Virulence or Niche Factors: What's in a Name?

The increasing interest in the human microbiota raises some interesting questions about the terminology we use to describe some of the structures and strategies employed by commensal and pathogenic microbes to compete in these complex biological ecosystems. For example, all microbes arriving in the alimentary tract face the task of surviving passage through the stomach, coping with bile, interacting with the immune system, competing with the established microbiota, and obtaining sufficient nutrients to gain a foothold in this hostile environment. It is not surprising then that many gastrointestinal microbes (both pathogens and commensals) use similar strategies to overcome the challenges associated with this particular biological niche. Given that many of these structures and strategies were discovered and characterized in pathogens and because they often play important roles in establishing and maintaining an infection, they have often been characterized as virulence factors. It would be misleading to describe the same strategies and structures found in harmless commensals as “virulence factors,” since they represent a sine qua non for life in the gastrointestinal tract. It may be time to reconsider and refer to them as “niche factors,” both in terms of providing scientific accuracy but also in light of the growing interest in using gut microbes as probiotics, where the distinction between virulence factors and niche factors is likely to be very important from a regulatory perspective.     

RadC,a Misleading Name?

The pfam04002 annotation describes RadC as a bacterial DNA repair protein. Although the radC gene is expressed specifically during competence for genetic transformation in Streptococcus pneumoniae, we report that radC mutants exhibit normal uptake and processing of transforming DNA. They also display normal sensitivity to DNA-damaging agents, providing no support for the rad epithet.     

What's in a Name? Death before birth

The medical, legal, and lay communities utilize a range of words to describe a pregnancy that does not result in live birth. These terms, including abortion, miscarriage, and stillbirth, are more than just words: they carry with them a range of meanings and social consequences. This paper explores the complex implications embodied in the language used to designate fetal death and describes how they simultaneously, and paradoxically, establish conflicting subject positions for mother and fetus. It also examines the statutory regulations that affirm the problematic terms in a manner that may leave grieving families without ritual outlets for the expression of their loss. This paper draws on specific examples from Aotearoa New Zealand, while recognizing similarities across Western cultures.     

Lake Name or Name Lake? The etymology of lake nomenclature in the United States

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Potato Glycoalkaloids: A Burden or a Blessing?

Steroidal glycoalkaloids (SGAs) are produced following the general steroid biosynthesis pathway, starting from acetyl-coenzyme A and followed by the intermediates mevalonic acid, squalene, cycloartenol, and cholesterol. α-Chaconine and α-solanine are the main SGAs of the cultivated potato (Solanum tuberosum), whereas many other SGAs are known in the wild potato species. Low concentrations of SGAs improve the taste of potato, but concentrations greater than 200 mg/kg can have toxic effects on animals and humans. SGAs have antimicrobial activity and confer resistance to some insects, but many such pests of potato are not greatly affected. Certain environmental conditions and wounding enhance SGA accumulation in tubers in the field and storage. Low production of SGAs is a dominant character inherited in a relatively simple manner and can be selected for in potato-breeding programs, whereas the use of wild potato germplasm tends to increase the SGA accumulation in the breeding lines. Further efforts are likely to be directed toward the reduction of the SGA content in the edible potato products through breeding and biotechnological methodologies, whereas potato genotypes with high SGA production may be developed for use in the pharmaceutical industry.     

Homology: A comparative or a historical concept?

The meaning of the word homology has changed. From being a comparative concept in pre-Darwinian times, it became a historical concept, strictly signifying a common evolutionary origin for either anatomical structures or genes. This historical understanding of homology is not useful in classification; therefore I propose a return to its pre-Darwinian meaning.     

Record Chromosome Number in a Mammal?

CROSS has reported^{1, 2} chromosome complements in rodents ranging up to 2n=84 (in the North American geomyid Geomys breviceps) and 2n=86 (in the heteromyid Dipodomys merriami). Matthey has contested³ this claim; he maintained that in Geomys bursarius 2n =70 or 72 and he doubted whether a higher number had been confirmed. Numbers in the 2n=70 to 80 range have since been reported⁴ in several genera of Canidae and Ursidae. In general, rodent chromosomes fall into the lower group numbers but, among murines, Lophuromys aquillus is reported to have a chromosome complement of 70 (ref. 5) and Cricetomys gambianus one of 78 (ref, 6). In the gerbilline, Meriones shawii, the number can vary up to 78 (ref. 7).     

