Mutation of the iron ligand His 249 to Glu in the N-lobe of human transferrin abolishes the dilysine "trigger" but does not significantly affect iron release

Serum transferrin is the major iron transport protein in humans. Its function depends on its ability to bind iron with very high affinity, yet to release this bound iron at the lower intracellular pH. Possible explanations for the release of iron from transferrin at low pH include protonation of a histidine ligand and the existence of a pH-sensitive "trigger" involving a hydrogen-bonded pair of lysines in the N-lobe of transferrin. We have determined the crystal structure of the His249Glu mutant of the N-lobe half-molecule of human transferrin and compared its iron-binding properties with those of the wild-type protein and other mutants. The crystal structure, determined at 2.4 A resolution (R-factor 19.8%, R(free) 29.4%), shows that Glu 249 is directly bound to iron, in place of the His ligand, and that a local movement of Lys 296 has broken the dilysine interaction. Despite the loss of this potentially pH-sensitive interaction, the H249E mutant is only slightly more acid-stable than wild-type and releases iron slightly faster. We conclude that the loss of the dilysine interaction does make the protein more acid stable but that this is counterbalanced by the replacement of a neutral ligand (His) by a negatively charged one (Glu), thus disrupting the electroneutrality of the binding site.     

Unique Microstructural Changes in the Brain Associated with Urological Chronic Pelvic Pain Syndrome (UCPPS) Revealed by Diffusion Tensor MRI,Super-Resolution Track Density Imaging,and Statistical Parameter Mapping: A MAPP Network Neuroimaging Study

Studies have suggested chronic pain syndromes are associated with neural reorganization in specific regions associated with perception, processing, and integration of pain. Urological chronic pelvic pain syndrome (UCPPS) represents a collection of pain syndromes characterized by pelvic pain, namely Chronic Prostatitis/Chronic Pelvic Pain Syndrome (CP/CPPS) and Interstitial Cystitis/Painful Bladder Syndrome (IC/PBS), that are both poorly understood in their pathophysiology, and treated ineffectively. We hypothesized patients with UCPPS may have microstructural differences in the brain compared with healthy control subjects (HCs), as well as patients with irritable bowel syndrome (IBS), a common gastrointestinal pain disorder. In the current study we performed population-based voxel-wise DTI and super-resolution track density imaging (TDI) in a large, two-center sample of phenotyped patients from the multicenter cohort with UCPPS (N = 45), IBS (N = 39), and HCs (N = 56) as part of the MAPP Research Network. Compared with HCs, UCPPS patients had lower fractional anisotropy (FA), lower generalized anisotropy (GA), lower track density, and higher mean diffusivity (MD) in brain regions commonly associated with perception and integration of pain information. Results also showed significant differences in specific anatomical regions in UCPPS patients when compared with IBS patients, consistent with microstructural alterations specific to UCPPS. While IBS patients showed clear sex related differences in FA, MD, GA, and track density consistent with previous reports, few such differences were observed in UCPPS patients. Heat maps illustrating the correlation between specific regions of interest and various pain and urinary symptom scores showed clustering of significant associations along the cortico-basal ganglia-thalamic-cortical loop associated with pain integration, modulation, and perception. Together, results suggest patients with UCPPS have extensive microstructural differences within the brain, many specific to syndrome UCPPS versus IBS, that appear to be localized to regions associated with perception and integration of sensory information and pain modulation, and seem to be a consequence of longstanding pain.     

肠内营养对乳腺癌术后化疗患者肠道菌群及生活质量的影响

目的研究肠内营养对乳腺癌术后化疗患者肠道菌群、生活质量、营养指标水平的影响。方法选取2012年7月至2018年1月于我院进行乳腺癌术后化疗的91例女性乳腺癌患者为研究对象,根据是否进行肠内营养将患者分为肠内营养组和对照组,观察化疗前后2组患者肠道菌群、生活质量、营养指标水平的变化及不良反应发生情况。结果治疗前2组患者肠道菌群、生活质量、营养指标水平差异无统计学意义(均P0.05)。治疗后,肠内营养组患者肠道双歧杆菌数量为(6.7±0.5)lg CFU/g、乳杆菌数量为(8.5±0.4)lg CFU/g,均显著高于治疗前,同时显著高于对照组(均P0.05)。治疗后肠内营养组患者出现反酸、腹胀、便秘等胃肠道不良反应的比例与对照组比较差异无统计学意义(均P0.05)。治疗后两组患者总体健康、认知功能、情绪功能、角色功能、社会功能、活力、躯体疼痛、躯体功能评分显著高于治疗前(均P0.05),且肠内营养组患者生活质量各指标的评分显著高于对照组(均P0.05)。治疗后肠内营养组患者血清总蛋白(TB)、血清清蛋白(ALB)、血清前清蛋白(PA)、转铁蛋白(TF)水平均显著高于对照组(均P0.05)。结论肠内营养可预防乳腺癌术后化疗患者肠道菌群的紊乱及营养不良的发生,安全有效,有助于提高乳腺癌患者的生活质量。     

Hybridization between diploid Centaurea pseudophrygia and tetraploid C. jacea (Asteraceae): the role of mixed pollination,unreduced gametes,and mentor effects

We studied hybridization between the diploid Centaurea pseudophrygia and the tetraploid C. jacea by performing crossing experiments and screening natural populations using flow cytometry. The experiments confirm that the studied species exhibit strong reproductive isolation. Interspecific hybrids were formed at a low frequency, including triploids (originating from reduced gametes) and tetraploids (involving unreduced gametes of the diploids). In contrast, hybrids were almost absent among seeds and adult plants of natural mixed populations and among the offspring from experimental pollinations with a mixture of pollen of both ploidy levels. We found that mixed pollination is an important mechanism for preventing hybridization between plants of different ploidy levels and sustaining the reproduction of the tetraploids. A mentor effect (induced selfing in the presence of pollen of different ploidy levels) was observed in both diploids and tetraploids, reinforcing the reproductive isolation between cytotypes. Higher ploidy levels (pentaploid, hexaploid) involving unreduced gametes of the tetraploid species were identified. Notably, pentaploids were discovered for the first time in Centaurea sect. Jacea. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 104 , 93–106.     

