Implantation of a novel insertable cardiac monitor: preliminary multicenter experience in Europe

BACKGROUND

The LUX-Dx™ is a novel insertable cardiac monitor (ICM) introduced into the European market since October 2022.

PURPOSE

The aim of this investigation was to provide a comprehensive description of the ICM implantation experience in Europe during its initial year of commercial use.

METHODS

The system comprises an incision tool and a single-piece insertion tool pre-loaded with the small ICM. The implantation procedure involves incision, creation of a device pocket, insertion of the ICM, verification of sensing, and incision closure. Patients receive a mobile device with a preloaded App, connecting to their ICM and transmitting data to the management system. Data collected at European centers were analyzed at the time of implantation and before patient discharge.

RESULTS

A total of 368 implantation procedures were conducted across 23 centers. Syncope (235, 64%) and cryptogenic stroke (34, 9%) were the most frequent indications for ICM. Most procedures (338, 92%) were performed in electrophysiology laboratories. All ICMs were successfully implanted in the left parasternal region, oriented at 45° in 323 (88%) patients. Repositioning was necessary after sensing verification in 9 (2%) patients. No procedural complications were reported, with a median time from skin incision to suture of 4 min (25th-75th percentiles 2-7). At implantation, the mean R-wave amplitude was 0.39 ± 0.30 mV and the P-wave visibility was 91 ± 20%. Sensing parameters remained stable until pre-discharge and were not influenced by patient characteristics or indications. Procedural times were fast, exhibited consistency across patient groups, and improved after an initial experience with the system. Operator Operator feedback on the system was positive. Patients reported very good ease of use of the App and low levels of discomfort after implantation.

CONCLUSIONS

LUX-Dx™ implantation appears efficient and straightforward, with favorable post-implantation sensing values and associated with positive feedback from operators and patients.

Visuomotor control in mice and primates

We conduct a comparative evaluation of the visual systems from the retina to the muscles of the mouse and the macaque monkey noting the differences and similarities between these two species. The topics covered include (1) visual-field overlap, (2) visual spatial resolution, (3) V1 cortical point-image [i.e., V1 tissue dedicated to analyzing a unit receptive field], (4) object versus motion encoding, (5) oculomotor range, (6) eye, head, and body movement coordination, and (7) neocortical and cerebellar function. We also discuss blindsight in rodents and primates which provides insights on how the neocortex mediates conscious vision in these species. This review is timely because the field of visuomotor neurophysiology is expanding beyond the macaque monkey to include the mouse; there is therefore a need for a comparative analysis between these two species on how the brain generates visuomotor responses.

A comprehensive assessment of potential hazard caused by organic compounds in biochar for agricultural use

Great attention has been paid to using biochar as soil conditioner and bio-accumulator. Nevertheless, biochar application in agriculture might cause a potential hazard to ecosystems, considering that toxic organic pollutants present in biochar may enter the environment. European Biochar Certificate (EBC) set certain criteria for biochar production. Achieving the EBC established values of the molar ratio of H/C_org <0.7 and O/C_org <0.4, does not ensure that biochar will not cause phytotoxicity. The results of root growth inhibition of Sinapis alba were in the range of 9% (eucalyptus wood biochar) to 82% (maize biochar). Phytotoxicity of biochar was possibly caused by the presence of water-soluble organic compounds. In total, 62 organic compounds were identified in the leachate from noncertified biochar and 35 organic compounds in the leachate from certified biochar. Biochar safety, in terms of the presence of organic compounds, can be recognised by the evaluation of the ratio of organic carbon (OC) and elemental carbon (EC). Biochar with the highest phytotoxicity showed the ratio between OC/EC > 0.1, inhibition of Sinapis alba <30% was observed with OC/EC < 0.02. To achieve Sinapis alba inhibition <20%, these parameters should be met: volatile matter (VM) <30%; concentration of OC < 4%; aromaticity ratio AL/AR < 0.35.

Biochars from olive mill waste have contrasting effects on plants, fungi and phytoparasitic nematodes

Olive mill waste (OMW), a byproduct from the extraction of olive oil, causes serious environmental problems for its disposal, and extensive efforts have been made to find cost-effective solutions for its management. Biochars produced from OMW were applied as soil amendment and found in many cases to successfully increase plant productivity and suppress diseases. This work aims to characterize biochars obtained by pyrolysis of OMW at 300 °C to 1000 °C using ¹³C NMR spectroscopy, LC-ESI-Q-TOF-MS and SEM (Scanning Electron Microscopy). Chemical characterization revealed that biochar composition varied according to the increase of pyrolysis temperature (PT). Thermal treated materials showed a progressive reduction of alkyl C fractions coupled to the enrichment in aromatic C products. In addition, numerous compounds present in the organic feedstock (fatty acids, phenolic compounds, triterpene acids) reduced (PT = 300 °C) or completely disappeared (PT ≥ 500 °C) in biochars as compared to untreated OMW. PT also affected surface morphology of biochars by increasing porosity and heterogeneity of pore size. The effects of biochars extracts on the growth of different organisms (two plants, one nematode and four fungal species) were also evaluated. When tested on different living organisms, biochars and OMW showed opposite effects. The root growth of Lepidium sativum and Brassica rapa, as well as the survival of the nematode Meloidogyne incognita, were inhibited by the untreated material or biochar produced at 300 °C, but toxicity decreased at higher PTs. Conversely, growth of Aspergillus, Fusarium, Rhizoctonia and Trichoderma fungi was stimulated by organic feedstock, while being inhibited by thermally treated biochars. Our findings showed a pattern of association between specific biochar chemical traits and its biological effects that, once mechanistically explained and tested in field conditions, may lead to effective applications in agriculture.

Polyketide synthases of Diaporthe helianthi and involvement of DhPKS1 in virulence on sunflower

BACKGROUND

The early phases of Diaporthe helianthi pathogenesis on sunflower are characterized by the production of phytotoxins that may play a role in host colonisation. In previous studies, phytotoxins of a polyketidic nature were isolated and purified from culture filtrates of virulent strains of D. helianthi isolated from sunflower. A highly aggressive isolate (7/96) from France contained a gene fragment of a putative nonaketide synthase (lovB) which was conserved in a virulent D. helianthi population.

