The Arabidopsis GPI-anchored protein COBL11 is necessary for regulating pollen tube integrity

Pollen tube integrity is required for achieving double fertilization in angiosperms. The rapid alkalinization factor4/19-ANXUR1/2-Buddha's paper seal 1/2 (RALF4/19-ANX1/2-BUPS1/2)-complex-mediated signaling pathway is critical to maintain pollen tube integrity, but the underlying mechanisms regulating the polar localization and distribution of these complex members at the pollen tube tip remain unclear. Here, we find that COBRA-like protein 11 (COBL11) loss-of-function mutants display a low pollen germination ratio, premature pollen tube burst, and seed abortion in Arabidopsis. COBL11 could interact with RALF4/19, ANX1/2, and BUPS1/2, and COBL11 functional deficiency could result in the disrupted distribution of RALF4 and ANX1, altered cell wall composition, and decreased levels of reactive oxygen species in pollen tubes. In conclusion, COBL11 is a regulator of pollen tube integrity during polar growth, which is conducted by a direct interaction that ensures the correct localization and polar distribution of RALF4 and ANX1 at the pollen tube tip.

Multifaceted roles of LhWRKY44 in promoting anthocyanin accumulation in Asiatic hybrid lilies (Lilium spp.)

The Asiatic hybrid lily (Lilium spp.) is a horticultural crop with high commercial value and diverse anthocyanin pigmentation patterns. However, the regulatory mechanism underlying lily flower color has been largely unexplored. Here, we identified a WRKY transcription factor from lily tepals, LhWRKY44, whose expression was closely associated with anthocyanin accumulation. Functional verification indicated that LhWRKY44 positively regulated anthocyanin accumulation. LhWRKY44 physically interacted with LhMYBSPLATTER and directly bound to the LhMYBSPLATTER promoter, which enhanced the effect of the LhMYBSPLATTER-LhbHLH2 MBW complex activator on anthocyanin accumulation. Moreover, EMSA and dual-luciferase assays revealed that LhWRKY44 activated and bound to the promoters of gene LhF3H and the intracellular anthocyanin-related glutathione S-transferase gene LhGST. Interestingly, our further results showed that LhWRKY44 participated in light and drought-induced anthocyanin accumulation, and improved the drought tolerance in lily via activating stress-related genes. These results generated a multifaceted regulatory mechanism for the LhWRKY44-meditaed enhancement by the environmental signal pathway of anthocyanin accumulation and expanded our understanding of the WRKY-mediated transcriptional regulatory hierarchy modulating anthocyanin accumulation in Asiatic hybrid lilies.

A Na+/H+ antiporter-encoding salt overly sensitive 1 gene, LpSOS1, involved in positively regulating the salt tolerance in Lilium pumilum

Lilium pumilum has a strong salt tolerance. However, the molecular mechanism underlying its salt tolerance remains unexplored. Here, LpSOS1 was cloned from L. pumilum and found to be significantly enriched at high NaCl concentrations (100 mM). In tobacco epidermal cells, localization analysis showed that the LpSOS1 protein was primarily located in the plasma membrane. Overexpression of LpSOS1 resulted in up-regulation of salt stress tolerance in Arabidopsis, as indicated by reduced malondialdehyde levels and Na⁺/K⁺ ratio, and increased activity of antioxidant reductases (including superoxide dismutase, peroxidase, and catalase). Treatment with NaCl resulted in improved growth, as evidenced by increased biomass, root length, and lateral root growth, in both sos1 mutant (atsos1) and wild-type (WT) Arabidopsis plants that overexpressed LpSOS1,Under NaCl treatment,atsos1 and WT Arabidopsis plants overexpressing LpSOS1 exhibited better growth, with higher biomass, root length, and lateral root quantity, whereas in the absence of LpSOS1 overexpression, the plants of both lines were wilted and chlorotic and even died under salt stress. When exposed to salt stress, the expression of stress-related genes was notably upregulated in the LpSOS1 overexpression line of Arabidopsis as compared to the WT. Our findings indicate that LpSOS1 enhances salt tolerance in plants by regulating ion homeostasis, reducing Na⁺/K⁺ ratio, thereby protecting the plasma membrane from oxidative damage caused by salt stress, and enhancing the activity of antioxidant enzymes. Therefore, the increased salt tolerance conferred by LpSOS1 in plants makes it a potential bioresource for breeding salt-tolerant crops. Further investigation into the mechanisms underlying lily's resistance to salt stress would be advantageous and could serve as a foundation for future molecular improvements.

