Post‐zygotic hybrid viability in sympatric species pairs: a case study from European lampreys

Ecological speciation mechanisms are widely assumed to play an important role in the early stages of divergence between incipient species, and this especially true of fishes. In the present study, we tested explicitly for post‐zygotic barriers to gene flow between a sympatric, recently diverged lamprey species pair that likely arose through ecological divergence. Experimental in vitro hybridization between anadromous parasitic Lampetra fluviatilis and resident nonparasitic Lampetra planeri resulted in a high proportion of embryos capable of attaining the burrowing pro‐larval stage, strongly indicating no post‐zygotic barriers to gene flow between these species. A sympatric, locally‐adapted resident parasitic form of L. fluviatilis was also found to successfully hybridize with both members of this species pair. The consequences of these findings are discussed in the context of lamprey speciation. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 108 , 378–383.     

Suppression dampens unpleasant emotion faster than reappraisal:Neural dynamics in a Chinese sample

The timing dynamics of regulating negative emotion with expressive suppression and cognitive reappraisal were investigated in a Chinese sample. Event-Related Potentials were recorded while subjects were required to view, suppress emotion expression to, or reappraise emotional pictures. The results showed a similar reduction in self-reported negative emotion during both strategies. Additionally, expressive suppression elicited larger amplitudes than reappraisal in central-frontal P3 component(340–480 ms). More importantly, the Late Positive Potential(LPP) amplitudes were decreased in each 200 ms of the 800–1600 ms time intervals during suppression vs. viewing conditions. In contrast, LPP amplitudes were similar for reappraisal and viewing conditions in all the time windows, except for the decreased amplitudes during reappraisal in the 1400–1600 ms. The LPP(but not P3) amplitudes were positively related to negative mood ratings, whereas the amplitudes of P3, rather than LPP, predict self-reported expressive suppression. These results suggest that expressive suppression decreases emotion responding more rapidly than reappraisal, at the cost of greater cognitive resource involvements in Chinese individuals.     

Lipolysis: more than just a lipase

Successful adaptation to starvation in mammals depends heavily on the regulated mobilization of fatty acids from triacylglycerols stored in adipose tissue. Although it has long been recognized that cyclic AMP represents the critical second messenger and hormone-sensitive lipase (HSL)**Abbreviations used in this paper: ADRP, adipocyte differentiation-related protein; HSL, hormone-sensitive lipase; PKA, protein kinase A; TAG, triacylglycerol. the rate-determining enzyme for lipolysis, simple activation of the enzyme has failed to account for the robust augmentation of fatty release in response to physiological agonists. In this issue, Sztalryd et al. (2003) provide convincing support to the notion that the subcellular compartmentalization of lipase also regulates lipolysis, and, more importantly, that proteins other than HSL are localized to the lipid droplet and are indispensable for its optimal hydrolysis.     

Mitochondria: more than just a powerhouse

Pioneering biochemical studies have long forged the concept that the mitochondria are the 'energy powerhouse of the cell'. These studies, combined with the unique evolutionary origin of the mitochondria, led the way to decades of research focusing on the organelle as an essential, yet independent, functional component of the cell. Recently, however, our conceptual view of this isolated organelle has been profoundly altered with the discovery that mitochondria function within an integrated reticulum that is continually remodeled by both fusion and fission events. The identification of a number of proteins that regulate these activities is beginning to provide mechanistic details of mitochondrial membrane remodeling. However, the broader question remains regarding the underlying purpose of mitochondrial dynamics and the translation of these morphological transitions into altered functional output. One hypothesis has been that mitochondrial respiration and metabolism may be spatially and temporally regulated by the architecture and positioning of the organelle. Recent evidence supports and expands this idea by demonstrating that mitochondria are an integral part of multiple cell signaling cascades. Interestingly, proteins such as GTPases, kinases and phosphatases are involved in bi-directional communication between the mitochondrial reticulum and the rest of the cell. These proteins link mitochondrial function and dynamics to the regulation of metabolism, cell-cycle control, development, antiviral responses and cell death. In this review we will highlight the emerging evidence that provides molecular definition to mitochondria as a central platform in the execution of diverse cellular events.     

Ki-67: more than a proliferation marker

Ki-67 protein has been widely used as a proliferation marker for human tumor cells for decades. In recent studies, multiple molecular functions of this large protein have become better understood. Ki-67 has roles in both interphase and mitotic cells, and its cellular distribution dramatically changes during cell cycle progression. These localizations correlate with distinct functions. For example, during interphase, Ki-67 is required for normal cellular distribution of heterochromatin antigens and for the nucleolar association of heterochromatin. During mitosis, Ki-67 is essential for formation of the perichromosomal layer (PCL), a ribonucleoprotein sheath coating the condensed chromosomes. In this structure, Ki-67 acts to prevent aggregation of mitotic chromosomes. Here, we present an overview of functional roles of Ki-67 across the cell cycle and also describe recent experiments that clarify its role in regulating cell cycle progression in human cells.     