RESULTS

In order to investigate the role of polyketide synthases in D. helianthi 7/96, a draft genome of this isolate was examined. We were able to find and phylogenetically analyse 40 genes putatively coding for polyketide synthases (PKSs). Analysis of their domains revealed that most PKS genes of D. helianthi are reducing PKSs, whereas only eight lacked reducing domains. Most of the identified PKSs have orthologs shown to be virulence factors or genetic determinants for toxin production in other pathogenic fungi. One of the genes (DhPKS1) corresponded to the previously cloned D. helianthi lovB gene fragment and clustered with a nonribosomal peptide synthetase (NRPS) -PKS hybrid/lovastatin nonaketide like A. nidulans LovB. We used DhPKS1 as a case study and carried out its disruption through Agrobacterium-mediated transformation in the isolate 7/96. D. helianthi DhPKS1 deleted mutants were less virulent to sunflower compared to the wild type, indicating a role for this gene in the pathogenesis of the fungus.

CONCLUSION

The PKS sequences analysed and reported here constitute a new genomic resource that will be useful for further research on the biology, ecology and evolution of D. helianthi and generally of fungal plant pathogens.

Biochar As Plant Growth Promoter: Better Off Alone or Mixed with Organic Amendments?

Biochar is nowadays largely used as a soil amendment and is commercialized worldwide. However, in temperate agro-ecosystems the beneficial effect of biochar on crop productivity is limited, with several studies reporting negative crop responses. In this work, we studied the effect of 10 biochar and 9 not pyrogenic organic amendments (NPOA), using pure and in all possible combinations on lettuce growth (Lactuca sativa). Organic materials were characterized by ¹³C-CPMAS NMR spectroscopy and elemental analysis (pH, EC, C, N, C/N and H/C ratios). Pure biochars and NPOAs have variable effects, ranging from inhibition to strong stimulation on lettuce growth. For NPOAs, major inhibitory effects were found with N poor materials characterized by high C/N and H/C ratio. Among pure biochars, instead, those having a low H/C ratio seem to be the best for promoting plant growth. When biochars and organic amendments were mixed, non-additive interactions, either synergistic or antagonistic, were prevalent. However, the mixture effect on plant growth was mainly dependent on the chemical quality of NPOAs, while biochar chemistry played a secondary role. Synergisms were prevalent when N rich and lignin poor materials were mixed with biochar. On the contrary, antagonistic interactions occurred when leaf litter or woody materials were mixed with biochar. Further research is needed to identify the mechanisms behind the observed non-additive effects and to develop biochar-organic amendment combinations that maximize plant productivity in different agricultural systems.

Litter chemistry explains contrasting feeding preferences of bacteria, fungi, and higher plants

Litter decomposition provides a continuous flow of organic carbon and nutrients that affects plant development and the structure of decomposer communities. Aim of this study was to distinguish the feeding preferences of microbes and plants in relation to litter chemistry. We characterized 36 litter types by 13C-CPMAS NMR spectroscopy and tested these materials on 6 bacteria, 6 fungi, and 14 target plants. Undecomposed litter acted as a carbon source for most of the saprophytic microbes, although with a large variability across litter types, severely inhibiting root growth. An opposite response was found for aged litter that largely inhibited microbial growth, but had neutral or stimulatory effects on root proliferation. 13C-CPMAS NMR revealed that restricted resonance intervals within the alkyl C, methoxyl C, O-alkyl C and di-O-alkyl C spectral regions are crucial for understanding litter effects. Root growth, in contrast to microbes, was negatively affected by labile C sources but positively associated with signals related to plant tissue lignification. Our study showed that plant litter has specific and contrasting effects on bacteria, fungi and higher plants, highlighting that, in order to understand the effects of plant detritus on ecosystem structure and functionality, different microbial food web components should be simultaneously investigated.

Draft whole-genome sequence of the Diaporthe helianthi 7/96 strain, causal agent of sunflower stem canker

Diaporthe helianthi is a fungus pathogenic to sunflower. Virulent strains of this fungus cause stem canker with important yield losses and reduction of oil content. Here we present the first draft whole-genome sequence of the highly virulent isolate D. helianthi strain 7/96, thus providing a useful platform for future research on stem canker of sunflower and fungal genomics. The genome sequence of the D. helianthi isolate 7/96 was deposited at DDBJ/ENA/GenBank under the accession number MAVT00000000 (BioProject PRJNA327798).

Climate, Soil Management, and Cultivar Affect Fusarium Head Blight Incidence and Deoxynivalenol Accumulation in Durum Wheat of Southern Italy

Fusarium head blight (FHB) is a multifaceted disease caused by some species of Fusarium spp. A huge production of mycotoxins, mostly trichothecenes, often accompanied this disease. Amongst these toxic compounds, deoxynivalenol (DON) and its derivatives represent a major issue for human as well as for animal health and farming. Common and durum wheat are amongst the hosts of trichothecene-producing Fusaria. Differences in susceptibility to fungal infection and toxin accumulation occur in wheat cultivars. Recently, increasing incidence and severity of Fusarium infection and a higher DON accumulation in durum wheat were observed in Italy, especially in Northern regions. In this study, we analyzed wheat yield, technological parameters, the incidence of Fusarium infection and DON content in kernel samples of durum wheat coming from three locations of Southern Italy with different climatic conditions and grown during two seasons, with two methods of cultivation. Four different durum wheat cultivars prevalently cultivated in Southern Italian areas were chosen for this study. Our analysis showed the effects of environment and cultivar types on wheat productivity and key technological parameters for the quality level of the end-product, namely pasta. Notably, although a low rate of mycotoxin contamination in all study sites was assessed, an inverse relation emerged between fungal infection/DON production and durum wheat yield. Further, our study pinpoints the importance of environment conditions on several quality traits of durum wheat grown under Mediterranean climate. The environmental conditions at local level (microscale) and soil management practices may drive FHB outbreak and mycotoxin contamination even in growing area suitable for cropping this wheat species.

