41 research outputs found
Characterization of a Complete Genome Sequence of Molluscum Contagiosum Virus from an Adult Woman in Australia
The complete genome sequence of molluscum contagiosum virus 1 (MOCV1) isolate NT2017 was sequenced from a tissue sample from an Australian woman. The genome consisted of 185,655 bp encoding 169 predicted open reading frames. Phylogenetically, isolate NT2017 was most closely related to an MOCV1 strain from Slovenia
A genetic linkage map for the saltwater crocodile (Crocodylus porosus)
<p>Abstract</p> <p>Background</p> <p>Genome elucidation is now in high gear for many organisms, and whilst genetic maps have been developed for a broad array of species, surprisingly, no such maps exist for a crocodilian, or indeed any other non-avian member of the Class Reptilia. Genetic linkage maps are essential tools for the mapping and dissection of complex quantitative trait loci (QTL), and in order to permit systematic genome scans for the identification of genes affecting economically important traits in farmed crocodilians, a comprehensive genetic linage map will be necessary.</p> <p>Results</p> <p>A first-generation genetic linkage map for the saltwater crocodile (<it>Crocodylus porosus</it>) was constructed using 203 microsatellite markers amplified across a two-generation pedigree comprising ten full-sib families from a commercial population at Darwin Crocodile Farm, Northern Territory, Australia. Linkage analyses identified fourteen linkage groups comprising a total of 180 loci, with 23 loci remaining unlinked. Markers were ordered within linkage groups employing a heuristic approach using CRIMAP v3.0 software. The estimated female and male recombination map lengths were 1824.1 and 319.0 centimorgans (cM) respectively, revealing an uncommonly large disparity in recombination map lengths between sexes (ratio of 5.7:1).</p> <p>Conclusion</p> <p>We have generated the first genetic linkage map for a crocodilian, or indeed any other non-avian reptile. The uncommonly large disparity in recombination map lengths confirms previous preliminary evidence of major differences in sex-specific recombination rates in a species that exhibits temperature-dependent sex determination (TSD). However, at this point the reason for this disparity in saltwater crocodiles remains unclear.</p> <p>This map will be a valuable resource for crocodilian researchers, facilitating the systematic genome scans necessary for identifying genes affecting complex traits of economic importance in the crocodile industry. In addition, since many of the markers placed on this genetic map have been evaluated in up to 18 other extant species of crocodilian, this map will be of intrinsic value to comparative mapping efforts aimed at understanding genome content and organization among crocodilians, as well as the molecular evolution of reptilian and other amniote genomes. As researchers continue to work towards elucidation of the crocodilian genome, this first generation map lays the groundwork for more detailed mapping investigations, as well as providing a valuable scaffold for future genome sequence assembly.</p
Crocodilepox Virus Evolutionary Genomics Supports Observed Poxvirus Infection Dynamics on Saltwater Crocodile (Crocodylus porosus)
Saltwater crocodilepox virus (SwCRV), belonging to the genus Crocodylidpoxvirus, are large DNA viruses posing an economic risk to Australian saltwater crocodile (Crocodylus porosus) farms by extending production times. Although poxvirus-like particles and sequences have been confirmed, their infection dynamics, inter-farm genetic variability and evolutionary relationships remain largely unknown. In this study, a poxvirus infection dynamics study was conducted on two C. porosus farms. One farm (Farm 2) showed twice the infection rate, and more concerningly, an increase in the number of early- to late-stage poxvirus lesions as crocodiles approached harvest size, reflecting the extended production periods observed on this farm. To determine if there was a genetic basis for this difference, 14 complete SwCRV genomes were isolated from lesions sourced from five Australian farms. They encompassed all the conserved genes when compared to the two previously reported SwCRV genomes and fell within three major clades. Farm 2′s SwCRV sequences were distributed across all three clades, highlighting the likely mode of inter-farm transmission. Twenty-four recombination events were detected, with one recombination event resulting in consistent fragmentation of the P4c gene in the majority of the Farm 2 SwCRV isolates. Further investigation into the evolution of poxvirus infection in farmed crocodiles may offer valuable insights in evolution of this viral family and afford the opportunity to obtain crucial information into natural viral selection processes in an in vivo setting
