Multikink quantile regression for longitudinal data with application to progesterone data analysis

Motivated by investigating the relationship between progesterone and the days in a menstrual cycle in a longitudinal study, we propose a multikink quantile regression model for longitudinal data analysis. It relaxes the linearity condition and assumes different regression forms in different regions of the domain of the threshold covariate. In this paper, we first propose a multikink quantile regression for longitudinal data. Two estimation procedures are proposed to estimate the regression coefficients and the kink points locations: one is a computationally efficient profile estimator under the working independence framework while the other one considers the within-subject correlations by using the unbiased generalized estimation equation approach. The selection consistency of the number of kink points and the asymptotic normality of two proposed estimators are established. Second, we construct a rank score test based on partial subgradients for the existence of the kink effect in longitudinal studies. Both the null distribution and the local alternative distribution of the test statistic have been derived. Simulation studies show that the proposed methods have excellent finite sample performance. In the application to the longitudinal progesterone data, we identify two kink points in the progesterone curves over different quantiles and observe that the progesterone level remains stable before the day of ovulation, then increases quickly in 5 to 6 days after ovulation and then changes to stable again or drops slightly.     

LEP and LEPR are possibly a double-edged sword for wound healing

Wound healing is a complex and error-prone process. Wound healing in adults often leads to the formation of scars, a type of fibrotic tissue that lacks skin appendages. Hypertrophic scars and keloids can also form when the wound-healing process goes wrong. Leptin (Lep) and leptin receptors (LepRs) have recently been shown to affect multiple stages of wound healing. This effect, however, is paradoxical for scarless wound healing. On the one hand, Lep exerts pro-inflammatory and profibrotic effects; on the other hand, Lep can regulate hair follicle growth. This paper summarises the role of Lep and LepRs on cells in different stages of wound healing, briefly introduces the process of wound healing and Lep and LepRs, and examines the possibility of promoting scarless wound healing through spatiotemporal, systemic, and local regulation of Lep levels and the binding of Lep and LepRs.     

Evaluation of housekeeping genes as references for quantitative real-time PCR analysis of European eel,Anguilla anguilla

Eels are important aquaculture species for which an increasing number of reference genes are being identified and applied. In this study, five housekeeping genes [RPL7 (ribosomal protein L7), 18 S (18 S ribosomal RNA), EF1A (elongation factor 1α), ACTB (β-actin) and GAPDH (glyceraldehyde-3-phosphate dehydrogenase)] were chosen to evaluate their reliability as reference genes for quantitative real-time PCR (qPCR) for the study of Anguilla anguilla. The expression of the selected genes in different eel tissues was determined using qPCR at different growth stages or upon challenge by Anguillid herpesvirus (AngHV), and the expression levels of these genes were then compared and evaluated using the geNorm and NormFinder algorithms. Then, RefFinder was used to comprehensively rank the examined housekeeping genes. Interestingly, the expression of the evaluated housekeeping genes exhibited tissue-dependent and treatment-dependent variations. In different growth periods A. anguilla tissues, the most stable genes were the following: ACTB in mucus; 18 S in skin and kidney; RPL7 in muscle, gill, intestine and brain; EF1A in heart and liver; and GAPDH in spleen. In contrast, in AngHV-challenged A. anguilla tissues, the most stable genes were the following: 18 S in mucus; RPL7 in skin, gill, heart, spleen, kidney and intestine; EF1A in muscle and liver; and ACTB in brain. Further comparison analysis indicated that the expression of RPL7 and EF1A was stable in multiple A. anguilla tissues in different growth periods and in eels challenged by AngHV. Nonetheless, the expression level of GAPDH in eel tissues was lower, and it was unstable in several tissues. These results indicated that the selection of reference genes for qPCR analysis in A. anguilla should be made in accordance with experimental parameters, and both RPL7 and EF1A could be used as reference genes for qPCR study of A. anguilla at different growth stages or upon challenge by AngHV. The reference genes identified in this study could improve the accuracy of qPCR data and facilitate further studies aimed at understanding the biology of eels.     

Three-dimensional structures of the central regulatory proteins of the bacterial phosphotransferase system,HPr and enzyme IIAglc

Enzyme IIA and HPr are central regulatory proteins of the bacterial phosphoenolpyruvate:sugar phosphotransferase (PTS) system. Three-dimensional structures of the glucose enzyme IIA domain (IIA^glc) and HPr of Bacillus subtilis and Escherichia coli have been studied by both X-ray crystallography and Nuclear Magnetic Resonance (NMR) Spectroscopy. Phosphorylation of HPr of B. subtilis and IIA^glc of E. coli have also been characterized by NMR spectroscopy. In addition, the binding interfaces of B. subtilis HPr and IIA^glc have been identified from backbone chemical shift changes. This paper reviews these recent advances in the understanding of the three-dimensional structures of HPr and IIA^glc and their interaction with each other. © 1993 Wiley-Liss, Inc.     

Effects of ROS and caspase-3-like protein on the growth and aerenchyma formation of Potamogeton perfoliatus stem

Protoplasma - Aerenchyma formation plays an important role in the survival of Potamogeton perfoliatus in submerged environment. To understand the regulatory role of reactive oxygen species (ROS)...     

Comment on “Is Yuan in China’s Three Gorges a Gibbon or a Langur?”

