Codeinone reductase isoforms with differential stability,efficiency and product selectivity in opium poppy

Codeinone reductase (COR) catalyzes the reversible NADPH‐dependent reduction of codeinone to codeine as the penultimate step of morphine biosynthesis in opium poppy (Papaver somniferum). It also irreversibly reduces neopinone, which forms by spontaneous isomerization in aqueous solution from codeinone, to neopine. In a parallel pathway involving 3‐O‐demethylated analogs, COR converts morphinone to morphine, and neomorphinone to neomorphine. Similar to neopine, the formation of neomorphine by COR is irreversible. Neopine is a minor substrate for codeine O‐demethylase (CODM), yielding morphine. In the plant, neopine levels are low and neomorphine has not been detected. Silencing of CODM leads to accumulation of upstream metabolites, such as codeine and thebaine, but does not result in a shift towards higher relative concentrations of neopine, suggesting a mechanism in the plant for limiting neopine production. In yeast (Saccharomyces cerevisiae) engineered to produce opiate alkaloids, the catalytic properties of COR lead to accumulation of neopine and neomorphine as major products. An isoform (COR‐B) was isolated from opium poppy chemotype Bea's Choice that showed higher catalytic activity than previously characterized CORs, and it yielded mostly neopine in vitro and in engineered yeast. Five catalytically distinct COR isoforms (COR1.1–1.4 and COR‐B) were used to determine sequence–function relationships that influence product selectivity. Biochemical characterization and site‐directed mutagenesis of native COR isoforms identified four residues (V25, K41, F129 and W279) that affected protein stability, reaction velocity, and product selectivity and output. Improvement of COR performance coupled with an ability to guide pathway flux is necessary to facilitate commercial production of opiate alkaloids in engineered microorganisms.     

Change in the Concentration and Tissue localization of Endogenous IAA During the Regeneration of Vascular Tissues After Xylem Removal in Broussonetia papyrifera

Change in the concentration of endogenous IAA was monitored with enzyme-linked immunesorbent assay (ELISA), and IAA localization in the tissues was demonstrated by means of immunogold-silver microscopy, with authors' modification, during the regeneration after removal of xylem in Broussonetia popyrifera (L.) Vent. The stimulation exerted from xylem removal produced a rapid increase of about 70% of the endogenous IAA concentration. However, the concentration decreased during differentiation of the vascular tissues. Although removal of the tree crown inhibited the regeneration of vascular tissues, the change tendency in the concentration of endogenous IAA during the regeneration remained the same as if the tree crown was intact. This suggested that rapid increase of endogenous IAA induced by wounding could be a result from a release of the combined form into free IAA. Tissue-localization showed that there were more silver-grains labelled in the rays, callus and the regenerated differentiating vascular tissue cells than in other tissues. It could suggest that the high concentration of endogenous IAA triggered the dedifferentiation of the vascular tissues after removal of xylem, and the less concentrated IAA flow could promote the initiation and activity of the regenerated cambium.     

Relationship Between Endogenous Ethylene and the Development and Operation of the Alternative Respiratory Pathway in Aged Potato Tuber Slices

The relationship between endogenous ethylene and the development and the operation of the alternative respiration pathway in aged potato (Solanum tuberosum L. ) tuber slices were investigated. During the 24 h aging period under 30 ℃, along with the great increase of the total respiratory rate (Vt) of the slices, the alternative pathway capacity (Valt) developed continuously, and the Valt/Vt values kept increasing as well. Both the alternative pathway activity (ρValt) and its contribution to Vt(ρValt/Vt) also increased gradually before 12 h of aging, but kept constant from 12 h to 24 h. The time course of the endogenous ethylene production of the aged slices was similar to the changing trends of Valt and Valt/Vt, but different from those of ρValt and ρValt/Vt values. ACC and Cu2 + treatment which stimulated ethylene production of the aged slices enhanced their Valt and Valt/ Vt values, Co2 + and Ag+ treatment resulted in a decreased effect. However, all the above treat ments of ethylene-related agents could not alter the continuously decreasing trend of the ρ value of the alternative pathway of the aged slices. And their effects on ρValt and ρValt/Vt values were only observed before 12 h of aging. These results suggested that the endogenous ethylene was essential to the development of the capacity of alternative pathway, but could only slightly influence the operation of the activity of the alternative pathway in aged potato tuber slices.     

