The Experts below are selected from a list of 318 Experts worldwide ranked by ideXlab platform
V N Meyerswallen - One of the best experts on this subject based on the ideXlab platform.
-
exclusion of lhx9 as a candidate gene for sry negative xx sex reversal in the american cocker Spaniel model
Journal of Heredity, 2005Co-Authors: Suresh Pujar, Ewen Kirkness, R Van Wormer, Kumar S.d. Kothapalli, V N MeyerswallenAbstract:: XX sex reversal is known in 17 breeds of dogs. In the American cocker Spaniel, it segregates as an autosomal recessive trait, and the affected animals lack the testis determining Sry gene. In the search for an autosomal gene that causes this trait, we considered the possibility of Lhx9, a gene encoding LIM homeobox containing transcription factor 9, as a candidate gene. An American cocker Spaniel pedigree showing Sry-negative XX sex reversal phenotype was genotyped with an intronic Lhx9 microsatellite marker. Segregation of the Lhx9 marker in the pedigree indicated that a mutation in canine Lhx9 is not likely to be the cause of Sry-negative XX sex reversal. In addition, using the recently available 7.6X canine genomic sequence, we report the location and genomic organization of canine Lhx9.
-
sry negative xx sex reversal in purebred dogs
Molecular Reproduction and Development, 1999Co-Authors: V N Meyerswallen, D Schlafer, I Barr, Robin Lovellbadge, A KeyznerAbstract:The gene responsible for testis induction in normal male mammals is the Y-linked Sry. However, there is increasing evidence that other genes may have testis-determining properties. In XX sex reversal (XXSR), testis tissue develops in the absence of the Y chromosome. Previous polymerase chain reaction (PCR) assays indicated that autosomal recessive XXSR in the American cocker Spaniel is Sry-negative. In this study, genomic DNA from the breeding colony of American cocker Spaniels and from privately owned purebred dogs were tested by PCR using canine primers for the Sry HMG box and by Southern blots probed with the complete canine Sry coding sequence. Sry was not detected by either method in genomic DNA of affected American cocker Spaniels or in the majority (20/21) of affected privately owned purebred dogs. These results confirm that the autosomal recessive form of XXSR in the American cocker Spaniel is Sry-negative. In combination with previous studies, this indicates that Sry-negative XXSR occurs in at least 15 dog breeds. The canine disorder may be genetically heterogeneous, potentially with a different mutation in each breed, and may provide several models for human Sry-negative XXSR. A comparative approach to sex determination should be informative in defining the genetic and cellular mechanisms that are common to all mammals.
Lígia Miranda Ferreira Borges - One of the best experts on this subject based on the ideXlab platform.
-
brown dog tick rhipicephalus sanguineus sensu lato infestation of susceptible dog hosts is reduced by slow release of semiochemicals from a less susceptible host
Ticks and Tick-borne Diseases, 2017Co-Authors: Jaires Gomes De Oliveira Filho, Lorena Lopes Ferreira, J. A. Pickett, Michael Alexander Birkett, Andre Lucio Franceschini Sarria, Gabriel Moura Mascarin, Adalberto Perez A De Leon, Lígia Miranda Ferreira BorgesAbstract:Domestic dog breeds are hosts for the brown dog tick, Rhipicephalus sanguineus sensu lato, but infestation levels vary among breeds. Beagles are less susceptible to tick infestations than English cocker Spaniels due to enhanced production of 2-hexanone and benzaldehyde that act as volatile tick repellents. We report the use of prototype slow-release formulations of these compounds to reduce the burden of R. sanguineus s. l. on English cocker Spaniel dogs. Twelve dogs were randomly assigned to two groups with six dogs each. The treated group received collars with slow-release formulations of the compounds attached, while the control group received collars with clean formulations attached. Five environmental infestations were performed, with the number of ticks (at all stages) on the dogs being counted twice a day for 45 days. The counts on the number of tick stages found per dog were individually fitted to linear mixed effects models with repeated measures and normal distribution for errors. The mean tick infestation in the treated group was significantly lower than in the control group. For larvae and nymphs, a decrease in tick infestation was observed at the fifth count, and for adults, lower average counts were observed in all counts. The compounds did not interfere with the distribution of the ticks on the body of the dogs, as a similar percentage of ticks was found on the anterior half of the dogs (54.5% for the control group and 56.2% for the treated group). The biological and reproductive parameters of the ticks were not affected by the repellents. This study highlights for the first time the potential use of a novel allomone (repellent)-based formulation for reduction of tick infestation on susceptible dogs.
