IgE-Binding Epitope Mapping and Tissue Localization of the Major American Cockroach Allergen Per a 2

Purpose

Cockroaches are the second leading allergen in Taiwan. Sensitization to Per a 2, the major American cockroach allergen, correlates with clinical severity among patients with airway allergy, but there is limited information on IgE epitopes and tissue localization of Per a 2. This study aimed to identify Per a 2 linear IgE-binding epitopes and its distribution in the body of a cockroach.

Methods

The cDNA of Per a 2 was used as a template and combined with oligonucleotide primers specific to the target areas with appropriate restriction enzyme sites. Eleven overlapping fragments of Per a 2 covering the whole allergen molecule, except 20 residues of signal peptide, were generated by PCR. Mature Per a 2 and overlapping deletion mutants were affinity-purified and assayed for IgE reactivity by immunoblotting. Three synthetic peptides comprising the B cell epitopes were evaluated by direct binding ELISA. Rabbit anti-Per a 2 antibody was used for immunohistochemistry.

Results

Human linear IgE-binding epitopes of Per a 2 were located at the amino acid sequences 57-86, 200-211, and 299-309. There was positive IgE binding to 10 tested Per a 2-allergic sera in 3 synthetic peptides, but none in the controls. Immunostaining revealed that Per a 2 was localized partly in the mouth and midgut of the cockroach, with the most intense staining observed in the hindgut, suggesting that the Per a 2 allergen might be excreted through the feces.

Conclusions

Information on the IgE-binding epitope of Per a 2 may be used for designing more specific diagnostic and therapeutic approaches to cockroach allergy.     

垂盆草苷对幼龄肝内胆汁淤积大鼠的作用机制

研究垂盆草苷(sarmentosin,SA)对幼龄肝内胆汁淤积大鼠的干预和调节作用。将48只SD幼龄大鼠随机分为正常组(Control)、α-萘异硫氰酸酯(ANIT)组(Model)、熊去氧胆酸(UDCA)阳性对照组、垂盆草苷低、中、高剂量组,每组8只,除正常组外,各组大鼠连续1周分别灌胃给予相应药物,每日1次。在第5 d灌胃给予80 mg/kg ANIT造模。在造模后48 h测定大鼠的胆汁流量;测定大鼠血清中丙氨酸转氨酶(ALT)、天冬氨酸转氨酶(AST)、碱性磷酸酶(ALP)的活性和总胆红素(TBIL)、直接胆红素(DBIL)、总胆汁酸(TBA)的含量;检测肝脏组织病理变化和组织匀浆中丙二醛(MDA)、超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)的含量;测定血清中肿瘤坏死因子(TNF-α)、γ-干扰素(INF-γ)、白细胞介素1β(IL-1β)的表达;Western blot法分析胆汁酸转运蛋白与合成蛋白。与正常组相比,模型组胆汁流量受到明显的抑制;大鼠肝组织出现明显的病理损伤;血清中ALT、AST、ALP、TBIL、DBIL、TBA水平显著升高;组织匀浆中MDA含量显著升高,SOD和GSH-Px含量显著降低;炎症因子TNF-α、IFN-γ、IL-1β的表达升高(P<0.05,P<0.01);FXR、SHP-1、SHP-2、MREP2、BSEP、NTCP蛋白表达下降,CYP7A1、CYP27A1蛋白表达升高。与模型组相比,垂盆草苷各剂量组大鼠的胆汁流量呈现不同程度的增加;大鼠肝脏组织的病理损伤有所改善;血清中ALT、AST、ALP、TBIL、DBIL、TBA水平降低;肝脏组织匀浆中MDA的含量降低,SOD、GSH-Px的含量升高(P<0.05,P<0.01);TNF-α、IFN-γ、IL-1β的表达降低(P<0.05,P<0.01);结果表明垂盆草苷对于胆汁淤积有一定的治疗效果,其中垂盆草苷高剂量的作用效果与UDCA组相当,同时垂盆草苷可上调FXR、SHP-1、SHP-2、MREP2、BSEP、NTCP蛋白表达,下调CYP7A1、CYP27A1蛋白表达,说明垂盆草苷通过调控相关蛋白发挥作用。垂盆草苷对ANIT所致的SD幼龄大鼠肝内胆汁淤积有明显的干预和调节作用。可能是通过参与胆汁酸的转运与合成发挥其治疗作用。     

