Synthesis and in vitro anti Mycobacterium tuberculosis activity of a series of phthalimide derivatives

New phthalimide derivatives were easily prepared through condensation of phthalic anhydride and selected amines with variable yields (70–90%). All compounds (3a–l) were evaluated against Mycobacterium tuberculosis H₃₇Rv using Alamar Blue susceptibility. The compounds 3c, 3i, and 3l have the minimum inhibitory concentrations (MICs) of 3.9, 7.8, and 5.0 μg/mL, respectively, and could be considered new lead compounds in the treatment of tuberculosis and multi-drug resistant tuberculosis.     

Synthesis and Stability of Chloroplast Ribosomal-RNA's

The chloroplast ribosomal-RNAs (1.1 × 10⁶ and 0.56 × 10⁶ mol wt) are synthesized in the normal ratio of 2:1. The non-ribosomal distribution observed after extraction and fractionation results from the lability of the 1.1 × 10⁶ component, and a correction for this breakdown can be applied in certain cases. Newly synthesized 1.1 × 10⁶ RNA is more stable than the older accumulated 1.1 × 10⁶ RNA. Accumulation of the chloroplast RNA during growth of radish cotyledons occurs at a later time than the accumulation of cytoplasmic RNA, and its turnover is much less than that of the cytoplasmic ribosomal-RNA.     

Variation in satellite DNA from some higher plants

Pure satellite DNAs were prepared as minor components after centrifugation to equilibrium on CsCl gradients. A single satellite DNA band was isolated from flax (Linum usitatissimum) DNA and two bands were resolved in cucumber (Cucumis sativus) DNA. These apparently homogeneous components of the plant genomes were further analyzed by thermal denaturation and renaturation. The flax satellite DNA appeared homogeneous on thermal denaturation but was shown to contain several components of renaturation. The two cucumber satellite DNAs were different from each other, but both showed at least two components in denaturation and renaturation analyses. Renaturation in the three satellites, particularly in flax, was inaccurate, indicating a considerable degree of sequence divergence. Although each satellite contained quite large amounts of simple repetitious sequences, a residual heterogeneous DNA fraction was always present. It is considered that this was too large a portion of the satellite DNA to be due to organelle or ribosomal DNA in cucumber. The latter possibility is precluded in flax, where the satellite is completely resolved in buoyant density from both organelle and ribosomal DNA.     

6DMAP inhibits chromatin decondensation but not sperm histone kinase in sea urchin male pronuclei

Treatment of sea urchin eggs for 10 min prior to fertilization with the kinase inhibitor 6DMAP (6-dimethylaminopurine) reversibly inhibits swelling and loss of conical morphology of the male pronucleus. Male pronuclei inhibited with 1 mM 6DMAP for 25 min undergo phosphorylation of Sp H1 and Sp H2B histones as fully as do control nuclei. Therefore, Sp histone kinase, whose target sequences resemble those of the M-phase histone kinase, is not inhibited by 6DMAP, and Sp histone phosphorylation, although it may be necessary, is not sufficient for chromatin decondensation.     

The stability, polyadenylic acid content and ribonucleoprotein form of nulcear ribonucleic acid in artichoke.