International Journal of Primatology -     

β-Cyclodextrin-Based Nitrosoglutathione Improves the Storage Quality of Peach by Regulating the Metabolism of Endogenous Nitric Oxide,Hydrogen Sulfide,and Phenylpropane

Nitrosoglutathione (GSNO) and β-cyclodextrin (β-CD) exhibit positive roles in regulating fruit quality. However, there are few reports about the effects of GSNO and β-CD on enhancing storability and boosting nitric oxide (NO), hydrogen sulfide (H₂S), and phenylpropane metabolism in fruits during storage. “Xintaihong” peach were treated with 0.5, 1.0, 1.5 mmol L⁻¹ GSNO in 0.5% (w/v) β-CD solution (GSNO/β-CD). The effects of GSNO/β-CD on endogenous NO, H₂S, and phenylpropane metabolism were investigated. Treatment with GSNO/β-CD increased the color difference of peach and inhibited the increase of respiratory intensity, weight loss, and relative conductivity. Treatment with 1.0 mmol L⁻¹ GSNO/β-CD increased the nitric oxide synthase (NOS-like) activity and L-arginine content, thereby promoting the accumulation of endogenous NO. By improving the activities of L-cysteine desulfhydrylase (L-CD), O-acetylserine sulfur lyase (OAS-TL), serine acetyltransferase (SAT), GSNO/β-CD increased the content of endogenous H₂S in peach. Treatment with GSNO/β-CD increased the activities of phenylalanine ammonia-lyase (PAL), 4-coumarate-CoA ligase (4CL), and cinnamic acid-4-hydroxylase (C4H), promoted the increase of total phenols, flavonoids, and lignin in peach. These results indicated that GSNO/β-CD treatment better maintained the quality of peach by improving the metabolism of endogenous NO, H₂S, and phenylpropane during storage.     

Comparative Transcriptome Analyses Reveal Genes Related to Spine Development in Cucumber (<i>Cucumis sativus</i>)

Fruit spine is an important quality trait of cucumber. To better understand the molecular basis of cucumber spine development and function, RNA-Seq was performed to identify differentially expressed genes (DEGs) in fruit spines of different development stages, namely, 8 days before anthesis (SpBA8), anthesis (SpA) and 8 days after anthesis (SpAA8). Stage-wise comparisons obtained 2,259 (SpBA8 vs. SpA), 4,551 (SpA vs. SpAA8), and 5,290 (SpBA8 vs. SpAA8) DEGs. All the DEGs were classified into eight expression clusters by trend analysis. Among these DEGs, in addition to the Mict, Tril, CsTTG1, CsMYB6, NS, and Tu genes that have been reported to regulate fruit spine formation, we found that the CsHDG11, CsSCL8, CsSPL8, CsZFP6 and CsZFP8 may also be involved in spine development in cucumber. Our study provides a theoretical basis for further research on molecular mechanisms of spine development in cucumber.     

Investigation of <i>GhFAT</i> Genes Related to Seed Oil Content and Fatty Acid Composition in <i>Gossypium hirsutum</i> L.

Fatty Acyl-ACP thioesterase (FAT) is a key enzyme controlling oil biosynthesis in plant seeds. FATs can be divided into two subfamilies, FATA and FATB according to their amino acid sequences and substrate specificity. The Upland cotton genome contains 20 GhFAT genes, amongst which 6 genes were of the GhFATA subfamily and 14 of the GhFATB subfamily. The 20 GhFAT genes are unevenly distributed on 14 chromosomes. The GhFATA genes have 5 or 7 exons and the GhFATB genes have 6 or 7 exons. All GhFAT proteins have the conserved Acyl-ACP_TE domain and PLN02370 super family, the typical characteristics of plant thioesterases. Analyses of the expression level of GhFATs and the compositions of fatty acid in 5–60 days-post-anthesis seeds showed that the ratio of saturated fatty acids to unsaturated fatty acids was consistent with the expression profile of GhFATB12, GhFATB3, and GhFATB10; the ratio of monounsaturated fatty acid to polyunsaturated fatty acids was consistent with the expression profile of GhFATA3. The oil contents of mature cottonseeds were positively correlated with the contents of palmitic acid and linolenic acid as well as seed vigor. These results provide essential information for further exploring the role(s) of the specific GhFATs in determining oil biosynthesis and cottonseed compositions.     

Melatonin Promotes Rice Seed Germination under Drought Stress by Regulating Antioxidant Capacity

Drought stress is a serious threat to the germination of plant seeds and the growth of seedlings. Melatonin has been proven to play an important role in alleviating plant stress. However, its effect on seed germination under drought conditions is still poorly understood. Therefore, we studied the effects of melatonin on rice seed germination and physiological characteristics under drought stress. Rice seeds were treated with different concentrations of melatonin (i.e., 0, 20, 100, and 500 μM) and drought stress was simulated with 5% polyethylene glycol 6000 (PEG6000). The results showed that 100 μM melatonin can effectively improve the germination potential, rate and index; the vigor index of rice seeds; and the length of the shoot and root. In addition, that treatment also increased the activity of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT), and reduced the content of malondialdehyde (MDA). The grey relational grade between the shoot MDA content and the melatonin seed-soaking treatment was the highest, which could be useful for evaluating the effect of melatonin on drought tolerance. Two-way analysis of variance showed that the effect of single melatonin treatment on rice seeds was more significant than that of single drought stress and interaction treatment of drought and melatonin (p < 0.05). The subordinate function results showed that 100 μM melatonin significantly improved the germination and physiological indexes of rice seeds and effectively alleviated the adverse effects of drought stress on rice seedlings. The results helped to improve the understanding of the morphological and physiological involvement of melatonin in promoting seed germination and seedling development under drought stress.