Chemical Studies on Ninhydrin-Positive Compounds in Cured Tobacco Leaves

A new amino acid, 2-pyrrolidine acetic acid and 1-pipecolic acid were isolated from cured tobacco leaves. The former structure was confirmed by comparison with synthetic compound.     

Estimation of Standing Stock and Decomposition Rates of Labile Organic Matter in Waters of Novorossiisk Bay,Black Sea

The annual dynamics of the decomposition rate, standing stock, and residence time of labile organic matter as an index of full self-purification were investigated in Novorossiisk Bay, Black Sea. The results are suggestive of fairly effective processes of biological self-purification in polluted waters of the bay. The decomposition rate was highest (0.3–0.7 mgO₂/l per day) during the summer, and it decreased by 4–8 times in winter. The residence time of labile organic matter was 97–104 days in winter and 8–11 days in summer. Oxygen consumption rates measured in different areas of the bay conformed to their trophic status and were not above the normal level for summer.     

Rapid Quantitative Method for Salmonella Detection in Polluted Waters

A procedure has been developed for the enumeration of salmonellae in polluted waters using several modifications of existing techniques. Confirmation of salmonellae is achieved within 48 hr. This procedure includes selective enrichment in m-Tetrathionate Broth (22 +/- 1 hr), plating on Brilliant Green Sulfa Agar (20 +/- 1 hr), and confirmation by flagellar (H) agglutination of the growth in a mannosecontaining medium (6 +/- 1 hr). An incubation temperature of 41.5 C was used throughout this procedure. Dilution to extinction techniques (most probable number) were employed to enumerate salmonellae. Large sample volumes were concentrated through the use of membrane filters. This technique proved to be rapid and reliable for the enumeration of salmonellae in water, waste water, and waste-water sludges.     

Autumn Retranslocation of Heavy Metals from Leaves of Woody Plants in Forest Ecosystems

Biology Bulletin - This paper examines the autumn retranslocation of heavy metals (HMs), namely Cu, Zn, and Cd, from the photosynthetic organs of woody plants. This study was carried out in the...     

Estimation of Chlorophyll in Tobacco Leaves by Direct Photometry

A simple portable instrument utilizing a cadmium sulphide light-dependentresistor in a bridge circuit, and its use in the in vivo estimationof total chlorophyll content of tobacco leaves, are described.The method has wide applicability in plant physiological andnutritional research, and in agriculture. The relationship betweeninstrument readout and chlorophyll content (calibration curve)was nearly parabolic and was determined largely by the light-scatteringproperties of the leaf. The effects of some environmental andplant parameters on this relationship and on the precision ofthe estimation were analysed. The importance of sampling procedurewas emphasized by a marked heterogeneity of chlorophyll distributionfound within leaves of all ages. A scattered-transmission spectrophotometerwas found to give the same type of calibration curve, and wasused to demonstrate that the ‘reference wavelength’correction used by previous authors has no effect on the shapeof the curve or the precision of the method.     

Salinity Constraints on Subsurface Archaeal Diversity and Methanogenesis in Sedimentary Rock Rich in Organic Matter

The diversity of microorganisms active within sedimentary rocks provides important controls on the geochemistry of many subsurface environments. In particular, biodegradation of organic matter in sedimentary rocks contributes to the biogeochemical cycling of carbon and other elements and strongly impacts the recovery and quality of fossil fuel resources. In this study, archaeal diversity was investigated along a salinity gradient spanning 8 to 3,490 mM Cl⁻ in a subsurface shale rich in CH₄ derived from biodegradation of sedimentary hydrocarbons. Shale pore waters collected from wells in the main CH₄-producing zone lacked electron acceptors such as O₂, NO₃⁻, Fe³⁺, or SO₄²⁻. Acetate was detected only in high-salinity waters, suggesting that acetoclastic methanogenesis is inhibited at Cl⁻ concentrations above ~1,000 mM. Most-probable-number series revealed differences in methanogen substrate utilization (acetate, trimethylamine, or H₂/CO₂) associated with chlorinity. The greatest methane production in enrichment cultures was observed for incubations with salinity at or close to the native pore water salinity of the inoculum. Restriction fragment length polymorphism analyses of archaeal 16S rRNA genes from seven wells indicated that there were links between archaeal communities and pore water salinity. Archaeal clone libraries constructed from sequences from 16S rRNA genes isolated from two wells revealed phylotypes similar to a halophilic methylotrophic Methanohalophilus species and a hydrogenotrophic Methanoplanus species at high salinity and a single phylotype closely related to Methanocorpusculum bavaricum at low salinity. These results show that several distinct communities of methanogens persist in this subsurface, CH₄-producing environment and that each community is adapted to particular conditions of salinity and preferential substrate use and each community induces distinct geochemical signatures in shale formation waters.     

