Papers by Stefano Cassanelli
Journal of Economic Entomology, 2015
Aim of the study was to investigate the performance of the new insecticide "spirotetramat" as an ... more Aim of the study was to investigate the performance of the new insecticide "spirotetramat" as an alternative solution of "abamectin" for the control of Cacopsylla pyri L. (Hemiptera: Psyllidae) in the context of an IPM program in European pear, Pyrus communis L.. Laboratory bioassays for the estimation of LC 50 and LC 90 of both insecticides were performed using four populations collected in Emilia-Romagna (Italy) orchards where different pest management strategies were used (organic, integrated, and conventional). The same populations were also analyzed for the main insecticide detoxifying activities in nymphs by spectrofluorimetric in vitro assays. The performance of the two insecticides was also tested on field on one population under integrated pest management conditions. The laboratory experiments showed that the LC 90 of spirotetramat were lower than the highest field concentration allowed in Europe (172.80 mg AI liter À1 ) giving reassurance about the efficacy of the product. Concerning the abamectin, the laboratory bioassays did not show strong indications of resistance development of C. pyri populations of Emilia-Romagna. A similarity in enzyme detoxifying activity was observed in both insecticides indicating a general absence of a significant insecticide resistance. The field trial showed a high efficacy (>90 %) of spirotetramat on C. pyri already after 15 d from application, and it was significantly higher from abamectin. Overall, spirotetramat is one more choice for C. pyri control, as well as abamectin in order to minimize the risks of occurrence of insecticide resistance.
Journal of lipid research, 1993
An analysis of LDL-receptor gene was performed on an Italian patient with heterozygous familial h... more An analysis of LDL-receptor gene was performed on an Italian patient with heterozygous familial hypercholesterolemia. Restriction enzyme analysis showed that the proband was heterozygous for a deletion of 4.5 kb spanning the 5' end of exon 13 (45 nucleotide residues) to intron 15. Amplification of genomic DNA, using polymerase chain reaction (PCR), followed by direct sequencing, showed that this deletion was identical to the one reported by Lehrman et al. (1986. Proc. Natl. Acad. Sci. 83: 3679-3683). As only the normal LDL-receptor mRNA was detectable in proband fibroblasts by Northern blot, we used reverse transcription-PCR to amplify the mutant mRNA using primers complementary to exon 6 (sense) and exon 18 (antisense). The amplification of control cDNA resulted in a single fragment of 1725 nucleotides containing the normal sequence. The amplification of cDNA from the proband produced the 1725-nucleotide fragment (as in the control) and three additional fragments (F1, F2, and F...
G3: Genes|Genomes|Genetics, 2014
Sexual reproduction and breeding systems are driving forces for genetic diversity. The matingtype... more Sexual reproduction and breeding systems are driving forces for genetic diversity. The matingtype (MAT) locus represents a mutation and chromosome rearrangement hotspot in yeasts. Zygosaccharomyces rouxii complex yeasts are naturally faced with hostile low water activity (a w ) environments and are characterized by gene copy number variation, genome instability, and aneuploidy/allodiploidy. Here, we investigated sex-determination system in Zygosaccharomyces sapae diploid strain ABT301 T , a member of the Z. rouxii complex. We cloned three divergent mating type-like (MTL) a-idiomorph sequences and designated them as ZsMTLa copies 1, 2, and 3. They encode homologs of Z. rouxii CBS 732 T MATa2 (amino acid sequence identities spanning from 67.0 to 99.5%) and MATa1 (identity range 81.5-99.5%). ABT301 T possesses two divergent HO genes encoding distinct endonucleases 100% and 92.3% identical to Z. rouxii HO. Cloning of MATa-idiomorph resulted in a single ZsMTLa locus encoding two Z. rouxii-like proteins MATa1 and MATa2. To assign the cloned ZsMTLa and ZsMTLa idiomorphs as MAT, HML, and HMR cassettes, we analyzed their flanking regions. Three ZsMTLa loci exhibited the DIC1-MAT-SLA2 gene order canonical for MAT expression loci. Furthermore, four putative HML cassettes were identified, two containing the ZsMTLa copy 1 and the remaining harboring ZsMTLa copies 2 and 3. Finally, the ZsMTLa locus was 39-flanked by SLA2, suggesting the status of MAT expression locus. In conclusion, Z. sapae ABT301 T displays an aaaa genotype missing of the HMR silent cassette. Our results demonstrated that mating-type switching is a hypermutagenic process in Z. rouxii complex that generates genetic diversity de novo. This error-prone mechanism could be suitable to generate progenies more rapidly adaptable to hostile environments.
