SUMMARYArabidopsis seed size is regulated by the IKU pathway that includes IKU2 (a leucine-rich repeat kinase) and MINI3 (a WRKY transcription factor). We report the cloning of the IKU1 (At2g35230) gene. iku1 mutants cause reduced endosperm growth and the production of small seeds. IKU1 encodes a protein containing a VQ motif, which is a motif specific to plants. IKU1 is expressed in the early endosperm and its progenitor, the central cell. Restoration of IKU1 function in the endosperm is sufficient to rescue seed size. A genomic construct carrying mutations in the VQ motif failed to complement the iku1 mutation, suggesting an essential role for the VQ motif. IKU1 interacts with MINI3 in the yeast two-hybrid system, consistent with an IKU1 function in the IKU-MINI pathway. Our data support the proposition that endosperm development is an important determinant of seed size.
Crude extracts of 52 marine bacteria associated with sponges, which were collected from the sea near San Juan Island, Washington, USA, were screened using diatom attachment assays against Amphora sp., Nitzschia closterium, Sellaphora sp. and Stauroneis sp. to investigate their antidiatom activities. Among these samples, five expressed strong anti-adhesion effects on all four tested diatoms. There was no negative effect observed from those five active samples on the growth of Amphora sp. Those five active samples were prepared from respective isolates, which all belonged to the genus Bacillus based on 16S rRNA gene sequencing analysis. The results of present study indicate that Bacillus may play important roles for sponges' chemical defence against biofouling of diatoms and that the metabolites of Bacillus may be a potential source of natural antifouling compounds.
Dimethyl sulfide (DMS) emitted from the petrochemical industry is a typical volatile organic sulfur compound (VOSC) with poor solubility and odorous smell. A microbial fuel cell (MFC) is regarded as an appreciative method for simultaneous DMS degradation and electricity generation. In this work, for the first time, we developed an MFC system for DMS treatment. With an initial concentration of 95 mg L −1 , the DMS removal efficiency at the closed-circuit state was achieved as high as 89.5% within 40 h, which was 1.21 times higher than that at the open-circuit state. The maximum power density and current density were 0.237 mW m −2 and 2.644 mA m −2 , respectively. The dominant electrogenic bacteria in the MFC were Stenotrophomonas, Pseudomonas, and Candidatus Microthrix, and the DMS degraders included Thiobacillus, Truepera, and Candidatus Microthrix. Direct extracellular electron transfer was involved in the bioanode for DMS degradation according to the CV curves. Moreover, to overcome the toxicity of high-concentration DMS on microorganisms and enhance power generation, sodium acetate (NaAc) was added as a co-substrate, resulting in 52.5% increase in DMS degradation activity and a 16.5 times higher maximum output voltage. Overall, these findings may offer basic information for bioelectrochemical degradation of DMS and facilitate the application of MFCs in waste gas treatment.
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