Hemolin expression in the silk glands of Galleria mellonella in response to bacterial challenge and prior to cell disintegration

Hemolin, a member of the immunoglobulin protein superfamily, functions in Lepidoptera as an opsonin in defence against potential pathogens and seems to play a role in tissue morphogenesis. We show that hemolin gene is expressed in several organs of Galleria mellonella larvae, including the nervous system and the silk glands. The expression in the silk glands of the wandering larvae and their isolated abdomens is enhanced within 6 h after an injection of bacteria, lipopolysaccharides, or peptidoglycans. The magnitude of silk gland response to bacterial challenge is similar to that seen in the fat body. A profound rise of hemolin expression without bacterial inoculation occurs in the silk glands of isolated abdomens when they are induced to pupate by a topical application of 20-hydroxyecdysone (20E). The induction of pupation is associated with silk gland programming for disintegration by apoptosis and phagocytosis. Administration of a juvenile hormone agonist prevents pupation and abolishes the stimulatory 20E effect on the hemolin expression. Hemolin protein can be immunodetected in the silk glands as well as in the spun-out cocoon silk. The results suggest that silk glands are a component of the insect immune system and that hemolin may mark the apoptic cells for the elimination by hemocytes.     

Correlated evolution of interacting proteins: looking behind the mirrortree

It has been observed that the evolutionary distances of interacting proteins often display a higher level of similarity than those of noninteracting proteins. This finding indicates that interacting proteins are subject to common evolutionary constraints and constitutes the basis of a method to predict protein interactions known as mirrortree. It has been difficult, however, to identify the direct cause of the observed similarities between evolutionary trees. One possible explanation is the existence of compensatory mutations between partners' binding sites to maintain proper binding. This explanation, though, has been recently challenged, and it has been suggested that the signal of correlated evolution uncovered by the mirrortree method is unrelated to any correlated evolution between binding sites. We examine the contribution of binding sites to the correlation between evolutionary trees of interacting domains. We show that binding neighborhoods of interacting proteins have, on average, higher coevolutionary signal compared with the regions outside binding sites; however, when the binding neighborhood is removed, the remaining domain sequence still contains some coevolutionary signal. In conclusion, the correlation between evolutionary trees of interacting domains cannot exclusively be attributed to the correlated evolution of the binding sites or to common evolutionary pressure exerted on the whole protein domain sequence, each of which contributes to the signal measured by the mirrortree approach.     

Two Crystal Structures of Pneumococcal Pilus Sortase C Provide Novel Insights into Catalysis and Substrate Specificity

The respiratory tract pathogen Streptococcus pneumoniae is a primary cause of morbidity and mortality worldwide. Pili enhance initial adhesion as well as the capacity of pneumococci to cause pneumonia and bacteremia. Pilus-associated sortases (SrtB, SrtC, and SrtD) are involved in the biogenesis of pneumococcal pili, composed of repeating units of RrgB that create the stalk to which the RrgA adhesin and the preferential pilus tip subunit RrgC are covalently associated. Using single sortase-expressing strains, we demonstrate that both pilin-polymerizing sortases SrtB and SrtC can covalently link pili to the peptidoglycan cell wall, a property shared with the non-pilus-polymerizing enzyme SrtD and the housekeeping sortase SrtA. Comparative analysis of the crystal structures of S. pneumoniae SrtC and SrtB revealed structural differences explaining the incapacity of SrtC, but not of SrtB, to incorporate RrgC into the pilus. Accordingly, site-directed mutagenesis of Thr¹⁶⁰ in SrtB to an arginine as in SrtC (Arg¹⁶⁰) partially converted its substrate specificity into that of SrtC. Solving two crystal structures for SrtC suggests that an opening of a flexible lid and a concomitant cysteine rotation are important for catalysis and the activation of the catalytic cysteine of pilus-associated sortases.     

