Hydrocarbon-degrading bacteria and the bacterial community response in gulf of Mexico beach sands impacted by the deepwater horizon oil spill

A significant portion of oil from the recent Deepwater Horizon (DH) oil spill in the Gulf of Mexico was transported to the shoreline, where it may have severe ecological and economic consequences. The objectives of this study were (i) to identify and characterize predominant oil-degrading taxa that may be used as model hydrocarbon degraders or as microbial indicators of contamination and (ii) to characterize the in situ response of indigenous bacterial communities to oil contamination in beach ecosystems. This study was conducted at municipal Pensacola Beach, FL, where chemical analysis revealed weathered oil petroleum hydrocarbon (C₈ to C₄₀) concentrations ranging from 3.1 to 4,500 mg kg⁻¹ in beach sands. A total of 24 bacterial strains from 14 genera were isolated from oiled beach sands and confirmed as oil-degrading microorganisms. Isolated bacterial strains were primarily Gammaproteobacteria, including representatives of genera with known oil degraders (Alcanivorax, Marinobacter, Pseudomonas, and Acinetobacter). Sequence libraries generated from oiled sands revealed phylotypes that showed high sequence identity (up to 99%) to rRNA gene sequences from the oil-degrading bacterial isolates. The abundance of bacterial SSU rRNA gene sequences was ∼10-fold higher in oiled (0.44 × 10⁷ to 10.2 × 10⁷ copies g⁻¹) versus clean (0.024 × 10⁷ to 1.4 × 10⁷ copies g⁻¹) sand. Community analysis revealed a distinct response to oil contamination, and SSU rRNA gene abundance derived from the genus Alcanivorax showed the largest increase in relative abundance in contaminated samples. We conclude that oil contamination from the DH spill had a profound impact on the abundance and community composition of indigenous bacteria in Gulf beach sands, and our evidence points to members of the Gammaproteobacteria (Alcanivorax, Marinobacter) and Alphaproteobacteria (Rhodobacteraceae) as key players in oil degradation there.     

CRISPR/Cas9: a promising way to exploit genetic variation in plants

Creation of variation in existing gene pool of crop plants is the foremost requirement in crop improvement programmes. Genome editing is a tool to produce knock out of target genes either by introduction of insertion or by deletion that disrupts the function of a specific gene. The CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9) system is the most recent addition to the toolbox of sequence-specific nucleases that includes ZFNs and TALENs. The CRISPR/Cas9 system allows targeted cleavage of genomic DNA guided by a small noncoding RNA, resulting in gene modifications by both non-homologous end joining and homology-directed repair mechanisms. Here, we present an overview of mechanisms of CRISPR, its potential roles in creating variation in germplasm and applications of this novel interference pathway in crop improvement. The availability of the CRISPR/Cas9 system holds promise in facilitating both forward and reverse genetics and will enhance research in crops that lack genetic resources.     

A degron-based strategy reveals new insights into Aurora B function in C. elegans

The widely conserved kinase Aurora B regulates important events during cell division. Surprisingly, recent work has uncovered a few functions of Aurora-family kinases that do not require kinase activity. Thus, understanding this important class of cell cycle regulators will require strategies to distinguish kinase-dependent from independent functions. Here, we address this need in C. elegans by combining germline-specific, auxin-induced Aurora B (AIR-2) degradation with the transgenic expression of kinase-inactive AIR-2. Through this approach, we find that kinase activity is essential for AIR-2’s major meiotic functions and also for mitotic chromosome segregation. Moreover, our analysis revealed insight into the assembly of the ring complex (RC), a structure that is essential for chromosome congression in C. elegans oocytes. AIR-2 localizes to chromosomes and recruits other components to form the RC. However, we found that while kinase-dead AIR-2 could load onto chromosomes, other components were not recruited. This failure in RC assembly appeared to be due to a loss of RC SUMOylation, suggesting that there is crosstalk between SUMOylation and phosphorylation in building the RC and implicating AIR-2 in regulating the SUMO pathway in oocytes. Similar conditional depletion approaches may reveal new insights into other cell cycle regulators.     

Studies on reaction of glutathionylcobalamin with hypochlorite. Evidence of protective action of glutathionyl-ligand against corrin modification by hypochlorite

Glutathionylcobalamin (GSCbl), a tight complex of glutathione (GSH) with cobalamin(III), is readily oxidized to aquacobalamin by hypochlorite. Corrin macrocycle remains unmodified in the presence of threefold excess of hypochlorite, whereas aqua- and cyanocobalamins are partially transformed to chlorinated species under the same conditions. The suggested mechanism of reaction between GSCbl and hypochlorite involves subsequent oxidation of thiol and amino groups and dissociation of oxidized glutathione from Co(III)-ion.     

Revision of the Lispe longicollis-group (Diptera,?Muscidae)

The Lispe longicollis species-group is revised. Lispe ethiopica sp. n. is described. The following 3 new synonyms are established: Lispe assimilis Wiedemann, 1824 (syn: cyrtoneurina Stein, 1900 and modesta Stein, 1913); Lispe manicata Wiedemann, 1830 (syn: forficata Kurahashi & Shinonaga, 2009). Female of Lispe microptera Seguy, 1937 is described for the first time. Identification key for known Eurasian and African species is given.