Transdifferentiation: why and how?

Cell therapy is based on the replacement of damaged cells in order to restore injured tissues. The first consideration is that an abundant source of cells is needed; second, these cells should be immunologically compatible with the guest and third, there should be no real threat of these cells undergoing malignant transformation in the future. Given these requirements, already differentiated adult cells or adult stem cells obtained from the body of the patient appear to be the ideal candidates to meet all of these demands. The utilization of somatic cells also avoids numerous ethical and political drawbacks and concerns. Transdifferentiation is the phenomenon by which an adult differentiated cell switches to another differentiated cell. This paper reviews the importance of transdifferentiation, discussing the cells that are suitable for this process and the methods currently employed to induce the change in cell type.     

Cell-cycle-specific Golgi fragmentation: how and why?

The Golgi membranes, in the form of stacks of cisternae, are contained in the pericentriolar region of mammalian cells. During mitosis, these membranes are fragmented and dispersed throughout the cell. Recent studies are revealing the significance of pericentriolar position of the Golgi apparatus and mechanism by which these membranes are fragmented during mitosis.     

SNARE complexes and neuroexocytosis: how many, how close?

Regulated secretion is an essential process in all eukaryotic cells. The release of molecules contained inside exocytic granules and synaptic vesicles is mediated by the assembly of a SNARE complex formed by the coil-coiling of three proteins: SNAP-25, syntaxin and VAMP/synaptobrevin. It seems that SNARE complexes assemble together in rosette-shaped super-complexes but there is controversy on the actual number (N) of copies of SNARE complexes that are necessary to mediate exocytosis. We discuss attempts to determine the value of N and suggest that N varies with the type of exocytic vesicles. In addition, we propose that the N value in neuroexocytosis can be estimated by the comparative use of different types of botulinum neurotoxins.     

Calcium - how and why?

Calcium is among the most commonly used ions, in a multitude of biological functions, so much so that it is impossible to imagine life without calcium. In this article I have attempted to address the question as to how calcium has achieved this status with a brief mention of the history of calcium research in biology. It appears that during the origin and early evolution of life the Ca²⁺ ion was given a unique opportunity to be used in several biological processes because of its unusual physical and chemical properties.     

Anchoring proteins and cardiac sudden death: how and why?

Mutations in proteins responsible for ion transport in cardiac tissue can induce a destabilization of electrical function and provoke cardiac sudden death. Identification of a genetic anomaly in a French family that developed the syndrome of cardiac sudden death has revealed a crucial new element in normal cardiac electrical function : Ion channels need to be anchored to specific domains at the plasma membrane by an anchoring protein called ankyrin-B.     

Schistosome monogamy: who,how, and why?

Schistosomes represent a unique animal model for comparative analyses of monogamy. Indeed, schistosomes are classified at the lowest taxonomical level of monogamous species and lack complex social interactions, which could alter our understanding of their unusual mating system. Elements discussed here include the fact that monogamy in schistosomes could be an ancestral state between hermaphroditism and polygyny or polygynandry and the occurrence of mate changes. In addition, hypotheses are proposed to explain monogamy in schistosomes (e.g. female dispersion, the need for paternal care, oviposition site limitation or aggressiveness, and mate guarding). We also propose future experimental and analytical approaches to improve our understanding of the schistosomes' mating system.     

An ecological map of Europe: why and how?

After a recall of the recent emergence of the great ecological problems on the scale of the European continent and of the privileged use of vegetation maps as an ecological tool, a cartographic synthesis of the main plant formations in Europe is submitted on the basis of a hierarchized and numerized nomenclature of the vegetation units. Examples of connections between vegetation and ecology, as suggested or facilitated by this map, are given: use of the monthly ombrothermic diagrams as a privileged tool, thermic limits of the boreal zone, indicative value of the Mediterranean xerothermic area, predictive models of the geographical shifts of the great ecosystems according to the expected climate changes.     

Parasitic worms: how many really?

Accumulation curves are useful tools to estimate species diversity. Here we argue that they can also be used in the study of global parasite species richness. Although this basic idea is not completely new, our approach differs from the previous ones as it treats each host species as an independent sample. We show that randomly resampling host–parasite records from the existing databases makes it possible to empirically model the relationship between the number of investigated host species, and the corresponding number of parasite species retrieved from those hosts. This method was tested on 21 inclusive lists of parasitic worms occurring on vertebrate hosts. All of the obtained models conform well to a power law curve. These curves were then used to estimate global parasite species richness. Results obtained with the new method suggest that current predictions are likely to severely overestimate parasite diversity.     

Signalling sphingomyelinases: which, where, how and why?

A major lipid signalling pathway in mammalian cells implicates the activation of sphingomyelinase (SMase), which upon cell stimulation hydrolyses the ubiquitous sphingophospholipid sphingomyelin to ceramide. This review summarizes our current knowledge on the nature and regulation of signalling SMase(s). Because of the controversy on the identity of this(these) phospholipase(s), the roles of various SMases in cell signalling are discussed. Special attention is also given to the subcellular site of action of signalling SMases and to the cellular factors that positively or negatively control their activity. These regulating agents include lipids (arachidonic acid, diacylglycerol and ceramide), kinases, proteases, glutathione and other proteins.     

Apoptosis: why and how does it occur in biology?

The literature on apoptosis has grown tremendously in recent years, and the mechanisms that are involved in this programmed cell death pathway have been enlightened. It is now known that apoptosis takes place starting from early development to adult stage for the homeostasis of multicellular organisms, during disease development and in response to different stimuli in many different systems. In this review, we attempted to summarize the current knowledge on the circumstances and the mechanisms that lead to induction of apoptosis, while going over the molecular details of the modulator and mediators of apoptosis as well as drawing the lines between programmed and non-programmed cell death pathways. The review will particularly focus on Bcl-2 family proteins, the role of different caspases in the process of apoptosis, and their inhibitors as well as the importance of apoptosis during different disease states. Understanding the molecular mechanisms involved in apoptosis better will make a big impact on human diseases, particularly cancer, and its management in the clinics.     

Rabbit relinquishment through online classified advertisements in the United Kingdom: when,why, and how many?

To identify implicit causes of companion rabbit relinquishment, this study investigated whether there was annual and seasonal variation in the number of advertisements and ages of rabbits posted as free or for sale on classified websites in the United Kingdom. The number of advertisements posted decreased from 2014 to 2016. There was an increase in the number of advertisements for free rabbits in winter compared with other seasons, which could be a result of caregivers’ reduced willingness to interact with their rabbits and carry out husbandry during periods of inclement weather. Rabbits advertised as free were older than rabbits advertised for sale, and rabbits relinquished due to human-related reasons were older than those relinquished because of rabbit-related factors. It is recommended that further research is undertaken to elucidate whether providing education to prospective rabbit caregivers regarding the life span of rabbits and their substantial husbandry requirements, especially in winter, would deter the purchase of rabbits by caregivers unable or unwilling to care for them in the long term.