Cell Wall Degrading Enzymes in Cuscuta reflexa and Its Hosts

Pectin degrading enzymes, hemicellulose degrading enzyme andcellulose degrading enzymes were studied in Cuscuta reflexaRoxb., its susceptible hosts, Brassica campestris L., Cocciniaindica W. & A. Datura innoxia Mill, Helianthus annuus L.,Holoptelea indica Planch, Lantana camara L., Medicago sativaL., Manihot utilissima Pohl, Petunia hybrida X Hort exvilm,Pisum sativum L., Phaseolus vulgaris L. and Solanum nigrum L.and non-susceptible plants Ipomoea batata Lam. and Solanum tuberosumL. Pectin esterase and polygalacturonase were present in higheramounts in Cuscuta parasitic on P. vulgaris and S. nigrum, whichneeded more time for haustorial establishment. Exo-l, 4-ß-D-glucosidaseactivity was found in Cuscuta but could not be detected in itshosts. Xylanase and cellulase activity of host plants increasedwhile cellobiase activity decreased as a result of infectionby the parasite. Higher pectin esterase, polygalacturonase,xylanase and exo-l, 4-ß-D-glucosidase activities inthe haustorial region of the parasite is likely to bring aboutthe lysis of the cell wall of the host plant and thus facilitatethe penetration of the parasite haustoria into the host sieveelement, which is necessary for the transport of nutrients betweenthe host and the parasite. Key words: Cell wall degrading enzymes, Cuscuta reflexa     

Development of Plastids in Pollen and Tapetum of Rye-grass, Lolium perenne L

Proplastids of both tapetal cells and microsporocytes were presentearly in anther development. Tapetal proplastids differentiated—probablyinto elaioplasts—at late microspore stage. The tapetalcytoplasm was completely resorbed by early tricellular pollenstage. Microspore proplastids differentiated into amyloplastsat early bicellular stage, and were present in both vegetativeand generative cells. In the generative cell, the amyloplastswere ephemeral and apparently degenerated within autophagicvacuoles. Plastids were absent from sperm cells. Vegetativecell amyloplasts increased in number apparently by fission suchthat one amyloplast produced one amyloplast and one proplastidper division. Mature pollen grains were estimated to containbetween 550 and 820 amyloplasts with only one starch granuleper plastid. Elaioplasts, amyloplasts, plastid division, plastid differentiation, starch granules, autophagy, Lolium perenne, Poaceae, rye-grass     

Changes in DNA methylation levels during seed development in <Emphasis Type="Italic">Jatropha curcas</Emphasis>

The antiviral action of natural killer (NK) cells is regulated by a wide repertoire of germ-line encoded membrane receptors which recognize the expression of certain self-molecules on target cells. Among the receptors, killer cell immunoglobulin-like receptor (KIR) which recognizes the expression of human leukocyte antigen (HLA) class I has a predominant role in regulating the effector functions of NK cells, particularly in viral infections. We studied a total of 128 hepatitis B virus (HBV) patients (15 acute, 43 asymptomatic, 27 chronic and 43 with other liver diseases) while attending the Department of Medical Gastroenterology, Government Rajaji Hospital, Madurai, India, and 128 ethnic matched control to find the association between the KIR : HLA genes and differential manifestations of HBV. KIR and its ligand HLA polymorphism were identified by DNA-PCR methods. The activatory receptor KIR-2DS1 was significantly elevated in various disease categories, namely asymptomatic, chronic and other HBV, except acute HBV infection. Whereas, KIR 2DS3 in acute and chronic patients and KIR 2DS5 and 3DS1 in asymptomatic individuals. Among various KIR–HLA combinations, homozygous 2DS2:C1 and individuals with 3DSI:BW4 (OR = 3.23, CI = 1.55–6.7, Pc = 0.02) are associated with HBV asymptomatism, while most of the two domain inhibitory receptors with their ligands showed significant risk in other liver diseases. Further, KIR3DL1 : HLA Bw4Iso80 (OR = 3.89, 95% CI = 1.58–9.55, Pc = 0.004) is related with higher risk for asymptomatic infection when compared with chronic HBV. Thus, the select KIR : HLA alleles and combinations seem to direct the NK cell activities and immune response in different directions resulting in varied symptoms and manifestations in the subgroups of HBV-infected patients studied.     

