Article

Clinical characteristics of microphthalmia with colobomas of the Australian Shepherd Dog

Authors:
To read the full-text of this research, you can request a copy directly from the authors.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... In breeds such as the Australian Shepherd Dog (16,17), Chow Chow (18), Dobermann Pinscher (19)(20)(21) and Akita (6), retinal dysplasias have been observed together with other severe ocular defects (such as microphthalmia and congenital cataract). There are also cases seen occurring together with skeletal chondrodysplasia in Labrador Retrievers (22) and Samoyeds (23). ...
... Geographic form is seen in English Springer Spaniels, Cavalier King Charles Spaniels and Golden Retrievers, while complete retinal dysplasia developing with retinal Retinal dysplasias have been reported to occur together with intraocular defects in breeds such as Akita (6), Australian Shepherd Dog (16,17), Chow Chow (18) and Dobermann Pinscher (19)(20)(21); and together with skeletal chondrodysplasia in Labrador Retrievers (22) and Samoyeds (23). While these disorders were not encountered in our study groups, neither was a report found on genetic retinal diseases in the two dog breeds constituting our study. ...
Article
Full-text available
In this study, normal fundoscopic variations and genetic retinal diseases of Turkish sheepdogs (Akbash and Kangal) have been assessed. According to comparative results obtained from 35 Akbash and 35 Kangal dogs, it was determined that blue tapetal regions were present at a rate of 65% in the Akbash breed and yellow-green tapetal regions were present at a rate of 60% in the Kangal breed. No fundoscopic or clinical sign suggesting albunism, subalbunism or progressive retinal atrophy was observed in either group. However, multifocal retina dysplasia was seen at a rate of 17.1% in the Akbash breed and 5.4% in the Kangal breed. The fact that all of these lesions, which presented typical fundoscopic appearance, were seen in females was interpreted as coincidental. It was of particular interest that these retinal dysplasias, which did not disrupt sight, occurred 3 times more in the Akbash breed compared to the Kangal breed.
... Such conditions include inherited retinal dysplasia and PHPV in 15 vitreoretinal dysplasia in the Bedlington terrier, 16 retinal dysplasia with microphthalmos in the Sealyham terrier, 17 retinal dysplasia with cataracts and persistent pupillary membranes in the Chow Chow, 18 and merle ocular dysgenesis in the Australian Shepherd and related breeds. 19 The impact of ocular changes associated with OSD is variable, ranging from absence of clinical signs in mild cases to vision loss in severe cases. Ocular discomfort could also occur with OSD, albeit not observed in the present study, as cataracts and retinal separation can result in chronic uveitis and secondary glaucoma, necessitating removal of the eye (enucleation) if it becomes painful and blind. ...
Article
Objective: To describe the clinical features and diagnostic findings of Labrador Retrievers with oculo-skeletal dysplasia (OSD). Animal studied: Five privately owned dogs. Procedures: Medical records of dogs diagnosed with OSD from 2008 through 2018 were reviewed. Patients were excluded if lacking disease confirmation through genetic testing (Optigen RD/OSD). Information collected included signalment, physical and ophthalmic examination findings, results of ocular ultrasound and electroretinogram, and digital radiographs of forelimbs and pelvis. Results: All five dogs were Labrador Retrievers, confirmed to be homozygote for the OSD mutation. The main physical abnormalities were vision deficits (5 dogs), short-limbed dwarfism (5), carpal valgus (4), and color dilution alopecia (4). The main ophthalmic anomalies were cataracts (10 eyes), vitreous syneresis (10), retinal separation (6), persistent hyperplastic primary vitreous (2), lens coloboma (2), microphakia (2), and persistent tunica vasculosa lentis (1). Ocular ultrasound and electroretinogram confirmed the diagnoses of retinal separations and persistent hyperplastic primary vitreous. Radiographic changes included shortening of ulna and curved radius (5 dogs), elbow incongruity and osteoarthritis (4 dogs), hip dysplasia (3), and coxofemoral osteoarthritis (2). Available follow-up information (2 dogs) showed progression of cataract from incipient to mature in one dog, necessitating cataract surgery, and progression of cataract and lameness in another dog. Conclusions: The clinical findings of OSD are described in five Labrador Retrievers. DNA testing is critical to diagnose OSD and help eradicate this condition from the breed. Progression of cataracts and osteoarthritis in dogs with OSD warrants yearly monitoring.
