to alleviate osteoporosis.

BACKGROUND: Accumulating evidence demonstrates that long non-coding RNAs (lncRNAs) are associated with the development of osteoporosis. The present study aimed to investigate the effect of metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) on osteogenic differentiation in osteoporosis. METHODS: MALAT1 levels were detected by a real-time polymerase chain reaction (RT-qPCR). Moreover, the levels of osteogenic differentiation-related factors (Bmp4, Col1a1 and Spp1) were measured by a RT-qPCR and western blotting. Alkaline phosphatase (ALP) activity was detected using an ALP staining assay. RESULTS: MALAT1 levels were downregulated in hindlimb unloading mice and simulated in microgravity (MG) treated MC3T3-E1 cells. Moreover, MG treatment induced the downregulation of the expression of ALP, BMP4, Col1a1 and Spp1, whereas overexpression of MALAT1 abolished the downregulation. MG also inhibited ALP activity, whereas MALAT1 reversed the effect. Furthermore, miR-217 was identified as a target of MALAT1, and AKT3 was verified as a target of miR-217. Overexpression of miR-217 rescued the promotion of osteogenic differentiation induced by MALAT1 in MG treated cells. Knockdown of AKT3 abolished the facilitation of osteogenic differentiation induced by downregulation of miR-217. CONCLUSIONS: MALAT1 promotes osteogenic differentiation through regulating miR-217/AKT3 axis, suggesting that MALAT1 is a potential target with respect to alleviating osteoporosis.

Resveratrol Promotes Osteogenic Differentiation of Bone Marrow-Derived Mesenchymal Stem Cells Through miR-193a/SIRT7 Axis.

Resveratrol (RES) is a novel dietary phenol compound derived from plants and has been studied extensively for its health benefit and medical potential including osteoporosis. The purpose of this study is to investigate the role of resveratrol in osteoporosis in vivo and in vitro and explore the mechanism of osteogenic differentiation of BMSCs. RT-qPCR, ELISA, and Western blot were used to measure the expression level of miR-193a, SIRT7, and osteogenic markers proteins. The interaction between miR-193a and SIRT7 was validated by dual-luciferase reporter assay. Moreover, MTT assay was conducted to detect cell viability. Alizarin red s staining was used to examine bone formation and calcium deposits. The ovariectomized rat model was set up successfully and HE staining was used to examine femoral trabeculae tissue. Our results showed that miR-193a was overexpressed, while SIRT7 was downregulated in osteoporosis. RES suppressed miR-193a to promote osteogenic differentiation. Mechanically, miR-193a targeted and negative regulated SIRT7. Additionally, it was confirmed that SIRT7 promoted osteogenic differentiation of BMSCs through NF-κB signaling pathway. Further study indicated that RES exerted its beneficial function through miR-193a/SIRT7-mediated NF-κB signaling to alleviate osteoporosis in vivo. Our research suggested that the RES-modulated miR-193a inhibition is responsible for the activation of SIRT7/NF-κB signaling pathway in the process of osteogenic differentiation, providing a novel insight into diagnosis and treatment of osteoporosis.

Associations between albumin, globulin, albumin to globulin ratio and muscle mass in adults: results from the national health and nutrition examination survey 2011-2014.

INTRODUCTION: Chronic inflammation and malnutrition play important roles in muscle loss. Although albumin, globulin and albumin to globulin ratio (AGR) are considered to be useful inflammatory-nutritional biomarkers, their relationship with muscle mass remain unclear. This study aimed to investigate the relationship between them in adults. METHODS: We utilized data from the National Health and Nutrition Examination Survey (NHANES) 2011-2014 for analysis. Data on albumin, globulin, appendicular skeletal muscle mass, body mass index (BMI) and potential confounders (sociodemographic characteristics, medical conditions, laboratory parameters) were extracted and analyzed. We conducted multivariate linear regression models and smooth curve fittings to investigate the association between albumin, globulin, AGR and muscle mass. Subgroup analysis based on gender and muscle mass were performed. RESULTS: A total of 4110 participants were included, there were 294 participants with low muscle mass (LMM) and 3816 participants with normal muscle mass (NMM). LMM individuals were older, had greater prevalence of diabetes, higher BMI, globulin and triglycerides, lower albumin and AGR. Albumin was positively correlated to muscle mass in men, but negatively correlated with muscle mass in women. There were negative association between globulin and muscle mass, and positive association between AGR and muscle mass among men, but no significant associations were detected among women. Moreover, a linear relationship between albumin, globulin and muscle mass, as well as a non-linear relationship between AGR and muscle mass in men were identified. CONCLUSIONS: The relationships between albumin, globulin, AGR and muscle mass were sex-specific. We speculate these indicators may be useful in assessing muscle mass in men.