Sphaceloma coryli: A Reemerging Pathogen Causing Heavy Losses on Hazelnut in Southern Italy

In 2013 to 2014, a disease causing severe crop losses was observed in several growing areas of the Campania region in southern Italy. Disease symptoms consisted of necrotic spots on leaves, bracts, and shells along with vein necrosis. Nuts were necrotic or aborted and symptomatic fruit dropped prematurely. A fungus was consistently isolated from symptomatic tissues and morphologically identified as Sphaceloma coryli. The fungus was first reported in France and Italy (Campania) over 30 years ago and was not subsequently documented until 2006 in the Latium region of Italy. When artificially inoculated on healthy hazelnut plants, disease symptoms were reproduced. The teleomorph of S. coryli was recorded for the first time on overwintering tissues of hazelnut trees. It was also induced in vitro. The morphology of asci and ascospores together with phylogenetic analysis based on internal transcribed spacer sequences indicated that the teleomorph is an undescribed species within the genus Elsinoë for which the name of Elsinoë coryli is proposed. Optimum temperatures for ascospore and conidium germination and mycelium growth were determined in vitro. The inhibition effect of some commercial fungicides on S. coryli was also evaluated in vitro.

Genetic variability and evolutionary diversification of membrane ABC transporters in plants

BACKGROUND

ATP-binding cassette proteins have been recognized as playing a crucial role in the regulation of growth and resistance processes in all kingdoms of life. They have been deeply studied in vertebrates because of their role in drug resistance, but much less is known about ABC superfamily functions in plants.

RESULTS

Recently released plant genome sequences allowed us to identify 803 ABC transporters in four vascular plants (Oryza. sativa, Solanum lycopersicum, Solanum tuberosum and Vitis vinifera) and 76 transporters in the green alga Volvox carteri, by comparing them with those reannotated in Arabidopsis thaliana and the yeast Saccharomyces cerevisiae. Retrieved proteins have been phylogenetically analysed to infer orthologous relationships. Most orthologous relationships in the A, D, E and F subfamilies were found, and interesting expansions within the ABCG subfamily were observed and discussed. A high level of purifying selection is acting in the five ABC subfamilies A, B, C, D and E. However, evolutionary rates of recent duplicate genes could influence vascular plant genome diversification. The transcription profiles of ABC genes within tomato organs revealed a broad functional role for some transporters and a more specific activity for others, suggesting the presence of key ABC regulators in tomato.

CONCLUSIONS

The findings achieved in this work could contribute to address several biological questions concerning the evolution of the relationship between genomes of different species. Plant ABC protein inventories obtained could be a valuable tool both for basic and applied studies. Indeed, interpolation of the putative role of gene functions can accelerate the discovering of new ABC superfamily members.

Multiple roles and effects of a novel Trichoderma hydrophobin

Fungi belonging to the genus Trichoderma are among the most active and ecologically successful microbes found in natural environments, because they are able to use a variety of substrates and affect the growth of other microbes and virtually any plant species. We isolated and characterized a novel type II hydrophobin secreted by the biocontrol strain MK1 of Trichoderma longibrachiatum. The corresponding gene (Hytlo1) has a multiple role in the Trichoderma-plant-pathogen three-way interaction, while the purified protein displayed a direct antifungal as well as a microbe-associated molecular pattern and a plant growth promotion (PGP) activity. Leaf infiltration with the hydrophobin systemically increased resistance to pathogens and activated defense-related responses involving reactive oxygen species, superoxide dismutase, oxylipin, phytoalexin, and pathogenesis-related protein formation or activity. The hydrophobin was found to enhance development of a variety of plants when applied at very low doses. It particularly stimulated root formation and growth, as demonstrated also by transient expression of the encoding gene in tobacco and tomato. Targeted knock-out of Hytlo1 significantly reduced both antagonistic and PGP effect of the wild-type strain. We conclude that this protein represents a clear example of a molecular factor developed by Trichoderma spp. to establish a mutually beneficial interaction with the colonized plant.

A role for intracellular zinc in glioma alteration of neuronal chloride equilibrium

Glioma patients commonly suffer from epileptic seizures. However, the mechanisms of glioma-associated epilepsy are far to be completely understood. Using glioma-neurons co-cultures, we found that tumor cells are able to deeply influence neuronal chloride homeostasis, by depolarizing the reversal potential of γ-aminobutyric acid (GABA)-evoked currents (EGABA). EGABA depolarizing shift is due to zinc-dependent reduction of neuronal KCC2 activity and requires glutamate release from glioma cells. Consistently, intracellular zinc loading rapidly depolarizes EGABA in mouse hippocampal neurons, through the Src/Trk pathway and this effect is promptly reverted upon zinc chelation. This study provides a possible molecular mechanism linking glioma invasion to excitation/inhibition imbalance and epileptic seizures, through the zinc-mediated disruption of neuronal chloride homeostasis.

Evaluating the risk of ovarian cancer before surgery using the ADNEX model to differentiate between benign, borderline, early and advanced stage invasive, and secondary metastatic tumours: prospective multicentre diagnostic study

OBJECTIVES

To develop a risk prediction model to preoperatively discriminate between benign, borderline, stage I invasive, stage II-IV invasive, and secondary metastatic ovarian tumours.

DESIGN

Observational diagnostic study using prospectively collected clinical and ultrasound data.

SETTING

24 ultrasound centres in 10 countries.

PARTICIPANTS

Women with an ovarian (including para-ovarian and tubal) mass and who underwent a standardised ultrasound examination before surgery. The model was developed on 3506 patients recruited between 1999 and 2007, temporally validated on 2403 patients recruited between 2009 and 2012, and then updated on all 5909 patients.

MAIN OUTCOME MEASURES

Histological classification and surgical staging of the mass.

RESULTS

The Assessment of Different NEoplasias in the adneXa (ADNEX) model contains three clinical and six ultrasound predictors: age, serum CA-125 level, type of centre (oncology centres v other hospitals), maximum diameter of lesion, proportion of solid tissue, more than 10 cyst locules, number of papillary projections, acoustic shadows, and ascites. The area under the receiver operating characteristic curve (AUC) for the classic discrimination between benign and malignant tumours was 0.94 (0.93 to 0.95) on temporal validation. The AUC was 0.85 for benign versus borderline, 0.92 for benign versus stage I cancer, 0.99 for benign versus stage II-IV cancer, and 0.95 for benign versus secondary metastatic. AUCs between malignant subtypes varied between 0.71 and 0.95, with an AUC of 0.75 for borderline versus stage I cancer and 0.82 for stage II-IV versus secondary metastatic. Calibration curves showed that the estimated risks were accurate.