Bao-yu: A Mental Disorder or a Cultural Icon?

The embodied human subject is dynamically connected to his or her historico-sociocultural context, the soil from which a person’s psyche is nourished as multiplex meanings are absorbed and enable personal development. In each culture certain towering artistic works embody this perspective. The Dream of the Red Chamber introduces Jia Bao-yu—a scion of the prestigious Jia family—and his relationships with a large cast of characters. Bao-yu is controversial but, at the time of the family’s tragic collapse, he can be seen as embodying a spiritual struggle in which his instinct, nature, sensitivity, and creativity are grounded in his transcendent relationship with a fragment of the world stone, an eternal source of energy and creativity. We are invited to draw on a metaphysical level of thought to consider his struggles with man-made hierarchies and a situated historico-sociocultural order in such a way as to live out his spiritual being. As such, the novel is closely relevant to questions of spirituality in bioethics. Through personal experiences, passions, creativity, and relationships with others, the body is inscribed, forming the soul, which may be misconstrued (for instance, through a medical or Cartesian reformulation of events) but which can be seen as the site of ethical and spiritual thought.     

S100A2 in cancerogenesis: a friend or a foe?

Owing to the exceptional intracellular distribution and the heterogeneous expression pattern during transformation and metastasis in various tumors, the EF-hand calcium-binding protein S100A2 attracts increasing attention. Unlike the majority of S100 proteins, S100A2 expression is downregulated in many cancers and the loss in nuclear expression has been associated with poor prognosis. On the other hand, S100A2 is upregulated in some cancers. This mini review highlights the general characteristics of S100A2 and discusses recent findings on its putative functional implication as a suppressor or promoter in cancerogenesis.     

Lutzomyia longipalpis in Brazil: a complex or a single species? A mini-review

Lutzomyia longipalpis is the main vector of Leishmania infantum chagasi, the causative agent of American visceral leishmaniasis (AVL). Although there is strong evidence that Lu. longipalpis is a species complex, not all data concerning populations from Brazil support this hypothesis. The issue is still somewhat controversial for this large part of Lu. longipalpis distribution range even though that it is the Latin American region contributing to most of the cases of AVL. In this mini-review we consider in detail the current data for the Brazilian populations and conclude that Lu. longipalpis is a complex of incipient vector species with a complexity similar to Anopheles gambiae s.s. in Africa.     

Accelerated nitrogen inputs — A new problem or a new perspective?

This paper considers whether new problems are arising in forest ecosystems due to increased levels of inorganic N deposition from the atmosphere, or whether there are no new problems, just a change of perception. Deposition of N has indeed increased. Wet deposition rates are reasonably quantified, but the rates of dry deposition to forests are largely unknown. Current transport and deposition models are probably under-estimating N deposition to forests. Consideration of possible effects of enhanced N deposition reveals with varying degrees of certainty that there may be effects due to high N in biomass, high uptake rates, leaching of nitrate and consequent acidification, and an overall increase in N availability. Forest ecosystems are not well-enough understood to set a critical load for N deposition, but enough is known to define some upper limits.     

Endocytosis: A Positive or a Negative Influence on Wnt Signalling?

Endocytosis, with subsequent targeting to lysosomes for degradation, is traditionally seen as a way for cells to terminate signalling. However, in a few instances, endocytosis has been demonstrated to contribute positively to signalling. Here we review recent work on the role of endocytosis in Wnt signalling. Biochemical evidence suggests that the branch of Wnt signalling that controls planar cell polarity (PCP) does require endocytosis, although how endocytosis of Frizzled receptors is translated into PCP in vivo remains unknown. With respect to the main signalling branch (called the canonical or beta-catenin pathway), the literature is divided as to whether endocytosis is required. Results of in vivo experiments are inconclusive because of the toxic side-effects of blocking endocytosis. Some results with cultured cells suggest the need for endocytosis in canonical signalling; however, it remains unclear whether the ligand-receptor complex must enter the cell by clathrin-mediated or caveolae-mediated endocytosis in order to signal. Means of specifically altering Wnt trafficking as well as of tracking the internalization route in different cell types are needed.