Binding interaction of a ring-hydroxylating dioxygenase with fluoranthene in Pseudomonas aeruginosa DN1

Pseudomonas aeruginosa DN1 can efficiently utilize fluoranthene as its sole carbon source, and the initial reaction in the biodegradation process is catalyzed by a ring-hydroxylating dioxygenase (RHD). To clarify the binding interaction of RHD with fluoranthene in the strain DN1, the genes encoding alpha subunit (RS30940) and beta subunit (RS05115) of RHD were functionally characterized through multi-technique combination such as gene knockout and homology modeling as well as molecular docking analysis. The results showed that the mutants lacking the characteristic alpha subunit and/or beta subunit failed to degrade fluoranthene effectively. Based on the translated protein sequence and Ramachandran plot, 96.5% of the primary amino-acid sequences of the alpha subunit in the modeled structure of the RHD were in the permitted region, 2.3% in the allowed region, but 1.2% in the disallowed area. The catalytic mechanism mediated by key residues was proposed by the simulations of molecular docking, wherein the active site of alpha subunit constituted a triangle structure of the mononuclear iron atom and the two oxygen atoms coupled with the predicted catalytic ternary of His217-His222-Asp372 for the dihydroxylation reaction with fluoranthene. Those amino acid residues adjacent to fluoranthene were nonpolar groups, and the C7-C8 positions on the fluoranthene ring were estimated to be the best oxidation sites. The distance of C7-O and C8-O was 3.77 Å and 3.04 Å respectively, and both of them were parallel. The results of synchronous fluorescence and site-directed mutagenesis confirmed the roles of the predicted residues during catalysis. This binding interaction could enhance our understanding of the catalytic mechanism of RHDs and provide a solid foundation for further enzymatic modification.

Transcriptome analysis reveals the molecular mechanism of yield increases in maize under stable soil water supply

This study explored the physiological and molecular mechanisms of yield increase in maize under stable soil water content (SW) conditions. Results of the study showed that under SW conditions, corn yield increased by 38.72 and 44.09% in 2019 and 2020, respectively. Further, it was found that dry matter accumulation, economic coefficient and photosynthetic rate also increased by 31.24 and 25.67%, 5.45 and 15.38% as well as 29.60 and 31.83% in 2019 and 2020 respectively. However, the results showed that both the activity of antioxidant enzymes and content of osmotic adjustment substances decreased in maize under SW conditions. When compared with soil moisture content of dry and wet alternation (DW) conditions, SW could not only significantly promote growth and yield of maize but also increase the economic coefficient. Transcriptome profiles of maize leaves under the two conditions (SW and DW) were also analyzed and compared. It was found that 11 genes were highly up-regulated in the photosynthesis pathway. These genes included photosystem II protein V (PsbE), photosystem II protein VI (PsbF), photosystem II protein D1 (PsbA), photosystem II protein D2 (PsbD) and ATP synthase CF1 beta subunit (atpB). Further, it was found that four genes were up-regulated in the oxidative phosphorylation pathway., These were ATP synthase CF1 epsilon subunit (atpE), ATP synthase CF1 beta subunit (atpB), NADH dehydrogenase subunit 4L (ndhE) and NADH dehydrogenase subunit 6 (ndhG). In conclusion, the physiological mechanism of stable soil water content (SW) to increase corn yield may be the enhancement of photosynthetic capacity and energy metabolism.

Ectopic pregnancy: difficulties of timely diagnosis

Ectopic pregnancy is an important medical and social problem that threatens not only the reproductive function of women, but also her life. The frequency of ectopic pregnancy does not tend to decrease, however, high alertness with regard to this pathology, an integrated approach to diag-nosis, including the study of clinical data, ultrasound examination, as well as monitoring the level of beta-subunit of chorionic gonadotropin in blood serum, has significantly reduced the maternal mortality rate due to this pathology. At the same time, the existing modern methods of treat-ment make it possible to do without radical operations and preserve the reproductive function of patients.

Differential expression of potassium calcium-activated channel subfamily M regulatory beta subunit 1 in human epithelial ovarian cancer.

Epithelial ovarian cancer (EOC) is the most lethal gynecologic cancer (1). We performed discovery of genes associated with epithelial ovarian cancer and of the high-grade serous ovarian cancer (HGSC) subtype, using published and public microarray data (2, 3) to compare global gene expression profiles of normal ovary or fallopian tube with that of primary tumors from women diagnosed with epithelial ovarian cancer or HGSC. We identified the gene encoding potassium calcium-activated channel subfamily M regulatory beta subunit 1, KCNMB1, as among the genes whose expression was most different in epithelial ovarian cancer as compared to the normal fallopian tube. KCNMB1 expression was significantly lower in high-grade serous ovarian tumors relative to normal fallopian tube. KCNMB1 expression correlated with progression-free survival in patients p53 mutant with ovarian cancer. These data indicate that expression of KCNMB1 is perturbed in epithelial ovarian cancers broadly and in ovarian cancers of the HGSC subtype. KCNMB1 may be relevant to pathways underlying ovarian cancer initiation (transformation) or progression.