CONCLUSIONS

The ADNEX model discriminates well between benign and malignant tumours and offers fair to excellent discrimination between four types of ovarian malignancy. The use of ADNEX has the potential to improve triage and management decisions and so reduce morbidity and mortality associated with adnexal pathology.

Interspecific variability of class II hydrophobin GEO1 in the genus Geosmithia

The genus Geosmithia Pitt (Ascomycota: Hypocreales) comprises cosmopolite fungi living in the galleries built by phloeophagous insects. Following the characterization in Geosmithia species 5 of the class II hydrophobin GEO1 and of the corresponding gene, the presence of the geo1 gene was investigated in 26 strains derived from different host plants and geographic locations and representing the whole phylogenetic diversity of the genus. The geo1 gene was detected in all the species tested where it maintained the general organization shown in Geosmithia species 5, comprising three exons and two introns. Size variations were found in both introns and in the first exon, the latter being due to the presence of an intragenic tandem repeat sequence corresponding to a stretch of glycine residues in the deduced proteins. At the amino acid level the deduced proteins had 44.6 % identity and no major differences in the biochemical parameters (pI, GRAVY index, hydropathy plots) were found. GEO1 release in the fungal culture medium was also assessed by turbidimetric assay and SDS-PAGE, and showed high variability between species. The phylogeny based on the geo1 sequences did not correspond to that generated from a neutral marker (ITS rDNA), suggesting that sequence similarities could be influenced by other factors than phylogenetic relatedness, such as the intimacy of the symbiosis with insect vectors. The hypothesis of a strong selection pressure on the geo1 gene was sustained by the low values (<1) of non synonymous to synonymous nucleotide substitutions ratios (Ka/Ks), which suggest that purifying selection might act on this gene. These results are compatible with either a birth-and-death evolution scenario or horizontal transfer of the gene between Geosmithia species.

Identification and characterization of GEO1, a new class II hydrophobin from Geosmithia spp

In the present paper we describe a new noncatalytic protein belonging to the hydrophobin family, designated GEO1, purified from the culture filtrate of Geosmithia pallida (Ascomycota: Hypocreales), and the corresponding gene sequence. In the fungal genome, GEO1 was encoded by a single-copy gene with a 450 bp open reading frame interrupted by 2 small introns whose primary translation product was 109 amino acids long and included a 23 amino acids signal peptide. The mature protein had a molecular mass of 8111.75 Da and a theoretical pI of 4.33. The deduced amino acid sequence showed similarity to class II hydrophobins and contained 8 conserved cysteine residues, present in all hydrophobins isolated so far. Biochemical properties, such as foam-forming ability and trapezoid-like shape of a GEO1 drop, also resembled the typical features of the class II hydrophobins. Expression of the geo1 gene was assessed after 2, 4, 7, 9, and 11 days of culture and showed that the geo1 transcript appeared after 7 days and increased up to 11 days.

Antifungal saponins from bulbs of garlic, Allium sativum L. var. Voghiera

A bioassay-guided phytochemical analysis of the polar extract from the bulbs of garlic, Allium sativum L., var. Voghiera, typical of Voghiera, Ferrara (Italy), allowed the isolation of ten furostanol saponins; voghieroside A1/A2 and voghieroside B1/B2, based on the rare agapanthagenin aglycone; voghieroside C1/C2, based on agigenin aglycone; and voghieroside D1/D2 and E1/E2, based on gitogenin aglycone. In addition, we found two known spirostanol saponins, agigenin 3-O-trisaccharide and gitogenin 3-O-tetrasaccharide. The chemical structures of the isolated compounds were established through a combination of extensive nuclear magnetic resonance, mass spectrometry and chemical analyses. High concentrations of two eugenol diglycosides were also found for the first time in Allium spp. The isolated compounds were evaluated for their antimicrobial activity towards two fungal species, the air-borne pathogen Botrytis cinerea and the antagonistic fungus Trichoderma harzianum.

Antifungal saponins from bulbs of white onion, Allium cepa L

Three saponins, named ceposide A, ceposide B, and ceposide C were isolated from the bulbs of white onion, Allium cepa L. Elucidation of their structure was carried out by comprehensive spectroscopic analyses, including 2D NMR spectroscopy and mass spectrometry, and chemical evidences. The structures of the compounds were identified as (25R)-furost-5(6)-en-1β,3β,22α,26-tetraol 1-O-β-D-xylopyranosyl 26-O-α-D-rhamnoyranosyl-(1→2)-O-β-D-galactopyranoside (ceposide A), (25R)-furost-5(6)-en-1β,3β,22α,26-tetraol 1-O-β-D-xylopyranosyl 26-O-α-D-rhamnoyranosyl-(1→2)-O-β-D-glucopyranoside (ceposide B), and (25R)-furost-5(6)-en-1β,3β,22α,26-tetraol 1-O-β-D-galactopyranosyl 26-O-α-D-rhamnoyranosyl-(1→2)-O-β-D-galactopyranoside (ceposide C). The isolated compounds, alone and in combinations, were evaluated for their antimicrobial activity on ten fungal species. Antifungal activity of all three saponins increased with their concentration and varied with the following rank: ceposide B>ceposide A-ceposide C. We found a significant synergism in the antifungal activity of the three ceposides against Botrytis cinerea and Trichoderma atroviride, because growth of these fungi was strongly inhibited when the three saponins were applied in combination. In contrast, Fusarium oxysporum f. sp. lycopersici, Sclerotium cepivorum and Rhizoctonia solani were very little affected by saponins.

