Carmen Sara Hernández Rodríguez

• PhD
• Assistant Professor / Senior Researcher at University of Valencia

The ectoparasitic mite Varroa destructor remains a great threat for the beekeeping industry, for example contributing to excessive winter colony loss in Canada. For decades, beekeepers have sequentially used the registered synthetic varroacides tau-fluvalinate, coumaphos, amitraz, and flumethrin, leading to the risk of resistance evolution in the m...

BACKGROUND The acaricide amitraz is now used intensively in many regions to control the honey bee parasite, Varroa destructor, because of the reduced efficacy of pyrethroids and coumaphos caused by resistance evolution. The continued application of amitraz in recent years exerts a very high selection pressure on mites, favouring the evolution of re...

Bacillus cereus G9241 was isolated from a welder who survived a pulmonary anthrax-like disease. Strain G9241 carries two virulence plasmids, pBCX01 and pBC210, as well as an extrachromosomal prophage, pBFH_1. pBCX01 has 99.6% sequence identity to pXO1 carried by Bacillus anthracis and encodes the tripartite anthrax toxin genes and atxA, a mammalian...

BACKGROUND The parasitic mite, Varroa destructor (Anderson and Trueman), is a leading cause of honey bee colony losses around the world. Application of miticides such as amitraz are often the primary method of Varroa control in commercial beekeeping operations in the United States. It is likely that excessive and exclusive amitraz application has l...

Bacillus cereus G9241 was isolated from a Louisiana welder suffering from an anthrax-like infection. The organism carries two transcriptional regulators that have previously been proposed to be incompatible with each other in Bacillus anthracis: the pleiotropic transcriptional regulator PlcR found in most members of the Bacillus cereus group but tr...

The Bacillus cereus-Bacillus anthracis 'cross-over' strain Bacillus cereus G9241 carries two virulence plasmids, pBCX01 and pBC210, as well as an extrachromosomal prophage, pBFH1. pBCX01 has 99.6 percent sequence identity to pXO1 carried by B. anthracis and encodes the tripartite anthrax toxin genes and atxA, a mammalian virulence transcriptional r...

The plcR gene, which encodes the pleiotropic transcriptional regulator of secreted proteins found in most members of the Bacillus cereus group, is truncated in all Bacillus anthracis isolates. The current dogma suggests this truncation was evolved to accommodate the acquisition of the anthrax toxin regulator, AtxA. However, the B. cereus / B. anthr...

Varroa destructor is considered a major reason for high loss rate of Western honey bee ( Apis mellifera ) colonies. To prevent colony losses caused by V. destructor, it is necessary to actively manage the mite population. Beekeepers, particularly commercial beekeepers, have few alternative treatments other than synthetic acaricides to control the p...

Varroa destructor is considered a major reason for high loss rate of Western honey bee ( Apis mellifera ) colonies. To prevent colony losses caused by V. destructor it is necessary to actively manage the mite population. Beekeepers, particularly commercial beekeepers, have few alternative treatments other than synthetic acaricides to control the pa...

Simple Summary Varroa destructor, a parasitic mite of Apis mellifera, is causing severe damages to honey bee colonies worldwide. There are very few acaricides available to manage the parasite, and so the evolution of the mite’s resistance to acaricides poses a serious threat to controlling the mite. Using a combined approach that includes bioassays...

Varroosis is the disease caused by the ectoparasitic mite Varroa destructor, one of the most destructive diseases of honeybees. In Spain, there is great concern because there are many therapeutic failures after acaricide treatments intended to control varroosis outbreaks. In some of these cases it is not clear whether such failures are due to the e...

The ectoparasitic honey bee mite Varroa destructor Anderson & Trueman (Acari: Varroidae) is one of the major concerns for worldwide beekeeping. The use of synthetic pyrethroids for controlling the mite was among the most popular treatments until resistance evolved in the mid 1990’s. In Iran, beekeepers are dealing with the parasite and they also us...

Vip3 vegetative insecticidal proteins from Bacillus thuringiensis are an important tool for crop protection against caterpillar pests in IPM strategies. While there is wide consensus on their general mode of action, the details of their mode of action are not completely elucidated and their structure remains unknown. In this work the alanine scanni...

A significant share of the current seasonal losses of honey bee colonies can be attributed to the ectoparasitic mite Varroa destructor. Its direct feeding behaviour and virus vectoring decimate the colony until collapse if there is no effective control management in place. The synthetic pyrethroids such as tau-fluvalinate and flumethrin were intens...

The Vip3Ca protein, discovered in a screening of Spanish collections of Bacillus thuringiensis, was known to be toxic to Chrysodeixis chalcites, Mamestra brassicae and Trichoplusia ni. In the present study, its activity has been tested with additional insect species and we found that Cydia pomonella is moderately susceptible to this protein. Vip3Ca...

Binding studies using (125)I-Cry9Ca and biotinylated-Cry1Ba proteins showed the occurrence of independent binding sites for these proteins in Ostrinia nubilalis. Our results, along with previously available binding data, indicate that combinations of Cry1A or Cry1Fa proteins with Cry1Ba and/or Cry9Ca could be a good strategy for the resistance mana...