Can prophylactic negative pressure wound therapy improve clinical outcomes in spinal fusion surgery? A meta-analysis.

PURPOSE: Recently negative pressure wound therapy (NPWT) is increasingly being prophylactically used to prevent wound complications in various types of surgeries, but its role in spinal fusion surgery was less well established. This study aimed to evaluate the efficacy of prophylactic NPWT (PNPWT) usage in spinal fusion surgery. METHODS: Following PRISMA guidelines, databases PubMed, Embase and Web of Science were searched for relevant studies. Studies comparing PNPWT with standard wound dressing (SWD) were included and analyzed. The primary outcome was the incidence of surgical site infection, and secondary outcomes were incidence of wound dehiscence, overall wound complication, readmission and reoperation. RESULTS: A total of five studies were included; there were 279 patients in PNPWT group and 715 patients in SWD group. Four studies investigated surgical site infection; the pooled analysis showed a significantly lower incidence of surgical site infection in PNPWT group (OR: 0.399; 95% CI: 0.198, 0.802). Two studies explored wound dehiscence, three studies reported overall wound complication, and there were no significant differences between the two groups ((OR: 0.448; 95% CI: 0.144, 1.389) and (OR: 0.562; 95% CI: 0.296, 1.065), respectively). Two studies evaluated readmission, three studies compared reoperation rate, and the pooled results demonstrated no significant difference between the two groups ((OR: 1.045; 95% CI: 0.536, 2.038) and (OR: 0.979; 95% CI: 0.442, 2.169), respectively). CONCLUSIONS: The current evidence suggested PNPWT could effectively reduce postoperative surgical site infection, but it had no significant benefit on reducing the incidence of wound dehiscence, overall wound complication, readmission and reoperation.

Does prophylactic vertebral augmentation reduce the refracture rate in osteoporotic vertebral fracture patients: a meta-analysis.

PURPOSE: In order to prevent the recurrent fracture after vertebral augmentation, the concept of prophylactic vertebral augmentation has been proposed, but its efficacy is still controversial. This study aimed to determine the efficacy of prophylactic vertebral augmentation for prevention of refracture in osteoporotic vertebral fracture patients. METHODS: Following PRISMA guidelines, a literature search was performed using PubMed, Embase and Web of Science databases for relevant studies published until February 2021. A meta-analysis of randomized controlled trials and retrospective controlled trials comparing prophylactic group versus nonprophylactic group was conducted. The primary outcome was the incidence of new vertebral compression fracture (VCF), and secondary outcomes were incidence of adjacent vertebral fracture (AVF) and remote vertebral fracture (RVF). RESULTS: A total of 6 studies encompassing 618 patients were included in the meta-analysis. The incidence of new VCF was reported in all six studies, and the result showed no significant difference between the two groups (OR: 0.509; 95% CI: 0.184-1.409). Four studies provided data on the incidence of AVF, and it was revealed that there was no significant difference between the two groups (OR: 0.689; 95% CI: 0.109-4.371). In view of the incidence of RVF, prophylactic group also did not differ significantly compared with nonprophylactic group (OR: 0.535; 95% CI: 0.167-1.709). CONCLUSIONS: The current evidence suggested that prophylactic vertebral augmentation might not be appropriate to diminish the risk of new VCF. Therefore, there is a need to investigate the mechanism of refracture and explore other preventive regimens to reduce the risk.

What are risk factors for subsequent fracture after vertebral augmentation in patients with thoracolumbar osteoporotic vertebral fractures.

BACKGROUND: Due to its unique mechanical characteristics, the incidence of subsequent fracture after vertebral augmentation is higher in thoracolumbar segment, but the causes have not been fully elucidated. This study aimed to comprehensively explore the potential risk factors for subsequent fracture in this region. METHODS: Patients with osteoporotic vertebral fracture in thoracolumbar segment who received vertebral augmentation from January 2019 to December 2020 were retrospectively reviewed. Patients were divided into refracture group and non-refracture group according to the occurrence of refracture. The clinical information, imaging findings (cement distribution, spine sagittal parameters, degree of paraspinal muscle degeneration) and surgery related indicators of the included patients were collected and compared. RESULTS: A total of 109 patients were included, 13 patients in refracture group and 96 patients in non-refracture group. Univariate analysis revealed a significantly higher incidence of previous fracture, intravertebral cleft (IVC) and cement leakage, greater fatty infiltration of psoas (FIPS), fatty infiltration of erector spinae plus multifidus (FIES + MF), correction of body angle (BA), BA restoration rate and vertebral height restoration rate in refracture group. Further binary logistic regression analysis demonstrated previous fracture, IVC, FIPS and BA restoration rate were independent risk factors for subsequent fracture. According to ROC curve analysis, the prediction accuracy of BA restoration rate was the highest (area under the curve was 0.794), and the threshold value was 0.350. CONCLUSIONS: Subsequent fracture might cause by the interplay of multiple risk factors. The previous fracture, IVC, FIPS and BA restoration rate were identified as independent risk factors. When the BA restoration rate exceeded 0.350, refractures were more likely to occur.

