Molecular phylogeny of the Caryophyllaceae (Caryophyllales) inferred from chloroplast matK and nuclear rDNA ITS sequences

Caryophyllaceae is a principally holarctic family including around 2200 species often classified into the three subfamilies Alsinoideae, Caryophylloideae, and Paronychioideae. Complex and possibly homoplasious morphological characters within the family make taxa difficult to delimit and diagnose. To explore part of the morphological evolution within the family, we investigated the phylogeny of the Caryophyllaceae by means of analyzing plastid and nuclear sequence data with parsimony and Bayesian methods. We describe a mode of tracing a stable phylogenetic signal in ITS sequences, and a significant common signal is shared with the plastid data. Parsimony and Bayesian analyses yield some differences in tree resolution. None of the subfamilies appear monophyletic, but the monophyly of the Caryophylloideae is not contradicted. Alsinoideae are paraphyletic, with Arenaria subg. Eremogone and Minuartia subg. Spergella more closely related to the Caryophylloideae. There is strong support for the inclusion of Spergula-Spergularia in an Alsinoideae-Caryophylloideae clade. Putative synapomorphies for these groupings are twice as many stamens as number of sepals and a caryophyllad-type of embryogeny. Paronychioideae form a basal grade, where tribe Corrigioleae are sister to the rest of the family. Free styles and capsules with simple teeth are possibly plesiomorphic for the family.     

Gata3 is required for early morphogenesis and Fgf10 expression during otic development

Inner ear develops from an induced surface ectoderm placode that invaginates and closes to form the otic vesicle, which then undergoes a complex morphogenetic process to form the membranous labyrinth. Inner ear morphogenesis is severely affected in Gata3 deficient mouse embryos, but the onset and basis of the phenotype has not been known. We show here that Gata3 deficiency leads to severe and unique abnormalities during otic placode invagination. The invagination problems are accompanied often by the formation of a morphological boundary between the dorsal and ventral otic cup and by the precocious appearance of dorsal endolymphatic characteristics. In addition, the endolymphatic domain often detaches from the rest of the otic epithelium during epithelial closure. The expression of several cell adhesion mediating genes is altered in Gata3 deficient ears suggesting that Gata3 controls adhesion and morphogenetic movements in early otic epithelium. Inactivation of Gata3 leads also to a loss of Fgf10 expression in otic epithelium and auditory ganglion demonstrating that Gata3 is an important regulator of Fgf-signalling during otic development.     

A new series of pyridinyl-alkynes as antagonists of the metabotropic glutamate receptor 5 (mGluR5)

Synthesis and some structure-activity relationships for a new series of propargyl ethers as mGluR5 antagonists are reported.     

Fluctuating asymmetry in populations of British roe deer (Capreolus capreolus) following historical bottlenecks and founder events

The potential impact of population bottlenecks and founder events on genetic diversity and indirect measures of fitness (such as fluctuating asymmetry; FA) has important conservation implications. Here we take advantage of historical events that generated a remnant roe deer (Capreolus capreolus) population in the north of the British Isles that retained diversity, while populations in the south were apparently extirpated during the early mediaeval era. The southern population was later re-established from small founder populations of introduced European roe deer starting in the 19th century. We assess the impact of these events, using the northern remnant population as a reference, based on measures of FA at 16 bilateral cranial traits. Comparing the northern and southern populations we find evidence of differential impact on both the level of FA and the relationship between FA and levels of genetic diversity.     

Decadal cycling within long-lived carbon pools revealed by dual isotopic analysis of mineral-associated soil organic matter

Long-lived soil organic matter (SOM) pools are critical for the global carbon (C) cycle, but challenges in isolating such pools have inhibited understanding of their dynamics. We physically isolated particulate (>53 μm), silt-, and clay-sized organic matter from soils collected over two decades from a perennial C₃ grassland established on long-term agricultural soil with a predominantly C₄ isotopic signature. Silt- and clay-sized fractions were then subjected to a sequential chemical fractionation (acid hydrolysis followed by peroxide oxidation) to isolate long-lived C pools. We quantified ¹⁴C and the natural ¹³C isotopic label in the resulting fractions to identify and evaluate pools responsible for long-lived SOM. After removal of particulate organic matter (~14% of bulk soil C) sequential chemical treatment removed 80% of mineral-associated C. In all mineral-associated fractions, at least 55% of C₄-derived C was retained 32 years after the switch to C₃ inputs. However, C₃–C increased substantially beginning ~25 years after the switch. Radiocarbon-based turnover times ranged from roughly 1200–3000 years for chemically resistant mineral-associated pools, although some pools turned over faster under C₃ grassland than in a reference agricultural field, indicating that new material had entered some pools as early as 14 years after the vegetation switch. These findings provide further evidence that SOM chemistry does not always reflect SOM longevity and resistance to microbial decomposition. Even measureable SOM fractions that have extremely long mean turnover times (>1500 years) can have a substantial component that is dynamic over much shorter timescales.     

