胸腺肽的合成及抗衰老作用研究

我们采用Ｍｅｒｒｉｆｉｌｄ固相法合成了胸腺生成素Ⅱ的活性片段ＴｈｙｍｏｐｏｉｅｔｉｎⅡ３２～３６（Ｔｐ－５）和胸腺素α１的活性片段Ｔｈｙｍｏｓｉｎ２３～２７（（Ｌｙｓ２３）α１－５）,用０．１,１,１０,１００,１０００ｕｇ／ｋｇ体重的Ｔｐ－５和（Ｌｙｓ２３）α１－５分别腹腔注射小鼠,连续１０天,能使小鼠肝、脑、脾和胸腺组织中丙二醛含量显著降低,可以促进免疫活性和抑制体内脂质过氧化物的生成,最适剂量集中在１～１００μｇ／ｋｇ体重,Ｐ＜０．０１。     

Clinical value of (18)F-FDG PET/CT in postoperative monitoring for patients with colorectal carcinoma

Objective: To evaluate the clinical value of ¹⁸F-FDG PET/CT in postoperative monitoring for patients with colorectal carcinoma. Methods: 66 postoperative patients with colorectal carcinoma underwent whole-body FDG PET/CT. The final histopathological and formal clinical follow-up findings were used as gold standard to determine the sensitivity and specificity of FDG PET/CT and enhanced CT of the same periods. Results: The sensitivity and specificity of FDG PET/CT in detecting recurrence are 96.30%, 94.87% (while enhanced CT are 70.37% and 87.18% respectively). The sensitivity and specificity in detecting metastasis are 95.35%, 82.61% (enhanced CT are 61.90%, 75.00%). SUVmax was significantly higher in malignant lesions [range 4.16–22.00, mean ± standard deviation (x ± s) 8.06 ± 4.30] than in benign ones (range1.18–6.25, x ± s 2.82 ± 1.02). Conclusion: At present, whole-body ¹⁸F-FDG PET/CT is an advanced diagnostic imaging technique in detecting loco-regional recurrence and metastasis in postoperative patients with colorectal carcinoma for its higher sensitivity and specificity.     

The Temporal Scaling of Bacterioplankton Composition: High Turnover and Predictability during Shrimp Cultivation

The spatial distribution of microbial communities has recently been reliably documented in the form of a distance–similarity decay relationship. In contrast, temporal scaling, the pattern defined by the microbial similarity–time relationships (STRs), has received far less attention. As a result, it is unclear whether the spatial and temporal variations of microbial communities share a similar power law. In this study, we applied the 454 pyrosequencing technique to investigate temporal scaling in patterns of bacterioplankton community dynamics during the process of shrimp culture. Our results showed that the similarities decreased significantly (P?=?0.002) with time during the period over which the bacterioplankton community was monitored, with a scaling exponent of w?=?0.400. However, the diversities did not change dramatically. The community dynamics followed a gradual process of succession relative to the parent communities, with greater similarities between samples from consecutive sampling points. In particular, the variations of the bacterial communities from different ponds shared similar successional trajectories, suggesting that bacterial temporal dynamics are predictable to a certain extent. Changes in bacterial community structure were significantly correlated with the combination of Chl a, TN, PO₄ ^3-, and the C/N ratio. In this study, we identified predictable patterns in the temporal dynamics of bacterioplankton community structure, demonstrating that the STR of the bacterial community mirrors the spatial distance–similarity decay model.     

Robust Prediction of t‐Year Survival with Data from Multiple Studies

Summary Recently meta‐analysis has been widely utilized to combine information across multiple studies to evaluate a common effect. Integrating data from similar studies is particularly useful in genomic studies where the individual study sample sizes are not large relative to the number of parameters of interest. In this article, we are interested in developing robust prognostic rules for the prediction of t ‐year survival based on multiple studies. We propose to construct a composite score for prediction by fitting a stratified semiparametric transformation model that allows the studies to have related but not identical outcomes. To evaluate the accuracy of the resulting score, we provide point and interval estimators for the commonly used accuracy measures including the time‐specific receiver operating characteristic curves, and positive and negative predictive values. We apply the proposed procedures to develop prognostic rules for the 5‐year survival of breast cancer patients based on five breast cancer genomic studies.     

