The neotropical genus Exostema comprises 25 species of trees and shrubs, ranging in distribution from Bolivia to Mexico and throughout the West Indies, with most species endemic to the Greater Antilles. Infrageneric relationships and species-level patterns of evolution were investigated in phylogenetic analyses using morphological, molecular, and combined data sets. All data sets resolved three main species groups which correspond to the three sections recognized by McDOWELL (1996). However, the analyses of ITS sequence data placed the two South American species basal to the three main clades. Otherwise, the morphological and molecular data are highly compatible, and produce a more robust yet consistent phylogeny in the combined data analysis. Morphological evolution in Exostema involves many specializations for xeric habitats, reflecting repeated ecological shifts from moist forest to exposed, seasonally dry environments during the diversification of the genus. Both moth and bee pollination syndromes are found in Exostema, and shifts in pollination ecology appear pivotal to the differentiation of the three sections. Biogeographically, Exostema likely originated in South America and migrated via Central America to the Greater Antilles, where the morphological diversification and speciation are most extensive.

"2003". / Thesis (PhD)--Macquarie University, Division of Environmental & Life Sciences, Department of Biological Sciences, 2004. / Bibliography: leaves 136-160. / Introduction: The Antarctic environment; Antarctic inhabitants; Microfungi; Identification of microfungi; Physiological factors affecting Antactic microfungi; Flow cytometry and microfungi; Hydrolytic enzymes of industrial interest; Isolation of genes from microfungi; Aims of this study -- Materials and methods: Fungal strains and cultivation conditions; Molecular identification of fungal isolates; Fungal physiology; Hydrolase activity of secreted proteins; Gene cloning and expression -- Results and discussion: Microfungal identification; Physiological factors affecting Antarctic microfungi; Activity in microfungi when grown on solid media; Characterisation of hemicellulases from selected Antarctic microfungi; Cloning of an Antarctic Penicillium allii lipase gene and its expression in Trichoderma reesei -- Conclusions and future prospects. / The Antarctic occupies that region of the planet that falls below the 60th parallel of South latitude. Although it has been frequented by adventurers, journeyman scientists and tourists for the past 100 years, the Continent has remained virtually unoccupied. The intense cold, the absence of human occupation and the limited range of local higher animal species have combined to create the impression that the Continent is virtually devoid of life. -- Although the microbiota of the Antarctic has attracted some small level of attention in the past, the examination of filamentous microfungi has been largely overlooked and fallen to a small group of dedicated investigators. In this study it will be shown that far from being an insignificant component of the Antarctic network, microfungi represent a potentially large and so far untapped bioresource. -- From just 11 bryophyte samples collected at four sites in the Ross Sea/Dry Valleys region of Southern Antarctica, some 30 microfungal isolates were recovered. Using molecular techniques, the internal transcribed spacer (ITS) region of the nuclear ribosomal DNA (nrDNA) was sequenced to reveal no less than nine unique microfungal species. For only two of these species did the ITS sequence data produce a 100% match with records held on the public databases. This investigation also highlighted the problems inherent in the traditional morphological identification system which are now being perpetuated in the molecular database records. -- A set of seven notionally identified isolates obtained from ornithogenic soil samples gathered in the Windmill Islands in Eastern Antarctica (offshore from the Australian Antarctic Division's Casey Station) were also subjected to molecular identification based on ITS sequence data. Each of the seven isolates was identified as a unique species; six were cosmopolitan in nature and the one remaining bore very little resemblance at the molecular level to any of the recorded species although it was provided with an epithet commonly used in the identification of Antarctic microfungal species. -- To evaluate their potential as a bioresource, samples of Antarctic microfungi were examined to determine if the same physiological factors common to mesophilic species also applied to their Antarctic analogues. It is known that when placed under stress, trehalose can act as a protectant against cold (cryoprotection) and dehydration in mesophilic yeasts and fungi. The level of trehalose produced by the Antarctic isolates and their mesophilic analogues when subjected to stress was compared. A similar comparison was made for the production of glycerol which is well established as a compatible