... Animals with this form of deafness may, however, have other abnormalities making up a more generalized syndrome seen with particular coat color patterns. For example, dogs homozygous for the merle gene may be deaf and have microphthalmia with other associated ocular conditions and be sterile (26,27). ...
... 21 Canine merle coat coloration has also been associated with ocular defects including coloboma, and microphthalmia. 22,23 However, there have been indications in horses about a dissociation of the PMEL17 and MCOA mutations by recombination: for example, MCOA-like abnormalities have not been seen in some PMEL17 mutant horses, including some silvercolored Icelandic ponies 1,2,5,6,10 and possibly our case 3, and a few nonsilver dapple horses have expressed the MCOA phenotype. 1,2,5,6,10 The prevalence of MCOA in purebred and crossbred Rocky Mountain and Kentucky Mountain horses has been estimated to be ~50% of their populations. ...
Article
To describe the clinical phenotype and genetics of equine Multiple Congenital Ocular Anomalies (MCOA) syndrome in PMEL17 (Silver) mutant ponies. Five presumably unrelated ponies. The ponies were examined under field conditions in their barn by slit lamp biomicroscopy, indirect ophthalmoscopy, and applanation tonometry. Blood was collected and genomic DNA extracted for MCOA genotyping using the PMEL17ex11 marker. One pony solely presented with temporal ciliary body cysts, suggestive of the less severe Cyst phenotype of MCOA; the animal was heterozygous at the MCOA locus. Multiple bilateral anterior segment anomalies were identified in four ponies, consistent with the more severe MCOA phenotype characterized by cornea globosa, iris hypoplasia, encircling granula iridica along the pupillary ruff, and cataracts. These animals were homozygous for the mutant MCOA allele. Four of the ponies had a silver dapple or chocolate coat color with white or flaxen manes and tails. Silver dappling was masked by the palomino coloring of a 5th pony that was homozygous at the MCOA locus. The MCOA syndrome can be seen in ponies. The results of both clinical evaluation and genotyping resembled the previously described MCOA of both Rocky Mountain and Kentucky Mountain Saddle horses.
... Also, merle dogs exhibit greater frequencies of ocular abnormalities than do non-merle dogs. These include increased ocular pressure, ametropic eyes, microphthalmia, and colobomas ( Sorsby and Davey, 1954; Gelatt and McGill, 1973; Dausch et al. 1977). Skeletal defects and sterility have also been reported in double merle dogs (Sponenburg and Bowling, 1985; Treu et al., 1976). ...
Chapter
Full-text available
Short interspersed elements (SINEs) are mobile elements that contribute to genomic diversity through the addition of genetic material. Recent genomic analyses have vastly augmented our knowledge of both human- and canine-specific SINEs. SINEC_Cf is a major SINE of the canid family that has undergone recent expansion and is thought to be present in half of all genes. To date, only three phenotypes of the domestic dog have been attributed to a SINE. One of these is merle, a coat pattern characterized by patches of full color on a diluted background and associated with ocular and auditory anomalies. A SINEC_Cf in the SILV gene causes merle patterning by altering the cDNA transcript and has unique characteristics that are likely responsible for the random nature of the phenotype.
... 7,8,43 In some forms, there may be other concurrent ocular developmental disorders such as persistent hyperplastic primary vitreous, 8,23 congenital cataracts, 12,20,37 microphthalmia, 12,21-23 or coloboma. 14,15,39 Syndromic forms have also been reported, with affected dogs having concurrent nonocular abnormalities such as dwarfism with skeletal dysplasia, as occurs in ocular skeletal dysplasia (OSD). [31][32][33]44 OSD has been studied in detail in the labrador retriever and samoyed breeds in which it is termed dwarfism with retinal dysplasia (drd). ...