Invasive fungal infection is associated with antibiotic exposure in preterm infants: a multi-centre prospective case-control study

BACKGROUND

Previous antibiotic exposure is an important risk factor for invasive fungal infection (IFI). Antibiotic overexposure is common in lower-income countries; however, multi-centre studies concerning IFI in relation to antibiotic exposure are scarce.

AIM

This prospective, multi-centre matched case-control study explored the correlation of IFI and antibiotic exposure in very preterm infants or very-low-birthweight infants admitted to 23 tertiary hospitals in China between 2018 and 2021.

METHODS

Using a 1:2 matched design for gestational age, birth weight and early-onset sepsis (yes/no), the risk factors between infants diagnosed with IFI and infection-free controls were compared. The antibiotic use rate (AUR) was calculated using calendar days of antibiotic therapy in the 4 weeks preceding IFI onset divided by onset day of IFI.

FINDINGS

In total, 6368 infants were included in the study, of which 90 (1.4%) were diagnosed with IFI. Median AUR, length of antibiotic therapy (LOT) and days of antibiotic therapy (DOT) within the 4 weeks preceding IFI onset were 0.90, 18 days and 30 days, respectively. Multi-variate analysis showed that a 10% increase in AUR, each additional day of DOT and LOT, and each additional day of third-generation cephalosporins and carbapenems were notably associated with IFI.

CONCLUSION

Prolonged antibiotic therapy is common before the onset of IFI, and is an important risk factor, especially the use of third-generation cephalosporins and carbapenems. Antibiotic stewardship should be urgently developed and promoted for preterm infants in order to reduce IFI in lower-income countries such as China.

The phospholipid flippase ALA3 regulates pollen tube growth and guidance in Arabidopsis

Pollen tube guidance regulates the growth direction and ovule targeting of pollen tubes in pistils, which is crucial for the completion of sexual reproduction in flowering plants. The Arabidopsis (Arabidopsis thaliana) pollen-specific receptor kinase (PRK) family members PRK3 and PRK6 are specifically tip-localized and essential for pollen tube growth and guidance. However, the mechanisms controlling the polar localization of PRKs at the pollen tube tip are unclear. The Arabidopsis P4-ATPase ALA3 helps establish the polar localization of apical phosphatidylserine (PS) in pollen tubes. Here, we discovered that loss of ALA3 function caused pollen tube defects in growth and ovule targeting and significantly affected the polar localization pattern of PRK3 and PRK6. Both PRK3 and PRK6 contain two polybasic clusters in the intracellular juxtamembrane domain, and they bound to PS in vitro. PRK3 and PRK6 with polybasic cluster mutations showed reduced or abolished binding to PS and altered polar localization patterns, and they failed to effectively complement the pollen tube-related phenotypes of prk mutants. These results suggest that ALA3 influences the precise localization of PRK3, PRK6, and other PRKs by regulating the distribution of PS, which plays a key role in regulating pollen tube growth and guidance.

