Recent star formation in clusters of galaxies: extreme compact starbursts in A539 and A634

We report on the detection of two Halpha-emitting extreme compact objects from deep images of the Abell 634 and Abell 539 clusters of galaxies at z ~ 0.03. Follow up long slit spectroscopy of these two unresolved sources revealed that they are members of their respective clusters showing HII type spectra. The luminosity and the extreme equivalent width of Halpha+[NII] measured for these sources, together with their very compact appearance, has raised the question about the origin of these intense starbursts in the cluster environment. We propose the compact starburst in Abell 539 resulted from the compression of the interstellar gas of a dwarf galaxy when entering the cluster core; while the starburst galaxy in Abell 634 is likely to be the result of a galaxy-galaxy interaction, illustrating the preprocessing of galaxies during their infall towards the central regions of clusters. The contribution of these compact star-forming dwarf galaxies to the star formation history of galaxy clusters is discussed, as well as a possible link with the recently discovered early-type ultra-compact dwarf galaxies. We note that these extreme objects will be rarely detected in normal magnitude-limited optical or NIR surveys, mainly due to their low stellar masses (of the order of 10^6 solar masses), whereas they will easily show up in dedicated Halpha surveys given the high equivalent width of their emission lines.Comment: Accepted for publication in the Astronomical Journal. 31 pages, 10 fig

An Autonomous Robotic System for Mapping Abandoned Mines

We present the software architecture of a robotic system for mapping abandoned mines. The software is capable of acquiring consistent 2D maps of large mines with many cycles, represented as Markov random fields. 3D C-space maps are acquired from local 3D range scans, which are used to identify navigable paths using A* search. Our system has been deployed in three abandoned mines, two of which inaccessible to people, where it has acquired maps of unprecedented detail and accuracy

The short-duration GRB 050724 host galaxy in the context of the long-duration GRB hosts

We report optical and near-infrared broad band observations of the short-duration GRB 050724 host galaxy, used to construct its spectral energy distribution (SED). Unlike the hosts of long-duration gamma-ray bursts (GRBs), which show younger stellar populations, the SED of the GRB 050724 host galaxy is optimally fitted with a synthetic elliptical galaxy template based on an evolved stellar population (age ~2.6 Gyr). The SED of the host is difficult to reproduce with non-evolving metallicity templates. In contrast, if the short GRB host galaxy metallicity enrichment is considered, the synthetic templates fit the observed SED satisfactorily. The internal host extinction is low (A_v \~< 0.4 mag) so it cannot explain the faintness of the afterglow. This short GRB host galaxy is more massive (~5x10^10 Mo) and luminous (~1.1 L*) than most of the long-duration GRB hosts. A statistical comparison based on the ages of short- and long-duration GRB host galaxies strongly suggests that short-duration GRB hosts contain, on average, older progenitors. These findings support a different origin for short- and long-duration GRBs.Comment: A&A in pres

Study of star formation in NGC 1084

We present UBVRI broad band, H$\alpha$ narrow band photometry of the star forming complexes in the infra-red bright galaxy NGC 1084. Results of medium resolution spectroscopy of some of the brighter complexes are also discussed. Spectroscopic data is used to better estimate the internal reddening within the galaxy which is found to be highly variable and to calculate metallicity which is close to the solar value. Diagnostic diagram identifies the shocked regions within this galaxy. The narrow band H$\alpha$ flux and its equivalent width are used to determine the star formation rates of the complexes and the distribution of ages. Star formation rates for a few of the complexes are found to be as high as 0.5 $M_{\odot}$/year. The star forming complexes lie in the age range 3 Myr to 6.5 Myr. U-B vs V-I colour-colour mixed population model created using the Starburst99 model colours is used to estimate the ages of the stellar populations present within these regions. Using this technique, it is found that the star formation in NGC 1084 has taken place in a series of short bursts over the last 40 Myr or so. It is proposed that the likely trigger for enhanced star formation is merger with a gas rich dwarf galaxy.Comment: 9 figures and 6 tables, Accepted in MNRAS for publicatio