Syntrophic exchange in synthetic microbial communities

Metabolic crossfeeding is an important process that can broadly shape microbial communities. However, little is known about specific crossfeeding principles that drive the formation and maintenance of individuals within a mixed population. Here, we devised a series of synthetic syntrophic communities to probe the complex interactions underlying metabolic exchange of amino acids. We experimentally analyzed multimember, multidimensional communities of Escherichia coli of increasing sophistication to assess the outcomes of synergistic crossfeeding. We find that biosynthetically costly amino acids including methionine, lysine, isoleucine, arginine, and aromatics, tend to promote stronger cooperative interactions than amino acids that are cheaper to produce. Furthermore, cells that share common intermediates along branching pathways yielded more synergistic growth, but exhibited many instances of both positive and negative epistasis when these interactions scaled to higher dimensions. In more complex communities, we find certain members exhibiting keystone species-like behavior that drastically impact the community dynamics. Based on comparative genomic analysis of >6,000 sequenced bacteria from diverse environments, we present evidence suggesting that amino acid biosynthesis has been broadly optimized to reduce individual metabolic burden in favor of enhanced crossfeeding to support synergistic growth across the biosphere. These results improve our basic understanding of microbial syntrophy while also highlighting the utility and limitations of current modeling approaches to describe the dynamic complexities underlying microbial ecosystems. This work sets the foundation for future endeavors to resolve key questions in microbial ecology and evolution, and presents a platform to develop better and more robust engineered synthetic communities for industrial biotechnology.Microbes are abundantly found in almost every part of the world, living in communities that are diverse in many facets. Although it is clear that cooperation and competition within microbial communities is central to their stability, maintenance, and longevity, there is limited knowledge about the general principles guiding the formation of these intricate systems. Understanding the underlying governing principles that shape a microbial community is key for microbial ecology but is also crucial for engineering synthetic microbiomes for various biotechnological applications (1–3). Numerous such examples have been recently described including the bioconversion of unprocessed cellulolytic feedstocks into biofuel isobutanol using fungal–bacterial communities (4) and biofuel precursor methyl halides using yeast–bacterial cocultures (5). Other emerging applications in biosensing and bioremediation against environmental toxins such as arsenic (6) and pathogens such as Pseudomonas aeruginosa and Vibrio cholerae have been demonstrated using engineered quorum-sensing Escherichia coli (7, 8). These advances paint an exciting future for the development of sophisticated multispecies microbial communities to address pressing challenges and the crucial need to understand the basic principles that enables their design and engineering.An important process that governs the growth and composition of microbial ecosystems is the exchange of essential metabolites, known as metabolic crossfeeding. Entomological studies have elucidated on a case-by-case basis the importance of amino acids in natural interkingdom and interspecies exchange networks (9–11). Recent comparative analyses of microbial genomes suggest that a significant proportion of all bacteria lack essential pathways for amino acid biosynthesis (2). These auxotrophic microbes thus require extracellular sources of amino acids for survival. Understanding amino acid exchange therefore presents an opportunity to gain new insights into basic principles in metabolic crossfeeding. Recently, several studies have used model systems of Saccharomyces cerevisiae (12), Saccharomyces enterica (13), and E. coli (14–16) to study syntrophic growth of amino acid auxotrophs in coculture environments. Numerous quantitative models have also been developed to describe the behavior of these multispecies systems, including those that integrate dynamics (17, 18), metabolism (19–21), and spatial coordination (22). Although these efforts have led to an improved understanding of the dynamics of syntrophic pairs and the energetic and benefits of cooperativity in these simple systems (23), larger more complex syntrophic systems have yet to be explored.Here, we use engineered E. coli mutants to study syntrophic crossfeeding, scaling to higher-dimensional synthetic ecosystems of increasing sophistication. We first devised pairwise syntrophic communities that show essential and interesting dynamics that can be predicted by simple kinetic models. We then increased the complexity of the interaction in three-member synthetic consortia involving crossfeeding of multiple metabolites. To further increase the complexity of our system, we devised a 14-member community to understand key drivers of population dynamics over short and evolutionary timescales. Finally, we provide evidence for widespread trends of metabolic crossfeeding based on comparative genomic analysis of amino acid biosynthesis across thousands of sequenced genomes. Our large-scale and systematic efforts represent an important foray into forward and reverse engineering synthetic microbial communities to gain key governing principles of microbial ecology and systems microbiology.     

