黄芩甙对铜绿假单胞菌R质粒的消除作用

测定黄芩甙对铜绿假单胞菌R质粒的消除作用 ;以携带R质粒的铜绿假单胞菌株PA16为靶细菌 ,以黄芩甙作为R质粒消除剂 ,进行R质粒体内外消除试验 ;体外消除实验结果表明 ,黄芩甙对PA16的消除率为 5 .1% ,明显高于空白对照组 ,也高于EB对照组的结果 ;体内R质粒消除率为 12 .0 % ,明显高于对照组 ;黄芩甙在体内外对铜绿假单胞菌R质粒具有较强的消除作用 ,为其实际应用提供实验依据。     

Reduction in leaf size at higher altitudes across 39 broad-leaved herbaceous species on the northeastern Qinghai-Tibetan Plateau

青藏高原东北部39种阔叶草本植物叶大小随海拔增加而减少种间或种内的叶大小随环境变化存在很大的差异,但这些差异如何随海拔变化一直都在争论。我们在青藏高原东北缘的冷龙岭和达坂山,沿海拔3200–4400 m的山坡上选取生长在开阔环境下的39种阔叶草本植物,观测了叶大小、叶长、叶宽和比叶重。研究结果表明,随海拔增加叶片显著减小,而且叶片面积的减小主要受叶片长度的影响,即随海拔增加叶长度减小明显。此外,叶片面积与海拔之间的关系随物种、叶倾角和叶表面特征而不同。利用局地环境观测数据驱动的能量平衡模型分析发现：叶温能更密切地追随气温变化,叶大小变化对叶温的影响在高海拔更为强烈。同时,基于上述能量平衡的计算结果,我们认为青藏高原东北部阔叶草本植物的海拔分布上限大约为5400 m。     

Ungulate bocaparvovirus 4 and rodent bocavirus are different genotypes of the same species of virus

Bocaviruses are associated with many human infectious diseases, such as respiratory tract infections, gastroenteritis, and hepatitis. Rats are known to be reservoirs of bocaviruses, including rodent bocavirus and rat bocavirus. Recently, ungulate bocaparvovirus 4, a known porcine bocavirus, has also been found in rats. Thus, investigating bocaviruses in rats is important for determining the origin of the viruses and preventing and controlling their transmission. To the best of our knowledge, no study to date has investigated bocaviruses in the livers of rats. In this report, a total of 624 rats were trapped in southern China between 2014 and 2017. Liver and serum samples from rats were tested for the prevalence of bocaviruses using PCR. Sequences related to ungulate bocaparvovirus 4 and rodent bocavirus were detected in both liver and serum samples. Interestingly, the prevalence of ungulate bocaparvovirus 4 (reference strain:KJ622366.1) was higher than that of rodent bocavirus (reference strain:KY927868.1) in both liver (2.24% and 0.64%, respectively) and serum samples (2.19% and 0.44%, respectively). The NS1 regions of ungulate bocaparvovirus 4 and rodent bocavirus related sequences displayed over 84% and 88% identity at the nucleic acid and amino acid levels, respectively. Furthermore, these sequences had similar genomic structure, genomic features, and codon usage bias, and shared a common ancestor. These viruses also displayed greater adaptability to rats than pigs. Our results suggested that ungulate bocaparvovirus 4 and rodent bocavirus may originate from rats and may be different genotypes of the same bocavirus species.     

Mud-puddling in the yellow-spined bamboo locust, Ceracris kiangsu (Oedipodidae: Orthoptera): Does it detect and prefer salts or nitrogenous compounds from human urine?

C. kiangsu adults were observed visiting human urine, especially on hot summer days. The main chemicals in fresh human urine include inorganic salts and CO(NH₂)_2. When human urine was incubated, NH₄HCO₃ became the richest nitrogenous compound. The phagostimulants, repellents and attractants in urine were identified here. On the filter papers treated with fresh or incubated urine samples, the 5th instar nymphs and the adults started and continued gnawing around the edges, in contrast to the 3rd and the 4th instar nymphs. The consumed areas were dramatically greater on the filters treated with the urine samples incubated for 3-6 days. The feedings of both male and female adults were also stimulated by several urine-borne components such as NaCl, NaH₂PO₄, Na₂SO₄, KCl, NH₄Cl and NH₄HCO₃ but not by CO(NH₂)₂. Among them NaCl was the most powerful phagostimulant. The repelling, or attractive/arresting effects of CO(NH₂)₂ and NH₄HCO₃ were also evaluated by a two-choice test. When exposed to water- and CO(NH₂)₂ solution-immersed filters simultaneously, the adults prefer to stay on water-immersed filter. In contrast, when provided water- and NH₄HCO₃ solution-treated filters, the adults prefer to stay on NH₄HCO₃ solution-treated filter. This demonstrated that CO(NH₂)₂ acted as a repellent and NH₄HCO₃ as an attractant/arrestant. In the bamboo forest, similar feeding behavior was also elicited by NaCl, NH₄HCO₃ but not by CO(NH₂)₂. Comparing to NaCl solution, a mixed solution of NaCl and CO(NH₂)₂ (1:1) significantly decreased the consumed area of the treated filters whereas a mixed solution of NaCl and NH₄HCO₃ (1:1) dramatically increased the consumed area. These results demonstrated that the phagostimulatory effect by NaCl was reduced by CO(NH₂)₂ in fresh urine and was enhanced by NH₄HCO₃ in incubated urine.     