Article
Objective The purpose of this study was to investigate the inheritance and phenotype of retinal dysplasia (RD) in the American pit bull terrier.Animals StudiedA breeding colony established from a single female pure-bred American pit bull terrier dog with RD.ProceduresA female pure-bred American pit bull terrier with RD was donated to the Veterinary Hospital of Federal University of Paraná, Curitiba, Brazil. A breeding colony was established and the phenotype and inheritance of the condition investigated. Regular ophthalmic examinations and fundus photography were performed on three generations of offspring from the founder animal. Some animals were additionally studied by optical coherence tomography. Ocular histopathology was performed on some animals from the colony.ResultsFifty-seven offspring were produced in two generations from the affected founder female. Thirty-two were diagnosed with RD and showed a spectrum of severity of lesions including multifocal, and or geographic lesions and some developed retinal detachment. Histologic examination demonstrated retinal folds, rosettes, and areas of retinal detachment. The affected dogs were shorter in stature than the unaffected littermates. Breeding studies suggested the trait has an autosomal dominant mode of inheritance. DNA testing showed that the affected dogs were negative for the known gene mutations for canine dwarfism with RD.Conclusion This is a report of a novel inherited form of RD that affects American pit bull terriers.
... The ASD syndrome also has a relatively close resemblance to the defects observed in Small eye mice and rats [23]. Microphthalmia is well described in homozygous blue merle Australian Shepherd dogs [24]. It is hypothesized that horses homozygous for the Silver mutation have more severe symptoms of the ASD syndrome than hetero- zygotes [25]. ...
Article
Full-text available
The Silver coat color, also called Silver dapple, in the horse is characterized by dilution of the black pigment in the hair. This phenotype shows an autosomal dominant inheritance. The effect of the mutation is most visible in the long hairs of the mane and tail, which are diluted to a mixture of white and gray hairs. Herein we describe the identification of the responsible gene and a missense mutation associated with the Silver phenotype. Segregation data on the Silver locus (Z) were obtained within one half-sib family that consisted of a heterozygous Silver colored stallion with 34 offspring and their 29 non-Silver dams. We typed 41 genetic markers well spread over the horse genome, including one single microsatellite marker (TKY284) close to the candidate gene PMEL17 on horse chromosome 6 (ECA6q23). Significant linkage was found between the Silver phenotype and TKY284 (theta = 0, z = 9.0). DNA sequencing of PMEL17 in Silver and non-Silver horses revealed a missense mutation in exon 11 changing the second amino acid in the cytoplasmic region from arginine to cysteine (Arg618Cys). This mutation showed complete association with the Silver phenotype across multiple horse breeds, and was not found among non-Silver horses with one clear exception; a chestnut colored individual that had several Silver offspring when mated to different non-Silver stallions also carried the exon 11 mutation. In total, 64 Silver horses from six breeds and 85 non-Silver horses from 14 breeds were tested for the exon 11 mutation. One additional mutation located in intron 9, only 759 bases from the missense mutation, also showed complete association with the Silver phenotype. However, as one could expect to find several non-causative mutations completely associated with the Silver mutation, we argue that the missense mutation is more likely to be causative. The present study shows that PMEL17 causes the Silver coat color in the horse and enable genetic testing for this trait.
... Ezen felül a homozigóta merle, azaz két mutáns allélt hordozó cifra kutyáknál a látást vagy a hallást érintő rendellenességek -pl. süketség, microphthalmia -jelentősen gyakrabban fordulnak elő a nem-merle egyedekhez viszonyítva (8,19,20). ...
Article
Full-text available
Background: The merle colour in dogs (merle: blackbird) is caused by a retrotransposon insertion in the SILV gene, resulting in malfunction in the eumelanin producing pigment cells. In homozygous (MM) individuals congenital auditory and ophthalmologic disorders are common, therefore the mating of two heterozygous (Mm) dogs should be avoided, and is in fact forbidden in case of breeds having this trait. Some of the colours, however are fully characterised by pheomelanin pigment (e. g. cream, beige, fawn), which are not affected by the merle gene, making it impossible to recognize the heterozygous individuals based on their phenotype (hidden merles). Objectives: The author's aim was to test a fast, reliable and cost-efficient genetic method in the Mudi breed, because in this breed along with the merle colour, white and fawn colours can also be found-which increases the chance for hidden merle individuals. Materials and Methods: In their study the authors used 23 hair or buccal swab samples collected from Hungarian and foreign possible hidden merle Mudi dogs, then multiplied the exon 11 of the SILV gene with polymerase chain reaction (PCR) method from the purified DNA. Agarose gel electrophoresis was used to detect the PCR products (M and m alleles) and to separate them by size. The authors compared their genotype results with the dogs' phenotypic traits (colour of the eyes and the fur). Results and Discussion: According to practical observations blue or partial blue eyes are solely caused by the merle gene in the Mudi breed, this observation was confirmed by the authors' DNA test, so in these simple cases hidden merle dogs can be detected by their phenotype. However, eye colour is not always affected by the merle gene: in this research 4 of the 17 brown eyed dogs tested proved to be heterozygous Mm. This indicates that the genetic test is the only reliable way to identify hidden merle individuals, which is important to prevent puppies with decreased viability.