WUSCHEL-related homeobox genes cooperate with cytokinin to promote bulbil formation in Lilium lancifolium

The bulbil is an important vegetative reproductive organ in triploid tiger lily (Lilium lancifolium). Based on our previously obtained transcriptome data, we screened two WUSCHEL-related homeobox (WOX) genes closely related to bulbil formation, LlWOX9 and LlWOX11. However, the biological functions and regulatory mechanisms of LlWOX9 and LlWOX11 are unclear. In this study, we cloned the full-length coding sequences of LlWOX9 and LlWOX11. Transgenic Arabidopsis (Arabidopsis thaliana) showed increased branch numbers, and the overexpression of LlWOX9 and LlWOX11 in stem segments promoted bulbil formation, while the silencing of LlWOX9 and LlWOX11 inhibited bulbil formation, indicating that LlWOX9 and LlWOX11 are positive regulators of bulbil formation. Cytokinin type-B response regulators could bind to the promoters of LlWOX9 and LlWOX11 and promote their transcription. LlWOX11 could enhance cytokinin pathway signaling by inhibiting the transcription of type-A LlRR9. Our study enriches the understanding of the regulation of plant development by the WOX gene family and lays a foundation for further research on the molecular mechanism of bulbil formation in lily.

Construction of yeast one-hybrid library and screening of transcription factors regulating LhMYBSPLATTER expression in Asiatic hybrid lilies (Lilium spp.)

BACKGROUND

Anthocyanins, which belong to flavonoids, are widely colored among red-purple pigments in the Asiatic hybrid lilies (Lilium spp.). Transcription factor (TF) LhMYBSPLATTER (formerly known as LhMYB12-Lat), identified as the major kernel protein, regulating the anthocyanin biosynthesis pathway in 'Tiny Padhye' of Tango Series cultivars, which the pigmentation density is high in the lower half of tepals and this patterning is of exceptional ornamental value. However, the research on mechanism of regulating the spatial and temporal expression differences of LhMYBSPLATTER, which belongs to the R2R3-MYB subfamily, is still not well established. To explore the molecular mechanism of directly related regulatory proteins of LhMYBSPLATTER in the anthocyanin pigmentation, the yeast one-hybrid (Y1H) cDNA library was constructed and characterized.

RESULTS

In this study, we describe a yeast one-hybrid library to screen transcription factors that regulate LhMYBSPLATTER gene expression in Lilium, with the library recombinant efficiency of over 98%. The lengths of inserted fragments ranged from 400 to 2000 bp, and the library capacity reached 1.6 × 10⁶ CFU of cDNA insert, which is suitable to fulfill subsequent screening. Finally, seven prey proteins, including BTF3, MYB4, IAA6-like, ERF4, ARR1, ERF WIN1-like, and ERF061 were screened by the recombinant bait plasmid and verified by interaction with the LhMYBSPLATTER promoter. Among them, ERFs, AUX/IAA, and BTF3 may participate in the negative regulation of the anthocyanin biosynthesis pathway in Lilium.

CONCLUSION

A yeast one-hybrid library of lily was successfully constructed in the tepals for the first time. Seven candidate TFs of LhMYBSPLATTER were screened, which may provide a theoretical basis for the study of floral pigmentation.

An ultrasensitive ratiometric immunosensor based on the ratios of conjugated distyrylbenzene derivative nanosheets with AIECL properties and electrochemical signal for CYFRA21-1 detection

Aggregation-induced electrochemiluminescence reagent, a distyrylbenzene derivative with donor-acceptor conjugated nanosheet structure, namely TPAPCN, was used as a trace label and modified on the electrode through the formation of classical sandwich complex of antibody-antigen-antibody in this work. In aggregate state, TPAPCN with twisted structure was limited in nanometer space through intermolecular π - π stacking interactions, which not only restricts the intramolecular motions but also combines a large number of singlet excitons to greatly trigger electrochemiluminescence (ECL). The ECL signal of this system enhanced with more captured cytokeratin 19 fragment 21-1 (CYFRA21-1) on the modified electrode. Three-dimensional graphene/platinum nanoparticles with large specific surface, and excellent electroconductivity and biocompatibility were prepared and acted as excellent carriers for thionine handling (3D-GN/PtNPs/Th), which was employed for improving the loading of antibodies and generating internal electrochemical signal. Consequently, a novel ratiometric sandwich immunosensor for CYFRA21-1 detection was fabricated based on TPAPCN and 3D-GN/PtNPs/Th, that is, a rapid and reliable detection was achieved through the ratio between ECL and electrochemical signals. The prepared sensor performed good linearity in the range of 50 fg/mL to 1 ng/mL with a detection limit as low as 16 fg/mL. Moreover, the detection results revealed well in the analysis of human serum samples, demonstrating a significant application for clinical monitoring and biomolecules detection.