Leukocyte-epithelial interactions

As a 'double-edged sword', neutrophil (polymorphonuclear leukocyte) migration across epithelial-lined organs is an important component of host defense, but it also results in epithelial pathophysiology and disease symptoms. There have been significant advances in better understanding the mechanisms of how leukocytes cross the vascular endothelium to exit the bloodstream; however, many of the mechanisms that govern polymorphonuclear leukocyte transepithelial migration are different and we are only just beginning to understand them. Recent findings include new junctional adhesion molecules and carbohydrate moieties as receptors for migrating neutrophils. In addition, new insights into leukocyte-epithelial signaling events have emerged that are beginning to shed light on the role of SIRP-CD47 interactions in regulating the rate of neutrophil transepithelial migration and how neutrophils modulate epithelial barrier function.     

Cytoglobin Exhibits Anti-Fibrosis Activity on Liver In Vivo and In Vitro

Cytoglobin, generated using genetic engineering method, is a kind of recombinant human stellate cell activation-associated protein. We speculate that it could influence the development of hepatic fibrosis like Sellate cell activation-associated protein which was discovered by Kawada et al. Therefore, we investigated its anti-fibrosis effect on liver both in vivo and in vitro. During our research, we found that cytoglobin showed obvious effect compared with the control group on Thioacetamide-induced liver fibrosis in SD rats, including significantly decrease in aspartate aminotransferase, Hyaluronic acid, laminin and collagen I(Col I) levels in serum and hydroxyproline in livers, which are the important indices reflecting the degree of hepatic fibrosis. Meanwhile, the viability of rat hepatic stellate cell line T6 (HSC-T6) cells was inhibited by cytoglobin and the apoptosis induced by cytoglobin in HSC-T6 cells was detected by Annexin V/PI double staining. Activation of the caspase cascade including caspase-3 for the intrinsic pathways was demonstrated. The results also showed that the expression of Bcl-2 protein decreased whereas that of Bax protein increased, leading to an increase of the Bax/Bcl-2 ratio. Our results demonstrated that cytoglobin exhibited anti-fibrosis activity on livers in vivo and in vitro, involving apoptosis induction.     

论世界遗产地和生物圈保护区的关系

世界遗产地和生物圈保护区的概念都是在联合国教科文组织(UNESCO)主持下制定的,主要目的都在于保护世界的物种多样性和生态系统;彼此之间究竞有何异同,人们或许并不十分清楚,特别是许多生物圈保护区也包括在世界遗产名录中,这就常常造成某种混淆。实际上,两者具有不同的目的、目标、法律依据和管理原则,不应该有所混淆。本文就拟简略地探讨一下这个问题供有关方面参考。     

Ammonia-induced structural changes of the oxygen-evolving complex in photosystem II as revealed by light-induced FTIR difference spectroscopy