Article
Objective: Multiple ocular defects are common findings in homozygous merle dogs. Although a SINE-insertion causative for the merle phenotype has already been identified in the SILV gene on the canine chromosome 10, an association of this mutation with eye malformations has not been established yet. Material and methods: Four Old German Sheepdogs and four Australian Shepherds with the different types of the merle coat colours were genotyped for the SILV mutation to confirm the MM, Mm and mm genotypes. A sequence and haplotype analysis of SILV was performed. MITF that regulates SILV expression during embryogenesis was chosen as candidate being involved in the development of the ocular malformations. Flanking and intragenic markers were genotyped, and association analysis was performed. Results: All MM-dogs showed multiple ocular defects such as colobomata, microphthalmia, dyscoria and persistent pupillary membrane. No length difference in the SINE or polymorphisms in the exonic sequences between dogs with and without ophthalmological defects were detected. The SILV flanking markers showed complete co-segregation with the merle genotypes. We detected a significant association between MITF markers and ocular defects of the double merle-phenotypes. Conclusions: We could not detect mutations in the SILV gene to explain the double merle phenotype-associated eye malformations. The significant association of the MITF-linked markers may suggest that MITF could be involved in the development of the ocular defects in MMdogs. These results have to be scrutinized because only three MM-dogs were available and these results have to be confirmed using a larger data set. Clinical relevance: Our results indicate that mutations in the SILV gene may not be responsible for the development of the ocular defects often seen in double merle dogs but a possible involvement of the MITF gene has to be discussed. If the role of MITF for these eye anomalies can be clarified in a study comprising much more dogs the associated mutations in MITF may be identified. Thus it would be possible to prevent these ocular malformations through selective breeding.
Chapter
Full-text available
The interaction between the plant pathogenic bacterium Xanthomonas campestris pv. vesicatoria (Xcv)∈dexXanthomonas campestris pv. vesicatoria (Xcv) and its host plants pepper and tomato depends on a type III protein secretion system (T3SS)∈dextype III protein secretion system (T3SS) which translocates effector proteins into the plant cell. Recent studies revealed that HpaB and HpaC are two key players in the control of protein export from Xcv. First identified by their avirulence activity in resistant plants, genome sequencing projects allow now the identification of more effector proteins. However, their virulence functions in the host remain elusive. The effector AvrBs3 from Xcv induces a hypertrophy in susceptible plants. The virulence as well as the avirulence activity of AvrBs3 depends on its eukaryotic features, i.e., nuclear localization signals and an activation domain suggesting that the effector mimics a plant transcriptional regulator. Here, we present recent progress on the identification of potential virulence targets of AvrBs3 in the plant cell.
Article
Full-text available
Merle is a pattern of coloring observed in the coat of the domestic dog and is characterized by patches of diluted pigment. This trait is inherited in an autosomal, incompletely dominant fashion. Dogs heterozygous or homozygous for the merle locus exhibit a wide range of auditory and ophthalmologic abnormalities, which are similar to those observed for the human auditory-pigmentation disorder Waardenburg syndrome. Mutations in at least five genes have been identified as causative for Waardenburg syndrome; however, the genetic bases for all cases have not been determined. Linkage disequilibrium was identified for a microsatellite marker with the merle phenotype in the Shetland Sheepdog. The marker is located in a region of CFA10 that exhibits conservation of synteny with HSA12q13. This region of the human genome contains SILV, a gene important in mammalian pigmentation. Therefore, this gene was evaluated as a candidate for merle patterning. A short interspersed element insertion at the boundary of intron 10/exon 11 was found, and this insertion segregates with the merle phenotype in multiple breeds. Another finding was deletions within the oligo(dA)-rich tail of the short interspersed element. Such deletions permit normal pigmentation. These data show that SILV is responsible for merle patterning and is associated with impaired function of the auditory and ophthalmologic systems. Although the mutant phenotype of SILV in the human is unknown, these results make it an intriguing candidate gene for human auditory-pigmentation disorders.
