Nucleotide sequence of Citrus limon 26S rRNA gene and secondary structure model of its RNA

The complete nucleotide sequence of Citrus limon 26S rDNA has been determined. The sequence has been aligned with large ribosomal RNA (L-rRNA) sequences of Escherichia coli, Saccharomyces cerevisiae and Oryza sativa. Nine extensive expansion segments in dicot 26S rRNA relative to E. coli 23S rRNA have been identified and compared with analogous segments of monocot, yeast, amphibian and human L-rRNAs. A secondary structure model for lemon 26S rRNA has been derived based on the refined model of E. coli 23S rRNA. It has been compared with other eukaryotic L-rRNAs models in terms of location of functionally important regions. Origin and evolution of L-rRNA expansion segments are discussed.     

Raman spectroscopic elucidation of DNA backbone conformations for poly(dG-dT).poly(dA-dC) and poly(dA-dT).poly(dA-dT) in CsF solution

Raman spectra have been recorded for poly(dG-dT) · poly(dA-dC) and poly(dA-dT) · poly(dA-dT) in low salt and at high concentrations of CsF. Poly(dG-dT) · poly(dA-dC) shows no change in the 682-cm^?1 guanine mode, demonstrating the absence of the Z-structure at high salt. The 790-cm^?1 phosphodiester symmetric stretch, however, shifts up 5 cm^?1 in 4.3M CsF, suggesting a slight conformational change, associated with ion binding or hydration changes. Poly(dA-dT) · poly(dA-dT) shows an additional broad band at 816 cm^?1, attributed to the phosphodiester modes associated with the C3′-endo deoxyribose units in the alternating B-structure. In this case, both the 841- and the 816-cm^?1 asymmetric phosphodiester stretches, associated with the C2′- and C3′-endo units, shift down on addition of CsF in a sequential manner. Correlation of this sequence with that previously observed for the two ³¹P-nmr resonances, establishes that the phosphodiester stretching frequencies depend on the conformation of the 5′-sugar, and not on the 3′-sugar.     

A site-specific endonuclease from Pseudomonas aeruginosa

Pael, a new restriction endonuclease from Pseudomonas aeruginosa clinical strain was isolated and characterized. It recognizes and cleaves the sequence 5-GCATGC-3 generating DNA fragments with 3-tetranucleotide sticky ends. DNAs of pBR322, SV40 and bacteriophage have one, two and six Pael recognition sites, respectively.Seventytwo strains of Pseudomonas, Clostridium, Escherichia coli, Shigella, Proteus and Saccharomyces were screened for the presence of site-specific endonucleases. Here we describe the Pael restriction enzyme found in Pseudomonas aeruginosa; other data will be published elsewhere.Earlier Hinkle and Miller isolated from P. aeruginosa a PaeR7 restriction endonuclease recognizing and cleaving a sequence 5-CTCGAG-3 (1). Sequence analysis of DNAs cleaved by PaeI shows that the enzyme is the isoschizomer of SphI (2).     

Mesozooplankton of the Kosi Bay lakes,South Africa

The Kosi coastal lake system, a chain of four interconnected basins, is located in the subtropical north-eastern corner of South Africa. Little information is available on zooplankton of the system and the main aim of this study is to report on zooplankton samples collected during 2002 and 2003. The set of samples consists of seasonal, subsurface mesozooplankton samples that were collected during nighttime in each of the lakes. A well-developed salinity gradient was evident along the interconnected lakes in the subsurface water during all seasons, ranging from freshwater in the upper lake Amanzamnyama to a maximum of 22 recorded in Lake Makhawulani. The zooplankton community structures of the lakes reflected the salinity gradient of the system, with some coastal marine taxa recorded in the lakes closer to the mouth and only freshwater taxa recorded in Lake Amanzamnyama. Mesozooplankton diversity and abundance were relatively low compared to other estuarine systems along the eastern coast of South Africa. The dominant taxa were calanoid copepods Acartiella natalensis and Pseudodiaptomus stuhlmanni and the mysid Mesopodopsis africana in the lower lakes, whereas cyclopoids Mesocyclops sp. and Thermocyclops sp. dominated the freshwater lake Amanzamnyama.     

Interrogating the Dimerization Interface of the Prion Protein Via Site-Specific Mutations to p-Benzoyl-L-Phenylalanine

Transmissible spongiform encephalopathies are centered on the conformational transition of the prion protein from a mainly helical, monomeric structure to a β-sheet rich ordered aggregate. Experiments indicate that the main infectious and toxic species in this process are however shorter oligomers, formation of which from the monomers is yet enigmatic. Here, we created 25 variants of the mouse prion protein site-specifically containing one genetically-incorporated para-benzoyl-phenylalanine (pBpa), a cross-linkable non-natural amino acid, in order to interrogate the interface of a prion protein-dimer, which might lie on the pathway of oligomerization. Our results reveal that the N-terminal part of the prion protein, especially regions around position 127 and 107, is integral part of the dimer interface. These together with additional pBpa-containing variants of mPrP might also facilitate to gain more structural insights into oligomeric and fibrillar prion protein species including the pathological variants.     