First generation of insect-protected transgenic corn (Bt-corn) was based on the expression of Cry1Ab or Cry1Fa proteins. Currently, the trend is the combination of two or more genes expressing proteins that bind to different targets. In addition to broadening the spectrum of action, this strategy helps to delay the evolution of resistance in expose...

Autoradiography of the 125I-labeled Cry proteins. Only the two first fractions eluting from the desalting column are shown. (A) Cry1A.105, (B) Cry1Ab, and (C) Cry1Fa. Arrows indicate the position of the Cry protein. (TIF)

Purification of Cry1A.105 by anion-exchange chromatography. (A) Chromatogram indicating the start and end of the injection (broken vertical lines), the linear gradient of 1 M NaCl (inclined line) and the absorbance profile at 280 nm; the peak corresponding to Cry1A.105 is marked with an arrow. (B) SDS-PAGE with Coomassie blue staining of some of th...

Vip3Aa, Vip3Ad, Vip3Ae, and Vip3Af proteins from Bacillus thuringiensis were tested for their toxicity against Spodoptera frugiperda and Agrotis ipsilon. Vip3Ad was non-toxic to the two species. Vip3Ae and Vip3Af were significantly more toxic than Vip3Aa against S. frugiperda, both as protoxins and as toxins. Against A. ipsilon, Vip3Ae protoxin was...

Three vip3 genes were identified in two Bacillus thuringiensis Spanish collections. Sequence analysis revealed a novel Vip3 protein class (Vip3C). Preliminary bioassays of larvae from 10 different lepidopteran species indicated that Vip3Ca3 caused more than 70% mortality in four species after 10 days at 4 μg/cm2.

Previous studies reported “mode 1” Bacillus thuringiensis resistance in a colony of diamondback moths (NO-QA), and recently, this resistance has been mapped to an ABC transporter (ABCC2) locus. We report the lack of binding of Cry1Fa to insects derived from this colony and compare our data with those from other insects with ABCC2-associated resista...

Cosmid gene transcription is similar to that in the parent strain Pl W14. Comparisons of the transcription of genes present on c1AH10 in E. coli and in the original strain P. luminescens W14. RT-PCR amplification from total RNA prepared from equivalent cell numbers at different points in the growth curve in vitro at 30°C shaking in LB medium. Note...

In Pl W14, Pdl1 and Orf53 are not released into the supernatant. Western blots of membrane (m), soluble cytoplasm+periplasm (sol) and supernatant (s) fractions from Pl W14 over-expressing C-terminally his-tagged Pdl1 (A) and Orf53 (B) from the arabinose inducible pBAD30 expression vector. Samples were taken at 3, 24 and 48 hours and continued arabi...

Pdl has potential protease and lipase domains. Alignment of the predicted amino acid sequences of Pl W14 Pdl1 and Pdl2 (Genbank AY144119), with predicted products of the A. oryzae mdlB gene (Genbank D85895) and a V. cholerae hypothetical open reading frame, VC1418 (Genbank AE004220). The presence of the presumptive serine protease-like catalytic tr...

Pdl1 has no direct effect on the activity of Tcd. Mean weight gain of cohorts of M. sexta neonates (n = 10) fed different Tcd containing cell fractions (soluble, washed whole cells or supernatants) which had been pre-incubated for 1 h at 28°C with sonicated cell extracts from either an induced E. coli pBAD30-pdl1 expression construct (Pdl1) or an E...

The effects of Pdl1 and Orf53 over-expression on native protein release in E. coli. The effect of pdl1, pdl1+orf54 and pdl+orf54+orf53 pBAD30 expression constructs on supernatant proteins released by the recombinant E. coli. All genes have their native Shine-Dalgarno sequences. Size markers are also shown (x). Note Pdl1 induces the release of sever...

TcdB1 expression in Pl W14 and the cosmid clone. Expression was tracked using an anti-peptide raised against a peptide located in the C-terminal region of the B-subunit TcdB1 (aa856-YSSSEEKPFSPPNDC-aa869). (A) A qualitative comparison of culture supernatants of wild type Pl W14 and a strain in which tcdA and tcdB have been deleted (D-). The absence...

Trans-complementation of the pdl-knock out cosmid strain restores the Tcd release phenotype. Mean weight gain of cohorts of M. sexta neonates (n = 12) fed with whole cultures, supernatants or cells from 72 hour old 28°C grown cultures of E. coli containing the CVI-wt cosmid (with transposon inserts in the pWEB backbone), the pdl1 KO1-mutant cosmid...

Oral toxicity of cosmid transposon mutants in Pl TT01. (A) Map of cosmid c1AH10 showing transposon insertion points tested for supernatant oral toxicity when transformed into P. luminescens TT01. Filled inverted triangles represent transposon insertion points that maintained toxicity (T = toxic), while those which abolished toxicity are shown as op...

Pdl homologues are associated with other toxin secretion genes in diverse bacteria. (A) A pdl-orf54 island of P. asymbioticaATCC43949 identified using RVA screening exhibiting insect toxicity on injection. Colour coding identifies homologous genes. Genbank locus tag numbers are given. The pdl and vgrG homologues were shown to be responsible for the...

