Characteristic fragment ions from lignin and polysaccharides in ToF–SIMS

Different model compounds for lignin, hemicelluloses and pectins were studied by time-of-flight secondary-ion mass spectrometry (ToF–SIMS). Mass spectra of Klason lignin from normal and compression spruce wood, aspen wood and wheat straw were compared. Spectra of brominated spruce and aspen wood sections showed fragment ions attributed to brominated guaiacyl and syringyl units in lignin at m/z 215, 217, 229 and 231, and m/z 245, 247, 249 and 261, respectively. Spectra of mono-, oligo- and polysaccharides showed fragment ions at m/z 127 and 145 characteristic for hexose units, and ions at m/z 115 and 133 characteristic for pentose units. The same ions were detected in spectra of delignified spruce and aspen wood sections. Labelling of anionic groups by Sr²⁺ ions followed by ToF–SIMS analysis showed that pectins were present at specific locations on the surfaces of spruce and aspen wood sections still after delignification with hydrogen peroxide in acetic acid.     

Ecological evaluation of polymetallic soil quality: the applicability of culture-dependent methods of bacterial communities studying

Purpose

This work aimed to study the effect of long-term polymetallic contamination on the state and parameters of soil bacterial communities, including the abundance of different groups of culturable bacteria and the activity of nitrification.

Materials and methods

Monitoring plots were located in the dry lake and surrounding area, which had been formerly used for the discharge of industrial waste. The soils in the 16 plots were characterized by extremely high levels of heavy metal pollution. This study evaluated the main soil physicochemical properties by various methods, total metal contents by X-ray analysis, mobile metal content by atomic absorption spectrophotometry, the abundance of chosen groups of culturable bacteria by inoculation on solid media, and nitrification activity from ammonium and nitrite oxidation rates.

Results and discussion

High adaptation capacity of microbial communities to long-term pollution was revealed through marked lack of decrease in the abundance of some of the bacterial groups in soils with high contamination levels. Among the bacteria determined by the colony count method, copiotrophic and spore-forming bacteria were the least sensitive to contamination, and actinomycetes were the most sensitive. The high levels of soil pollution with heavy metals had pronounced adverse effects on nitrification activity. The decrease in activity was strongly correlated with pollutant concentrations. The oxidation of nitrite was shown to be more affected by pollution that the oxidation of ammonium.

Conclusions

Some groups and parameters of culturable microorganisms can be used for soil status estimation under pollution conditions even though they are only a small fraction of the microbial community. The most sensitive parameter was the nitrification rate, while the number of actinomycetes was found to be most promising parameter among the groups of bacteria determined by plate counts. The use of sensitive groups of culturable microorganisms for bioindication purposes is a method, which may provide a cheap and sufficiently reliable tool for large-scale soil monitoring studies.

     

Biodegradation of humic substances by microscopic filamentous fungi: chromatographic and spectroscopic proxies

Purpose

The study of interactions between humic substances (HSs) and soil filamentous fungi is the key to understanding the sustainable soil functioning. The present work aims to examine the decomposition of HSs by filamentous dark-pigmented fungus Alternaria alternatа under the laboratory conditions and to determine the effect of easily assimilable organic carbon on this process. Analyzing such polydisperse substances like HSs by a complex integrated methodology makes it possible to explore the data on their decomposition by microorganisms.

Materials and methods

To achieve the aforementioned goals, we used chromatographic and spectroscopic approaches: low-pressure size-exclusion and hydrophobic interaction chromatography accompanied by absorption and fluorescence spectroscopy. To determine the effect cometabolism conditions produced on HS decomposition, two types of carbon substrates were added to the nutrient media: easily assimilable organic carbon (standard 0.3% or reduced 0.03% sucrose content) and hardly assimilable organic carbon (HSs), as well as their combinations. Five HS samples of different organic matter origin have been inspected: potassium humates (HPs) and humic acids (HAs) from coal, peat, and lignosulfonate. Correlation matrix and principal component analysis (PCA) were calculated for comprehensive data analysis.