Identification of key amino acid residues determining ligand binding specificity, homodimerization and cellular distribution of human galectin-10.

Charcot-Leyden crystal protein/Gal-10, abundantly expressed in eosinophils and basophils, is related to several immune diseases. Recently, crystallographic and biochemical studies showed that Gal-10 cannot bind lactose, because a glutamate residue (Glu33) from another monomer blocks the binding site. Moreover, Gal-10 actually forms a novel dimeric structure compared to other galectins. To investigate the role that Glu33 plays in inhibiting lactose binding, we mutated this residue to glutamine, aspartate, and alanine. The structure of E33A shows that Gal-10 can now bind lactose. In the hemagglutination assay, lactose could inhibit E33A from inducing chicken erythrocyte agglutination. Furthermore, we identified a tryptophan residue (Trp127) at the interface of homodimer that is crucial for Gal-10 dimerization. The variant W127A, which exists as a monomer, exhibited higher hemagglutination activity than wild type Gal-10. The solid phase assay also showed that W127A could bind to lactose-modified sepharose-6B, whereas wild type Gal-10 could not. This indicates that the open carbohydrate-binding site of the W127A monomer can bind to lactose. In addition, the distribution of EGFP-tagged Gal-10 and its variants in HeLa cells was investigated. Because Trp72 is the highly conserved in the ligand binding sites of galectins, we used EGFP-tagged W72A to show that Gal-10 could not be transported into the nucleus, indicating that Trp72 is crucial for Gal-10 transport into that organelle.

Galectin-10: a new structural type of prototype galectin dimer and effects on saccharide ligand binding.

Galectin-10 (Gal-10) which forms Charcot-Leyden crystals in vivo, is crucial to regulating lymph cell function. Here, we solved the crystal structures of Gal-10 and eight variants at resolutions of 1.55-2.00 Å. Structural analysis and size exclusion chromatography demonstrated that Gal-10 dimerizes with a novel global shape that is different from that of other prototype galectins (e.g., Gal-1, -2 and -7). In the Gal-10 dimer, Glu33 from one subunit modifies the carbohydrate-binding site of another, essentially inhibiting disaccharide binding. Nevertheless, glycerol (and possibly other small hydroxylated molecules) can interact with residues at the ligand binding site, with His53 being the most crucial for binding. Alanine substitution of the conserved Trp residue (Trp72) that is crucial to saccharide binding in other galectins, actually leads to enhanced erythrocyte agglutination, suggesting that Trp72 negatively regulates Gal-10 ligand binding. Overall, our crystallographic and biochemical results provide insight into Gal-10 ligand binding specificity.

USP17 is upregulated in osteosarcoma and promotes cell proliferation, metastasis, and epithelial-mesenchymal transition through stabilizing SMAD4.

USP17 is upregulated in several cancers, indicating that USP17 might play essential functions in tumor development. However, the function of USP17 in osteosarcoma is still unknown. Our work aimed to investigate the function of USP17 in osteosarcoma. We found that the expression of USP17 was upregulated in osteosarcoma tissues and cell lines, including MG-63 and U2OS. Several functional experiments, such as colony formation analysis, Cell Counting Kit-8 assay, wound healing analysis, and transwell assay, showed that USP17 promoted cell proliferation, migration, and invasion. Moreover, we found that USP17 facilitated migration and invasion through promoting epithelial-mesenchymal transition. SMAD4 has been found to regulate epithelial-mesenchymal transition, co-immunopurification, and glutathione S-transferase pull-down analysis demonstrated that USP17 interacted with SMAD4. Furthermore, USP17 stabilized SMAD4 through its deubiquitinase activity. In conclusion, this study shows that USP17 enhances osteosarcoma cell proliferation and invasion through stabilizing SMAD4.

Crystallization of Galectin-8 Linker Reveals Intricate Relationship between the N-terminal Tail and the Linker.