Article
Full-text available
The role of animal models in our developing understanding of anterior segment dysgenesis is outlined. Research in avian models shows the importance of the neural crest in the development of the anterior segment and the failure of terms such as anterior segment cleavage adequately to describe the embryology of this area. Study of the anatomical differences between the anterior segment of the primate and that of the sub-primate mammal explains the differences seen in the dysplastic changes occurring in the iridocorneal angle in man and those occurring in sub-primate mammals such as the rabbit or the dog. Such work gives an improved understanding of congenital lesions seen ophthalmologically in man as well as those encountered in veterinary ophthalmology.
Article
To investigate disease in the fellow eye, and consider the relation to rhegmatogenous retinal detachment (RRD) in Shih-Tzus. The fellow eyes of 49 Shih-Tzus (27 male, 22 female; median age: 6.8 years) with unilateral RRD diagnosed by funduscopy or ultrasonography at Rakuno Gakuen University Teaching Animal Hospital were assessed in this study. Ophthalmic examinations (including menace response, pupillary light reflex, slit-lamp biomicroscopy, and funduscopy) were performed in the subjects. Electroretinography was performed in 12 eyes that developed retinal degeneration. Maximum follow-up period was 42 months. Cataracts and vitreous opacity were observed in 26 (53%) and 32 eyes (65%), respectively, by slit-lamp biomicroscopy. Retinal degeneration with various degrees of hyper-reflectivity of the tapetal fundus and/or attenuation of retinal vessels was observed in 35 eyes (71%) on funduscopy. A reduction of amplitude in rod, standard combined and 30 Hz flicker electroretinogram was detected in 5 (42%), 10 (83%), and 6 eyes (50%), respectively. During the follow-up period, RRD was detected in six eyes. Retinal degeneration was frequently detected by funduscopy and electroretinograms in the fellow eye in Shih-Tzus with RRD. In our subjects, vitreous degeneration was also observed frequently. It has been reported that peripheral retinal degeneration is one of the causes of RRD associated with vitreous degeneration in humans. We assume that primary retinal degeneration with secondary vitreous degeneration is one of the causes of RRD in Shih-Tzus.
Chapter
This chapter presents an overview of Merle ocular dysgenesis (MOD) that results from abnormal embryonic differentiation of tissues and may lead to multiple ocular abnormalities, including any combination of microphthalmos, microcornea, scleral staphyloma, persistent pupillary membranes (PPMs), heterochromia iris, iridal hypoplasia/coloboma, pseudopolycoria, iridocorneal angle dysplasia, lenticular coloboma/cataract/subluxation, choroidal hypoplasia, optic nerve coloboma, retinal dysplasia, and/or retinal detachment. Commonly affected breeds include the Australian Shepherd, (merled) Collies, Shetland Sheepdog, Harlequin Great Dane and (merled) Long-Haired Dachshund. The diagnosis of MOD is made on the basis of a combination of signalment and clinical findings. Surgical intervention in order to address scleral, lenticular, and/or retinal pathology may also be indicated in select cases. Selective breeding reduces the incidence and severity of disease.