Synthetic spatially graded Rac activation drives cell polarization and movement

Migrating cells possess intracellular gradients of active Rho GTPases, which serve as central hubs in transducing signals from extracellular receptors to cytoskeletal and adhesive machinery. However, it is unknown whether shallow exogenously induced intracellular gradients of Rho GTPases are sufficient to drive cell polarity and motility. Here, we use microfluidic control to generate gradients of a small molecule and thereby directly induce linear gradients of active, endogenous Rac without activation of chemotactic receptors. Gradients as low as 15% were sufficient not only to trigger cell migration up the chemical gradient but to induce both cell polarization and repolarization. Cellular response times were inversely proportional to the steepness of Rac inducer gradient in agreement with a mathematical model, suggesting a function for chemoattractant gradient amplification upstream of Rac. Increases in activated Rac levels beyond a well-defined threshold augmented polarization and decreased sensitivity to the imposed gradient. The threshold was governed by initial cell polarity and PI3K activity, supporting a role for both in defining responsiveness to Rac activation. Our results reveal that Rac can serve as a starting point in defining cell polarity. Furthermore, our methodology may serve as a template to investigate processes regulated by intracellular signaling gradients.     

Rewritable digital data storage in live cells via engineered control of recombination directionality

The use of synthetic biological systems in research, healthcare, and manufacturing often requires autonomous history-dependent behavior and therefore some form of engineered biological memory. For example, the study or reprogramming of aging, cancer, or development would benefit from genetically encoded counters capable of recording up to several hundred cell division or differentiation events. Although genetic material itself provides a natural data storage medium, tools that allow researchers to reliably and reversibly write information to DNA in vivo are lacking. Here, we demonstrate a rewriteable recombinase addressable data (RAD) module that reliably stores digital information within a chromosome. RAD modules use serine integrase and excisionase functions adapted from bacteriophage to invert and restore specific DNA sequences. Our core RAD memory element is capable of passive information storage in the absence of heterologous gene expression for over 100 cell divisions and can be switched repeatedly without performance degradation, as is required to support combinatorial data storage. We also demonstrate how programmed stochasticity in RAD system performance arising from bidirectional recombination can be achieved and tuned by varying the synthesis and degradation rates of recombinase proteins. The serine recombinase functions used here do not require cell-specific cofactors and should be useful in extending computing and control methods to the study and engineering of many biological systems.     