Chrysanthemum WRKY15-1 promotes resistance to Puccinia horiana Henn. via the salicylic acid signaling pathway

Chrysanthemum white rust disease, which is caused by the fungus Puccinia horiana Henn., severely reduces the ornamental quality and yield chrysanthemum. WRKY transcription factors function in the disease-resistance response in a variety of plants; however, it is unclear whether members of this family improve resistance to white rust disease in chrysanthemum. In this study, using PCR, we isolated a WRKY15 homologous gene, CmWRKY15-1, from the resistant chrysanthemum cultivar C029. Real-time quantitative PCR (RT-qPCR) revealed that CmWRKY15-1 exhibited differential expression patterns between the immune cultivar C029 and the susceptible cultivar Jinba upon P. horiana infection. In addition, salicylic acid (SA) treatment strongly induced CmWRKY15-1 expression. Overexpression of CmWRKY15-1 in the chrysanthemum-susceptible cultivar Jinba increased tolerance to P. horiana infection. Conversely, silencing CmWRKY15-1 via RNA interference (RNAi) in C029 increased sensitivity to P. horiana infection. We also determined that P. horiana infection increased both the endogenous SA content and the expression of salicylic acid biosynthesis genes in CmWRKY15-1-overexpressing plants, whereas CmWRKY15-1 RNAi plants exhibited the opposite effects under the same conditions. Finally, the transcript levels of pathogenesis-related (PR) genes involved in the SA pathway were positively associated with CmWRKY15-1 expression levels. Our results demonstrated that CmWRKY15-1 plays an important role in the resistance of chrysanthemum to P. horiana by influencing SA signaling.

Silencing of ATPase family AAA domain-containing protein 2 inhibits migration and invasion of colorectal cancer cells

Colorectal cancer is one of the most common malignant tumors with a high rate of distant metastasis, postoperative recurrence and mortality. ATPase family AAA domain-containing protein 2 (ATAD2), a member of ATPase family, is highly expressed in various cancers, including colorectal cancer. However, whether ATAD2 plays a role in the migration and invasion of colorectal cancer cells remains unknown. In this study, we established ATAD2 knockdown in colorectal cancer cell lines by RNA interference and found that silencing of ATAD2 inhibited the migration and invasion ability of Caco-2 and SW-480 cells. Moreover, ATAD2 silencing suppressed epithelial-mesenchymal transition (EMT), and reduced the expression and enzymatic activity of matrix metalloproteinases (MMPs) in Caco-2 and SW-480 cells. In summary, our results suggest that silencing of ATAD2 inhibits migration and invasion of colorectal cancer cells by suppressing EMT and decreasing the activity of MMPs. Hence, ATAD2 could be considered as a novel molecular marker of metastatic colorectal cancer, and it may provide new insights for clinical diagnosis and treatment of colorectal cancer.

Correlations of MC4R and MSH2 expression with obesity in colon cancer patients

OBJECTIVE

To investigate the correlations of MC4R and MSH2 with adult obesity, a total of 46 patients with early-stage colon cancer were treated in our hospital between February 2008 and February 2009 and were enrolled.

PATIENTS AND METHODS

Venous blood was regularly drawn from subjects of the observation group and 48 healthy subjects for 6 years. Expression levels of MC4R and MSH2 genes were tested using quantitative polymerase chain reaction analyses, and the ensuing proteins were determined using enzyme-linked immunosorbent assays and Western blotting and immunohistochemical analyses. Finally, correlations with body mass index (BMI) and the presence of colon cancer were identified using multivariate analyses.

RESULTS

Compared with the control group, MSH2 mRNA and protein expression increased significantly over time (p < 0.05) in patients with colon cancer. Moreover, MSH2 expression was correlated with colon cancer progression, and MC4R mRNA and protein expression increase concurrently in comparison with the control group (p < 0.05). Also, the mean BMI among patients with colon cancer was 30.8, whereas that among control subjects was only 21.4. These data indicate a relationship between BMI and colon cancer.