Caryologia, 2006
Aphids life cycle includes cyclical or obligate parthenogenesis, therefore low genetic variation ... more Aphids life cycle includes cyclical or obligate parthenogenesis, therefore low genetic variation is expected in these insects. Genetic diversity in crop pest aphids such as Myzus persicae, is also influenced by the extensive use of insecticides which favoured the selection of few resistant strains. In the present work, 18 M. persicae populations collected in different Italian regions, were studied by RAPD-PCR (Random Amplified Polymorphic DNA) to assess genetic variability among populations. Twelve different random primers, selected out of 24 previously investigated, were employed for genomic DNA amplification. A total of 150 fragments from the aphid M. persicae populations, and 31 fragments in two outgroups were identified. An UPGMA cluster analysis based on Nei and Li's genetic distance revealed that the M. persicae populations could be divided into two groups: aphids from Central and Southern Italy were generally located in the same cluster, while aphids from Northern Italy were more often located in the other. The presence of a positive correlation between genetic and geographical distance suggests that at least a portion of the interpopulation polymorphism evidenced could be caused by restricted gene flow.
Zoologischer Anzeiger - A Journal of Comparative Zoology, 2003
Gastrotrichs are meiobenthic invertebrates of obscure origin and unclear phylogenetic alliances. ... more Gastrotrichs are meiobenthic invertebrates of obscure origin and unclear phylogenetic alliances. Uncertainties also plague the intra-group relationship with major contrasts between the evolutionary scenarios inferred from morphology or molecules. In this study ...
Yeast, 2007
The taxonomic status and species number of the genus Zygosaccharomyces have rapidly changed in th... more The taxonomic status and species number of the genus Zygosaccharomyces have rapidly changed in the last years. In this study, two new osmotolerant Zygosaccharomyces strains isolated from traditional balsamic vinegar, viz. ABT301 and ABT601, were investigated to elucidate their taxonomic relationships with Zygosaccharomyces rouxii species. A multi-gene sequence approach was employed, including regions of the rDNA repeat [5.8S, two internal transcribed spacers (ITS) and the 26S D1/D2 domain], COX2 mitochondrial gene and two nuclear genes (SOD2 and HIS3). Cloning and sequence analysis of 5.8S-ITS rDNA revealed that these strains bear an unusual polymorphism for this region. Three highly divergent 5.8S-ITS sequences were detected, one identical to Z. rouxii, the other two showing some relatedness to Z. mellis. Sequence and gene number polymorphism was also observed for the protein-encoding nuclear genes SOD2 and HIS3, as two copies for each gene different from those found in Z. rouxii were detected. Analysis of the D1/D2 26S domain showed that ABT301 and ABT601 have only one type of D1/D2 sequence statistically different from that of Z. rouxii. The findings obtained in this work suggest that the genomic background of strains ABT301 and ABT601 is different from the other Zygosaccharomyces species. We speculated that they could belong to a new putative species related to Z. rouxii.
Pesticide Biochemistry and Physiology, 2005
The wide use of insecticides containing an esteric group selected resistant Myzus persicae popula... more The wide use of insecticides containing an esteric group selected resistant Myzus persicae populations characterised by the overproduction of one of two closely related carboxylesterases (E4 and FE4). In this paper, we present data collected from Italian population indicating that all the 22 populations analysed possess amplified FE4 gene only. The estimation of FE4 copy number, carried out by densitometric scanning of dot and Southern blots, puts in evidence that the different populations possess a gene copy number ranging from 6 to 104. Statistical analysis shows the existence of a high positive correlation between gene copy number and total esterase activity. In aphid strain with low FE4 copy number, these genes are almost totally methylated. On the contrary, aphid strains with high FE4 gene number evidenced highly variable methylation levels and absence of correlation between the number of genes and their methylation state. The same result has been observed when comparing FE4 methylation levels and esterase activity.