Induced mutations in ASPARAGINE SYNTHETASE-A2 reduce free asparagine concentration in the wheat grain

Acrylamide is a neurotoxin and probable carcinogen formed as a processing contam-inant during baking and production of different foodstuffs, including bread products.The amino acid asparagine is the limiting substrate in the Maillard reaction thatproduces acrylamide, so developing wheat (Triticum aestivumL.) cultivars withlow free asparagine concentrations in the grain is a promising approach to reducedietary acrylamide exposure. A candidate gene approach was used to identify chemi-cally induced genetic variation inASPARAGINE SYNTHETASE 2(ASN2) genes thatexhibit a grain-specific expression profile. In field trials, durum and common wheatlines carryingasn-a2null alleles exhibited reductions in free asparagine concentra-tion in their grains of between 9 and 34% compared with wildtype sister lines. Theseplants showed no significant differences in spikelet number, grain size and weight,germination or baking quality traits. These nontransgenic variants can be deployedwithout regulatory oversight in elite wheat germplasm to reduce acrylamide-formingpotential with no negative effects on quality or agronomic performance

Multi-target genome editing reduces polyphenol oxidase activity in wheat (Triticum aestivum L.) grains

Introduction: Polyphenol oxidases (PPO) are dual activity metalloenzymes that catalyse the production of quinones. In plants, PPO activity may contribute to biotic stress resistance and secondary metabolism but is undesirable for food producers because it causes the discolouration and changes in flavour profiles of products during post-harvest processing. In wheat (Triticum aestivum L.), PPO released from the aleurone layer of the grain during milling results in the discolouration of flour, dough, and end-use products, reducing their value. Loss-of-function mutations in the PPO1 and PPO2 paralogous genes on homoeologous group 2 chromosomes confer reduced PPO activity in the wheat grain. However, limited natural variation and the proximity of these genes complicates the selection of extremely low-PPO wheat varieties by recombination. The goal of the current study was to edit all copies of PPO1 and PPO2 to drive extreme reductions in PPO grain activity in elite wheat varieties. Results: A CRISPR/Cas9 construct with one single guide RNA (sgRNA) targeting a conserved copper binding domain was used to edit all seven PPO1 and PPO2 genes in the spring wheat cultivar ‘Fielder’. Five of the seven edited T1 lines exhibited significant reductions in PPO activity, and T2 lines had PPO activity up to 86.7% lower than wild-type. The same construct was transformed into the elite winter wheat cultivars ‘Guardian’ and ‘Steamboat’, which have five PPO1 and PPO2 genes. In these varieties PPO activity was reduced by >90% in both T1 and T2 lines. In all three varieties, dough samples from edited lines exhibited reduced browning. Discussion: This study demonstrates that multi-target editing at late stages of variety development could complement selection for beneficial alleles in cropbreeding programs by inducing novel variation in loci inaccessible to recombinatio

Reduced free asparagine in wheat grain resulting from a natural deletion of TaASNB2: investigating and exploiting diversity in the asparagine synthetase gene family to improve wheat quality

