Genetic distance of inbred lines of Chinese cabbage and its relationship to heterosis

AbstractChinese cabbage (Brassica rapa L. var. pekinensis) is an important vegetable in Asia. Most Japanese commercial cultivars of Chinese cabbage use an F1 hybrid seed production system because of the high yielding cultivars produced. An efficient method for predicting hybrid performance in the parental generations is desired, and genetic distance between parental lines might be a good indicator of the level of hybrid vigor in a cross. Information concerning the genetic relationships among parental candidate inbred lines is useful for variety protection. The number of DNA markers available that can be used to assess the purity of inbred lines is limited in B. rapa. The aim of this study is to use DNA markers to assess the genetic distance between inbred lines to examine early developmental and yield heterosis so as to develop methods for selecting the best parental lines for the production of hybrids. We screened highly polymorphic SSR and CAPS markers to assess the genetic uniformity of inbred lines and characterize their genetic relationship. We examined the early size and yield heterosis in 32 F1 hybrids of Chinese cabbage. There was a moderate correlation in mid-parent heterosis between leaf size at 21days after sowing and harvested biomass but not in best-parent heterosis. In contrast there was no correlation between genetic distance and mid-parent or best-parent heterosis, indicating that genetic distance does not predict the heterosis phenotype

The Japanese space gravitational wave antenna; DECIGO

DECi-hertz Interferometer Gravitational wave Observatory (DECIGO) is the future Japanese space gravitational wave antenna. DECIGO is expected to open a new window of observation for gravitational wave astronomy especially between 0.1 Hz and 10 Hz, revealing various mysteries of the universe such as dark energy, formation mechanism of supermassive black holes, and inflation of the universe. The pre-conceptual design of DECIGO consists of three drag-free spacecraft, whose relative displacements are measured by a differential Fabry– Perot Michelson interferometer. We plan to launch two missions, DECIGO pathfinder and pre- DECIGO first and finally DECIGO in 2024

DECIGO pathfinder

DECIGO pathfinder (DPF) is a milestone satellite mission for DECIGO (DECi-hertz Interferometer Gravitational wave Observatory) which is a future space gravitational wave antenna. DECIGO is expected to provide us fruitful insights into the universe, in particular about dark energy, a formation mechanism of supermassive black holes, and the inflation of the universe. Since DECIGO will be an extremely large mission which will formed by three drag-free spacecraft with 1000m separation, it is significant to gain the technical feasibility of DECIGO before its planned launch in 2024. Thus, we are planning to launch two milestone missions: DPF and pre-DECIGO. The conceptual design and current status of the first milestone mission, DPF, are reviewed in this article

The naked truth:a comprehensive clarification and classification of current 'myths' in naked mole-rat biology

The naked mole-rat (Heterocephalus glaber) has fascinated zoologists for at least half a century. It has also generated considerable biomedical interest not only because of its extraordinary longevity, but also because of unusual protective features (e.g. its tolerance of variable oxygen availability), which may be pertinent to several human disease states, including ischemia/reperfusion injury and neurodegeneration. A recent article entitled 'Surprisingly long survival of premature conclusions about naked mole-rat biology' described 28 'myths' which, those authors claimed, are a 'perpetuation of beautiful, but falsified, hypotheses' and impede our understanding of this enigmatic mammal. Here, we re-examine each of these 'myths' based on evidence published in the scientific literature. Following Braude et al., we argue that these 'myths' fall into four main categories: (i) 'myths' that would be better described as oversimplifications, some of which persist solely in the popular press; (ii) 'myths' that are based on incomplete understanding, where more evidence is clearly needed; (iii) 'myths' where the accumulation of evidence over the years has led to a revision in interpretation, but where there is no significant disagreement among scientists currently working in the field; (iv) 'myths' where there is a genuine difference in opinion among active researchers, based on alternative interpretations of the available evidence. The term 'myth' is particularly inappropriate when applied to competing, evidence-based hypotheses, which form part of the normal evolution of scientific knowledge. Here, we provide a comprehensive critical review of naked mole-rat biology and attempt to clarify some of these misconceptions