Thermodynamics and kinetics for base pair opening in the DNA decamer duplexes containing cyclobutane pyrimidine dimer

The cyclobutane pyrimidine dimer (CPD) is one of the major classes of cytotoxic and carcinogenic DNA photoproducts induced by UV light. Hydrogen exchange rates of the imino protons were measured for various CPD-containing DNA duplexes to better understand the mechanism for CPD recognition by XPC-hHR23B. The results here revealed that double T·G mismatches in a CPD lesion significantly destabilized six consecutive base pairs compared to other DNA duplexes. This flexibility in a DNA duplex caused at the CPD lesions with double T·G mismatches might be the key factor for damage recognition by XPC-hHR23B.     

Proteomic characterization of sperm radial spokes identifies a novel spoke protein with an ubiquitin domain

Radial spokes are T-shaped protein complexes important for the regulation of axonemal dyneins in eukaryotic cilia and flagella. Using a functional proteomics approach, we identified six spoke proteins in sperm flagella of the ascidian Ciona intestinalis. Many of the domain/motif structures in spoke proteins are commonly found in flagella of both Ciona sperm and Chlamydomonas, but interestingly they often distribute over non-orthologous protein components. A novel 116 kDa protein named CMUB116 has both an ubiquitin domain and an IQ motif. It has orthologs in vertebrates, but not in Chlamydomonas. Furthermore, the results obtained by immunological analysis provide strong indication that CMUB116 is located at the stalk of radial spokes, where it is associated with MORN40.

Structured summary

MINT-7148244: CMUB116 (genbank_protein_gi:BAH59277) and MORN40 (genbank_protein_gi:BAH59284) colocalize (MI:0403) by cosedimentation (MI:0027)MINT-7148179: Ci-RSP3 (uniprotkb:Q8T898) physically interacts (MI:0915) with tubulin alpha (uniprotkb:Q8MVT7), LRR37 (uniprotkb:Q8T896), CMUB116 (genbank_protein_gi:BAH59277), Ci-SRP4/6 (genbank_protein_gi:BAH59283), AK58 (genbank_protein_gi:BAM59278), tubulin beta (genbank_protein_gi:XP_002130315), NDK/DPY26 (genbank_protein_gi:BAH59279), MORN40 (genbank_protein_gi:BAH59284), ARM37 (genbank_protein_gi:BAH59280), NDK/DPY26 (genbank_protein_gi:NP_001161489), LC8 (genbank_protein_gi:BAH59282) and Ci-RSP9 (genbank_protein_gi:NP_001154962) by anti bait coimmunoprecipitation (MI:0006)MINT-7148272: Ci-RSP3 (uniprotkb:Q8T898) and MORN40 (genbank_protein_gi:BAH59284) colocalize (MI:0403) by cosedimentation (MI:0027)     

潘氏细胞研究进展

潘氏细胞是位于小肠腺底部的浆液性腺上皮细胞,其主要特征是细胞顶部有大量粗大的嗜酸性分泌颗粒,内含防御素、溶菌酶、sIgA等多种抗菌物质。表达于潘氏细胞的NOD2、Toll样受体9、肝癌-肠-胰腺／胰腺炎相关蛋白、RegⅢγ、肿瘤坏死因子仅、粒细胞-巨噬细胞集落刺激因子、白介素-17等也是免疫与炎症反应的重要成分。金属硫蛋白、富半胱氨酸肠蛋白、潘氏细胞锌结合蛋白等金属结合蛋白均分布于潘氏细胞,提示潘氏细胞参与金属代谢。潘氏细胞是构成肠黏膜屏障的重要细胞成分。NOD2单核苷酸多态性与克罗恩病有关。潘氏细胞化生常发生于胃、大肠的炎症与肿瘤病变,其病理意义有待于进一步研究。     

Water filtration rate and infiltration/accumulation of low density lipoproteins in 3 different modes of endothelial/smooth muscle cell co-cultures