Chapter
Full-text available
In combination with goats, sheep represent the two most numerous agricultural species for which no cultural or ethical restrictions apply in their use as a source for milk, fibre and red meat. Particularly, in the developing world these species often represent the sole asset base for small-holder livestock farmers. Despite their global significance, genomic tools and approaches in disease resistance have lagged behind the efforts in the economically more influential beef and dairy cattle industries. In particular, infectious diseases have a significant economic impact on livestock production systems worldwide. The most frequently investigated diseases in sheep have focused on the economically important burdens including gastrointestinal nematodes, dermatophilosis, footrot, myiases and fasciolosis. In this study we describe the use of Indonesian Thin Tail sheep (ITT) as a resource which has been shown to have innate and acquired resistance to tropical fasciolosis (Fasciola gigantica∈dexFasciola gigantica). Using the contrast between the resistant ITT and the highly susceptible Merino in a combined functional and comparative genomics approach, we have identified putative QTL (quantitative trait loci) for an extensive panel of parasite and immune response phenotypes and putative resistance pathways and effector molecules. On refinement of candidate gene analyses and effector mechanisms we propose to map these in the economically important target species, namely cattle and buffalo. In addition we exploit the relative susceptibility of ITT sheep to temperate fasciolosis (Fasciola hepatica∈dexFasciola hepatica) to contrast parasite–host interactions and identify parasite immune evasion strategies to boost the discovery of new vaccine candidates and effector pathways, which may be amenable to exogenous control. The study highlights the power and utility of direct gene discovery in ruminant model systems. To overcome the shortage of genomic tools required for such investigations, we have drawn on the development of integrated comparative maps and alignment to the genome information–rich species such as human, murine and recently cattle. Similarly the use of bovine transcriptome tools have shown cross utility in sheep. The only species-specific requirement is the development of genome-wide high resolution SNP mapping tools which are now under development.
Chapter
Full-text available
Plants and animals trigger an innate immune response upon perception of pathogen-associated molecular patterns (PAMPs) such as flagellin. In Arabidopsis, flagellin perception elevates resistance to Pseudomonas syringae pv. tomato DC3000 (Pst DC3000), although the molecular mechanisms involved remain elusive. A flagellin-derived peptide transiently enhances the accumulation of a plant microRNA that directs degradation of mRNA for TIR1, an F-box auxin receptor. The resulting repression of auxin signaling effectively restricts Pst DC3000 growth, implicating this previously unsuspected miRNA-mediated switch in bacterial disease resistance. These data suggest that elevation of auxin levels constitute a bacterial pathogenicity strategy that is suppressed during the innate immune response to PAMPs. In a separate work, we showed that DELLA proteins, which are normally associated with gibberellin responses, play a role in the balance between salicylic acid and jasmonic acid–mediated defense signaling pathways. DELLA loss-of-function mutants show reduced growth inhibition in response to flg22, enhanced susceptibility to necrotrophic pathogens, and enhanced resistance to Pst DC3000.
Chapter
Full-text available
The use of genetics to enhance immune response and microbial resistance in poultry is an environmentally sound approach to incorporate into comprehensive health programs. Many research strategies can be used to investigate the relationship of host genetics with immune response and disease resistance. Gene discovery to enhance poultry health and food safety should build upon well-defined genetic populations, cell lines, gene identification, genome maps, comparative genomics, and analysis of gene expression. Because each investigative approach has its own shortfalls, the strongest level of confidence comes from the convergence of evidence from an integrated approach of several independent experimental designs, such as whole-genome scans, candidate gene analyses, and functional genomics studies, all supporting the relationship of a specific gene with a resistance or immunity trait. Defining the causal genes, including genomic location and organization, epistatic and pleiotropic effects, and the encoded protein function, opens the door for genetic selection to improve health and also for enhancement of vaccine efficacy and innate immunity. This chapter reviews the rationale and strategies for uncovering genetic resistance to food-safety pathogens in poultry and summarizes successes in elucidating the genetic control of host resistance to Salmonella.
