Pollen stigma interactions: so near yet so far

Getting a firm grip on the 'S' (incompatibility)-loci, which encourage outbreeding in many flowering plants, continues to be a frustrating exercise. Only last year it seemed that all the male and female S-locus factors that regulate self-incompatibility in a key group of plants - Brassica - had at last been characterized. However, it now appears that the first S-locus product to be identified, does not, after all, play a part in determining S-specificity.     

Drosophila Melanogaster, Drosophila Simulans: so Similar yet so Different

During the last two decades, the two cosmopolitan species Drosophila melanogaster and Drosophila simulans have been compared with regard to numerous characteristics, ranging from their geographic distribution and ecology to their DNA polymorphism. Various traits have been compared, including morphology, physiology, sexual behavior, allozymes and other proteins, chromosomal inversions, mitochondrial and nuclear DNA, transposable elements, wolbachia etc. Such comparisons reveal similarities and differences between the two species, depending on the trait considered. In most cases, the between-population variability of D. simulans is lower than that of D. melanogaster, but the two species exhibit similar levels of within-population variability. One of the main exceptions is the nucleotide polymorphism of several nuclear regions. Although several hypotheses have been proposed to explain these observations, the evolutionary dynamics of these two species are far from being understood. How have two species sharing a common ancestor in the recent past accumulated so many differences? A brief history of comparisons of the two species, from the first in 1919 by A.H. Sturtevant, and a summary of the hypotheses proposed to explain the similarities and the differences between these species are presented and discussed.     

Podosome-type adhesions and focal adhesions, so alike yet so different

Cell-matrix adhesions are essential for cell migration, tissue organization and differentiation, therefore playing central roles in embryonic development, remodeling and homeostasis of tissues and organs. Matrix adhesion-dependent signals cooperate with other pathways to regulate biological functions such as cell survival, cell proliferation, wound healing, and tumorigenesis. Cell migration and invasion are integrated processes requiring the continuous, coordinated assembly and disassembly of integrin-mediated adhesions. An understanding of how integrins regulate cell migration and invasiveness through the dynamic regulation of adhesions is fundamental to both physiological and pathological situations. A variety of cell-matrix adhesions has been identified, namely, focal complexes, focal adhesions, fibrillar adhesions, podosomes, and invadopodia (podosome-type adhesions). These adhesion sites contain integrin clusters able to develop specialized structures, which are different in their architecture and dynamics although they share almost the same proteins. Here we compare recent advances and developments in the elucidation of the organization and dynamics of focal adhesions and podosome-type adhesions, in order to understand how such subcellular sites - though closely related in their composition - can be structurally and functionally different. The underlying question is how their respective physiological or pathological roles are related to their distinct organization.     

TRAIL- and TNF-induced signaling complexes—so similar yet so different

TNF receptor-1 (TNFR1) and TRAIL death receptors preferentially induce pro-inflammatory or cytotoxic signaling, respectively, via distinct plasma membrane and cytosolic complexes. New studies identifying the pro-inflammatory factors TRAF2, RIP, and LUBAC in TRAIL death receptor complexes suggest that the latter are more “TNFR1-like” than anticipated and argue for revision of prevailing models of spatio-hierarchical TRAIL-induced signaling complex assembly.     

Allocating individuals to avoid inbreeding in ex situ conservation plantations: so far, so good

The only cost-effective way to control inbreeding in ex situ forest tree plantations is often to allocate trees in such a way that the possibility of close relatives mating is small and, consequently, inbreeding does not increase too much over time. The classical permutated neighbourhood methods look for the configuration in which no ramets of the same genet are planted in the surroundings (neighbourhoods) of a particular tree but deny the influence of more distant trees. Another limitation of these methods is that they cannot incorporate any other genetic (e.g. kinship) or ecological (e.g. phenology) information. We have developed a new method based on the minimisation of the global probability of generating inbred offspring for the whole population. Improvements of this method from the classical ones are: (i) it takes into account all the trees (whether near or far) and not only the neighbours; (ii) different pollen dispersal functions can be implemented, fitting the particularities of each species and population; (iii) it allows for the integration of all available information about the genetic relationship between trees; and (iv) it is flexible allowing for particular crosses to be banned or encouraged. The novel method showed a better performance than classical ones both for simulated data and a case study under a broad range of scenarios. Magnitude of the benefit depends on the actual and assumed parameters for the pollen dispersal function and the relationship between trees, but even in the simple case where only clone identity is considered some advantage can be obtained by implementing the new algorithm.     

Morels: the story so far

True morels, among the most glamorous and highly valued edible fungi, have been in the midst of taxonomical controversies for over a century. The use of molecular phylogenetic techniques and integrative taxonomical approaches have in recent years revolutionised our understanding of morels, resolving many of the old debates, but also giving rise to new ones. This review summarises the advances made and challenges met, with regards to this fascinating genus.