马卵母细胞体外成熟的初步研究

采用抽吸法和切割法两种采卵方法收集马卵母细胞,显示采用切割法的卵母细胞回收率为83%,高于抽吸法的回收率46.5%(P＜0.05),在卵母细胞的成熟上,使用M199和DMEM/F12两种培养液为基础液的成熟体系,紧凑型(Cp)COCs和扩展型(Ex)COCs在以M199为基础液和以DMEM/F12为基础液的培养液中的卵母细胞成熟率分别为41.7%和64.7%、46.7%和66.7%,差异不显著(P＞0.05).两种培养体系中成熟的Cp COCs采用Ionomycin与6-DMAP和CHX联合激活,在以M199和以DMEM/F12为基础液的培养液中成熟的卵母细胞的卵裂率分别为45%和57.1%,差异不明显(P＞0.05).     

Murine nasal septa for respiratory epithelial air-liquid interface cultures

Air-liquid interface models using murine tracheal respiratory epithelium have revolutionized the in vitro study of pulmonary diseases. This model is often impractical because of the small number of respiratory epithelial cells that can be isolated from the mouse trachea. We describe a simple technique to harvest the murine nasal septum and grow the epithelial cells in an air-liquid interface. The degree of ciliation of mouse trachea, nasal septum, and their respective cultured epithelium at an air-liquid interface were compared by scanning electron microscopy (SEM). Immunocytochemistry for type IV beta-tubulin and zona occludens-1 (Zo-1) are performed to determine differentiation and confluence, respectively. To rule out contamination with olfactory epithelium (OE), immunocytochemistry for olfactory marker protein (OMP) was performed. Transepithelial resistance and potential measurements were determined using a modified vertical Ussing chamber SEM reveals approximately 90% ciliated respiratory epithelium in the nasal septum as compared with 35% in the mouse trachea. The septal air-liquid interface culture demonstrates comparable ciliated respiratory epithelium to the nasal septum. Immunocytochemistry demonstrates an intact monolayer and diffuse differentiated ciliated epithelium. These cultures exhibit a transepithelial resistance and potential confirming a confluent monolayer with electrically active airway epitheliumn containing both a sodium-absorptive pathway and a chloride-secretory pathway. To increase the yield of respiratory epithelial cells harvested from mice, we have found the nasal septum is a superior source when compared with the trachea. The nasal septum increases the yield of respiratory epithelial cells up to 8-fold.     

Melanothamnus maniticola sp. nov. (Ceramiales,Rhodophyta): an epizoic species evolved for living on the West Indian Manatee

Over 35 macroalgae have been documented growing epizoically on sea turtles, and macroalgae are also known to grow on the West Indian Manatee, but the number and identity of these latter species have not been determined. Analysis of DNA sequences of 12 samples collected from different manatees captured in three areas of Florida indicated that they represented a single undescribed species within the Rhodomelaceae genus Melanothamnus. Morphological analysis revealed Melanothamnus characteristics but also a previously undescribed combination of character states. These include eight to nine, but as many as 11, pericentral cells; heavy cortication restricted to the base of thalli, and a sharp transition between the corticated and ecorticate sections of the thallus; cells surrounding the ostiole being similar in size to the outer pericarp cells immediately below, and robust rhizoids that have no terminal lobes and develop from central axial cell filaments instead of pericentral cells. The unique characteristics of the rhizoids may be evolutionary adaptations for anchoring the thalli to manatee epidermis. This species is described as M. maniticola sp. nov.     

Physical Labeling of Papillomavirus-Infected, Immortal, and Cancerous Cervical Epithelial Cells Reveal Surface Changes at Immortal Stage

A significant change of surface features of malignant cervical epithelial cells compared to normal cells has been previously reported. Here, we are studying the question at which progressive stage leading to cervical cancer the surface alteration happens. A non-traditional method to identify malignant cervical epithelial cells in vitro, which is based on physical (in contrast to specific biochemical) labelling of cells with fluorescent silica micron-size beads, is used here to examine cells at progressive stages leading to cervical cancer which include normal epithelial cells, cells infected with human papillomavirus type-16 (HPV-16), cells immortalized by HPV-16, and carcinoma cells. The study shows a statistically significant (at p < 0.01) difference between both immortal and cancer cells and a group consisting of normal and infected. There is no significant difference between normal and infected cells. Immortal cells demonstrate the signal which is closer to cancer cells than to either normal or infected cells. This implies that the cell surface, surface cellular brush changes substantially when cells become immortal. Physical labeling of the cell surface represents a substantial departure from the traditional biochemical labeling methods. The results presented show the potential significance of physical properties of the cell surface for development of clinical methods for early detection of cervical cancer, even at the stage of immortalized, premalignant cells.