Article
Zur Untersuchung des Merlesyndroms (unvollkommene dominante Depigmentierungsanomalie) wurde unter identischen Bedingungen eine Teckelkolonie von 44 Tieren gehalten und gezüchtet. In dieser Arbeit wird vornehmlich über die Veränderung der Augen berichtet. Schwere Augenmißbildungen zeigten sich einoder beidseitig bei 11 Tigerteckeln mit einem Aufhellungsgrad der Körperoberfläche von 50 % und mehr (homozygote Weißtiger, MM). Die Mißbildungen bestanden in Mikrophthalmus und Mikrokornea, Mikrokorie und Korektopie, Katarakten und Kolobomen, vereinzelt auch rudimentären Linsen und Ektasien der Episkleralgefäße. In heterozygoten Tigerteckeln (Mm) mit einem Weißanteil des Integuments unter 50 % kamen — ebenso wie in Weißtigern — Iris bicolor und Pigmentarmut der Regenbogenhaut, Fehlen des Tapetum lucidum, Retina-Pigmentarmut, Papillenanomalien und Ektasien episkleraler Gefäße zur Beobachtung, wenngleich nicht bei allen Tieren. Diese Befunde wurden als Gen-Dosiswirkungen des unvollkommen dominanten Merlefaktors M, eines in mehreren Hunderassen zur Erzeugung typischer „dHarlekin-Sprenkelung“ benutzten Depigmentierungsgens, interpretiert. Abgesehen von vereinzelten Ektasien episkleraler Gefäße, konnten bei 13 homozygot einfarbigen, gut pigmentierten, mit dem Merlefaktor nicht behafteten Kontrolltieren keinerlei Normabweichungen registriert werden. Die vergleichend-medizinische Bedeutung, insbesondere für das Klein-Waardenburg-Syndrom, sowie die Wichtigkeit von Maß-nahmen des Tierschutzes zur Verhinderung der Ausbreitung des Merle-Syndroms werden diskutiert.
Chapter
Full-text available
The basidiomycete fungus Ustilago maydis∈dexUstilago maydis establishes a biotrophic relationship with its host plant maize which is maintained throughout disease development. Recent insights from the genome sequence have revealed that this interaction is largely governed by a set of novel secreted proteins that are only found in U. maydis. Many of the respective genes are clustered and appear co-regulated during late stages of pathogenesis. Mutants in most of these gene clusters arrest development at distinct stages, suggesting that the secreted proteins fulfill discrete functions in the interaction with the host. One of the cluster mutants, however, displays increased virulence suggesting that it is not in the interest of U. maydis to use its full potential as a pathogen. In this chapter we will review these findings and place them in perspective for a comprehensive understanding of biotrophy.
Chapter
Congenital ocular anomalies in canines are detectable at birth, or occur prior to cessation of ocular development in those species in which development continues for a short time after birth. Many of these reflect defective cell signaling that normally triggers the complicated interplay of tissue induction and regression required for normal organogenesis. Defective organogenesis can be divided into two broad groups. First, those disorders that develop early on as a result of defects in the formation of the optic vesicle or its subsequent involution to form the optic cup. Most of these defects reflect failures of neurectoderm, except defects in lenticular development such as aphakia and microphakia which are surface ectodermal anomalies. Second, later defects in maturation of neurectoderm and periocular mesenchyme that occur in the second half of gestation cause anomalies that are generally identified as more isolated defects in globes of normal size and generally normal architecture.
Chapter
One evolutionary theory of why some pathogens kill their host (i.e. are virulent) is that they need to extract host resources in order to transmit to new hosts. We have tested this theory in malaria and find it to be a likely explanation for the maintenance of this parasite’s virulence in nature.
Chapter
The domestic cat is one of man’s most beloved species, living in households as companions, working on farms for vermin control, and co-habitating in urban environments as semi-feral occupants. Advances in veterinary medicine provide health care and diagnostics for the domestic cat on a comparable level to humans. Fancy breeds result in the selection of aesthetically pleasing traits and, sometimes, undesired health conditions, both of which can be useful as models for human development, physiology, and health. Reproductive techniques have allowed research in the cat to expand into cloning studies and genomic tools are assisting the cat with the same research scrutiny as the more prominent research animal models, rodents and humans. This chapter explores the genetic mysteries of the cat and provides a current state of the union for cat genetic research. Cat\ ’kat\ – a long domesticated carnivorous mammal that is usually regarded as a distinct species though probably ultimately derived by selection, among the hybrid progeny of several small Old World wildcats that occurs in several varieties distinguished chiefly by length of coat body and presence or absence of tail and that makes the pet valuable in controlling rodents and other small vermin but tends to revert to a feral state if not housed and cared for (Webster 3rd New International Dictionary).
Article
Eleven cases of congenital ocular defects were found in the screening of 144 Cavalier King Charles Spaniels in Sweden. Mainly posterior lenticonus, cataracts and microphthalmia were observed in the affected dogs, most of which were interrelated. Pathology was obtained from one of the cases demonstrating bilateral posterior lens capsule rupture with an unusual cellular reaction of the exposed lens material.