鲤科鱼蓝黑鲮微卫星位点的种间扩增(英文)

本研究使用105对微卫星引物对7种鲤科鱼类进行跨越种间PCR扩增,共得到14个多态性微卫星位点.其中9个扩增效果较好的位点用于分析来自帕吉勒提河(Bhagirathi, n=20)和戈达瓦里河(Godavari, n=25)的蓝黑鲮(Labeo calbasu)样品的遗传多样性.结果显示,前者在每个位点的平均等位基因数为7.33,而后者为8 1,期望杂合度介于0.795(Bhagirathi)和0.801(Godavari)之间;4个位点MFW11* (Godavari)、R1*(Godavari)、R3* (Bhagirathi) 和 Lr38*(Bhagirathi和Godavari)都表现出明显的杂合子缺失和哈迪温伯格平衡偏离;而任意两位点间都未观测到连锁不平衡现象;位点R3*极可能存在无效等位基因.上述结果表明这些多态性微卫星位点作为共显性标记在蓝黑鲮群体遗传学研究中有着较好的应用前景.     

Glasshouse tests and field selection for heritable resistance to Myzus persicae in sugar beet

A technique is described to assess and select in the field for resistance to Myzus persicae in sugar beet. Lines developed by this method were aphid resistant when compared with commercial cultivars. The resistance was inherited by progeny lines. Variation between beet lines in glasshouse tests suggested segregation of a number of resistance genes with varying effects. Integration of selection for aphid-resistance and agronomic performance during beet breeding is discussed.     

Partial purification and characterization of phospholipase C from Yersinia enterocolitica

About 34% of the strains of Yersinia enterocolitica isolated from raw milk were found to produce lecithinase. A selected strain produced phospholipase C at 22°C and 37°C; production was optimum at 37°C in the stationary phase (14–16 h). A decrease in phospholipase C activity at various storage temperatures (—5°C, 4°C, 37°C) was also observed, although the enzyme was active over a wide range of temperature (5–65°C) and pH (3mD5–7mD5). The phospholipase C was partially purified by ammonium sulphate precipitation and Sephadex column chromatography, and characterized.     

Differential Rates of Uptake of Glucose, Fructose and Sucrose by Pea Stem Protoplasts

Protoplasts from growing regions of etiolated pea stems takeup glucose more rapidly than fructose when supplied for briefperiods at low concentrations. The uptake of the two hexosesis differentially inhibited by galactoac and by reagents thatcurtail ATP synthesis, and uptake of one hexose is not preventedby the other, even at a 100-fold excess. Sucrose uptake is muchslower than that of either hexose and is correlated with theappearance of invertase activity in the medium. Label from [¹⁴C-glc]-sucroseis taken up more rapidly than from [¹⁴C-fru]-sucrose. It isconcluded that these cells take up supplied sucrose only afterhydrolysis to hexoses, which are then absorbed by differentcarrier-mediated processes. Key words: Glucose, fructose, invertase, pea, protoplast, sucrose     

Nitrogen and Carbohydrate Metabolism of Japanese Mint as Affected by Phosphorus Deficiency and Seasonal Variations

The paper presents effects of phosphorus deficiency and seasonal variations on nitrogen and carbohydrate metabolism of Japanese mint (Mentha arvensis L. var. piperascens, Holmes). Mint plants were grown in sand cultures under full nutrition and under phosphorus deficiency conditions during winter and summer. Various nitrogen and sugar fractions were determined in the component parts at specified periods of growth stages. Phosphorus deficiency disturbed the nitrogen metabolism at the stages for amide and amino acid formation, which resulted in an accumulation of carbohydrates. The content of total soluble and total nitrogen was higher and that of insoluble nitrogen was lower in summer as compared with winter plants. Of the soluble fractions, the ammonia, amide and nitrate nitrogen were higher and the ‘rest’ nitrogen lower in winter plants. Nitrate formed the highest bulk of the pool of soluble nitrogen in winter, whereas in summer ‘rest’ nitrogen was most abundant. The content of total sugar in winter plants far exceeded that of summer plants, which was wholly due to increase in sucrose content. Glucose was the predominant reducing sugar in both seasons. However, the summer plants were richer in glucose than those from the winter.