Four potato (Solanum tuberosum) ABCG transporters and their expression in response to abiotic factors and Phytophthora infestans infection

Pleiotropic drug resistant (PDR/ABCG) genes are involved in plant response to biotic and abiotic stresses. In this work, we cloned, from Solanum tuberosum, four PDR/ABCG transporter genes named StPDR1, StPDR2, StPDR3 and StPDR4, which were differentially expressed in plant tissues and cell cultures. A number of different chemically unrelated compounds were found to regulate the transcript levels of the four genes in cultured cells. In particular, StPDR2 was highly up-regulated in the presence of Botrytis cinerea cell walls, NaCl, 2,4-dichlorophenol, sclareol and α-solanin and biological compounds. The expression of the genes was also investigated by real time RT-PCR during infection by Phytophthora infestans. StPDR1 and StPDR2 were up-regulated about 13- and 37-fold at 48 h post-infection (hpi), StPDR3 was expressed (4-5-fold) at 24 and 48 hpi and then rapidly decreased, while StPDR4 RNA accumulation was stimulated (about 4-fold) at 12 and 24 hpi, decreased at 48 hpi and increased again at 96 hpi. We discuss the role of StPDR1-4 genes in response to pathogens and abiotic stresses.

Phytotoxicity, not nitrogen immobilization, explains plant litter inhibitory effects: evidence from solid-state 13C NMR spectroscopy

Litter decomposition provides nutrients that sustain ecosystem productivity, but litter may also hamper root proliferation. The objectives of this work were to assess the inhibitory effect of litter decomposition on seedling growth and root proliferation; to study the role of nutrient immobilization and phytotoxicity; and to characterize decomposing litter by (13)C NMR spectroscopy. A litter-bag experiment was carried out for 180 d with 16 litter types. Litter inhibitory effects were assessed by two bioassays: seed germination and root proliferation bioassays. Activated carbon (C) and nutrient solutions were used to evaluate the effects of phytotoxic factors and nutrient immobilization. An inhibitory effect was found for all species in the early phase of decomposition, followed by a decrease over time. The addition of activated C to litter removed this inhibition. No evidence of nutrient immobilization was found in the analysis of nitrogen dynamics. NMR revealed consistent chemical changes during decomposition, with a decrease in O-alkyl and an increase in alkyl and methoxyl C. Significant correlations were found among inhibitory effects, the litter decay rate and indices derived from NMR. The results show that it is possible to predict litter inhibitory effects across a range of litter types on the basis of their chemical composition.

Isolation of the orthologue of the cerato-ulmin gene in Ophiostoma quercus and characterization of the purified protein

Ophiostoma quercus is an ophiostomatoid fungus strictly related to the Ophiostoma's (O. ulmi, O. novo-ulmi, and O. himal-ulmi) that cause Dutch elm disease (DED). O. quercus has a number of morphological characteristics in common with the DED pathogens, and is a well-known and economically important sapstaining fungus occurring worldwide on hardwoods and commercially produced pines, and causes typical cankers on oak stems. In elm trees O. quercus can survive for months without causing any disease symptoms. DED fungi produce cerato-ulmin (CU), a class II hydrophobin, which is generally considered as the main toxin potentially involved in various phases of the DED pathogenesis. In the present work we isolated and sequenced the orthologue of the cu gene in the O. quercus isolates H988, H1042, and H2053. Moreover the CU protein from O. quercus isolate H988 was also purified and characterized. Sequence analysis showed that there is a pronounced difference between the whole cu gene region of O. quercus and the homologous fragments of the DED-causing species O. ulmi, O. novo-ulmi, and O. himal-ulmi. It also appeared that differences in the structural conformation of the promoter were unlikely to play a role in the modulation of the transcript level and that, for O. quercus, differences in CU production did not result from the potential different regulation levels. Clear differences were shown in the transcriptional unit of the cu genes and in the amino acid sequences among all the CUs. The purified O. quercus CU was separated using matrix-assisted laser desorption ionization/time of flight (MALDI-TOF) spectrometry into seven forms of increasing molecular weight from 7190 to 7724Da. The hydrophobicity profiles indicated that two regions of the O. quercus CU protein were more hydrophobic than the corresponding regions of the CUs of the DED fungi. The O. quercus CUs had theoretical isoelectric point values similar to those of the DED fungi. Finally, the contradiction between the consistent differences between these four Ophiostoma species in the cu gene region and in the CU proteins and their strict phylogenetic relationship is discussed.

Saponins from Allium minutiflorum with antifungal activity

Three saponins, named minutoside A (1), minutoside B (2), minutoside C (3), and two known sapogenins, alliogenin and neoagigenin, were isolated from the bulbs of Allium minutiflorum Regel. Elucidation of their structure was carried out by comprehensive spectroscopic analyses, including 2D NMR spectroscopy and mass spectrometry. The structures of the new compounds were identified as (25R)-furost-2alpha,3beta,6beta,22alpha,26-pentaol 3-O-[beta-D-xylopyranosyl-(1-->3)-O-beta-D-glucopyranosyl-(1-->4)-O-beta-D-galactopyranosyl] 26-O-beta-D-glucopyranoside (1), (25S)-spirostan-2alpha,3beta,6beta-triol 3-O-beta-D-xylopyranosyl-(1-->3)-O-beta-D-glucopyranosyl-(1-->4)-O-beta-D-galactopyranoside (2), and (25R)-furost-2alpha,3beta,5alpha,6beta,22alpha,26-esaol 3-O-[beta-D-xylopyranosyl-(1-->3)-O-beta-D-glucopyranosyl-(1-->4)-O-beta-D-galactopyranosyl] 26-O-beta-D-glucopyranoside (3). The isolated compounds were evaluated for their antimicrobial activity. All the novel saponins showed a significant antifungal activity depending on their concentration and with the following rank: minutoside B>minutoside C>>minutoside A. No appreciable antibacterial activity was recorded. The possible role of these saponins in plant-microbe interactions is discussed.

Study of the three-way interaction between Trichoderma atroviride, plant and fungal pathogens by using a proteomic approach

The main molecular factors involved in the complex interactions occurring between plants (bean), two different fungal pathogens (Botrytis cinerea, Rhizoctonia solani) and an antagonistic strain of the genus Trichoderma were investigated. Two-dimensional (2-D) electrophoresis was used to analyze separately collected proteomes from each single, two- or three-partner interaction (i.e., plant, pathogenic and antagonistic fungus alone and in all possible combinations). Differential proteins were subjected to mass spectrometry and in silico analysis to search for homologies with known proteins. In the plant proteome, specific pathogenesis-related proteins and other disease-related factors (i.e., potential resistance genes) seem to be associated with the interaction with either one of the two pathogens and/or T. atroviride. This finding is in agreement with the demonstrated ability of Trichoderma spp. to induce systemic resistance against various microbial pathogens. On the other side, many differential proteins obtained from the T. atroviride interaction proteome showed interesting homologies with a fungal hydrophobin, ABC transporters, etc. Virulence factors, like cyclophilins, were up-regulated in the pathogen proteome during the interaction with the plant alone or with the antagonist too. We isolated and confidently identified a large number of protein factors associated to the multi-player interactions examined.

