Spontaneous malignomas inTupaia (tree shrew)

Metastasis in the wild: investigating metastasis in non-laboratory animals

Humans are not the only species to spontaneously develop metastatic cancer as cases of metastasis have been reported in a wide range of animals, including dinosaurs. Mouse models have been an invaluable tool in experimental and clinical metastasis research, with the use of genetically-engineered mouse models that spontaneously develop metastasis or ectopic/orthotopic transplantation of tumour cells to wildtype or immunodeficient mice being responsible for many key advances in our understanding of metastasis. However, are there other species that can also be relevant models? Similarities to humans in terms of environmental exposures, life-span, genetics, histopathology and available therapeutics are all factors that can be considered when looking at species other than the laboratory mouse. This review will explore the occurrence of metastasis in multiple species from a variety of domestic, captive and free-living veterinary cases to assist in identifying potential alternative experimental and clinical research models relevant to humans.

A novel fish herpesvirus of Osmerus eperlanus

A herpesvirus of smelt (Osmerus eperlanus) was identified by thin section electron microscopy. Degenerated cells of skin lesions located on the back fin of smelt showed either intranucleic- or cytoplasmic herpesvirus-specific structures. In the nuclei "naked" virus capsids with a diameter of about 100 nm were observed. The diameter of the complete virion including its unilaterally extended envelope ranged from 200 to 350 nm. Remarkably, in complete virions the electron-opaque tegument is completely filling the region between nucleocapsid and envelope and as another unique feature the virion shows a "comet-shape" due to a long unilateral extension of its envelope. This kind of shape had been not reported for any of herpesviruses known so far. Consequently this virus was termed herpesvirus of Osmerus eperlanus (HVOE1) or Comet herpesvirus of smelt. Due to the long time storage at the nonstandard temperature of smelt virus the biological and genomic analysis of the HVOE1 was hampered. All attempts to study host range of HVOE1 failed as no virus replication was observed, indicating that infectivity was lost or the suitable cell culture was missing. The genomic DNA of HVOE1 was analyzed by DNA restriction endonucleases.

Tumors of the respiratory tract observed at the German Primate Center, 1978-1994

Eight spontaneous pulmonary tumors (four bronchiolar tubular adenomas, two bronchiolar adenocarcinomas, two squamous-cell carcinomas) occurred in a total of 54 adult tree shrews (Tupaia belangeri) of the GPC colonies between 1978 and 1994. The adenomas and adenocarcinomas consisted of tubularly or trabecularly arranged cuboidal to cylindrical cells interspersed with some PAS-positive goblet cells, thus resembling the epithelial lining of respiratory bronchioles of tree shrews. The two squamous-cell carcinomas probably originated from the pulmonary alveoles. Three more pulmonary tumors (one small-cell carcinoma, one bronchial adenoma, one squamous-cell carcinoma) developed in 409 adult callitrichids of the GPC colonies during the same period, and one more bronchial adenoma was observed in a common marmoset (Callithrix jacchus) of another colony located in Göttingen. With regard to the adenomas and squamous-cell carcinomas, a similar cellular origin with the three shrews is assumed. The small-cell carcinoma possibly developed from the bronchial epithelium, provided a pathogenesis parallel to that of human small-cell carcinoma is suggested. Four of the tree shrew pulmonary adenomas/adenocarcinomas and the small-cell Ca were macroscopically visible as yellowish-grey nodules of 1 mm x 1 mm to 15 mm x 15 mm diameter, predominantly involving the main lobes (2 x right main lobes, 2 x left main lobes, 1 x all lobes). The pulmonary tumors of the other animals were below macroscopical detectability.

Molecular cloning and physical mapping of the tupaia herpesvirus genome

Purified virion DNA of about 200 kilobase pairs of tupaia herpesvirus strain 2 was cleaved with EcoRI or HindIII restriction endonuclease. Restriction fragments representing the complete viral genome including both termini were inserted into the EcoRI, HindIII, and EcoRI-HindIII sites of the bacterial plasmid pAT153. Restriction maps for the restriction endonucleases EcoRI and HindIII were constructed with data derived from Southern blot hybridizations of individual viral DNA fragments or cloned DNA fragments which were hybridized to either viral genome fragments or recombinant plasmids. The analysis revealed that the tupaia herpesvirus genome consists of a long unique sequence of 200 kilobase pairs and that inverted repeat DNA sequences of greater than 40 base pairs do not occur, in agreement with previous electron microscopic data. No DNA sequence homology was detectable between the tupaia herpesvirus DNA and the genome of murine cytomegalovirus, which was reported to have a similar structure. In addition, seven individual isolates of tupaia herpesvirus were characterized. The isolates can be grouped into five strains by their DNA cleavage patterns.

Influence of stress on adrenocortical function in the male tree shrew (Tupaia belangeri)

Adrenocortical function in the tree shrew (Tupaia belangeri) was evaluated by reference to levels of individual corticosteroids as an initial phase in the clarification of the hormonal mechanisms by which stress influences male reproductive function. Corticosteroids were separated with Sephadex LH-20 chromatography and measured by specific radioimmunoassay procedures. Corticosterone was the principal corticosteroid in the peripheral plasma and in unstressed animals the ratio corticosterone:cortisol was 4.5:1 (1000 hr samples). Basal levels of corticosterone and cortisol exhibited parallel diurnal fluctuations with a peak at 0600 hr preceding the onset of daily activity and similar to that described for other diurnally active species. Levels of corticosterone and cortisol were markedly elevated 10 min after either restraint stress applied at various times during the day or ACTH administration to both saline- and dexamethasone-pretreated animals. In each of these experimental situations cortisol showed a greater relative increase from basal levels as compared to corticosterone resulting in a decline in the ratio corticosterone:cortisol. For example, the unstressed ratio of corticosterone (9.1 +/- 0.8 ng/ml) and cortisol (2.0 +/- 0.2 ng/ml) at 1000 hr was 4.5:1. Following 10 min of restraint stress the ratio declined to 1.5:1 (corticosterone, 44.9 +/- 1.4 ng/ml; cortisol, 31.7 +/- 1.3 ng/ml). An increase in cortisol is considered to be an important component of the physiological response to stress by the tree shrew adrenal. It is concluded that the adrenal cortex of the tree shrew normally produces corticosteroids through two pathways and the secretion of both corticosterone and cortisol are responsive to acute ACTH stimulation and feedback inhibition by dexamethasone.(ABSTRACT TRUNCATED AT 250 WORDS)