Quantitative Estimation of Phloem Regeneration in Coleus Internodes

Phloem regeneration in Coleus internodes, earlier wounded so that one or more phloem bundles were severed, is estimated quantitatively by microscopic examination of permanent slides prepared in the following way: The wounded internode is removed from the plant after a given regeneration period, is fixed in Craf III for 24 hr and is transferred to 85% lactic acid for 12-24 hr. While still in lactic acid, a “strip”, which is composed of the phloem and all tissues peripheral to it in the internode, is peeled from the internode, leaving only the xylem-pith cylinder. The strip is stained for 6-12 hr in 0.1% aniline blue in 85% lactic acid, then is transferred to 60% alcohol containing 0.5% HCI. While in the latter solution, the epidermis, scar tissue, and most of the cortical tissue is carefully dissected from the strip while it is observed in a dissecting microscope. The strip is restained for an hour or more and is passed through two 5-10 min changes each of acidified 60% alcohol, absolute alcohol, and xylene, and is then mounted on a glass slide in damar-xylene. Counts of regenerated, interfascicular phloem strands, governed by a counting convention, which were shown to bear a fairly constant relationship to the actual number of regenerated sieve tube members, are made while examining under low and high power magnifications. This method is presently being used to study the physiology of phloem differentiation and its regulation in Coleus.     

Quantitative Microbial Risk Assessment of Pathogenic Vibrios in Marine Recreational Waters of Southern California

This study investigated the occurrence of three types of vibrios in Southern California recreational beach waters during the peak marine bathing season in 2007. Over 160 water samples were concentrated and enriched for the detection of vibrios. Four sets of PCR primers, specific for Vibrio cholerae, V. parahaemolyticus, and V. vulnificus species and the V. parahaemolyticus toxin gene, respectively, were used for the amplification of bacterial genomic DNA. Of 66 samples from Doheny State Beach, CA, 40.1% were positive for V. cholerae and 27.3% were positive for V. parahaemolyticus, and 1 sample (1.5%) was positive for the V. parahaemolyticus toxin gene. Of the 96 samples from Avalon Harbor, CA, 18.7% were positive for V. cholerae, 69.8% were positive for V. parahaemolyticus, and 5.2% were positive for the V. parahaemolyticus toxin gene. The detection of the V. cholerae genetic marker was significantly more frequent at Doheny State Beach, while the detection of the V. parahaemolyticus genetic marker was significantly more frequent at Avalon Harbor. A probability-of-illness model for V. parahaemolyticus was applied to the data. The risk for bathers exposed to recreational waters at two beaches was evaluated through Monte Carlo simulation techniques. The results suggest that the microbial risk from vibrios during beach recreation was below the illness benchmark set by the U.S. EPA. However, the risk varied with location and the type of water recreation activities. Surfers and children were exposed to a higher risk of vibrio diseases. Microbial risk assessment can serve as a useful tool for the management of risk related to opportunistic marine pathogens.     

Comparison of Concentration Methods for Quantitative Detection of Sewage-Associated Viral Markers in Environmental Waters

Pathogenic human viruses cause over half of gastroenteritis cases associated with recreational water use worldwide. They are relatively difficult to concentrate from environmental waters due to typically low concentrations and their small size. Although rapid enumeration of viruses by quantitative PCR (qPCR) has the potential to greatly improve water quality analysis and risk assessment, the upstream steps of capturing and recovering viruses from environmental water sources along with removing PCR inhibitors from extracted nucleic acids remain formidable barriers to routine use. Here, we compared the efficiency of virus recovery for three rapid methods of concentrating two microbial source tracking (MST) viral markers human adenoviruses (HAdVs) and polyomaviruses (HPyVs) from one liter tap water and river water samples on HA membranes (90 mm in diameter). Samples were spiked with raw sewage, and viral adsorption to membranes was promoted by acidification (method A) or addition of MgCl₂ (methods B and C). Viral nucleic acid was extracted directly from membranes (method A), or viruses were eluted with NaOH and concentrated by centrifugal ultrafiltration (methods B and C). No inhibition of qPCR was observed for samples processed by method A, but inhibition occurred in river samples processed by B and C. Recovery efficiencies of HAdVs and HPyVs were ∼10-fold greater for method A (31 to 78%) than for methods B and C (2.4 to 12%). Further analysis of membranes from method B revealed that the majority of viruses were not eluted from the membrane, resulting in poor recovery. The modification of the originally published method A to include a larger diameter membrane and a nucleic acid extraction kit that could accommodate the membrane resulted in a rapid virus concentration method with good recovery and lack of inhibitory compounds. The frequently used strategy of viral absorption with added cations (Mg²⁺) and elution with acid were inefficient and more prone to inhibition, and will result in underestimation of the prevalence and concentrations of HAdVs and HPyVs markers in environmental waters.     

