Distribution of microaerophilic bacteria through the oxic-anoxic transition zone of lagoon sediments

In marine sediments, where soluble gases diffuse only very slightly, many organisms struggle for molecular oxygen. Microaerophilic bacteria, able to grow at reduced pO₂ between 0.2 and 12%, have an advantage. Distribution of aerobes, microaerophiles and anaerobes was compared with the oxygen gradient in seawater and sediment samples collected in a northern Mediterranean lagoon. In the near bottom seawater and in the 0–10 mm upperlayer of sediment, the microaerophilic counts were less than 1% of aerobe densities. In the 10–15 mm zone, these two groups were equivalent in density (1 × 10⁵ cells ml^–1). As expected, the microaerophiles took advantage of their low oxygen tension requirements in the subsurface sediments, between the well aerated zone (0–5 mm depth) and the low redox potential zone. Then, beyond a depth of 20 mm, the anaerobes prevailed in this sandy clay.     

Expression of the green fluorescent protein gene in conifer tissues

The gene coding for the green fluorescent protein (GFP) from jellyfish was introduced into conifer tissues by microprojectile bombardment and its transient expression was detected. Two versions of the GFP gene, wild-type GFP and modified GFP with a cryptic intron removed, were directly compared for their expression in black spruce pollen. While the wild-type GFP gene resulted in a low level of expression, the modified GFP gene gave a dramatic increase in amount of expression (>100 times). The expression of GFP was detected in all the tissues tested : pollen, embryonal masses, suspension culture, and somatic embryos. Also, the GFP gene was introduced and expressed in three different conifer species (black spruce, white spruce, and white pine). The successful expression of the GFP gene in various tissues and different species suggests that it will be a useful reporter/marker gene for conifers.Abbreviations GUS -glucuronidase - NOS nopaline synthase - NPTII neomycin phosphotransferase - CaMV cauliflower mosaic virus Communicated by S. Gleddie     

Recurrent fruit harvesting reduces seedling density but increases the frequency of clonal reproduction in a tropical tree

Studies on the ecological impacts of non‐timber forest products (NTFP) harvest reveal that plants are often more resilient to fruit and seed harvest than to bark and root harvest. Several studies indicate that sustainable fruit harvesting limits can be set very high (>80% fruit harvesting intensity). For species with clonal and sexual reproduction, understanding how fruit harvest affects clonal reproduction can shed light on the genetic risks and sustainability of NTFP harvest. We studied 18 populations of a gallery forest tree, Pentadesma butyracea (Clusiaceae), to test the impact of fruits harvest, climate and habitat size (gallery forest width) on the frequency of sexual or clonal recruitment in Benin, West Africa. We sampled populations in two ecological regions (Sudanian and Sudano‐Guinean) and in each region, we selected sites with low, moderate and high fruit harvesting intensities. These populations were selected in gallery forests with varying width to sample the natural variation in P. butyracea habitat size. Heavily harvested populations produced significantly less seedlings but had the highest density and proportion of clonal offspring. Our study suggests that for plant species with dual reproductive strategy (via seeds and clonal), fruit harvesting and associated disturbances that come with it can lead to an increase in the proportion of clonal offspring. This raises the issue that excessive fruit harvest by increasing the proportion of clonal offspring to the detriment of seed originated offspring may lead to a reduction in genetic diversity with consequence on harvested species capability to withstand environmental stochasticity.     

Mixed Phase Solid‐State Plastic Crystal Electrolytes Based on a Phosphonium Cation for Sodium Devices

Na batteries are seen as a feasible alternative technology to lithium ion batteries due to the greater abundance of sodium and potentially similar electrochemical behavior. In this work, mixed phase electrolyte materials based on solid‐state compositions of a tri methylisobutylphosphonium (P_111i4) bis(tri fluromethanesulphonyl)amide (NTf₂) organic ionic plastic crystal (OIPC) and high concentration of NaNTf₂ that support safe, sodium metal electrochemistry are demonstrated. A Na symmetric cell can be cycled efficiently, even in the solid state (at 50 °C and 60 °C), for a 25 mol% (P_111i4NTf₂)–75 mol% NaNTf₂ composition at 0.1 mA cm^?2 for 100 cycles. Thus, these mixed phase materials can be potentially used in Na‐based devices under moderate temperature conditions. It is also investigated that the phase behavior, conductivity, and electrochemical properties of mixtures of NaNTf₂ with this OIPC. It is observed that these mixtures have complex phase behavior. For high compositions of the Na salt, the materials are solid at room temperature and retain a soft solid consistency even at 50 °C with remarkably high conductivity, approaching that of the pure ionic liquid at 50 °C, i.e., 10^?3–10^?2 S cm^?1.