PMS‐1077, a PAF antagonist,induced differentiation of HL‐60 cells with its novel activity

The cell differentiation‐inducing effect of 2‐N,N‐diethylaminocarbonyloxymethyl‐1 ‐diphenylmethyl‐4‐(3,4,5‐trimethoxybenzoyl) piperazine, hydrochloride (PMS‐1077) was determined in human leukaemic HL‐60 cells with profiling of cell proliferation, analysis of cell cycling, characterization of expression of various CD molecules and determination of phagocytotic activity of differentiated HL‐60 cells. After treatment with PMS‐1077, HL‐60 cells exhibited a decreased cell viability during which cell cycle was arrested in G₀‐/G₁‐phase. Flow cytometric analysis showed CD11b and CD14 were up‐regulated, whereas CD15 was unaffected. Together with the finding that PMS‐1077‐treated HL‐60 cells exhibited activities of differentiation by examining their ability of phagocytosing latex beads, an antiproliferative effect and a differentiation‐inducing role were determined for PMS‐1077 in HL‐60 cells.     

Nitrogen cycling in forest soils across climate gradients in Eastern China

A ¹⁵N tracing study was carried out to investigate the potential gross nitrogen (N) dynamics in thirteen forest soils in Eastern China ranging from temperate to tropical zones (five coniferous forests, six deciduous broad-leaf forests, one temperate mixed forest, one evergreen broad-leaf forests ecosystems), and to identify the major controlling factors on N cycling in these forest ecosystems. The soil pH ranged from 4.3 to 7.9 and soil organic carbon (SOC) ranged from 6.6 g?kg^?1 to 83.0 g?kg^?1. The potential gross N transformation rates were quantified by ¹⁵N tracing studies where either the ammonium or nitrate pools were ¹⁵N labeled in parallel treatments. Gross mineralization rates ranged from 0.915 μg N g^?1 soil day^?1 to 2.718 μg N g^?1 soil day^?1 in the studied forest soils. The average contribution of labile organic-N (M _Nlab ) to total gross mineralization (M _Nrec +M _Nlab ) was 86% (58% to 99%), indicating that turnover of labile organic N plays a dominant role in the studied forest ecosystems. The gross mineralization rates in coniferous forest soils were significantly lower (ranging between 0.915 and 1.228 μg N g^?1 soil day^?1) compared to broad-leaf forest soils (ranging from 1.621 to 2.718 μg N g^?1 soil day^?1) (p?<?0.01). Thus, the dominant vegetation may play an important role in regulating soil N mineralization. Nitrate production (nitrification) occurred via two pathways, oxidation of NH ₄ ⁺ and organic N the forest soils. Correlations with soil pH indicated that this is a key factor controlling the oxidation of NH ₄ ⁺ and organic N in theses forest ecosystems. NH ₄ ⁺ oxidation decreased with a decline in pH while organic N oxidation increased. The climatic conditions (e.g. moisture status) at the various sites governed the NO ₃ ^? -N consumption processes (dissimilatory NO ₃ ^? reduction to NH ₄ ⁺ (DNRA) or immobilization of NO ₃ ^? ). Total NO ₃ ^? consumption and the proportion of total NO ₃ ^? consumption to total NO ₃ ^? production decreased with an increase in the drought index of ecosystems, showing that strong interactions appear to exist between climatic condition (e.g. the drought index), N mineralization and the rate of DNRA. Interactions between vegetation, climatic conditions govern internal N cycling in these forests soils.     

Microbial Communities and Functional Genes Associated with Soil Arsenic Contamination and the Rhizosphere of the Arsenic-Hyperaccumulating Plant Pteris vittata L.