Light-induced Fourier transform infrared difference spectroscopy has been applied to studies of ammonia effects on the oxygen-evolving complex (OEC) of photosystem II (PSII). We found that NH(3) induced characteristic spectral changes in the region of the symmetric carboxylate stretching modes (1450-1300 cm(-1)) of the S(2)Q(A)(-)/S(1)Q(A) FTIR difference spectra of PSII. The S(2) state carboxylate mode at 1365 cm(-1) in the S(2)Q(A)(-)/S(1)Q(A) spectrum of the controlled samples was very likely upshifted to 1379 cm(-1) in that of NH(3)-treated samples; however, the frequency of the corresponding S(1) carboxylate mode at 1402 cm(-1) in the same spectrum was not significantly affected. These two carboxylate modes have been assigned to a Mn-ligating carboxylate whose coordination mode changes from bridging or chelating to unidentate ligation during the S(1) to S(2) transition [Noguchi, T., Ono, T., and Inoue, Y. (1995) Biochim. Biophys. Acta 1228, 189-200; Kimura, Y., and Ono, T.-A. (2001) Biochemistry 40, 14061-14068]. Therefore, our results show that NH(3) induced significant structural changes of the OEC in the S(2) state. In addition, our results also indicated that the NH(3)-induced spectral changes of the S(2)Q(A)(-)/S(1)Q(A) spectrum of PSII are dependent on the temperature of the FTIR measurement. Among the temperatures we measured, the strongest effect was seen at 250 K, a lesser effect was seen at 225 K, and little or no effect was seen at 200 K. Furthermore, our results also showed that the NH(3) effects on the S(2)Q(A)(-)/S(1)Q(A) spectrum of PSII are dependent on the concentrations of NH(4)Cl. The NH(3)-induced upshift of the 1365 cm(-1) mode is apparent at 5 mM NH(4)Cl and is completely saturated at 100 mM NH(4)Cl concentration. Finally, we found that CH(3)NH(2) has a small but clear effect on the spectral change of the S(2)Q(A)(-)/S(1)Q(A) FTIR difference spectrum of PSII. The effects of amines on the S(2)Q(A)(-)/S(1)Q(A) FTIR difference spectra (NH(3) > CH(3)NH(2) > AEPD and Tris) are inverse proportional to their size (Tris approximately AEPD > CH(3)NH(2) > NH(3)). Therefore, our results showed that the effects of amines on the S(2)Q(A)(-)/S(1)Q(A) spectrum of PSII are sterically selective for small amines. On the basis of the correlations between the conditions (dependences on the excitation temperature and NH(3) concentration and the steric requirement for the amine effects) that give rise to the NH(3)-induced upshift of the 1365 cm(-)(1) mode in the S(2)Q(A)(-)/S(1)Q(A) spectrum of PSII and the conditions that give rise to the altered S(2) state multiline EPR signal, we propose that the NH(3)-induced upshift of the 1365 cm(-1) mode is caused by the binding of NH(3) to the site on the Mn cluster that gives rise to the altered S(2) state multiline EPR signal. In addition, we found no significant NH(3)-induced change in the S(2)Q(A)(-)/S(1)Q(A) FTIR difference spectrum at 200 K. Under this condition, the OEC gives rise to the NH(3)-stabilized g = 4.1 EPR signal and a suppressed g = 2 multiline EPR signal. Our results suggest that the structural difference of the OEC between the normal g = 2 multiline form and the NH(3)-stabilized g = 4.1 form is small.     

Identification of Critical Regions in Human SAMHD1 Required for Nuclear Localization and Vpx-Mediated Degradation

The sterile alpha motif (SAM) and HD domain-containing protein-1 (SAMHD1) inhibits the infection of resting CD4+ T cells and myeloid cells by human and related simian immunodeficiency viruses (HIV and SIV). Vpx inactivates SAMHD1 by promoting its proteasome-dependent degradation through an interaction with CRL4 (DCAF1) E3 ubiquitin ligase and the C-terminal region of SAMHD1. However, the determinants in SAMHD1 that are required for Vpx-mediated degradation have not been well characterized. SAMHD1 contains a classical nuclear localization signal (NLS), and NLS point mutants are cytoplasmic and resistant to Vpx-mediated degradation. Here, we demonstrate that NLS-mutant SAMHD1 K11A can be rescued by wild-type SAMHD1, restoring its nuclear localization; consequently, SAMHD1 K11A became sensitive to Vpx-mediated degradation in the presence of wild-type SAMHD1. Surprisingly, deletion of N-terminal regions of SAMHD1, including the classical NLS, generated mutant SAMHD1 proteins that were again sensitive to Vpx-mediated degradation. Unlike SAMHD1 K11A, these deletion mutants could be detected in the nucleus. Interestingly, NLS-defective SAMHD1 could still bind to karyopherin-β1 and other nuclear proteins. We also determined that the linker region between the SAM and HD domain and the HD domain itself is important for Vpx-mediated degradation but not Vpx interaction. Thus, SAMHD1 contains an additional nuclear targeting mechanism in addition to the classical NLS. Our data indicate that multiple regions in SAMHD1 are critical for Vpx-mediated nuclear degradation and that association with Vpx is not sufficient for Vpx-mediated degradation of SAMHD1. Since the linker region and HD domain may be involved in SAMHD1 multimerization, our results suggest that SAMHD1 multimerization may be required for Vpx-mediation degradation.     

High-resolution crystal structure reveals a HEPN domain at the C-terminal region of S. cerevisiae RNA endonuclease Swt1

Swt1 is an RNA endonuclease that plays an important role in quality control of nuclear messenger ribonucleoprotein particles (mRNPs) in eukaryotes; however, its structural details remain to be elucidated. Here, we report the crystal structure of the C-terminal (CT) domain of Swt1 from Saccharomyces cerevisiae, which shares common characteristics of higher eukaryotes and prokaryotes nucleotide binding (HEPN) domain superfamily. To study in detail the full-length protein structure, we analyzed the low-resolution architecture of Swt1 in solution using small angle X-ray scattering (SAXS) method. Both the CT domain and middle domain exhibited a good fit upon superimposing onto the molecular envelope of Swt1. Our study provides the necessary structural information for detailed analysis of the functional role of Swt1, and its importance in the process of nuclear mRNP surveillance.