Cryo-archiving of Batrachochytrium dendrobatidis and other chytridiomycetes.

Batrachochytrium dendrobatidis is a major pathogen of frogs worldwide. It has been associated with catastrophic declines of frog populations including those in pristine habitats in Queensland, Australia. To facilitate genetic and disease studies of this fungus and related species, it is essential to have a reliable long-term storage method to maintain genetic integrity of isolates. We have adapted well-established techniques used for the long-term storage of tissue-culture cell lines to the preservation of B. dendrobatidis and other chytridiomycetes. This simple method has allowed us to recover these fungi from storage at -80 degrees C and in liquid nitrogen over an extended period. With this technique it is now possible to preserve saprobic and parasitic isolates from a variety of environmental and disease situations for comparative genetic and biological studies.

First identification of a ranavirus from green pythons (Chondropython viridis).

Ten juvenile green pythons (Chondropython viridis) died or were euthanized shortly after having been illegally imported into Australia from Indonesia in 1998. Histologic examination of two of the three snakes that died revealed moderately severe chronic ulceration of the nasal mucosa and focal or periacinar degeneration and necrosis of the liver. In addition there was severe necrotizing inflammation of the pharyngeal submucosa accompanied by numerous macrophages, heterophils, and edema. An iridovirus was isolated in culture from several tissues and characterized by immunohistochemistry, electron microscopy, enzyme-linked immunosorbent Assay, polyacrylamide gel electrophoresis, polymerase chain reaction and sequence analysis, restriction endonuclease digestion, and DNA hybridization. This is the first report of a systemic ranavirus infection in any species of snake and is a new member of the genus, Ranavirus.

Ultrastructure of Hendra virus and Nipah virus within cultured cells and host animals.

The ultrastructure of Hendra and Nipah viruses is described in cultured cells, pigs, horses and humans. Differences in ultrastructure between the viruses are evident within infected cell cultures and lungs from infected amplifier hosts. These differences are important in viral identification and differentiation and understanding the pathogenesis of disease.

Distribution of sympathetic neuroeffector junctions in the juxtaglomerular region of the rabbit kidney.

Two structurally distinct types of sympathetic axon (Type I and Type II) have recently been identified in the renal cortex of the rat and the rabbit. This study describes the distribution and density of the neuroeffector junctions made by these two types of axon on the different tissues from the juxtaglomerular region of the rabbit renal cortex. Immunohistochemical studies showed that tyrosine hydroxylase-positive axons were located only in regions adjacent to the arteries and arterioles in the renal cortex. Ultrastructural studies of the juxtaglomerular region indicated that both types of axon formed junctions on vascular smooth muscle cells, epithelial cells of proximal tubules and renin-secreting granular epithelioid cells. The density of neuromuscular junctions (18 x 10(3)/mm2 of vessel surface) was more than twice as high on the afferent arteriole as on the efferent arteriole or proximal tubules immediately adjacent to the glomerular arterioles (both about 6 x 10(3)/mm2). The junction density on granular epithelioid cells was much lower (about 2 x 10(3)/mm2) and were rarely observed on the distal tubule. Afferent arterioles preferentially received junctions from Type I axons at a relatively high density (14.2 x 10(3)/mm2) whereas junctions formed by Type II axons were less selectively distributed and occurred at lower densities on all other tissues (range, 1-6.3 x 10(3)/mm2). Presynaptic membrane specialisations were identified only at junctions on arterioles and granular epithelioid cells and occurred more frequently at Type I than at Type II junctions. The data suggest that the predominant effect of the sympathetic innervation in the juxtaglomerular region of the renal cortex is on the afferent arteriole and that the two axon types within the kidney may have different functions.

Two types of sympathetic axon innervating the juxtaglomerular arterioles of the rabbit and rat kidney differ structurally from those supplying other arteries.

Ultrastructural analyses of serial thin sections have revealed two structurally different types of sympathetic axon innervating the afferent and efferent juxtaglomerular arterioles and the intralobular arteries in the outer cortex of the rabbit kidney. Both types of axon have also been found in association with an afferent arteriole in rat kidney. One axon type consists of relatively large diameter unmyelinated axons bearing varicosities in the form of slight expansions. The varicosities have a distinct structural zonation: synaptic vesicles occupy the expansion which faces the smooth muscle cells, whereas the rest of the axon is filled with numerous microtubules. The other axon type has varicosities containing vesicles and mitochondria but few microtubules. The varicosities are generally small and the intervaricosities very thin. The relationship of both axon types with support cells and/or basal lamina is sometimes poorly defined. Both axon types are catecholaminergic as their vesicles take up 6-hydroxydopamine and both types form junctions with arteriolar smooth muscle cells. As well as differing from each other, both types of intrarenal axon differ in several respects from those which innervate other arterial vessels.