solute providing protection to mesophilic species against osmotic stress. Only in the case of trehalose production by an Antarctic Embellisia was there any indication that either of these two compounds could play a significant role in providing protection to the Antarctic fungi against the rigours of their environment, which leaves open to question what in fact does. -- In the course of investigating the means by which Antarctic microfungi guard against the damage which can ensue when subjected to oxidative stress, flow cytometry was introduced as an investigatory tool. It was established that there is a window of opportunity during which flow cytometry can be used to undertake a detailed analysis of the early stages of fungal growth from germination through hyphal development. -- Of major significance in determining the potential of Antarctic microfungi as a resource is their ability to produce new and novel enzymes and proteins. The microfungal isolates were screened for hydrolytic activity on solid media containing indicative substrates and proved to be a fruitful source of enzymes active over a range of temperatures. A detailed characterisation of two hemicellulases, β-mannanase and xylanase, secreted into a liquid medium by a subset of the Antarctic fungi and a high producing mesophilic reference strain permitted direct comparisons to be made. It was shown that the maximum hemicellulase activity of the Antarctic strains occurred at least 10°C and as much as 30°C lower than that of the reference strain and that mannanase activity for two of the Antarctic isolates exceeded 40% of their maximum at 0°C. These assay results highlight the potential of Antarctic microfungi to yield novel cold-active enzymes. -- As a final measure of the capacity of the Antarctic to yield novel enzymes from its microfungal stock, a lipase gene was selected as a target for isolation and expression in a heterologous fungal host. Using PCR techniques, the gene of interest was isolated from an Antarctic isolate of Penicillium allii, transformed into the mesophilic production host Trichoderma reesei and the active protein successfully produced in the growth medium. The recombinant lipase was assayed and found to exhibit novel characteristics consistent with a cold-adapted enzyme. / Mode of access: World Wide Web. / 186 leaves ill

<p dir="ltr">ABSTRACT</p><p dir="ltr">Bovine Respiratory Disease (BRD) poses a significant challenge in the dairy and beef industry, contributing to high mortality, morbidity, and economic costs. Extensive research has aimed to enhance BRD diagnosis, focusing on various factors such as predisposition, environment, and epidemiology. While diverse methods have been developed for BRD detection, including clinical signs, behavioral changes, lung consolidation assessment via ultrasonography, and molecular techniques for microbiome analysis, accurate diagnosis remain inconsistent. Notably, many studies lack exploration of microbial interactions (fungi, viruses, and bacteria) within BRD-affected animals compared to healthy ones. Moreover, the impact of age, disease, and antibiotic treatment on the microbiome community remains understudied. Thus, additional analysis is crucial to understand the relationships between these factors and BRD development. This dissertation is divided into two parts, each addressing specific conditions. The first part focuses on characterizing the nasopharyngeal (NP) microbiome of dairy calves, pre-weaned and post-transported, and those diagnosed with BRD within the first two weeks of life. The objective is to identify NP microbiome changes as indicators of disease development, considering antibiotic treatment effects on NP alpha and beta diversity. The second part delves into characterizing the fungal and bacterial nasal cavity among BRD-affected and healthy cattle within the same pen. This section, presented in three chapters, explores the bovine nasal mycobiome in beef cattle, as well as the nasal microbiome in both dairy and beef cattle. The overarching goals of these studies are to evaluate differences in the nasal mycobiome or microbiome community between BRD-affected and healthy cattle, focusing on alpha, beta, and community compositions as potential disease indicators. Additionally, the aim is to determine if BRD-affected cattle exhibit higher abundance of BRD-pathobionts (fungi and bacteria) in the nasal cavity compared to healthy pen-mates. In conclusion, findings from this research emphasize the importance of incorporating both mycobiome and microbiome analyses in understanding BRD development. Future studies should consider geographical influences on nasal microbiome structure, highlighting the need for separate investigations in dairy and beef calves due to breed variations. Ultimately, studying mycobiome and microbiome ecology offers insights into microbial transitions from commensal to pathogenic farms in the bovine upper respiratory tract, supporting advancements in BRD prevention or mitigation strategies.</p>