Major secondary metabolites produced by two commercial Trichoderma strains active against different phytopathogens

AIMS

Trichoderma harzianum strains T22 and T39 are two micro-organisms used as active agents in a variety of commercial biopesticides and biofertilizers and widely applied amongst field and greenhouse crops. The production, isolation, biological and chemical characterization of the main secondary metabolites produced by these strains are investigated.

METHODS AND RESULTS

Of the three major compounds produced by strain T22, one is a new azaphilone that shows marked in vitro inhibition of Rhizoctonia solani, Pythium ultimum and Gaeumannomyces graminis var. tritici. In turn, filtrates from strain T39 were demonstrated to contain two compounds previously isolated from other T. harzianum strains and a new butenolide. The production of the isolated metabolites was also monitored by liquid chromatography/mass spectrometry during in vitro interaction with R. solani.

CONCLUSIONS

This paper reports the isolation and characterization of the main secondary metabolites obtained from culture filtrates of two T. harzianum strains and their production during antagonistic interaction with the pathogen R. solani.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is the first work on secondary metabolites produced by the commercially applied strains T22 and T39. Our results provide a better understanding of the metabolism of these fungi, which are both widely used as biopesticides and/or biofertilizers in biocontrol.

The Molecular Biology of the Interactions Between Trichoderma spp., Phytopathogenic Fungi, and Plants

ABSTRACT Trichoderma-based biofungicides are a reality in agriculture, with more than 50 formulations today available as registered products worldwide. Several strategies have been applied to identify the main genes and compounds involved in this complex, three-way cross-talk between the fungal antagonist, the plant, and microbial pathogens. Proteome and genome analysis have greatly enhanced our ability to conduct holistic and genome-based functional studies. We have identified and determined the role of a variety of novel genes and gene-products, including ABC transporters, enzymes and other proteins that produce or act as novel elicitors of induced resistance, proteins responsible for a gene-for-gene avirulent interaction between Trichoderma spp. and plants, mycoparasitism-related inducers, plant proteins specifically induced by Trichoderma, etc. We have transgenically demonstrated the ability of Trichoderma spp. to transfer heterologous proteins into plant during root colonization, and have used green fluorescent protein and other markers to study the interaction in vivo and in situ between Trichoderma spp. and the fungal pathogen or the plant.

The Molecular Biology of the Interactions Between Trichoderma spp., Phytopathogenic Fungi, and Plants

ABSTRACT Trichoderma-based biofungicides are a reality in agriculture, with more than 50 formulations today available as registered products worldwide. Several strategies have been applied to identify the main genes and compounds involved in this complex, three-way cross-talk between the fungal antagonist, the plant, and microbial pathogens. Proteome and genome analysis have greatly enhanced our ability to conduct holistic and genome-based functional studies. We have identified and determined the role of a variety of novel genes and gene-products, including ABC transporters, enzymes and other proteins that produce or act as novel elicitors of induced resistance, proteins responsible for a gene-for-gene avirulent interaction between Trichoderma spp. and plants, mycoparasitism-related inducers, plant proteins specifically induced by Trichoderma, etc. We have transgenically demonstrated the ability of Trichoderma spp. to transfer heterologous proteins into plant during root colonization, and have used green fluorescent protein and other markers to study the interaction in vivo and in situ between Trichoderma spp. and the fungal pathogen or the plant.

Safety of cisplatin after severe hypersensitivity reactions to carboplatin in patients with recurrent ovarian carcinoma

BACKGROUND

Carboplatin is a milestone drug against ovarian carcinoma; it is used both in front-line and second-line chemotherapy. Hypersensitivity reactions to carboplatin may occur during the treatment as salvage therapy. The purpose of this study was to describe the feasibility of the replacing of carboplatin with cisplatin in patients presenting with severe hypersensitivity reactions to carboplatin.

PATIENTS AND METHODS

Ten consecutive patients with platinum-sensitive, recurrent ovarian carcinoma, presenting with moderate/severe hypersensitivity reactions to carboplatin were treated with cisplatin 60 mg/m2 from January 2000 to December 2002. Hypersensitivity reactions consisted of respiratory distress (chest tightness, wheezing, dyspnea), urticaria/erythema with tachycardia, facial swelling and hypotension.

RESULTS

The total number of cisplatin cycles given was 44 (range 2-5). The treatment with cisplatin was generally well tolerated. No serious allergic reactions occurred. A mild allergic reaction was recorded (urticaria) in only one case, after one cycle of cisplatin, and the patient was not rechallenged because of progressive disease. No reductions of chemotherapy doses were needed.

CONCLUSION

To date, platinum-based regimens remain the most effective treatment in recurrent platinum-sensitive ovarian cancer with a high rate of objective responses. Although our experience is limited, we suggest that, under anesthesiologic surveillance and providing immunologic blockade, the replacement of carboplatin salvage therapy with cisplatin can be considered a safe therapeutic strategy in patients who cannot continue carboplatin due to allergic reactions.

Synergism between fungal enzymes and bacterial antibiotics may enhance biocontrol

The interactions between biocontrol fungi and bacteria may play a key role in the natural process of biocontrol, although the molecular mechanisms involved are still largely unknown. Synergism can occur when different agents are applied together, and cell wall degrading enzymes (CWDEs) produced by fungi can increase the efficacy of bacteria. Pseudomonas spp. produce membrane-disrupting lipodepsipeptides (LDPs) syringotoxins (SP) and syringomycins (SR). SR are considered responsible for the antimicrobial activity, and SP for the phytotoxicity. CWDEs of Trichoderma spp. synergistically increased the toxicity of SP25-A or SRE purified from P. syringae against fungal pathogens. For instance, the fungal enzymes made Botrytis cinerea and other phytopathogenic fungi, normally resistant to SP25-A alone, more susceptible to this antibiotic. Pseudomonas produced CWDEs in culture conditions that allow the synthesis of the LDPs. Purified bacterial enzymes and metabolites were also synergistic against fungal pathogens, although this mixture was less powerful than the combination with the Trichoderma CWDEs. The positive interaction between LDPs and CWDEs may be part of the biocontrol mechanism in some Pseudomonas strains, and co-induction of different antifungal compounds in both biocontrol bacteria and fungi may occur.