Article
Es werden die klinischen, autoptischen und histologischen Befunde eines Falles von komplexen Kolobomen an Iris, Ziliarkörper und vorderer Retina bei einem Beagle-Hund beschrieben. Auf einer Seite besteht nur ein rudimentäres Kolobom der Netzhaut-Ora. Auf der Gegenseite sind die vordere Uvea und Retina erheblich dysplastisch. Proliferationen von Pigment- und Ziliar-epithel reichen bis zum lokal kataraktösen Linsenäquator. Kammerbucht und Ziliarspalte sind atypisch. Der Ziliarmuskel ist verkürzt, der M. dilatator pupillae fehlt, der Sphinkter ist fehlgebildet. Das vordere retinale Pigment-epithel fehlt, die degenerierte Retina reicht bis auf den vorderen Ziliarkörper. Gleichzeitig bestehen kolobomunabhängige Retinafalten und atypische Pigmentgranula im Pigmentepithel der Übergangszone des Tapetum.
Book
Veterinary Ocular Pathology: A Comparative Review links the clinical features of ocular disease with gross and microscopic pathology to demonstrate the essential features observable during diagnosis. It is designed to be kept next to the microscope as an invaluable guide to accurate diagnosis in ocular pathology. The book presents a wide range of images of the highest quality. A unique and distinctive feature is the juxtaposition of clinical and pathological images while offering detailed enumeration of the diagnostic features. Expert comparative comments by Dr Daniel Albert and contextual information on relative incidence are provided throughout. The authors address spontaneous disease of the eye in all animal species, with a particular emphasis on companion species. In addition, specific, common or interesting conditions of exotic species are included. A convenient, comprehensive and easy-to-use reference for veterinary pathologists, veterinary ophthalmologists, students and comparative vision scientists. The first text devoted to the pathology of spontaneous diseases of the eyes and periocular tissues of domestic animal species Exceptionally high quality illustrations are presented throughout, demonstrating clinical features, gross pathology and histopathology Written by pathologists and clinicians Includes a chapter devoted to the pathology of conditions associated with glaucoma in domestic animals.
Article
Full-text available
Clinical case records of animals presented to the State Veterinary Hospital and the University of Maiduguri Veterinary Teaching Hospital (Unimaid VTH) Nigeria, between May 2004 to May, 2007 were studied for cases of dermoid and/or micropthalmia. Four (0.32%) cases of corneal dermoid and micropthalmia were found at the State Veterinary Hospital. Three of the cases were ovine species and one was bovine. No case of either corneal dermoid or micropthalmia was found in the Unimaid VTH during the period of study. The treatment procedures for the cases recorded are discussed and the need for further studies to determine the prevalence, specie and breed distribution is emphasized.
Article
Chapter
The microphthalmic eye appears grossly smaller than normal. The palpebral fissure will usually be proportionally reduced in size (Fig. 102). In addition, the globe may be deeply recessed into the orbit, making examination difficult. Microphthalmia is often accompanied by corneal and/or lens opacities, which may be grossly apparent.
Chapter
Full-text available
Oomycete plant pathogens such as Phytophthora species and downy mildews cause destructive diseases in an enormous variety of crop plant species as well as forests and native ecosystems. These pathogens are most closely related to algae in the kingdom Stramenopiles, and hence have evolved plant pathogenicity independently of other plant pathogens such as fungi. We have used bioinformatic analysis of genome sequences and EST collections, together with functional genomics to identify plant and pathogen genes that may be key players in the interaction between the soybean pathogen Phytophthora sojae and its host. In P. sojae, we have identified many rapidly diversifying gene families that encode potential pathogenicity factors including protein toxins, and a class of proteins (avirulence or effector proteins) that appear to have the ability to penetrate plant cells. Transcriptomic analysis of quantitative or multigenic resistance against P. sojae in soybean has revealed that there are widespread adjustments in host gene expression in response to infection, and that some responses are unique to particular resistant cultivars. These observations lay the foundation for dissecting the interplay between pathogen and host genes during infection at a whole-genome level.
ResearchGate has not been able to resolve any references for this publication.