Colour Dilution Alopecia in Doberman Pinschers with Blue or Fawn Coat Colours: A Study on the Incidence and Histopathology of this Disorder

Abstract— A population of 57 blue or fawn Doberman Pinschers was studied to determine the incidence of colour dilution alopecia in this breed. Forty two dogs had hair loss, typical of colour dilution alopecia. The diagnosis was confirmed in 11 dogs by skin biopsy and in 6 dogs by light microscopic examination of plucked hairs. Key diagnostic features included large macromelanosomes in the hair shafts, free clumps of melanin in the lumens of hair follicles, and numerous perifollicular melanophages. An hypothesis on the pathogenesis of colour dilution alopecia is proposed. Résumé— Une population de 57 Pinschers à robe bleue ou feu a étéétudiée pour déterminer la fréquence de l'alopécie par dilution de couleur dans cette race. 42 chiens ont présenté une perte de poils caractéristique de l'alopécie par dilution de couleur. Le diagnostic a été confirmé chez 11 chiens par biopsie cutanée et chez 6 chiens par l'examen au microscope optique des poils épilés. Les caractéristiques diagnostiques comprennent la présence de grands macromélanosomes dans les racines des poils, de manchons libres de mélanine dans la lumière des follicules pileux et de nombreux mélanophages périfolliculaires. Une hyhpothèse sur la pathogénie de l'alopécie par dilution de couleur est proposée. Zusammenfassung— Untersucht wurden 57 blaue und rehfarbene Dobermänner, um das Vorkommen der Farbmutanten-Alopezie bei dieser Rasse feststellen zu können. 42 dieser Hunde zeigten den für diese Erkrankung typischen Haarausfall. Bei 11 Patienten wurde die Diagnose durch Hautbiopsie und bei 6 durch lichtmikroskopische Untersuchung von ausgezupften Haaren gesichert. Die charakteristichen Bilder waren Makromelanosome in den Haarschäften, freies zusammengeballtes Melanin im Lumen der Haarfollikel und zahlreiche perifollikuläre Melanophagen. Eine Hypothese für die Pathogenese dieser Erkrankung wird aufgestellt. Resumen Se estudió una población de 57 perros de raza Doberman y color gris o azul para determinar la incidencia de la alopecia por dilución de color en esta raza. 42 perros presentaban pérdidas de pelo típicas de la alopecia por dilución de color. En 11 perros el diagnóstico se confirmó mediante biopsia y en 6 mediante examen microscópico del pelo. Las características diagnósticas de este proceso consistían en la presencia de macromelanosomas en las vainas de los pelos, y en la presencia de acúmulos de melanina libre en el interior de los folículos pilosos y de melanófagos perifoliculares. Se propone una hipótesis sobre la patogenia de esta enfermedad.     

Improved immunobinding test using monoclonal antibodies for detection of Mycoplasma bovis in milk

The aim of this study was to evaluate an improved immunobinding test (IBT) using monoclonal antibodies to identify Mycoplasma bovis in naturally infected milk. The IBT and the improved IBT were highly specific and had an immunologic sensitivity of 5 × 10³ colony-forming units per milliliter. The results for the 2 methods agreed in the 130 milk samples tested. However, the IBT required 158 min, whereas the improved IBT required only 110 min. In addition, the improved IBT used smaller quantities of antibodies and conjugates.     

Genetic relationship of Mediterranean mandarins (Citrus deliciosa Tenore) using RAPD markers

Summary Random amplified polymorphic DNA (RAPD) analysis was carried out to evaluate polymorphism and genetic similarity between 39 Mediterranean mandarin genotypes. One hundred eleven amplification products were identified using 21 random primers. An average of 2.2 RAPD markers was obtained for each primer, corresponding to 42% of the amplification products. Genotype-specific RAPD markers were also found, mainly in known hybrids. UPGMA cluster analysis revealed the low level of genetic variation between accessions of Mediterranean mandarins, whereas their hybrids with other Citrus species showed greater genetic dissimilarity. Twenty accessions yielded very similar patterns, suggesting either that they could be a single clone, or that the technique was not able to detect genomic variation. However, for the other specimens genetic polymorphism can easily be detected by RAPD, although the genetic variation between accessions was quite low. The large number of hybrids and the low polymorphism between accessions support the hypothesis that Mediterranean mandarins are all true hybrid of Common mandarins (Citrus reticulata Blanco).     

Large yield differences between reciprocal families of Solanum tuberosum

Summary A number of reports have indicated differences in reciprocal families of Solanum tuberosum when intergroup hybrids were studied. Questions have been raised concerning the potential magnitude, frequency, and genetic basis for such differences. In this study, exact reciprocal crosses were made using parents characterized by different maturities and having different cytoplasmic sources within Solanum tuberosum in order to substantiate previous claims of reciprocal differences and to clarify the nature of such differences.Field trials revealed reciprocal differences which were large and highly significant. Reciprocal yield differences of up to 115% were observed when parents of opposite maturities were used. In seven crosses, the higher-yielding reciprocal always had the higher-yielding parent as the maternal parent. Significant reciprocal differences for flowering and vine maturity were also observed between some families. The F₂ populations were generated for one set of reciprocals and the reciprocal differences in the F₂ generation seemed to be substantially reduced relative to the F₁ generation.It is concluded that the occurrence of large reciprocal differences seems to depend more upon having parents of opposite maturity than upon the taxonomic origin of the parent's cytoplasm. This, in conjunction with the reduced F₂ reciprocal differences, suggests that observed differences may be due to very persistent maternal effects or a type of dauermodification, rather than true cytoplasmic inheritance.Cooperative Investigation of U.S. Department of Agriculture, Science and Education Administration. Agricultural Research and the Wisconsin Agricultural Experiment Station.     