-
identification of non host semiochemicals for the brown dog tick rhipicephalus sanguineus sensu lato acari ixodidae from tick resistant beagles canis lupus familiaris
Ticks and Tick-borne Diseases, 2015Co-Authors: Lígia Miranda Ferreira Borges, Jaires Gomes De Oliveira Filho, Lorena Lopes Ferreira, J. A. Pickett, Carla Cristina Braz Louly, Michael Alexander BirkettAbstract:Studies have shown that the brown dog tick, Rhipicephalus sanguineus sensu lato, when fed on the beagle breed of dog, Canis lupus familiaris, development negatively affected in comparison with tick development after feeding on the English cocker Spaniel breed. Thus leading to the suggestion that beagle dogs are be tick-resistant dogs. Behavioural studies have demonstrated that more ticks are attracted by extracts from cocker Spaniels than from beagles and that the odour of beagles is a repellent. To test the hypothesis that resistant hosts produce repellent compounds, we undertook comparative chemical analysis on beagle odour and cocker Spaniel extracts using coupled high-resolution gas chromatography–mass spectrometry (GC–MS) and also used Petri-dish and olfactometer behavioural assays to assess the response of ticks to identified non-host compounds. The beagle odour extracts contained almost three times as many chemical compounds as cocker Spaniel samples. Several non-host compounds were identified, i.e. 2-hexanone, benzaldehyde, nonane, decane and undecane. In Petri-dish assays, 2-hexanone was repellent at 30 min at concentrations of 0.200 and 0.050 mg cm−2, whilst at 10 min, the 0.100 mg cm−2 concentration was repellent. Benzaldehyde repelled ticks at 30 min (0.200 mg cm−2) and at 5 min (0.050 mg cm−2). Undecane was repellent for R. sanguineus s.l. ticks for the first 5 min at the highest concentration tested. Nonane and decane did not show any significant repellency at any concentration or time evaluated. When 2-hexanone and benzaldehyde were combined, an increase in the repellency rate was observed, with activity comparable or better than N,N-diethyl-3-methylbenzamide (DEET). In olfactometer bioassays, a 1:1 mixture of 2-hexanone:benzaldehyde and DEET were repellent for R. sanguineus s.l. adults at the concentration of 0.200 mg cm−2. This study identified non-host semiochemicals that mediate avoidance of the beagle dog breed by R. sanguineus s.l. This finding may enable development of new approaches to control this tick.
-
Differences in the behavior of Rhipicephalus sanguineus tested against resistant and susceptible dogs
Experimental and Applied Acarology, 2010Co-Authors: Carla Cristina Braz Louly, Sara Fernandes Soares, Diana Nóbrega Silveira, Marcelo Sales Guimarães, Lígia Miranda Ferreira BorgesAbstract:To ascertain whether brown dog tick Rhipicephalus sp. infests resistant (beagle) and susceptible (English cocker Spaniel) dogs differently, five animals of each breed were maintained in a kennel whose walls were infested with 7,000 larvae, 320 nymphs, 80 males and 80 females, in 3 infestations, at 10-day intervals. Five times more ticks were found on cocker Spaniels (498) than on beagles (96). Substances were collected by rubbing pieces of clean flannel on the dogs for 15 min and these were tested for arrestment and attractiveness of ticks. Three choices were offered: cocker extract vs. control; beagle extract vs. control, and cocker extract vs. beagle extract. When allowed to choose between substances rubbed from dogs and a control, more ticks were arrested by extracts from the cockers than from beagles. In the arrestment tests with only a choice between substances from dogs of each breed, more ticks were arrested by cocker substances. To test for attraction, capsules containing adsorbent were used and the tests were carried out in a Y-olfactometer. Fifteen males and 15 females were tested, for each treatment. In the olfactometer, the ticks were not attracted to the odor of either breed, however the odor of the Beagle was apparently repellent. These results indicate that R. sanguineus can use substances from the dogs to differentiate susceptible English Cocker Spaniels from resistant Beagles.
Michael Alexander Birkett - One of the best experts on this subject based on the ideXlab platform.