CONCLUSIONS

Expression of MSH2 in patients with colon cancer may promote the expression of the obesity gene MC4R, potentially contributing to body weight gains.

Defective expression of regulatory B cells in iodine-induced autoimmune thyroiditis in non-obese diabetic H-2(h4) mice

INTRODUCTION

The ability of B cells to negatively regulate cellular immune responses and inflammation has been described. The regulatory B (Breg) cells with the unique CD1d(hi)CD5(+)CD19(+) phenotype and the capacity to produce IL-10 are potent negative regulators of inflammation and autoimmunity in several in vivo mouse models of autoimmune disease.

AIM

To investigate whether Breg cell deficiency participates in autoimmune thyroiditis (AIT) in an animal model.

MATERIALS AND METHODS

Non-obese diabetic (NOD).H-2(h4) mice at 4 weeks of age were randomly divided into control and iodine-treated groups; the iodine-treated group received sterile water containing 0.005 % NaI for 10 or 20 weeks. The percentage of CD1d(hi)CD5(+)CD19(+) Bregs, CD4(+)CD25(+)FoxP3(+) regulatory T cells (Treg) and CD4(+)IL17(+) T helper 17 cells (Th17) in splenic mononuclear cells was detected by multicolor flow cytometry. The expression of IL-10 mRNA and TGF-β mRNA in splenocytes was measured by real-time RT-PCR.

RESULTS

NOD.H-2(h4) mice spontaneously develop anti-thyroglobulin autoantibodies and intrathyroidal lymphocyte infiltration when supplied with iodine in drinking water. Mice with AIT had a decreased CD1d(hi)CD5(+)CD19(+) Breg subset and reduced IL-10 mRNA expression in splenocytes compared with controls (p < 0.05) and maintained relatively low levels during the development of thyroiditis. The proportion of Breg cells was negatively correlated with the proportion of Th17 cells, but positively correlated with CD4(+)CD25(+)FoxP3(+) Treg cells in splenocytes (All p < 0.05).

CONCLUSIONS

The defective expression of Breg cells combined with impaired Treg cells and enhanced Th17 cells might play an important role in the development of iodine-induced AIT in NOD.H-2(h4) mice.

Heterogeneous processing and zona pellucida binding activity of pig zonadhesin

Zonadhesin is a mosaic protein in sperm membrane fractions that binds directly and in a species-specific manner to the extracellular matrix (zona pellucida) of the oocyte. The active form of pig zonadhesin from capacitated, epididymal spermatozoa comprises two covalently associated polypeptide chains of M(r) 105,000 (p105) and M(r) 45,000 (p45). Here we report detection and characterization of multiple zonadhesin isoforms in freshly ejaculated cells. Antibodies to the predicted von Willebrand D0-D1, D1, and D3 domains of pig zonadhesin recognized p105, p45, and additional M(r) 60,000-90,000 polypeptides in particulate fractions of uncapacitated cells. Although the p105/45 form constituted a minority of all zonadhesin forms in sperm membrane fractions, it was the predominant form capable of binding to the pig zona pellucida. Zonadhesin-binding sites were distributed over the entire zona pellucida. Anion exchange chromatography resolved active, p105/45 zonadhesin from the p60-90 inactive forms. Without disulfide bond reduction some zonadhesin was M(r) > or = 300,000, including M(r) 300,000 and 900,000 proteins comprising in part multimers of p105/45. The multimeric forms did not bind the zona pellucida as avidly as did the p105/45 monomer. Expressed D1 and D3 domain fragments containing the CG(L/V)CG sequence motif spontaneously formed multimers at -246 mV E(h) in vitro. Double Cys --> Ser mutants of the D1 fragment formed multimers with the same apparent kinetics as the wild type protein. Zonadhesin localized to the apical head of pig spermatozoa. We conclude that a heterogeneous combination of specific proteolysis and intermolecular disulfide bond formation in the sperm head generates multiple forms of zonadhesin with differing avidities for the zona pellucida.

