Epigenetic dynamics of imprinted X inactivation during early mouse development

The initiation of X-chromosome inactivation is thought to be tightly correlated with early differentiation events during mouse development. Here, we show that although initially active, the paternal X chromosome undergoes imprinted inactivation from the cleavage stages, well before cellular differentiation. A reversal of the inactive state, with a loss of epigenetic marks such as histone modifications and polycomb proteins, subsequently occurs in cells of the inner cell mass (ICM), which give rise to the embryo-proper in which random X inactivation is known to occur. This reveals the remarkable plasticity of the X-inactivation process during preimplantation development and underlines the importance of the ICM in global reprogramming of epigenetic marks in the early embryo.     

Field experiments with transformed plants reveal the sense of floral scents

Plants use many means to attract pollinators, including visual cues and odor. We investigated how nonpigment floral chemistry influences nectar removal, floral visitation, florivory, rates of outcrossing, and fitness through both male and female functions. We blocked expression of biosynthetic genes of the dominant floral attractant [benzyl acetone (Nachal1)] and nectar repellent [nicotine (Napmt1/2)] in all combinations in the native tobacco Nicotiana attenuata and measured their effects on plants in their native habitat. Both repellent and attractant were required to maximize capsule production and seed siring in emasculated flowers and flower visitation by native pollinators, whereas nicotine reduced florivory and nectar robbing.     

利用农杆菌介导法转移tfdA基因获得可遗传的抗2，4-D棉株

 本试验用农杆菌（Agrobacterium tumefaciens）菌株AGLI17-2与陆地棉（Gossypium hirsutum）栽培种晋棉7号等的下胚轴切段共培养，将2，4-D单氧化酶（tfdA）基因导入棉花愈伤组织细胞，经体细胞胚胎发生途径形成转化再生棉株。经GUS、NPTⅡ检测和DNA分子杂交（Southern Blot）证实：tfdA基因已导入转化棉株，子代2，4-D药效试验表明抗药性良好，已获得可遗传的抗2，4-D棉株。     

Protein synthesis: its control in erythropoiesis

Erythropoiesis in the fetal mouse provides a model to study several important aspects of the regulation of cell differentiation and differentiated protein synthesis. Changes in the patterns of hemoglobins formed during fetal and postfetal development are shown to be associated with the substitution of the liver erythroid cell line. In the course of differentiation of yolk sac erythroid cells there are at least two classes of proteins distinguishable with respect to dependence on continued RNA formatoin. The bulk of nuclear proteins, "nondifferentiated" proteins, appear to be dependent on relatively short-lived messenger RNA while synthesis of differentiated proteins, the hemoglobins, proceeds on relatively stable molecules of messenger RNA. Hemoglobin formation occurs in those cells which are actively synthesizing DNA and dividing. On the average, two to three cell divisions may occur after the formation and stabilization of the messenger RNA for globin. Yolk sac erythropoiesis, at least from day 10 of gestation, is unresponsive to erythropoietin. By comparison, in fetal liver erythropoiesis, the hormone, erythropoietin, acts selectively on the most immature erythroid cell precursor to induce differentiation, cell replication, and hemoglobin formation. The erythropoietin responsive cell in the liver is apparently differentiated from the progenitor, pluripotential stem cell and committed to erythroblast formation and hemoglobin synthesis on exposure to the hormone. The initial effects of erythropoietin on macromolecular synthesis are to stimulate RNA synthesis, which temporally is followed by cell replication and the increase in hemoglobin formation. During liver erythropoiesis, there appears to be a transition from hemoglobin synthesis dependent on RNA formation to hemoglobin synthesis directed by relatively stable messenger RNA.     

Root diseases, weeds, and nematodes with poultry litter and conservation tillage in a sweet corn–snap bean double crop

The effect of continuous applications of poultry litter on root diseases, nematodes, and weeds with different tillage practices in vegetable production in Georgia was investigated. Litter treatments (noncomposted and composted broiler or breeder litter) applied 3–5 weeks before planting were compared with no litter. In sweet corn and snap bean there were differences among years, and tillage and litter treatments had a variable effect on yield, post-emergence damping-off and plant stand. Crown and brace root rot in corn induced by Rhizoctonia solani AG 2-2 increased after 3 years conservation tillage, but there were no differences among litter treatments. Population densities of R. solani AG-4 were increased by conservation tillage before planting snap bean the first year but not in later years, while litter treatments had no effect. After 3 years, populations of Pythium spp., Fusarium solani, and Fusarium spp. did not differ among treatments, but noncomposted broiler litter increased populations of saprophytic fungi in soil compared with no litter. Population densities of stylet-bearing nematodes were low and usually not different among treatments. After 3 years of sweet corn populations of Meloidogyne incognita increased with conventional tillage compared with conservation tillage, populations of Paratrichodorus christiei were reduced by litter treatments and populations of Helicotylenchus dihystera were reduced by noncomposted broiler litter compared with no litter. Weed infestation increased in both tillage systems with time, but in snap bean there was a greater infestation in conservation tillage than in conventional tillage. Litter treatments had little effect on weed infestation.     

Assessing the benefits of the marine protected area of Punta Coles,southern Peru (south-east Pacific) on productivity of conspicuous benthic species using pre-image population analysis

1. The coastal marine protected ecosystem at Punta Coles (as a part of the Reserva Nacional de Islas, Islotes y Puntas Guaneras) is located in a highly exploited area in southern Peru and contains several commercial, bioengineering and other benthic species.
2. Pre-image population analysis was used to estimate the transient values of intrinsic growth rate (r) based on biomass and density time series as a proxy of productivity to assess the effectiveness of protection.
3. The outcomes obtained showed that the gastropods Concholepas concholepas, Fissurella latimartiginata and the tunicate Purya chilensis showed a reduction of productivity during recent years, whilst the sea urchin Loxechinus albus, the barnacle Balanus laevis and the bivalve Semimytilus algosus showed an opposite pattern. Several species exhibited a chaotic dynamic, coinciding with the highest productivity values. In 2016 and 2017, several species exhibited a reduction of their abundance which could be delayed responses explained by changes in oceanographic conditions (reduction of coastal upwelling), La Niña event and illegal harvest.
4. The above notwithstanding, the results suggest that effective protection of benthic species in the protected ecosystem of Punta Coles have been partially accomplished. Therefore, this work could be considered a baseline study, permitting the subsequent monitoring of productivity of the main species inhabiting the coastal area of Punta Coles.
5. Pre-image population analysis could be used as a complimentary analytical tool since it enables the evaluation of transient population parameters (e.g. productivity) thus aiding population management, conservation and monitoring decisions.