The status of DECIGO

DECIGO (DECi-hertz Interferometer Gravitational wave Observatory) is the planned Japanese space gravitational wave antenna, aiming to detect gravitational waves from astrophysically and cosmologically significant sources mainly between 0.1 Hz and 10 Hz and thus to open a new window for gravitational wave astronomy and for the universe. DECIGO will consists of three drag-free spacecraft arranged in an equilateral triangle with 1000 km arm lengths whose relative displacements are measured by a differential Fabry-Perot interferometer, and four units of triangular Fabry-Perot interferometers are arranged on heliocentric orbit around the sun. DECIGO is vary ambitious mission, we plan to launch DECIGO in era of 2030s after precursor satellite mission, B-DECIGO. B-DECIGO is essentially smaller version of DECIGO: B-DECIGO consists of three spacecraft arranged in an triangle with 100 km arm lengths orbiting 2000 km above the surface of the earth. It is hoped that the launch date will be late 2020s for the present

Sea-ice-thickness variability in the Chukchi Sea, spring and summer 2002-2004

Measurements of sea ice thickness were obtained from drill holes, an ice-based electromagnetic induction instrument (IEM) and a ship-borne electromagnetic induction instrument (SEM) during the early melt season in the southern Chukchi Sea in 2002 and 2004, and in late summer 2003 at the time of minimum ice extent in the northern Chukchi Sea. An ice roughness criterion was applied to distinguish between level and rough or ridged ice. Ice thickness modes in the probability density functions (PDFs) derived from drill-hole and IEM measurements agreed well, with modes at 1.5-1.6 m and 1.8-1.9 m for all data from level ice. The PDFs derived from SEM measurements show that the primary modes are at 0.1 and 1.1 m in 2003 and 0.7 m in 2004. In 2002 and 2004, significant fractions (between one third and one half) of level ice were found to consist of rafted ice segments. Snow depth varied significantly between years, with 2004 data showing more than half the snow cover on level ice to be at or below 0.05 m depth in late spring. Ice growth simulations and examination of ice drift and deformation history indicate that impacts of atmospheric and oceanic warming on level ice thickness in the region over the past few decades are masked to a large extent by variability in snow depth and the contribution of deformation processes. In comparison with submarine sonar ice thickness data from previous decades, a reduction in ice thickness by about 0.5 to 1 m is in part explained by the replacement of multi-year with first-year ice over the Chukchi and Beaufort shelves

Ship-borne electromagnetic induction sounding of sea ice thickness in the Arctic during summer 2003

Measurements of ice thickness were carried out by a ship-borne electromagnetic induction instrument mounted on the R/V Xuelong during the Second Chinese National Arctic Research Expedition (CHINARE-2003) in summer 2003 in the Chukchi Sea. A 1-D multi-layer model, consisting of three layers of snow, ice and seawater, was used to calculate the total thickness of snow and sea ice. The time series of total thickness from 24 August to 7 September 2003 indicates that deformed and second-/multi-year ice floes appear frequently in very close pack ice farther from the ice edge, while thinner ice floes less than 1 m are frequently found in open pack ice. The probability density function of total thickness shows that a major peak appears at around 1.5 m thickness in very close pack ice, presumably corresponding to second-year or deformed ice. Also shown is a peak at around 0.3 m thickness, corresponding to typical level ice in open pack ice

La “crise” de l’enseignement du français : qu’en dit la recherche ?

Contrairement aux idées reçues sur la baisse continue de niveau, le laxisme délibéré des institutions ou les carences éducatives supposées des classes populaires, les acquis des sciences humaines insistent au contraire sur l’importance fondamentale de l’évolution du rapport entre temps disponible et contenus de formation prescrits (au collège le volume horaire alloué au français et aux langues vivantes et anciennes passe d’environ 13 heures dans la première moitié du vingtième siècle à 7h50 en 1989). Ces acquis permettent aussi de montrer que l’école reste un espace de compétition entre familles, voire « classes sociales », où les inégalités sociales se déplacent et se renouvèlent. Si aucune réponse simple ne peut être apportée à ces questions, il apparait toutefois prioritaire de définir plus précisément un socle de compétences communes et de donner à chaque élève des conditions de travail égales