Pesticide Biochemistry and Physiology, 2008
In this paper we analysed the basis of insecticide resistance in 59 Italian strains of the peach ... more In this paper we analysed the basis of insecticide resistance in 59 Italian strains of the peach potato aphid Myzus persicae using both molecular and biochemical assays. Our data as a whole clearly indicate that most M. persicae strains (76.3%) have high or extremely high production of an esterase enzyme which sequester and detoxify insecticides with esteric group. Kdr genotypes conferring resistance towards pyrethoids are present in 57.7% of the analysed populations. Moreover, 26.5% of the kdr positive strains possess also the M918T ...
Pest Management Science, 2005
The peach-potato aphid Myzus persicae (Sulzer) has developed a number of insecticide resistance m... more The peach-potato aphid Myzus persicae (Sulzer) has developed a number of insecticide resistance mechanisms owing to the high selective pressure produced by world-wide insecticide treatments. Knowledge of the geographical distribution and the temporal evolution of these resistant phenotypes helps to develop suitable pest-management programs. Current understanding of the major mechanisms of resistance at the molecular level makes it possible to diagnose the presence of modified acetylcholinesterase (MACE) or knockdown resistance (kdr). This paper describes a rapid method for the identification of both resistance mechanisms in a single molecular assay by using restriction fragment length polymorphism of PCR products (RFLP-PCR) in individual as well as pooled aphids.
New England Journal of Medicine, 1999
Journal of Hepatology, 2001
Background/Aims: The actual prevalence of the main hemochromatosis (HFE) mutations in the Italian... more Background/Aims: The actual prevalence of the main hemochromatosis (HFE) mutations in the Italian adult population and their phenotypic expression have not yet been established. This information is key to advocate a mass-screening program.
Journal of Economic Entomology, 2000
Cyantraniliprole is a novel insecticide for control of multiple chewing and sucking insect pest s... more Cyantraniliprole is a novel insecticide for control of multiple chewing and sucking insect pest species including the sweetpotato whiteßy Bemisia tabaci (Gennadius), which is one of the most important polyphagous pests in tropical, subtropical, and Mediterranean regions. This study aims to evaluate the effects of cyantraniliprole on the probing behavior of B. tabaci on tomato. Electrical penetration graph data indicated that on plants treated with cyantraniliprole (foliar application), adult whiteßies of the genetic variant Q2 were not able to reach the phloem and consequently did not perform the activities represented by E1 and E2 waveforms, i.e., phloem salivation (during which inoculation of geminiviruses occurs) and phloem sap ingestion (during which geminiviruses are acquired by the whiteßies), respectively. The complete failure of B. tabaci biotype Q adults to feed from the phloem of tomato plants treated with cyantraniliprole could be explained by rapid cessation of ingestion because of the mode of action of this insecticide. Overall, these Þndings indicated that cyantraniliprole might represent a useful new tool for producers to protect tomato plants from damage by B. tabaci.
Journal of Economic Entomology, 2010
The pear psylla, Cacopsylla pyri L. (Hemiptera: Psyllidae), is a relevant pest of pear, Pyrus com... more The pear psylla, Cacopsylla pyri L. (Hemiptera: Psyllidae), is a relevant pest of pear, Pyrus communis L., trees in Emilia-Romagna region (northern Italy). The susceptibility to the insecticide abamectin was evaluated at different times of the year on C. pyri populations undergoing different control strategies within conventional, integrated, and organic farms. The tests performed were the egg spray and the topic and dip bioassay on adults. The larval mortality was evaluated by dip bioassay on treated leaves. The activity of P450-dependent monooxygenases, a relevant enzyme system involved in insecticide resistance of C. pyri, was also determined in adults by 7-ethoxycoumarin O-deethylation (ECOD assay). Tests on treated eggs and on larvae showed no significant differences in LC50 and LC90, although these values were always lower in individuals collected from organic farms in comparison with all other farms. Tests on overwintering adults revealed differences among populations, probably more related to collection time than to field pest control strategies. Unexpectedly, the ECOD assay on adults showed a slightly higher cytochrome P450 monooxygenase activity in the population undergoing organic control in comparison to others. Our results indicate that egg spray is the most reliable bioassay to verify data of open-field applications. Apparently, no resistance to abamectin has yet been developed by C. pyri in Emilia-Romagna.