Galectin-8 (Gal-8) plays a significant role in normal immunological function as well as in cancer. This lectin contains two carbohydrate recognition domains (CRD) connected by a peptide linker. The N-terminal CRD determines ligand binding specificity, whereas the linker has been proposed to regulate overall Gal-8 function, including multimerization and biological activity. Here, we crystallized the Gal-8 N-terminal CRD with the peptide linker using a crystallization condition that contains Ni2+. The Ni2+ ion was found to be complexed between two CRDs via crystal packing contacts. The coordination between Ni2+ and Asp25 plays an indirect role in determining the structure of ß-strand F0 and in influencing the linker conformation which could not be defined due to its dynamic nature. The linker was also shortened in situ and crystallized under a different condition, leading to a higher resolution structure refined to 1.08 Å. This crystal structure allowed definition of a short portion of the linker interacting with the Gal-8 N-terminal tail via ionic interactions and hydrogen bonds. Observation of two Gal-8 N-terminal CRD structures implies that the N-terminal tail and the linker may influence each other's conformation. In addition, under specific crystallization conditions, glycerol could replace lactose and was observed at the carbohydrate binding site. However, glycerol did not show inhibition activity in hemagglutination assay.

[The strategies and research progresses of rational improvement of the yield of microbial drug- A review].

Microbial drug is a large family of small molecules with unusual structural features and potent bioactivities. The production of microbial drug is crucial for its subsequent development and cost. Traditional breeding strategies for microbial drug production have been demonstrated to be remarkably effective, but they have also indicated the drawback of exceptional randomness and high cost. Synthetic biology has recently promised a revival for the rational enhancement of microbial drugs. In this review, we mainly discuss the recent progress from the aspects of promoter engineering, precursor supply, genome shuffling and etc., to delineate the application of the synthetic biology strategies to enhance the production of the microbial drugs, particularly, produced by actinomycetes.

In vivo anticancer and immunomodulating activities of mannogalactoglucan-type polysaccharides from Lentinus edodes (Berkeley) Singer.

There is considerable interest in the potential of mushrooms in modulating the immune system and/or suppressing tumor growth. Among the studied bioactive compounds in mushrooms, polysaccharides are the most important. Nontoxic fungal polysaccharides have a more important role in immunomodulating and antitumor activities which are related to their effects to act of immune effecter cells such as lymphocytes, macrophages, dendritic cells, and natural killer cells involved in the innate and adaptive immunity. Two mannogalactoglucan-type polysaccharides (WPLE-N-2 and WPLE-A0.5-2), purified from the fruiting bodies of Lentinus edodes, were evaluated for their effects on the cellular immune response of Sarcoma 180 (S-180)-bearing mice. Mice were treated with 100 mg/kg body weight of the polysaccharides for 10 days. Significant tumor regressions of the polysaccharide groups' mice were observed compared to the control group. These polysaccharides could induce an increase in nitrite oxide (NO) production in peritoneal macrophages, significantly increase macrophage phagocytosis of tumor-bearing mice and augment concanavalin (ConA) and lipopolysaccharide (LPS)-induced splenocytes proliferation. Our results indicated that immunomodulating activity occurred through host mediation in response to lymphocyte proliferation, macrophage phagocytosis and induction of NO production while the antitumor activity occurred through direct cytotoxicity. Our findings suggest that mannogalactoglucan-type polysaccharides from L. edodes can be explored as novel potential immunostimulants. Our research provides essential data to a better understanding of L. edodes bioactive compounds, especially polysaccharides. Our results also confirm the key role of ß-linkages in the antitumor and immunomodulating effects of polysaccharides.

Association between serum copper levels and muscle mass: results from NHANES 2011-2016.

Copper is essential for various biological processes. However, excess copper has several adverse health effects. The effects of serum copper on muscle mass are poorly understood. This study aimed to investigate the association between serum copper levels and muscle mass in the US population. We utilized National Health and Nutrition Examination Survey (NHANES) data between 2011 and 2016 for analysis. Data on serum copper, muscle mass (measured using the appendicular skeletal muscle mass index (ASMI)), and covariates were extracted and analyzed. Weighted multivariate linear regression analyses and smooth curve fittings were performed to investigate the association between serum copper levels and ASMI. Subgroup analyses stratified according to age and sex were performed. In the presence of nonlinearity, threshold effect analysis was performed using a two-piecewise linear regression model. A total of 3860 participants were included in the final analysis. Serum copper levels were negatively associated with ASMI in the fully adjusted model. Furthermore, by comparing participants in the highest and lowest tertiles of serum copper levels, we found that the ASMI decreased by 0.292 kg/m2. In the sex-stratified subgroup analysis, we observed an inverse association between serum copper levels and the ASMI in both men and women. When stratified by age, the association remained significant among participants < 40 years of age, but not among those ≥ 40 years old. Smooth curve fitting revealed a nonlinear relationship between serum copper and ASMI, with an inflection point identified at 150.6 µg/dL. Our study revealed an inverse relationship between serum copper levels and muscle mass. This finding improves the current knowledge on the impact of serum copper on muscle loss and highlights the importance of serum copper homeostasis in muscle health.