Controlled biosynthesis of odd-chain fuels and chemicals via engineered modular metabolic pathways

Microbial systems are being increasingly developed as production hosts for a wide variety of chemical compounds. Broader adoption of microbial synthesis is hampered by a limited number of high-yielding natural pathways for molecules with the desired physical properties, as well as the difficulty in functionally assembling complex biosynthetic pathways in heterologous hosts. Here, we address both of these challenges by reporting the adaptation of the butanol biosynthetic pathway for the synthesis of odd-chain molecules and the development of a complementary modular toolkit to facilitate pathway construction, characterization, and optimization in engineered Escherichia coli. The modular feature of our pathway enables multientry and multiexit biosynthesis of various odd-chain compounds at high efficiency. By varying combinations of the pathway and toolkit enzymes, we demonstrate controlled production of propionate, trans-2-pentenoate, valerate, and pentanol, compounds with applications that include biofuels, antibiotics, biopolymers, and aroma chemicals. Importantly, and in contrast to a previously used method to identify limitations in heterologous amorphadiene production, our bypass strategy was effective even without the presence of freely membrane-diffusible substrates. This approach should prove useful for optimization of other pathways that use CoA-derivatized intermediates, including fatty acid β-oxidation and the mevalonate pathway for isoprenoid synthesis.     

人工合成E-选择素对兔颈总动脉动脉瘤壁平滑肌细胞增殖活性的影响

目的 探讨人工合成E-选择素对兔颈总动脉动脉瘤壁平滑肌细胞增殖活性的影响.方法 新西兰白兔54只,雌雄各半,随机分成9组(每组6只),对照组;实验1、2、3、4周组;治疗l、2、3、4周组.用弹性蛋白酶(EA)滴注法建立兔右颈总动脉瘤模型,并用CTA和HE染色观察模型动脉瘤的形态学改变和病理变化,免疫组化分析基质金属蛋白酶-2(MMP-2)、细胞增殖核抗原(PCNA)和平滑肌α肌动蛋白(α-SMA)表达,Real-time PCR检测骨桥蛋白(OPN)和MMP-2 mRNA表达.结果 大体测量和CTA结果显示:治疗组与实验组相比,其动脉瘤高度和宽度均有不同程度减小;免疫组化结果显示:治疗组动脉瘤壁MMP-2蛋白表达与同期实验组相比均有减少,治疗1、2周组动脉瘤壁PCNA蛋白表达低于同期实验组,而治疗3、4周组动脉瘤壁PCNA蛋白表达与同期实验组比较表达升高;治疗组动脉瘤壁α-SMA蛋白表达低于同期实验组.Real-time PCR结果显示:治疗组动脉瘤壁OPN mRNA表达与同期实验组相比均有增加,而治疗组动脉瘤壁MMP-2 mRNA表达分别低于同期实验组.结论 人工合成E-选择素可以抑制兔颈总动脉瘤壁平滑肌细胞数目和层数的减少,有效促进兔颈总动脉瘤壁平滑肌细胞的增殖,使血管平滑肌细胞由收缩型向合成型转化,进而对动脉瘤壁起到一定的修复作用.     

The rise of new psychoactive substances and psychiatric implications: A wide-ranging,multifaceted challenge that needs far-reaching common legislative strategies

The ever-growing number of novel psychoactive substances (NPS) that have been surfacing globally, as well as related changes in drug abuse trends, undoubtedly constitute a difficult and multifaceted challenge for psychiatry. The intake and abuse of such substances has been linked to a risk of psychopathological disturbances, which stem from imbalances of a range of neurotransmitter pathways and receptors. Through an analysis of relevant research articles and reviews (particularly those outlining NPS neurological and cerebral mechanisms of action and psychopathological consequences arising from NPS abuse; research papers more closely focused on chemical/pharmacological aspects have been ruled out), through a systematic analysis of Pubmed, Medline, PsycLIT and EMBASE literature, as well as data released by health care institutions and drug enforcement agencies (among which the World Health Organization, the United Nations Office on Drugs and Crime, the European Monitoring Centre for Drugs and Drug Addiction, Eurojust, the Novel Psychoactive Treatment UK Network, the Court of Justice of the European Union), the authors aimed to elaborate on the most relevant data relative to NPS-related psychiatric effects, focusing on the conceptual and definition-related complexities inherent to NPS, clinical management and motivations for NPS use; moreover, an effort has been made to highlight the possible measures in order to tackle the unremitting rise of such elusive and potentially harmful substances.