Reduction of 2-methoxy-1,4-naphtoquinone by mitochondrially-localized Nqo1 yielding NAD+ supports substrate-level phosphorylation during respiratory inhibition

Provision of NAD⁺ for oxidative decarboxylation of alpha-ketoglutarate to succinyl-CoA by the ketoglutarate dehydrogenase complex (KGDHC) is critical for maintained operation of succinyl-CoA ligase yielding high-energy phosphates, a process known as mitochondrial substrate-level phosphorylation (mSLP). We have shown previously that when NADH oxidation by complex I is inhibited by rotenone or anoxia, mitochondrial diaphorases yield NAD⁺, provided that suitable quinones are present (Kiss G et al., FASEB J 2014, 28:1682). This allows for KGDHC reaction to proceed and as an extension of this, mSLP. NAD(P)H quinone oxidoreductase 1 (NQO1) is an enzyme exhibiting diaphorase activity. Here, by using Nqo1^?/? and WT littermate mice we show that in rotenone-treated, isolated liver mitochondria 2-methoxy-1,4-naphtoquinone (MNQ) is preferentially reduced by matrix Nqo1 yielding NAD⁺ to KGDHC, supporting mSLP. This process was sensitive to inhibition by specific diaphorase inhibitors. Reduction of idebenone and its analogues MRQ-20 and MRQ-56, menadione, mitoquinone and duroquinone were unaffected by genetic disruption of the Nqo1 gene. The results allow for the conclusions that i) MNQ is a Nqo1-preferred substrate, and ii) in the presence of suitable quinones, mitochondrially-localized diaphorases other than Nqo1 support NADH oxidation when complex I is inhibited. Our work confirms that complex I bypass can occur by quinones reduced by intramitochondrial diaphorases oxidizing NADH, ultimately supporting mSLP. Finally, it may help to elucidate structure-activity relationships of redox-active quinones with diaphorase enzymes.     

Correlation of iron content, spectral forms of chlorophyll and chlorophyll-proteins in iron deficient cucumber (Cucumis sativus)

Leaves and chloroplast suspensions of severely and slightly iron deficient cucumber ( Cucumis sativus L.) plants were characterized by low-temperature fluorescence emission spectroscopy and Deriphat polyacrylamide gel electrophoresis. The emission spectra of the chloroplast suspensions were resolved into Gaussian components and those changes induced by iron deficiency were related to the variations in the chlorophyll-protein pattern. The symptoms described with these methods were also correlated with the iron content of the leaves. It was concluded that the lack of physiologically active iron caused a relative decrease of photosystem I (PSI) and light harvesting complex I (LHCI), together with the long wavelength fluorescence, especially the 740 nm Gaussian component, and. to a much lesser extent, of the photosystem II (PSII) core complexes (relative increase of 685, 695 nm components). However, the relative decrease in the amount of light harvesting complex II (LHCII) was followed by a relative increase in its fluorescence band at 680 nm, showing that energy transfer from LHCII to core complex II (CCII) was partly disturbed. Thus iron deficiency affected the photosynthetic apparatus in a complex way: it decreased the synthesis of chlorophylls (Chls) and influenced the expression and assembly of Chl-binding proteins.     

Single-molecule FRET reveals the pre-initiation and initiation conformations of influenza virus promoter RNA

Influenza viruses have a segmented viral RNA (vRNA) genome, which is replicated by the viral RNA-dependent RNA polymerase (RNAP). Replication initiates on the vRNA 3′ terminus, producing a complementary RNA (cRNA) intermediate, which serves as a template for the synthesis of new vRNA. RNAP structures show the 3′ terminus of the vRNA template in a pre-initiation state, bound on the surface of the RNAP rather than in the active site; no information is available on 3′ cRNA binding. Here, we have used single-molecule Förster resonance energy transfer (smFRET) to probe the viral RNA conformations that occur during RNAP binding and initial replication. We show that even in the absence of nucleotides, the RNAP-bound 3′ termini of both vRNA and cRNA exist in two conformations, corresponding to the pre-initiation state and an initiation conformation in which the 3′ terminus of the viral RNA is in the RNAP active site. Nucleotide addition stabilises the 3′ vRNA in the active site and results in unwinding of the duplexed region of the promoter. Our data provide insights into the dynamic motions of RNA that occur during initial influenza replication and has implications for our understanding of the replication mechanisms of similar pathogenic viruses.     

Breast cancer in a patient with gynecomastia

A case of breast carcinoma in the midst of florid gynecomastia in a 20-year-old man is reported. Up to now, only two male patients under the age of 21 with breast malignancy have been described in the literature. In contrast, gynecomastia is a more common condition than generally appreciated. The association of gynecomastia, a rather common condition, and cancer of the male breast, a rather uncommon condition, is examined. Mammography is recommended as part of the workup. A new classification of gynecomastia into true, pseudo, and mixed types is suggested. Recommendations for the role of lipoplasty in the treatment of gynecomastia are made.     

Localization of substance P-like immunoreactivity in neurons and nerve terminals in the neostriatum of the rat: a correlated light and electron microscopic study

Brain Cell Biology - An antiserum, to substance P has been used to study the neostriatum of rats which has received intracerebral injections of colchicine. Both cell bodies and nerve fibres were...