High throughput screening of hydrolytic enzymes from termites using a natural substrate derived from sugarcane bagasse

Background

Short rotation coppice willow is a potential lignocellulosic feedstock in the United Kingdom and elsewhere; however, research on optimising willow specifically for bioethanol production has started developing only recently. We have used the feedstock Salix viminalis × Salix schwerinii cultivar 'Olof' in a three-month pot experiment with the aim of modifying cell wall composition and structure within the stem to the benefit of bioethanol production. Trees were treated for 26 or 43 days with tension wood induction and/or with an application of the cellulose synthesis inhibitor 2,6-dichlorobenzonitrile that is specific to secondary cell walls. Reaction wood (tension and opposite wood) was isolated from material that had received the 43-day tension wood induction treatment.

Results

Glucan content, lignin content and enzymatically released glucose were assayed. All measured parameters were altered without loss of total stem biomass yield, indicating that enzymatic saccharification yield can be enhanced by both alterations to cell wall structure and alterations to absolute contents of either glucan or lignin.

Conclusions

Final glucose yields can be improved by the induction of tension wood without a detrimental impact on biomass yield. The increase in glucan accessibility to cell wall degrading enzymes could help contribute to reducing the energy and environmental impacts of the lignocellulosic bioethanol production process.     

Halofuginone has anti-proliferative effects in acute promyelocytic leukemia by modulating the transforming growth factor beta signaling pathway

Promyelocytic leukemia-retinoic acid receptor alpha (PML-RARα) expression in acute promyelocytic leukemia (APL) impairs transforming growth factor beta (TGFβ) signaling, leading to cell growth advantage. Halofuginone (HF), a low-molecular-weight alkaloid that modulates TGFβ signaling, was used to treat APL cell lines and non-obese diabetic/severe combined immunodeficiency (NOD/SCID) mice subjected to transplantation with leukemic cells from human chorionic gonadotrophin-PML-RARα transgenic mice (TG). Cell cycle analysis using incorporated bromodeoxyuridine and 7-amino-actinomycin D showed that, in NB4 and NB4-R2 APL cell lines, HF inhibited cellular proliferation (P<0.001) and induced apoptosis (P = 0.002) after a 24-hour incubation. Addition of TGFβ revealed that NB4 cells were resistant to its growth-suppressive effects and that HF induced these effects in the presence or absence of the cytokine. Cell growth inhibition was associated with up-regulation of TGFβ target genes involved in cell cycle regulation (TGFB, TGFBRI, SMAD3, p15, and p21) and down-regulation of MYC. Additionally, TGFβ protein levels were decreased in leukemic TG animals and HF in vivo could restore TGFβ values to normal. To test the in vivo anti-leukemic activity of HF, we transplanted NOD/SCID mice with TG leukemic cells and treated them with HF for 21 days. HF induced partial hematological remission in the peripheral blood, bone marrow, and spleen. Together, these results suggest that HF has anti-proliferative and anti-leukemic effects by reversing the TGFβ blockade in APL. Since loss of the TGFβ response in leukemic cells may be an important second oncogenic hit, modulation of TGFβ signaling may be of therapeutic interest.     

Proteolytic activity in enzymatic extracts from Carica papaya L. cv. Maradol harvest by-products

Proteolytic activity and the cysteine protease profile were determined for enzymatic extracts (EE) from Carica papaya L. cv. Maradol harvest by-products (stems, unripe fruit, petioles and leaves). The proportion of each by-product type in the sampled plantation was calculated. Polypeptide bands were identified by SDS–PAGE for each EE and molecular weight calculated for the cysteine proteases. Leaf and fruit tissue had the highest protein contents of the by-products. Leaf tissue also produced the highest total EE yield. All the SDS–PAGE gels for the EE’s exhibited an approximately 23 kDa band probably corresponding to papain. The zymography profiles of the EE’s were similar, with bands at approximately >202.8, 76.8, 55.4 and 46.5 kDa. The fruit EE had the highest specific proteolytic activity and the leaf EE the lowest. Fruit and stem by-products are the most promising for proteolytic enzyme extraction.     