Results and discussion

Transformations of the investigated HSs under fungal cultivation lead to the increase in the low molecular weight fraction, rise of hydrophilic fraction, enlargement of absorbance ratio A₂₅₀/A₃₆₅, shortening of the emission wavelength of the humic-type fluorescence, and growth in the fluorescence quantum yield measured with excitation at 355 nm. A positive correlation was observed between the accumulation of fungal biomass and the degree of HS decomposition. PCA analysis confirms that the difference in the results of HS decomposition largely depends on the sucrose content and the nature of HSs. We divided all the HS samples into four groups according to the degree of HS decomposition: original HS solutions, HPs altered using fungal cultivation at 0.03% sucrose, HAs after fungal cultivation at 0.03% sucrose, and finally, HSs (both HPs and HAs) after fungal cultivation at 0.3% sucrose.

Conclusions

In the laboratory experiments, we showed that (1) the isolated HAs were more effectively degraded than the parent HPs, and this process was more pronounced at a reduced sucrose content, and (2) the decomposition of stable organic compounds (HSs) was activated by the easily assimilable carbon sources (especially 0.3% sucrose) being present. We assume that it is the easily assimilable organic carbon that most likely triggers the HS degradation working as the priming effect in natural environments.

     

Effect of nanoparticles on crops and soil microbial communities

Purpose

Nanoparticles (NPs) have received increased attention in recent past due to their unique distinct properties. Metal-based NPs are widely used in chemical and allied sector. Most of the research is directed to study the efficiency of NPs in medicine and agriculture. The aim of this review is to explore the possible threats posed by toxicity of various NPs on plants and microbial diversity.

Materials and methods

First, major sources of NPs to the environment were analyzed. The effects of metal-based NPs on the microbiota and plants are presented in this review. The results obtained by the authors during last 12 years of research are used.

Results and discussion

The exposure of soil to nanoparticles causes a decrease in soil microbial biomass and enzymatic activity, which impacts microbial community composition including yeasts, bacteria, fungi, and biological diversity. The effects of NPs on plants result in various types of abnormalities. Nanoparticles can also pose risks to human health.

Conclusions

Increased applications of NPs pose a threat to beneficial microbial communities as well as crops and soils. Thus, it is important to explore whether NPs could compromise crop yield, soil properties, soil organisms, and functional activities of soil.

     

含非洲猪瘟病毒核酸序列病毒样颗粒的研制及其在检测方法中的应用

非洲猪瘟（African swine fever,ASF）是由非洲猪瘟病毒（African swine fever virus,ASFV）引起的烈性传染病,为了保证其检测结果的准确性和可靠性,需要研制试剂盒中使用的阳性标准质控品。本试验旨在研制含ASFV核酸序列的病毒样颗粒,并探究其在检测方法中的应用。首先扩增p72基因的全长片段,利用昆虫杆状病毒系统,包装出含有p72基因的ASF DNA病毒样颗粒。为了进一步验证该病毒样颗粒在应用中的可靠性,本研究将病毒样颗粒与ASF的组织毒及细胞毒同时进行DNA核酸提取,进行实时荧光定量PCR。结果表明,本研究制备的病毒样粒子能很好的取代ASFV在实时荧光定量PCR检测方法中作为阳性质控品,且能对核酸提取过程进行质控,实时荧光定量PCR检测试剂盒中,病毒样粒子的最低包装浓度为10² TCID₅₀。进一步研究发现该病毒样颗粒也适用于普通PCR及LAMP检测方法中,最低浓度分别为10³和10¹ TCID₅₀。本试验结果将为规范ASF检测方法,促进ASF检测方法的转化应用及保证检测结果的准确度和可靠性提供科学依据。     

Strategies and priorities in field collections for ex situ conservation: the case of the Israel Plant Gene Bank

