Characterization of ribonucleoprotein subparticles from 50 S ribosomal subunits of Escherichia coli.

Large ribonucleoprotein subparticles were recovered upon ribonuclease digestion of the 50 S ribosomal subunits of Escherichia coli, partially deproteinized by LiCl. Both their RNA and their protein compositions were analysed. The subunits, treated with LiCl at a concentration of 5.5 m, released an homogeneous subparticle containing proteins L₃, L₄, L₁₃, L₁₇, L₂₂ and L₂₉, about 70% of the 13 S fragment of 23 S RNA and about 50% of the 18 S one. Slightly larger species of subparticles were obtained from 50 S subunits treated with LiCl at concentrations between 3 m and 5 m; they contained in addition proteins L₂₀, L₂₁ and L₂₃ or L₂, L₁₄, L₂₀, L₂₁ and L₂₃ and a few small 23 S RNA fragments. No large subparticle was recovered from the 6 m-LiCl-treated 50 S subunits which contain only proteins L₃, L₁₃ and L₁₇. These LiCl subparticles were compared with those obtained from intact, unfolded and sodium doecyl sulphatetreated 50 S subunits.These studies reveal that in the presence of 0.10 m-magnesium acetate there is a very compact area within 50 S subunits consisting of proteins L₃, L₄, L₁₃, L₁₇, L₂₂ and L₂₉ and of about 60% of 23 S RNA; this area probably has an essential structural role. The results also show that 23 S RNA has a more folded conformation when within the 50 S subunit than when isolated, this conformation being stabilized by some of the 50 S proteins, in particular proteins L₄, L₂₂, L₂₀ and L₂₁. Finally these data permit a more definite localization of the primary and/or secondary binding sites of proteins L₂, L₃, L₄, L₁₄, L₁₇, L₂₀, L₂₁ and L₂₂ on 23 S RNA.     

RNA-RNA interactions in the binding site of protein L24 on 23S ribosomal RNA of E. coli. II. Sequence analysis of the interacting fragments.

A ribonucleoprotein complex containing several RNA subfragments from the 5' part of 23S RNA was recovered after digestion of the reconstituted complex between 23S RNA and protein L24. It was suggested in the preceding paper that the RNA subfragments 4B, 10A and 9, which are widely separated in the sequence, strongly interact. These subfragments were previously partially sequenced by the classical fingerprinting methods. Their sequences have now been completed with rapid new RNA sequencing methods. We propose here a base-pairing model showing how these subfragments may interact with one another.     

The role of fish-poultry integration on fish growth performance,yields and economic benefits among smallholder farmers in sub-Saharan Africa,Tanzania

Aquaculture practices from sub-Saharan Africa are characterised by low production, owing to improper technology. Production can be increased through integrating fish farming with other existing on-farm activities, particularly livestock husbandry. We assessed the role of fish-poultry integration on all male Nile tilapia, Oreochromis niloticus growth performance, yields and economic benefits among smallholder farmers in sub-Saharan Africa, Tanzania. The study also compared phytoplankton species composition, abundance and biomass between the fish-poultry integration and non-integrated system. After 180 days of the experiment, all male O. niloticus cultured under fish-poultry integration exhibited significantly higher growth rates than those in the non-integrated system (p < 0.05). Gross fish yield (GFY), net fish yield (NFY) and net annual yields (NAY) obtained from fish-poultry integration were significantly higher than those from non-integrated system (p < 0.05). Partial enterprise budget analysis revealed that fish-poultry integration was more profitable than the non-integrated system. Moreover, fish-poultry integrated system produced significantly higher phytoplankton abundance and biomass than those from the non-integrated system. Results demonstrate that rural smallholder farmers can achieve higher growth rate, farm net yields and income by integrating all male O. niloticus with other on-farm activities than practising a stand-alone fish culture system.     

On the isolation of TI-plasmid from Agrobacterium tumefaciens.

An efficient lysis method for Agrobacterium cells was developed, which allows a reproducible isolation of the tumor inducing (TI)-plasmid. The lysis method is based on the sensitivity of this bacterium to incubation with lysozyme, n-dodecylamine,EDTA, followed by Sarkosyl, after growth in the presence of carbenicillin. We also present a procedure for the isolation of the TI-plasmid on a large scale, that might be used for the mass isolation of other large plasmids which like the TI-plasmid, can not be cleared with earlier described procedures. The purity of the plasmid preparations was determined with DNA renaturation kinetics, which method has the advantage that the plasmid need not to be in the supercoiled or open circular form.     

Leukemic histiocytic sarcoma in a captive common squirrel monkey (Saimiri sciureus) with Saimiriine Gammaherpesvirus 2 (Rhadinovirus), Saimiri sciureus lymphocryptovirus 2 (Lymphocryptovirus) and Squirrel monkey retrovirus (β-Retrovirus) coinfection

Hematopoietic neoplasia other than lymphoma and leukemia is uncommon among non-human primates. Herein, we provide the first evidence of occurrence of leukemic histiocytic sarcoma in a captive common squirrel monkey with Saimiriine Gammaherpesvirus 2 (Rhadinovirus), Saimiri sciureus lymphocryptovirus 2 (Lymphocryptovirus), and Squirrel monkey retrovirus (β-Retrovirus) coinfection.     

SECIS-binding protein 2, a key player in selenoprotein synthesis,is an intrinsically disordered protein

Selenocysteine (Sec) is co-translationally incorporated into selenoproteins at a reprogrammed UGA codon. In mammals, this requires a dedicated machinery comprising a stem-loop structure in the 3′ UTR RNA (the SECIS element) and the specific SECIS Binding Protein 2. In this report, disorder-prediction methods and several biophysical techniques showed that ca. 70% of the SBP2 sequence is disordered, whereas the RNA binding domain appears to be folded and functional. These results are consistent with a recent report on the role of the Hsp90 chaperone for the folding of SBP2 and other functionally unrelated proteins bearing an RNA binding domain homologous to SBP2.     

Cloning,Overexpression, Purification,and Characterization of the Maleylacetate Reductase from <Emphasis Type="Italic">Sphingobium chlorophenolicum</Emphasis> Strain ATCC 53874

The final enzyme in the pentachlorophenol (PCP) biodegradation pathway in Sphingobium chlorophenolicum is maleylacetate reductase (PcpE), which catalyzes the reductive dehalogenation of 2-chloromaleylacetate to maleylacetate and the subsequent reduction of malyelacetate to 3-oxoadipate. In this study, the pcpE gene was cloned from S. chlorophenolicum strain ATCC 53874 and overexpressed in Escherichia coli BL21-AI cells. The recombinant PcpE, purified to higher than 95% purity using affinity chromatography, exhibited optimal activity at pH 7.0. The kinetic parameters k _cat and K _m were 1.2 ± 0.3 s⁻¹ and 0.09 ± 0.04 mM, respectively, against maleylacetate under the optimal pH. In addition, the purified PcpE was able to restore PCP-degrading capability to S. chlorophenolicum strain ATCC 39723, implicating that there was no functional PcpE in the ATCC 39723 strain.