DEEP WORK

In the previous chapter, viruses were defined as obligate intracellular parasites that are unable to direct any independent biosynthetic processes outside the host cell. It was further noted that the genetic complexity of viruses varies greatly between individual virus families, ranging from those viruses that encode only a few proteins to others that encode several hundred proteins. Given this ..

Bacteriophages (or phages) are now widely recognized to outnumber bacteria by an estimated tenfold1 . The remarkable diversity of phages is best illustrated by the frequency of novel genes that are found in newly characterized phage genomes2 . Such natural variation is a reflection of the array of bacterial hosts that are available to phages and the high evolution rate of phages when facing sele..

Box 1 | Phage life cycles and taxonomyThere is considerable diversity among phages, and both genomic and morphological information is currently used in their classification67,90. As we learn more about the diversity of phages and their genomic mosaicism, their taxonomy and classification require regular updating and have been said to be “as much an art as a science” (REF. 67). Initially, d’Hérel..

IntroductionEnveloped viruses introduce their genomes into host cells by membrane fusion. With paramyxoviruses, such as Sendai virus, fusion is independent of pH and can occur at the cell surface (see Poste & Pasternak, 1978). However, in other groups of enveloped viruses, including toga-, orthomyxoand rhabdoviruses, the fusion activity is triggered only in mildly acidic (pH 5-6) conditions (see..

Epidermal growth factor (EGF) was originally isolated from mouse salivary gland extract as a factor accelerating corneal wound healing (10). EGF now is recognized as a general growth factor that exerts various actions, including cell migration and proliferation, on a wide variety of cells (7, 43, 44). EGF stimulates the proliferation of keratinocytes in culture, and the topical administration of..

1. IntroductionThe nonpathogenic Escherichia coli strain Nissle 1917 (EcN) is among the most studied probiotic bacteria [1,2]. Over 100 years, EcN has been actively used as a pharmaceutical product (trade name: Mutaflor) for the treatment of intestinal disorders, such as inflammatory bowel disease, ulcerative colitis, and diarrhea [2]. EcN is a successful colonizer of the human gut, possessing s..

VIRAL INFECTIONS AND ANTIVIRAL AGENTSMany human diseases are due to viruses. These agents consist of genomes of either DNA or RNA inside a protein shell. Despite this deceptive simplicity, virus infections are less well understood than bacterial diseases, largely because viruses cannot be grown alone in culture but depend on a host cell. Until recently, protection against virus diseases relied o..

1. IntroductionSharpsnout sea bream, Diplodus puntazzo (Sparidae), is an increasingly cultured species in the Mediterranean area due to its high growth rate and food conversion efficiency [1,2]. Amongst the pathologies responsible for the high mortality rates observed in on-growing facilities, enteromyxosis due to Enteromyxum leei (formerly Myxidium leei) [3] accounts for important epizootic epi..

Most of what we know about bacteria derives from their growth. Their ability to propagate may be seen as a supreme achievement that enables them to attain enormous populations at rates that are breathtaking from a human perspective. These properties underpin their capacity for change by mutation and the rapidity with which some infections develop. Bacterial growth involves both an increase in th..

Micro-organisms are beyond doubt the most successful forms of life; they have been here longest, they are the most numerous and their distribution defines the limits of the biosphere, encompassing environments previously thought incapable of sustaining life. Here, we are concerned with the tiny fraction of microorganisms that form associations with human beings and these encompass the cellular e..