-
brown dog tick rhipicephalus sanguineus sensu lato infestation of susceptible dog hosts is reduced by slow release of semiochemicals from a less susceptible host
Ticks and Tick-borne Diseases, 2017Co-Authors: Jaires Gomes De Oliveira Filho, Lorena Lopes Ferreira, J. A. Pickett, Michael Alexander Birkett, Andre Lucio Franceschini Sarria, Gabriel Moura Mascarin, Adalberto Perez A De Leon, Lígia Miranda Ferreira BorgesAbstract:Domestic dog breeds are hosts for the brown dog tick, Rhipicephalus sanguineus sensu lato, but infestation levels vary among breeds. Beagles are less susceptible to tick infestations than English cocker Spaniels due to enhanced production of 2-hexanone and benzaldehyde that act as volatile tick repellents. We report the use of prototype slow-release formulations of these compounds to reduce the burden of R. sanguineus s. l. on English cocker Spaniel dogs. Twelve dogs were randomly assigned to two groups with six dogs each. The treated group received collars with slow-release formulations of the compounds attached, while the control group received collars with clean formulations attached. Five environmental infestations were performed, with the number of ticks (at all stages) on the dogs being counted twice a day for 45 days. The counts on the number of tick stages found per dog were individually fitted to linear mixed effects models with repeated measures and normal distribution for errors. The mean tick infestation in the treated group was significantly lower than in the control group. For larvae and nymphs, a decrease in tick infestation was observed at the fifth count, and for adults, lower average counts were observed in all counts. The compounds did not interfere with the distribution of the ticks on the body of the dogs, as a similar percentage of ticks was found on the anterior half of the dogs (54.5% for the control group and 56.2% for the treated group). The biological and reproductive parameters of the ticks were not affected by the repellents. This study highlights for the first time the potential use of a novel allomone (repellent)-based formulation for reduction of tick infestation on susceptible dogs.
-
identification of non host semiochemicals for the brown dog tick rhipicephalus sanguineus sensu lato acari ixodidae from tick resistant beagles canis lupus familiaris
Ticks and Tick-borne Diseases, 2015Co-Authors: Lígia Miranda Ferreira Borges, Jaires Gomes De Oliveira Filho, Lorena Lopes Ferreira, J. A. Pickett, Carla Cristina Braz Louly, Michael Alexander BirkettAbstract:Studies have shown that the brown dog tick, Rhipicephalus sanguineus sensu lato, when fed on the beagle breed of dog, Canis lupus familiaris, development negatively affected in comparison with tick development after feeding on the English cocker Spaniel breed. Thus leading to the suggestion that beagle dogs are be tick-resistant dogs. Behavioural studies have demonstrated that more ticks are attracted by extracts from cocker Spaniels than from beagles and that the odour of beagles is a repellent. To test the hypothesis that resistant hosts produce repellent compounds, we undertook comparative chemical analysis on beagle odour and cocker Spaniel extracts using coupled high-resolution gas chromatography–mass spectrometry (GC–MS) and also used Petri-dish and olfactometer behavioural assays to assess the response of ticks to identified non-host compounds. The beagle odour extracts contained almost three times as many chemical compounds as cocker Spaniel samples. Several non-host compounds were identified, i.e. 2-hexanone, benzaldehyde, nonane, decane and undecane. In Petri-dish assays, 2-hexanone was repellent at 30 min at concentrations of 0.200 and 0.050 mg cm−2, whilst at 10 min, the 0.100 mg cm−2 concentration was repellent. Benzaldehyde repelled ticks at 30 min (0.200 mg cm−2) and at 5 min (0.050 mg cm−2). Undecane was repellent for R. sanguineus s.l. ticks for the first 5 min at the highest concentration tested. Nonane and decane did not show any significant repellency at any concentration or time evaluated. When 2-hexanone and benzaldehyde were combined, an increase in the repellency rate was observed, with activity comparable or better than N,N-diethyl-3-methylbenzamide (DEET). In olfactometer bioassays, a 1:1 mixture of 2-hexanone:benzaldehyde and DEET were repellent for R. sanguineus s.l. adults at the concentration of 0.200 mg cm−2. This study identified non-host semiochemicals that mediate avoidance of the beagle dog breed by R. sanguineus s.l. This finding may enable development of new approaches to control this tick.
Cathryn S. Mellersh - One of the best experts on this subject based on the ideXlab platform.
-
Prevalence and progression of pectinate ligament dysplasia in the Welsh springer Spaniel.
