Academic literature on the topic 'Founder viruses'

In addition to grazing, another form of top-down control of microbes is lysis by viruses. Every organism in the biosphere is probably infected by at least one virus, but the most common viruses are thought to be those that infect bacteria. Viruses come in many varieties, but the simplest is a form of nucleic acid wrapped in a protein coat. The form of nucleic acid can be virtually any type of RNA or DNA, single or double stranded. Few viruses in nature can be identified by traditional methods because their hosts cannot be grown in the laboratory. Direct count methods have found that viruses are very abundant, being about ten-fold more abundant than bacteria, but the ratio of viruses to bacteria varies greatly. Viruses are thought to account for about 50% of bacterial mortality but the percentage varies from zero to 100%, depending on the environment and time. In addition to viruses of bacteria and cyanobacteria, microbial ecologists have examined viruses of algae and the possibility that viral lysis ends phytoplankton blooms. Viruses infecting fungi do not appear to lyse their host and are transmitted from one fungus to another without being released into the external environment. While viral lysis and grazing are both top-down controls on microbial growth, they differ in several crucial respects. Unlike grazers, which often completely oxidize prey organic material to carbon dioxide and inorganic nutrients, viral lysis releases the organic material from hosts more or less without modification. Perhaps even more important, viruses may facilitate the exchange of genetic material from one host to another. Metagenomic approaches have been used to explore viral diversity and the dynamics of virus communities in natural environments.

The focus of this chapter is an examination of the diversity of living organisms found within urban environments, both inside and outside buildings. The discussion commences with prions and viruses before moving on to consider micro-organisms, plants, and animals. Prions and viruses cause disease in plants and animals, including humans. Micro-organisms are ubiquitous and are found in great numbers throughout urban environments. New technologies are providing new insights into their diversity. Plants may be found inside buildings as well as in gardens and other green spaces. The final sections of the chapter offer a discussion of the diversity of animals that live in urban areas for part or all of their life cycle. Examples of the diversity of life in urban environments are presented throughout, including native and non-native species, those that are benign and deadly, and the common and the rare.

Hand washing is the main subject of this chapter. The importance of hand hygiene cannot be too strongly emphasized. How infections occur and the chain of infection are described. Important organisms such as HIV/AIDS, tuberculosis, vancomycin-resistant Enterococcus (VRE), methicillin-resistant Staphylococcus aureus (MRSA), and hepatitis viruses are all included. What to do about needlestick injuries, using the N95 mask, and information about recent advances in hand hygiene using alcohol are all to be found here.

This book consists of stories about what the foreigners living in China saw during the epidemic. In the book, the authors describe the situation of the epidemic and the dedication of the government and front-line medical personnel from their perspectives. They expressed the thoughts of shared human future with simplest and warmest words. This book aims to show the public an objective and true situation of China’s fight against COVID-19. This book is published jointly by Global Century Press (GCP) and Jiangxi Education Publishing House (JXEPH). GCP is a UK-based publisher dedicated to publishing social scientific and humanities academic and popular books bilingually in a global context. Founded in 1985, JXEPH is one of China’s leading education publishing houses. JXEPH is familiar to millions through a diverse publishing program that includes scholarly works in all academic disciplines, school and college textbooks, workbooks, materials for teaching Chinese as a foreign language, dictionaries and reference books, literary works, children’s books and periodicals.

Pests, Diseases and Beneficials helps gardeners to identify and deal with those common insects and small animals (such as bugs, beetles, caterpillars, thrips and mites) that are found in every Australian garden.
 It offers clear descriptions and full colour images to aid in identifying insects or other organisms, and provides useful advice on how to recognise and treat problems. The book also covers feeding habits, life cycles and insect biology.
 Based on the 1980 book Friends and Foes of Australian Gardens, this new work has been revised and expanded to include general garden situations as well as Australian native plants, and provides further information on plant diseases, harmless and beneficial fungi, bacteria and viruses, physiological disorders and problems caused by horticultural mismanagement.