Osiris17 is essential for stable integrin localization and function during insect wing epithelia remodeling.

The dynamic adhesion between cells and their extracellular matrix is essential for the development and function of organs. During insect wing development, two epithelial sheets contact each other at their basal sites through the interaction of ßPS integrins with the extracellular matrix. We report that Osiris17 contributes to the maintenance of ßPS integrins localization and function in developing wing of Drosophila and locust. In flies with reduced Osiris17 expression the epithelia sheets fail to maintain the integrity of basal cytoplasmic junctional bridges and basal adhesion. In contrast to the continuous basal integrin localization in control wings, this localization is disrupted during late stages of wing development in Osiris17 depleted flies. In addition, the subcellular localization revealed that Osiris17 co-localizes with the endosomal markers Rab5 and Rab11. This observation suggests an involvement of Osiris17 in endosomal recycling of integrins. Indeed, Osiris17 depletion reduced the numbers of Rab5 and Rab11 positive endosomes. Moreover, overexpression of Osiris17 increased co-localization of Rab5 and ßPS integrins and partially rescued the detachment phenotype in flies with reduced ßPS integrins. Taken together, our data suggest that Osiris17 is an endosome related protein that contributes to epithelial remodeling and morphogenesis by assisting basal integrins localization in insects.

Chitinase 6 is required for procuticle thickening and organ shape in Drosophila wing.

The polysaccharide chitin is a major scaffolding molecule in the insect cuticle. In order to be functional, both chitin amounts and chitin organization have been shown to be important parameters. Despite great advances in the past decade, the molecular mechanisms of chitin synthesis and organization are not fully understood. Here, we have characterized the function of the Chitinase 6 (Cht6) in the formation of the wing, which is a simple flat cuticle organ, in the fruit fly Drosophila melanogaster. Reduction of Cht6 function by RNA interference during wing development does not affect chitin organization, but entails a thinner cuticle suggesting reduced chitin amounts. This phenotype is opposed to the one reported recently to be caused by reduction of Cht10 expression. Probably as a consequence, cuticle permeability to xenobiotics is enhanced in Cht6-less wings. We also observed massive deformation of these wings. In addition, the shape of the abdomen is markedly changed upon abdominal suppression of Cht6. Finally, we found that suppression of Cht6 transcript levels influences the expression of genes coding for enzymes of the chitin biosynthesis pathway. This finding indicates that wing epidermal cells respond to activity changes of Cht6 probably trying to adjust chitin amounts. Together, in a working model, we propose that Cht6-introduced modifications of chitin are needed for chitin synthesis to proceed correctly. Cuticle thickness, according to our hypothesis, is in turn required for correct organ or body part shape. The molecular mechanisms of this processes shall be characterized in the future.

Pre-meiotic deletion of PEX5 causes spermatogenesis failure and infertility in mice.

Peroxisomes are involved in the regulation of various pathological processes. Peroxisomal biogenesis factor 5 (PEX5), which plays an essential role in peroxisomal biogenesis, is critical for reactive oxygen species (ROS) accumulation. However, its underlying functions in spermatogenesis have not yet been identified. Pex5 was deleted by crossing Stra8-Cre mice with Pex5flox/flox mice before the onset of meiosis. The morphology of testes and epididymides, spermatogenesis function, and fertility in both wild type (WT) and Pex5-/- mice were analysed by haematoxylin and eosin (HE) and immunofluorescent staining. Mechanism of PEX5 affecting peroxisomes and spermatogenesis were validated by Western blot and transmission electron microscopy (TEM). Transcriptome RNA sequencing (RNA-seq) was used to profile the dysregulated genes in testes from WT and Pex5-/- mice on postnatal day (P) 35. The adult Pex5 knockout male mice were completely sterile with no mature sperm production. Loss of Pex5 in spermatocytes resulted in multinucleated giant cell formation, meiotic arrest, abnormal tubulin expression, and deformed acrosome formation. Furthermore, Pex5 deletion led to delayed DNA double-strand break repair and improper crossover at the pachytene stage. Impaired peroxisome function in Pex5 knockout mice induced ROS redundancy, which in turn led to an increase in germ cell apoptosis and a decline in autophagy. Pex5 regulates ROS during meiosis and is essential for spermatogenesis and male fertility in mice.