Nucleic Acid Preservation Card Surveillance Is Effective for Monitoring Arbovirus Transmission on Crocodile Farms and Provides a One Health Benefit to Northern Australia
The Kunjin strain of West Nile virus (WNVKUN) is a mosquito-transmitted flavivirus that can infect farmed saltwater crocodiles in Australia and cause skin lesions that devalue the hides of harvested animals. We implemented a surveillance system using honey-baited nucleic acid preservation cards to monitor WNVKUN and another endemic flavivirus pathogen, Murray Valley encephalitis virus (MVEV), on crocodile farms in northern Australia. The traps were set between February 2018 and July 2020 on three crocodile farms in Darwin (Northern Territory) and one in Cairns (North Queensland) at fortnightly intervals with reduced trapping during the winter months. WNVKUN RNA was detected on all three crocodile farms near Darwin, predominantly between March and May of each year. Two of the NT crocodile farms also yielded the detection of MVE viral RNA sporadically spread between April and November in 2018 and 2020. In contrast, no viral RNA was detected on crocodile farms in Cairns during the entire trapping period. The detection of WNVKUN and MVEV transmission by FTATM cards on farms in the Northern Territory generally correlated with the detection of their transmission to sentinel chicken flocks in nearby localities around Darwin as part of a separate public health surveillance program. While no isolates of WNVKUN or MVEV were obtained from mosquitoes collected on Darwin crocodile farms immediately following the FTATM card detections, we did isolate another flavivirus, Kokobera virus (KOKV), from Culex annulirostris mosquitoes. Our studies support the use of the FTATM card system as a sensitive and accurate method to monitor the transmission of WNVKUN and other arboviruses on crocodile farms to enable the timely implementation of mosquito control measures. Our detection of MVEV transmission and isolation of KOKV from mosquitoes also warrants further investigation of their potential role in causing diseases in crocodiles and highlights a “One Health” issue concerning arbovirus transmission to crocodile farm workers. In this context, the introduction of FTATM cards onto crocodile farms appears to provide an additional surveillance tool to detect arbovirus transmission in the Darwin region, allowing for a more timely intervention of vector control by relevant authorities
Sequencing three crocodilian genomes to illuminate the evolution of archosaurs and amniotes
The International Crocodilian Genomes Working Group (ICGWG) will sequence and assemble the American alligator (Alligator mississippiensis), saltwater crocodile (Crocodylus porosus) and Indian gharial (Gavialis gangeticus) genomes. The status of these projects and our planned analyses are described
Evolution and gene capture in ancient endogenous retroviruses - insights from the crocodilian genomes
Simulating economic values of a genetic improvement program for Australian farmed saltwater crocodiles
In genetic improvement programs, candidates for breeders are ranked by the profitability
of their offspring, expressed as a weighted sum of the genetic gain from selection. In this
paper, we estimate the economic values of a genetic improvement program for Australian
farmed saltwater crocodiles. A bioeconomic profit function for a representative breeding
pair is used to determine the optimal slaughter age following genetic improvement
in each selection objective. The results indicate that estimated farm profitability
increases by nearly
#
A111 for a 1-week reduction in juvenile slaughter age,
#
A78 for a
1 per cent increase in the proportion of first-grade skins produced, and
#
A33 for an
increase in the number of viable hatchlings per clutch. The implications of the analysis