Pseudomonas lipodepsipeptides and fungal cell wall-degrading enzymes act synergistically in biological control

Pseudomonas syringae pv. syringae strain B359 secreted two main lipodepsipeptides (LDPs), syringomycin E (SRE) and syringopeptin 25A (SP25A), together with at least four types of cell wall-degrading enzymes (CWDEs). In antifungal bioassays, the purified toxins SRE and SP25A interacted synergistically with chitinolytic and glucanolytic enzymes purified from the same bacterial strain or from the biocontrol fungus Trichoderma atroviride strain P1. The synergism between LDPs and CWDEs occurred against all seven different fungal species tested and P. syringae itself, with a level dependent on the enzyme used to permeabilize the microbial cell wall. The antifungal activity of SP25A was much more increased by the CWDE action than was that of the smaller SRE, suggesting a stronger antifungal role for SP25A. In vivo biocontrol assays were performed by using P. syringae alone or in combination with T. atroviride, including a Trichoderma endochitinase knock-out mutant in place of the wild type and a chitinase-specific enzyme inhibitor. These experiments clearly indicate that the synergistic interaction LDPs-CWDEs is involved in the antagonistic mechanism of P. syringae, and they support the concept that a more effective disease control is given by the combined action of the two agents.

Purification and properties of two chitinolytic enzymes of Serratia plymuthica HRO-C48

The chitinolytic rhizobacterium Serratia plymuthica HRO-C48 was previously selected as a biocontrol agent of phytopathogenic fungi. One endochitinase (E.C. 3.2.1.14), CHIT60, and one N-acetyl-beta-1,4- D-hexosaminidase (E.C. 3.2.1.52), CHIT100, were purified and characterized. The endochitinase CHIT60, with an apparent molecular mass of 60.5 kDa, had a N-terminal amino acid sequence highly similar to that of chitinases A from Serratia liquefaciens and Serratia marcescens. The enzyme activity had its peak at 55 degrees C and pH 5.4, and increased by more than 20% in the presence of 10 mM Ca(2+), Co(2+) or Mn(2+). Activity was inhibited by 80% in the presence of 10 mM Cu(2+). CHIT100 appeared to be a monomeric enzyme with a molecular mass of 95.6 kDa and a pI of 6.8. Optimal activity was obtained at 43 degrees C and pH 6.6, and decreased by more than 90 % in the presence of 10 mM Co(2+) or Cu(2+). CHIT100 (100 microg ml(-1)) inhibited spore germination and germ tube elongation of the phytopathogenic fungus Botrytis cinerea by 28 % and 31.6 %, respectively. With CHIT60 (100 microg ml(-1)), the effect was more pronounced: 78 % inhibition of of germination and 63.9 % inhibition of germ tube elongation.

Simulation of mercury capture by activated carbon injection in incinerator flue gas. 2. Fabric filter removal

Following a companion paper focused on the in-duct mercury capture in incinerator flue gas by powdered activated carbon injection, this paper is concerned with the additional mercury capture on the fabric filter cake, relevant to baghouse equipped facilities. A detailed model is presented for this process, based on material balances on mercury in both gaseous and adsorbed phases along the growing filter cake and inside the activated carbon particles,taking into account mass transfer resistances and adsorption kinetics. Several sorbents of practical interest have been considered, whose parameters have been evaluated from available literature data. The values and range of the operating variables have been chosen in order to simulate typical incinerators operating conditions. Results of simulations indicate that, contrary to the in-duct removal process, high mercury removal efficiencies can be obtained with moderate sorbent consumption, as a consequence of the effective gas/sorbent contacting on the filter. Satisfactory utilization of the sorbents is predicted, especially at long filtration times. The sorbent feed rate can be minimized by using a reactive sorbent and by lowering the filter temperature as much as possible. Minor benefits can be obtained also by decreasing the sorbent particle size and by increasing the cleaning cycle time of the baghouse compartments. Reverse-flow baghouses were more efficient than pulse-jet baghouses, while smoother operation can be obtained by increasing the number of baghouse compartments. Model results are compared with available relevant full scale data.

Simulation of mercury capture by activated carbon injection in incinerator flue gas. 1. In-duct removal

A detailed model for the in-duct mercury capture in incinerator flue gas by powdered activated carbon injection is presented. Material balances on mercury in both gaseous and adsorbed phases are carried out along the duct length and inside the activated carbon particles, taking into account mass transfer resistances and adsorption kinetics. The set of the coupled partial differential equations is transformed by means of an orthogonal collocation technique and integrated using a Runge-Kutta method with adaptive stepsize control. The model has been applied to several sorbents of practical interest, whose parameters have been evaluated from available literature data. The values and range of the operating variables have been chosen in order to simulate typical incinerators operating conditions. Results of simulations indicate that large sorbent loadings in the duct are needed to obtain high mercury removal efficiencies, due to the short residence times. As a consequence very low utilization of the sorbents is achieved in any case. To minimize the sorbent feed rate it is particularly advisable to use a reactive sorbent and to lower the operating temperature as much as possible. Improvements in the mercury capture performance can be obtained also by increasing the in-duct particles residence time and by decreasing the sorbent particles size. Model results are compared with available relevant full scale data.

