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.     

Changes in the parasitic fish fauna of the Ka?rak-Kum reservoir over a long period

During last few years a tendency for the reduction in the number of parasites of all investigated fishes has been observed. This is connected with the general tendency for the impoverishment of the reservoir flora and fauna, that may be the result of the fluctuations of its water level. Finally this process leads to the reduction in the number of many species of parasites and even to their disappearance.     

Nocodazole inhibits macronuclear infection with Holospora obtusa in Paramecium caudatum

Summary. Holospora obtusa is a Gram-negative bacterium inhabiting the macronucleus of the ciliate Paramecium caudatum. Experimental infection with H. obtusa was carried out under nocodazole treatment. Nocodazole has been shown to cause disassembly of the cytoplasmic microtubules radiating from the cytopharynx and postoral fibers in P. caudatum. Treatment with this drug did not prevent the ingestion of both prey bacteria and H. obtusa, but it reduced the phagosome number and affected cyclosis. In situ hybridization revealed infectious forms of this endobiont very close to the macronucleus, but never inside it. These results indicate that disassembly of microtubules does not impair transportation of the infectious forms of H. obtusa in the cytoplasm, but that it completely blocks the invasion of the nucleus by the bacteria. Correspondence and reprints: Department of Cytology and Histology, Faculty of Biology and Soil Sciences, Saint Petersburg State University, Universitetskaya naberezhnaya 7/9, 199034 Saint Petersburg, Russia.     

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。     

Protective effect of peptide semax the rat heart in acute myocardial infarction

Semax, a member of ACTH-derived peptides family, has been employed in the treatment of acute ischemic stroke in patients. It decreased neurological deficit and reduced NO hyperproduction in the rat brain, caused by acute cerebral hypoperfusion. We suggested that semax is also able to protect rat heart from ischemic damage in acute myocardial infaction (AMI). AMI was induced by left coronary artery occlusion, myocardial ischemic area averaged 30 % of left ventricle. In 2 hours after coronary occlusion, the AMI group developed 11 % reduced mean arterial blood pressure and 48 % increased diastolic blood pressure in left ventricle in comparison with sham-operated control group. However, infusion of either dobutamine, which directly stimulates myocardial contractility, or sodium nitroprusside and phenylephrine, that change vascular resistance and thus cardiac afterload, did not reveal distinctions in hemodynamic parameters between groups. These data indicate absense or only moderate cardiac dysfunction in rats with AMI and are consistent wih morphometrical and histochemical studies that did not detect any necrotic or apoptotic (TUNEL-test) changes in left ventricular cardiomyocytes in spite of development of distinct ischemic disturbances of mitochondria and nuclear in about 50 % of cardiomyocytes in 2 hours after AMI. Semax (150 microg/kg), given i. p. 15 min and 2 hours after coronary occlusion, caused no effect on cardiac function, but completely prevented ischemia-induced ultrastructural changes of cardiomyocytes. This protective effect was accompanied by the ability of peptide to blunt the increase in plasma concentrations of nitrates, observed in AMI group.     

Protective effect of peptide semax (ACTH(4-7)Pro-Gly-Pro) on the rat heart rate after myocardial infarction

Semax, a member of ACTH-derived peptides family, was used in treatment of ischemic stroke in patients. It decreased neurological deficiency and reduced NO hyperproduction in the rat brain caused by acute cerebral hypoperfusion. We suggest that semax is also capable of protecting the rat heart from ischemic damage 28 days after myocardial infarction (MI) induced by left descendent coronary artery occlusion. Semax (150 microg/kg) was given i. p. in the operating day twice: 15 min and 2 hours after coronary occlusion, and once a day for the following 6 days. In 28 days after infarction, the MI group developed cardiac hypertrophy, cell growth was caused mainly by the increase of contractile filaments not supported by the appropriate mitochondrial growth that indicated an impaired energy supply of the cells. Moreover, cardiac hypertrophy was accompanied by decreased mean arterial blood pressure and cardiac contractile function and increased left ventricular end-diastolic pressure. Pharmacological change of cardiac afterload revealed that, in 28 days after MI, the rat heart was not able to change its contractile performance in response to either increase or decrease of systemic blood pressure, and as a result could not maintain its diastolic pressure. All these changes obviously reflect development of heart failure. Semax did not affect cardiac work but partially prevented end-diastolic pressure growth in left ventricle as well as ameliorated cardiomyocyte hypertrophy and disproportionate growth of contractile and mitochondrial apparatus, thus exerting beneficial effect on the left ventricular remodeling and heart failure development late after myocardial infarction.     

Baeocytes in the cyanobacterium <Emphasis Type="Italic">Pleurocapsa</Emphasis> sp.: Characterization of the differentiated cells produced by multiple fission

Electron microscopy of cyanobacterium Pleurocapsa sp. CALU 1126 revealed that multiple fission proceeds by successive binary fissions. The cultivation conditions were determined when the number of baeocytes (products of multiple fission) was comparable with that of macrocytes (products of binary fission), and cell sorting was achieved for the first time. Juvenile baeocytes were shown to differ from macrocytes in: (1) the absence of sheath; (2) the linear-peripheral configuration of their lamellar system; (3) lower content of phycobiliproteins and higher content of carotenoids; (4) the set of PSII polypeptides. Baeocytes can therefore be considered differentiated cells characterized by the uncoupling between energy and biosynthetic metabolism.     

Chromatin morphology and cytokinesis in pleurocapsalean cyanobacteria

Chromatin morphology and cytokinesis are described in the cyanobacterium Pleurocapsa sp. CALU 1126 capable of multiple fission (multiple reproduction of the mother cell, the macrocyte, with the formation of unique reproductive cells, the baeocytes by means of differential interference contrast (DIC) and fluorescence microscopy). Two kinds of chromatin behavior in the cell cycle are revealed, including (1) the formation of numerous chromatin areas prior to their compartmentalization by multiple fission and (2) chromatin condensation in the phase of binary fission and chromatin decondensation in growth period. The cytokinetic essence of multiple fission is shown to consist of successive binary fissions of the macrocyte, while in between, the mother cells (prebaeocytes) do not grow.