The frog Xenopus laevis has provided significant insights into developmental and cellular processes. However, X. laevis has an allotetraploid genome precluding its use in forward genetic analysis. Genetic analysis may be applicable to Xenopus (Silurana) tropicalis, which has a diploid genome and a shorter generation time. Here, we show that many tools for the study of X. laevis development can be applied to X. tropicalis. By using the developmental staging system of Nieuwkoop and Faber, we find that X. tropicalis embryos develop at similar rates to X. laevis, although they tolerate a narrower range of temperatures. We also show that many of the analytical reagents available for X. laevis can be effectively transferred to X. tropicalis. The X. laevis protocol for whole-mount in situ hybridization to mRNA transcripts can be successfully applied to X. tropicalis without alteration. Additionally, X. laevis probes often work in X. tropicalis-alleviating the immediate need to clone the X. tropicalis orthologs before initiating developmental studies. Antibodies that react against X. laevis proteins can effectively detect the X. tropicalis protein by using established immunohistochemistry procedures. Antisense morpholino oligonucleotides (MOs) offer a new alternative to study loss of gene activity during development. We show that MOs function in X. tropicalis. Finally, X. tropicalis offers the possibility for forward genetics and genomic analysis.

Mycobacterium pseudoshottsii sp. nov., a slowly growing chromogenic species isolated from Chesapeake Bay striped bass (Morone saxatilis) A group of slowly growing photochromogenic mycobacteria was isolated from Chesapeake Bay striped bass (Morone saxatilis) during an epizootic of mycobacteriosis. Growth characteristics, acid-fastness and 16S rRNA gene sequencing results were consistent with those of the genus Mycobacterium. Biochemical reactions, growth characteristics and mycolic acid profiles (HPLC) resembled those of Mycobacterium shottsii, a non-pigmented mycobacterium also isolated during the same epizootic. Sequencing of the 16S rRNA genes, the gene encoding the exported repeated protein (erp) and the gene encoding the 65 kDa heat-shock protein (hsp65) and restriction enzyme analysis of the hsp65 gene demonstrated that this group of isolates is unique. Insertion sequences associated with Mycobacterium ulcerans, IS2404 and IS2606, were detected by PCR. These isolates could be differentiated from other slowly growing pigmented mycobacteria by their inability to grow at 37 6C, production of niacin and urease, absence of nitrate reductase, negative Tween 80 hydrolysis and resistance to isoniazid (1 mg ml "1 ), p-nitrobenzoic acid, thiacetazone and thiophene-2-carboxylic hydrazide. On the basis of this polyphasic study, it is proposed that these isolates represent a novel species, Mycobacterium pseudoshottsii sp. nov. The type strain, L15 T , has been deposited in the American Type Culture Collection as ATCC BAA-883 T and the National Collection of Type Cultures (UK) as NCTC 13318 T .

Mycobacterium ulcerans, the causative agent of Buruli ulcer, produces a macrolide toxin, mycolactone A/B, which is thought to play a major role in virulence. A disease similar to Buruli ulcer recently appeared in United States frog colonies following importation of the West African frog, Xenopus tropicalis. The taxonomic position of the frog pathogen has not been fully elucidated, but this organism, tentatively designated Mycobacterium liflandii, is closely related to M. ulcerans and Mycobacterium marinum, and as further evidence is gathered, it will most likely be considered a subspecies of one of these species. In this paper we show that M. liflandii produces a novel plasmid-encoded mycolactone, mycolactone E. M. liflandii contains all of the genes in the mycolactone cluster with the exception of that encoding CYP140A2, a putative p450 monooxygenase. Although the core lactone structure is conserved in mycolactone E, the fatty acid side chain differs from that of mycolactone A/B in the number of hydroxyl groups and double bonds. The cytopathic phenotype of mycolactone E is identical to that of mycolactone A/B, although it is less potent. To further characterize the relationship between M. liflandii and M. ulcerans, strains were analyzed for the presence of the RD1 region genes, esxA (ESAT-6) and esxB (CFP-10). The M. ulcerans genome strain has a deletion in RD1 and lacks these genes. The results of these studies show that M. liflandii contains both esxA and esxB.

Fatty liver hemorrhagic syndrome, characterized by sudden death in overconditioned hens due to hepatic rupture and hemorrhage, is one of the leading noninfectious idiopathic causes of mortality in backyard chickens. Nutritional, genetic, environmental, and hormonal factors, or combinations of these, have been proposed yet not proven as the underlying cause. In an attempt to characterize the hepatic changes leading to the syndrome, this retrospective case study examined 76 backyard chickens that were diagnosed with fatty liver hemorrhagic syndrome between January 2007 and September 2012 and presented for necropsy to the diagnostic laboratory of the California Animal Health and Food Safety Laboratory System. A majority of the birds were female (99%), obese (97.5%), and in active lay (69.7%). Livers were examined histologically, and the degree of hepatocellular vacuolation (lipidosis), the reticular stromal architecture, the presence of collagenous connective tissue, and vascular wall changes were evaluated and graded using hematoxylin and eosin, Gomori's reticulin, oil red O, Masson's trichrome, and Verhoeff-Van Gieson stains. Interestingly, there was no correlation between lipidosis and reticulin grades; hepatocellular lipidosis was absent in 22% of the cases and mild in 26% of the cases. Additionally, there was evidence of repeated bouts of intraparenchymal hemorrhage before the acute "bleed-out" in 35.5% of the cases. These data are not supportive of the previously proposed causes and provide a framework for future studies to elucidate the pathogenesis of this condition. Furthermore, the data shown in this study support hemorrhagic liver syndrome as a more accurate name, as hepatic lipidosis is absent in a significant proportion of ruptured livers.

In sub-Saharan Africa, HIV-1 infection frequently occurs in the context of other coinfecting pathogens, most importantly, Mycobacterium tuberculosis and malaria parasites. The consequences are often devastating, resulting in enhanced morbidity and mortality. Due to the large number of confounding factors influencing pathogenesis in coinfected people, we sought to develop a nonhuman primate model of simian immunodeficiency virus (SIV)-malaria coinfection. In sub-Saharan Africa, Plasmodium falciparum is the most common malaria parasite and is responsible for most malaria-induced deaths. The simian malaria parasite Plasmodium fragile can induce clinical symptoms, including cerebral malaria in rhesus macaques, that resemble those of P. falciparum infection in humans. Thus, based on the well-characterized rhesus macaque model of SIV infection, this study reports the development of a novel rhesus macaque SIV-P. fragile coinfection model to study human HIV-P. falciparum coinfection. Using this model, we show that coinfection is associated with an increased, although transient, risk of both HIV and malaria transmission. Specifically, SIV-P. fragile coinfected macaques experienced an increase in SIV viremia that was temporarily associated with an increase in potential SIV target cells and systemic immune activation during acute parasitemia. Conversely, primary parasitemia in SIV-P. fragile coinfected animals resulted in higher gametocytemia that subsequently translated into higher oocyst development in mosquitoes. To our knowledge, this is the first animal model able to recapitulate the increased transmission risk of both HIV and malaria in coinfected humans. Therefore, this model could serve as an essential tool to elucidate distinct immunological, virological, and/or parasitological parameters underlying disease exacerbation in HIV-malaria coinfected people.