To understand how microbial communities and functional genes respond to arsenic contamination in the rhizosphere of Pteris vittata, five soil samples with different arsenic contamination levels were collected from the rhizosphere of P. vittata and nonrhizosphere areas and investigated by Biolog, geochemical, and functional gene microarray (GeoChip 3.0) analyses. Biolog analysis revealed that the uncontaminated soil harbored the greatest diversity of sole-carbon utilization abilities and that arsenic contamination decreased the metabolic diversity, while rhizosphere soils had higher metabolic diversities than did the nonrhizosphere soils. GeoChip 3.0 analysis showed low proportions of overlapping genes across the five soil samples (16.52% to 45.75%). The uncontaminated soil had a higher heterogeneity and more unique genes (48.09%) than did the arsenic-contaminated soils. Arsenic resistance, sulfur reduction, phosphorus utilization, and denitrification genes were remarkably distinct between P. vittata rhizosphere and nonrhizosphere soils, which provides evidence for a strong linkage among the level of arsenic contamination, the rhizosphere, and the functional gene distribution. Canonical correspondence analysis (CCA) revealed that arsenic is the main driver in reducing the soil functional gene diversity; however, organic matter and phosphorus also have significant effects on the soil microbial community structure. The results implied that rhizobacteria play an important role during soil arsenic uptake and hyperaccumulation processes of P. vittata.Arsenic (As) is an abundant and widespread trace metalloid element present in virtually all environmental media and is well known to be carcinogenic even at low levels (24). Arsenic contaminations in soil and groundwater have been reported in many parts of the world (2, 29, 34). Recently, in parts of Asia, including China, chronic drinking of arsenic-contaminated groundwater has caused endemic arsenicosis, which has become a major threat to public health (36). Soil arsenic contamination also affects the physiology, growth, and grain quality of crops. For example, high arsenic concentrations were found in rice seeds from Chenzhou, Hunan province, which exceeded the maximal permissible limit of 0.5 mg/kg (dry weight) (21). Hence, remediation of arsenic-contaminated soil and water is one of the major challenges in environmental science and public health. Low-cost, efficient, and environmentally friendly remediation technologies to remove arsenic from contaminated soil and water are urgently needed.Phytoremediation, the use of plants to restore contaminated soil, has attracted great attention recently. A pivotal step toward the phytoremediation of arsenic-contaminated soils is the discovery of the arsenic hyperaccumulator Pteris vittata L. (Chinese brake fern), which possesses high arsenic tolerance and produces a large biomass. This plant species holds great promise for the phytoremediation of arsenic-contaminated soils. It was shown previously that the leaflets of P. vittata were able to accumulate about 100-fold of arsenic from soils (22). Plant arsenic uptake depends mainly on the arsenic source and bioavailability (25). P. vittata remediates arsenic contamination mainly by taking up arsenate [As(V)] via phosphate transport systems, whereas arsenite [As(III)] is very slowly taken up by P. vittata, at 1/10 of the rate of that for arsenate in the absence of phosphate (41). However, the uptake mechanisms still remain largely unknown.Microorganisms play a crucial role in arsenic geochemical cycling through microbial transformation processes, including reduction, oxidation, and methylation (2, 11, 31, 33, 40). Although the impacts of microbial metabolisms were previously reported to be associated with arsenic cycling of soil and water (7, 29), little is known about how rhizobacterial communities of P. vittata respond to arsenic. Recently, we found that inoculating arsenic resistance bacteria increased the arsenic accumulation efficiency of P. vittata by 13 to 110% (46). Therefore, rhizobacteria may play an important role during arsenic uptake and accumulation processes by P. vittata. Thus, it is important to elucidate the microbially diverse populations and functional genes associated with arsenic mobility and transport in the P. vittata rhizosphere. However, to fully understand the ecology of such complex rhizosphere-contaminated soils, it is necessary to analyze different microbial populations simultaneously.Our hypothesis is that the arsenic-hyperaccumulating ability of P. vittata is due to the interactions among plants, rhizobacteria, and arsenic. A study of microbial communities present in the plant rhizosphere is important to illustrate the mechanisms of arsenic hyperaccumulation in P. vittata. Thus, the objectives of this research were to understand how microbial metabolic diversities, communities, and functional genes/relative abundances were affected by soil arsenic contamination and the P. vittata rhizosphere environment. To determine the soil microbial metabolic diversity, the Biolog system (Biolog, Carlsbad, CA) was used to analyze the sole-carbon-source-utilizing capabilities of the soil microbial communities. For functional gene analysis, a high-density, sensitive, oligonucleotide-based microarray (GeoChip 3.0) was used. GeoChip-based technologies have revealed the structure, metabolic activity, and dynamics of microbial communities from complex environments, such as soil, sediments, and groundwater (10, 38, 39, 45, 48). Our results provide evidence that changes of microbial community structure, functional gene distribution, and microbial metabolic diversity are associated with the soil arsenic level and the rhizosphere effect of P. vittata and suggest that plant phytoremediation is an interactive process among plants, microorganisms, and soil contaminants.     