Journal of Clinical Investigation, 2001
Hemochromatosis is a progressive iron overload disorder that is prevalent among individuals of Eu... more Hemochromatosis is a progressive iron overload disorder that is prevalent among individuals of European descent. It is usually inherited in an autosomal-recessive pattern and associated with missense mutations in HFE, an atypical major histocompatibility class I gene. Recently, we described a large family with autosomal-dominant hemochromatosis not linked to HFE and distinguished by early iron accumulation in reticuloendothelial cells. Through analysis of a large pedigree, we have determined that this disease maps to 2q32. The gene encoding ferroportin (SLC11A3), a transmembrane iron export protein, lies within a candidate interval defined by highly significant lod scores. We show that the iron-loading phenotype in autosomal-dominant hemochromatosis is associated with a nonconservative missense mutation in the ferroportin gene. This missense mutation, converting alanine to aspartic acid at residue 77 (A77D), was not seen in samples from 100 unaffected control individuals. We propose that partial loss of ferroportin function leads to an imbalance in iron distribution and a consequent increase in tissue iron accumulation.
Insect Biochemistry and Molecular Biology, 2006
Two strains of Cydia pomonella (L.) (Lepidoptera: Tortricidae) were selected in the lab by exposu... more Two strains of Cydia pomonella (L.) (Lepidoptera: Tortricidae) were selected in the lab by exposure to increasing concentrations of diflubenzuron (Rdfb strain) or azinphos-methyl (Raz strain).
Genetica, 2005
Chromatin organization in the holocentric chromosomes of the green apple aphid Aphis pomi has bee... more Chromatin organization in the holocentric chromosomes of the green apple aphid Aphis pomi has been investigated at a cytological level after C-banding, NOR, Giemsa, fluorochrome staining and fluorescent in situ hybridization (FISH). C-banding technique showed that heterochromatic bands are exclusively located on X chromosomes. This data represents a peculiar feature that clearly contradicts the equilocal distribution of heterochromatin typical of monocentric chromosomes. Moreover, silver staining and FISH carried out with a 28S rDNA probe localized rDNA genes on one telomere of each X chromosome; CMA3 staining reveals that these silver positive telomeres are the only GC-rich regions among A. pomi heterochromatin, whereas all other C-positive bands are DAPI positive thus containing AT-rich DNA.
Fungal Genetics and Biology, 2008
Ploidy is a fundamental genetic trait with important physiological and genomic implications. We a... more Ploidy is a fundamental genetic trait with important physiological and genomic implications. We applied complementary molecular tools to highlight differences in genome size and ploidy between Zygosaccharomyces rouxii strain CBS 732 T and other related wild strains (ATCC 42981, ABT 301, and ABT 601). The cell cycle analysis by flow cytometry revealed a genome size of 12.7 ± 0.2 Mb for strain CBS 732 T , 21.9 ± 0.2 Mb for ATCC 42981, 28.1 ± 1.3 Mb for ABT 301, and 39.00 ± 0.3 Mb for ABT 601. Moreover, karyotyping analysis showed a high variability, with wild strains having a higher number of chromosomal bands than CBS 732 T . The ploidy level was assessed comparing genome size from flow cytometry with the average haploid size from electrophoretic karyotyping. Strain CBS 732 T showed an haploid DNA content, whereas the wild strains a diploid DNA content. In addition gene probe-chromosome hybridization targeted to ZSOD genes showed that wild strains with a diploid DNA content have two ZSOD copies located on different chromosomes.