Dioecy,more than monoecy,affects plant spatial genetic structure: the case study of Ficus

In this analysis, we attempt to understand how monoecy and dioecy drive spatial genetic structure (SGS) in plant populations. For this purpose, plants of the genus Ficus were used as a comparative model due to their particular characteristics, including high species diversity, variation in life histories, and sexual systems. One of the main issues we assessed is whether dioecious fig tree populations are more spatially genetically structured than monoecious populations. Using the Sp statistic, which allows for quantitative comparisons among different studies, we compared the extent of SGS between monoecious and dioecious Ficus species. To broaden our conclusions we used published data on an additional 27 monoecious and dioecious plant species. Furthermore, genetic diversity analyses were performed for two monoecious Ficus species using 12 microsatellite markers in order to strengthen our conclusions about SGS. Our results show that dioecy, more than monoecy, significantly contributes to SGS in plant populations. On average, the estimate of Sp was six times higher for dioecious Ficus species than monoecious Ficus species and it was two times higher in dioecious than monoecious plant species. Considering these results, we emphasize that the long‐distance pollen dispersal mechanism in monoecious Ficus species seems to be the dominant factor in determining weak spatial genetic structure, high levels of genetic diversity, and lack of inbreeding. Although Ficus constitute a model species to study SGS, a more general comparison encompassing a wider range of plants is required in order to better understand how sexual systems affect genetic structure.     

Quantifying cultural macro-evolution: a case study of the hinoeuma fertility drop

Understanding patterns and underlying processes of human cultural diversity has been a major challenge in evolutionary anthropology. Recent developments in the study of cultural macro-evolution have illuminated various novel aspects of cultural phenomena at the population level. However, limitations in data availability have constrained previous analyses to use simplest models ignoring factors that potentially affect cultural evolutionary dynamics. Here, we focus on two such factors: accumulated effects of cultural transmission between populations over time and variation in social influence among populations. As a test case, we analyze data on the hinoeuma fertility drop, the Japanese nation-wide drastic decline in the number of births caused by a culturally-transmitted superstition recurring every sixty years, to show that these factors do play significant roles. Specifically, our results suggest that transmission of the superstition in a short timescale has tended to occur among neighboring populations, while transmission in a long timescale is likely to have occurred between populations culturally close to each other, with the cultural closeness being measured by similarity in dialects. The results also indicate a special role played by a population occupying a center in a language–distance network (the cultural center) in the spread of the superstition.     

The COP9 signalosome: more than a protease

The COP9 signalosome (CSN) is a conserved protein complex that functions in the ubiquitin-proteasome pathway. After two decades of research, we now know that the CSN is a multi-subunit protease that regulates the activity of cullin-RING ligase (CRL) families of ubiquitin E3 complexes. The CSN is rapidly emerging as a key player in the DNA-damage response, cell-cycle control and gene expression. The independent functions of CSN5 (also known as JAB1) add to the complexity of the CSN machinery. Here, we provide an updated view of the structure, functions and regulation of this protein complex.     

Dimethylfumarate for psoriasis: more than a dietary curiosity

Fumaric acid esters (FAEs) have been used for the oral treatment of psoriasis since 1959 and have been registered for this indication in Germany since 1994. Dimethylfumarate (DMF) and its metabolite methylhydrogenfumarate (MHF) are the pharmacologically active compounds, with DMF being the main component of the marketed FAE-mixture. However, the mechanism of action of FAE is yet to be fully understood. It has been shown that DMF inhibits NFkappaB translocation, which leads to (i) the inhibition of pro-inflammatory cytokine production and adhesion molecule expression, (ii) the inhibition of dendritic cell differentiation and, at higher concentrations, (iii) the induction of apoptosis. Recent evidence also shows that these effects are mediated through the interference of the intracellular redox system by DMF. Here, the mode of action of FAE and its clinical use for psoriasis will be discussed.     

Legume genomes: more than peas in a pod

A growing array of sequence-based tools is helping to reveal the organization, evolution and syntenic relationships of legume genomes. The results indicate that legumes form a coherent taxonomic group with frequent and widespread macro- and microsynteny. This is good news for two model legume systems, Medicago truncatula and Lotus japonicus. Indeed, both models have recently been used to clone and characterize genes for nodulation-related receptors that were originally described in legumes with more complex genomes. Studies of legume genomes have also provided insight into genome size, gene clustering, genome duplications and repetitive elements. To understand legume genomes better, it will be necessary to develop tools for studying under-represented taxa beyond the relatively small group of economically important species that have been examined so far.