Bacteria are the most frequent causes of severe sepsis and septic shock, while viruses, fungi, and parasites are implicated less often. Positive cultures are found in only 60% of cases; this may be the result of previous antibiotic therapy or inadequate sampling or testing. The etiology of sepsis is constantly changing; whereas Gram-negative organisms used to make up the majority of cases, Gram-positive bacteria now predominate. Sepsis due to fungal disease has also seen a dramatic rise. These changes may be explained by alterations in patient demographics, such as an increasingly elderly population with multiple comorbidities; an increased frequency of indwelling catheters or devices; and greater numbers of patients with immunosuppression as a result of disease or drug therapy. This chapter covers symptoms, demographics, diagnosis, investigation, prognosis, and treatment within the ITU environment.

Community structure refers to the taxonomic types of microbes and their relative abundance in an environment. This chapter focuses on bacteria with a few words about fungi; protists and viruses are discussed in Chapters 9 and 10. Traditional methods for identifying microbes rely on biochemical testing of phenotype observable in the laboratory. Even for cultivated microbes and larger organisms, the traditional, phenotype approach has been replaced by comparing sequences of specific genes, those for 16S rRNA (archaea and bacteria) or 18S rRNA (microbial eukaryotes). Cultivation-independent approaches based on 16S rRNA gene sequencing have revealed that natural microbial communities have a few abundant types and many rare ones. These organisms differ substantially from those that can be grown in the laboratory using cultivation-dependent approaches. The abundant types of microbes found in soils, freshwater lakes, and oceans all differ. Once thought to be confined to extreme habitats, Archaea are now known to occur everywhere, but are particularly abundant in the deep ocean, where they make up as much as 50% of the total microbial abundance. Dispersal of bacteria and other small microbes is thought to be easy, leading to the Bass Becking hypothesis that “everything is everywhere, but the environment selects.” Among several factors known to affect community structure, salinity and temperature are very important, as is pH especially in soils. In addition to bottom-up factors, both top-down factors, grazing and viral lysis, also shape community structure. According to the Kill the Winner hypothesis, viruses select for fast-growing types, allowing slower growing defensive specialists to survive. Cultivation-independent approaches indicate that fungi are more diverse than previously appreciated, but they are less diverse than bacteria, especially in aquatic habitats. The community structure of fungi is affected by many of the same factors shaping bacterial community structure, but the dispersal of fungi is more limited than that of bacteria. The chapter ends with a discussion about the relationship between community structure and biogeochemical processes. The value of community structure information varies with the process and the degree of metabolic redundancy among the community members for the process.

Primary liver cancer is one of the most commonly occurring cancers globally, and is the second most common cause of cancer death worldwide. There are two major histologic forms of primary liver cancer: hepatocellular carcinoma (HCC) and cholangiocarcinoma. It is a rapidly and almost uniformly fatal disease, yet there is already sufficient knowledge about its major risk factors, many of which are modifiable, to make primary prevention effective. Primary liver cancer is one of the first common human cancer that was found to have an infectious etiology, with hepatitis B virus (HBV) and hepatitis C virus (HCV) for HCC, and parasitic liver flukes for cholangiocarcinoma. Obesity is emerging as an important risk factor, particularly in Western countries, where primary liver cancer rates appear to be increasing over time. A number of additional risk factors and potential preventive factors are considered in this chapter.

HIV-1 originated in the early 1920s in southern Cameroon and the Democratic Republic of Congo. From Africa, HIV rapidly spread in the late 1960s to the Caribbean and then the United States, Europe, and other areas of the world, leading to the global AIDS pandemic. Both HIV-1 and HIV-2 descended genetically from Simian immunodeficiency virus via cross-species transmission. HIV-1 group M was the first lineage discovered and represents the pandemic form of the virus. Group M consists of nine viral subtypes (A–K), has a widespread distribution, and accounts for approximately 95% of all HIV-1 infections. HIV-2 was not discovered until 1986 and makes up approximately 3% of cases worldwide. It is found mainly in West Africa. The genetic diversity of HIV does not appear to significantly affect viral response to antiretroviral therapy. However, viral diversity continues to present challenges for the development of an effective HIV vaccine.