Myristoylation-regulated direct interaction between calcium-bound calmodulin and N-terminal region of pp60v-src

pp60v-src tyrosine protein kinase was suggested to interact with Ca2+-bound calmodulin (Ca2+/CaM) through the N-terminal region based on its structural similarities to CAP-23/NAP-22, a myristoylated neuron-specific protein, whose myristoyl group is essential for interaction with Ca2+/CaM; (1) the N terminus of pp60v-src is myristoylated like CAP-23/NAP-22; (2) both lysine residues are required for the myristoylation-dependent interaction and serine residues that are thought to regulate the interaction through the phosphorylations located in the N-terminal region of pp60v-src. To verify this possibility, we investigated the direct interaction between pp60v-src and Ca2+/CaM using a myristoylated peptide corresponding to the N-terminal region of pp60v-src. The binding assay indicated that only the myristoylated peptide binds to Ca2+/CaM, and the non-myristoylated peptide is not able to bind to Ca2+/CaM. Analyses of the binding kinetics revealed two independent reactions with the dissociation constants (KD) of 2.07 x 10(-9)M (KD1) and 3.93 x 10(-6)M (KD2), respectively. Two serine residues near the myristoyl moiety of the peptide (Ser2, Ser11) were phosphorylated by protein kinase C in vitro, and the phosphorylation drastically reduced the interaction. NMR experiments indicated that two molecules of the myristoylated peptide were bound around the hydrophobic clefts of a Ca2+/CaM molecule. The small-angle X-ray scattering analyses showed that the size of the peptide-Ca2+/CaM complex is 2-3A smaller than that of the known Ca2+/CaM-target molecule complexes. These results demonstrate clearly the direct interaction between pp60v-src and Ca2+/CaM in a novel manner different from that of known Ca2+/CaM, the target molecules, interactions.     

Dynamics of dendritic spines and their afferent terminals: spines are more motile than presynaptic boutons

Previous work has established that dendritic spines, sites of excitatory input in CNS neurons, can be highly dynamic, in later development as well as in mature brain. Although spine motility has been proposed to facilitate the formation of new synaptic contacts, we have reported that spines continue to be dynamic even if they bear synaptic contacts. An outstanding question related to this finding is whether the presynaptic terminals that contact dendritic spines are as dynamic as their postsynaptic targets. Using multiphoton time-lapse microscopy of GFP-labeled Purkinje cells and DiI-labeled granule cell parallel fiber afferents in cerebellar slices, we monitored the dynamic behavior of both presynaptic terminals and postsynaptic dendritic spines in the same preparation. We report that while spines are dynamic, the presynaptic terminals they contact are quite stable. We confirmed the relatively low levels of presynaptic terminal motility by imaging parallel fibers in vivo. Finally, spine motility can occur when a functional presynaptic terminal is apposed to it. These analyses further call into question the function of spine motility, and to what extent the synapse breaks or maintains its contact during the movement of the spine.     

Response of host–bacterial colonization in shrimp to developmental stage,environment and disease

The host‐associated microbiota is increasingly recognized to facilitate host fitness, but the understanding of the underlying ecological processes that govern the host–bacterial colonization over development and, particularly, under disease remains scarce. Here, we tracked the gut microbiota of shrimp over developmental stages and in response to disease. The stage‐specific gut microbiotas contributed parallel changes to the predicted functions, while shrimp disease decoupled this intimate association. After ruling out the age‐discriminatory taxa, we identified key features indicative of shrimp health status. Structural equation modelling revealed that variations in rearing water led to significant changes in bacterioplankton communities, which subsequently affected the shrimp gut microbiota. However, shrimp gut microbiotas are not directly mirrored by the changes in rearing bacterioplankton communities. A neutral model analysis showed that the stochastic processes that govern gut microbiota tended to become more important as healthy shrimp aged, with 37.5% stochasticity in larvae linearly increasing to 60.4% in adults. However, this defined trend was skewed when disease occurred. This departure was attributed to the uncontrolled growth of two candidate pathogens (over‐represented taxa). The co‐occurrence patterns provided novel clues on how the gut commensals interact with candidate pathogens in sustaining shrimp health. Collectively, these findings offer updated insight into the ecological processes that govern the host–bacterial colonization in shrimp and provide a pathological understanding of polymicrobial infections.