The Journal of small animal practice, 2016Co-Authors: James A. C. Oliver, Abel B. Ekiri, Cathryn S. MellershAbstract:OBJECTIVES To determine the prevalence of pectinate ligament dysplasia in a large group of Welsh springer Spaniels; to investigate associations between pectinate ligament dysplasia and age, sex and intraocular pressure and between intraocular pressure and age and sex; and to investigate progression of pectinate ligament dysplasia in individual dogs. METHODS In a prospective study, gonioscopy was performed in both eyes of 227 Welsh springer Spaniels and intraocular pressure measured by rebound tonometry. Eyes were classified as “unaffected” if 0% of the iridocorneal angle was affected with pectinate ligament dysplasia (grade 0), “mildly affected” if 90% was affected (grade 3). In a retrospective study, progression of pectinate ligament dysplasia over time was investigated for 65 dogs. RESULTS One hundred and thirty-nine of 227 dogs (61·2%) were affected by pectinate ligament dysplasia (grades 1 to 3) and 82/227 (36·2%) were moderately or severely affected. There was a significant association between pectinate ligament dysplasia and age. There were no associations between pectinate ligament dysplasia and intraocular pressure or pectinate ligament dysplasia and sex. Thirty-five of 65 dogs (53·8%) demonstrated progression of pectinate ligament dysplasia. CLINICAL SIGNIFICANCE Prevalence of pectinate ligament dysplasia was high despite widespread screening and selection against the condition. Our data indicate that gonioscopic features of pectinate ligament dysplasia can progress in the Welsh springer Spaniel. Dogs deemed unaffected at an early age may subsequently be diagnosed with pectinate ligament dysplasia.
-
An Intronic SINE insertion in FAM161A that causes exon-skipping is associated with progressive retinal atrophy in Tibetan Spaniels and Tibetan Terriers.
PloS one, 2014Co-Authors: Louise M. Downs, Cathryn S. MellershAbstract:Progressive retinal atrophy (PRA) in dogs is characterised by the degeneration of the photoreceptor cells of the retina, resulting in vision loss and eventually complete blindness. The condition affects more than 100 dog breeds and is known to be genetically heterogeneous between breeds. Around 19 mutations have now been identified that are associated with PRA in around 49 breeds, but for the majority of breeds the mutation(s) responsible have yet to be identified. Using genome-wide association with 22 Tibetan Spaniel PRA cases and 10 controls, we identified a novel PRA locus, PRA3, on CFA10 (praw = 2.01×10−5, pgenome = 0.014), where a 3.8 Mb region was homozygous within 12 cases. Using targeted next generation sequencing, a short interspersed nuclear element insertion was identified near a splice acceptor site in an intron of a provocative gene, FAM161A. Analysis of mRNA from an affected dog revealed that the SINE causes exon skipping, resulting in a frame shift, leading to a downstream premature termination codon and possibly a truncated protein product. This mutation segregates with the disease in 22 out of 35 cases tested (63%). Of the PRA controls, none are homozygous for the mutation, 15% carry the mutation and 85% are homozygous wildtype. This mutation was also identified in Tibetan Terriers, although our results indicate that PRA is genetically heterogeneous in both Tibetan Spaniels and Tibetan Terriers.
-
MHC class II association study in eight breeds of dog with hypoadrenocorticism
Immunogenetics, 2013Co-Authors: Jonathan Massey, Brian Catchpole, Alisdair Boag, Andrea D. Short, Rachel A. Scholey, Paula S. Henthorn, Meryl P. Littman, Eystein Husebye, Niels Pedersen, Cathryn S. MellershAbstract:Canine hypoadrenocorticism is an endocrine disorder characterised by inadequate secretion of steroid hormones from the adrenal glands. Pathology results from immune-mediated destruction of the adrenal cortex, which is similar to that seen in the human Addison’s disease. Both the canine and human diseases have similar clinical presentation, with the diagnosis based on performing a dynamic adrenocorticotropic hormone stimulation test. MHC class II has previously been associated with the human and canine diseases. In the current study, we conducted an MHC class II association study in eight breeds of dog with diagnoses of hypoadrenocorticism. We demonstrated significant differences in dog leukocyte antigen (DLA) haplotype frequencies in six of these breeds: Cocker Spaniel, Springer Spaniel, Labrador, West Highland white terrier (WHWT), Bearded collie, and Standard poodle. In the Springer Spaniel, the DLA-DRB1*015:01--DQA1*006:01--DQB1*023:01 haplotype was significantly associated with disease risk ( p = 0.014, odds ratio (OR) = 5.14) and showed a similar trend in the Cocker Spaniel. This haplotype is related to one associated with hypoadrenocorticism in the Nova Scotia duck tolling retriever. Similar haplotypes shared between breeds were demonstrated, with DLA-DRB1*001:01--DQA1*001:01--DQB1*002:01 more prevalent in both affected Labrador ( p = 0.0002, OR = 3.06) and WHWT ( p = 0.01, OR = 2.11). Other haplotypes that have not previously been associated with the disease were identified. The inter-breed differences in DLA haplotypes associated with susceptibility to canine hypoadrenocorticism could represent divergent aetiologies. This could have implications for clinical diagnosis and future comparative studies. Alternatively, it may suggest that the gene of interest is closely linked to the MHC.