for the Australian crocodile industry and the limitations of the research are explored
Molecular characterization of the first saltwater crocodilepox virus genome sequences from the world’s largest living member of the Crocodylia
Abstract Crocodilepox virus is a large dsDNA virus belonging to the genus Crocodylidpoxvirus, which infects a wide range of host species in the order Crocodylia worldwide. Here, we present genome sequences for a novel saltwater crocodilepox virus, with two subtypes (SwCRV-1 and -2), isolated from the Australian saltwater crocodile. Affected belly skins of juvenile saltwater crocodiles were used to sequence complete viral genomes, and perform electron microscopic analysis that visualized immature and mature virions. Analysis of the SwCRV genomes showed a high degree of sequence similarity to CRV (84.53% and 83.70%, respectively), with the novel SwCRV-1 and -2 complete genome sequences missing 5 and 6 genes respectively when compared to CRV, but containing 45 and 44 predicted unique genes. Similar to CRV, SwCRV also lacks the genes involved in virulence and host range, however, considering the presence of numerous hypothetical and or unique genes in the SwCRV genomes, it is completely reasonable that the genes encoding these functions are present but not recognized. Phylogenetic analysis suggested a monophyletic relationship between SwCRV and CRV, however, SwCRV is quite distinct from other chordopoxvirus genomes. These are the first SwCRV complete genome sequences isolated from saltwater crocodile skin lesions
Crocodilepox Virus Evolutionary Genomics Supports Observed Poxvirus Infection Dynamics on Saltwater Crocodile (Crocodylus porosus)
Increasing photoperiod enhances growth in captive hatchling Caiman latirostris
Captive crocodilians reduce their intake of food during cold periods, even when kept under controlled conditions and fed ad libitum. These manifestations may be due to photoperiod length which is known to influence circadian rhythm. To test this hypothesis, 72 Caiman latirostris hatchlings from three wild-harvested nests, were reared under controlled conditions of temperature and humidity with varying hours of light exposure. Three treatments were performed: A) increasing photoperiod to 16 h light; B) decreasing photoperiod to 8 h light; C) and the control treatment with constant 12 h light / 12 h dark. Caiman growth was measured as both weight and linear measures (snout-vent length and total length). Individuals from the increased photoperiod treatment group (16 h) showed a significant increase in all growth parameters compared to other treatments (control = 12 h; reduced photoperiod = 8 h). There was no difference in stress (plasma corticosterone levels) between the treatment groups ensuring that the additional growth benefit was not antagonistic to welfare. From this, it can be postulated that photoperiod, along with availability of temperature, is another important factor which influences the growth of C. latirostris.Fil: Ciocan, Hernán. Universidad Nacional del Litoral. Facultad de Humanidades y Ciencias; Argentina. Provincia de Entre RĂos. Centro de Investigaciones CientĂficas y Transferencia de TecnologĂa a la ProducciĂłn. Universidad AutĂłnoma de Entre RĂos. Centro de Investigaciones CientĂficas y Transferencia de TecnologĂa a la ProducciĂłn. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Santa Fe. Centro de Investigaciones CientĂficas y Transferencia de TecnologĂa a la ProducciĂłn; ArgentinaFil: Imhof, Alba. Universidad Nacional del Litoral. Facultad de Humanidades y Ciencias; ArgentinaFil: Parachu Marco, Maria Virginia. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Santa Fe. Instituto de Ciencias Veterinarias del Litoral. Universidad Nacional del Litoral. Facultad de Ciencias Veterinarias. Instituto de Ciencias Veterinarias del Litoral; ArgentinaFil: Isberg, Sally R.. Centre for Crocodile Research; AustraliaFil: Siroski, Pablo Ariel. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. Universidad Nacional del Litoral. Facultad de Ciencias Veterinarias. Departamento de Ciencias MorfolĂłgicas. Laboratorio de BiologĂa Celular y Molecular; Argentina. Universidad Nacional del Litoral. Facultad de Humanidades y Ciencias; ArgentinaFil: Larriera, Alejandro. Universidad Nacional del Litoral. Facultad de Humanidades y Ciencias; Argentin