团头鲂寄生吸管虫一新种,双泡毛管虫的研究

描述了寄生在团头鲂(Megalobrama amblycephala)鳃上的一吸管虫新种,双泡毛管虫。活体无色透明至淡黄色,正面观为卵圆形至长椭圆形,稍扁平;侧面观为棒状或香肠状,常附着在鳃小片上。身体的表膜中有不明显的细小颗粒。吸管指状,一束,着生在虫体前端,一般有4—8根,最多达23根,收缩时其表面出现明显的螺旋纹8—11个。两个伸缩泡,交替地进行伸缩,彼此间隔约为10μm,位于吸管基部的胞质中。大核短杆状或椭圆形,核膜明显,染色质均匀。小核圆球形。成虫和幼虫没有固着柄,游泳幼虫的纤毛带宽6.0—7.0μm,由7—11行纤毛纹组成,无锥形的钻孔器。       

Effects of ileal endogenous nitrogen losses and dietary amino acid supplementation on nitrogen retention in growing pigs

The relationship between ileal endogenous nitrogen (N) losses and N retention was studied in two experiments with growing pigs of 40 to 60 kg. In Experiment 1, 13 ileal cannulated castrated males were fed diets based on maize starch, containing either soyabean meal (SBM) with a low trypsin inhibitor activity (TIA), a mixture of toasted and untoasted soyabean meal with a high TIA (mSBM), a commercial batch of peas, or rapeseed expeller cake (RC). Ileal endogenous N recovery was measured using the ¹⁵N-isotope dilution technique. Apparent ileal digestibility of crude protein (CP) for the SBM, mSBM, pea and RC diets were 82.8, 72.0, 76.7 and 68.7% (P < 0.05). True ileal CP digestibility for the diets was 96.5, 93.0, 94.0 and 87.5% (P < 0.05), and the recovery of ileal endogenous N was 3.08, 6.01, 4.55 and 5.36 g/kg DMI (P < 0.05). In Experiment 2, sixteen castrated males were used to determine N retention, using almost similar diets as in Experiment 1. The diets contained either SBM, mSBM or peas and were balanced for the contents of apparent ileal digestible (ID) CP (96 g/kg) and ID essential amino acids (EAA; at least 85% of requirement values). The fourth treatment was a diet with mSBM as protein source, but supplemented with EAA to the level of 95% of the requirement values (diet mSBMs). Apparent faecal CP digestibility for the SBM, mSBM, pea and mSBMs diets was 88.6, 87.2, 86.1 and 86.0% (P < 0.05). Urinary N excretion and N retention for these treatments were 0.39, 0.59, 0.40, 0.53 (P < 0.05) and 0.87, 0.80, 0.85, 0.84 g/kg^0.75/day (P < 0.05), respectively. Utilization of dietary ID N for N retention were 79.8, 73.3, 78.2 and 77.6% (P < 0.05), respectively. The study showed that increased ileal endogenous N losses are associated with higher losses of urinary N and with a lower N retention. Supplementation of extra essential AA to a diet causing a relatively high flow of ileal endogenous N, may compensate for the lower N utilization under these conditions, and thus limit effects on N retention.     

Automation of PRM‐dependent D3‐Leu tracer enrichment in HDL to study the metabolism of apoA‐I,LCAT and other apolipoproteins

We developed an automated quantification workflow for PRM‐enabled detection of D3‐Leu labeled apoA‐I in high‐density lipoprotein (HDL) isolated from humans. Subjects received a bolus injection of D3‐Leu and blood was drawn at eight time points over three days. HDL was isolated and separated into six size fractions for subsequent proteolysis and PRM analysis for the detection of D3‐Leu signal from ～0.03 to 0.6% enrichment. We implemented an intensity‐based quantification approach that takes advantage of high‐resolution/accurate mass PRM scans to identify the D3‐Leu 2HM3 ion from non‐specific peaks. Our workflow includes five modules for extracting the targeted PRM peak intensities (XPIs): Peak centroiding, noise removal, fragment ion matching using Δm/z windows, nine intensity quantification options, and validation and visualization outputs. We optimized the XPI workflow using in vitro synthesized and clinical samples of D0/D3‐Leu labeled apoA‐I. Three subjects’ apoA‐I enrichment curves in six HDL size fractions, and LCAT, apoA‐II and apoE from two size fractions were generated within a few hours. Our PRM strategy and automated quantification workflow will expedite the turnaround of HDL apoA‐I metabolism data in clinical studies that aim to understand and treat the mechanisms behind dyslipidemia.     

