厌氧发酵液中溶解性有机物对活性污泥合成聚羟基脂肪酸酯影响的研究进展

利用活性污泥微生物将剩余污泥发酵液中的挥发性脂肪酸(Volatile fatty acids,VFAs)转化为聚羟基脂肪酸酯(Polyhydroxyalkanoates,PHA)是目前环境生物技术领域的研究热点。但针对发酵液中非VFAs物质(主要是溶解性有机物,Dissolved organic matter,DOM)对活性污泥合成PHA的影响目前仍未有统一的结论,需要进行较全面的分析和总结。因此,文中首先介绍了剩余污泥发酵液中DOM的主要特性及常见分析方法,然后从微生物学、代谢调控、污泥性质等角度分析了DOM中几种主要组分(多聚糖、蛋白类物质、腐殖质)对活性污泥合成PHA的影响。综合各研究结果表明高浓度DOM不利于PHA的生产,但适量DOM的存在有利于污泥性质的稳定,同时能降低PHA提纯成本。最后提出了相应的策略来实现对活性污泥利用DOM合成PHA的调控,以期为高效利用厌氧发酵液中DOM实现PHA合成提供解决思路。     

Crumbs proteins stabilize the cone mosaics of photoreceptors and improve vision in zebrafish

Although the unique organization of vertebrate cone mosaics was first described long ago,both their underlying molecular basis and physiological significance are largely unknown.Here,we demonstrate that Crumbs proteins,the key regulators of epithelial apical polarity,establish the planar cellular polarity of photoreceptors in zebrafish.Via heterophilic Crb2a-Crb2b interactions,the apicobasal polarity protein Crb2b restricts the asymmetric planar distribution of Crb2a in photoreceptors.The planar polarized Crumbs proteins thus balance intercellular adhesions and tension between photoreceptors,thereby stabilizing the geometric organization of cone mosaics.Notably,loss of Crb2b in zebrafish induces a nearsightedness-like phenotype in zebrafish accompanied by an elongated eye axis and impairs zebrafish visual perception for predation.These data reveal a detailed mechanism for cone mosaic homeostasis via previously undiscovered apical-planar polarity coordination and propose a pathogenic mechanism for nearsightedness.     

Re-detectable positive SARS-CoV-2 RNA tests in patients who recovered from COVID-19 with intestinal infection

Dear Editor,Severe acute respiratory syndrome coronavirus 2(SARSCoV-2),a novel coronavirus that causes Coronavirus Disease 2019(COVID-19)(Yang and Wang,2020),has spread to more than 200 countries and infected more than 9,000,000 people as of Jun 2020.Tens of thousands of patients with COVID-19 have recovered and been discharged from hospital.However,there are reports of recovered patients who subsequently tested positive for SARSCoV-2 after discharge(re-detectable positive,RP)(An et al.,2020;Lan et al.,2020),and this has led to increasing focus on the mechanism(s)underlying RP.     

CX3CL1 promotes tumour cell by inducing tyrosine phosphorylation of cortactin in lung cancer

It has been reported that chemokine CX₃CL1 can regulate various tumours by binding to its unique receptor CX₃CR1. However, the effect of CX₃CL1-CX₃CR1 on the lung adenocarcinoma and lung squamous cell carcinoma is still unclear. Here, we showed that CX₃CL1 can further invasion and migration of lung adenocarcinoma A549 and lung squamous cell carcinoma H520. In addition, Western blot and immunofluorescence test indicated CX₃CL1 up-regulated the phosphorylation level of cortactin, which is a marker of cell pseudopodium. Meanwhile, the phosphorylation levels of c-Src and c-Abl, which are closely related to the regulation of cortactin phosphorylation, are elevated. Nevertheless, the src/abl inhibitor bosutinib and mutations of cortactin phosphorylation site could inhibit the promotion effect of CX₃CL1 on invasion and migration of A549 and H520. Moreover, these results of MTT, Hoechst staining and Western blot suggested that CX₃CL1 had no effect on the proliferation and apoptosis of A549 and H520 in vitro. The effects of CX₃CL1 were also verified by the subcutaneous tumour formation in nude mice, which showed that it could promote proliferation and invasion of A549 in vivo. In summary, our results indicated that CX₃CL1 furthered invasion and migration in lung cancer cells partly via activating cortactin, and CX₃CL1 may be a potential molecule in regulating the migration and invasion of lung cancer.     

Bone morphogenetic protein 9 overexpression reduces osteosarcoma cell migration and invasion

Transforming growth factor-β (TGF-β) is known to promote tumor migration and invasion. Bone morphogenetic proteins (BMPs) are members of the TGF-β family expressed in a variety of human carcinoma cell lines. The role of bone morphogenetic protein 9 (BMP9), the most powerful osteogenic factor, in osteosarcoma (OS) progression has not been fully clarified. The expression of BMP9 and its receptors in OS cell lines was analyzed by RT-PCR. We found that BMP9 and its receptors were expressed in OS cell lines. We further investigated the influence of BMP9 on the biological behaviors of OS cells. BMP9 overexpression in the OS cell lines 143B and MG63 inhibited in vitro cell migration and invasion. We further investigated the expression of a panel of cancer-related genes and found that BMP9 overexpression increased the phosphorylation of Smad1/5/8 proteins, increased the expression of ID1, and reduced the expression and activity of matrix metalloproteinase 9 (MMP9) in OS cells. BMP9 silencing induced the opposite effects. We also found that BMP9 may not affect the chemokine (C-X-C motif) ligand 12 (CXCL12)/C-X-C chemokine receptor type 4 (CXCR4) axis to regulate the invasiveness and metastatic capacity of OS cells. Interestingly, CXCR4 was expressed in both 143B and MG63 cells, while CXCL12 was only detected in MG63 cells. Taken together, we hypothesize that BMP9 inhibits the migration and invasiveness of OS cells through a Smad-dependent pathway by downregulating the expression and activity of MMP9.     