Jaires Gomes De Oliveira Filho - One of the best experts on this subject based on the ideXlab platform.
-
brown dog tick rhipicephalus sanguineus sensu lato infestation of susceptible dog hosts is reduced by slow release of semiochemicals from a less susceptible host
Ticks and Tick-borne Diseases, 2017Co-Authors: Jaires Gomes De Oliveira Filho, Lorena Lopes Ferreira, J. A. Pickett, Michael Alexander Birkett, Andre Lucio Franceschini Sarria, Gabriel Moura Mascarin, Adalberto Perez A De Leon, Lígia Miranda Ferreira BorgesAbstract:Domestic dog breeds are hosts for the brown dog tick, Rhipicephalus sanguineus sensu lato, but infestation levels vary among breeds. Beagles are less susceptible to tick infestations than English cocker Spaniels due to enhanced production of 2-hexanone and benzaldehyde that act as volatile tick repellents. We report the use of prototype slow-release formulations of these compounds to reduce the burden of R. sanguineus s. l. on English cocker Spaniel dogs. Twelve dogs were randomly assigned to two groups with six dogs each. The treated group received collars with slow-release formulations of the compounds attached, while the control group received collars with clean formulations attached. Five environmental infestations were performed, with the number of ticks (at all stages) on the dogs being counted twice a day for 45 days. The counts on the number of tick stages found per dog were individually fitted to linear mixed effects models with repeated measures and normal distribution for errors. The mean tick infestation in the treated group was significantly lower than in the control group. For larvae and nymphs, a decrease in tick infestation was observed at the fifth count, and for adults, lower average counts were observed in all counts. The compounds did not interfere with the distribution of the ticks on the body of the dogs, as a similar percentage of ticks was found on the anterior half of the dogs (54.5% for the control group and 56.2% for the treated group). The biological and reproductive parameters of the ticks were not affected by the repellents. This study highlights for the first time the potential use of a novel allomone (repellent)-based formulation for reduction of tick infestation on susceptible dogs.
-
identification of non host semiochemicals for the brown dog tick rhipicephalus sanguineus sensu lato acari ixodidae from tick resistant beagles canis lupus familiaris
Ticks and Tick-borne Diseases, 2015Co-Authors: Lígia Miranda Ferreira Borges, Jaires Gomes De Oliveira Filho, Lorena Lopes Ferreira, J. A. Pickett, Carla Cristina Braz Louly, Michael Alexander BirkettAbstract:Studies have shown that the brown dog tick, Rhipicephalus sanguineus sensu lato, when fed on the beagle breed of dog, Canis lupus familiaris, development negatively affected in comparison with tick development after feeding on the English cocker Spaniel breed. Thus leading to the suggestion that beagle dogs are be tick-resistant dogs. Behavioural studies have demonstrated that more ticks are attracted by extracts from cocker Spaniels than from beagles and that the odour of beagles is a repellent. To test the hypothesis that resistant hosts produce repellent compounds, we undertook comparative chemical analysis on beagle odour and cocker Spaniel extracts using coupled high-resolution gas chromatography–mass spectrometry (GC–MS) and also used Petri-dish and olfactometer behavioural assays to assess the response of ticks to identified non-host compounds. The beagle odour extracts contained almost three times as many chemical compounds as cocker Spaniel samples. Several non-host compounds were identified, i.e. 2-hexanone, benzaldehyde, nonane, decane and undecane. In Petri-dish assays, 2-hexanone was repellent at 30 min at concentrations of 0.200 and 0.050 mg cm−2, whilst at 10 min, the 0.100 mg cm−2 concentration was repellent. Benzaldehyde repelled ticks at 30 min (0.200 mg cm−2) and at 5 min (0.050 mg cm−2). Undecane was repellent for R. sanguineus s.l. ticks for the first 5 min at the highest concentration tested. Nonane and decane did not show any significant repellency at any concentration or time evaluated. When 2-hexanone and benzaldehyde were combined, an increase in the repellency rate was observed, with activity comparable or better than N,N-diethyl-3-methylbenzamide (DEET). In olfactometer bioassays, a 1:1 mixture of 2-hexanone:benzaldehyde and DEET were repellent for R. sanguineus s.l. adults at the concentration of 0.200 mg cm−2. This study identified non-host semiochemicals that mediate avoidance of the beagle dog breed by R. sanguineus s.l. This finding may enable development of new approaches to control this tick.
