Prevalence and haematological changes associated with trypanosome infection in wild tilapia fish in Ibadan, Nigeria

There is paucity of information on the incidence and haematological changes associated with trypanosome infection in Nigerian fishes. This investigation examined randomly buffy coat and blood smears of Tilapia in the wild by direct microscopy for Trypanosomes and complete haematology were analyzed. Of the 200 samples collected, 17.5% were positive for trypanosome by buffy coat examination. The Packed cell volume (PCV) of trypanosome-infected fish was 15.3+ 0.9% compared to noninfected fish (p<0.01) with PCV of 38.4+1.3%. All the haematocrit values obtained in trypanosome-infected fish showed the pattern of anaemia in trypanosomiasis. The report establishes the fact that trypanosomiasis in fish is similar to those find in animals.Keywords: Tilapia, Wild, Trypanosome, Haematolog

Oral melanoma with pulmonary metastasis in a Nigerian local dog

Melanomas are the most commonly diagnosed neoplasm of the canine oral cavity accounting for about 7% of all malignant tumours in the dog. Less frequently, metastasis via regional lymph nodes and to the lungs and other organs may occur. A case report of oral melanoma with pulmonary metastasis in a Nigerian local dog is hereby presented. Grossly, irregularly shaped, markedly dark, soft mass was located beneath the premolar and molar teeth on the left mandible. The lungs were also covered with numerous raised, dark, glistening nodules of various sizes ranging from 0.2cm-0.5cm in diameter. Cytomorphological evaluation of the mass via impression smear stained with Giemsa revealed monomorphic round cells with deeply basophilic cytoplasm with grey to dark fine intracytoplasmic pigments. Histological section stained with Haematoxylin and Eosin revealed similar cells with fine grey to dark intracytoplasmic pigments.Keywords: Melanoma, One Health, Oral cavity, Pulmonary Metastasis, Tumo

Somatic evolution and global expansion of an ancient transmissible cancer lineage

The canine transmissible venereal tumor (CTVT) is a cancer lineage that arose several millennia ago and survives by “metastasizing” between hosts through cell transfer. The somatic mutations in this cancer record its phylogeography and evolutionary history. We constructed a time-resolved phylogeny from 546 CTVT exomes and describe the lineage's worldwide expansion. Examining variation in mutational exposure, we identify a highly context-specific mutational process that operated early in the cancer's evolution but subsequently vanished, correlate ultraviolet-light mutagenesis with tumor latitude, and describe tumors with heritable hyperactivity of an endogenous mutational process. CTVT displays little evidence of ongoing positive selection, and negative selection is detectable only in essential genes. We illustrate how long-lived clonal organisms capture changing mutagenic environments, and reveal that neutral genetic drift is the dominant feature of long-term cancer evolution. © 2019 American Association for the Advancement of Science. All rights reserved

Recurrent horizontal transfer identifies mitochondrial positive selection in a transmissible cancer

Autonomous replication and segregation of mitochondrial DNA (mtDNA) creates the potential for evolutionary conflict driven by emergence of haplotypes under positive selection for ‘selfish’ traits, such as replicative advantage. However, few cases of this phenomenon arising within natural populations have been described. Here, we survey the frequency of mtDNA horizontal transfer within the canine transmissible venereal tumour (CTVT), a contagious cancer clone that occasionally acquires mtDNA from its hosts. Remarkably, one canine mtDNA haplotype, A1d1a, has repeatedly and recently colonised CTVT cells, recurrently replacing incumbent CTVT haplotypes. An A1d1a control region polymorphism predicted to influence transcription is fixed in the products of an A1d1a recombination event and occurs somatically on other CTVT mtDNA backgrounds. We present a model whereby ‘selfish’ positive selection acting on a regulatory variant drives repeated fixation of A1d1a within CTVT cells. © 2020, The Author(s)