Assignment of Endosperm Balance Numbers to the tuber-bearing Solanums and their close non-tuber-bearing relatives

The Endosperm Balance Number (EBN) of over 80 species and subspecies of the tuber-bearing Solanums and their close non-tuber-bearing relatives representing 13 taxonomic series has been determined, with no species assigned to more than one EBN level. Among North American species, most diploids are 1EBN, most tetraploids are 2EBN and all hexaploids are 4EBN; however, among South American species most diploids are 2EBN, most tetraploids are 4EBN and again all hexaploids are 4EBN. Thus species may be isolated from others of the same ploidy level by EBN differences, e.g., 4×(2EBN) from 4×(4EBN), while other species differing in ploidy but having the same EBN may be intercrossed, e.g., 4×(2EBN) and 2×(2EBN). Chromosome doubling or 2n gametes can be used to make a lower EBN species compatible with a higher EBN species. These findings also explain the major crossing difficulties previously inherent in the use of North American species in potato improvement. They also have direct implications for potato improvement, barring the occurrence of other incompatibility barriers. Any 4×(4EBN) cultivar is endosperm compatible and thus will cross with 4×(4EBN) and 6×(4EBN) species. The 2×(2EBN) haploids of 4×(4EBN) cultivars likewise will hybridize with 2×(2EBN) and 4×(4EBN) species. All 2×(1EBN) species are crossable with 2×(2EBN) haploids through 2n gametes or chromosome doubling.Cooperative investigation of the U.S. Department of Agriculture, Agriculture Research Service, and the Wisconsin Experiment Station.     

Determining tomato fruit maturity with nondestructive in vivo nuclear magnetic resonance imaging

Nuclear magnetic resonance (NMR) images were taken of freshly harvested fruit (Lycopersicon esculentum cv. Castlemart). Measurements were also made of the stage of repeness, rate of carbon dioxide and ethylene production, lycopene and chlorophyll content, density of the pericarp wall, and consistency of the locular tissue. An NMR image at 256 × 256 pixel per image and 16 levels of intensity per pixel clearly showed many structural details of the fruit. Increased intensity was associated with liquefaction of the placental tissue during ripening, while grainines of the pericarp wall was associated with a decrease in wall density. In vivo NMR imaging of mature-green fruit produced images in which differences in maturity could be seen. The long required to produce an image and the cost of operation currently precludes the use of NMR imaging to sort mature-green tomato fruit.     

Genetic-diversity assessed by microsatellites in tropical maize populations submitted to a high-intensity reciprocal recurrent selection

BR-105 and BR-106 are important tropical maize populations, which were submitted to a high-intensity reciprocal recurrent selection, generating the IG-3 and IG-4synthetics. Using 30-microsatellite loci,we measured and compared the genetic diversity of these populations and their synthetics. The populations did not differ significantly regarding the amount of genetic diversity. As a consequence of selection, genetic variability losses, in terms of mean number of alleles per locus,proportion of polymorphic loci, and gene diversity did occur and were greater in the synthetic IG-3 than IG-4. In the synthetics, the number of loci in adherence to Hardy-Weinberg proportions was superior to that observed in the populations. The Wright's mean fixation index was higher than the mean value expected for outcrossing species (5%) indicating as light excess of homozygotic individuals in both populations. The genetic distances confirmed the favourable effects of one cycle of recurrent selection, as the synthetics became more isolated in comparison to the original populations. This revised version was published online in July 2006 with corrections to the Cover Date.     

The transfer of the synaptic gene (sy-2) from 1EBN Solanum commersonii Dun. to 2EBN germplasm

Summary Crosses of a synaptic mutant (sy-2) of 2x(1EBN) S. commersonii Dun. with 2x(2EBN) S. chacoense Bitt. resulted in the production of 3x(2EBN) hybrids. Low levels of 2n egg production in these hybrids allowed subsequent crosses to be made with 4x(4EBN) cultivars, resulting in 5x(4EBN) S. commersonii-S. chacoense-Group Tuberosum hybrids. Seed set in these crosses averaged 0.22 seeds per fruit. Fifty-four unspotted seeds were produced in 1225 crosses of the 5x(4EBN) hybrids with 2x(2EBN) Group Phureja haploid extraction clones carrying dominant seed spot markers. These seeds yielded a total of 15 confirmed haploids having a diploid (2n=2x=24) or near diploid chromosome number. One haploid clone recovered displayed a synaptically abnormal phenotype similar to the original S. commersonii synaptic mutant. Preliminary test crosses of these haploids indicated that all haploids produced were 2EBN.This method for the transfer of alleles across EBN levels holds promise for the recovery of both qualitative and quantitative traits from 1EBN species. In these recovered, cross-compatible forms, clones with desired characteristics may be selected and easily incorporated into breeding programs.