Identification and characterization of pleiotropic high-persistence mutations in the beta subunit of the bacterial RNA polymerase

Mutations conferring resistance to bactericidal antibiotics reduce average susceptibility of the mutant populations. It is unknown, however, how those mutations affect survival of individual bacteria. Since surviving bacteria can be a reservoir for recurring infections, it is important to know how survival rates may be affected by resistance mutations and by the choice of antibiotics. Here we present the evidence that: i) Escherichia coli mutants with 100-1000 times increased frequency of survival in ciprofloxacin, an archetypal fluoroquinolone antibiotic, can be readily obtained in a stepwise selection; ii) the high survival frequency is conferred by mutations in the switch region of the beta subunit of the RNA polymerase; iii) the switch-region mutations are (p)ppGpp mimics, partially analogous to rpoB stringent mutations; iv) the stringent and switch-region rpoB mutations frequently occur in clinical isolates of E. coli , Acinetobacter baumannii , Mycobacterium tuberculosis and Staphylococcus aureus , and at least one of them, RpoB S488L, which is a common rifampicin-resistance mutations, dramatically increases survival of a clinical MRSA strain in ampicillin; v) the RpoB-associated high-survival phenotype can be reversed by sub-inhibitory concentrations of chloramphenicol.

Leptin Modulates the mRNA Expression of Follicle Development Markers in Post-hatch Chicks in an Age-Dependent Manner

Leptin is involved in regulating reproductive function in chickens, and the development of the leptin system is initiated during the early embryonic stage; however, whether leptin has a specific role in regulating the ovarian development in early post-hatch days is still not fully understood. This study investigated the expression of ovarian functional markers in growing juvenile chickens, along with the effects of leptin on gene expression in the hypothalamus–pituitary–gonadal (HPG) axis on specific ovarian-remodeling days. Leptin receptor (LEPR), follicle-stimulating hormone receptor (FSHR), and the mRNA expression of aromatase (CYP19A1) tended to increase with age in the ovaries of growing chicks. In the ovaries of 7-day-old chicks, intraperitoneally injected leptin significantly increased the mRNA expressions of LEPR, FSHR, and CYP19A1, and this resulted in the increased serum estradiol levels. However, leptin had no effect on hypothalamic LEPR, gonadotropin-releasing hormone 1 (GnRH1), or gonadotropin-inhibitory hormone (GnIH) mRNAs; however, in the pituitary gland, leptin significantly increased the mRNA expression of luteinizing hormone beta subunit (LHB) but had no effect on the mRNA expression of follicle-stimulating hormone beta subunit (FSHB). In 28-day-old chicks, hypothalamic and pituitary mRNAs were unaffected by leptin administration, except hypothalamic LEPR mRNA that was upregulated by a high dose of leptin. In the ovary, leptin dose-dependently decreased the mRNA expression of LEPR; low doses of leptin significantly increased the mRNA expression of FSHR, whereas high doses significantly decreased this expression; leptin did not affect the mRNA expression of CYP19A1; and high leptin doses significantly reduced the serum estradiol levels. Collectively, the results of this study show that leptin modulates ovarian development and folliculogenesis marker genes by primarily acting on ovaries on the specific ovarian-remodeling days in post-hatch chicks, which may alter folliculogenesis and ovarian development toward puberty in chicken.

Binding Interaction of a Ring-hydroxylating Dioxygenase with Fluoranthene in Pseudomonas aeruginosa DN1

Pseudomonas aeruginosa DN1 can efficiently utilize fluoranthene as its sole carbon source, and the first step in the biodegradation process is catalyzed by a ring-hydroxylating dioxygenase (RHD). To better understand the binding interaction of RHD with fluoranthene in the strain DN1, the genes encoding alpha subunit (RS30940) and beta subunit (RS05115) of the RHD were functionally characterized using gene knockout approach and homology modeling combined with molecular docking. The results showed that the mutants lacking the characteristic alpha subunit and/or beta subunit failed to degrade fluoranthene effectively. Based on the translated protein sequence and Ramachandran plot, 96.5 % of the primary amino-acid sequences of the alpha subunit in the modeled structure of the RHD were in the permitted region, 2.3 % in the allowed region, but 1.2 % in the disallowed area. The active center of the alpha subunit constituted a triangle structure of the mononuclear iron atom and the two oxygen atoms coupled with a catalytic ternary of His217-His222-Asp372 for the dihydroxylation reaction with fluoranthene. Amino acid residues adjacent to fluoranthene were nonpolar groups, and the C7-C8 positions on the fluoranthene ring were estimated to be the best oxidation sites. The distance of C7-O and C8-O was 3.77 Å and 3.04Å respectively, and both of them were parallel. The results demonstrated that the dihydroxylation reaction was initiated at C7-C8 positions of the fluoranthene ring by RHD in P. aeruginosa DN1, indicating that the binding interaction may be useful for predicting substrate conversion of RHDs.