Cloning, sequence and structure of a gene encoding an antifungal glucan 1,3-beta-glucosidase from Trichoderma atroviride (T. harzianum)

A gene (gluc78) encoding an antifungal glucan 1,3-beta-glucosidase was cloned from strain P1 of the biocontrol fungus Trichoderma atroviride (formerly T. harzianum). A putative regulatory sequence upstream from the coding region was cloned using single-strand extension from a primer in the known portion of the gene, circularized with T4 ligase, and then reamplified with PCR to generate double-stranded DNA. The entire genomic DNA sequence consisted of 3440 bp, with 559 and 579 bp, respectively, in 5' and 3' untranslated regions. The transcription unit contains a single intron, positioned in the 5' untranslated region. The gene encodes for a protein of 770 aa, including a 40 aa signal peptide. Symmetry between the first and second halves of the mature protein was found. The gene is present as a single copy in T. atroviride and a similar gene also is present in T. harzianum and T. virens. The encoded protein has similarity to a small group of sequences from filamentous fungi and no significant similarity to 1,3-beta-glucanases or glucosidases from other organisms. Northern analysis indicates that the gene is repressed in the presence of 3% glucose and expressed in media containing 0.1% of the sugar. Laminarin (0.1%) enhances expression after 18 h and other polymers such as scleroglucan and pustulan may enhance expression after 40 h of growth.

Functional expression of the gene cu, encoding the phytotoxic hydrophobin cerato-ulmin, enables Ophiostoma quercus, a nonpathogen on elm, to cause symptoms of Dutch elm disease

We studied the involvement of the phytotoxic hydrophobin cerato-ulmin (CU) in pathogenesis and virulence of Dutch elm disease (DED) by expressing its encoding gene (cu) in Ophiostoma quercus, a nonpathogenic species on elm closely related to the DED pathogens O. ulmi and O. novo-ulmi. The production of the toxin was quantitatively determined in culture filtrates and in mycelial extracts of the transformants. Production of CU in vitro was associated with the ability to cause typical DED symptoms, consisting of foliar yellow and wilting and vascular tissue discoloration on a moderately resistant elm genotype. The presence of CU was monitored by enzyme-linked immunosorbent assay in symptomatic leaves of plants inoculated with O. quercus transformants expressing CU and found to be associated with wilt symptoms. In general, the virulence of the cu-expressing transformants, as measured in terms of vascular discoloration and percentage of defoliation, was lower than that of the mildly pathogenic isolate E2 of O. ulmi. However, one transformant (C39) displayed a virulence level intermediate between that of E2 and 182, a highly virulent isolate of O. novo-ulmi. Our results indicate that CU production influences virulence in nonaggressive strains of Ophiostoma fungi.

Genes from mycoparasitic fungi as a source for improving plant resistance to fungal pathogens

Disease resistance in transgenic plants has been improved, for the first time, by the insertion of a gene from a biocontrol fungus. The gene encoding a strongly antifungal endochitinase from the mycoparasitic fungus Trichoderma harzianum was transferred to tobacco and potato. High expression levels of the fungal gene were obtained in different plant tissues, which had no visible effect on plant growth and development. Substantial differences in endochitinase activity were detected among transformants. Selected transgenic lines were highly tolerant or completely resistant to the foliar pathogens Alternaria alternata, A. solani, Botrytis cinerea, and the soilborne pathogen Rhizoctonia solani. The high level and the broad spectrum of resistance obtained with a single chitinase gene from Trichoderma overcome the limited efficacy of transgenic expression in plants of chitinase genes from plants and bacteria. These results demonstrate a rich source of genes from biocontrol fungi that can be used to control diseases in plants.

Simultaneous detection of cucumber mosaic virus, tomato mosaic virus and potato virus Y by flow cytometry

The simultaneous detection is described of cucumber mosaic virus (CMV), potato virus Y (PVY) and tomato mosaic virus (ToMV) by flow cytometry. Extracts from leaves of healthy and CMV or PVY infected plants were incubated with latex particles, each with a diameter of 3 microm. Extracts from ToMV infected or uninfected plants, however, were incubated with particles, each with a diameter of 6 microm. Beads were washed and incubated in succession with primary and secondary antibodies, the latter labeled with phycoerythrin (PE) or fluorescein (FITC). CMV and PVY were distinguished on the basis of the fluorescence emitted by FITC and PE; ToMV was distinguished from CMV and PVY on the basis of the different diameter (6 microm) of the particles on which it was adsorbed. The three viruses were detected also by another approach. Latex particles with a diameter of 3, 6 and 10 microm were separately sensitized with antibodies specific for CMV, PVY and ToMV. An equal number of sensitized particles was mixed and incubated with the plant extracts containing the three viruses and then with anti-CMV, anti-PVY and anti-ToMV antibodies labeled with FITC. The study describes also a virus purification method based on the use of antibody coated latex particles. The method is simple technically and applicable to the purification of large as well as minute amounts of different viruses (CMV, PVY and ToMV).

Identification by flow cytometry of seiridin, one of the main phytotoxins produced by three Seiridium species pathogenic to cypress

Seiridin (SE), one of the main phytotoxins produced in vitro by Seiridium species pathogenic to cypress, was oxidized and the corresponding ketone derivative covalently linked to bovine serum albumin (BSA). The conjugate (SE-BSA) was used to prepare an antiserum to SE. The antibodies were absorbed with BSA and their specificity was assayed by ELISA and flow cytometry against SE, iso-seiridin (ISE), a structural isomer of SE, and some derivatives of these two metabolites. The antibodies tested in a competitive indirect ELISA did not show any binding activity to SE, ISE and their derivatives. The cytometry test, instead, was successful. SE-BSA and SE showed the highest binding activity with the antibodies. SE derivatives having a shift on the adjacent carbon, oxidation, or acetylation of the hydroxy group of the heptyl side chain at C-4 or conversion of the gamma-lactone in the corresponding planar furane ring reacted less than SE. The 2'-dansylhydrazoneSE and the 3,4-dihydroSE having a bulky group attached to the heptyl side chain and a saturated lactone ring, respectively, showed a weak reactivity. SE derivatives in which the gamma-lactone ring was destroyed and ISE derivatives presenting the shift of the hydroxy group at C-3' and another structural modification had no binding activity.

Detection of antibodies to Staphylococcus aureus in water buffalo milk by flow cytometry

An assay has been developed to detect antibodies to Staphylococcus aureus in water buffalo milk by flow cytometry. The method was the protein A-deficient strain Wood 46 of S aureus incubated with milk samples and fluorescein-labelled rabbit anti-water buffalo antiserum. The assay can detect antibodies when the pathogen is not detectable by bacterial tests and can determine the antibody titre directly on undiluted samples.