Plant–soil feedback during biological invasions: effect of litter decomposition from an invasive plant (Sphagneticola trilobata) on its native congener (S. calendulacea)

生物入侵过程中的植物-土壤反馈：一种入侵植物的凋落物分解对其本地近缘植物的影响 植物入侵可通过正或负的植物-土壤反馈效应改变土壤的生物和非生物性质,从而影响入侵栖息地的土壤理化性质。许多入侵物种的凋落物分解可增加土壤养分,降低本地植物多样性,并导致进一步的植物入侵。关于入侵植物凋落物在不同土壤类型及深度分解及反馈效应的研究依然很少。本研究旨在明确入侵植物南美蟛蜞菊(Sphagneticola trilobata)凋落物在不同土壤类型和不同土壤深度条件下的分解情 况及其对本地近缘植物蟛蜞菊(S. calendulacea)生理生长的影响。将装有南美蟛蜞菊凋落物的尼龙袋加入到不同深度(即0、2、4 和6 cm)的砂土、营养土和粘土中,经6个月的分解后,回收凋落物袋并计算分解速率,随后在凋落物分解处理后的土壤中种植本地蟛蜞菊,并在生长期结束时测量其生理生态指标。研究结果表明,所有处理土壤类型中,凋落物在土壤深度为2和4 cm处分解后显著增加了土壤养分,而对本 地蟛蜞菊的叶片叶绿素、叶氮含量等生长指标表现为负效应。因此,入侵植物南美蟛蜞菊凋落物分解对土壤养分表现为正的反馈效应,而对本地植物蟛蜞菊的生长表现为负效应。我们的研究结果还表明,入侵植物的凋落物分解对土壤和本地物种的影响还因凋落物分解所在的土壤深度而显著不同。未来的研究应侧重于入侵栖息地中更多本地和入侵物种的植物-土壤反馈效应,以及更多土壤类型和土壤深度的入侵植物凋落物效应。     

Detection and identification of phytoplasma associated with witches’ broom and little leaf disease in Arundo donax: first report from India

During the survey of two successive years 2012–2013, in nearby places of Gorakhpur districts, Uttar Pradesh, India, Arundo donax plants were found to be exhibiting witches’ broom, excessive branching accompanied with little leaf symptoms with considerable disease incidence. Nested PCR carried out with universal primers pair R16F2n/R16R2 employing the PCR (P1/P7) product as a template DNA (1:20) resulted in expected size positive amplification ~1.2 kb in all symptom-bearing plants suggested the association of phytoplasma with witches’ broom disease of Narkat plants. BLASTn analysis of the 16S rRNA gene sequence showed the highest (99%) sequence identity with Candidatus phytoplasma asteris (16SrI group). In phylogenetic analysis, the sequence data showed close relationships with the members of 16SrI phytoplasma and clustered within a single clade of 16SrI group and closed to B subgroup representatives. This is a first report of 16Sr I-B group phytoplasma associated with witches’ broom accompanied with little leaf disease of Narkat in India.     

NADPH-cytochrome-c-reductase: Changes in specific activity in gypsy moth larvae

NADPH-cytochrome-c-reductase from guts of gypsy moth, Porthetria dispar, oxidized NADPH at the following rates: 11·6, 41·9, and 57·6 nmol/30 min per 0·6 mg protein, in the third, fourth and fifth instar, respectively. The increase in specific activity may be due to a natural induction process controlled by materials in the food. This could also explain the observed decreases just prior to ecdysis at which time the larvae have ceased feeding.     

Regulation of the synthesis of nucleoside catabolic enzymes in Escherichia coli: Further analysis of a deo OC mutant strain

Summary Four genes, deoA, deoB, deoC, and deoD, involved in the synthesis of nucleoside and deoxynucleoside catabolic enzymes, are located contiguously in the order C-A-B-D on the linkage map of E. coli. They constitute two overlapping operons, one transcribing all the four genes and the other deoB and deoD. To the left of deoC are located two promoter-operator regions in the order deoPO-cytPO. They are involved in controlling the expression of the tetracistronic mRNA. For efficient binding of RNA polymerase at the cytPO site the cAMP+CRP complex is required, whereas binding of RNA polymerase at the deoPO site is independent of this complex. Evidence is available for the existence of yet another controlling site, PO-3, located between deoA and deoB; this controls the expression of deoB and deoD. Both the operons are transcribed in a clockwise direction. An operator constitutive (O ^c) type mutant affecting the synthesis of all four deo enzymes has been analysed. Because of this mutation the strain has become insensitive to catabolite repression. The results confirm the order of the gene in the controlling region to be deoPO-cytPO and the mutation, previously analysed as a deletion, appears to have deleted cytPO deoC region of the chromosome.     

IUB commission of editors of biochemical journals the citation of bibliographic references in biochemical journals recommendations (1971)

A pentose-rich acidic glycoprotein was isolated from protease digested bovine vitreous humor by fractionation on an AG1-X2 column using NaCl solution gradient.The material eluted at 0.35 M NaCl (glycoprotein) was electrophoretically heterogeneous at pH 8.6 after partial purification on Sephadex G-25. Gel filtration on G-100 resolved the glycoprotein into two fractions. These fractions differ in molecular weight; mol. wt approx. 95 000 material consisted of two components on electrophoresis and mol. wt approx. 28 000 material showed only a single component on electrophoresis. The lower molecular weight component was re-chromatographed on Sephadex G-100 yielding a single orcinol positive component which gave a homogeneous band on gel electrophoresis.Quantitative analysis of this material gave 30% protein, 7.0% pentose, 18.7% glucosamine, 9.2% galactosamine, 10.9% hexuronic acid and 16.1% hexose.Treatment with 0.5 M NaOH at 20°C for 24 h resulted in a 50% decrease in the threonine content suggesting the possible involvement of this amino acid in the protein-carbohydrate linkage group.Paper chromatography of the fraction hydrolysate demonstrated the presence of glucurone, xylose, arabinose, glucose and galactose.