Quantitative Estimation of Ipomeamarone by Chromatostrip Technique

Method of analysing a microquantity of ipomcamarone was established by silica gel chromatostrip technique for its separation and the subsequent colorimetric determination of the 2.4-dinitrophenylhydrazone in alkaline condition. Preliminary analysis of ipomeamarone based on this method was carried out for sweet potato roots infected by the black rot during ninety six hours period.     

北京市五大水系水体浮游细菌的数量特征研究

为掌握水域浮游细菌数量分布特征及其变化情况,采用荧光显微镜细菌计数法（AODC）于2016年6月至2018年9月研究了北京市五大水系浮游细菌的数量特征。结果表明,各水系浮游细菌密度分别为潮白河水系（0.24～28.46）×104 cell/mL,大清河水系（1.34～64.00）×10⁴ cell/mL,永定河水系（0.17～6.77）×10⁴ cell/mL,北运河水系（0.24～64.00）×10⁴ cell/mL,蓟运河水系（0.80～112.00）×10⁴ cell/mL。SPSS相关分析表明,各水系浮游细菌密度与水体理化因子间的相关性存在明显差异,大清河水系细菌密度与TN（P<0.05）呈显著正相关,与TP（P<0.01）和ADP(P<0.01)呈极显著正相关;永定河水系细菌密度与TAN（P<0.05）和TP(P<0.05)呈显著正相关,与ADP（P<0.01）呈极显著正相关;蓟运河水系细菌密度与Chl-a（P<0.05）呈显著正相关;潮白河水系及北运河水系细菌密度则与各理化因子均无显著相关性。从浮游细菌数量来看,各水系水质均较好,其中永定河水系水质最优。     

Quantitative Detection of Escherichia coli O157 in Surface Waters by Using Immunomagnetic Electrochemiluminescence

A protocol for the quantitative detection of Escherichia coli O157 in raw and concentrated surface waters using immunomagnetic electrochemiluminescence (IM-ECL) was developed and optimized. Three antibody sandwich formats were tested: commercial anti-O157:H7 IM beads, IM beads made in-house with a polyclonal anti-O157:H7 immunoglobulin G (IgG), or IM beads made in-house with a monoclonal anti-O157:H7 IgG coupled with a polyclonal anti-O157:H7 IgG to which an electrochemiluminescent label (TAG) was attached. The monoclonal IM bead-polyclonal TAG format was chosen for optimization because it gave lower background levels and linear regression slopes of ca. 1.0, indicative of a constant ECL signal per cell. The dynamic range was ca. 10¹ to 10⁵ cells ml⁻¹ in phosphate-buffered saline and in raw water samples. The monoclonal IM beads selectively captured E. coli O157 cells in the presence of ca. 10⁸ cells of a non-O157 strain of E. coli ml⁻¹. Background ECL signals from concentrated (100-fold) water samples were substantially higher and more variable than raw water samples. The background signal was partially eliminated by the addition of polyvinylpolypyrrolidone. Successive cell capture incubations, termed sequential bead capture (SBC), were optimized for establishing baseline ECL values for individual water samples. The linear dynamic range with SBC was ca. 10² to 10⁵ E. coli O157 cells ml of concentrated water⁻¹. To validate the protocol, 10-liter surface water samples were spiked with ca. 5,000 E. coli O157 (Odwalla) cells and concentrated by vortex filtration, and 1- or 3-ml aliquots were analyzed by IM-ECL. Differential ECL signals (SBC) from 1- and 3-ml samples were statistically significant and were generally consistent with standard curves for these cell concentrations. Enrichments were conducted with aliquots of spiked raw water and concentrated water using EC broth and minimal lactose broth (MLB). All tubes with concentrated water became turbid and gave a positive ECL response for E. coli O157 (>10,000 ECL units); MLB gave a somewhat higher detection rate with spiked raw water. The potential sensitivity of the IM-ECL assay is ca. 25 E. coli O157 cells ml of raw water⁻¹, 25 cells 100 ml of 100-fold concentrated water⁻¹, or 1 to 2 viable cells liter⁻¹ with concentration and enrichment. The IM-ECL assay appears suitable for routine analysis and screening of water samples.