The Toxin Complex (TC) is a large multi-subunit toxin first characterized in the insect pathogens Photorhabdus and Xenorhabdus, but now seen in a range of pathogens, including those of humans. These complexes comprise three protein subunits, A, B and C which in the Xenorhabdus toxin are found in a 4:1:1 stoichiometry. Some TCs have been demonstrate...

Cry1Fa insecticidal protein was successfully radiolabeled with (125)I-Na. Specific binding to brush border membrane vesicles was shown for the lepidopteran species Ostrinia nubilalis, Spodoptera frugiperda, Spodoptera exigua, Helicoverpa armigera, Heliothis virescens, and Plutella xylostella. Homologous competition assays were performed to obtain e...

Background: Evolution of resistance by target pests is the main threat to the long-term efficacy of crops expressing Bacillus thuringiensis (Bt) insecticidal proteins. Cry2 proteins play a pivotal role in current Bt spray formulations and transgenic crops and they complement Cry1A proteins because of their different mode of action. Their presence...

Four collections comprising 507 strains of Bacillus thuringiensis have been analysed in this study. A different ecological origin characterizes each collection. Collection No. 1 was established from soil, dust, and grain samples from Spanish agricultural and non-cultivated soil, silos, and mills. Collection No. 2 is the result of a screening in oli...

To identify known vip genes and to detect potentially novel vip genes in a collection of 507 strains of Bacillus thuringiensis. Following a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) strategy, four restriction patterns were found within the vip1 family: vip1Aa1, vip1Ba1/vip1Ba2 and vip1Ca. In the screening of vip2...

The repat gene family encodes midgut proteins overexpressed in response to pathogen infection in the lepidopteran Spodoptera exigua. Up-regulation of repat genes has been observed after challenging the larvae with both Bacillus thuringiensis toxins and after infection with the baculovirus Autographa californica multiple nucleopolyhedrovirus. In our...

Vip3Aa, Vip3Af, Cry1Ab, and Cry1Fa were tested for their toxicities and binding interactions. Vip3A proteins were more toxic than Cry1 proteins. Binding assays showed independent specific binding sites for Cry1 and Vip3A proteins. Cry1Ab and Cry1Fa competed for the same binding sites, whereas Vip3Aa competed for those of Vip3Af.

The microlepidopteran Prays oleae is one of the main insect pests causing significant crop losses in the Mediterranean olive groves. Bacillus thuringiensis based insecticides are being successfully used to minimize the impact of the second and third generations of this pest. However, because of its very small size and difficulty of rearing, very fe...

For a long time, it has been assumed that the mode of action of Cry2A toxins was unique and different from that of other three-domain Cry toxins due to their apparent nonspecific and unsaturable binding to an unlimited number of receptors. However, based on the homology of the tertiary structure among three-domain Cry toxins, similar modes of actio...

Bacillus thuringiensis was isolated from 116 samples collected in high altitude potato-growing areas in Bolivia. In these regions, main potato pests are the potato tuberworm Phthorimaea operculella, and the Andean weevils Premnotrypes latithorax and Rhigopsidius tucumanus. B. thuringiensis was found in 60% of the samples. The main percentage of sam...

Binding studies using 125I-Cry1Ac and biotinylated Cry1Fa toxins indicate the occurrence of a common receptor for Cry1Ac, Cry1Fa, and Cry1Ja in Helicoverpa armigera, Helicoverpa zea, and Spodoptera exigua. Our results, along with previous binding data and the observed cases of cross-resistance, suggest that this pattern seems to be widespread among...

Binding assays with brush border membrane vesicles (BBMV) from insect midguts are commonly used in the study of the interactions between Bacillus thuringiensis Cry toxins and their receptors. Collaboration between laboratories often require that frozen insect samples are sent in dry ice. Because of customs restrictions and delays, sample thawing is...

beta-Exotoxin is a thermostable metabolite produced by some strains of Bacillus thuringiensis. Because of vertebrate toxicity, most commercial preparations of B. thuringiensis are prepared from isolates that do not produce beta-exotoxin. The aim of the present study was to find out the possible relationship between serovars of B. thuringiensis and...

El objetivo de este trabajo es la determinación del potencial de los productos basados en B. thuringiensis para el control del taladro del geranio, así como establecer qué proteínas Cry presentes en estos productos comerciales son los principales responsables de la toxicidad.

The current work aimed to study the presence of beta-exotoxin by high-performance liquid chromatography (HPLC) in supernatant fluids from final whole cultures of the 69 type strains and 13 subtypes of Bacillus thuringiensis strains, as well as from some insecticidal strains. Results from HPLC and bioassays with Ephestia kuhniella (Lepidoptera Pyral...

We report the identification and characterization of Ψ3Tom20, a novel processed pseudogene of the human Tom20 (hTom20) gene, which is 96.2% similarity with the hTom20 cDNA and is 5′ and 3′ truncated. In addition, we present the complete characterization of Ψ1Tom20 and Ψ2Tom20, the two other recently reported members of this pseudogene family. Compa...