Origins and diversity of the Portuguese Landrace of Eucalyptus globulus

The Portuguese Landrace of Eucalyptus globulus is of unknown origin, with the earliest plantings of this tree species dating back to the early 19th century. In Portugal it is currently a major seed source for plantations and is also used in breeding programs. Eucalyptus globulus is native to south-eastern Australia. The substantial genetic differentiation of chloroplast and nuclear DNA markers between different native geographic races of this species allowed us to uncover the Australian origins of the Portuguese Landrace and to study its genetic diversity. To achieve this, we sequenced a highly polymorphic region of chloroplast DNA from 47 Portuguese Landrace individuals, and genotyped 34 of these using seven nuclear microsatellites. We compared these individuals to those in a database comprising chloroplast DNA sequence profiles from 292 native trees and seven nuclear microsatellites from 372 native trees. The majority of the Portuguese Landrace samples had closest affinities, in both marker systems, to native trees from south-eastern Tasmania, but some had affinities to trees from south-eastern Victoria. The discrepancies in the affinities indicated by chloroplast versus nuclear DNA markers could be explained by inter-race hybridisation after introduction. The genetic diversity in the Portuguese Landrace was less than that found in native E. globulus at the species level, but was similar to the average diversity found in native races of the species. This study demonstrates the power of using independent marker systems to identify the origins and diversity of domesticated populations, by comparison with variation in native stands.     

Gene flow between introduced and native Eucalyptus species

The first evidence of in situ F₁ hybridisation between an introduced eucalypt plantation species, Eucalyptus nitens, and a native eucalypt species is presented. Open-pollinated seed was collected from a mature E. nitens trial and from the adjacent native species, E. ovata and E. viminalis on the island of Tasmania. Nearly 70 000 seedlings were grown to a size at which hybrids could be clearly distinguished from pure species seedlings on the basis of morphology and a nearly species-specific isozyme allele. Hybridisation was observed between E. nitens and E. ovata, but no hybrids involving E. viminalis were found. This pattern of hybridisation was consistent with the flowering time overlap between the E. ovata and E. nitens. Eucalyptus nitens progenies displayed a low and relatively homogeneous level of hybridisation, averaging 0.15% per tree. In comparison, the proportion of hybrids obtained from the adjacent E. ovata trees varied from 0.04 to 16% per tree. Whether progeny arising from such hybridisation will survive and grow in nature to allow for backcrossing and introgression of the exotic genes into the native population is not yet known.     

Patterns of longitudinal within-tree variation in pulpwood and solidwood traits differ among Eucalyptus globulus genotypes

Wood discs were sampled from 6 heights up the stem of 248 trees representing 10 subraces and 116 families grown in an E. globulus base-population progeny trial. The lower stem had the least favourable wood properties for kraft pulpwood and most solidwood applications: bark was thickest, basic density was lowest and kino, decay and shrinkage traits were greatest at or below 12% of tree height. Significant genetic differences at the subrace level were revealed in diameter, bark thickness, basic density, decay and gross shrinkage and at the family within subrace level in diameter, basic density and decay. However, subrace-by-height-category interactions in bark thickness, basic density, decay and gross shrinkage indicated that differences among subraces were dependent on height in these traits. Examination of longitudinal trends revealed some evidence that the zone of thick basal bark extended further up the stem in thicker-barked subraces and that the Southern Tasmania subrace might be less effective than other subraces in restricting the longitudinal spread of decay after infection.     

Analysis of leukocyte populations in Canadian Holsteins classified as high or low immune responders for antibody- or cell-mediated immune response

Selection of dairy cattle for increased milk production with little or no emphasis on health traits leads to an increased prevalence of disease. A possible genetic solution to this problem is to combine production and immune response traits in a weighted selection index. In the current study, leukocyte populations in heifers identified as having a high antibody-mediated immune response (HiAMIR) or high cell-mediated immune response (HiCMIR) phenotype were compared before and after immunization in order to identify leukocyte population profiles associated with these phenotypes. The results demonstrated that the HiCMIR-phenotype animals had a higher baseline proportion of gamma-delta T-cells in peripheral blood. Also, the observed increase in the proportion of B-cells in peripheral blood in response to immunization was greater in the HiAMIR-phenotype animals. It is expected that identifying leukocyte population profiles associated with immune response phenotypes will improve our ability to identify animals with enhanced overall immune responsiveness.     

Validation of an immunohistochemical assay for bovine cysticercosis, with comparison to a standard histological method

The larval stage (syn Cysticercus bovis) of the human tapeworm Taenia saginata causes cysticercosis in cattle, which has both aesthetic and food safety implications to consumers of beef. A monoclonal antibody-based immunohistochemical (IHC) assay developed to improve postmortem diagnosis of this parasite and a standard histological method were assessed to determine their fitness for intended use. Sections from 169 known-positive specimens of T. saginata from experimentally or naturally infected cattle, and from 30 known-negative specimens and lesions of various etiologies from non-infected cattle, were tested. The IHC assay identified significantly more known positive bovine cysticerci than the histological method (91.7% and 38.5%, respectively). Positive IHC staining occurred on sections from other cestode species, but should not affect the diagnostic specificity of this assay for bovine cysticercosis, due to the different host and/or tissue preferences amongst these parasites. Use of the IHC assay should improve the reliability of diagnosing lesions caused by degenerated cysticerci, facilitating more effective and efficient control of bovine cysticercosis.     

Survey of factors influencing faculty decisions on international veterinary work

Faculty members at US colleges of veterinary medicine can encounter opportunities to work as a veterinarian in a foreign country. Institutions, governments, and other organizations can more effectively recruit faculty for these positions if they understand the characteristics of the individuals who are most likely to participate in these programs. The purpose of this study was to determine what characteristics influence veterinary faculty's desire to participate in foreign programs. Results illustrated that position type (tenure, clinical), rank (assistant professor, associate professor, full professor), gender, and the presence of pre-elementary aged children were significantly associated with willingness to work in a foreign country. In addition, survey respondents who indicated that the duration of the assignment was of high importance were less willing to travel than respondents who indicated that the duration of the assignment was of moderate importance or lower. The results from this survey provide important information about the characteristics of individuals more willing to participate in foreign programs. This information allows targeted recruiting by organizations, facilitating veterinary work in foreign countries.     

Global Recognition of Qualified Toxicologic Pathologists: Credential Review as a Potential Route for Recognizing the Proficiency of Pathologists Involved in Regulatory-type Nonclinical Studies

Recent international summits of the International Federation of Societies of Toxicologic Pathologists (IFSTP) have debated the desirability and potential means by which the proficiency of an individual toxicologic pathologist might be recognized and communicated throughout the world. The present document describes the advantages and disadvantages of implementing such a global recognition system by any means, and provides a proposal whereby recognition might be accorded via rigorous credential review of a practitioner's education and experience.