Using different endothelial/smooth muscle cell co-culture modes to simulate the intimal structure of blood vessels, the water filtration rate and the infiltration/accumulation of LDL of the cultured cell layers were studied. The three cell culture modes of the study were: (i) The endothelial cell monolayer (EC/Φ); (ii) endothelial cells directly co-cultured on the smooth muscle cell monolayer (EC-SMC); (iii) endothelial cells and smooth muscle cells cultured on different sides of a Millicell-CM membrane (EC/SMC). It was found that under the same condition, the water filtration rate was the lowest for the EC/SMC mode and the highest for the EC/Φ mode, while the infiltration/accumulation of DiI-LDLs was the lowest in the EC/Φ mode and the highest in the EC-SMC mode. It was also found that DiI-LDL infiltration/accumulation in the cultured cell layers increased with the increasing water filtration rate. The results from the in vitro model study therefore suggest that the infiltration/accumulation of the lipids within the arterial wall is positively correlated with concentration polarization of atherogenic lipids, and the integrity of the endothelium plays an important role in the penetration and accumulation of atherogenic lipids in blood vessel walls.     

The role of interspecific interference competition in character displacement and the evolution of competitor recognition

The extent to which interspecific interference competition has contributed to character evolution is one of the most neglected problems in evolutionary biology. When formerly allopatric species come into secondary contact, aggressive interactions between the species can cause selection on traits that affect interspecific encounter rates (e.g. habitat preferences, activity schedules), competitor recognition (e.g. colouration, song), and fighting ability (e.g. weaponry, body size). We define agonistic character displacement (ACD) as the process of phenotypic evolution in a population caused by interference competition with one or more sympatric species and which results in shifts in traits that affect the rate, intensity or outcome of interspecific aggression. After clarifying the relationships between ACD and other evolutionary processes that may occur when species come into secondary contact, we develop an individual‐based, quantitative genetic model to examine how traits involved in competitor recognition would be expected to evolve under different secondary contact scenarios. Our simulation results show that both divergence and convergence are possible outcomes, depending on the intensity of interspecific exploitative competition, the costs associated with mutual versus unilateral recognition, and the extent of phenotypic differences prior to secondary contact. We then devise a set of eight criteria for evaluating putative examples of ACD and review the empirical literature to assess the strength of existing evidence and to identify promising avenues for future research. Our literature search revealed 33 putative examples of ACD across insects, fishes, bats, birds, lizards, and amphibians (15 divergence examples; 18 convergence examples). Only one example satisfies all eight criteria for demonstrating ACD, but most case studies satisfy four or more criteria. The current state of the evidence for ACD is similar to the state of the evidence for ecological character displacement just 10 years ago. We conclude by offering suggestions for further theoretical and empirical research on ACD.     

Catalytic resonance scattering spectral determination of ultratrace horseradish peroxidase using rhodamine S

A highly sensitive and selective resonance scattering spectral assay was proposed for the determination of horseradish peroxidase (HRP), based on its catalytic effect on the H₂O₂ oxidation of KI to form I₃^?. The I₃^? combined respectively with rhodamine (Rh) dye such as rhodamine S (RhS), rhodamine 6G (Rh6G), rhodamine B (RhB) and butyl‐rhodamine B (b‐RhB), to form association particles (Rh‐I₃)_n. The four Rh systems all exhibit a stronger resonance scattering (RS) peak at 424 nm. For the RhS, Rh6G, RhB and b‐RhB systems, HRP concentration in the range of 3.2 × 10^?12 to 4.8 × 10^?9, 2 × 10^?11 to 3.2 × 10^?9, 1.6 × 10^?11 to 3.2 × 10^?9 and 1.6 × 10^?11 to 4 × 10^?9 g/mL was linear to its RS intensity at 424 nm, with a detection limit of 2.2 × 10^?12, 2.5 × 10^?12, 4.4 × 10^?12 and 2.6 × 10^?12 g/mL, respectively. This RhS system was most sensitive and stable, and was applied for the determination of HRP in the hepatitis B surface antibody labeling HRP and water samples, with satisfactory results. Copyright © 2009 John Wiley & Sons, Ltd.