Wave-energy patterns in carotid, brachial, and radial arteries: a noninvasive approach using wave-intensity analysis

The study of wave propagation at different points in the arterial circulation may provide useful information regarding ventriculoarterial interactions. We describe a number of hemodynamic parameters in the carotid, brachial, and radial arteries of normal subjects by using noninvasive techniques and wave-intensity analysis (WIA). Twenty-one normal adult subjects (14 men and 7 women, mean age 44 +/- 6 yr) underwent applanation tonometry and pulsed-wave Doppler studies of the right common carotid, brachial, and radial arteries. After ensemble averaging of the pressure and flow-velocity data, local hydraulic work was determined and a pressure-flow velocity loop was used to determine local wave speed. WIA was then applied to determine the magnitude, timings, and energies of individual waves. At all sites, forward-traveling (S) and backward-traveling (R) compression waves were observed in early systole. In mid- and late systole, forward-traveling expansion waves (X and D) were also seen. Wave speed was significantly higher in the brachial (6.97 +/- 0.58 m/s) and radial (6.78 +/- 0.62 m/s) arteries compared with the carotid artery (5.40 +/- 0.34 m/s; P < 0.05). S-wave energy was greatest in the brachial artery (993.5 +/- 87.8 mJ/m2), but R-wave energy was greatest in the radial artery (176.9 +/- 19.9 mJ/m2). X-wave energy was significantly higher in the brachial and radial arteries (176.4 +/- 32.7 and 163.2 +/- 30.5 mJ/m2, respectively) compared with the carotid artery (41.0 +/- 9.4 mJ/m2; P < 0.001). WIA illustrates important differences in wave patterns between peripheral arteries and may provide a method for understanding ventriculo-arterial interactions in the time domain.     

Structural model of the amino propeptide of collagen XI alpha1 chain with similarity to the LNS domains

Fibrillar collagens are the principal structural molecules of connective tissues. The assembly of collagen fibrils is regulated by quantitatively minor fibrillar collagens, types V and XI. A unique amino-terminal propeptide domain of these collagens has been attributed this regulatory role. The structure of the amino terminal propeptide has yet to be determined. Low sequence similarity necessitated a secondary structure-based method to carry out homology modeling based upon the determined structure of LNS family members, named for a common structure in the laminin LG5 domain, the neurexin 1B domain and the sex hormone binding globulin. Distribution of amino acids within the model suggested glycosaminoglycan interaction and calcium binding. These activities were tested experimentally. Sequence analyses of existing genes for collagens indicate that 16 known collagen alpha chains may contain an LNS domain. A similar approach may prove useful for structure/function studies of similar domains in other collagens with similar domains. This will provide mechanistic details of the organization and assembly of the extracellular matrix and the underlying basis of structural integrity in connective tissues. The absolute requirement for collagen XI in skeletal growth is indicated by collagen XI deficiencies such as chondrodystrophies found in the cho/cho mouse and in humans with Stickler syndrome.     

Curvature and tortuosity of the superficial femoral artery: a possible risk factor for peripheral arterial disease.

Atherosclerosis in the superficial femoral artery (SFA) resulting in peripheral arterial disease is more common in men than women and shows a predilection for the region of the adductor canal. Blood flow patterns are related to development of atherosclerosis, and we investigated if curvature and tortuosity of the femoral artery differed between young men and women and if differences resulted in adverse flow patterns. Magnetic resonance imaging (MRI) and computational fluid dynamics (CFD) were combined in 18 young adult volunteers (9 men) to assess the relationship of flow features to likely sites of future atherosclerosis formation. Subjects underwent MRI of the right SFA, three-dimensional vascular geometry was reconstructed, and measures of tortuosity and curvature were calculated. Tortuosity and curvature were significantly greater for men than women, and this was related to increased body surface area, body mass index, or weight in men. In both sexes, "tortuosity" increased from the midthigh to the popliteal fossa. The greatest curvature was found within the distal quarter of the SFA. CFD modeling was undertaken on MRI-based reconstructions of the SFA. Wall shear stresses (WSS) were extracted from the computations. WSS showed greater spatial variation in the men than in the women, and the men exhibited lower mean WSS. These data indicate that sex differences related to body size and anatomical course of the femoral artery may contribute to the enhanced risk of focal atherosclerosis in the adductor canal.     