Stability of luteinizing hormone releasing hormone: effects of pH, temperature, pig skin, and enzyme inhibitors

The purpose of this investigation was to determine the stability of luteinizing hormone releasing hormone (LHRH) as a function of solution pH, temperature, and pig skin with and without enzyme inhibitors. LHRH, incubated with a 0.1 M phosphate buffer (pH 2.5-8.1), pig skin, and pig skin with enzyme inhibitors, was analyzed using reversed-phase high performance liquid chromatography. The solution's pH affected the rate constants of LHRH, following apparent first-order kinetics. Maximum stability was achieved at pH 6.05. Therefore, the effect of various temperatures (i.e., 65, 75, 80, and 90 degrees C) was studied on the stability of LHRH at pH 6.05. The activation energy for the overall reaction was 23.4 kcal/mol at pH 6.05. The shelf-life of LHRH at 25 degrees C and pH 6.05, calculated using the Arrhenius equation, was approximately 4 years. The rate constant of LHRH in the skin (area: 9 cm2; thickness: 0.5 mm) was 0.167 hr-1. Out of three inhibitors (i.e., aprotinin, bestatin, and leupeptin), bestatin had the best stabilizing effect on the degradation of LHRH by the skin. The rate constant of LHRH in the presence of bestatin was 0.082 hr-1. Sixty percent of LHRH was found to be degraded in the skin within 5 hr in the absence of enzyme inhibitors, whereas only 33% of LHRH was degraded in the presence of bestatin (an aminopeptidase inhibitor).

Application of solid-phase microextraction to the recovery of explosives and ignitable liquid residues from forensic specimens

A current review of the application of solid-phase microextraction (SPME) to the analysis of ignitable liquids and explosive residues is presented along with experimental results demonstrating the relative effects of controllable variables. Variables discussed include fiber chemistry, adsorption and desorption temperatures, extraction and desorption times, fiber sampling placement (direct, headspace, and partial headspace) and matrix effects, including water content. SPME is shown to be an inexpensive, rapid and sensitive method for the analysis of ignitable liquids and high explosives residues from solid debris samples and from aqueous samples. Explosives are readily detected at parts per trillion concentrations and ignitable liquids are reproducibly detected at levels below those using conventional methods.

Effect of buffer pH, buffer concentration and skin with or without enzyme inhibitors on the stability of [Arg(8)]-vasopressin

The stability of [Arg(8)]-vasopressin (AVP) as a function of buffer pH, buffer concentration, salt concentration, temperature, and skin with and without enzyme inhibitors was investigated. AVP was analyzed by reverse-phase high-performance liquid chromatography. The results indicated that the buffer's pH affected the degradation rate of AVP. Buffer ions (H(2)PO(4)(-) and HPO(4)(2-)) and salt concentrations had no effect on the degradation of AVP. Maximum stability was achieved at pH 3.35 among pH values tested. The activation energy for the overall reaction was 21.5 kcal mol(-1) at pH 3.35. From the Arrhenius equation, the shelf-life of AVP at 25 degrees C and pH 3.35 was calculated to be 1.38 years. The degradation rate of AVP in the skin (area: 9 cm(2), thickness: 0.5 mm) was 0.22 h(-1). Bestatin (an aminopeptidase inhibitor) had the best stabilizing effect on the degradation of AVP by skin among the three enzyme inhibitors (i.e. aprotinin, bestatin, and leupeptin) studied. The degradation rate of AVP in the skin was reduced to 0. 059 h(-1) in the presence of bestatin in comparison with no inhibitor (0.22 h(-1)).

[Determination of trace arsenic using GFAAS with metal-coated graphite tube]

The sensitivity, precision and disturbance-resisting property were studied by using metal-coated graphite tube for electrically heated atomic absorption spectrometry. The surface characteristic of the metal-coated graphite tube was studied by using X-ray diffraction meter and scanning electron microscope. The mechanism of satisfactory performance was discussed.