Background: Understanding the determinants of free asparagine concentration in wheat grain is necessary to reduce levels of the processing contaminant acrylamide in baked and toasted wheat products. Although crop management strategies can help reduce asparagine levels, breeders have limited options to select for genetic variation underlying this trait. Asparagine synthetase enzymes catalyse a critical step in asparagine biosynthesis in plants and, in wheat, are encoded by five homeologous gene triads that exhibit distinct expression profiles. Within this family, TaASN2 genes are highly expressed during grain development but TaASN-B2 is absent in some varieties. Results: Natural genetic diversity in the asparagine synthetase gene family was assessed in different wheat varieties revealing instances of presence/absence variation and other polymorphisms, including some predicted to affect the function of the encoded protein. The presence and absence of TaASN-B2 was determined across a range of UK and global common wheat varieties and related species, showing that the deletion encompassing this gene was already present in some wild emmer wheat genotypes. Expression profiling confirmed that TaASN2 transcripts were only detectable in the grain, while TaASN3.1 genes were highly expressed during the early stages of grain development. TaASN-A2 was the most highly expressed TaASN2 homeologue in most assayed wheat varieties. TaASN-B2 and TaASN-D2 were expressed at similar, lower levels in varieties possessing TaASN-B2. Expression of TaASN-A2 and TaASN-D2 did not increase to compensate for the absence of TaASN-B2, so total TaASN2 expression was lower in varieties lacking TaASN-B2. Consequently, free asparagine levels in field-produced grain were, on average, lower in varieties lacking TaASN-B2, although the effect was lost when free asparagine accumulated to very high levels as a result of sulphur deficiency. Conclusions: Selecting wheat genotypes lacking the TaASN-B2 gene may be a simple and rapid way for breeders to reduce free asparagine levels in commercial wheat grain

GIBBERELLIN 3-OXIDASE genes regulate height and grain size in bread wheat

In plants, gibberellin (GA) levels are tightly regulated to optimise growth and development. GA 3-oxidases (GA3OX) catalyse a key GA biosynthesis step, converting precursor GAs into bioactive forms. We characterised seven GA3OX homologues in bread wheat (Triticum aestivum L.): a homoeologous triad of GA3OX2 genes expressed in vegetative and reproductive tissues and four others (a homoeologous triad of GA3OX3 genes plus GA1OX1-B1) expressed predominantly in grains. ga3ox2 mutants are severely dwarfed and infertile due to very low bioactive GA levels, indicating GA3OX2 is essential for normal wheat development. By contrast, ga3ox3 mutants have lower bioactive GA levels in grains, reducing grain size and weight, while ga1ox1 mutants accumulate high levels of bioactive GAs, producing larger grains. Unexpectedly, ga3ox3 and ga1ox1 alleles also affected height, possibly reflecting GA transport to vegetative tissues. Natural variation in adjacent GA3OX3-B1 and GA1OX1-B1 genes was associated with differences in grain size and weight, suggesting that a haplotype associated with larger grains was selected during modern breeding. Our study shows that the wheat GA3OX family has diversified roles, with GA3OX2 required for general growth and GA3OX3/GA1OX1 modulating GA levels during grain development. These findings highlight opportunities to exploit variation in GA biosynthetic pathways for wheat improvement

'Farming with Alternative Pollinators' approach increases pollinator abundance and diversity in faba bean fields

peer reviewedPollinators are threatened worldwide and strategies and measures to support their conservation are proliferating. Among them, the approach 'Farming with Alternative Pollinators' (FAP) aims to support pollinators by seeding strips of pollinatorattracting cultivated plants surrounding the crops, and simultaneously providing income to the farmer. In this study we assessed whether this approach supports pollinator diversity in agro-ecosystems and increases flower visitor diversity and abundance in faba bean fields in north-west Morocco. We tested the impact of FAP using a variety of marketable habitat enhancement plants (MHEP): flax, coriander, arugula, chia and canola. A total of 62 pollinator species were recorded, among which almost half of them are new records for the region. Most wild pollinators recorded in faba bean were digger bees (genus Anthophora) and long-horn bees (genus Eucera). MHEP shared diverse flower visitors with faba bean and hosted diverse pollinator groups that did not meet their food requirements from the main crop. The FAP approach highly increased flower visitor abundance and diversity in the whole FAP fields, however it did not generate significant pollinator spillover towards the main crop. Implications for insect conservation: our results show that the FAP approach is an effective approach to mitigate pollinator decline in agro-ecosystems.Contrat de prestation de service avec l'International Center for Agricultural Research in the DryAreas (ICARDA) - Sources publiques supra-européennes3. Good health and well-being15. Life on lan