结核病房医院感染与抗生素使用相关性分析

目的：探讨临床抗菌药物应用与结核病房医院感染严重程度的相关性。方法：分析3年来我院结核病房医院感染209例共计221株病原菌,细菌鉴定采用法国梅里埃ATB细菌鉴定药敏分析仪,药敏试验联合应用微量测定法与K—B纸片法。结果：在221株病原菌中革兰阴性杆菌最多为112株,占50．7％,念珠菌75株,占33．9％。主要致病菌依次为白色念珠菌61株(27．6％),铜绿假单胞菌37株(16．8％),肺炎克雷伯菌25株(10．9％)。药敏试验表明细菌耐药明显增加,大多数革兰阴性杆菌对亚胺培南、阿米卡垦、头孢他啶较敏感,金黄色葡萄球菌对万古霉素100％敏感。每例结核病患者除抗结核药物外平均使用2．67种抗菌药物。结论：结核病房医院感染主要来源于内源性感染,其严重性与抗菌药物大量、重复使用密切相关。     

Classification and nomenclature of endogenous retroviral sequences (ERVs): Problems and recommendations

The genomes of many species are crowded with repetitive mobile sequences. In the case of endogenous retroviruses (ERVs) there is, for various reasons, considerable confusion regarding names assigned to families/groups of ERVs as well as individual ERV loci. Human ERVs have been studied in greater detail, and naming of HERVs in the scientific literature is somewhat confusing not just to the outsider. Without guidelines, confusion for ERVs in other species will also probably increase if those ERVs are studied in greater detail. Based on previous experience, this review highlights some of the problems when naming and classifying ERVs, and provides some guidance for detecting and characterizing ERV sequences. Because of the close relationship between ERVs and exogenous retroviruses (XRVs) it is reasonable to reconcile their classification with that of XRVs. We here argue that classification should be based on a combination of similarity, structural features, (inferred) function, and previous nomenclature. Because the RepBase system is widely employed in genome annotation, RepBase designations should be considered in further taxonomic efforts. To lay a foundation for a phylogenetically based taxonomy, further analyses of ERVs in many hosts are needed. A dedicated, permanent, international consortium would best be suited to integrate and communicate our current and future knowledge on repetitive, mobile elements in general to the scientific community.     

Phylogeny of <Emphasis Type="Italic">Banana Streak Virus</Emphasis> Reveals Recent and Repetitive Endogenization in the Genome of Its Banana Host (<Emphasis Type="Italic">Musa</Emphasis> sp.)

Banana streak virus (BSV) is a plant dsDNA pararetrovirus (family Caulimoviridae, genus badnavirus). Although integration is not an essential step in the BSV replication cycle, the nuclear genome of banana (Musa sp.) contains BSV endogenous pararetrovirus sequences (BSV EPRVs). Some BSV EPRVs are infectious by reconstituting a functional viral genome. Recent studies revealed a large molecular diversity of episomal BSV viruses (i.e., nonintegrated) while others focused on BSV EPRV sequences only. In this study, the evolutionary history of badnavirus integration in banana was inferred from phylogenetic relationships between BSV and BSV EPRVs. The relative evolution rates and selective pressures (d_N/d_S ratio) were also compared between endogenous and episomal viral sequences. At least 27 recent independent integration events occurred after the divergence of three banana species, indicating that viral integration is a recent and frequent phenomenon. Relaxation of selective pressure on badnaviral sequences that experienced neutral evolution after integration in the plant genome was recorded. Additionally, a significant decrease (35%) in the EPRV evolution rate was observed compared to BSV, reflecting the difference in the evolution rate between episomal dsDNA viruses and plant genome. The comparison of our results with the evolution rate of the Musa genome and other reverse-transcribing viruses suggests that EPRVs play an active role in episomal BSV diversity and evolution.