Impact of the Economic Recession on Companion Animal Relinquishment,Adoption, and Euthanasia: A Chicago Animal Shelter's Experience

This study investigated how the current economic recession (since December 2007) has affected dog and cat relinquishment, adoption, and euthanasia at the Anti-Cruelty Society animal shelter in Chicago, Illinois. The study compared temporal patterns of the investigated statistics before (2000–2007) the start of the current recession with the patterns after the start of the recession (2008–2010). The results showed that once the guardianship (ownership) of a nonhuman animal had been established, the recession did not greatly affect the owner's decision on relinquishment—except for the relinquishment of senior dogs, which may be associated with increased costs of care. However, an unfavorable economic environment may have reduced adoption of animals. The consequences of a decline in adoptions might be reflected in an increase in the proportion or number of sheltered animals euthanized. This study demonstrated how monitoring changes in temporal patterns in these shelter statistics can help guide animal shelters to better prepare for the current recession.     

Oxidative DNA and RNA damage and their prognostic values during Salmonella enteritidis-induced intestinal infection in rats

Abstract

Emerging evidence suggests that microbial pathogens may induce oxidative stress in infected hosts. The aim of the present study was to investigate the relationship between changes in oxidative stress and intestinal infection with and without antibiotic treatment in animal models. Sprague-Dawley (SD) rats were divided into three groups: rats infected with Salmonella enterica serovar Enteritidis (S. enteritidis), rats infected with S. enteritidis followed by norfloxacin treatment, and the control group. To evaluate oxidative stress changes, levels of 8-oxo-7,8-dihydroguanosine (8-oxo-Gsn) and 8-oxo-7,8-dihydro-2-deoxyguanosine (8-oxo-dGsn), which represented oxidative damage to RNA and DNA, respectively, were analysed in urine and tissue samples. In urine, the level of 8-oxo-Gsn increased significantly after oral exposure to S. enteritidis (p?≤?0.001) and returned to baseline after recovery. Notably, norfloxacin treatment decreased the level of 8-oxo-Gsn in urine significantly (p?=?0.001). Changes of 8-oxo-Gsn measured in tissues from the small intestine, colon, liver and spleen were consistent with 8-oxo-Gsn measured in urine. Our study suggested that 8-oxo-Gsn in urine may serve as a highly sensitive biomarker for evaluating the severity of S. enteritidis infection and the effectiveness of antibiotic treatment against infection.     

Unique Characteristics of Pb in Soil Contaminated by Red Lead Anti-Corrosion Paint

Red lead (Pb₃O₄) has been extensively used in the past in anti-corrosion paints for the protection of steel constructions such as electricity pylons or bridges. Until recently, little has been known about the behavior of these Pb compounds in soils. Therefore, three pylon soils and six red lead anti-corrosion paints were characterized in terms of solubility, Pb mineral composition, extractability, sorption and desorption, and the chemical speciation of Pb in soil extracts. The pylon soils were characterized by moderate total Pb concentrations (≈700 mg kg^?1), while NH₄NO₃ extractable Pb was exceptionally high (up to 15% of total Pb). In soil extracts, the free Pb²⁺ fraction ranged from 33 to 81% of total soluble Pb. The equilibrium concentration of Pb derived from Pb₃O₄ in ultra-pure water reached 68.5 mg L^?1. This high solubility explains the observed high extractability in soils and contradicts earlier reports of much lower water solubilities of the compound.     

Heat shock protein 27 is increased in cyanotic tetralogy of Fallot myocardium and is associated with improved cardiac output and contraction

Tetralogy of Fallot (TOF) is a congenital heart condition in which the right ventricle is exposed to cyanosis and pressure overload. Patients have an increased risk of right ventricle dysfunction following corrective surgery. Whether the cyanotic myocardium is less tolerant of injury compared to non-cyanotic is unclear. Heat shock proteins (HSPs) protect against cellular stresses. The aim of this study was to examine HSP 27 expression in the right ventricle resected from TOF patients and determine its relationship with right ventricle function and clinical outcome. Ten cyanotic and ten non-cyanotic patients were studied. Western blotting was used to quantify HSP 27 in resected myocardium at (1) baseline (first 15 min of aortic cross clamp and closest representation of pre-operative status) and (2) after 15 min during ischemia until surgery was complete. The cyanotic group had significantly increased haematocrit, lower O₂ saturation, thicker interventricular septal wall thickness and released more troponin-I on post-operative day 1 (p?<?0.05). HSP 27 expression was significantly increased in the <15 min cyanotic compared to the <15 min non-cyanotic group (p?=?0.03). In the cyanotic group, baseline HSP 27 expression also significantly correlated with oxygen extraction ratio (p?=?0.028), post-operative basal septal velocity (p?=?0.036) and mixed venous oxygen saturation (p?=?0.02), markers of improved cardiac output/contraction. Increased HSP 27 expression and associated improved right ventricle function and systemic perfusion supports a cardio-protective effect of HSP 27 in cyanotic TOF.