实验动物皮肤病原真菌检测方法的改良

目的对实验动物皮肤病原真菌2种培养方法进行了比较。方法将采集到的3只皮肤真菌感染病兔样品经由沙氏平皿法和沙氏试管斜面培养法分别进行培养。结果在3只真菌感染病兔中应用试管斜面法我们只检测到1例皮肤病原真菌阳性,而采用沙氏平皿法3例阳性全部检出。结论结合临床检测经验,我们认为本研究的沙氏平皿法优于沙氏试管斜面法,在实验动物皮肤病原真菌常规检测中具有推广应用价值。     

链脲佐菌素诱导长爪沙鼠Ⅰ型糖尿病模型的实验研究

目的探讨链脲佐菌素(STZ)诱导长爪沙鼠Ⅰ型糖尿病模型的可能性,并观察模型动物早期肾脏损害情况。方法雄性长爪沙鼠96只,随机分为正常对照组(NC组)、模型组1(DM1组)、模型组2(DM2组),DM1及DM2组沙鼠分别一次性腹腔注射100 mg/kg、200 mg/kg STZ,NC组注射等量柠檬酸盐缓冲溶液。注射STZ后1、2、4、6周末,分别监测沙鼠一般情况,血糖、胰岛素等血清学指标和尿液指标,并处死沙鼠进行胰腺和肾脏组织的病理学检查。结果注射STZ 24 h后,DM2组及DM1组部分沙鼠逐渐出现典型的"三多一少"症状,随着病程的发展,DM2组沙鼠持续高血糖,DM1组沙鼠血糖值与NC组差异有显著性(P0.05),但有下降趋势;DM2组沙鼠胰岛素显著性降低(P0.05),其他血清学指标及尿液指标均显著性升高(P0.05),DM1组沙鼠各指标差异无显著性。DM2组沙鼠及DM1组少数沙鼠胰腺组织中可见胰岛β细胞减少、空泡样变性等变化,DM2组沙鼠肾脏组织中出现肾小球基质增多,毛细血管襻扩张等病变,DM1组沙鼠肾脏组织未见明显变化。结论 STZ 200 mg/kg可成功诱导长爪沙鼠Ⅰ型糖尿病模型,在病程早期沙鼠肾脏结构和功能已经发生改变。     

High pressure-induced changes in bovine milk proteins: a review

High pressure (HP)-induced changes in the proteins of bovine milk have become an area of considerable research interest in recent years; as a result, there is now a detailed understanding of the effects of HP on casein micelles and whey proteins. HP treatment at pressures >400 or >100 MPa denatures the two most abundant whey proteins, alpha-lactalbumin (alpha-la) and beta-lactoglobulin (beta-lg), respectively. The majority of denatured beta-lg in HP-treated milk associates with the casein micelles, although some denatured beta-lg remains in the serum phase or is attached to the milk fat globule membrane; HP-denatured alpha-la is also associated with the milk fat globules. Casein micelles are disrupted on treatment at pressures >200 MPa; the rate and extent of micellar disruption increases with pressure and is probably due to the increased solubility of calcium phosphate with increasing pressure. On prolonged treatment at 250-300 MPa, reassociation of micellar fragments occurs through hydrophobic bonding; this process does not occur at a pressure >300 MPa, leading to considerably smaller micelles in such milk. As a result of HP-induced changes, the size, number, hydration, composition and light-scattering properties of casein micelles in HP-treated milk differ considerably from those in untreated milk.