The ex situ collection of the Israel Plant Gene Bank (IGB) aims to encompass the rich local flora and its genetic diversity with an emphasis on crop wild relatives. However, to properly establish a core collection, collection efforts must be prioritized and strategized. We previously classified local plant genetic resources into four priority groups that assisted in strategizing the collection activities. The following years of intensive collection activity yielded over 4200 banked accessions. However, these do not necessarily represent the distribution range of the target species for collection (TSC) and consequently, their genetic diversity. To best cover the latter, the collecting area was divided into botanical districts and the magnitude of the collection was determined according to prioritization group, e.g., a wild relative of an agricultural crop with a vast distribution range should be represented by a larger number of banked accessions than one with a smaller range. Continuous evaluation of specific needs shapes the collection scheme of the IGB to maximize collection efforts, better represent the presumed genetic diversity of TSC, and establish its core collection.     

Effects of vaccination against brucellosis and clostridia on the intake,performance, feeding behavior,blood parameters,and immune responses of dairy heifers calves

The aim of this study was to identify possible effects of different vaccination strategies (concomitantly or not) against brucellosis and clostridia on intake, performance, feeding behavior, blood parameters, and immune responses of dairy heifers calves. Fifty heifers calves were enrolled [38 Gyr (Zebu, Bos taurus indicus) and 12 5/8 Holstein Gyr]. At 120 d of age, animals were randomly distributed among 3 groups: B (n = 18), vaccinated against brucellosis; C (n = 14), vaccinated against clostridia and CB (n = 18), vaccinated concomitantly for both. Rectal and thermographic temperatures were evaluated on days 1, 0, 1, 2, 3, 5, 7,10, 14, and 28 relatives to the vaccination day. Feed and water intake, body weight (BW), and feeding behavior were monitored daily by an electronic feeding system. Blood was sampled on days 0, 3, 7, 14, and 28, relative to the vaccination day for determination of glucose and -hydroxybutyrate (BHBA) concentrations. Blood sampled on day 0 (prevaccination) and on days 28 and 42 were used to evaluate the immune response against Brucella abortus and clostridia. There was an increase in rectal temperature between the first and the third day postvaccination in the 3 groups. The thermography revealed an increase of local temperature for 7 d on groups B and CB. Group C had increased local temperature for a longer period, lasting for up to 14 d. Dry mater intake was reduced for groups B and CB, but no alteration was observed for group C. No alterations regarding initial BW, final BW, average daily weight gain, and feed efficiency were observed. No differences were observed for the 3 vaccination groups for blood parameters throughout the evaluation period. The concomitant vaccination against brucellosis and clostridia led to lower neutralizing antibody titers against epsilon toxin of Clostridium perfringens and botulinum toxin type C of C. botulinum (C > CB > B). When cellular proliferation assay and serological tests to B. abortus were evaluated, no differences were observed between groups B and CB. The present results indicate that the concomitant vaccination against brucellosis and clostridia has no relevant impact on the intake, performance, and feeding behavior of dairy calves. However, the concomitant vaccination of vaccines against these 2 pathogens impacts animal immunity against clostridial infections.     

The multielectron ionization dynamics underlying attosecond strong-field spectroscopies

Subcycle strong-field ionization (SFI) underlies many emerging spectroscopic probes of atomic or molecular attosecond electronic dynamics. Extending methods such as attosecond high harmonic generation spectroscopy to complex polyatomic molecules requires an understanding of multielectronic excitations, already hinted at by theoretical modeling of experiments on atoms, diatomics, and triatomics. Here, we present a direct method which, independent of theory, experimentally probes the participation of multiple electronic continua in the SFI dynamics of polyatomic molecules. We use saturated (n-butane) and unsaturated (1,3-butadiene) linear hydrocarbons to show how subcycle SFI of polyatomics can be directly resolved into its distinct electronic-continuum channels by above-threshold ionization photoelectron spectroscopy. Our approach makes use of photoelectron-photofragment coincidences, suiting broad classes of polyatomic molecules.