A nuclear preparation, containing 60-80% of the total tissue DNA and less than 0.5% of the total rRNA, was used to characterize the nuclear RNA species synthesized in cultured artichoke explants. The half-lives of the nuclear RNA species were estimated from first-order-decay analyses to be: hnRNA (heterogeneous nuclear RNA) containing poly(A), 38 min; hnRNA lacking poly(A), 37 min; 2.5 X 10(6)-mol. wt. precursor rRNA, 24 min; 1.4 X 10(6)-mol.wt. precursor rRNA, 58 min; 1.0 X 10(6)-mol.wt. precursor rRNA, 52 min. The shorter half-lives are probably overestimates, owing to the time required for equilibration of the nucleotide-precursor pools. The pathway of rRNA synthesis is considered in terms of these kinetic measurements. The rate of accumulation of cytoplasmic polydisperse RNA suggested that as much as 40% of the hnRNA may be transported to the cytoplasm. The 14-25% of the hnRNA that contained a poly(A) tract had an average molecular size of 0.7 X 10(6) daltons. The poly(A) segment was 40-200 nucleotides long, consisted of at least 95% AMP and accounted for 8-10% of the [32P]orthophosphate incorporated into the poly(A)-containing hnRNA. Ribonucleoprotein particles released from nuclei by sonication, lysis in EDTA or incubation in buffer were analysed by sedimentation through sucrose gradients and by isopycnic centrifugation in gradients of metrizamide and CsCl. More than 50% of the hnRNA remained bound to the chromatin after each treatment. The hnRNA was always associated with protein but the densities of isolated particles suggested that the ratio of protein to RNA was lower than that reported for mammalian cells, The particles separated from chromatin were not enriched for poly(A)-containing hnRNA.     

The complexity of satellite deoxyribonucleic acid in a higher plant.

Purified satellite DNA from melon (Cucumis melo) was shown to contain at least two components from thermal-denaturation and renaturation studies. Two components were separated after partial renaturation, a fast-renaturing fraction similar in complexity to mouse satellite DNA, and one with 6000 times greater complexity. Both components renatured very accurately, indicating a minimum of sequence divergence. Centrifugation of the purified satellite DNA in Ag+/Cs2SO4 gradients resolved two major and several minor fractions. The two major fractions were only slightly enriched for fast- or slow-renaturing sequences.     

Homogeneous Canine Chest Phantom Construction: A Tool for Image Quality Optimization

Digital radiographic imaging is increasing in veterinary practice. The use of radiation demands responsibility to maintain high image quality. Low doses are necessary because workers are requested to restrain the animal. Optimizing digital systems is necessary to avoid unnecessary exposure, causing the phenomenon known as dose creep. Homogeneous phantoms are widely used to optimize image quality and dose. We developed an automatic computational methodology to classify and quantify tissues (i.e., lung tissue, adipose tissue, muscle tissue, and bone) in canine chest computed tomography exams. The thickness of each tissue was converted to simulator materials (i.e., Lucite, aluminum, and air). Dogs were separated into groups of 20 animals each according to weight. Mean weights were 6.5 ± 2.0 kg, 15.0 ± 5.0 kg, 32.0 ± 5.5 kg, and 50.0 ± 12.0 kg, for the small, medium, large, and giant groups, respectively. The one-way analysis of variance revealed significant differences in all simulator material thicknesses (p < 0.05) quantified between groups. As a result, four phantoms were constructed for dorsoventral and lateral views. In conclusion, the present methodology allows the development of phantoms of the canine chest and possibly other body regions and/or animals. The proposed phantom is a practical tool that may be employed in future work to optimize veterinary X-ray procedures.     

In vitro assay for testing the toxicity of Bacillus thuringiensis subsp. israelensis delta endotoxin using blood agarose plates

An in vitro assay system that used erythrocytes was developed to assess the toxicity of delta endotoxin of Bacillus thuringiensis subsp. israelensis (Bti), a mosquito larvicidal agent. This endotoxin was activated at high alkaline pH without causing alkaline injury to the erythrocytes. The assay is carried out on blood agarose plates, prepared in MOPS-buffered saline (0·01 mol 1^-1), pH 7·0. The threshold dose for toxicity of Bti HD-567 was 8 ng protein and that of Bti H-14 and IPS-82 standard were 6 ng and 4 ng protein respectively. The assay is rapid, sensitive, quantitative and applicable to different Bti formulations to assess the toxicity of the products. Only the activated toxin is detected by this method and has good correlation with insect bioassay. The percentage toxicity dose of different Bti preparations agrees well with percentages of LC₅₀ values when the second instar larvae of Aedes aegypti were tested.