Experimental and Applied Acarology, 2012
Problems with Tetranychus urticae are frequently reported in protected crops in Italy, particular... more Problems with Tetranychus urticae are frequently reported in protected crops in Italy, particularly in roses where many introduced acaricides show a progressive loss of effectiveness. We have conducted bioassays to assess the response of some Italian strains of T. urticae to a number of acaricides. These include compounds that were widespread and frequently used in the past, but also some recently registered compounds. We investigated two T. urticae strains collected from rose growers where control failures were reported (SAN and PSE), together with a strain collected from unsprayed vegetables (BOSA). Adult females of the rose strains (SAN and PSE) were resistant to tebufenpyrad (Resistant Ratio-RR, RR(50) = 48.4 and 163.6) and fenpyroximate (RR(50) = 74.1 and 25.9) when compared to the susceptible BOSA strain. Lethal concentrations for these products were higher than the registered field rate. The PSE strain proved to be highly resistant to abamectin (RR(50) = 1,294.1). Variation in bifenazate susceptibility was detected amongst strains, but LC(90) values of SAN and PSE were still in the range of the registered field rate. In egg bioassays, the SAN and PSE strains exhibited high resistance levels to clofentezine (RR(50) = 66,473 and 170,714), hexythiazox (RR(50) = 70,244 and 159,493) and flufenoxuron (RR(50) = 61.9 and 117.9). But the recently introduced ovi/larvicides etoxazole and spirodiclofen exhibited high activity on all strains. The activity of detoxifying enzymes such as esterases, glutathione-S-transferases (GSTs) and cytochrome P450 monooxygenases (MFOs) was determined in these strains as a preliminary attempt to identify potential resistance mechanisms. Enzymatic assays showed that the rose strains exhibited 2.66 and 1.95-fold increased MFOs activity compared to the susceptible strain. Assays for GSTs revealed that only the SAN strain exhibited a significantly higher activity. In contrast, only the PSE strain showed a significant higher hydrolysis of 1-naphthyl acetate.
European Journal of Entomology, 2009
The structure of the holocentric chromosomes of the rosy apple aphid, Dysaphis plantaginea (2n = ... more The structure of the holocentric chromosomes of the rosy apple aphid, Dysaphis plantaginea (2n = 12), and pear-grass aphid, Melanaphis pyraria (2n = 8), was studied using C-banding, NOR, Giemsa and fluorochrome staining, and fluorescent in situ hybridization (FISH). Contrary to the equilocal distribution of heterochromatin typical of monocentric chromosomes, in both species C-banding evidenced a tendency of highly repetitive DNAs to be restricted to the X chromosomes. Silver staining and FISH, using a 28S rDNA probe, located rDNA genes on one telomere of each X chromosome, the only brightly fluorescent C-positive sites revealed by CMA3 staining, whereas all other heterochromatic C-bands were DAPI positive. Both species showed a noticeable amount of rDNA heteromorphism. Mitotic recombination is proposed as a possible mechanism responsible for the variation in size of rDNA.
Clinical Genetics, 2008
Severe hypercholesterolemia was found in an 11-year-old boy with no family history of familial hy... more Severe hypercholesterolemia was found in an 11-year-old boy with no family history of familial hypercholesterolemia. The reduced LDL-receptor activity in cultured skin fibroblasts (40% 125I-LDL degradation as compared with a control cell line) indicated the presence of an LDL-receptor defect. The analysis of the promoter region and the exons of LDL-receptor gene by single strand conformation polymorphism revealed an abnormal migration pattern in exon 1, which was due to a T --&gt; A transversion at nucleotide 28 of the cDNA. This novel mutation causes an arginine for tryptophane substitution at position - 12 of the signal peptide (W-12R) and introduces an AviII restriction site in exon 1. Screening of the mutation by polymerase chain reaction (PCR) amplification of exon 1 and AviII digestion revealed that none of the proband&#39;s family members carried the mutation. Non-paternity was excluded after the analysis of a battery of 14 short tandem repeats located in 13 different chromosomes. These results are consistent with the hypothesis that the proband is heterozygous for a &#39;de novo&#39; mutation of the LDL-receptor gene producing a non-conservative amino acid substitution. We suggest that the change in the net charge of the signal peptide, caused by the addition of a positively charged amino acid, impairs the co-translational translocation of the nascent receptor protein across the endoplasmic reticulum membrane.
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Papers by Stefano Cassanelli