Experimental evidence for density-dependent reproductive output in a coral reef fish

We tested for density-dependent reproduction in a small coral reef fish using field manipulations of density and observational data. Males of the study species, the bridled goby (Coryphopterus glaucofraenum Gill), defend benthic nest sites, within which they spawn with females, and females can spawn repeatedly over an extended breeding season. In small areas, usually only a single male nested at any one time regardless of how many males were present, so the probability of nesting was inversely proportional to density. Nesting males were almost always the largest in the vicinity, suggesting that, for males whose home ranges overlap, social interactions dictate opportunities to nest. Both the per capita rate at which clutches were laid and the number of eggs produced per clutch declined with increasing density, so the per capita rate of egg production was also density dependent. All three measures of fecundity were better predicted by numerical density (numbers per unit area) than biomass (mass of fish per unit area), and were well described as an inverse function of the number of gobies in the vicinity. A simple hypothesis consistent with these results is that a constant number of females spawn, regardless of density. Alternately, the effect of crowding may depend primarily on the number of interacting individuals and affect all females relatively equally. This density dependence could thus contribute to population regulation at the spatial scale over which populations become reproductively closed.     

Deletion of SNAP-23 results in pre-implantation embryonic lethality in mice

SNARE-mediated membrane fusion is a pivotal event for a wide-variety of biological processes. SNAP-25, a neuron-specific SNARE protein, has been well-characterized and mouse embryos lacking Snap25 are viable. However, the phenotype of mice lacking SNAP-23, the ubiquitously expressed SNAP-25 homolog, remains unknown. To reveal the importance of SNAP-23 function in mouse development, we generated Snap23-null mice by homologous recombination. We were unable to obtain newborn SNAP-23-deficient mice, and analysis of pre-implantation embryos from Snap23(Δ/wt) matings revealed that Snap23-null blastocysts were dying prior to implantation at embryonic day E3.5. Thus these data reveal a critical role for SNAP-23 during embryogenesis.     

Controls on Soil Organic Carbon Stocks and Turnover Among North American Ecosystems

Despite efforts to understand the factors that determine soil organic carbon (SOC) stocks in terrestrial ecosystems, there remains little information on how SOC turnover time varies among ecosystems, and how SOC turnover time and C input, via plant production, differentially contribute to regional patterns of SOC stocks. In this study, we determined SOC stocks (gC m⁻²) and used soil radiocarbon measurements to derive mean SOC turnover time (years) for 0–10 cm mineral soil at ten sites across North America that included arctic tundra, northern boreal, northern and southern hardwood, subtropical, and tropical forests, tallgrass and shortgrass prairie, mountain grassland, and desert. SOC turnover time ranged 36-fold among ecosystems, and was much longer for cold tundra and northern boreal forest and dry desert (1277–2151 years) compared to other warmer and wetter habitats (59–353 years). Two measures of C input, net aboveground production (NAP), determined from the literature, and a radiocarbon-derived measure of C flowing to the 0–10 cm mineral pool, I, were positively and SOC turnover time was negatively associated with mean annual evapotranspiration (ET) among ecosystems. The best fit model generated from the independent variables NAP, I, annual mean temperature and precipitation, ET, and clay content revealed that SOC stock was best explained by the single variable I. Overall, these findings indicate the primary role that C input and the secondary role that C stabilization play in determining SOC stocks at large regional spatial scales and highlight the large vulnerability of the global SOC pool to climate change.     

Mortality of urban pines in Helsinki explored using tree rings and climate records

The mortality of Scots pine trees in and around Helsinki has been reported in recent years, but the causalities of these deaths have not so far been rigorously examined. Tree-ring analyses have previously shown to effectively reveal historical growth variability and thus hint at the stress factors behind tree mortality. Here, we analyzed the tree rings of pines in two tree classes (living and dead) from an urban park in Helsinki to reveal their growth variations and to examine the obtained chronologies along with climatic data. Guided by tree-ring information, the pine growth over the past century could be divided into four episodes: average growth conditions during the first half of the twentieth century, a suppressed growth period during the 1950s and 1960s, a growth release since the mid-1970s, and a period of recent mortality. The two tree classes became particularly differentiated during the release period in that the growth of surviving pines underwent a more positive and abrupt growth anomaly in comparison to dead pines. The survival of pines could also be linked to their sensitivity to droughts in a long-term context: The growth of still-living pines showed a statistically significant moisture sensitivity over the second half of the century only. The period 2002–2003 (coinciding with drought) was observed as a dendrochronologically dated episode with a 40% mortality. Overall, the results point to the importance of tree competitive strength and climate as predisposing and inciting/contributing factors behind the tree mortality.